• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.373-373
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• 2009

Relative humidity, membrane conductivity and water activity are critical parameters of polymer electrolyte membrane fuel cells (PEMFC) for high performance and reliability. These parameters are closely related with temperature. Moreover, the ideal values of these parameters are not always identical along the channels. Therefore, the cooling channel design and its operating condition should be well optimized along the all location of the channels. In the present study, we have performed a numerical investigation on the effects of cooling channels on performance of a PEMFC. Three-dimensional Navier-Stokes equations are solved with the energy equation including heat generated by the electrochemical reactions in the fuel cell. The present numerical model includes the gas diffusion layers (GDL) and serpentine channels for both anode and cathode gas flows, as well as cooling channels. To accurately predict the water transport across the membrane, the distribution of water content in the membrane is calculated by solving a nonlinear differential equation with a nonlinear coefficient, i.e., the water diffusivity which is a function of water content as well as temperature. Main emphasis is placed on the heat transfer between the solid bipolar plate and coolant flow. The present results show that local current density is affected by cooling channels due to the change of the oxygen concentration and the membrane conductivity as well as the water content. It is also found that the relative humidity is influenced by the generated water and the gas temperature and thus it affects the distribution of fuel concentration and the conductivity of the membrane, ultimately fuel cell performance. Unit-cell experiments are also carried out to validate the numerical models. The performance curves between the models and experiments show reasonable results.

• 한국수소및신에너지학회논문집
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• 제7권1호
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• pp.11-18
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• 1996

The Laves phase alloy hydrides have some promising properties as electrode materials in reversible metal hydride batteries. In this work, the hydrogen storage performance, crystallographic parameters, surface morphology, surface area and electrochemical characteristics of the non-stoichiometric $ZrMn_{0.3}V_{0.7}Ni_{1.4+{\alpha}}$, $ZrMn_{0.5}V_{0.5}Ni_{1.4+{\alpha}}$($\alpha$ =0.0, 0.2, 0.4, 0.6) alloys were examined. These as-cast alloys were found to have mainly a cubic C15-type Laves phase structure by X -ray diffraction analysis. The equilibrium pressure of the alloy were increased as $\alpha$ increased in both two types alloy. In case of $ZrMn_{0.5}V_{0.5}Ni_{1.4+{\alpha}}$ alloys, discharge efficiency and the rate capability of the alloy were decreased as $\alpha$ increased but, these values were increased in case of $ZrMn_{0.3}V_{0.7}Ni_{1.4+{\alpha}}$ alloys. The differences of these electrode properties observed were dependent on the reaction surface area and the catalytic activity of unit area of the each electrode.

• Carbon letters
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• 제6권1호
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• pp.41-46
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• 2005

Plasma carbon blacks of 20~30 nm diameter were synthesized by direct decomposition of natural gas using a hybrid plasma torch system with 50 kW direct current and 4 MHz of radio frequency. The insulating rector which inside diameter of 400 mm and length of 1500 mm, respectively was kept at 300~$400^{\circ}C$ during the preparation. The ultimate analysis of plasma carbon blacks reveals that the raw plasma carbon blacks contains a large quantity of volatile which is mainly consist of hydrogen. Therefore devolatilization of raw plasma carbon blacks were carried out at $900^{\circ}C$ for one hour under nitrogen atmosphere. The devolatilization leads to the decrease in electrical resistivity and surface oxygen functional groups of plasma carbon black significantly. In order to investigate the plasma carbon as a catalyst support, devolatilized plasma black at $900^{\circ}C$ (DPB) supported PtAu catalyst was synthesized by sodium boronhydride reduction method. Electrochemical measurements and direct formic acid fuel cell test indicated that catalytic activity of DPB supported PtAu catalyst for formic acid oxidation was similar to that of Vulcan XC-72 of commercial carbon black supported one.

• 공업화학
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• 제3권4호
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• pp.701-709
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• 1992

콜로이드 방법에 의해 은입자를 카본블랙에 담지시켜 알칼리형 연료전지의 산소극의 촉매로 사용하였다. $AgNO_3$와 $NaBH_4$의 혼합용액에 sodium dodecyl benzenesulfonate를 첨가하여 콜로이드 용액을 만들었고 이를 전기영동법으로 확인하였다. 입자크기에 대한 전극성능의 영향과 화학흡착을 고찰한 결과 $200{\AA}$의 촉매로 제조한 전극이 가장 우수하였으므로 이를 위해 계면활성제의 첨가효과, 담지시의 교반시간과 담체로 사용되는 카본의 분산성에 따른 은입자의 응집현상을 검토하였다. 열처리 효과에 의한 입자 크기의 증가를 고려할 때 계면활성제의 첨가량을 $10mg/{\ell}$으로 하고 9시간 교반하여 $100{\AA}$의 입자크기를 갖는 촉매를 제조한 뒤 이를 이용하여 전극을 제작하는 것이 가장 좋았다. 또한 카본블랙을 초음파 분산기로 분산시키는 경우 30초 이후에는 재응집현상이 일어남을 알 수 있었다.

• 방사성폐기물학회지
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• 제9권4호
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• pp.247-258
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• 2011

사용후핵연료의 파이로처리기술에 대한 국내외 특허동향을 분석하였다. 1975-2009년에 걸쳐 한국, 미국, 일본 및 유럽연합에서 출원된 특허에 대하여 출원국별, 출원인별, 연도별 및 세부기술분야별로 구분하여 그 내용을 비교함으로써 파이로처리기술 개발 현황을 분석하였다. 그리고 주요 출원인의 세부기술별 특허활동지수로부터 특정분야의 기술개발 편중도, 분석대상 특허의 피인용횟수와 패밀리수로부터 각국의 기술 경쟁력을 조사하였다. 또 장차 파이로처리기술의 실용화에 대비하여 필수 요소기술들을 도출하고 그에 대한 현기술 수준과 기술개발동향 등을 파악하였다.

• 공업화학
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• 제23권3호
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• pp.297-301
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• 2012

미생물연료전지는 미생물의 신진대사 활동을 통해 자발적으로 바이오매스를 전기로 전환시키는 바이오 전기화학 시스템이다. 본 연구에서는 미생물 접종원으로 활성슬러지를 사용하였으며, 미생물연료전지의 전기생산을 위한 기질로서 유가공 폐수의 적용 가능성을 검토하였다. 전력발생 장치로서 미생물연료전지의 성능을 파악하고자 전지전위, 전력밀도, 순환전압전류 분석 및 지속가능 전력생산에 관한 특성을 유가공 폐수를 적용하여 평가하였다. Chemical Oxygen Demand (COD) 2650 mg/L의 유가공 폐수를 이용한 미생물연료전지 시스템에서 COD가 88% 제거되었으며, 최대 전력밀도는 $40\;mW/m^2$에 도달하였다. 본 연구 결과로부터 유가공 폐수를 효과적으로 처리하는 동시에 전기를 생산하기 위한 미생물연료전지 기술의 적용 가능성을 확인하였다.

• 공업화학
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• 제9권4호
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• pp.523-528
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• 1998

본 연구에서는 고체전해질셀 내에서 작업전극으로 사용된 $V_2O_5$의 전기화학적 특성을 알아보기 위해 YSZ를 고체전해질로 사용하여 전기화학셀(1-Butene+$O_2$, $V_2O_5{\mid}YSZ{\mid}Ag$, $O_2$)을 구성하였다. 상대전극인 Ag는 소성에 따라 sintering이 일어나고 $3{\mu}m$ 이상의 기공을 갖는 구조를 얻었다. 작업전극은 소성조건에 따라 부분산화반응에 영향을 주는 (010)면이 발생되었다. $V_2O_5$의 1-부텐에 대한 주요생성물은 부타디엔이었고 SEP (solid electrolyte potentiometry) 기술을 이용하여 작업전극상에 흡착된 화학종의 화학포텐셜을 측정하였다. 가스조성에 따른 개로전위 (OCV; open circuit voltage)를 측정하여 표면 산소종에 혼합전위의 발생을 확인하였다.

• 공업화학
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• 제31권5호
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• pp.581-584
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• 2020

The effect of a chemical pretreatment on the surface carbon was investigated using a scanning electron microscope (SEM) and electrochemical methods. Primitive carbon has a reducing power likely due to incompletely oxidized functional groups on the surface. We aim to control this reducing power by chemical treatment and apply for the spontaneous deposition of nanoparticles (NPs). Highly ordered pyrolytic graphite (HOPG) was initially treated with a reducing agent, NaBH4 or an oxidizing agent, KMnO₄, for 5 min. Subsequently, the pretreated carbon was immersed in a platinum (Pt) precursor. Unexpectedly, SEM images showed that the reducing agent increased spontaneous PtNPs deposition while the oxidizing agent decreased Pt loading more as compared to that of using bare carbon. However, the amount of Pt on the carbon obviously decreased by NaBH₄ treatment for 50 min. Secondly, spontaneous reduction on pretreated glassy carbon (GC) was investigated using the catalytic hydrogen evolution reaction (HER). GC electrode treated with NaBH4 for a short and long time showed small (onset potential: -640 mV vs. MSE) and large overpotential for the HER, respectively. Although the mechanism is unclear, the electrochemistry results correspond to the optical data. As a proof-of-concept, these results demonstrate that chemical treatments can be used to design the shapes and amounts of deposited catalytic metal on carbon by controlling the surface state.

• Corrosion Science and Technology
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• 제19권2호
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• pp.82-88
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• 2020

This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.51-51
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• 2003

The medicinal plant Cimicifuga Racemosa (Black cohosh) has been used to treat many kinds of neuronal and menopausal symptoms, such as arthritis, menopausal depression, nerve pain, etc. Here, we examined the effect of Cimicifugoside (CF), one of triterpene glycosides which have been known as pharmacologically active ingredients of C. Racemosa, on nicotinic acetylcholine receptor (nAChR)-mediated catecholamine (CA) secretion in bovine adrenal chromaffin cell. Cimicifugoside inhibited calcium increase induced by 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), a nAChR agonist with a half maximal inhibitory concentration (IC50) of 18${\pm}$2${\mu}$M. In contrast, cimicifugoside did not affect the calcium increases evoked by high K$\^$+/, veratridine, and bradykinin. The DMPP-induced sodium increase was also inhibited by cimicifugoside with IC50 of 2${\pm}$0.3${\mu}$M, suggesting that the activity of nAChRs is inhibited by cimicifugoside. Cimicifugoside did not effect on the KCl-induced secretion but markedly inhibited the DMPP-induced catecholamine secretion which was monitored by carbon-fiber amperometry in real time, and by high performance liquid chromatography (HPLC) through electrochemical detection. The results suggest that cimicifugoside selectively inhibits nAChR-mediated response in bovine chromaffin cells.