• 한국대기환경학회지
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• 제14권3호
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• pp.261-266
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• 1998

Recently, air pollution is increased according to increase of vehicle. So many countries are studying about DOC for diesel emission decrease. However, there are many difficulty in applying to DOC . In this study, SOx exhaust gas equipped with DOC was studied and we obtained several test results as following. First, in diesel oxidation catalyst, additives such as Pt is very effective for 503 and sulfate. Second, the oxidative activity for 502 has decreased to add such as Pt and the decrease of 502 is effect for the reduction of PM in high temperature . And finally, in high temperature, concentration of SOx is increased and temperature is affected by process from SOB to 503, whereas engine performance and fuel consumption are not affected by equipped DOC.

• 대한조선학회지
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• 제8권1호
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• pp.95-102
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• 1971

Since the fuel oil of the bunker C grade, which is commonly burnt in the large marine diesel engine, causes the corrosive wear of cylinder liners and piston rings, a cylinder oil of high alkality is frequently used to prevent the wear. This practice, however, brings us an another problem to cause the abnormal wear. In this study the author made an investigation of the mechanism of the abnormal wear by the experiments surveying the influences of the alkality of a cylinder oil and the temperature of cylinder wall on the wear. The major results obtained from this study are as follows; A cylinder oil of low alkality is clearly effective for the preventation of the abnormal wear. Therefore, it is recommended that, prio to using a cylinder oil of high alkality, a cylinder oil of low alkality should be used until bringing an end to the initial wear. It is also observed that the abnormal wear depends largely on the temperature of the cylinder wall, that is, the higher the temperature goes up the severer the wear grows.

• 유기물자원화
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• 제28권1호
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• pp.83-95
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• 2020

폐기물을 이용한 공공 자원회수시설, BIO-SRF를 이용한 민간 열원시설 열에너지를 효율적으로 활용함에 있어 투자 대비 회수 기간의 경제성 문제가 대두 되었고, 이로 인하여 기존에 통상적으로 설계 시공 운영 되었던 온도, 압력 조건 범위값을 넘어서 실현 가능한 최적의 온도, 압력 조건의 열원 설비가 필요하게 되었다. 본 연구에서는 국내에서 운영 중인 열원시설을 대상으로 온도와 압력 조건에 따른 모델링을 통하여 에너지 전력 생산량을 분석하였고, 도출된 에너지 전력 생산량을 통하여 온실가스 배출량 감축 특성을 연구하였다. 최종적으로 폐기물 및 바이오매스 연료를 이용한 열에너지 생산시설의 효율적인 에너지 활용을 위해서는 고온의 온도와 고압의 압력 생산시 효율적인 에너지 생산이 이루어지고 경제성 있는 투자와 회수로 이루어지리라 판단된다.

• 에너지공학
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• 제25권1호
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• pp.113-121
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• 2016

고분자 전해질 연료전지는 운전온도에 따라 효율과 출력이 변화하기 때문에 $65^{\circ}C{\sim}75^{\circ}C$정도의 적정 운전온도를 유지하기 위한 냉각시스템을 필요로 한다. 따라서 PEMFC 운전온도를 유지하기 위한 냉각시스템 및 이를 위한 제어로직을 적용할 필요가 있다. HILS는 이러한 냉각시스템 제어로직을 검증하고 연구하기 위한 방법 중 하나이다. 본 논문에서는 냉각수 제어 알고리즘 연구를 위해 HILS 시스템을 구성하였다. HILS 시스템 모델은 PEMFC, 열교환기 및 온도와 관련한 외부환경 모델로 구성되며, HILS 시스템의 하드웨어는 삼방밸브, 펌프, 열교환기로 이루어진다. 이러한 HILS를 활용하여 냉각시스템 제어 효율 향상을 위한 제어우선순위 및 제어 대상온도 설정에 대한 연구를 수행하였다. 1차 냉각회로의 삼방밸브를 우선제어대상으로 설정하고, 2차 냉각회로의 온도제어성능 보정을 위해 2차 냉각회로 삼방밸브의 개도율 하한값을 PEMFC 출력과 2차 냉각회로 냉각수 온도의 함수로 작성하여 온도제어성능을 보상할 수 있도록 하였다. 그 결과 안정적인 PEMFC 온도 제어성능을 확인하였다.

• 한국세라믹학회지
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• 제56권2호
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• pp.130-145
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• 2019

Widespread commercialization of solid oxide fuel cells (SOFCs) is expected to be realized in various application fields with the advent of cost-effective fabrication of cells and stacks in high volumes. Cost-reduction efforts have focused on production yield, power density, operation temperature, and continuous manufacturing. In this article, we examine several issues associated with processing for SOFCs from the standpoint of the bimodal packing model, considering the external constraints imposed by rigid substrates. Optimum compositions of composite cathode materials with high volume fractions of the second phase (particles dispersed in matrix) have been analyzed using the bimodal packing model. Constrained sintering of thin electrolyte layers is also discussed in terms of bimodal packing, with emphasis on the clustering of dispersed particles during anisotropic shrinkage. Finally, the structural transition of dispersed particle clusters during constrained sintering has been correlated with the structural stability of thin-film electrolyte layers deposited on porous solid substrates.

• 대한기계학회논문집B
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• 제33권12호
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• pp.1022-1030
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• 2009

Numerical analysis was carried out to investigate the effect of GDL (Gas diffusion layer) porosity on the performance of PEMFC (proton exchange membrane fuel cell). A complete three-dimensional model was chosen for single straight channel geometry including cooling channel. Main emphasis is placed on the heat and mass transfer through the GDL with different porosity. The present numerical results show that at high current densities, the cell voltage is influenced by the GDL porosity while the cell performance is nearly the same at low current densities. At high current densities, low value of GDL porosity results in decrease of the fuel cell performance since the diffusion of reactant gas through GDL becomes slow with decreasing porosity. On the other hand, for high GDL porosity, the effective thermal conductivity becomes low and the heat generated in the cell is not removed rapidly. This causes the temperature of fuel cell to increase and gives rise to dehydration of the membrane, and ultimately increase of the ohmic loss.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.406-409
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• 2012

Recently, enormous research efforts have been focused on the development of non-precious catalysts to replace Pt for electrocatalytic oxygen reduction reaction (ORR), and to reduce the cost of proton exchange membrane fuel cells (PEMFCs). In recent years, heteroatom (N, B, and P) doped carbon nanostructures have been received enormous importance as a non-precious electrode materials for oxygen reduction. Doping of foreign atom into carbon is able to modify electronic properties of carbon materials. In this study, nitrogen and boron doped carbon nanostructures were synthesized by using a facile and cost-effective thermal annealing route and prepared nanostructures were used as a non-precious electrocatalysts for the ORR in alkaline electrolyte. The nitrogen doped carbon nanocapsules (NCNCs) exhibited higher activity than that of a commercial Pt/C catalyst, excellent stability and resistance to methanol oxidation. The boron-doped carbon nanostructure (BC) prepared at $900^{\circ}C$ showed higher ORR activity than BCs prepared lower temperature (800, $700^{\circ}C$). The heteroatom doped carbon nanomaterials could be promising candidates as a metal-free catalysts for ORR in the PEMFCs.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.83-88
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• 2003

The concept of lean-premixed combustion in gas turbine combustor operation has become a standard in recent years as an effective means to meet stringent environmental standards on NOx emissions. Various types of air-fuel premixer, which affect greatly NOx emission and stability of lean-premixed low NOx combustor, were investigated experimentally to reduce the NOx emission. One type of the premixers is selected by experiments and applied it to 70kW class lean-premixed gas turbine combustor. The exit temperature and emissions of CO and NOx were measured with equivalence ratios at ambient pressure. From the results, the emissions of CO and NOx were influenced by the type of air-fuel premixer. As the mixing length of air and fuel is longer, the NOx and CO emission were decreased in the primary reaction zone. Compared with of conventional combustor, the lean-premixed low NOx combustor has low NOx emission characteristics.

• 한국가스학회지
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• 제11권4호
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• pp.12-16
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• 2007

천연가스 자동차에 탑재되어 있는 연료압력 레귤레이터는 연료분사시스템의 압력을 일정하게 유지하는 역할을 한다. 연료압력의 정확한 제어는 천연가스 자동차가 가지고 있는 높은 효율성과 청정성을 십분 활용하기 위해서 반드시 필요한 사항이다. 본 연구에서는 천연가스 레귤레이터의 성능을 정확하게 평가할 수 있는 고압실험장치를 구축하였으며, 이 장치를 이용하여 두 가지 방식의 천연가스 레귤레이터를 평가하고 상호 비교를 하였다. 레귤레이터 밸브시스템의 설계에 따라 여러 가지 레귤레이터 성능 특성 중 동적응답과 Creep특성이 영향을 많이 받는 것으로 나타났으며, 레귤레이터 입구 압력이 높을 경우 출구 가스의 온도가 급격히 감소하는 것으로 나타남으로써 아이싱문제를 효과적으로 방지할 수 있는 방안이 마련되어야 함을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2454-2463
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• 2021

The objective of this research is to the use of americium (AmO₂) as a burnable absorber effectively instead of conventional gadolinium (Gd₂O₃) for VVER-1200 reactor by analyzing its impacts on reactivity, power peaking factor (PPF), safety factor, and quality of the spent fuel. The assembly is burned to 60 GWd/t by using SRAC-2006 code and JENDL-4.0 data library for finding the optimum amount and effective way of using AmO₂ as a burnable absorber. From these studies, it is found that AmO₂ can decrease the excess reactivity like Gd₂O₃ without changing the criticality life span and enrichment of ²³⁵U. A homogeneous mixture of the 0.20% AmO₂+ 4.95% enriched UO₂ fuel rod (model MF-4) decreases the PPF than the reference assembly. The use of AmO₂+UO₂ in the integral burnable absorber (IBA) rod or the outer layer could also decrease the PPF up to 10 GWd/t but increases rapidly after 30 GWd/t, which could be a safety threat. The fuel temperature coefficient and void coefficient of the model MF-4 are the same as the reference assembly. In addition, 22% of initially loaded Am are burning effectively and contributing to the power production.