• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1086_1087
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• 2009

본 논문에서는 과도 응답 특성에 따른 고분자 전해질 연료전지(PEMFC)를 모델링하였다. 연료전지에 이러한 과도특성이 일어나는 것에 원인에 대하여 분석해보고, 실제 실험을 통해 과도특성이 일어나는 것을 확인하였다. 실험결과 파형을 분석하여 Matlab & Simulink를 이용하여 PEMFC의 과도 응답 특성을 모델링하였다.

• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.580-589
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• 2014

The concepts used to explain specific phenomenon can be influenced by context or coherent regardless of context. The purpose of this study is to understand middle school students' concept of particles in particular context and to investigate the effects of context on concept of particles. A conceptual questionnaire was developed to find out how students represented particles in two contexts: solid and solution states of electrolytes, and ion precipitation reaction. The questionnaire was administered to $9^{th}$ grade students after classes of 'electrolyte and ions' unit. The responses of students were analyzed using framework developed for categorization of students' concepts. The results are as follows: First, it was found that students used various concepts on particles when they explained solid and solution state of electrolytes, respectively. Second, we identified students' concepts of particles used to explain ion precipitation reaction. In addition, we recognized that majority of students failed to write correct chemical symbols. Third, approximately 79% of students showed coherent responses for explanation of particles in solution state of both electrolytes and ion precipitation reaction. About 57% of students had scientific concepts. Some suggestions were made based on results for acquisition of scientific concepts on particles in different contexts.

• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.183-195
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• 2014

In order to study the mineralogical characteristics of a cathodic deposition-metallic powder, electrowinning experiments were carrier out on different electrolytic solutions at varying electric distances and electric currents. Under the same experimental conditions, Cu recovery was obtained much more effectively using a sodium chloride electrolyte than with a sulfuric acid electrolyte. In XRD analysis, copper ($Cu^0$), chalcanthite and cuprite were identified in the sulfuric acid electrolyte, while copper, nantokite and chalcanthite were observed in the sodium chloride electrolyte. In the sodium chloride electrolyte solution, increasing the electric distance and the electric current increased the Cu recovery rate, anode weight and anodic corrosion. The results of XRD analysis with non-pulverized cathodic deposition-metallic powder showed the average copper crystallite size was increased by increasing the electric current and decreasing the electric distance. It is suggested that the mass transfer was controlled with diffusion on the boundary between the electrode and the electrolytic solution due to the formation of dendrite copper.

• Composites Research
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• v.29 no.6
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• pp.395-400
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• 2016

Recently, many research groups have studied on the epoxy-based multifunctional electrolyte to develop the structural composite bearing high mechanical properties without sacrificing the ionic conductivity at the same time. The studies on the optimal content and material selection for structural electrolyte have been published, while its curing behavior has not much analyzed yet. In this study, epoxy-based structural electrolyte containing solid electrolyte was prepared by varying the curing temperature and time. In addition, the ionic conductivities and mechanical properties of specimens were measured. We also find out the optimal hardening condition where the epoxy domain enables to be hardened within the range of temperature at which the thermal decomposition of electrolyte does not occur. Finally, we propose the multifunctional structural electrolyte showing achievable electrical and mechanical properties (282 MPa and $9{\times}10^{-6}S/cm@25^{\circ}C$).

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.57-63
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• 2015

The hydrogen was charged TRIP steel by electrochemical method under 0.5M $H_2SO_4$ electrolyte and 0.5M NaOH electrolyte with hydrogen charging conditions respectively. The degree of hydrogen embrittlement of TRIP steel was evaluated by using micro Vickers hardness tests. These results showed that the degree of hydrogen embrittlement in acidic electrolyte with hydrogen penetration and hydrogen diffusion through the depth of specimen was more sensitive than its alkaine electrolyte between two type electrolytes. However, it was investigated that micro Vickers hardnesses of surface in acidic electrolyte under two electrolyte were higher than those of alkaine electrolyte. It was thought that in case of hydrogen embrittlement in acid-ice electrolyte, hydrogen charging time was more effective than current density, in case of alkaine electrolyte, hydrogen current density was more effective than charaging time.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.51-58
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• 2008

Many researches for effects of different flow configurations on performance of Proton Exchange Membrane Fuel Cell have extensively been done but the effects of flow direction at the same flow channel shape should be considered for optimal operation of fuel cell as well. In this paper a numerical computational methode for simulating entire reactive flow fields including anode and cathode flow has been developed and the effects of different flow direction at parallel flow was studied. Pressure drop along the flow channel and density distribution of reactant and products and water transport, ion conductivity across the membrane and I-V performance are compared in terms of flow directions(co-flow or counter-flow) using above numerical simulation method. The results show that the performance under counter-flow condition is superior to that under co-flow condition due to higher reactant and water transport resulting to higher ion conductivity of membrane.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.69.1-69.1
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• 2018

산업 현장에서 자주 사용되는 알루미늄 합금은 순도가 높은 알루미늄에 비해 경제성, 기계적 성질이 우수한 장점이 있다. 하지만 이런 합금들은 물리적, 화학적 성질이 순수 알루미늄과 달라 양극산화와 같은 표면처리가 쉽지 않다. 양극산화는 표면처리 기술의 대표적인 방법 중 하나로 인위적으로 산화피막을 형성하는 기술이다. 순도가 높은 알루미늄은 산성 전해질에서의 양극산화를 통해 다공성 산화피막을 형성할 수 있으며 그 구조로 인해 내식성, 내마모성 등 기계적, 화학적인 다양한 장점이 있다. 하지만, Mg, Si, Cr과 같은 성분이 함유된 알루미늄의 경우 산성 전해질에서 산화물을 형성되지 않는다. 본 연구에서 기존의 산성 전해질에서의 양극산화 방법이 아닌$K_2HPO_4$를 함유하는 고온의 글리세롤 전해질을 사용하여 양극산화를 진행하였다. 사용한 알루미늄은 산업용으로 자주 사용되는 3000계열의 알루미늄을 사용하였으며 균일한 양극산화를 위해 샌드페이퍼를 통한 연마과정을 통해 표면을 평탄화 하였다. 이후 전기화학적 에칭 과정을 거쳐 표면에 있는 자연산화막을 제거하여 표면 분석을 용이하게 하였다. 양극산화는 10wt%의 $K_2HPO_4$/글리세롤 전해질에서 전해질의 온도와 인가 전압을 달리 하여 진행하였다. 결과 $150^{\circ}C$ 이상의 온도에서 알루미늄 합금의 양극산화를 확인할 수 있었고 $170^{\circ}C$의 온도에서 인가 전압을 20V로 하였을 때 가장 정렬된 다공성 구조를 얻을 수 있었다. 본 연구 결과를 통해 산업용 알루미늄 합금의 양극산화를 통해 다공성 나노구조 산화물을 형성 시킬 수 있었다.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1591-1596
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• 2020

The solid-state electrolyte based on polymer has great attention to develop its ionic conductivity from conventional polymer electrolyte by using wide range of ionic liquids with remarkable processability, flexibility and is applicable to various electrochemical devices including batteries, supercapacitor. Polymer electrolyte based on Ionic liquid with high conductivity, wide electrochemical stability, thermal stability is used in various electronic devices. In this work, we have investigated and developed solid-state electrolyte based on ionic liquid and polymer with enhanced ionic conductivity and electrochemical performances to conduct to various electronic devices including secondary battery. The ionic conductivity of polymer based solid state electrolyte with optimized ratio of the ionic liquid was 1.46-2 S/cm. The ionic liquid and polymer based electrolyte with enhanced ionic conductivity is promising candidates to utilize in wide range of secondary batteries.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1253-1258
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• 2019

The solid-state electrolyte based on polymer is applicable to various electrochemical devices including supercapacitor, battery, sensor, actuator and has great attention to develop its ionic conductivity from conventional polymer electrolyte by uisng wide range of ionic liquids. The research about ion gel as a solid state electrolyte with the ionic liquid has focused on the wearable and flexible electronic device to use as the high electrical and electrochemical performances, mechanical strength of polymer. In this work, we have investigated and developed solid-state electrolyte based on the ionic liquid and polymer with enhanced ionic conductivity and stability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4013-4018
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• 2014

A 0.45 $cm^2$ DSSC device with a glass/FTO/blocking layer/$TiO_2$/N719(dye)/electrolyte/50 nm-Pt/50 nm-Au/FTO/glass was prepared to examine the stability of the Au/Pt bilayered counter electrode (CE) with electrolyte and the energy conversion efficiency (ECE) of dye-sensitized solar cells (DSSCs). For comparison, a 100 nm-thick Pt only CE DSSC was also prepared using the same method. The photovoltaic properties, such as the short circuit current density ($J_{sc}$), open circuit voltage ($V_{oc}$), fill factor (FF), and ECE, were checked using a solar simulator and potentiostat with time after assembling the DSSC. The microstructure of the Au/Pt bilayer was examined by optical microscopy after 0~25 minutes. The ECE of the Pt only CE-employed DSSC was 4.60 %, which did not show time dependence. On the other hand, for the Au/Pt CE DSSC, the ECEs after 0, 5 and 15 minutes were 5.28 %, 3.64 % and 2.09 %, respectively. The corrosion areas of the Au/Pt CE determined by optical microscopy after 0, 5, and 25 minutes were 0, 21.92 and 34.06 %. These results confirmed that the ECE and catalytic activity of Au/Pt CE decreased drastically with time. Therefore, a Au/Pt CE-employed DSSC may be superior to the Pt only CE-employed one immediately after integration of the device, but it would degrade drastically with time.