18 results on '"Han-Jung Kim"'
Search Results
2. Evaporation-Rate Control of Water Droplets on Flexible Transparent Heater for Sensor Application
- Author
-
Dong-Ik Kim, Han-Jung Kim, Suhan Lee, Yoonkap Kim, Young-You Kim, Jaesoung Park, and Sam-Soo Kim
- Subjects
Materials science ,Evaporation rate ,Nanowire ,Evaporation ,wettability ,02 engineering and technology ,lcsh:Chemical technology ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,Defrosting ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Icing ,business.industry ,droplet evaporation ,surface treatment ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Optoelectronics ,Wetting ,0210 nano-technology ,business ,Droplet evaporation ,transparent heater - Abstract
To develop high-performance de- or anti-frosting/icing devices based on transparent heaters, it is necessary to study the evaporation-rate control of droplets on heater surfaces. However, almost no research has been done on the evaporation-rate control of liquid droplets on transparent heaters. In this study, we investigate the evaporation characteristics of water droplets on transparent heater surfaces and determine that they depend upon the surface wettability, by modifying which, the complete evaporation time can be controlled. In addition, we study the defrosting and deicing performances through the surface wettability, by placing the flexible transparent heater on a webcam. The obtained results can be used as fundamental data for the transparent defrosting and deicing systems of closed-circuit television (CCTV) camera lenses, smart windows, vehicle backup cameras, aircraft windows, and sensor applications.
- Published
- 2019
- Full Text
- View/download PDF
3. Hybrid fabrication of LED matrix display on multilayer flexible printed circuit board
- Author
-
Taik-Min Lee, Kyoung Min Kim, Jaehyeong Jeong, Han-Jung Kim, Anton Nailevich Gafurov, Kim In Young, Sung Yong Kim, Hak-Jun Chung, Thanh Huy Phung, and Yoonkap Kim
- Subjects
Matrix (mathematics) ,Fabrication ,Materials science ,business.industry ,Hardware_INTEGRATEDCIRCUITS ,Optoelectronics ,Hardware_PERFORMANCEANDRELIABILITY ,Electrical and Electronic Engineering ,business ,Flexible electronics ,Electronic, Optical and Magnetic Materials - Abstract
This study presents a hybrid fabrication process for LED matrix on flexible multilayer printed circuit boards (PCBs). To prepare for the flexible PCB, a roll-to-roll screen printing process was developed to create a core circuit board by printing on both sides of the flexible substrate. From the core PCB, the lamination and etching processes are then used to form four layers in total. By using the proposed method, we successfully implemented the passive LED matrix display. This approach could be used for other applications that require flexible and multilayer circuits.
- Published
- 2021
4. A cupronickel-based micromesh film for use as a high-performance and low-voltage transparent heater
- Author
-
Jun-Hyuk Choi, Jihye Lee, Dae-Geun Choi, Han-Jung Kim, Jun-Ho Jeong, and Yoonkap Kim
- Subjects
chemistry.chemical_classification ,Materials science ,Fabrication ,Renewable Energy, Sustainability and the Environment ,business.industry ,General Chemistry ,Polymer ,Substrate (electronics) ,Cupronickel ,chemistry ,Transfer printing ,Optoelectronics ,General Materials Science ,Thermal stability ,business ,Low voltage ,Voltage - Abstract
The fabrication of uniformly interconnected cupronickel (CuNi) micromesh films on glass and polymer substrates with seamless junctions has been achieved using a simple transfer printing method. When used as a transparent heater, these CuNi micromesh films exhibited an effective and rapid heating performance at low input voltages (below DC 9 V) that can be attributed to the creation of a high quality network over the whole surface area that offers a relatively high transmittance, strong adhesion to its substrate and good mechanical flexibility. A high thermal stability and reliability was also observed relative to a pure Cu micromesh film. Transparent heaters based on CuNi micromesh are therefore considered suitable for providing anti-fogging or de-icing in optics and optoelectronic devices, as well as for wearable heating systems.
- Published
- 2015
5. Hysteresis and reversible red-shift in the reflectance spectra of single-layer porous silicon during exposure to various organic vapors
- Author
-
Han-Jung Kim, Young-You Kim, Dae-Geun Choi, and Jeong-Hwa Lee
- Subjects
inorganic chemicals ,Materials science ,Silicon ,Capillary condensation ,business.industry ,Scanning electron microscope ,technology, industry, and agriculture ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,equipment and supplies ,Porous silicon ,complex mixtures ,Semimetal ,chemistry.chemical_compound ,Optics ,chemistry ,Acetone ,Wafer ,Methanol ,business - Abstract
We fabricated single-layer porous silicon (PSi) on a p +-type silicon wafer and investigated its reflectance spectrum on exposure to different concentrations of various organic vapors. When the PSi sample was exposed to methanol, acetone, ethanol, and isopropanol vapors, the reflectance spectrum promptly shifted toward longer wavelengths by about 1.5, 4.5, 7.0, and 9.0 nm, respectively. The PSi sample showed excellent sensing ability under different concentrations and types of organic vapors. In addition, a slight hysteresis of the red-shift was observed during repeated exposure to an organic vapor at different concentrations. After the organic vapors had been removed, the reflectance spectrum promptly returned to its original state.
- Published
- 2014
6. Guideline Construction through Case Study for Applying Crowdsourcing into New Product Development Environment
- Author
-
Joon Young Park and Han Jung Kim
- Subjects
Engineering ,Knowledge management ,Crowdsourcing software development ,business.industry ,New product development ,Community management ,Guideline ,Business model ,business ,Product type ,Crowdsourcing ,Open innovation - Abstract
In this study, we propose the guideline with strategic model for new product development. To establish the guideline, 1) we classify several types of successful surveyed cases that achieved open innovation through applying crowdsourcing into new product development environment, 2) draw case maps using two or three axis with characteristics such as: step of product development process, crowdsourcing frequency, and product type of each case, 3) define the type of applying crowdsourcing into new product development environment based on case analysis results, and tabulate a crowdsourcing type based on the defined crowdsourcing type, 4) finally, suggest the guideline with multiple points of view which embrace type of crowd, community management, participation method, knowledge adoption method, and reward policy. Using the suggested guideline will help a company to design and establish open innovation in new business model related to product development area.
- Published
- 2013
7. Polymer-free Vertical Transfer of Silicon Nanowires and their Application to Energy Storage
- Author
-
Dae-Geun Choi, Jihye Lee, Jong Hyeok Park, Sang Eon Lee, Wanjung Kim, Hwan Jin Kim, and Han Jung Kim
- Subjects
Silicon ,Materials science ,Nanowires ,business.industry ,General Chemical Engineering ,Electric Conductivity ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,Substrate (electronics) ,Lithium ,Isotropic etching ,Anode ,Electric Power Supplies ,General Energy ,chemistry ,Electrode ,Environmental Chemistry ,Optoelectronics ,General Materials Science ,business ,Electrodes ,Layer (electronics) ,Power density - Abstract
Silicon nanowires (SiNWs) for use as lithium-ion battery (LIB) anode materials have been studied for their one-dimensional (1D) properties and ability to accommodate large volume changes and avoid rapid capacity fading during cycling. Although the vertical transfer of SiNWs from their original substrate onto a conducting electrode is very important, to date, there has been no report of a direct integration method without polymer binders. Here, we propose for the first time a vertical transfer method for SiNWs grown on a Si substrate directly to the current-collecting electrode without using a polymer adhesive for the use as a binder-free LIB anode. The vertical SiNWs produced using a low-cost wafer-scale metal-assisted chemical etching (MaCE) process have been successfully transferred directly to a copper electrode coated with a thin Ag layer by using a simple hot pressing method. When evaluated as an LIB anode without using conventional polymeric binder and a conducting additive, the transferred vertically aligned SiNWs showed a high specific capacity (≈2150 mAh g(-1) ) and excellent rate performance. It is believed that the anode-manufacturing process is simple and fast, thus enabling a large-scale production that is of low-cost, broadly applicable, and provides new avenues for the rational engineering of Si-based electrode materials with enhanced power density and conductivity.
- Published
- 2013
8. Porous silicon layer for optical sensing of organic vapor
- Author
-
Han-Jung Kim, Ki-Won Lee, Young-You Kim, Horchhong Cheng, and Ha Dong Han
- Subjects
inorganic chemicals ,Materials science ,Silicon ,Capillary condensation ,business.industry ,technology, industry, and agriculture ,Analytical chemistry ,chemistry.chemical_element ,equipment and supplies ,Condensed Matter Physics ,Distributed Bragg reflector ,Porous silicon ,complex mixtures ,Optical microcavity ,Electronic, Optical and Magnetic Materials ,law.invention ,Optics ,chemistry ,law ,Electrical and Electronic Engineering ,business ,Porous medium ,Layer (electronics) ,Refractive index - Abstract
The objective of this study is to evaluate the feasibility of porous silicon (PS) layer as a vapor sensor. We prepared three types of PS layer samples – a single layer, distributed Bragg reflector (DBR) layer, and microcavity layer – and examined their reflectance spectra before, during, and after exposure to different concentrations of various organic vapors. When the PS layer samples were exposed to the organic vapors, their reflectance spectra promptly shifted toward longer wavelengths. We determined that this redshift in the reflectance spectra could be attributed to the changes in the refractive index induced by the capillary condensation of organic vapors in the pores of the PS layers. The PS layers showed excellent sensing ability under different concentrations and types of organic vapors. Once the organic vapors were removed, the reflectance spectra of the PS layer samples promptly returned to their original states. In this study, we successfully demonstrated the rapid, sensitive, and reversible sensing of organic vapors using different PS layers.
- Published
- 2011
9. Life Cycle Cost Method by Segregation of Safety and Function
- Author
-
Joon-Gu Lee, Jeong-Jae Lee, Nam-Su Jung, Won Choi, Hyung-Jin Lee, Jong-Ok Kim, Seong-Su Yoon, and Han-Jung Kim
- Subjects
Engineering ,Serviceability (structure) ,Survival probability ,business.industry ,Maintenance strategy ,Analytic hierarchy process ,business ,Subdivision ,Reliability engineering - Abstract
An advanced model for assessing life cycle cost of the facility containing several subdivisions has been proposed with systems engineering approach. This model evaluates the maintenance cost in the sphere of the safety as well as in that of its functionality. The proposed approach has been shown to be more reasonable and practical than existing models. The serviceability and reasonability have been proved through evaluating life cycle cost of the reservoir which is a representative agricultural facility. In addition, the proposed method is helpful to make a maintenance strategy using the survival probability in the point of safety and functionality.
- Published
- 2008
10. Survey for the Management of Reservoirs under Control of Local Authorities of Reservoir of City.Gun in Korea
- Author
-
Jong-Ok Kim, Jeong-Jae Lee, Han-Jung Kim, Seong-Su Yoon, Yicheol Han, Nam-Su Jung, Won Choi, and Hyung-Jin Lee
- Subjects
Flood control ,Geography ,business.industry ,Agriculture ,Amenity ,Management system ,Environmental resource management ,Control (management) ,Reservoir management ,Future value ,business ,Corporation - Abstract
There are many agricultural facilities (46.7%) that have been over 30 years in the Republic of Korea (the ratio of reservoirs built before 1945 is 53%, from 1946 to 1971 is 35%). In the case of reservoirs which do most important functions among these facilities, only 3,000 reservoirs are managed by Korea Rural Community & Agriculture Corporation (KRC) and the other 15,000 reservoirs are managed by local authorities (City and Gun). But, 15,000 reservoirs included in City. Gun have been built in more wide area than KRC and the reservoir management system has not been operated well because of shortage of budget and manpower of the local authorities. Particularly, the abnormal weather happened during every summer season recently has ruined a lot of rural community facilities. So flood control function have been more important than irrigation function in agricultural reservoir system and it may be required to introduce new safe, management and maintenance techniques in City Gun reservoirs. So we investigated landscapes and deteriorations of agricultural reservoirs managed by local small governments for revealing not only present usage but also future value. Survey shows that there are no structural managements except typical hydrological reportings and the deterioration of small darn is very serious. There are needs for more systematic management system and equipment methods. Therefore, this study may suggest that reservoir (that takes charge of the greatest deal of weight in all agricultural facilities) must be considered as new concept of the usage and the unification. On the other hand, reservoir must be also developed as amenity resources, natural circumstances and district values.
- Published
- 2008
11. Transmission-Type Radio-Frequency Single-Electron Transistor with In-Plane-Gate Single-Electron Transistor
- Author
-
S. H. Son, Yong Gyu Kim, Yun Seop Yu, Sungwoo Hwang, Hee Tae Kim, Doyeol Ahn, Bum Ho Choi, Jung Hyun Oh, and Han-Jung Kim
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Transistor ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,Coulomb blockade ,Electrometer ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Signal ,law.invention ,Transmission (telecommunications) ,law ,Optoelectronics ,Wafer ,Radio frequency ,business ,Voltage - Abstract
We have fabricated an in-plane-gate (IPG) single-electron transistor (SET) on an AlGaAs/GaAs wafer and characterized it by measuring a transmitted signal from the transmission-type radio-frequency SET (RF-SET) electrometer system consisting of a resonant tank (LC) circuit and a SET. By measuring the frequency characteristics, we estimate the resonance frequency of the system to be 480 MHz at temperature T=4.2 K. We find that, driving the SET at this frequency, the transmitted signal depends on the gate voltage, and successfully demonstrates the measuring operation. However, the difference between the transmitted signals at the on- and off-gate voltages of the SET was measured to be 0.15 dB, which is relatively small, and it is necessary to optimize the electrical environment of the system by improving the signal-to-noise ratio.
- Published
- 2007
12. 13.2% efficiency Si nanowire/PEDOT:PSS hybrid solar cell using a transfer-imprinted Au mesh electrode
- Author
-
Jun-Hyuk Choi, Min-Joon Park, Dae-Geun Choi, Kwang-Tae Park, Jung-Ho Lee, Jihye Lee, Han-Jung Kim, and Jun-Ho Jeong
- Subjects
Multidisciplinary ,Materials science ,Fabrication ,business.industry ,Energy conversion efficiency ,Nanowire ,Hybrid solar cell ,Article ,Polymer solar cell ,Indium tin oxide ,PEDOT:PSS ,Electrode ,Optoelectronics ,business - Abstract
In recent years, inorganic/organic hybrid solar cell concept has received growing attention for alternative energy solution because of the potential for facile and low-cost fabrication and high efficiency. Here, we report highly efficient hybrid solar cells based on silicon nanowires (SiNWs) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) using transfer-imprinted metal mesh front electrodes. Such a structure increases the optical absorption and shortens the carrier transport distance, thus, it greatly increases the charge carrier collection efficiency. Compared with hybrid cells formed using indium tin oxide (ITO) electrodes, we find an increase in power conversion efficiency from 5.95% to 13.2%, which is attributed to improvements in both the electrical and optical properties of the Au mesh electrode. Our fabrication strategy for metal mesh electrode is suitable for the large-scale fabrication of flexible transparent electrodes, paving the way towards low-cost, high-efficiency, flexible solar cells.
- Published
- 2015
13. Rapid Low-Temperature 3D Integration of Silicon Nanowires on Flexible Substrates
- Author
-
Jihye Lee, Eung-Sug Lee, Yoonkap Kim, Han-Jung Kim, Jun-Hyuk Choi, Jae-Hyun Kim, Sohee Jeon, Jun-Ho Jeong, Dae-Geun Choi, and Joo-Yun Jung
- Subjects
chemistry.chemical_classification ,Nanostructure ,Materials science ,Graphene ,business.industry ,Nanotechnology ,General Chemistry ,Polymer ,Flexible electronics ,law.invention ,Biomaterials ,chemistry ,law ,Photovoltaics ,General Materials Science ,Ultrasonic sensor ,business ,Layer (electronics) ,Ohmic contact ,Biotechnology - Abstract
The vertical integration of 1D nanostructures onto the 2D substrates has the potential to offer significant performance gains to flexible electronic devices due to high integration density, large surface area, and improved light absorption and trapping. A simple, rapid, and low temperature transfer bonding method has been developed for this purpose. Ultrasonic vibration is used to achieve a low temperature bonding within a few seconds, resulting in a polymer-matrix-free, electrically conducting vertical assembly of silicon nanowires (SiNWs) with a graphene/PET substrate. The microscopic structure, and mechanical and electrical characteristics of the interface between the transferred SiNW array and graphene layer are subsequently investigated, revealing that this creates a mechanically robust and electrically Ohmic contact. This newly developed ultrasonic transfer bonding technique is also found to be readily adaptable for diverse substrates of both metal and polymer. It is therefore considered as a valuable technique for integrating 1D vertical nanostructures onto the 2D flexible substrates for flexible photovoltaics, energy storage, and water splitting systems.
- Published
- 2015
14. Observation of convection phenomenon by high-performance transparent heater based on Pt-decorated Ni micromesh
- Author
-
Dong-Ik Kim, Gyuseok Choi, Yoonkap Kim, Dong Wook Lee, Young-You Kim, Sam-Soo Kim, Han-Jung Kim, and Sung-Eun Park
- Subjects
Convection ,Materials science ,business.industry ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,Sputter deposition ,Particulates ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Durability ,lcsh:QC1-999 ,0104 chemical sciences ,chemistry ,Transfer printing ,Sputtering ,Electrode ,Optoelectronics ,0210 nano-technology ,business ,Platinum ,lcsh:Physics - Abstract
In this study, we report for the first time on the convection phenomenon for the consistent and sensitive detection of target materials (particulate matter (PM) or gases) with a high-performance transparent heater. The high-performance transparent heater, based on Pt-decorated Ni micromesh, was fabricated by a combination of transfer printing process and Pt sputtering. The resulting transparent heater exhibited excellent mechanical durability, adhesion with substrates, flexibility, and heat-generating performance. We monitored the changes in the PM concentration and temperature in an airtight chamber while operating the heater. The temperature in the chamber was increased slightly, and the PM2.5 concentration was increased by approximately 50 times relative to the initial state which PM is deposed in the chamber. We anticipate that our experimental findings will aid in the development and application of heaters for sensors and actuators as well as transparent electrodes and heating devices. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.
- Published
- 2017
15. Multiparametric sensor based on DBR porous silicon for detection of ethanol gas
- Author
-
Young-You Kim, Han-Jung Kim, and Ki-Won Lee
- Subjects
Materials science ,Photoluminescence ,Fabrication ,business.industry ,Hybrid silicon laser ,Analytical chemistry ,General Physics and Astronomy ,Porous silicon ,Distributed Bragg reflector ,Wavelength ,Electrical resistance and conductance ,Optoelectronics ,General Materials Science ,Wafer ,business - Abstract
We are here concerned with fabrication possibility of multiparametric gas sensor based on porous silicon. In order to use the porous silicon as a gas sensor, we made the DBR (distributed Bragg reflector) porous silicon onto silicon wafer and monitored the change of three parameters during exposure of DBR porous silicon to ethanol gas. The sensing parameters were the shift of reflectance peak, the PL (photoluminescence) intensity, and the electrical conductance. As a result, the spectra of reflectance and PL shifted toward longer wavelength. The electrical conductivity increases rapidly. After removing the gas, all sensing parameters return exactly to the initial value.
- Published
- 2010
16. Clinical Approach to the Standardization of Oriental Medical Diagnostic Pattern Identification in Stroke Patients
- Author
-
Han Jung Kim, Jung-Mi Park, Hyung Sup Bae, Sang Kwan Moon, Woo Sang Jung, and Seong-Uk Park
- Subjects
Pediatrics ,medicine.medical_specialty ,Medical diagnostic ,Stroke patient ,Article Subject ,business.industry ,Phlegm ,MEDLINE ,Regression analysis ,lcsh:Other systems of medicine ,Blood stasis ,lcsh:RZ201-999 ,Pattern identification ,Complementary and alternative medicine ,Sample size determination ,Medicine ,medicine.symptom ,business ,Research Article - Abstract
In Korea, many stroke patients receive oriental medical care, in which pattern-identification plays a major role. Pattern-identification is Oriental Medicine's unique diagnostic system. This study attempted to standardize oriental medical pattern-identification for stroke patients. This was a community-based multicenter study that enrolled stroke patients within 30 days after their ictus. We assessed the patients' general characteristics and symptoms related to pattern-identification. Each patient's pattern was determined when two doctors had the same opinion. To determine which variables affect the pattern-identification, binary logistic regression analysis was used with the backward method. A total of 806 stroke patients were enrolled. Among 480 patients who were identified as having a certain pattern, 100 patients exhibited the Fire Heat Pattern, 210 patients the Phlegm Dampness Pattern, nine patients the Blood Stasis Pattern, 110 patients the Qi Deficiency Pattern, and 51 patients the Yin Deficiency Pattern. After the regression analysis, the predictive logistic equations for the Fire Heat, Phlegm Dampness, Qi Deficiency, and Yin Deficiency patterns were determined. The Blood Stasis Pattern was omitted because the sample size was too small. Predictive logistic equations were suggested for four of the patterns. These criteria would be useful in determining each stroke patient's pattern in clinics. However, further studies with large samples are necessary to validate and confirm these criteria.
- Published
- 2011
- Full Text
- View/download PDF
17. A compact analytical current conduction model for a depletion-mode n-type nanowire field-effect transistor with a bottom-gate structure
- Author
-
Jung Hyun Oh, Doyeol Ahn, Han Jung Kim, Sungwoo Hwang, Se Han Lee, and Yun Seop Yu
- Subjects
Materials science ,Equivalent series resistance ,business.industry ,Transistor ,Mode (statistics) ,Nanowire ,Structure (category theory) ,Condensed Matter Physics ,Electronic circuit simulation ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,Materials Chemistry ,Optoelectronics ,Field-effect transistor ,Electrical and Electronic Engineering ,Current (fluid) ,business - Abstract
A compact analytical current conduction model for depletion-mode n-type nanowire field-effect transistors (NWFETs) with a bottom-gate structure is introduced. Our model includes the current conductions of bulk charges through the center neutral region as well as of accumulation charges through the surface accumulation region, and thus it includes all current conduction mechanisms of the NWFET operating under various bias conditions. Our model also includes surface depletion effects and series resistance effects. The NWFET model is implemented to the circuit simulator ADS, and the intrinsic part of the NWFET is developed by utilizing the symbolically defined device which is an equation-based nonlinear model. The results simulated from the newly developed NWFET model reproduce two types of the reported experimental results within a 10% error.
- Published
- 2008
18. Modeling of Semiconductor Nanowire Field-Effect Transistors Considering Schottky-Barrier-Height Lowering
- Author
-
Yun Seop Yu, Se Han Lee, Sungwoo Hwang, Doyeol Ahn, and Han Jung Kim
- Subjects
Semiconductor ,Materials science ,business.industry ,Schottky barrier ,Nanowire ,General Physics and Astronomy ,Optoelectronics ,Field-effect transistor ,Thermionic emission ,business ,Thermionic field emission - Published
- 2007
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.