• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.16-16
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• 1999

• Rubber Technology
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• v.23 no.2
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• pp.121-135
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• 2022

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.4
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• pp.127-134
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• 2012

This study was carried out to suggest an experimental base in selecting the cold tolerance of plants. The cold tolerance of the plants were subject to laboratory low temperature treatments and cold processing time were evaluated using both electrolyte leakage and regrowth test. The Logistic model of nonlinear regression analysis was used to evaluate the lethal temperatures that were predicted with the range of $-16.1{\sim}-24.4^{\circ}C$. The order of low-temperature resistance was Sedum reflexum > S. spurium > Ophiopogon japonicus > S. album > S. takevimense > Dianthus chinensis. At the lowest temperature of $13.4^{\circ}C$ the electrolyte leakage value of the plants were lower than 50% demonstrating that they could be applied stably to the roof installed in Korea during the winter with the lowest temperature of $-13.5^{\circ}C$.

• Journal of The Korean Association For Science Education
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• v.33 no.6
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• pp.1103-1118
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• 2013

In this research, we analysed definitions and examples of conductor and electrolysis concept in middle school science textbooks. We also surveyed 9 senior pre-service teachers' understanding of the concept definitions and appropriate examples. From the analysis of the textbooks, we found that the possibility of misunderstanding of learners is high because of the broad definition concept and narrow list of examples. After confirming the differences among pre-service teachers' understanding of the subject through questionnaires and interviews, they also debated for a need to an agreement on scientific concepts. The pre-service teachers recognized the meaning of social constructivism and the need for an agreement process in teaching science concepts.

• Membrane Journal
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• v.16 no.4
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• pp.276-285
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• 2006

Acid-doped sulfonated poly(aryl ether benzimidazole) (S-PAEBI) copolymers were synthesized by a direct polymerization technique and a doping with phosphoric acid as a dopant, and the polymer electrolyte membranes were fabricated from them by a solution casting method. To optimize the reaction condition, the degree of sulfonation and doping level were varied in the ranges of $0{\sim}60%\;and\;0.7{\sim}5.7$, respectively. Physiochemical properties of the doped membranes were investigated by AFM, TGA and the measurement of proton conductivity. It was found that proton conductivities depend on doping levels of membranes. Conductivity determined at the condition of $130^{\circ}C$ and no humidity was $7.3{\times}10^{-2}S/cm$ for the $H_3PO_4$-doped PAEBI membrane with a doping level of 5.7.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.64-68
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• 2023

The salt concentration process in electrodialysis, which uses electrical energy to enhance ion concentrations in an aqueous electrolyte solution, has been studied on the transfer phenomenon of ions and water molecules over the ion exchange membrane. In this paper, we investigated various parameters for limiting concentration of electrolyte solution and the electroosmosis phenomenon in an electrodialysis system by varying salt concentration of electrolyte solution. The electroosmotic water transport was analyzed by measuring the ions and water fluxes in electrolyte solutions having two different NaCl concentrations (NaCl 2M/4M), and concentration change was observed for various volume ratios of the diluted reservoir to the concentration one As a result, it was found that the higher concentration of the aqueous electrolyte solution, the lower electroosmosis, and the higher volume ratio led to a higher concentration in the dilute reservoir, so the limiting concentration was enhanced and the specific energy consumption decreased.

• Journal of the Korean Electrochemical Society
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• v.19 no.4
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• pp.123-128
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• 2016

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based gel polymer electrolyte incorporating nano-size $Al_2O_3$ ceramic particle was prepared by electrospinning. The gel polymer electrolyte (GPE) incorporated with $Al_2O_3$ ceramic particle showed higher ionic conductivity of $9.5{\times}10^{-2}Scm^{-1}$ than pure PVdF-HFP GPE without ceramic particle and improved the electrochemical stability up to 5.2 V. The GPEs were assembled with $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ (NMC) cathode for electrochemical test. The GPE batteries at 0.1 C-rate delivered $168.2mAh\;g^{-1}$ for pure GPE and $189.6mAh\;g^{-1}$ for hybrid GPE, respectively. Therefore, the incorporation of high dielectric constant ceramic particle will be good strategy to enhance the stability and electrochemical properties of lithium ion gel polymer batteries.

• Membrane Journal
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• v.18 no.4
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• pp.274-281
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• 2008

Covalent-crosslinked sulfonated poly(arylene ether sulfone) (SPAES) copolymers were synthesized copolymerization technique and additionally crosslinked with divinylbenzene (DVB). To optimize the reaction condition, a concentration of crosslinking agent and a reaction time were varied in the ranges of $30{\sim}90\;v/v%$ and $30{\sim}720\;min$. The properties of the crosslinked membranes were investigated by SEM, TGA and the measurement of proton conductivity. It was found that the proton conductivity of crosslinked membranes decreased depending on a degree of crosslinking while water uptake and methanol permeability reduced.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.144.2-144.2
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• 2010

Bipolar plate는 고분자 전해질 연료전지(PEMFC)에서 핵심 부품 중의 하나이고, 전해질 막이나 촉매 등에 비해서는 상대적으로 쉽게 접근할 수 있기 때문에 많은 연구가 수행되고 있다. Bipolar plate를 제조하는 기술은 크게 금속을 프레스 가공하는 방법, graphite 판을 직접 밀링하는 방법 및 고분자/카본계의 press molding 법 등 3가지로 분류되며, 본 연구에서는 3번째 방법에 의해서 bipolar plate를 대량 생산하는 방법에 대해 연구하였다. 고분자 매트릭스는 에폭시계 수지를 사용하였고, 카본계 재료는 graphite 분말과 carbon nanotube를 사용하였다. 이들 재료들을 일정한 비율로 혼합한 후 differential scanning calorimetry(DSC)를 사용하여 열분석 하였고, 그 결과를 Kissinger equation에 대입하여 경화반응 속도론을 연구하였다. 또한, 경화된 에폭시/탄소 복합재료의 전기전도도, 유리전이온도, 표면에너지 특성 등을 분석하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.383-385
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• 2009

비백금계 코발트 전이금속 촉매를 탄소지지체에 담지한 뒤, 암모니아 분위기에서 $500^{\circ}C$에서 3시간 동안 열처리하는 과정을 통해 코발트 질화물 촉매를 제조했다. 제조된 촉매들의 구조와 형태를 각각 XRD, HE-TEM등을 통해 분석하였고, 전위 측정기를 이용한 CV, LSV 결과로부터 촉매의 전기화학적 산소 환원특성을 분석하여, 기존의 연료전지 양극 촉매로 사용되는 고가의 백금촉매를 대체하기 위한 비백금계로서의 가능성을 확인하였다.