• Journal of Industrial Technology
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• v.38 no.1
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• pp.15-19
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• 2018

In this study, hyaluronic acid (HA) was electro-spun to fabricate nanofibrous membranes for support materials. Because HA is very hygroscopic, it is difficult to obtain enough viscosity to apply electrospinning method. Therefore, we mixed HA with polyethylene oxide (PEO) to obtain proper viscosity and added adipic acid (ADH) to promote cross-linking of PEO/HA during electrospinning. The morphology of PEO/HA membrane was optimized according to PEO/HA concentration ratio and spinning rate. Finally, we fabricated gold-nanoparticle-embedded PEO/HA membranes and their catalyst activities were evaluated in tetramethylbenzidine (TMB) oxidation.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04b
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• pp.3-10
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• 1997

제염농축공정은 증류, 증발법을 일반적으로 사용하나, 에너지 절약차원에서 전기투석 (Electro dialysis)장치를 증발기 선단에 도입한 복합공정을 국내에서도 사용하고 있는 실정이다. 그러나, 전기투석장치는 전기적인 소모와 막의 재생, 교체처리비가 문제점이 되므로 역삼투 장치를 제염농축 공정 최선단에 도입한 복합공정을 이용할 경우 전기 투석 및 증발 복합공정에 비해 40%의 에너지 절감 효과를 기대할 수 있다. 이와 같은 장점에도 불구하고 역삼투 공정은 공급용액의 삼투압보다 큰 적용압력을 막표면에 가하여 물질분리를 수행하므로 농축공정에서 유발되는 배제액 농도의 상승은 삼투압의 증가를 일으켜 실적적용압력의 효과를 떨어뜨리게 되며 결과적으로 농축효과를 감소시키게 된다. 본 연구에서는 효과적인 염농축 공정을 위하여 막모듈 투과부에 고농도 삼투압 감소액(osmotic sink solution)을 향류식(막투과흐름을 맞받아치며 흐르는 방식)으로 유입시키는 향류식 역삼투 (counter-current reverse osmosis, CCRO) 나권형 모듈을 고안 제작하였으며, 제작된 모듈을 기존 역삼투 공정과 향류식 염삼투 공정에 적용하여 염농축도의 성능을 상호 비교하고 염농축에 관계되는 공급농도, 공급유량, 투과유량, 배제유량, 향류 유입유량, 압력구배, 삼투압차 및 농축단수 등의 인자들을 이용하여 두 공정에 대한 염농축 분리조작의 제반조건과 제작된 모듈 내의 농축관련 특성을 실험 및 수치적으로 비교, 고찰하였다.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.189-195
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• 2016

Micro Hotplate (MHP) is the key component in micro-sensors, particularly gas sensors. Indeed, in metal oxide gas sensors MOX, micro-heater is used as a hotplate in order to control the temperature of the sensing layer which should be in the requisite temperature range over the heater area, so as to detect the resistive changes as a function of varying concentration of different gases. Hence, their design is a very important aspect. In this paper, we have presented the design and simulation results of a meander micro heater based on three different materials - platinum, titanium and tungsten. The dielectric membrane size is 1.4 mm × 1.6 mm with a thickness of 1.4 μm. Above the membrane, a meander heating film was deposed with a thickness of 100 nm. In order to optimize the geometry, a comparative study by simulating two different heater thicknesses, then two inter track widths has also been presented. Power consumption and temperature distribution were determined in the micro heater´s structure over a supply voltage of 5, 6, and 7 V.

• Journal of Hydrogen and New Energy
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• v.32 no.1
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• pp.1-10
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• 2021

Water electrolysis technology, which generates hydrogen using renewable energy resources, has recently attracted great attention. Especially, the polymer electrolyte membrane water electrolysis system has several advantages over other water electrolysis technologies, such as high efficiency, low operating temperature, and optimal operating point. Since research that analyzes performance characteristics using test bench have high cost and long test time, however, model based approach is very important. Therefore, in this study, a system model for water electrolysis dynamics of a polymer electrolyte membrane was developed based on MATLAB/Simulink®. The water electrolysis system developed in this study can take into account the heat and mass transfer characteristics in the cell with the load variation. In particular, the performance of the system according to the stack temperature control can be analyzed and evaluated. As a result, the developed water electrolysis system can analyze water pump dynamics and hydrogen generation according to temperature dynamics by reflecting the dynamics of temperature.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.536-540
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• 2020

The support of the PEMFC membrane plays a key role in improving mechanical durability. The e-PTFE used as a support is chemically stable, so electro-chemical degradation in the PEMFC driving process has been rarely studied. In this study, we investigated whether e-PTFE is chemically stable to radicals and hydrogen peroxide during Fenton reaction. After the Fenton reaction, the main chain of e-PTFE broke, resulting in a change in the chemical structure and morphology of the support, resulting in a decrease in tensile strength. The results of this study showed that electrochemical degradation of the membrane ionomer in the PEMFC process occurs inside the membrane by radicals and hydrogen peroxide, so that electrochemical degradation may also occur at the e-PTFE support in the cell.

• Membrane Journal
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• v.25 no.6
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• pp.488-495
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• 2015

Aminated polyphenylene oxide (APPO) based on polyphenylene oxide (PPO) was synthesized using trimethylamine and chloromethyl ethyl ether. Then, the electro-physical properties of APPO membranes which were prepared from the 8 wt% APPO solution dissolved in chloroform were characterized. Contact angle was $44.4^{\circ}$, swelling degree was 37.9%. The typical electrical properties of ion exchange capacity and ion conductivity were 2.3 meq/g, 0.027 S/cm, respectively. And the single gas permeation experiments were performed by using the time-lag method for $N_2$, $O_2$, $CH_4$, $CO_2$, $SO_2$. For the acid gases of $CO_2$ and $SO_2$, their permeability were measured 20.7 and 511.5 barrers, respectively. In the case of selectivity, $CO_2/CH_4$, $CO_2/N_2$ and $SO_2/CO_2$ were measured 39.8, 42.2, 24.7, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.236-242
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• 2003

Thermal bubbles find their diverse application areas in the MEMS (MicroElectroMechanial Systems) technology, including bubble jet printers, microactuators, micropumps, etc.. Especially, microactuators and micropumps, which use a microbubble growing by a controlled heat input, frequently involve mechanical and thermal interaction of the bubble with a solid structure, such as a cantilever beam and a membrane. Although the concept is experimentally verified that an internal pressure of the bubble can build up high enough to deflect a thin solid plate or a beam, the physics of the entire process have not yet been thoroughly explored. This work reports the experimental study of the growth of a thermal bubble while deflecting a thin cantilever beam. A physical model is presented to predict the elastic response of the cantilever beam based on the experimental measurements. The scaling law constructed through this work can provide a design guide for micro- and nano-systems that employ a thermal bubble for their actuation/pumping mechanism.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.1
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• pp.9-14
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• 2009

The modelling of PEMFC(Proton Exchange Membrane Fuel Cell) has been studied in many kinds of methods. But there are some limitations in application of the developed models to analyze transient phenomena of power systems. The PSCAD/EMTDC is very popular simulation tool in power system areas. To analyze power systems interconnected to PEMFCs, the PSCAD/EMTDC model of the PEMFCs is needed. In this paper, we developed a PSCAD/EMTDC model of PEMFC based on electro-chemical characteristic equations of PEMFC. Also, we performed simulations using the developed model in the PSCAD/EMTDC program and tested appropriateness of the proposed models. The simulations showed good results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.874-877
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• 2001

SOI(Silicon-On-Insulator) technology is proposed as an alternative to bulk silicon for MEMS(Micro Electro Mechanical System) manufacturing. In this paper, we fabricated the SOI wafer with uniform active layer thickness by silicon direct bonding and mechanical polishing processes. Specially-designed electrostatic bonding system is introduced which is available for vacuum packaging and silicon-glass wafer bonding for SOG(Silicon On Glass) wafer. We demonstrated thermopile sensor and RF resonator using the SOI wafer, which has the merits of simple process and uniform membrane fabrication.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.890-896
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• 2004

This study is intended as an investigation of the EK remediation characteristics of natural soil with treatment time under unsaturated conditions. EK tests are performed under the voltage gradient of 1V/cm, the degree of saturation of 82.8%, and the installing of cation exchange membrane. It was found from the results that the acid front is initially transported at 0.75cm/day and then continuously degreased until the transport velocity of the acid front is balanced to the velocity of the base front. The residual lead concentration indicated the maximum value at the treatment time of lOdays, then the increasing of treatment time largely decreases the concentration within the sample though electromigration than electroosmosis.