Search

Most studies related to hemp are focused on Cannabidiol (CBD) and Tetrahydrocannabinol (THC); however, up to 120 types of phytocannabinoids are present in hemp. Hemp leaves contain large amounts of Cannabidiolic acid (CBDA) and Tetrahydrocannabinolic acid (THCA), which are acidic variants of CBD and THC and account for the largest proportion of CBDA. In recent studies, CBDA exhibited anti-hyperalgesia and anti-inflammatory effects. THCA also showed anti-inflammatory and neuroprotective effects that may be beneficial for treating neurodegenerative diseases. CBDA and THCA can penetrate the blood–brain barrier (BBB) and affect the central nervous system. The purpose of this study was to determine whether CBDA and THCA ameliorate Alzheimer’s disease (AD)-like features in vitro and in vivo. The effect of CBDA and THCA was evaluated in the Aβ1–42-treated mouse model. We observed that Aβ1–42-treated mice had more hippocampal Aβ and p-tau levels, pathological markers of AD, and loss of cognitive function compared with PBS-treated mice. However, CBDA- and THCA-treated mice showed decreased hippocampal Aβ and p-tau and superior cognitive function compared with Aβ1–42-treated mice. In addition, CBDA and THCA lowered Aβ and p-tau levels, alleviated calcium dyshomeostasis, and exhibited neuroprotective effects in primary neurons. Our results suggest that CBDA and THCA have anti-AD effects and mitigate memory loss and resilience to increased hippocampal Ca2+, Aβ, and p-tau levels. Together, CBDA and THCA may be useful therapeutic agents for treating AD.

Several studies have been conducted on energy harvesting, which involves conversion of unused environmental energy into a power source. More than half of the energy consumed is wasted as heat. Therefore, attempts are being made to increase energy efficiency by effectively utilizing the waste heat as renewable energy. In this study, we focused on the time-varying waste heat source and fabricated lead lanthanum stannate zirconate titanate (PLZST) ceramics, which are pyroelectric materials. The electrical properties and power densities of the PLZSTs with five different compositional ratios of Zr and Sn were evaluated as functions of temperature. As the proportion of Zr increased, both the maximum dielectric constant and the maximum power density at each composition ratio shifted to higher temperatures. By controlling the Zr:Sn ratio in PLZSTs, power densities of more than 8 mW/cm3 were obtained over a wide temperature range of 140–200°C. In addition, power densities of more than 10 mW/cm3 were obtained between 150°C and 180°C. Therefore, we observed that PLZST is a promising material for the recovery of power from low-grade heat sources below 200°C.

Micro-sized segregated liquid crystals (MSLCs) surrounded by a polymer medium can be used for haze film applications. When incident light passes through the MSLC film, the microsized particles act as light scattering centers. In this study, the results of the addition of a multi-functional acrylate to a commercial thiol-ene prepolymer system, as well as the morphology of (LC) droplets, fractal dimension (D), and the optical haze performance of the micro-sized segregated LCs formed by UV-initiated photopolymerization, are reported. With increasing fraction of the multi-functional acrylate within the host polymer matrix, the small scattering centers (LC droplets) also increase, giving rise to a large optical haze in the prepared film. The optical haze can be characterized by the D of the associated LC droplet morphology in the films. The optical haze and D exhibit a strong correlation; thus, a qualitative prediction of the optical haze is possible via geometric fractal analysis.

Whitening research is of particular interest in the cosmetics market. The main focus of whitening research is on melanogenesis inhibition through tyrosinase activity. The mechanism of melanogenesis is involved with tyrosinase activity and p-PKC signaling. In this study, we used Momordica cochinchinensis (Lour.) spreng, a tropical fruit found throughout Southeast Asia, to investigate the inhibitory effect of melanogenesis. M. cochinchinensis contains a high concentration of polyphenols, flavonoids, and unsaturated fatty acids, which might be related to antioxidant activity. This study aimed to determine whether M. cochinchinensis extracts inhibit melanin synthesis in melan-A cells by inhibiting tyrosinase activity and p-PKC signaling. M. cochinchinensis was divided into pulp and aril and extracted under various conditions, and it was confirmed that all pulp and aril extracts have high contents of both phenols and flavonoids. Melan-A cells were treated with PMA for three days to induce melanin synthesis. After PMA treatment, M. cochinchinensis extracts were added to cultured media in a dose-dependent manner. Melanin contents and MTS were used to determine the amount of melanin in live cells. M. cochinchinensis extracts were evaluated for their effects on tyrosinase activity and p-PKC signaling pathways by Western blotting. It was found that M. cochinchinensis extract treatment decreased the amount of melanin and suppressed p-PKC expression. Additionally, tyrosinase activity was reduced after M. cochinchinensis extract treatment in a dose-dependent manner. Therefore, it was concluded that M. cochinchinensis could be used in antimelanogenesis and functional cosmetic materials to improve whitening.

Atherosclerotic plaques consist mostly of smooth muscle cells (SMC), and genes that influence SMC biology can modulate coronary artery disease (CAD) risk. Allelic variation at 15q22.33 has been identified by genome-wide association studies to modify the risk of CAD, and is associated with expression of SMAD3 in SMC, but the mechanism by which this gene modifies CAD risk remains poorly understood. SMC-specific deletion of Smad3 in a murine atherosclerosis model resulted in greater plaque burden, more positive remodeling, and increased vascular calcification. Single-cell transcriptomic analyses revealed that loss of Smad3 altered SMC transition cell state toward two fates: a novel SMC phenotype that governs both vascular remodeling and recruitment of inflammatory cells, as well as a chondromyocyte fate. The remodeling population was marked by uniquely high Mmp3 and Cxcl12 expression, and its appearance correlated with higher risk plaque features such as increased positive remodeling and macrophage content. Further, investigation of transcriptional mechanisms by which Smad3 alters SMC cell fate revealed novel roles for Hox and Sox transcription factors whose direct interaction with Smad3 regulate an extensive transcriptional program balancing remodeling and vascular extracellular matrix with significant implications for atherosclerotic and Mendelian aortic aneurysmal diseases. Together, these data suggest that Smad3 expression in SMC inhibits the emergence of specific SMC phenotypic transition cells that mediate adverse plaque features, including positive remodeling, monocyte recruitment, and vascular calcification.

The transient receptor potential vanilloid 1 (TRPV1) protein is a pain receptor that elicits a hot sensation when an organism eats the capsaicin of red chili peppers. This calcium (Ca2+)-permeable cation channel is mostly expressed in the peripheral nervous system sensory neurons but also in the central nervous system (e.g. hippocampus and cortex). Preclinical studies found that TRPV1 mediates behaviors associated with anxiety and depression. Loss of TRPV1 functionality increases expression of genes related to synaptic plasticity and neurogenesis. Thus, we hypothesized that TRPV1 deficiency may modulate Alzheimer’s disease (AD). We generated a triple-transgenic AD mouse model (3xTg-AD+/+) with wild-type (TRPV1+/+), hetero (TRPV1+/−) and knockout (TRPV1−/−) TRPV1 to investigate the role of TRPV1 in AD pathogenesis. We analyzed the animals’ memory function, hippocampal Ca2+ levels and amyloid-β (Aβ) and tau pathologies when they were 12 months old. We found that compared with 3xTg-AD−/−/TRPV1+/+ mice, 3xTg-AD+/+/TRPV1+/+ mice had memory impairment and increased levels of hippocampal Ca2+, Aβ and total and phosphorylated tau. However, 3xTg-AD+/+/TRPV1−/− mice had better memory function and lower levels of hippocampal Ca2+, Aβ, tau and p-tau, compared with 3xTg-AD+/+/TRPV1+/+ mice. Examination of 3xTg-AD-derived primary neuronal cultures revealed that the intracellular Ca2+ chelator BAPTA/AM and the TRPV1 antagonist capsazepine decreased the production of Aβ, tau and p-tau. Taken together, these results suggested that TRPV1 deficiency had anti-AD effects and promoted resilience to memory loss. These findings suggest that drugs or food components that modulate TRPV1 could be exploited as therapeutics to prevent or treat AD.

A modular multilevel converter (MMC) is regarded as a promising topology in high-voltage direct current systems. However, the MMC consists of numerous submodules (SMs) and switching devices, which lead to a considerable switching loss, and increased cost and size of the heat sink. To mitigate these issues, this paper presents a novel modulation method composed of fundamental frequency modulation (FFM) and multicarrier-based sinusoidal pulsewidth modulation schemes. The main purpose of this modulation method is the reduction of switching loss while maintaining good harmonic performance. However, the FFM scheme leads to the unbalanced capacitor voltage of each SM in the MMC. Accordingly, this paper additionally proposes the rotation method and selective voltage balancing control for SMs to ensure effective performance of the method. Simulation and experimental results verify the effectiveness and performance of the proposed modulation scheme through switching loss and spectral analyses.

Compositional generalization is the ability to generalize systematically to a new data distribution by combining known components. Although humans seem to have a great ability to generalize compositionally, state-of-the-art neural models struggle to do so. In this work, we study compositional generalization in classification tasks and present two main contributions. First, we study ways to convert a natural language sequence-to-sequence dataset to a classification dataset that also requires compositional generalization. Second, we show that providing structural hints (specifically, providing parse trees and entity links as attention masks for a Transformer model) helps compositional generalization., Comment: Accepted as a short paper at ACL 2021

This paper is about the development of the real-time direct current (DC) network analysis applications for the operation of DC power systems. The applications are located in the central energy management system (EMS) and provide the operator with the optimal solution for operation in real time. Developed DC applications are not limited by voltage level. Applications can be used at all DC voltage levels such as low voltage, medium voltage and high voltage. A program configuration and sequence for analyzing the DC distribution system are suggested. Algorithms of each program are presented and the differences when compared with the processes of the applications of the existing alternating current (AC) systems are analyzed. The DC grid demonstration site at the Korea Electric Power Corporation (KEPCO) power testing center is introduced. The details of EMS and applications installation are described. The developed DC applications were installed in the EMS of the demonstration site and verification tests have been carried out. The configuration of the test scenario for testing the voltage control of the DC network is described. The voltage control result is analyzed and the measured data and the results of the applications are verified for compatibility by comparing them with the results of an off-line simulation tool. Finally, the future direction of the development of technology for the operation of the DC grid is introduced.

This paper presents an optimized switching strategy to reduce the dc-link ripple current for three-level photovoltaic (PV) inverters. The large electrolytic capacitors are commonly used for the dc link of power electronics applications to stabilize the dc-link voltage. The most important factor of designing the dc-link capacitor is the allowable current ripple. The over-ripple current flowing through the capacitor causes a high heat loss, shortened lifespan, low stability, and reliability. The proposed switching scheme selects voltage vectors and reconfigures dwelling order of the vectors to reduce the capacitor ripple current. This switching method is able to extend the lifetime of the dc-link capacitors by simple software programming. In addition, this switching method reduces the common-mode voltage and leakage current that represent high reliability and safety of the system. The effectiveness of the proposed method is verified with simulations and experimental results.

We describe a novel synchronous surface tailoring to form thin and uniform carbon coating layers and simultaneously induce an in-situ phase transition from a layered to spinel-like phase on the surfaces of Li-rich layered oxide (LLOs) particles by the thermal decomposition of 2,3-dihydroxynaphthalene (DN). The Li2MnO3 component in pristine LLO is not affected during carbon coating, but the coordination numbers of the Co ions and the Co O bonds in the LiTMO2 phase are diminished during carbon coating, implying that the formation of a spinel-like phase in LLO after carbon coating begins at the LiTMO2 with little variation in the Li2MnO3. As a result, the optimized DN (0.2 wt%)-coated LLO cathode material shows superb electrochemical properties owing to the formation of uniform carbon coating layers and the layered-to spinel-phase transition on the surfaces of the LLO particles, which improves the surface stability, electronic conductivity, and Li-ion kinetics in the LLO.

In this paper, a novel buck–boost ac–ac converter is proposed. The basic switching unit of the proposed converter is a unidirectional buck circuit; therefore, it has no shoot-through worries. It can achieve safe commutation without using RC snubbers or soft commutation strategies. It can be implemented with power MOSFETs without their body diodes conducting and, for current freewheeling external diodes, can be used to minimize the reverse recovery issues and related loss. It has a bipolar voltage gain with both inverting and non-inverting operations. The non-inverting operation can be used to compensate voltage sag, and inverting operation can be used to compensate voltage swell. Therefore, the proposed converter as a dynamic voltage restorer is capable of compensating for both voltage sag and swell in a wide range. The detailed theoretical analysis followed by detailed experimental results of a 300-W prototype converter is provided.

This paper analyzes the combination in a cascaded H-bridge multilevel inverter (CHBI) based on transformers with the different turn ratios for increasing the voltage level and proposes the switching method for achieving the output voltage distribution among H-bridge cells (HBCs). The transformers used in this paper are connected to the output of the respective HBCs, and the secondary sides of all the transformers are connected in series for generating the final output voltage. Only one of the transformers, in particular, has a different turn ratio for increasing the output voltage level. In this paper, the possible turn ratio of the special transformer with a different turn ratio is discussed in detail, and a switching method based on the level-shifted switching method for the topology used in this paper is proposed. To verify the effectiveness of the proposed method, a three-phase 21-level CHBI is experimentally tested.

This study introduces and describes a demonstration island of low-voltage direct current (LVDC) distribution system. The LVDC distribution system is planned to be constructed in an island of South Korea named Geochado by a project of KEPCO (Korea Electric Power Corporation). In this study, the network design of the demonstration island is proposed. A new DC network will be installed to demonstrate the LVDC distribution system and is planned to operate with the existing AC network. In addition, this paper presents the composition of loads for the DC network demonstration and distribution energy resources (DER) containing renewable energy resources. A variable speed function is planned to be developed for fuel efficiency operation. To calculate optimal DER capacity, HOMER microgrid economic analysis tool is used. Optimal HOMER results are presented with several cases. The final DER capacity is selected by considering the cost, stability and recent weather conditions. The energy management system is designed for efficient monitoring and control of LVDC distribution system. In addition, heat management system, power management system and automatic demand response are applied for demonstration. Each system interface method and a communication method for systems and field devices are proposed. Finally, the operation strategy for the LVDC distribution system is proposed in this study.

This paper proposes a new type of cascaded ac–ac converter with phase-shift control and reduced number of inductors. It can attain high voltage levels by using standard low-voltage rating semiconductor devices. The proposed converter is resistant to current shoot-through and does not require pulse-width modulation (PWM) dead-time; these lead to greatly enhanced system reliability and effective utilization of PWM voltages. Moreover, it does not require current/voltage polarity sensors, lossy snubbers, or dedicated PWM strategies for commutation. These features make it possible to design the converter with reduced control complexity, and obtain output voltage with less distortion. The cascaded units in the proposed converter share the inductors; therefore, number of inductors, inductors footprints, and magnetic volume can be reduced. The phase-shift PWM control is also presented. It increases the effective frequency of the converter by the number of cascaded units, which decreases the size of the passive components and/or the current and voltage ripples. In order to demonstrate the advantages of the proposed converter, detailed comparative simulations and experimental results of the proposed 2-unit, 3-unit, and 4-unit cascaded converters are provided.

In this paper, a single-phase buck–boost matrix converter is proposed which can both buck and boost the input voltage with step-changed frequency. It consists of only six unidirectional current flowing bidirectional voltage blocking switches, two input and output filter capacitors, and one inductor. It has following advantages over the existing single-phase matrix converters: 1) it can both buck and boost input voltage solving the limited voltage transfer ratio (only boost or buck) problem; 2) it also has enhanced reliability as it is immune from shoot-through problem of voltage source when all switches are turned-on simultaneously, and, therefore, it has no need of PWM dead times and RC snubbers or dedicated soft-commutation strategies to solve the commutation problem; 3) it can also use high-speed power MOSFETs as their body diodes never conduct, which eliminate their poor reverse recovery problem. The operation principle of the proposed converter is given, and switching strategies are developed to obtain various multiples and submultiples of input frequency. To verify its performance, a laboratory prototype is fabricated and experiments are performed to produce step-down and step-up voltage with three different frequencies of 120, 60, and 30 Hz.

Low-voltage direct current (LVDC) distribution has attracted attention due to increased DC loads, the popularization of electric vehicles, energy storage systems (ESS), and renewable energy sources such as photovoltaic (PV). This paper studies a &plusmn, 750 V bipolar DC distribution system and applies a 3-level neutral-point clamped (NPC) AC/DC converter for LVDC distribution. However, the 3-level NPC converter is fundamental in the neutral-point (NP) imbalance problem. This paper discusses the NP balance control method using zero-sequence voltage among various solutions to solve NP imbalance. However, since the zero-sequence voltage for NP balance control is limited, the NP voltage cannot be controlled to be balanced when extreme load differences occur. To maintain microgrid stability with bipolar LVDC distribution, it is necessary to control the NP voltage balance, even in an imbalance of extreme load. In addition, due to the bipolar LVDC distribution, the pole where a short-circuit condition occurs limits the short current until the circuit breaker operates, and a pole without a short-circuit condition must supply a stable voltage. Since the conventional 3-level NPC AC/DC converter alone cannot satisfy both functions, an additional DC/DC converter is proposed, analyzed, and verified. This paper is about a 3-level NPC AC/DC converter system for LVDC distribution. It can be used for the imbalance and short-circuit condition in bipolar LVDC distribution through the prototype of the 300 kW 3-level NPC AC/DC converter system and experimented and verified in various conditions.

This paper describes the design and field application of a high-efficiency single-phase AC/DC converter that is suitable for distribution lines. First, an appropriate AC/DC converter was designed in consideration of the environment of the application system. In order to ensure high efficiency and high reliability, we designed an optimum switching element and capacitor suitable for the converter, and the protection element of the AC/DC converter was designed based on these elements. The control function for the power converter suitable for an LVDC distribution system is proposed for highly reliable operation. The AC/DC converter was manufactured based on the design and its performance was verified during application in an actual low-voltage DC (LVDC) distribution grid through tests at the demonstration site. The application to a DC distribution system in an actual grid is very rare and it is expected that it will contribute to the expansion of LVDC distribution.

This paper introduces and discusses a DC microgrid constructed on an island. KEPCO constructed a DC microgrid system on an island called Seogeochado (West Geocha Island) through the ‘DC Island’ project. With regard to the DC Island project, which operates a DC system from generation source to customer, this paper examines the development of LVDC equipment and the implementation of an LVDC microgrid system based on calculations of the optimal renewable energy capacity performed by HOMER, an economic feasibility analysis tool. Also, this paper suggests a centralized operation method for the DC system that optimizes the operation of a DC microgrid on an island and discusses its demonstration.

As the number of direct current (DC) customers is currently expanding, and distribution lines are changing from alternative current (AC) to DC accordingly, DC distribution lines with a radial structure are also becoming longer. This paper includes an analysis of the characteristics of fault currents in LVDC systems, and proposes a protective coordination method, utilizing AC/DC converters and protection equipment when a fault occurs in direct current lines with radial structure, that has been effectively demonstrated in field verification tests.

As the direct current load and the amount of power generation using renewable energy increases, interest in direct distribution is emerged. Low-voltage direct current (LVDC) distribution converters are classified into two types according to the output voltage unipolar or bipolar. In this paper, a novel bipolar in case of a short circuit to the load and compensation control for unbalanced load is possible. The converter circuit is analyzed according to the switching operation. Then, the transfer function is derived through small signal modeling. The controller is designed by frequency analysis of the transfer function. Finally, experiments were conducted to verify the stability of the proposed topology and the designed controller.

Supplemental figures and related figure legends. (PDF 2496 kb)

This paper presents a simple input-constrained current controller for a DC/DC boost converter with stability analysis that considers the nonlinearity of the converter model. The proposed controller is designed to satisfy the inherent input constraints of the converter under a physically reasonable assumption, which is the first contribution of this paper. The second contribution is providing a rigorous proof of the proposed control law, which keeps the closed-loop system along with the internal dynamics stable. The performance of the proposed controller is demonstrated through an experiment employing a 20-㎾ DC/DC boost converter.

For automotive applications of polymer electrolyte membrane fuel cells, the enhancement of the corrosion resistance of metal bipolar plates has been a critical issue with regard to the lifespan of fuel cell stacks. In this paper, we present a novel method for increasing the lifespan by means of a conductive carbon coating on bipolar plates. Conductive carbon films were plasma coated onto metal bipolar plates in a vacuum at various temperatures. As a result, 316L stainless plates with a 10-nm-thick carbon coating layer on a 20-nm-thick CrN undercoat layer showed-contact resistance of 10.71 mΩcm2@10 kgf/cm2 and a corrosion current of 0.5 μA/cm2@0.6 V. This thin coating layer with high conductivity and excellent corrosion resistance suggests a new, effective coating method for the mass production of metal bipolar plates.

The oro-esophageal tube (OE tube) is widely used in dysphagia patients although its success rate for transition to oral feeding is reported only in stroke patients. The aim of this study was to evaluate the feasibility and outcome of OE tube feeding for patients with dysphagia resulting from various etiologies. The authors reviewed the medical records of 1995 dysphagic patients that had undergone videofluoroscopic swallowing study (VFSS) in a tertiary hospital from April 2002 through December 2009. Of these, 97 patients were recommended to use OE tube feeding based on the VFSS findings. Follow-up VFSS were performed on 54 patients. The mean duration of tube use at the time of follow-up VFSS was 274 days. We evaluated clinical information including age, sex, diet, etiology of dysphagia, location of lesions, duration of intervention, and complications of OE tube feeding. Initially, all 54 patients were fed using the OE tube. After their last follow-up evaluation, 19 patients (35.2 %) resumed full oral feeding without the OE tube, 12 patients (22.2 %) used partial OE tube feeding, and 23 patients (42.6 %) continued OE tube feeding only. Full oral feeding was achieved again most often in brain tumor, stroke, and head and neck cancer patients (54.5, 27.3, and 20.0 %, respectively). Mild adverse events, such as blood-tinged sputum, nausea, dyspepsia, and regurgitation of food, were reported in 4 patients. OE tube feeding is a feasible feeding method also in conditions other than stroke such as brain tumors, and head and neck cancers.

This paper describes a high voltage isolation over 30kV gate driver power supply for solid-state-transformers (SSTs). In order to implement this, several dc-dc converter topologies with a highly isolated high frequency (HF) transformer are examined. The simulation study about the electrostatic field of the HF transformer is performed. Moreover, some galvanic insulation materials are analyzed to enhance the isolation between the primary and the secondary sides of the HF transformer. Finally, the fabricated dc-dc converter and HF transformer are tested and the performance is verified through the experiments.

A well-known problem of three-level neutral point clamped (NPC) inverter is the voltage imbalance in the dc-link capacitors. This paper proposes the dc-link capacitor voltage balancing method where a common offset voltage is injected. The offset voltage consists of a harmonic voltage and a magnitude difference between the upper and the lower capacitors. Theoretical analysis is provided to balance the voltages, and it shows that both the odd and the even harmonics in the injected voltage compensates the unbalanced voltage between the capacitors. The proposed method does not require any hardware modification, so that it is easily implemented. Both the simulations and the experiments are carried out to show the excellent performance of the proposed method.

Increased aortic calcification is associated with mortality after transcatheter aortic valve replacement (TAVR). Because calcification increases vascular stiffness, we hypothesized that this association may be due to increased residual load on the heart after TAVR and that luminal area (which also

As a proportion of generation using renewable energy increases in a power system, the need for facility investment is increasing in not only the distribution system but also the transmission system. However, it is inefficient to invest in new equipment to deal with the short peak output of renewable energy generation. For this reason, this paper proposes a method for operating the grid more flexibly, through an optimal operating strategy of the direct current (DC) line at medium-voltage (MV) level, thereby delaying the facility investment in the transmission line. In order to determine the optimal operating point of the converter connected with a DC line, the swarm intelligence-based optimization technique, which can minimize multi-objective function, is used. In addition, in order to overcome the communication dependency of the centralized control, which needs to receive information about the optimal operating point computed by the system operator, this paper proposes a decentralized emergency control (DEC) method in case of a communication fault.

With the rapid expansion of renewable energy and digital devices, there is a need for direct current (DC) distribution technology that can increase energy efficiency. As a result, DC distribution research is actively underway to cope with the sudden digitization and decentralization of load environment and power supply. To verify the possibility of DC distribution, Korea Electric Power Corporation (KEPCO) Research Institute made a DC distribution system connected with a real power system in Gwangju. The construction of the demonstration area mainly includes design of protection and grounding systems, operating procedures of insulation monitoring device (IMD), and construction of power converters. Furthermore, this paper goes beyond the simulation and the lab testing to apply DC distribution to a real system operation in advance. It is designed as a long-distance low-loaded customer for rural areas and operated by the DC distribution. In addition, safety and reliability are confirmed through field tests of DC distribution elements such as power conversion devices, protection and grounding systems. In particular, to improve the reliability of non-grounding system, the insulation monitoring device was installed and the algorithms of its operational procedures are proposed. Finally, this paper analyzes the problems caused by operating the actual DC distribution and suggests solutions accordingly.

This study focuses on finding ways to derive train's optimal ECO driving pattern, which can improve the ride quality and reduce driving energy consumption with keeping the time interval between the stations. As research method, we compared difference of currently ope-rating train's ATO and MCS driving patterns, and concentrated upon the things need to consider in simulation in order to improve the existing pattern of ATO driving pattern's issues with securing the train operation safety. Determining driving pattern minimizing energy consumption by controlling powering within speed limit and controlling switching to coasting at appropriate point considering the track conditions for each section, and determining braking control starting time considering ride comfort and precise stopping is considered to be most important. Key Words : automatic train operation system(ATO system), ECO driving pattern, electric multiple unit(EMU), manual control supervi-sion(MCS), variable voltage variable frequency Inverter(VVVF Inverter)

This study focuses on finding ECO driving patterns which consider driving safety of the ATO system train and reliability and which optimize efficiency of the driving energy consumption. Research results derived by performing simulation of those 5 models show that the emergency braking which affects safety of passenger and the machinery is minimized, and safe driving speed is maintained by the prohibition of drastic acceleration/deceleration, coasting and constant-speed driving. Therefore if this result is applied to the urban railway train by amending or making ATO program to save energy usage that improve environmental quality, its effects as ECO driving pattern is huge. Key Words : electric multiple unit(EMU), ECO driving pattern, automatic train operation system(ATO system), reliability, emergency braking † Corresponding Author: Keunoh Lee Tel : +82-2-970-6381, E-mail : leeko@seoultech.ac.krDepartment of Safety Engineering, Seoul National University of Science and Technology, 232 Gongrung-ro, Nowon-gu, Seoul 139-743, Korea

In order to increase the reliability and response speed of an Energy Storage System(ESS), the power management algorithm for ESS is proposed using a dual active bridge(DAB) converter. The DAB converter has been popular, because it operates with high performance, high efficiency, galvanic isolation, and an inherent soft-switching feature. The bi-directional power transmission is a characteristic of the dual active bridge converter, permitting flexible interfacing to energy storage devices. This paper suggests a control strategy for the power management among independent components in ESS system. Its test-bed contains the power management algorithm which consists of a bidirectional DC/DC converter, a renewable energy simulator, DC loads, and a DC-bus protector. The proposed power management algorithm is analyzed, which is verified from the proposed ESS test-bed.

This paper proposes a novel dual output boost converter with output voltage balancing capability. The proposed converter can achieve zero voltage switching (ZVS) without additional components or complex techniques. It has low switch current stress when compared to the conventional counterpart converter. A 1kW prototype converter is built and tested to verify the performance of the proposed converter.

We propose a novel convolutional network architecture that abstracts and differentiates the categories based on a given class hierarchy. We exploit grouped and discriminative information provided by the taxonomy, by focusing on the general and specific components that comprise each category, through the min- and difference-pooling operations. Without using any additional parameters or substantial increase in time complexity, our model is able to learn the features that are discriminative for classifying often confused sub-classes belonging to the same superclass, and thus improve the overall classification performance. We validate our method on CIFAR-100, Places-205, and ImageNet Animal datasets, on which our model obtains significant improvements over the base convolutional networks.

Objective To investigate predictive factors for percutaneous endoscopic gastrostomy (PEG) removal, thereby minimizing unnecessary PEG insertion in post-stroke dysphagia. Design Retrospective cohort study. Patients A total of 49 patients who undertook PEG tube insertion for post-stroke dysphagia. Methods Patients were divided into a removal group (n = 8) and a sustaining group (n = 41) depending on the presence of a PEG tube. Patients' demographic data, nutritional status, Charlson's Comorbidity Index (CCI), and video-fluoroscopic swallowing study findings at the time of PEG insertion were compared between the 2 groups. Results Eight out of 49 patients (16.3%) removed the PEG tube at a mean of 4.8 months after the insertion. Demographic data, nutritional status, and CCI were comparable between the 2 groups before tube insertion. Video-fluoroscopic swallowing study findings in the removal group showed a lower prevalence of premature bolus loss (50.0% vs 73.2%; p = 0.032), aspiration (37.5% vs 80.6%; p = 0.012) and pharyngeal trigger delay (12.5% vs 74.2%; p = 0.010) than those in the sustaining group. Conclusion The absence of aspiration or pharyngeal trigger delay in video-fluoroscopic swallowing study findings at the time of PEG insertion may be a predictive factor for eventual removal of PEG tubes. Identification of removal factors will assist in determining PEG insertion.