79 results on '"Siwon Kim"'
Search Results
2. Deep learning-assisted active noise control in a time-varying environment
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Seonghun Im, Siwon Kim, Sunghwa Woo, Inman Jang, Taewoo Han, Uiwon Hwang, Won-Suk Ohm, and Myunghan Lee
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Mechanics of Materials ,Mechanical Engineering - Published
- 2023
3. Electrode-level strategies enabling kinetics-controlled metallic Li confinement by the heterogeneity of interfacial activity and porosity
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Hong Rim Shin, Siwon Kim, Junho Park, Jung Ho Kim, Min-Sik Park, and Jong-Won Lee
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Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,General Materials Science - Published
- 2023
4. 'La fantaisie dans la poésie de Jules Supervielle - Gravitations et le refuge irréel'
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Siwon Kim
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General Medicine - Published
- 2022
5. Imbalanced Data Classification via Cooperative Interaction Between Classifier and Generator
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Dahuin Jung, Hyun-Soo Choi, Siwon Kim, and Sungroh Yoon
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Structure (mathematical logic) ,Generator (computer programming) ,Computer Networks and Communications ,Computer science ,business.industry ,Machine learning ,computer.software_genre ,Regularization (mathematics) ,Imbalanced data ,Computer Science Applications ,ComputingMethodologies_PATTERNRECOGNITION ,Artificial Intelligence ,Decision boundary ,Artificial intelligence ,Cooperative interaction ,business ,computer ,Classifier (UML) ,Software - Abstract
Learning classifiers with imbalanced data can be strongly biased toward the majority class. To address this issue, several methods have been proposed using generative adversarial networks (GANs). Existing GAN-based methods, however, do not effectively utilize the relationship between a classifier and a generator. This article proposes a novel three-player structure consisting of a discriminator, a generator, and a classifier, along with decision boundary regularization. Our method is distinctive in which the generator is trained in cooperation with the classifier to provide minority samples that gradually expand the minority decision region, improving performance for imbalanced data classification. The proposed method outperforms the existing methods on real data sets as well as synthetic imbalanced data sets.
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- 2022
6. A Study on the Bias and Regulation of AI Algorithm
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Seunghyun Kim, Siwon Kim, and Jungmihn J. Ahn
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General Medicine - Published
- 2022
7. Flattening of Lithium Plating in Carbonate Electrolytes Enabled by All‐In‐One Separator
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Yong Min Kim, Hyun‐seung Kim, Bo Keun Park, Jin Hyeok Yang, Han Jun Leem, Jisang Yu, Siwon Kim, So Yeun Kim, Jong‐Won Lee, Min‐Sik Park, and Ki Jae Kim
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Biomaterials ,General Materials Science ,General Chemistry ,Biotechnology - Published
- 2023
8. Les traces du Parnasse et la beauté plastique dans les ‘vers anciens’ de Paul Valéry
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Siwon KIM
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys - Published
- 2022
9. Le récit de héros féminin et la rhétorique du mélodrame dans Sémiramis de Paul Valéry
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Siwon KIM
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys - Published
- 2021
10. Optimization and Evaluation of Novel Antifungal Agents for the Treatment of Fungal Infection
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Ye Rim Lee, Kyung-Tae Lee, Dong-Gi Lee, Hyeon Jeong Kim, Eunji Cheong, Jong Hyun Park, Hyeon Ji Kim, Seul Ki Yeon, Yong Sun Bahn, Myung Ha Lee, Jiwon Choi, Da-Hee Kim, Siwon Kim, Kyung Jin Seo, Bo Ko Jang, Sun Jun Park, Jong-Seung Lee, and Ki Duk Park
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Male ,Antifungal ,Antifungal Agents ,Nail Infection ,medicine.drug_class ,Antifungal drugs ,Drug Evaluation, Preclinical ,Microbial Sensitivity Tests ,Microbiology ,Rats, Sprague-Dawley ,Mice ,Cell Wall ,Drug Discovery ,medicine ,Animals ,Humans ,Chemistry ,Fungi ,Drug Synergism ,Fungicide ,Mycoses ,Cell wall integrity ,Minimum Inhibitory Concentration Test ,Molecular Medicine ,Female ,Ex vivo - Abstract
Due to the increased morbidity and mortality by fungal infections and the emergence of severe antifungal resistance, there is an urgent need for new antifungal agents. Here, we screened for antifungal activity in our in-house library through the minimum inhibitory concentration test and derived two hit compounds with moderate antifungal activities. The hit compounds' antifungal activities and drug-like properties were optimized by substituting various aryl ring, alkyl chain, and methyl groups. Among the optimized compounds, 22h was the most promising candidate with good drug-like properties and exhibited potent fast-acting fungicidal antifungal effects against various fungal pathogens and synergistic antifungal activities with some known antifungal drugs. Additionally, 22h was further confirmed to disturb fungal cell wall integrity by activating multiple cell wall integrity pathways. Furthermore, 22h exerted significant antifungal efficacy in both the subcutaneous infection mouse model and ex vivo human nail infection model.
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- 2021
11. Deciphering the critical degradation factors of solid composite electrodes with halide electrolytes: Interfacial reaction versus ionic transport
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Jonghyeok Yun, Hong Rim Shin, Trung Dinh Hoang, Siwon Kim, Jae Hyuk Choi, Beomsu Kim, Hyuck Jung, Janghyuk Moon, and Jong-Won Lee
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Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,General Materials Science - Published
- 2023
12. KDS2010, a Newly Developed Reversible MAO-B Inhibitor, as an Effective Therapeutic Candidate for Parkinson’s Disease
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Hyowon Lee, C. Justin Lee, Siwon Kim, Sang-Wook Kim, Sang Ryong Jeon, Soo Jin Oh, Min-Ho Nam, Jun Young Heo, Jiwon Choi, Sun Jun Park, Hyung Ho Yoon, Hyo Jung Song, Jong Hyun Park, Ki Duk Park, Heeyoung An, Bo Ko Jang, Doo-Wan Cho, Su-Cheol Han, Young-Su Yang, and Hyeon Jeong Kim
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Male ,Monoamine Oxidase Inhibitors ,Parkinson's disease ,α-Aminoamide derivative ,Monoamine oxidase ,Nigrostriatal pathway ,Pharmacology ,Neuroprotection ,Mice ,chemistry.chemical_compound ,Drug Development ,Parkinsonian Disorders ,medicine ,Animals ,Pharmacology (medical) ,MAO-B inhibitor ,Monoamine Oxidase ,Reactive glia ,Dose-Response Relationship, Drug ,business.industry ,MPTP ,Parkinsonism ,medicine.disease ,Rats ,Macaca fascicularis ,Treatment Outcome ,medicine.anatomical_structure ,chemistry ,Toxicity ,Parkinson’s disease ,Original Article ,Female ,Neurology (clinical) ,Monoamine oxidase B ,business - Abstract
Monoamine oxidase-B (MAO-B) is a well-established therapeutic target for Parkinson’s disease (PD); however, previous clinical studies on currently available irreversible MAO-B inhibitors have yielded disappointing neuroprotective effects. Here, we tested the therapeutic potential of KDS2010, a recently synthesized potent, selective, and reversible MAO-B inhibitor in multiple animal models of PD. We designed and synthesized a series of α-aminoamide derivatives and found that derivative KDS2010 exhibited the highest potency, specificity, reversibility, and bioavailability (> 100%). In addition, KDS2010 demonstrated significant neuroprotective and anti-neuroinflammatory efficacy against nigrostriatal pathway destruction in the mouse MPTP model of parkinsonism. Treatment with KDS2010 also alleviated parkinsonian motor dysfunction in 6-hydroxydopamine-induced and A53T mutant α-synuclein overexpression rat models of PD. Moreover, KDS2010 showed virtually no toxicity or side effects in non-human primates. KDS2010 could be a next-generation therapeutic candidate for PD. Supplementary Information The online version contains supplementary material available at 10.1007/s13311-021-01097-4.
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- 2021
13. 'L'imaginaire ?cologique dans la po?sie de Jules Supervielle: le monde avec ‘les amis inconnus’'
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Siwon Kim
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys - Published
- 2021
14. Pre-Training of Deep Bidirectional Protein Sequence Representations With Structural Information
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Seonwoo Min, Seunghyun Park, Sungroh Yoon, Byunghan Lee, Siwon Kim, and Hyun-Soo Choi
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semi-supervised learning ,FOS: Computer and information sciences ,Scheme (programming language) ,Computer Science - Machine Learning ,General Computer Science ,Machine Learning (stat.ML) ,Machine learning ,computer.software_genre ,behavioral disciplines and activities ,Machine Learning (cs.LG) ,Bridging (programming) ,representation learning ,Statistics - Machine Learning ,Quantitative Biology - Genomics ,General Materials Science ,protein structure ,computer.programming_language ,Genomics (q-bio.GN) ,Sequence ,Interpretation (logic) ,business.industry ,General Engineering ,Biomolecules (q-bio.BM) ,TK1-9971 ,Task (computing) ,ComputingMethodologies_PATTERNRECOGNITION ,Recurrent neural network ,Quantitative Biology - Biomolecules ,FOS: Biological sciences ,Task analysis ,Electrical engineering. Electronics. Nuclear engineering ,Language model ,Artificial intelligence ,business ,Protein sequence ,computer ,psychological phenomena and processes - Abstract
Bridging the exponentially growing gap between the numbers of unlabeled and labeled protein sequences, several studies adopted semi-supervised learning for protein sequence modeling. In these studies, models were pre-trained with a substantial amount of unlabeled data, and the representations were transferred to various downstream tasks. Most pre-training methods solely rely on language modeling and often exhibit limited performance. In this paper, we introduce a novel pre-training scheme called PLUS, which stands for Protein sequence representations Learned Using Structural information. PLUS consists of masked language modeling and a complementary protein-specific pre-training task, namely same-family prediction. PLUS can be used to pre-train various model architectures. In this work, we use PLUS to pre-train a bidirectional recurrent neural network and refer to the resulting model as PLUS-RNN. Our experiment results demonstrate that PLUS-RNN outperforms other models of similar size solely pre-trained with the language modeling in six out of seven widely used protein biology tasks. Furthermore, we present the results from our qualitative interpretation analyses to illustrate the strengths of PLUS-RNN. PLUS provides a novel way to exploit evolutionary relationships among unlabeled proteins and is broadly applicable across a variety of protein biology tasks. We expect that the gap between the numbers of unlabeled and labeled proteins will continue to grow exponentially, and the proposed pre-training method will play a larger role., Comment: Published in IEEE Access 2021 (https://ieeexplore.ieee.org/document/9529198)
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- 2021
15. Le paysage de naissance au monde dans La Jeune Parque
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Siwon Kim
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys - Published
- 2020
16. Synthesis and Evaluation of Serinolamide Derivatives as Sphingosine-1-Phosphate-1 (S1P
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Sun Jun, Park, Jushin, Kim, Jaehwan, Kim, Yoowon, Kim, Elijah Hwejin, Lee, Hyeon Jeong, Kim, Siwon, Kim, Byungeun, Kim, Rium, Kim, Ji Won, Choi, Jong-Hyun, Park, and Ki Duk, Park
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Receptors, Lysosphingolipid ,Fingolimod Hydrochloride ,Sphingosine ,Lymphocytes ,Lysophospholipids - Abstract
Sphingosine-1-phosphate-1 (S1P
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- 2022
17. Counting DNA molecules on a microchannel surface for quantitative analysis
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Taesoo Kim, Siwon Kim, Chanyoung Noh, Hyeseung Hwang, Jieun Shin, Nabin Won, Seonghyun Lee, Dogeun Kim, Yoonha Jang, Su-Jin Hong, Jungyul Park, Sung Jae Kim, Seongsoo Jang, Kwang-Il Lim, and Kyubong Jo
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Microscopy, Fluorescence ,Escherichia coli ,DNA ,Microfluidic Analytical Techniques ,Analytical Chemistry ,Plasmids - Abstract
Microscopic visualization of DNA molecules is a simple, intuitive, and powerful method. Nonetheless, DNA-molecule quantification methods that employ microscopic visualization have not been reported so far. In this study, a new quantitative approach is presented that enables the counting of individual DNA molecules that have been rendered visible by fluorescence microscopy. Toward this, a microfluidic device was employed that directed DNA molecules into microchannels and deposited the molecules onto a positively charged surface. This microfluidic device had a vertically tapered channel inlet structure that prevented the accumulation of excess DNA molecules in the channel inlet while creating a tapering flow, thereby ensuring the even distribution of the DNA molecules in the microchannels. The channel heights and the density of positive charges on the surface were optimized for analysis. The linearity of this method with respect to the determination of the concentration of DNA in solutions was subsequently determined. The limit of detection was 0.48 fg/μL, which corresponds to 64 molecules of 7.25 kbp DNA in 1 μL of sample. This quantitative approach was finally used to count two types of plasmids co-transformed in an E. coli cell; a measurement that is typically considered challenging with gel electrophoresis.
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- 2022
18. Proposal of home multimedia device reflecting the behavior of video content consumption Trend for binge-watchers of Generation Z
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Siwon Kim and Chung Jae Hee
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Consumption (economics) ,Multimedia device ,Multimedia ,Computer science ,Content (measure theory) ,General Medicine ,computer.software_genre ,Media content ,computer - Published
- 2020
19. Discovery of Novel Sphingosine-1-Phosphate-1 Receptor Agonists for the Treatment of Multiple Sclerosis
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Sun Jun Park, Seul Ki Yeon, Yoowon Kim, Hyeon Jeong Kim, Siwon Kim, Jushin Kim, Ji Won Choi, Byungeun Kim, Elijah Hwejin Lee, Rium Kim, Seon Hee Seo, Jaeick Lee, Jun Woo Kim, Ha-Yeon Lee, Hayoung Hwang, Yong-Sun Bahn, Eunji Cheong, Jong-Hyun Park, and Ki Duk Park
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Male ,Encephalomyelitis, Autoimmune, Experimental ,Multiple Sclerosis ,Isoxazoles ,Triazoles ,Rats ,Mice ,Structure-Activity Relationship ,Dogs ,Heart Rate ,Drug Design ,Drug Discovery ,Molecular Medicine ,Animals ,Humans ,Lymphocyte Count ,Lymphocytes ,Sphingosine-1-Phosphate Receptors ,beta-Arrestins - Abstract
The sphingosine-1-phosphate-1 (S1P
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- 2022
20. Counting DNA Molecules on a Microchannel Surface for Quantitative Analysis
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Taesoo Kim, Siwon Kim, Chanyoung Noh, Hyeseung Hwang, Jieun Shin, Nabin Won, Dogeun Kim, Yoonha Jang, Su-Jin Hong, Jungyul Park, Sung Jae Kim, Kwang-Il Lim, Seongsoo Jang, and Kyubong Jo
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History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
21. Grounding Visual Representations with Texts for Domain Generalization
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Seonwoo Min, Nokyung Park, Siwon Kim, Seunghyun Park, and Jinkyu Kim
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- 2022
22. Rational Design of 3-Dimensional Carbon Architectures with Controlled Interfacial Activity for Reversible Li Metal Storage
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Hong Rim Shin, Siwon Kim, and Jong-Won Lee
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Three-dimensional (3D) host architectures for Li metal storage have emerged as promising strategies for resolving the critical issues of Li metal anodes: severe volume changes and dendritic growth of Li during charge–discharge processes. However, the ionic resistance of electrolyte-filled pores causes the preferential deposition of Li on top of the 3D architecture (i.e., top plating), resulting in early cell failure. To realize Li metal anodes with high capacity and cyclability, herein, we report 3D-architectured electrodes with controlled interfacial activity based on metal–organic framework (MOF)-derived carbon hosts. Electrochemical simulations of Li plating processes in the 3D-architectured electrode suggest that the top plating can be effectively suppressed by increasing the interfacial activity across the thickness toward bottom of the electrode. MOF nanoparticles are pyrolyzed to form highly porous carbon hosts, and then, atomic Ag clusters are incorporated into the host by a galvanic displacement reaction to enhance the interfacial activity. A bi-layered carbon electrode with controlled interfacial activity is fabricated via sequential electrophoretic deposition of the host materials: i.e., as-pyrolyzed carbon on top and Ag-incorporated carbon on bottom. In comparison with the conventional electrode with uniform interfacial activity, the bi-layered electrode exhibits reduced overpotentials for Li plating and enhanced cyclability during galvanostatic Li plating–stripping. The combined computational and experimental studies further demonstrate that the bottom layer with atomic Ag clusters acts as a preferential site for Li nucleation even in the presence of kinetic limitations of ionic transport. As a result, Li deposits are confined in the bi-layered carbon electrode, thereby enhancing the reversibility of Li metal storage. This work provides an effective strategy to develop long-cycling, high-capacity Li metal anodes by controlling the interfacial activity of 3D carbon architectures.
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- 2022
23. Interfacial and Charge-Transport Impedances of NCM Composite Cathodes with Halide Solid Electrolytes for All-Solid-State Batteries
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Jonghyeok Yun, Hyohyun Cha, Siwon Kim, Beomsu Kim, and Jong-Won Lee
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All-solid-state batteries (ASSBs) offer a fundamental solution to mitigate the safety and reliability issues of conventional lithium-ion batteries utilizing flammable liquid electrolytes. However, interfacial resistances between the cathode materials and solid electrolytes, which originate from poor solid-solid contacts and detrimental interfacial reactions, limit the electrochemical performances of ASSBs. Recently, various approaches have been developed to realize high-capacity composite cathodes with improved cycling stability. For example, single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) has been reported to mitigate the capacity fading resulting from cracking of commonly adopted multi-crystal NCM811. Also, halide-type solid electrolytes are reported to exhibit high Li-ion conductivity and electrochemical stability with NCM. In this work, we systematically study the interfacial and charge-transport impedances of NCM composite cathodes with halide solid electrolytes. The composite cathodes comprising single- or multi-crystal NCM811 and Li6PS5Cl or Li3InCl6 (and conductive agents) are fabricated to characterize their electrochemical impedance behaviors. In particular, we analyze the evolution of the interfacial and charge-transport impedances during charge–discharge cycling based on a multi-rail transmission line model combined with interfacial reactions. In addition, we investigate the chemical, electrochemical, and mechanical degradations of composite cathodes using various analytical tools to elucidate performance-determining factors of ASSBs.
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- 2022
24. Éléments d'écologie dans la poésie de Saint-John Perse
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Siwon Kim
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- 2019
25. Saint-John Perse et le retour de Robinson Crusoé : l’effondrement du mythe ou un nouveau mythe
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Siwon Kim
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Mechanics of Materials ,Mechanical Engineering ,Metals and Alloys - Published
- 2019
26. Pediatric Sleep Stage Classification Using Multi-Domain Hybrid Neural Networks
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Yoon Gi Chung, Hunmin Kim, Siwon Kim, Sungroh Yoon, Ki Joong Kim, Hee Hwang, Sun Ah Choi, Hyun-Soo Choi, and Yonghoon Jeon
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General Computer Science ,Computer science ,Feature extraction ,convolutional neural network ,02 engineering and technology ,Sleep staging ,Electroencephalography ,Convolutional neural network ,pediatric electroencephalography ,Hybrid neural network ,03 medical and health sciences ,0302 clinical medicine ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,General Materials Science ,Artificial neural network ,medicine.diagnostic_test ,business.industry ,instantaneous frequency features ,Deep learning ,General Engineering ,deep learning ,020207 software engineering ,Pattern recognition ,Automatic sleep staging ,Frequency domain ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,Artificial intelligence ,long short-term memory ,F1 score ,business ,lcsh:TK1-9971 ,030217 neurology & neurosurgery - Abstract
Sleep staging is an important part of clinical neurology. However, it is still performed manually by technical experts and is labor-intensive and time-consuming. To overcome these obstacles in the manual sleep staging process, a large number of machine learning-based classifiers with hand-engineered features have been proposed. Additionally, combinations of a deep neural network (DNN) have been recently highlighted as the state-of-the-art classifiers in view of their effectiveness for automatic sleep staging. In spite of the existence of a large number of these types of classifiers, to-this-date, no prior DNN-based approach has attempted sleep-stage classification using pediatric electroencephalographic (EEG) signals. In this paper, we propose a novel end-to-end classifier based on a multi-domain hybrid neural network (HNN-multi) approach consisting of a convolutional neural network and bidirectional long short-term memory for automatic sleep staging with pediatric scalp EEG recordings. To find effective temporal, spatial, and domain-specific conditions, we investigated noticeable changes in the classification performance corresponding to: 1) the length of input signals; 2) the number of channels; and 3) the types of input signals in the time and frequency domains. Our HNN-based classifier yielded the best performance metrics using 30-s time series in combination with an instantaneous frequency using a 19-channel, three-stage classification, with overall accuracy, F1 score, and Cohen's Kappa, equal to 92.21%, 0.90, and 0.88, respectively. We suggest that an effective combination of temporal and spatial time-domain clues with time-varying frequency domain information plays a pivotal role in pediatric, automatic sleep staging. Sufficiently reasonable performance of our HNN-based approach coping with the highly complicated pediatric EEG signatures hopefully sheds light on the clinical feasibility of the DNN-based automatic sleep staging for pediatric neurology.
- Published
- 2019
27. Learning-Based Instantaneous Drowsiness Detection Using Wired and Wireless Electroencephalography
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Jee-Eun Yoon, Inha Hwang, Hyun-Soo Choi, Siwon Kim, Chang-Ho Yun, Ho Bae, Seonwoo Min, Sungroh Yoon, and Dana Oh
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General Computer Science ,Computer science ,lapse ,Electroencephalography ,03 medical and health sciences ,0302 clinical medicine ,0502 economics and business ,medicine ,Wireless ,General Materials Science ,Drowsiness ,050210 logistics & transportation ,Learning classifier system ,medicine.diagnostic_test ,business.industry ,05 social sciences ,General Engineering ,Psychomotor vigilance task ,Pattern recognition ,Alertness ,wireless electroencephalography ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,Artificial intelligence ,business ,lcsh:TK1-9971 ,electroencephalography ,030217 neurology & neurosurgery - Abstract
Instantaneous drowsiness ( i.e., lapse or micro-sleep) during various activities such as driving or construction causes enormous socioeconomic losses. Thus, a virtuous cycle system that monitors a subject’s drowsiness can improve work efficiency and safety. We propose a novel framework to detect instantaneous drowsiness with only a two-second length of electroencephalography (EEG). To achieve reliable performance, we use multitaper power spectral density for feature extraction along with extreme gradient boosting as a machine learning classifier. In addition, we introduce a novel phenotype labeling of instantaneous drowsiness by combining both task dependent and independent measures of alertness (psychomotor vigilance task and electrooculography technique, respectively). The results show that our techniques outperform others used in previous studies. We also identified which spectral components ( $\theta $ , $\alpha $ , and $\gamma $ ) and channels (Fp1, Fp2, T3, T4, O1, O2, and electrocardiogram) play important roles in our drowsiness detection framework. To verify the applicability for a mobile environment, we implemented our framework on a wireless EEG, as well as on a wired EEG. We hereby present our successful results.
- Published
- 2019
28. 1H NMR toxicometabolomics following cisplatin-induced nephrotoxicity in male rats
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Kyu-Bong Kim, Jung Dae Lee, Sung Ha Ryu, Suhkmann Kim, Siwon Kim, and Ji Won Kim
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Cisplatin ,Urinalysis ,medicine.diagnostic_test ,Urinary system ,Urine ,010501 environmental sciences ,Pharmacology ,Toxicology ,030226 pharmacology & pharmacy ,01 natural sciences ,Nephrotoxicity ,Glutamine ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Betaine ,chemistry ,medicine ,Leucine ,0105 earth and related environmental sciences ,medicine.drug - Abstract
Cisplatin (CP) is an anti-cancer drug used for treatment of solid tumors, but the major adverse effect is drug-induced nephrotoxicity. The current study aimed to determine biomarkers that might predict nephrotoxicity induced by CP using serum or urinary proton nuclear magnetic resonance (1H NMR) spectral data in male Sprague-Dawley (S-D) rats. CP (0, 0.5 or 5 mg/kg) was intraperitoneally (i.p.) administered for single dose. Animals were sacrificed 2 days (D2) or 8 days (D8) after administration of CP in order to perform analysis of serum biochemistries and histopathologic examination. Urine samples were collected every 24 hr from pre-treatment to sacrifice. Serum and urinary 1H NMR spectral data revealed apparent differential clustering between control and CP-treated groups as evidenced by principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) in global and targeted profiling. The concentrations of endogenous serum metabolites, alanine, betaine, glucose, glutamine, lactate, and leucine were significantly increased on D2. Urinary concentrations of alanine, glucose, glycine, guanidinoacetate, acetate, and lactate were significantly elevated on D2 or D8, whereas concentrations of urinary metabolites, citrate and hippurate were significantly decreased on D2 or D8. The correlation of serum and urinary 1H NMR OPLS-DA with serum biochemistry and renal histopathologic changes suggests that 1H NMR urinalysis may be used to reliably predict or screen CP-induced nephrotoxicity. Data suggest that these altered endogenous metabolites might serve as specific biomarkers for CP-induced nephrotoxicity.
- Published
- 2019
29. Optimization of Vinyl Sulfone Derivatives as Potent Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) Activators for Parkinson’s Disease Therapy
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Seo Yeon Woo, Sang Moon Han, Jin Woo Kim, Jong Hyun Park, Chang-Ho Lee, Siwon Kim, Su Jeong Shin, Ae Nim Pae, Hyeon Jeong Kim, Jaeick Lee, Gyoonhee Han, Ki Duk Park, and Jiwon Choi
- Subjects
Vinyl Compounds ,Antioxidant ,Cell Survival ,NF-E2-Related Factor 2 ,Glutamate-Cysteine Ligase ,medicine.medical_treatment ,01 natural sciences ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,Cell Line, Tumor ,Drug Discovery ,medicine ,Animals ,Humans ,Sulfones ,Tyrosine ,030304 developmental biology ,EC50 ,chemistry.chemical_classification ,0303 health sciences ,Chemistry ,Dopaminergic ,Parkinson Disease ,Up-Regulation ,0104 chemical sciences ,Disease Models, Animal ,010404 medicinal & biomolecular chemistry ,Neuroprotective Agents ,Enzyme ,Biochemistry ,Cell culture ,Microsomes, Liver ,Microsome ,Molecular Medicine ,Lead compound ,Heme Oxygenase-1 - Abstract
We previously developed a novel series of vinyl sulfones as nuclear factor erythroid 2-related factor 2 (Nrf2) activators with therapeutic potential for Parkinson’s disease (PD). However, the previously developed lead compound (1) exhibited undesirable druglike properties. Here, we optimized vinyl sulfones by introducing nitrogen heterocycles to improve druglike properties. Among the synthesized compounds, 17e was the most promising drug candidate with good druglike properties. Compound 17e showed superior effects on Nrf2 activation in cell-based assays compared to compound 1 (17e: half-maximal effective concentration (EC50) = 346 nM; 1: EC50 = 530 nM). Compound 17e was further confirmed to induce expression of Nrf2-dependent antioxidant enzymes at both mRNA and protein levels. In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD, 17e significantly attenuated loss of tyrosine hydroxylase-immunopositive dopaminergic neurons, suppressed microglial activation, and alleviated PD-associa...
- Published
- 2018
30. Towards a Rigorous Evaluation of Time-series Anomaly Detection
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Siwon Kim, Kukjin Choi, Hyun-Soo Choi, Byunghan Lee, and Sungroh Yoon
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Methodology (stat.ME) ,FOS: Computer and information sciences ,Computer Science - Machine Learning ,Artificial Intelligence (cs.AI) ,Computer Science - Artificial Intelligence ,General Medicine ,Statistics - Methodology ,Machine Learning (cs.LG) - Abstract
In recent years, proposed studies on time-series anomaly detection (TAD) report high F1 scores on benchmark TAD datasets, giving the impression of clear improvements in TAD. However, most studies apply a peculiar evaluation protocol called point adjustment (PA) before scoring. In this paper, we theoretically and experimentally reveal that the PA protocol has a great possibility of overestimating the detection performance; that is, even a random anomaly score can easily turn into a state-of-the-art TAD method. Therefore, the comparison of TAD methods after applying the PA protocol can lead to misguided rankings. Furthermore, we question the potential of existing TAD methods by showing that an untrained model obtains comparable detection performance to the existing methods even when PA is forbidden. Based on our findings, we propose a new baseline and an evaluation protocol. We expect that our study will help a rigorous evaluation of TAD and lead to further improvement in future researches., Comment: 11 pages, 8 figures
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- 2021
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31. KDS2010, a newly developed reversible MAO-B inhibitor, as an effective therapeutic candidate for Parkinson’s disease
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Hyung Ho Yoon, Doo-Wan Cho, Sang Ryong Jeon, Young-Su Yang, Bo Ko Jang, Hyo Jung Song, C. Justin Lee, Sang-Wook Kim, Siwon Kim, Ki Duk Park, Su-Cheol Han, Jun Young Heo, Jong Hyun Park, Soo Jin Oh, Min-Ho Nam, and Jiwon Choi
- Subjects
Parkinson's disease ,business.industry ,MPTP ,Parkinsonism ,Selegiline ,Therapeutic effect ,Pharmacology ,medicine.disease ,Neuroprotection ,chemistry.chemical_compound ,chemistry ,In vivo ,Toxicity ,medicine ,business ,medicine.drug - Abstract
Background and PurposeMonoamine oxidase-B (MAO-B) is a long-standing therapeutic target for Parkinson’s disease (PD), however, previous clinical studies demonstrated discouraging effects of currently available irreversible MAO-B inhibitors. Since KDS2010, a novel, potent, selective, and reversible MAO-B inhibitor, has been developed, here we tested its therapeutic potential in animal models of PD.Experimental ApproachWe designed and synthesized α-aminoamide derivatives and compared the specificity to MAO-B and reversibility of each compound with KDS2010. To investigate the in vivo therapeutic effect, we used MPTP mouse model with two different regimes of 3-day administration (pre-treatment or post-treatment) and 30-day administration. We assessed the therapeutic potential using behavioral and immunohistochemical analyses. Additionally, the functional recovery by KDS2010 was tested in 6-hydroxydopamine-induced and A53T-alpha-synuclein overexpression models. Lastly, to validate the potential as a clinical drug candidate, we investigated the pharmacokinetics and toxicity of KDS2010 in non-human primates.Key ResultsKDS2010 showed the highest potency, specificity, and reversibility among the α-aminoamide derivatives, with high bioavailability (>100%) and BBB permeability. KDS2010 also showed significant neuroprotective and anti-neuroinflammatory effects in the nigrostriatal pathway, leading to an alleviation of MPTP-induced parkinsonism in all administration regimes. In particular, the therapeutic effect of KDS2010 was superior to selegiline, an irreversible MAO-B inhibitor. KDS2010 also showed a potent therapeutic effect in 6-hydroxydopamine and A53T models. Moreover, KDS2010 showed virtually no toxicity or side-effect in non-human primates.Conclusion and ImplicationsKDS2010 shows excellent therapeutic potential and safety in various PD animal models. KDS2010, therefore, could be a next-generation therapeutic candidate for PD.Representative SchematicWhat is already knownKDS2010 is a recently developed potent, selective, and reversible MAO-B inhibitor.MAO-B is critical for PD pathology through astrocytic GABA and H2O2 synthesis.What this study addsKDS2010 treatment dramatically recovers from PD-related pathology and motor deficit after pre- and post-treatment regimes in several animal models of PD.KDS2010 exhibits low toxicity and excellent pharmacokinetic profile in non-human primates.What is the clinical significance?KDS2010 is a safe and promising therapeutic candidate for Parkinson’s disease.Reversible MAO-B inhibitors could be more effective for treatment of Parkinson’s disease, overcoming the short-lived actions of irreversible MAO-B inhibitors.
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- 2020
32. Interpretation of NLP models through input marginalization
- Author
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Jihun Yi, Siwon Kim, Eunji Kim, and Sungroh Yoon
- Subjects
FOS: Computer and information sciences ,Interpretation (logic) ,Computer Science - Computation and Language ,Computer science ,business.industry ,Property (programming) ,Computer Science - Artificial Intelligence ,Sentiment analysis ,02 engineering and technology ,010501 environmental sciences ,computer.software_genre ,01 natural sciences ,Zero (linguistics) ,Artificial Intelligence (cs.AI) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,computer ,Value (mathematics) ,Computation and Language (cs.CL) ,Sentence ,Natural language processing ,0105 earth and related environmental sciences - Abstract
To demystify the "black box" property of deep neural networks for natural language processing (NLP), several methods have been proposed to interpret their predictions by measuring the change in prediction probability after erasing each token of an input. Since existing methods replace each token with a predefined value (i.e., zero), the resulting sentence lies out of the training data distribution, yielding misleading interpretations. In this study, we raise the out-of-distribution problem induced by the existing interpretation methods and present a remedy; we propose to marginalize each token out. We interpret various NLP models trained for sentiment analysis and natural language inference using the proposed method., Comment: 10 pages, 5 figures, to be published in the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP 2020)
- Published
- 2020
- Full Text
- View/download PDF
33. 1H NMR Based Metabolomics Studies of the Toxicity of Titanium Dioxide Nanoparticles in Zebrafish (Danio rerio)
- Author
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Ganesan Raja, Siwon Kim, Dahye Yoon, Changshin Yoon, and Suhkmann Kim
- Subjects
0301 basic medicine ,biology ,Chemistry ,Danio ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,03 medical and health sciences ,030104 developmental biology ,Metabolomics ,Toxicity ,Titanium dioxide nanoparticles ,Proton NMR ,0210 nano-technology ,Cytotoxicity ,Zebrafish ,Nuclear chemistry - Published
- 2017
34. A study on the effect of selected process parameters in a jet diffusion flame for Pt nanoparticle formation
- Author
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Haoran Yu, Justin Roller, Radenka Maric, Siwon Kim, and Tony Kwak
- Subjects
Quenching ,Materials science ,Mechanical Engineering ,Diffusion flame ,Order (ring theory) ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Volumetric flow rate ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Mechanics of Materials ,Propane ,Content (measure theory) ,General Materials Science ,Particle size ,0210 nano-technology - Abstract
Pt is used in many catalytic applications from three-way catalysts to fuel cells. Particle size and morphology are key parameters that influence the electrocatalytic activity. Flame synthesis is an efficient and continuous manufacturing route capable of producing Pt nanoparticles with desirable catalytic properties. In order to understand the effect of the forced oxidant, solvent composition, and quench rate on nanoparticle formation, a systematic study of process parameters using Pt was undertaken. Reactive spray deposition technology was used as the synthesis platform. In order to obtain a tight control of the Pt size, it was found that the fuel must contain a sufficient enthalpy of combustion and appropriate propane content. The fuel must be mixed adequately to form a turbulent diffusion flame and must create conditions where unwanted Pt coarsening cannot occur. From this study, the conditions that favor this morphology require an O2 flow rate setting of 6.89 L/min or higher, a propane content of 20 wt%, and no quenching. Electrochemical data show decreasing electrochemical surface area (75–36 m2/gPt), increasing mass activity (120–610 mA/mgPt), and increasing specific activity (150–1350 $$ \upmu {\text{A}}/ {\text{cm}}^{2} {_{\text{Pt}}} $$ ) with increasing oxidant flow.
- Published
- 2017
35. 1 H-NMR with Multivariate Analysis for Automobile Lubricant Comparison
- Author
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Siwon Kim, Dong-kye Lee, Changshin Yoon, Suhkmann Kim, and Dahye Yoon
- Subjects
Automotive engine ,Engineering ,business.industry ,010401 analytical chemistry ,Mechanical engineering ,Industrial Oils ,01 natural sciences ,Automotive engineering ,0104 chemical sciences ,Pathology and Forensic Medicine ,03 medical and health sciences ,0302 clinical medicine ,Genetics ,030216 legal & forensic medicine ,Lubricant ,business - Abstract
Identification of suspected automobile-related lubricants could provide valuable information in forensic cases. We examined that automobile lubricants might exhibit the chemometric characteristics to their individual usages. To compare the degree of clustering in the plots, we co-plotted general industrial oils that were highly dissimilar with automobile lubricants in additive compositions. 1 H-NMR spectroscopy was used with multivariate statistics as a tool for grouping, clustering, and identification of automobile lubricants in laboratory conditions. We analyzed automobile lubricants including automobile engine oils, automobile transmission oils, automobile gear oils, and motorcycle oils. In contrast to the general industrial oils, automobile lubricants showed relatively high tendencies of clustering to their usages. Our pilot study demonstrated that the comparison of known and questioned samples to their usages might be possible in forensic fields.
- Published
- 2017
36. 1H-NMR-based Metabolomics Studies of the Toxicity of Mesoporous Carbon Nanoparticles in Zebrafish (Danio rerio)
- Author
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Siwon Kim, Changshin Yoon, Suhkmann Kim, Dahye Yoon, and Ganesan Raja
- Subjects
0301 basic medicine ,biology ,Chemistry ,Danio ,Nanoparticle ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,Citric acid cycle ,03 medical and health sciences ,030104 developmental biology ,Metabolomics ,Biochemistry ,Toxicity ,Proton NMR ,Glycolysis ,0210 nano-technology ,Zebrafish - Abstract
Mesoporous carbon nanoparticles (MCNs) have been applied in a variety of drug/gene carriers. In addition to their potential benefits, many studies of their potential toxicity have been reported, showing the limitations of metabolic contextualization. In this study, we conducted 1H-nuclear magnetic resonance (NMR) profiling combined with statistical methods such as orthogonal partial least squares discriminant analysis and Pearson correlation analysis to assess metabolic alterations in the whole body of zebrafish (Danio rerio) in the presence of various concentrations of MCNs. The MCN exposure influenced numerous metabolites in energy metabolism (e.g., metabolites involved in glycolysis and tricarboxylic acid cycle) and disturbed the balance of neurotransmitters and osmoregulators. Our findings demonstrate the potential applicability of using a metabolomics approach to determine underlying metabolic disturbances caused by MCNs.
- Published
- 2017
37. 1H-NMR-based metabolomic studies of bisphenol A in zebrafish (Danio rerio)
- Author
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Dahye Yoon, Junghee Cho, Changshin Yoon, Heonho Lee, Siwon Kim, Suhkmann Kim, and Hyeonsoo Choi
- Subjects
0301 basic medicine ,endocrine system ,Metabolite ,Danio ,010501 environmental sciences ,medicine.disease_cause ,01 natural sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Metabolomics ,medicine ,Metabolome ,Inosine ,Zebrafish ,0105 earth and related environmental sciences ,biology ,urogenital system ,General Medicine ,biology.organism_classification ,Pollution ,Glutamine ,030104 developmental biology ,Biochemistry ,chemistry ,Environmental chemistry ,hormones, hormone substitutes, and hormone antagonists ,Oxidative stress ,Food Science ,medicine.drug - Abstract
Proton nuclear magnetic resonance (1H-NMR) spectroscopy was used to study the response of zebrafish (Danio rerio) to increasing concentrations of bisphenol A (4,4′-(propane-2,2-diyl)diphenol, BPA). Orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to detect aberrant metabolomic profiles after 72 h of BPA exposure at all levels tested (0.01, 0.1, and 1.0 mg/L). The OPLS-DA score plots showed that BPA exposure caused significant alterations in the metabolome. The metabolomic changes in response to BPA exposure generally exhibited nonlinear patterns, with the exception of reduced levels of several metabolites, including glutamine, inosine, lactate, and succinate. As the level of BPA exposure increased, individual metabolite patterns indicated that the zebrafish metabolome was subjected to severe oxidative stress. Interestingly, ATP levels increased significantly at all levels of BPA exposure. In the present study, we demonstrated the applicability of 1H-NMR-based metabolomi...
- Published
- 2017
38. Capacity Planning for Virtual Resource Management in Network Slicing
- Author
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Hyunseung Choo, Rajesh Challa, Syed M. Raza, and Siwon Kim
- Subjects
Computer science ,Event (computing) ,Distributed computing ,020206 networking & telecommunications ,02 engineering and technology ,Service provider ,Slicing ,Application lifecycle management ,Capacity planning ,Resource (project management) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Resource management ,Orchestration (computing) - Abstract
Network slicing is envisioned as one of the core enablers for 5G. It empowers service providers to multiplex their physical infrastructure over multiple logical networks. Slice orchestration performs lifecycle management and virtual resource management of a network slice. Slice capacity planning, one of the key responsibilities of slice orchestration faces two major challenges: (i) minimum slice capacity estimation for a given slice configuration, and (ii) lack of simple network slicing supported open source solutions due to which the research and development of slice resource orchestration activities are hit adversely. The feature-rich existing solutions have significantly high learning curve. This paper addresses these two issues. We present a probabilistic model for slice capacity planning and propose a simple orchestration-centric discrete event simulator to develop and evaluate minimum slice capacity requirement. The results taken on our custom simulator show around 96% of resource utilization, and have less than 5% relative error when compared with the theoretical model.
- Published
- 2019
39. Development and optimization of halogenated vinyl sulfones as Nrf2 activators for the treatment of Parkinson’s disease
- Author
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Siwon Kim, Hyeon Jeong Kim, Byung Eun Kim, Elijah Hwejin Lee, Jong Seok Yoo, Yong Sup Lee, Hyeon Ji Kim, Ki Duk Park, Jiwon Choi, and Jong Hyun Park
- Subjects
Male ,Antioxidant ,Halogenation ,Cell Survival ,NF-E2-Related Factor 2 ,medicine.medical_treatment ,Pharmacology ,medicine.disease_cause ,01 natural sciences ,Cell Line ,Proinflammatory cytokine ,Mice ,Structure-Activity Relationship ,03 medical and health sciences ,chemistry.chemical_compound ,Drug Development ,Drug Discovery ,medicine ,Animals ,Humans ,Sulfones ,030304 developmental biology ,0303 health sciences ,Dose-Response Relationship, Drug ,Molecular Structure ,010405 organic chemistry ,GCLM ,MPTP ,Organic Chemistry ,Parkinson Disease ,General Medicine ,KEAP1 ,0104 chemical sciences ,Mice, Inbred C57BL ,GCLC ,chemistry ,Signal transduction ,Oxidative stress - Abstract
The Kelch-like ECH-associated protein 1 (Keap1)-Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays a pivotal role in the cellular defense system against oxidative stress by inducing antioxidant and anti-inflammatory effects. We previously developed Nrf2 activators that potentially protect the death of dopaminergic (DAergic) neuronal cells against oxidative stress in Parkinson’s disease (PD). In this study, we designed and synthesized a class of halogenated vinyl sulfones by inserting halogens and pyridine to maximize Nrf2 activation efficacy. Among the synthesized compounds, (E)-3-chloro-2-(2-((2-chlorophenyl)sulfonyl)vinyl)pyridine (9d) significantly exhibited potent Nrf2 activating efficacy (9d: EC50 = 26 nM) at least 10-fold compared with the previous developed compounds (1 and 2). Furthermore, treating with 9d remarkably increased Nrf2 nuclear translocation and Nrf2 protein levels in microglial BV-2 cells. 9d was shown to induce the expression of antioxidant response genes HO-1, GCLC, GCLM, and SOD-1 at both the mRNA and protein levels and suppress proinflammatory cytokines and enzymes. Also, 9d remarkably protected DAergic neurons and restored the PD-associated motor dysfunction in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model.
- Published
- 2021
40. 1H-NMR-based metabolomic study on toxicity of methomyl and methidathion in fish
- Author
-
Dahye Yoon, Minji Lee, Changshin Yoon, Suhkmann Kim, and Siwon Kim
- Subjects
Male ,0301 basic medicine ,Insecticides ,Proton Magnetic Resonance Spectroscopy ,Methomyl ,Cyprinidae ,Methidathion ,Toxicology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Betaine ,Metabolomics ,Toxicity Tests ,Animals ,Choline ,Pesticides ,Zebrafish ,Behavior, Animal ,Organothiophosphorus Compounds ,General Medicine ,Pesticide ,Pollution ,Acetylcholinesterase ,Oxidative Stress ,030104 developmental biology ,chemistry ,Biochemistry ,Multivariate Analysis ,Toxicity ,Female ,Water Pollutants, Chemical ,030217 neurology & neurosurgery ,Food Science - Abstract
A 1H-nuclear magnetic resonance (NMR) spectroscopy with multivariate analysis was applied to detect the toxicity of antiacetylcholinesterase insecticides, methomyl (methyl (1E)-N-(methylcarbamoyloxy)ethanimidothioate) and methidathion (3-(dimethoxyphosphinothioyl sulfanylmethyl)-5-methoxy-1,3,4-thiadiazol-2-one), using zebrafish (Danio rerio) and Chinese bleak (Aphyocypris chinensis). Generally, methomyl and methidathion have been believed not to highly accumulate in fish tissues. However, these pesticides showed their toxicity by altering patterns of whole-body metabolites in neurotransmitter balance, energy metabolism, oxidative stress, and muscle maintenance in low concentrations. We used Pearson correlation analysis to contextualize the metabolic markers in pesticide treated groups. We observed that the positive correlations of choline with acetate and betaine in untreated control were shifted to null correlations showing acetylcholinesterase specific toxicity. This research demonstrated the a...
- Published
- 2016
41. Metabolic profiling of antioxidant supplement with phytochemicals using plasma 1H NMR-based metabolomics in humans
- Author
-
Siwon Kim, Ji-Won Kim, Oran Kwon, Kyu Bong Kim, Hyun Jun Jang, Suhkmann Kim, You Jin Kim, and Sung Ha Ryu
- Subjects
0301 basic medicine ,Antioxidant ,Folate cycle ,DNA damage ,medicine.medical_treatment ,Medicine (miscellaneous) ,medicine.disease_cause ,Antioxidative supplement ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Metabolomics ,Betaine ,medicine ,Choline ,TX341-641 ,chemistry.chemical_classification ,Reactive oxygen species ,Nutrition and Dietetics ,Nutrition. Foods and food supply ,Metabolic pathway ,030104 developmental biology ,Biochemistry ,chemistry ,Oxidative stress ,030220 oncology & carcinogenesis ,Food Science - Abstract
Aging and age-related diseases in humans are mainly caused by oxidative stress through over-production of reactive oxygen species (ROS). In our previous study, multi-micronutrient supplement containing antioxidants and phytochemicals (MP) resulted in higher antioxidative activity by increasing plasma folate with resistance to DNA damage and LDL oxidation to subjects. In this study, plasma samples were analysed for metabolomics study using 1 H NMR. The metabolic profiles before MP supplementation and after 8-week MP supplementation were clearly separated based on multivariant analyses of principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). Twenty-seven metabolites from variable importance plots were screened before MP supplementation and after 8-week MP supplementation. The 27 metabolites had significantly increased levels of betaine but significantly decreased levels of choline, serine, and threonine after MP supplementation. These results suggested that MP supplementation could activate folate cycle to increase resistance to DNA damages.
- Published
- 2016
42. Metabolic responses in zebrafish (Danio rerio) exposed to zinc and cadmium by nuclear magnetic resonance -based metabolomics
- Author
-
Suhkmann Kim, Dahye Yoon, Minji Lee, Changshin Yoon, and Siwon Kim
- Subjects
0301 basic medicine ,Metabolite ,Danio ,010501 environmental sciences ,01 natural sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Metabolomics ,Nuclear magnetic resonance ,medicine ,Inosine ,Zebrafish ,Ecology, Evolution, Behavior and Systematics ,Hypoxanthine ,0105 earth and related environmental sciences ,General Environmental Science ,Ecology ,biology ,Nuclear magnetic resonance spectroscopy ,Glutathione ,biology.organism_classification ,030104 developmental biology ,Biochemistry ,chemistry ,General Earth and Planetary Sciences ,medicine.drug - Abstract
Heavy metals are common marine and soil pollutants that are mainly the result of industrial activity, and are a threat to the environment and human health. In this study, 1H nuclear magnetic resonance (NMR)-based metabolomics was applied to adult Danio rerio to monitor the metabolic change as a response to ZnCl2 and CdCl2 exposure at different concentrations for 72 h. NMR spectroscopy was used to identify and quantify the metabolites extracted from D. rerio. The metabolite profiles of the control and heavy metal exposed group were classified by partial least squares – discriminant analysis (PLS-DA) analysis, and potential contaminant-specific biomarkers were suggested. For the ZnCl2-exposed zebrafish, the levels of ATP, aspartate and NAD+ were increased, whereas the levels of formate, inosine, hypoxanthine and succinate decreased. In addition, the CdCl2-exposed zebrafish showed an increase in the levels of ATP and formate and a decrease in the levels of glutamate, inosine and glutathione. Overall,...
- Published
- 2016
43. Prediction of Indolent Breast Cancer with Favorable Prognostic Factors by Metabolic Profiling Using In Vivo and Ex Vivo MR Metabolomics
- Author
-
Dahye Yoon, Suhkmann Kim, Siwon Kim, Joo Hee Cha, Hyeon-Man Baek, Hak Hee Kim, and Hee Jung Shin
- Subjects
Oncology ,medicine.medical_specialty ,Univariate analysis ,Multivariate analysis ,business.industry ,Estrogen receptor ,medicine.disease ,Atomic and Molecular Physics, and Optics ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,Breast cancer ,In vivo ,030220 oncology & carcinogenesis ,Internal medicine ,medicine ,business ,Lymph node ,Pathological ,Ex vivo - Abstract
To evaluate whether metabolic profiles obtained using high-resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS) and total choline-containing compound (tCho) on in vivo MRS could predict indolent tumors based on highly favorable prognostic factors. We analyzed 50 frozen tissue samples from 50 patients (mean 46.4 years, range 29–72 years) with breast cancer using HR MAS MRS. In vivo single-voxel MRS analyses were also performed on these patients preoperatively. We defined estrogen receptor (ER)-positive tumors with a low histological grade, low Ki-67-positivity (
- Published
- 2016
44. Discovery of urinary metabolomic biomarkers for early detection of acute kidney injury
- Author
-
Kyu-Bong Kim, Yoon Gyoon Kim, A Jin Won, Siwon Kim, Suhkmann Kim, Kyeong Seok Kim, Sam Kacew, Byung Mu Lee, Hyung Sik Kim, Jee H. Jung, and Wahn Soo Choi
- Subjects
Male ,0301 basic medicine ,medicine.medical_specialty ,Biopsy ,Proton Magnetic Resonance Spectroscopy ,Urinary system ,Urine ,Lipocalin ,Kidney ,03 medical and health sciences ,chemistry.chemical_compound ,Internal medicine ,Animals ,Metabolomics ,Medicine ,Molecular Biology ,Blood urea nitrogen ,Creatinine ,business.industry ,Acute kidney injury ,Kidney metabolism ,Acute Kidney Injury ,medicine.disease ,Rats ,030104 developmental biology ,Endocrinology ,medicine.anatomical_structure ,Liver ,ROC Curve ,chemistry ,Immunology ,Metabolome ,business ,Biomarkers ,Biotechnology - Abstract
The discovery of new biomarkers for early detection of drug-induced acute kidney injury (AKI) is clinically important. In this study, sensitive metabolomic biomarkers identified in the urine of rats were used to detect cisplatin-induced AKI. Cisplatin (10 mg kg(-1), i.p.) was administered to Sprague-Dawley rats, which were subsequently euthanized after 1, 3 or 5 days. In cisplatin-treated rats, mild histopathological alterations were noted at day 1, and these changes were severe at days 3 and 5. Blood urea nitrogen (BUN) and serum creatinine (SCr) levels were significantly increased at days 3 and 5. The levels of new urinary protein-based biomarkers, including kidney injury molecule-1 (KIM-1), glutathione S-transferase-α (GST-α), tissue inhibitor of metalloproteinase-1 (TIMP-1), vascular endothelial growth factor (VEGF), calbindin, clusterin, neutrophil, neutrophil gelatinase-associated lipocalin (NGAL), and osteopontin, were significantly elevated at days 3 and 5. Among urinary metabolites, trigonelline and 3-indoxylsulfate (3-IS) levels were significantly decreased in urine collected from cisplatin-treated rats prior to histological kidney damage. However, carbon tetrachloride (CCl4), a hepatotoxicant, did not affect these urinary biomarkers. Trigonelline is closely associated with GSH depletion and results in insufficient antioxidant capacity against cisplatin-induced AKI. The predominant cisplatin-induced AKI marker appeared to be reduced in urinary 3-IS levels. Because 3-IS is predominantly excreted via active secretion in proximal tubules, a decrease is indicative of tubular damage. Further, urinary excretion of 3-IS levels was markedly reduced in patients with AKI compared to normal subjects. The area under the curve receiver operating characteristics (AUC-ROC) for 3-IS was higher than for SCr, BUN, lactate dehydrogenase (LDH), total protein, and glucose. Therefore, low urinary or high serum 3-IS levels may be more useful for early detection of AKI than conventional biomarkers.
- Published
- 2016
45. XGBoost-Based Instantaneous Drowsiness Detection Framework Using Multitaper Spectral Information of Electroencephalography
- Author
-
Jee Eun Yoon, Hyun-Soo Choi, Sungroh Yoon, Jung Eun Oh, Chang-Ho Yun, Jung Ah Park, and Siwon Kim
- Subjects
Learning classifier system ,medicine.diagnostic_test ,business.industry ,Computer science ,Feature extraction ,Psychomotor vigilance task ,Spectral density ,Pattern recognition ,Electrooculography ,Electroencephalography ,03 medical and health sciences ,Alertness ,0302 clinical medicine ,Multitaper ,medicine ,030212 general & internal medicine ,Artificial intelligence ,business ,030217 neurology & neurosurgery - Abstract
The socioeconomic losses caused by extreme daytime drowsiness are enormous in these days. Hence, building a virtuous cycle system is necessary to improve work efficiency and safety by monitoring instantaneous drowsiness that can be used in any environment. In this paper, we propose a novel framework to detect extreme drowsiness using a short time segment (~ 2 s) of EEG which well represents immediate activity changes depending on a person's arousal, drowsiness, and sleep state. To develop the framework, we use multitaper power spectral density (MPSD) for feature extraction along with extreme gradient boosting (XGBoost) as a machine learning classifier. In addition, we suggest a novel drowsiness labeling method by combining the advantages of the psychomotor vigilance task and the electrooculography technique. By experimental evaluation, we show that the adopted MPSD and XGB techniques outperform other techniques used in previous studies. Finally, we identify that spectral components (theta, alpha, and gamma) and channels (Fp1, Fp2, T3, T4, O1, and O2) play an important role in our drowsiness detection framework, which could be extended to mobile devices.
- Published
- 2018
46. Hybrid Noise Reduction for Audio Captured by Drones
- Author
-
Duc Tai Le, Hyunseung Choo, Hyohoon Ahn, Siwon Kim, and Thien Binh Dang
- Subjects
Similarity (geometry) ,business.industry ,Computer science ,Noise reduction ,020206 networking & telecommunications ,02 engineering and technology ,Broadcasting ,Signal ,Drone ,030507 speech-language pathology & audiology ,03 medical and health sciences ,Noise ,Spectral subtraction ,0202 electrical engineering, electronic engineering, information engineering ,Computer vision ,Artificial intelligence ,0305 other medical science ,business ,Active noise control - Abstract
Recently, advances in technology have reduced the sizes, lowered prices, and increased commercial use of drones. In the market, drones have become an inexpensive and accessible way to accomplish many tasks such as filming, surveillance, agriculture, delivery, and broadcasting. Such applications typically require a video recording for their operations. However, due to the noise generated by propellers and rotors of a drone, the quality of sound in a video recorded by the drone is quite limited. In order to solve the noise problem of drones, this paper proposes a novel hybrid noise reduction technique combining Active Noise Control and Spectral subtraction methods. Experimental results show that the proposed technique produces a speech signal with up to 67.5% similarity to the original signal. It outperforms Active Noise Control and Spectral Subtraction with similarities of 53.1% and 39.6%, respectively.
- Published
- 2018
47. The effect of binder content on the performance of a high temperature polymer electrolyte membrane fuel cell produced with reactive spray deposition technology
- Author
-
Yang Wang, Timothy D. Myles, Dongwook Kwak, H.Russel Kunz, Siwon Kim, and Radenka Maric
- Subjects
chemistry.chemical_classification ,Materials science ,General Chemical Engineering ,chemistry.chemical_element ,Polymer ,Electrolyte ,Electrochemistry ,Catalysis ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Organic chemistry ,Platinum ,Dispersion (chemistry) ,Carbon ,Phosphoric acid - Abstract
The effects of polytetrafluoroethylene (PTFE) binder content in the catalyst layer of high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) utilizing phosphoric acid doped Advent TPS® polymer electrolyte membranes (pyridine bearing aromatic polyethers, TPS) has been investigated in terms of both hydrogen/oxygen and hydrogen/air performance. The anode and cathode gas diffusion electrodes (GDE) were fabricated with different PTFE/carbon weight ratios by a flame based process known as the Reactive Spray Deposition Technology (RSDT) method in order to increase the active platinum (Pt) surface area, with a goal of decreasing overall Pt levels to a total loading of 0.1 mg cm−2. The electrodes, prepared with different amounts of PTFE binder, have been tested in a single cell, with a 25 cm2 geometric area, under an operating temperature range of 160–200 °C. Tests measuring the Pt nanoparticle dispersion on the carbon supports, the pore size distribution, and the electrochemical surface area of the catalyst layer were also performed. The best cell performance was achieved with PTFE/carbon weight ratio of 0.9 over the entire range of operating temperatures. This optimal PTFE binder content resulted in well-developed Pt dispersion on the carbon support and small, uniformly sized pores which develop ideal capillary forces for distributing the phosphoric acid electrolyte evenly throughout the catalyst layer. This led to a high number of triple phase boundaries and maximized Pt utilization.
- Published
- 2015
48. L'intimité entre le sujet et le monde dans les paysages poétiques : chez Claudel et Supervielle
- Author
-
Siwon Kim
- Subjects
General Medicine - Published
- 2015
49. Synthesis and evaluation of biaryl derivatives for structural characterization of selective monoamine oxidase B inhibitors toward Parkinson's disease therapy
- Author
-
Hyeon Jeong Kim, Ae Nim Pae, Yong Sun Bahn, Ye Rim Lee, Jong Hyun Park, Gyoonhee Han, Su Jeong Shin, Bo Ko Jang, Yong Sup Lee, Siwon Kim, Ki Duk Park, Seul Ki Yeon, and Jiwon Choi
- Subjects
0301 basic medicine ,Male ,Monoamine Oxidase Inhibitors ,Stereochemistry ,Clinical Biochemistry ,Pharmaceutical Science ,Biochemistry ,03 medical and health sciences ,chemistry.chemical_compound ,Mice ,Structure-Activity Relationship ,0302 clinical medicine ,Drug Discovery ,medicine ,Benzene Derivatives ,Moiety ,Animals ,Humans ,Molecular Biology ,IC50 ,Monoamine Oxidase ,Safinamide ,Tyrosine hydroxylase ,Dose-Response Relationship, Drug ,Molecular Structure ,Aryl ,Organic Chemistry ,Selegiline ,Parkinson Disease ,Mice, Inbred C57BL ,Disease Models, Animal ,030104 developmental biology ,chemistry ,1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine ,Molecular Medicine ,Amine gas treating ,Monoamine oxidase B ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Benzyloxyphenyl moiety is a common structure of highly potent, selective and reversible inhibitors of monoamine oxidase B (MAO-B), safinamide and sembragiline. We synthesized 4-(benzyloxy)phenyl and biphenyl-4-yl derivatives including halogen substituents on the terminal aryl unit. In addition, we modified the carbon linker between amine group and the biaryl linked unit. Among synthesized compounds, 12c exhibited the most potent and selective MAO-B inhibitory effect (hMAO-B IC50: 8.9 nM; >10,000-fold selectivity over MAO-A) as a competitive inhibitor. In addition, 12c showed greater MAO-B inhibitory activity and selectivity compared to well-known MAO-B inhibitors such as selegiline, safinamide and sembragiline. In the MPTP-induced mouse model of Parkinson’s disease (PD), 12c significantly protected the tyrosine hydroxylase (TH)-immunopositive DAergic neurons and attenuated the PD-associated behavioral deficits. This study suggests characteristic structures as a MAO-B inhibitor that may provide a good insight for the development of therapeutic agents for PD.
- Published
- 2017
50. Magnetic resonance metabolic profiling of estrogen receptor-positive breast cancer: correlation with currently used molecular markers
- Author
-
Eun Kyung Kim, Suhkmann Kim, Ja Seung Koo, Siwon Kim, Vivian Youngjean Park, Dahye Yoon, Min Jung Kim, and Ji Soo Choi
- Subjects
0301 basic medicine ,Oncology ,Pathology ,medicine.medical_specialty ,Multivariate analysis ,Estrogen receptor ,ER-positive ,03 medical and health sciences ,0302 clinical medicine ,Breast cancer ,breast cancer ,Statistical significance ,Internal medicine ,Biopsy ,Medicine ,luminal ,Univariate analysis ,medicine.diagnostic_test ,business.industry ,HR-MAS MRS (high-resolution magic angle spinning magnetic resonance spectroscopy) ,Magnetic resonance imaging ,medicine.disease ,030104 developmental biology ,030220 oncology & carcinogenesis ,Biomarker (medicine) ,biomarker ,business ,Research Paper - Abstract
Estrogen receptor (ER)-positive breast cancers overall have a good prognosis, however, some patients suffer relapses and do not respond to endocrine therapy. The purpose of this study was to determine whether there are any correlations between high-resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) metabolic profiles of core needle biopsy (CNB) specimens and the molecular markers currently used in patients with ER-positive breast cancers. The metabolic profiling of CNB samples from 62 ER-positive cancers was performed by HR-MAS MRS. Metabolic profiles were compared according to human epidermal growth factor receptor 2 (HER2) and Ki-67 status, and luminal type, using the Mann-Whitney test. Multivariate analysis was performed with orthogonal projections to latent structure-discriminant analysis (OPLS-DA). In univariate analysis, the HER2-positive group was shown to have higher levels of glycine and glutamate, compared to the HER2-negative group (P
- Published
- 2017
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