• 대한기계학회논문집B
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• 제27권11호
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• pp.1548-1562
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• 2003

This paper is the first of several companion papers which compare the methods of Air-fuel ratio determination. There are many methods which calculate Air-Fuel ratio from exhaust emission. Most of them are based on the simple chemical equations, which use balance of atom, and the error of the calculation is negligible as far as the instrumentation accuracy is guaranteed. They assume homogeneous mixture and complete combustion to the extent of oxygen availability. Because of these simple assumptions, they cannot offer the information about the fuel distribution state and the malfunction of instrument. For these limitations, Eltinge offered new one based on stricter mathematical model. This result coincides with the others very well and gives more information about the mixture state and instrumentation. Consequently this might be a general solution for Air-fuel ratio determination and exhaust composition. The objects of the calculation, however, were not commercial fuels except gasoline and the compensation method of unburned hydrocarbon was not appropriate to recent analyzer. Moreover he did not consider the fuel which contains oxygen, such as methanol, ethanol and blend of gasoline-alcohol. In this paper, Eltinge chart is expanded to the arbitrary fuel composition as the reference exhaust compositions for the purpose of further discussions about Air-fuel ratio determination methods and the charts fur gasoline, diesel, methanol, M85, liquefied petroleum gas(LPG), natural gas(NG), propane, butane are illustrated.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.92-99
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• 2013

High oil price and global warming problem are being continued all over the world. For this reason, fuel economy and emission of greenhouse gas are regulated by law in many countries. Therefore many companies are researching and producing hybrid electric vehicles (HEVs) which substitute conventional internal combustion engine vehicle. However, these researches and productions are restricted to mainly passenger cars. Because of cost and physical problems, commercial vehicles are difficult to evaluate fuel economy. So simulations are important and it is necessary to know how sensitive parameters that enter into simulation affect. In this paper, forward simulations using AVL Cruise were conducted for analysis of fuel economy for parallel hybrid bus and were repeated by changing each parameter. Based on these results, root mean square errors (RMSE) are calculated for analysis of fuel economy sensitivity. The number of target parameters are 15. These parameters were classified with high and low sensitivity parameter relatively.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.297-308
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• 2017

One of the major engine thermal management system(TMS) strategies for improving fuel economy is to operate the engine in high temperatures. Therefore, this work performed a numerical and experimental study to examine the effect of several different STOs(Starting Temperature of Opening) of wax-thermostat, ranging from $85^{\circ}C$ to $105^{\circ}C$, of gasoline engine on fuel economy and emission characteristics. In this study, a gasoline car equipped with waxthermostat was tested and simulated under FTP-75 and HWFET mode. CRUISE $M^{TM}$ was used to simulate vehicle dynamics, transient engine performance and TMS. The test results showed fuel savings for both drive cycles due to higher STO of $100^{\circ}C$, which is slightly worse than that of $90^{\circ}C$ and amounts between 0.34 and 0.475 %. These controversial results are attributed to experimental errors and uncertainty. The computational results for three STOs, $85^{\circ}C$, $95^{\circ}C$ and $105^{\circ}C$, showed that fuel savings attributed to the application of higher STOs of $95^{\circ}C$ and $105^{\circ}C$ are relatively small and range from 0.306 to 0.363 %. It is also found that the amount of HC and CO emissions from the tailpipe tends to decrease with higher engine coolant temperature because of faster catalyst light-off and improved combustion.

• Asian Journal of Atmospheric Environment
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• 제6권1호
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• pp.14-22
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• 2012

This paper is focused on the comprehensive and detailed interpretation for the chemical transformation of individual Asian dust (hereafter called "AD") particles during long-range transport from source regions to receptor area. A multi-stage particle sampler was operated at a ground-based site in Taean, Korea directly exposed to the outflow of air masses from China during AD period in April 2003. Both quantitative and qualitative analyses for size-classified individual particles were carried out by a microbeam X-ray fluorescence (XRF) method and a microbeam Particle Induced X-ray Emission (micro-PIXE), respectively. Among major characteristic elements, the elemental masses of soil derived components, sulfur, and chloride varied as a function of particle size showing the monomodal maximum with a steeply increasing at 3.3-4.7 ${\mu}m$ particle size. Although the details on chemical composition of AD particle collected on a straight line from source area to our ground-based site are needed, a large amount of Cl coexisted in and/or on AD particles suggests that AD particles collected in the present study might be actively engaged in chemical transformation by sea-salt and other Cl containing pollutants emitted from the China's domestic sources. Through the statistical analyses it was possible to classify individual AD particles into six distinct groups. The internally mixed AD particles with Cl, which has various sources (e.g., sea-salt, coal combustion origin HCl, gaseous HCl derived from the adsorption of acids to sea-salt, and Cl containing man-made particles) were thoroughly fractionated by the elemental spectra drivened by the double detector system of micro-PIXE.

• 한국응용과학기술학회지
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• 제32권3호
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• pp.588-598
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• 2015

최근 정부는 신재생에너지 연료 혼합 의무화 제도(RFS)와 신재생에너지 공급 의무화제도(RPS)를 적극 추진하고 있어 신재생에너지 연료의 중요성은 그 어느 때보다도 부각되고 있으며 적극적인 연구가 필요한 때이다. 이의 일환으로 발전용 바이오중유 시범보급사업과 관련 연구가 활발히 진행 중에 있다. 본 연구에서는 바이오중유의 성능평가기준(안) 마련을 위해 중유와 바이오중유의 연료품질 특성 및 산업용 보일러에서 연소 후 배출되는 먼지, 배출가스의 양을 비교 연구하였다. 연구결과 바이오 중유를 사용할 경우 먼지와 황산화물 등 유해배출가스가 현저히 저감 되는 것이 밝혀졌다.

• Tribology and Lubricants
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• 제25권6호
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• pp.387-398
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• 2009

The operation condition of recently designed pistons for high power and high speed diesel engine become more severe due to the increment of combustion pressure and temperature. So, in order to overcome high temperature, the application of the mono-metal cast aluminum alloy piston featuring an enclosed cast-in open cooling gallery has increased. In this research, it is developed a PCJ (piston cooling jet) rig tester, described the test procedure and validated the performance of sample piston cooling gallery design. Then the test rig will be used for developing the design technology of piston cooling gallery. The test rig is composed with oil reservoir and pumping system, oil jet system, piston fixing and moving system, collecting oil measuring system, and data measuring and recording system. It will be measured collecting efficiencies under conditions of a few piston positions, oil jet pressures and oil viscosities for a piston cooling gallery. Furthermore, the PCJ rig tester will be used for the optimum design of the oil cooling gallery which being applied to increase the cooling efficiency of pistons in diesel engines satisfying the EURO V emission regulation and the more.

• 해양환경안전학회지
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• 제25권6호
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• pp.788-794
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• 2019

최근 지구의 기후변화는 온실가스가 원인으로 전 세계적 대기환경문제로 크게 부각되고 있다. 국내에서도 기후변화에 적극 대응하기 위한 기술개발이 꾸준히 진행되고 있다. 날씨의 이상고온으로 인한 환경에 미치는 영향과 갑작스런 집중호우가 환경에 미치는 영향을 대상으로 하였다. 우리생활 주변 대기온도가 상승하였을 때 온도변화에 의한 대기오염발생에 미치는 영향을 연구하고자 한다. 본 연구의 실험조건은 선박 디젤기관에서 회전수 1400 rpm, 1600 rpm 그리고 1800 rpm, 부하는 0 %에서 25 %씩 100 %까지 하였고, 흡기 온도변화는 20℃에서 50℃까지 구분하여 연구하였다. 연구한 결과 흡기온도가 증가함에 따라 일산화탄소 및 탄화수소는 약간 감소하였으나 연료소비율, 질소산화물, PM은 약간 증가하였다. 또한 연소온도는 큰 변화가 없었다.

• 한국환경보건학회지
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• 제32권4호
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• pp.324-335
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• 2006

Five sampling sites were selected to investigate the distribution characteristics of air pollutants with pollution sources and weather conditions in Ulsan. $SO_2,\;NO_2,\;O_3,\;CO,\;PM_{10}$ concentrations and weather conditions with time were analyzed by using several statistical methods. Also, the distribution characteristics of ambient air quality were estimated by pollution-rose and multi-regression analysis. As a result of the analysis, $NO_2,\;CO\;and\;PM_{10}$ concentrations were high in winter season, whereas $SO_2\;and\;O_3$ concentrations were high in summer season. This concentration distribution was caused by the unfavorable geographical location, which the residential area was located at the downwind direction to industrial area. From the pollution-rose, we confirmed that each pollutant influenced the downwind residential areas because of seasonal wind direction. $SO_2$ concentration has shown positive correlation of $0.2{\simm}0.3$ for $NO_2,\;PM_{10}$ and temperature, while $O_3$ concentration has shown negative correlation. Also, $NO_2$ and CO concentrations, pollutants generated by combustion, have shown positive correlation, while $O_3$ concentration and temperature have shown negative correlation. Therefore, it could be suggested that a seasonal air quality policy and a new guideline of air quality was necessary in each season with wind directions to reduce the air pollution level in Ulsan.

• Korean Chemical Engineering Research
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• 제46권3호
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• pp.506-511
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• 2008

본 연구에서는 이트륨과 유로퓸 질산수용액으로부터 솔-젤 및 연소공정에 의한 적색 형광체를 제조함에 있어, 솔-젤반응의 고찰을 통한 반응메카니즘을 해석하고, 제조된 적색형광체의 특성을 알아보고자 하였다. 무정형 구연산염 솔-젤 반응은 반응 초기에 킬레이트화 반응과 가수분해 반응이 완료되었으며, 가수분해의 진행에 따라 축합중합반응은 유기산 형성 축합중합 보다는 물 형성 축합중합반응이 더 우세하였다. 솔-젤 반응의 진행을 위해서는 이트륨(유로퓸 포함)과 젤화 작용제인 구연산 몰 비는 1 : 2 이상이 필요하였다. 솔-젤과 건조과정을 거쳐 얻은 젤 분말의 열분석 결과 형광체를 얻기 위한 소성온도는 $700^{\circ}C$ 이상이 되어야 하며, 젤 분말의 소성 시 소성온도가 증가함에 따라 생성되는 형광체의 결정도가 향상되었으며, 결정립 크기가 증가하였다. 제조된 형광체의 발광특성 분석 결과, 출발용액 내 금속이온(이트륨 및 유로퓸)의 농도, 그리고 소성온도가 증가할수록 발광세기가 증가하였다.

• 대한기계학회논문집B
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• 제34권7호
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• pp.689-696
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• 2010

디젤엔진은 높은 열효율과 우수한 연비 성능 등의 장점을 가지고 있으나, 기화된 연료와 주변 공기가 혼합된 후 착화되는 과정을 거치기 때문에 이론 공연비 영역에서는 질소산화물(NOx) 배출이 증가되는 문제점을 가지고 있다. 최근 활발히 연구되고 있는 높은 정화 효율을 가진 LNT 촉매는 희박 분위기 조건에서는 NOx를 흡장하게 되고 과농한 분위기에서는 환원 분위기 형성을 통하여 NOx를 저감시키게 된다. 희박 공연비에서 동작하는 디젤 엔진에서는 이러한 환원 과정을 이루기 위해 주기적으로 과농한 분위기를 형성해주어야만 하는데, 이러한 연구는 NOx 저감을 위해 HC를 포함한 환원제의 농도를 제어하는 기술로서 본 연구에서는 디젤을 연료로 하는 수소농후가스 발생장치를 이용하여 LNT 촉매에 환원제로서 수소농후가스를 직접 공급하는 방식으로 LNT 촉매의 NOx 저감 특성을 파악하였다.