• Transactions of the Korean hydrogen and new energy society
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• v.33 no.1
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• pp.113-120
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• 2022

Quantum dots (QDs) are attractive photosensitizer candidates for application not only in solar cells but also in solar hydrogen generation. For the prepartion of highly efficient QD-sensitized photoelectrodes, it is important to reduce electron recombination at the photoanode/electrolyte interface. Here, we study on the coating condition of ZnS passivation layers on the photoanodes in QD-sensitized solar cells (QDSCs). The ZnS passivation layers are coated by successive ionic layer adsorption and reaction method, and as the cation precursor, zinc acetate and zinc nitrate are empolyed. Due to the higher pH of cation precursor solution, the ZnS loading is improved when the zinc acetate is used, compared to the zinc nitrate. This improved loading of ZnS leads to the reduced electron recombination at the surface of photoanodes and the enhaced conversion efficiency of QDSCs from 6.07% to 7.45%.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.1
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• pp.54-61
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• 2007

The influences of pH were investigated for anaerobic hydrogen gas production under the constant pH condition ranged from pH 3 to 10. Carbon dioxide and hydrogen gas were main components of the gas but methane was not detected in the produced gas when sucrose was added in enrichment medium. When the modified Gompartz equation was applied for the statistical analysis of experimental data, a hydrogen production potential and maximum gas production rate at pH 5 were 1,182 mL and 112.46 mL/g dry wt biomass/hr. The hydrogen conversion ratio was 22.56%. The butyrate/acetate ratios at pH 5 and pH 6 are 1.63 and 0.38. Higher butyrate/acetate ratio produced more hydrogen gas generation. The Haldane equation model was used to find the optimum pH and fitted well with the experimental data$(r^2=0.98)$. The optimum pH and specific hydrogen production were 5.5 and 119.61 mL/g VSS/h.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.13-29
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• 2016

In this study, we analyzed the causes of major faults in the biogas plant through the case of gas engine failure when cogenerating electricity and heat using biogas as a fuel in the actual sewage treatment plant and suggested countermeasures. Hydrogen sulfide in the biogas entering the biogas engine and water caused by intermittent malfunction of the water removal system caused intercooler corrosion in the biogas engine. In addition, the siloxane in the biogas forms a silicate compound with silicon dioxide, which causes scratches and wear of the piston surface and the inner wall of the cylinder liner. The substances attached to the combustion chamber and the exhaust system were analyzed to be combined with hydrogen sulfide and other impurities. It is believed that hydrogen sulfide was supplied to the desulfurization plant for a long period of time because of the high content of hydrogen sulfide (more than 50ppm) in the biogas and the hydrogen sulfide was introduced into the engine due to the decrease of the removal efficiency due to the breakthrough point of the activated carbon in the desulfurization plant. In addition, the hydrogen sulfide degrades the function of the activated carbon for siloxane removal of the adsorption column, which is considered to be caused by the introduction of unremoved siloxane waste into the engine, resulting in various types of engine failure. Therefore, hydrogen sulfide, siloxane, and water can be regarded as the main causes of the failure of the biogas engine. Among them, hydrogen sulfide reacts with other materials causing failure and can be regarded as a substance having a great influence on the pretreatment process. As a result, optimization of $H_2S$ removal method seems to be an essential measure for stable operation of the biogas engine.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.381-395
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• 2023

This paper presents a GIS-based site suitability analysis for a smart hydrogen energy plant in the Gangwon-Do region, South Korea. A GIS-based multi-criteria decision analysis (MCDA) was implemented in this study to identify the most suitable sites for the development of smart hydrogen energy plants. The study utilizes various spatial data layers, including hydrogen generation potential and climatic conditions, environmental and topographic conditions, and natural catastrophic conditions, to evaluate the suitability of potential sites for the hydrogen energy plant. The spatial data layers were then used to rank and prioritize the sites based on suitability. The findings revealed that 4.26% of the study area, or 712.14 km², was suitable for constructing smart hydrogen energy plants. Some regions of Cheorwon-gun, Chuncheon-si, Wonju-si, Yanggu-gun, Gangneung-si, Hoengseong-gun, and near the coastal region along the east coast were found to be suitable for solar and wind energy utilization. The proposed MCDA provides a valuable tool for decision-makers and stakeholders to make informed decisions on the location of smart hydrogen energy plants and supports the transition to a sustainable and low-carbon energy system. Decision-makers can use the results of this study to select suitable sites for constructing smart hydrogen energy plants.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3241-3246
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• 2007

Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed with hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of the syngas to the performance of a gas turbine in a combined cycle power plant. For this purpose, a commercial gas turbine is selected and its performance characteristics are analyzed with three different fuels, i.e., natural gas ($CH_4$), syngas and hydrogen. It is found that different heating values of those fuels and chemical compositions in their combustion gases are the causes in the different performance characteristics.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.328-339
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• 2010

A new gasification model for coal char was developed considering the effects of pore structure and solid reaction product (ash) and compared with conventional models. Among various parameters reflecting microscopic pore structure, initial pore surface per unit volume of char was found to have the largest effect on carbon conversions. Reaction studies showed that the proposed model can predict carbon conversion more accurately over a broader range of reaction degree compared to the conventional models. Therefore the model proposed in this study would be useful for the design of pilot or commercial scale gasifiers.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.3
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• pp.249-254
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• 2013

The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with other coal fueled power generation system. The aim of this study is to confirm the feasibility of using bio gas in coal feeding system and syngas recirculation system. The effects of using bio gas in the gasifier on the syngas composition were investigated through simulations using the Aspen Plus process simulator. It was found that these changes had an influence on the syngas composition of the final stream and bio gas can be used in a gasifier system.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.227-230
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• 2005

There is a worldwide interest In the development and commercialization of PEMFCs for vehicular and stationary applications. The major problem in the practical use of PEMFCs is the deactivation of the Pt anode electrocatalyst by the adsorption of carbon monoxide. Therefore, intensive work has been devoted to finding electrocatalysts that are tolerant to CO in hydrogen at operating temperatures bellow $100^{\circ}C$. Also, DMFC is considered to be one of the most promising technologies for energy generation. But, the most important problem associated with the DMFC is the slow reaction rate of methanol oxidation and the second major problem is fuel crossover. So, the performance of a state-of-the-art DMFC is considerably lower than that of hydrogen-fuelled PEMFC. In this research, the preparation and characterization of electrode materials will be introduced. Also, some electrochemical techniques for the characterization of PEMFCs will be presented.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.558-559
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• 2008

본 논문은 미 일리노이 주립대 어바나-샴페인 캠퍼스에서 주로 군사용 응용 관련하여 개발 중인 마이크로 PEM 연료전지 시스템 개발에 대한 논문이다. 본 연구는 수소 저장 장치까지 포함하여 1 $mm^3$의 초소형 연료전지 시스템을 목표로 진행 중이며 본 논문은 이러한 진행 과정 중 화학적 하이드라이드 기반의 수소 발생기와 10 $mm^3$의 시스템 개발 과정에 대해 보고한다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.561-564
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• 2007

FCEV uses electric energy which generated from the reaction between Hydrogen and Oxygen in fuel cell stack as driving force. As fossil fuels are exhausted, fuel cell is regarded as a potent substitute for next generation energy source, and thus, most of car-makers make every efforts to develop fuel cell electric vehicle (FCEV). In addition, fuel cell is also beneficial in aspect of environment, because only clean water is produced during chemical reaction process instead of harmful exhausted gas. Generally, Hydrogen is supplied from high-pressured fuel tank, and air blower (or compressor) supply Oxygen by pressurizing ambient air. Air blower which is driven by high speed motor consumes about $7{\sim}8$ % of energy generated from fuel cell stack. Therefore, the efficiency of an air blower is directly linked with the performance of FCEV. This study will present the development process of an air blower and its consisting parts respectively.