• 한국수소및신에너지학회논문집
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• 제18권3호
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• pp.292-300
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• 2007

A dynamic system model of a proton exchange membrane fuel cell(PEMFC) has been developed. The PEMFC of this study has large active area with water cooling in order to simulate the performance of the commercially viable PEMFC system for the transportation. A PEMFC stack model is a transient thermal model which is respond to the dynamic change of the coolant temperature and the flow rate. The dynamic cooling system model has been developed to determine the coolant flow rate and the coolant temperature. Prior to the system level study, thermal management criteria have been set up and brought to the control command of the cooling system. Since the system model is designed to evaluate the effect of thermal management on the system performance, it is attempted to determine the proper control algorithm of the cooling system so that the PEMFC system is working on the thermal management criteria. As a result of simulation, feedback controlled cooling system consumes less power and produce more power comparing with that of conventionally controlled cooling system.

• 한국수소및신에너지학회논문집
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• 제19권4호
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• pp.313-321
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• 2008

Dynamics of the proton exchange membrane fuel cell is specially important when the system is frequently working on transient conditions. Even though the dynamics of proton exchange membrane fuel cell for residential power generation is less critical than that of PEMFC for transportation application, the system dynamics of PEMFC for RPG can be very important for daily start-up and stop. In particular, thermal management of the PEMFC for RPG is very important because the heat generation from electrochemical reaction is delivered to the home for hot water usages. Additionally, the thermal management is also very important for heat balance of the system and temperature control of the fuel cell. The objective of this study is to develop a dynamic system model for the study of PEMFC performance over various BOP options. Basic simulation results will be presented.

• 멤브레인
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• 제7권3호
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• pp.136-141
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• 1997

토양 유기물에서 생물학적 난분해성인 부식물질을 알카리에서 추출하고 산성영역에서 침전되는 성분인 부식산을 정제, 추출하였다. 부식산의 주성분인 카르복실기가 이온교환 능력을 가지고 있는 것을 이용하여 PVA와의 불균질한 이온교환막을 제조하여 생리활성 이온인 $K^+$, $Na^＋$의 이동 및 이동속도를 검토하여 보았다. 그 결과 수소이온 농도가 높을수록 이동속도는 빠르게 나타나고, 특히 $10^-1$,$10^0$영역에서 급격한 변화를 보였다. 또한 $K^+$, $Na^＋$의 농도가 증가함에 따라 그 선택성이 나타났으며, 특히 수소이온농도 $10^0$ 일때는$K^+$이 2배정도 빠르게 이동되고 있다. 따라서 이러한 생리활성 이온의 선택성 및 이동속도의 향상으로 부식산이 이온교환막의 새로운 재료로서의 그 가능성을 나타내었다.

• Korean Chemical Engineering Research
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• 제56권6호
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• pp.909-913
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• 2018

A hydrocarbon trap (HT) plays an important role of controlling vehicle emissions in the so-called cold emission period by holding hydrocarbons until three way catalysts (TWCs) are thermally activated. In this study, we have investigated the adsorption characteristics of cation (H, La, K, and Ag)-exchanged ZSM-5 zeolites for hydrocarbons (propylene, n-butane, and toluene) by DFT (density functional theory)-based computational chemistry. Cation exchange is to improve the hydrothermal stability of zeolites and their adsorption capacity, thereby rendering cation-exchanged zeolites promising materials for HT. The idea of cluster approximation makes the calculation of adsorption energies superbly efficient in computation. The results showed that Ag-exchanged ZSM-5 would be the best for the adsorption of all three adsorbates, without often encountered Ag oxidation in experiments. Besides, the hydrothermal stability of La-exchanged ZSM-5 was confirmed from the change of geometrical parameters by cation exchange, and it showed good adsorption capacity for propylene and toluene. Hydrogen-exchanged ZSM-5 was also good for hydrogen adsorption, but had poor hydrothermal stability.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.524-533
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• 2021

In this study, a series of anion conductive organic/inorganic composite membranes with excellent ionic conductivity and chemical stability were prepared by introducing graphene oxide (GO) inorganic nanofiller into the quaternized poly(phenylen oxide (Q-PPO) polymer matrix. The fabricated organic/inorganic composite membranes showed higher ionic conductivity than the pristine membrane. In particular, Q-PPO/GO 0.7 showed the highest ionic conductivity value of 143.2 mS/cm at 90℃, which was 1.56 times higher than the pristine membrane Q-PPO (91.5 mS/cm). In addition, the organic/inorganic composite membrane showed superior dimensional stability and alkaline stability compared to the pristine membrane, and the physicochemical stability was improved as the content of inorganic fillers increased. Therefore, we suggest that the as-prepared organic/inorganic composite membranes are very promising materials for anion exchange membrane applications with high conductivity and alkaline stability.

• 디지털융복합연구
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• 제19권5호
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• pp.279-284
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• 2021

본 연구에서는 3차원 전산유체역학 (3-D computational fluid dynamics, CFD)을 이용하여 고체고분자전해질형연료전지 (proton exchange membrane fuel cell, PEMFC)의 기체유로에 대한 성능에 관한 전산모사를 실시하였다. 또한 이 전산모사를 통하여 유체의 농도와 압력분포, 그리고 전류밀도의 분포 등 각종 분포에 관하여 연구를 진행하였다. 본 논문에서는 단일유로와 5개의 유로를 비교분석 하였다. 그 결과 5개의 유로가 단일유로에 비하여 각종 분포들이 균일하였고, 성능 또한 월등하였다. 특히 단일유로에서는 물질전달에의한 성능저하 영역에서 매우 낮은 성능을 확인할 수 있었고 반면 5개의 유로에서는 이 부분을 극복하여 보다 높은 성능을 확인할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제20권3호
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• pp.216-223
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• 2009

The relation between temperature and hydrogen desorption on variation in output was investigated for the metal hydride canister. For this study, an AB$_5$ type alloy were chosen as a hydrogen storage material in the metal hydride canister. And application to the single proton exchange membrane fuel cell was evaluated. As the results, the hydrogen desorption was linearly increased as the temperature was risen. In addition, metal hydride canister heating was able to correspond the variation of load as power request in the PEMFC system.

• 한국세라믹학회지
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• 제45권8호
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• pp.472-476
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• 2008

The surface region of commercial stainless steel 304 and 316 plates has been modified through deposition of the multi-layered coatings composed of titanium film ($0.1{\mu}m$) and gold film ($1-2{\mu}m$) by an electron beam evaporation method. XRD patterns of the stainless steel plates deposited with conductive metal films showed the peaks of the external gold film and the stainless steel substrate. Surface microstructural morphologies of the stainless steel bipolar plates modified with multi-layered coatings were observed by AFM and FE-SEM images. The stainless steel plates modified with $0.1{\mu}m$ titanium film and $1{\mu}m$ gold film showed microstructure of grains of under 100 nm diameter. The external surface of the stainless steel plates deposited with $0.1{\mu}m$ titanium film and $2{\mu}m$ gold film represented somewhat grain growth of Au grains in FE-SEM image. The electrical resistance and water contact angle of the stainless steel bipolar plates modified with multi-layered coatings were examined with the thickness of the gold film.

• Korean Chemical Engineering Research
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• 제56권2호
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• pp.151-155
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• 2018

고분자전해질 연료전지(PEMFC)의 고분자막 열화정도는 주로 수소투과전류밀도로 평가한다. 수소투과전류밀도는 선형주사전압전류측정법(Linear Sweep Voltammetry, LSV)으로 측정하는데 DOE프로토콜과 NEDO프로토콜이 분석방법에 차이가 있다. 본 연구에서는 PEMFC 구동 및 가속 열화 시험 과정에서 두 프로토콜을 적용해 수소투과 전류밀도를 비교하였다. DOE 방법에 의한 LSV 방법에서는 주사속도(scan rate) 변화가 수소투과 전류밀도에 영향을 주지만 NEDO 방법에서는 주사속도가 수소투과전류밀도에 영향을 주지 않았다. 고분자막 가습/건조 15,000사이클 평가과정에서 DOE 방법은 막의 열화를 민감하게 측정하였으나 NEDO방법은 DOE방법에 비해 막의 열화가 덜 민감하게 나타났다.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.253-260
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• 2024

Proton exchange membrane water electrolysis (PEMWE) is an efficient method for utilizing renewable energy sources such as wind and solar powers to produce green hydrogen. For PEMWE powered by renewable energy sources, its durability is a crucial factor in its performance since irregular and fluctuating characteristics of renewable energy sources, especially for wind power, can deteriorate the stability of PEMWE. Triangular voltage cycle is well able to simulate fluctuating wind power, but its effect on the durability has not been investigated extensively. In this study, the performance degradation of the PEMWE cell operated with the triangular voltage cycling was investigated at different ramping rates. The measured current responses during the cycling gradually decreased for both ramping rates, and I-V curve measurements before and after the cycling confirmed the degradation of the performances of PEMWE. For both measurements, the degradation rate was larger for 300 mV s^-1 than 30 mV s^-1, and they were determined as 0.36 and 1.26 mV h^-1 (at the current density of 2 A cm^-2) at the ramping rates of 30 and 300 mV s^-1, respectively. The comparison with other studies on triangular voltage cycling also indicate that an increase in the ramping rate accelerates the deterioration of the PEMWE performance. X-ray photoelectron spectroscopy and transmission electron microscopy results showed that the Ir catalyst was oxidized and did not dissolve during the voltage cycling. This study suggests that the ramping rate of the triangular voltage cycling is an important factor for the evaluation of the durability of PEMWE cells.