• 한국자동차공학회논문집
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• 제17권1호
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• pp.137-145
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• 2009

The steady-state kinetics of the selective catalytic reduction (SCR) of $NO_X$ with $NH_3$ has been investigated over a commercial ${V_2}{O_5}/TiO_2$ catalyst. In order to account for the influence of transport effects the kinetics are coupled with a fully transient two-phase 1D+1D monolith channel model. The Langmuir-Hinshelwood (L-H) mechanism is adopted to describe the steady-state kinetic behavior of the ${V_2}{O_5}/TiO_2$ catalyst. The reaction rate expressions are based on previously reported papers and are modified to fit the experimental data. The steady-state chemical reaction scheme used in the present mathematical model has been validated extensively with experimental data of selective $NO_X$ reduction efficiency for a wide range of inlet conditions such as space velocity, oxygen concentrations, water concentration, and $NO_2/NO$ ratio. The parametric investigations are performed to examine how the $NH_3$ slip from a SCR $DeNO_X$ catalyst and the conversion of $NO_X$ are affected by the reaction temperature, $NH_3/NO_X$ feed ratio, and space velocity for feed gas compositions with $NO_2/NO_X$ ratios of 0 and 0.5.

• 한국해양공학회지
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• 제22권3호
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• pp.82-88
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• 2008

The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

• 한국수소및신에너지학회논문집
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• 제29권3호
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• pp.299-305
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• 2018

The domestic label fuel economy measurement method is the same as the North American measurement method. The results of two test modes (city [FTP-75 mode], highway [HWFET mode]) are calculated to be equivalent to the final fuel economy value calculated as the result of five test modes reflecting various environmental conditions and driving patterns 5-cycle correction formula is used. In this study, we tried to find out that the difference between the domestic label fuel economy of the vehicle and the real road fuel economy felt by the driver compared to the new vehicle condition as the mileage increases. Using domestic label fuel economy measurement method, Four gasoline vehicles and four diesel vehicles were tested for the fuel economy of a new vehicle with a mileage of 150 km or less and domestic fuel economy test $6,500{\pm}1,000km$ durability condition and 15,000 km durability. It is confirmed that the certain portion (6,500 km endurance vehicle) The increase in mileage did not affect the fuel economy or the emission gas significantly, indicating that vehicle durability was limited.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.418-424
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• 2015

국제해사기구 해양환경보호위원회는 2016년 1월 1일부터 배출통제지역을 통항하는 선박에 대해서 Tier III를 적용하여 질소산화물 배출 규제를 더욱 강화하기로 결정하였다. 본 논문에서는 질소산화물 배출 저감을 위한 연구의 일환으로 한국해양대학교 실습선 한바다호를 이용하여 실제 운항 중에 주기관을 단일분사와 이단지연분사의 두 가지 조건으로 운전하여 부하별 배기가스, 실린더 압력, 연료소모량 등을 계측하였다. 그 결과 두 가지 운전조건 모두 엔진의 부하가 증가할수록 질소산화물과 이산화탄소 배출량도 함께 증가하는 경향을 보였으며, 일산화탄소의 농도는 감소하였다. 또한 이단지연분사 시에는 최대폭발압력이 약 10% 이상 감소하였고, 이로 인해 배기가스 내 질소산화물의 농도는 약 25~30% 정도 감소하였다. 하지만 질소산화물 배출 저감의 긍정적인 결과에 반하여 연료소비율이 약 3~5% 정도 증가하는 상반관계가 확인되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2874-2879
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• 2008

The Selective catalytic reduction(SCR) system is a highly-effective device of $NO_x$ reduction for diesel engines. Generally, the ammonia($NH_3$) generated from a liquid urea-water solution is used for the reductant. The ideal ratio of $NH_3$ molecules to $NO_x$ molecules is 1:1 based on $NH_3$ consumption and having $NH_3$ available for reaction of all of the exhaust $NO_x$. However, under the too low and too high temperature condition, the $NO_x$ reduction efficiency becomes lower, due to temperature window. And space velocity also affects to $NO_x$ conversion efficiency. This paper reviews a laboratory study to evaluate the effects of $NO_x$ and $NH_3$ concentrations, gas temperature and space velocity on the $NO_x$ conversion efficiency of the SCR system. The maximum conversion efficiency of $NO_x$ was indicated when the $NH_3$ to $NO_x$ ratio was 1.2 and the space velocity was $60,000\;h^{-1}$. The results of this paper contribute to improve overall $NO_x$ reduction efficiency and $NH_3$ slip.

• Corrosion Science and Technology
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• 제9권6호
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• pp.310-316
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• 2010

Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. In this case, filler metals having a high corrosion and wear resistance such as stellite 6, Inconel 625 and Inconel 718 are mainly being used for repair welding. However it has been often happened that piston crown on the ship,s job site is being actually inevitably welded with mild filler metals. Therefore in this study, filler metals such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal, and corrosion property of their weld metals in the case of post weld heat treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 0.1% $H_2SO_4$ solution. Corrosion resistance of the weld metal of E4301 was better than the other weld metals in the case of no heat treatment, however, its resistance was considerably decreased with post weld heat treatment(annealing:$625^{\circ}C$, 2 hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by post weld heat treatment.

• 동력기계공학회지
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• 제6권1호
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• pp.20-26
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• 2002

The purpose of this study is preventing the stick, scuffing, scratch between piston and cylinder in advance, and obtaining data for duration test in actual engine operation. The temperature gradient in cylinder bore according to coolant temperature were measured using $1.5{\ell}$ class diesel engine. 20 thermocouples were installed 2mm deep inside from cylinder wall near top ring of piston in cylinder block, at which points major thermal loads exist. It is suggested as proper measurement points for engine design by industrial engineers. Under full load and $70^{\circ}$, $80^{\circ}C$ and $90^{\circ}C$ coolant temperature conditions, the temperature in cylinder block and engine oil increased gradually according to the increase of coolant temperature, the siamese side temperature of top dead center is $142^{\circ}C$ in peripheral distribution, that is about $20^{\circ}C$ higher than that at thrust, anti-thrust, and rear side temperature, respectively. The maximum pressure of combustion gas in $70^{\circ}C$ coolant temperature is about 2 bar lower than those of $80^{\circ}C$ and $90^{\circ}C$ coolant temperature. The engine torque in $80^{\circ}C$, $90^{\circ}C$ coolant temperature condition is about 4.9Nm higher than that of $70^{\circ}C$ coolant temperature.

• Tribology and Lubricants
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• 제34권6호
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• pp.292-299
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• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.654-660
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• 2018

The dependence on global fossil fuels has been gradually reducing all over the world. Some countries which recognized the important of environmental values were joining to carry out international GHG goals. Our country has also participated with high targets (37% reduction compared to BAU 2030 years). So we need to supply materials of lower GHG value such as a bio-diesel. Bio-alcohol is one of the similar bio-fuels that can be reducing GHG. A lot of countries had tried to commercialize through various R&D for bio-alcohol. In this study, we analyzed the fuel characteristics of bio-alcohol fuel produced by domestic technology. And we evaluated a possibility to use as vehicle fuel through mixing of bio-alcohol and gasoline. The mixed fuels were satisfied with 2.3 wt% of oxygen content that is standard of the petroleum and petroleum alternative fuel business Act. We tried to evaluate a emission characteristic of vehicle by mixed fuel. In accordance with the results we tried to find a correlation between fuel and emission.

• 전기화학회지
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• 제22권1호
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• pp.1-12
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• 2019

암모니아 생산은 이전부터 비료, 식량과 관련되어 많은 연구가 이루어져 왔는데, 최근 신재생 에너지에 대한 관심이 커짐에 따라 암모니아 또한 에너지로서 내연기관이나 연료전지로 활용이 기대되어 더 많은 연구가 활발히 이루어 지고 있다. 하지만 암모니아를 생성하기 위해서 하버-보쉬법을 사용하는데, 150-300기압과 $350-550^{\circ}C$ 이상의 높은 압력과 온도가 필요하므로 지구 에너지의 1-2%를 사용할 만큼 암모니아 생산에 많은 에너지가 소모되며, 주로 화석연료가 사용된다. 위와 같은 반응에 사용되는 에너지를 줄임으로 이산화탄소 배출량을 줄여 환경문제에도 대응할 수 있기 때문에 반응온도 및 압력을 줄이는 노력이 필요하다. 본 총설에서는 암모니아를 생산하기 위한 방법 중 특히 상온, 상압에서의 전기화학적 질소환원반응 결과들을 소개한다. 실험 결과뿐만 아니라 밀도범함수 계산을 통하여 전기화학적 질소환원반응 메커니즘 연구가 많이 되었으며, 더 많이 전기화학반응에 참여할 수 있도록 하는, 나노 와이어, 다공성 전극과 같은 나노구조화 전극설계에 대한 다양한 연구 결과들 또한 제시한다.