• 전기화학회지
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• 제11권4호
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• pp.289-296
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• 2008

산업용 밀폐형 니켈수소전지에 사용되는 수산화니켈 및 수소저장합금 전극에 대해 반쪽전지 시험에 의한 전기화학적 특성을 조사하고, 대용량 밀폐형 니켈수소전지를 제작하여 전지의 충전 효율 및 내압 특성에 대해 평가하였다. 전기화학적 특성 실험은 전지의 충방전 사이클에 따른 전지 내압 상승 억제를 목표로 수산화니켈 전극 및 수소저장합금 전극에 대해 전위주사법을 이용하여 수행하였다. 전위주사법 실험 결과, 수산화니켈 전극의 프로톤 산화 환원 반응 양태, 산소발생 거동, 그리고 수소저장합금 전극의 수소화 반응 특성을 명확히 파악할 수 있었다. 또한 산소 과전압이 높은 수산화니켈 분말과 수소 활성화 특성이 우수한 수소저장합금 분말을 사용하여 제작한 130 Ah 니켈수소전지의 충전 효율은 1 C 전류로 충전 시 98% 수준이 얻어 졌으며 과충전 시 전지 내압이 4 atm 이하로 유지됨을 확인하였다. 그리고 충방전 사이클에 의한 전지 보존 용량도 약 400 사이클에서 약 95% 수준으로 그 특성이 우수함을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.440-447
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• 2006

Solid polymer electrolyte(SPE) membrane with electrodes embedded on both faces offer unique possibilities for the electrochemical cells like water electrolyzer with fuel cell. The Nafion 117 membrane was used as the SPE, and $Pt(NH_3)_4Cl_2$ and $NaBH_4$ as the electrocatalysts and reducing agent, respectively. The 'impregnation-reduction(I-R) method' has been investigated as a tool for the preparation of electrocatalysts for water electrolyzer by varying the concentration of reducing agent and reduction time at fixed concentration of platinum salt, 5 mmol/L. Pt-SPE electrocatalysts prepared by non-equilibrium I-R method showed the lowest cell voltage of 2.17 V at reduction time, 90 min and with concentration of reducing agent 0.8 mol/L and the cell voltage with those by equilibrium I-R method was 2.42 V at reduction time, 60 min and with concentration of reducing agent 0.8 mol/L. The cell voltage were obtained at a current density $1\;A/cm^2$ and $80^{\circ}C$. In water electrolysis, hydrogen production efficiency by Pt-SPE electrocatalyst is 68.2% in case of non-equilibrium I-R method and 61.2% at equilibrium I-R method.

• 한국위험물학회지
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• 제2권1호
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• pp.31-37
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• 2014

Since the unprecedented hydrogen fluoride leak accident in 2012, there has been growing demand for customized technical information for rapid response and chemical accident management agencies including the Ministry of Environment, the National Emergency Management Agency, and the National Police Agency need more information on chemicals and accident management. In this regard, this study aims to provide reliable technical data and guidelines to initial response agencies, similar to accident management technical reports of the US and Canada. In this study, we conducted a questionnaire survey and interviews on initial response agencies like fire stations, police stations, and local governments to identify new information items for appropriate initial response and improvements of current guidelines. We also collected and reviewed the Canada's TIPS, US EPA's hydrogen fluoride documents, domestic and foreign literature on applicability tests of control chemicals, and interview data, and then produced items to be listed in the technical guidelines. In addition, to establish database of on-site technical information, we carried out applicability tests for accident control data including ① emergency shut down devide, safety guard, shut down valve, ground connection, dyke, transfer pipe, scrubber, and sensor; ② literature and field survey on distribution type and transportation/storage characteristics (container identification, valve, ground connection, etc.); ③ classification and identification of storage/transportation facilities and emergency management methodslike leak prevention, chemicals control, and cutoff or bypass of rain drainage; ④ domestic/foreign analysis methods and environmental standards including portable detection methods, test standards, and exposure limits; and ⑤ comparison/evaluation of neutralization efficiency of control chemicals on toxic substances.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.817-820
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• 2009

Research on usage of syngas produced by waste gasification is on going all around the world. Syngas which consists of $H_2$, CO, $CO_2$, $N_2$, has different combustion characteristics from current city gas; due to distinct flame propagation speed of the fuel, syngas has different spark timing and air fuel ratio at maximum generating efficiency. This is why finding both the optimum point of spark timing and air fuel ratio is so important in order to improve thermo efficiency and secure stable running of gas generated by relatively low heating value syngas. Moreover, since emission of $NO_x$ is strictly regulated, it is important to operate lean burn condition that reduces NOx emission.

• 대한화학회지
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• 제57권3호
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• pp.316-321
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• 2013

Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickle (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electro-coagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 에너지변화시스템부문
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• pp.266-268
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• 2009

In this paper, authors deal with a power conditioning system (PCS) of high efficiency for a proton exchange membrane fuel cell (PEMFC) generation system. Fuel cells are a direct current (DC) power generators. They generate electricity through an electrochemical process that converts the energy stored in a fuel directly into electricity. Fuel cells have many benefits, which produce no particulate matter, nitrogen or sulfur oxides. And they have few moving parts and produce little or no noise. When fueled by hydrogen, they yield only heat and water as byproducts. Their wide application can reduce our dependence on fossil fuels and foreign sources of petroleum. This paper studies on a novel PCS circuit topology of high efficiency using in PEMFC generation system The controlling switches in the PCS is operated to soft switching. Some digital simulation results and experimental results for the proposed PCS is confirmed to the validity of the analytical results.

• 마이크로전자및패키징학회지
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• 제27권4호
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• pp.11-17
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• 2020

Copper has been proved to be the best catalyst for electrochemical CO2 reduction reaction, however, for optimal efficiency and selectivity, its performance requires improvements. Electrochemical CO2 reduction reaction (RR) using CuO nanowire electrode was performed with different concentrations of KHCO3 electrolyte (0.1 M, 0.5 M, and 1 M). Cu(OH)2 was formed on Cu foil, followed by thermal-treatment at 200℃ under the air atmosphere for 2 hrs to transform it to the crystalline phase of CuO. We evaluated the effects of different KHCO3 electrolyte concentrations on electrochemical CO2 reduction reaction (RR) using the CuO nanowire electrode. At a constant current (5mA), low concentrated bicarbonate exhibited a more negative potential -0.77 V vs. Reversible Hydrogen Electrode (RHE) (briefly abbreviated as VRHE), while the negative potential reduced to -0.33 VRHE in the high concentration of bicarbonate solution. Production of H2 and CH4 increased with an increased concentration of electrolyte (KHCO3). CH4 production efficiency was high at low negative potential whereas HCOOH was not influenced by bicarbonate concentration. Our study provides insights into efficient, economically viable, and sustainable methods of mitigating the harmful environmental effects of CO2 emission.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.289-296
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• 2014

Here, we have studied the effect of water added electrolyte on the photovoltaic performance of dye-sensitized solar cells (DSSCs). It was found that open-circuit voltage ($V_{oc}$) increased and short-circuit current density ($j_{sc}$) decreased with the increase of the amount of added water in the electrolyte of the DSSCs. Electrochemical impedance spectroscopy (EIS) study showed that the electrolyte with added water shifted the dye loaded $TiO_2$ conduction band upward that eventually increased $V_{oc}$ of the cells. On the other hand, the upward shift of $TiO_2$ conduction band decreased the driving force for the electron injection from the lowest unoccupied molecular orbital (LUMO) of the dye molecules to the conduction band of $TiO_2$ that resulted in decreased $j_{sc}$.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.136-147
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• 2015

Dead-ended operation of Proton Exchange Membrane Fuel Cell(PEMFC) provides the simplification of fuel cell systems to reduce fuel consumption and weight of fuel cell. However, the water accumulation within the channel prohibits a uniform supply of fuel. Optimization of the purge strategy is required to increase the fuel cell efficiency since fuel and water are removed during the purge process. In this study, we investigated the average voltage output which depends on two interrelated conditions, namely, the supply gas pressure, purging valve open time. In addition, flow visualization was performed to better understand the water build-up on the anode side and cathode side of PEMFC in terms of a variety of the current density. We analyzed the correlation between the purge condition and water flooding.

• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.363-369
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• 2018

This paper considers the alternative way to mitigate cost for REC instead of Photovoltaic (PV) panels with Energy Storage System (ESS). This study starts from an economic analysis of a 1 megawatt PV system without ESS. Several assumptions have been applied in consideration of the current domestic situation. Based on this result, the economic efficiency of PV with ESS improved. However, the reliance on government subsidies was very high. The alternative way to cover the fluctuation power from renewable energy was reviewed with economical and technical way. In case the natural gas engine applied to PV, the IRR and Levelized Cost of Electricity (LCOE) can be improved without ESS. And if small amount of additional REC, the IRR can be improved up to investment level.