• 한국자동차공학회논문집
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• 제14권5호
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• pp.32-38
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• 2006

Currently, due to the serious world-wide air pollution by substances emitted from vehicles, emission control is enforced more firmly and it is expected that the regulation requirements for emission will become more severe. A new concept combustion technology that can reduce the NOx and PM in relation to combustion is urgently required. Due to such social requirement, technologically advanced countries are making efforts to develop an environment-friendly vehicle engine at the nation-wide level in order to respond to the reinforced emission control. As a core combustion technology among new combustion technologies for the next generation engine, the homogenous charge compression ignition(HCCI) is expanding its application range by adopting multiple combustion mode, catalyst, direct fuel injection and partially premixed combustion. This study used a 2-staged injection method in order to apply the HCCI combustion method without significantly altering engine specifications in the aspect of multiple combustion mode and practicality by referring to the results of studies on the HCCI engine. In addition, this study confirmed the possibility of securing optimum fuel economy emission reduction in the IMEP 8bar range(which could not be achieved with existing partially premixed combustion) through forced charging, exhaust gas recirculation(EGR), compression ratio change and application of DOC catalyst.

• 한국가스학회지
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• 제13권6호
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• pp.15-20
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• 2009

대도시 대기질 개선을 위한 정부 정책에 의해 1990년대 이후 천연가스 차량의 보급 대수는 계속 증가하고 있다. 그러나 천연가스 차량은 환경면에서 유리한 대신 화재 발생 시 대형 사고가 잠재하므로 항상 안전에 대한 대책이 요구된다. 천연가스 차량에 장착되는 여러 가지 연료 부품 중 체크밸브는 연료용기에 충전된 고압의 천연가스가 연료주입구를 통해 외부로 방출되지 않도록 하는 안전장치로서 반 복사용에 따른 내구성이 보장되어야 하는 부품이다. 본 연구에서는 천연가스 차량용 체크밸브를 대상으로 반복 사용시험, 극한 떨림시험에 따른 내구성능과, 압축기 오일에 의한 밸브 씰의 영향을 평가하였다. 실험 결과 천연가스 차량에 사용되고 있는 체크밸브는 인증규정을 만족하였지만 압축기 오일에 오랫동안 노출될 경우 밸브 씰의 누설방지 기능에 문제를 발생시킬 수 있음을 확인할 수 있었다.

• 설비공학논문집
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• 제28권8호
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• pp.325-330
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• 2016

This study was conducted to develop a heating system for a fuel cell-driven electric vehicle. The system consists of a compressor, an expansion device and three heat exchangers. A conventional air source heat exchanger is used as primary heat exchanger of the system, and an additional water source heat exchanger is used as a pre-heater to supply heat to the upstream air of the primary heat exchanger. On the other hand, the third heat exchanger consists of a water-to-refrigerant heat exchanger. The heat source of the pre-heater and the water-refrigerant heat exchanger is the waste heat from the fuel cell's stack. In the experiment, the indoor and the outdoor air temperature were fixed, and the compressor speed, EEV opening and waste heat temperature were varied. The results indicate that the $COP_h$ of the proposed system is 3.01 when the system is operating at a 1,200 rpm compressor speed, 50% EEV opening, and $50^{\circ}C$ waste heat source temperature in air pre-heater operation. However, when the system uses a water-refrigerant heat exchanger, the $COP_h$ increases to up to 9.42 at the same compressor speed and waste heat source temperature with 75% EEV openings.

• 한국기계가공학회지
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• 제20권5호
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• pp.69-75
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• 2021

Fuel economy has always been a major issue for the automotive industry due to environmental concerns. In particular, it is known that only 5-20% of the energy generated in a car that mainly uses an internal combustion engine is converted to increase fuel efficiency, many methods have been proposed. Among these methods, weight reduction is most commonly used because it is the simplest and cheapest. Weight is always the main reason for energy consumption, therefore, reducing weight is the best way to increase fuel efficiency while simultaneously saving on material costs. To reduce the weight of a compressor, material substitution is used. However, aluminum (a lighter metal substitute) is more fragile than steel, therefore, structural stability must be verified through testing. In this paper, we performed a 3D analysis to investigate whether aluminum can be used without compromising structural stability. Our investigation included static analysis and thermal analysis. As a result, we found that an aluminum swash plate can be safely applied on a shaft instead of steel; it reduces weight while maintaining stability that is equal to or better than steel.

• 대한조선학회논문집
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• 제61권1호
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• pp.8-18
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• 2024

The present study concerns reduced order modeling of a marine diesel engine, which can be used for outlier detection in status monitoring and carbon intensity index calculation. Principal Component Analysis (PCA) is introduced for the reduced order modeling, focusing on the feasibility of detecting and treating nonlinear variables. By cross-correlation, it is found that there are seven non-linear data channels among 23 data channels, i.e., fuel mode, exhaust gas temperature after the turbocharger, and cylinder coolant temperatures. The dataset is handled so that the mean is located at the nominal continuous rating. Polynomial presentation of the dataset is also applied to reflect the linearity between the engine speed and other channels. The first principal mode shows strong effects of linearity of the most data channels to show the linearity of the system. The non-linear variables are effectively explained by other modes. second mode concerns the temperature of the cylinder cooling water, which shows small correlation with other variables. The third and fourth modes correlates the fuel mode and turbocharger exhaust gas temperature, which have inferior linearity to other channels. PCA is proven to be applicable to data given in binary type of fuel mode selection, as well as numerical type data.

• 대한교통학회지
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• 제20권1호
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• pp.19-38
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• 2002

일반적으로 교통운영 시스템에 대한 효과를 평가하기 위해서 구간통행 시간, 통행속도, 지정체율 등과 같은 효과척도(MOE: measure of effectiveness)가 사용된다. 그러나, 에너지에 대한 관심이 극히 높은 상황에서는 기존의 교통측면의 효과척도 이외에 에너지소모라는 효과척도가 교통운영시스템의 MOE로서 대안평가에서 점차로 중요한 영향을 발휘할 수 있다. 본 연구는 교통운영방식별 에너지효율성에 대한 평가를 위해 (기존에 주로 사용되던 효과척도로서의 구간평균속도, 구간평균통행시간, 지정체 뿐 아니라), 에너지 소모 또한 대안평가에 사용할 수 있을 것으로 판단하여, 각 대안별 에너지 소모를 상대적으로 측정하여 볼 수 이는 절차를 개발하고 상호 그 결과를 비교하고자 하였다. 이를 위해 메조모형 시뮬레이터인 Integration이 사용되었으며, HOV 차로 운영, 신호 최적화, 차로 확장, ITS 적용에 대한 대안의 평가를 수행하였다. 이중ITS의 적용이 에너지 절감에 가장 큰 효과가 있는 것으로 나타났으며, 차로확장, 신호최적화, HOV 차로 운영 순으로 에너지 절감 효과가 나타났다. 본 연구는 차종에 대한 특성의 고려, 잠재수요에 대한 고려를 하지 않았으며, 분석 기간이 단지 첨두 1시간에 그쳤기 때문에 향후 이러한 현실적 요소에 대한 고려 및 시스템의 확대적용에 있어 보다 정확한 경제성 분석절차 및 방법론적 개선이 요구된다고 하겠다.

• 항공우주기술
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• 제2권2호
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• pp.151-156
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• 2003

액체 로켓엔진시스템은 연료공급방식에 따라 가압식과 터보펌프식으로 나눌 수 있으며, KSR-III 과학로켓에서는 가압식 액체 로켓엔진을 사용하였으나, 현 시점에서 우주발사체 1단으로 가압식 액체로켓엔진을 사용하기에는 극복해야할 기술적 과제가 많으며, 가압식 액체로켓 기술의 한계로 인해 터보펌프식 액체 로켓엔진 개발이 요구되고 있다. 본 연구에서는 터보펌프식 액체로켓 엔진시스템의 기본적 특성을 검토하기 위하여 국내 액체로켓 엔진의 차세대 추진제 조합으로 주목받고 있는 케로신(Kerosene)-액체산소(LOX)와 메탄(Methane)-액체산소 추진제에 대한 분석을 수행하였다. 또한 터보펌프식 액체로켓 엔진시스템의 기본적 특성을 검토하기 위해 직접 궤도 및 전이 궤도를 거쳐 위성을 투입하는 발사체 사이징 안을 각각 고려하여 분석하였다.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.20-25
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• 2012

As a kind of distributed energy system, the co-generation system based Diesel engine using after-treatment device was devised for its environmental friendly and economic qualities. It is utilized in that the electric power is produced by the generator connected to the Diesel engine, and waste heat is recovered from both the exhaust gases and the engine itself by the finned tube and shell & tube heat exchangers. An after-treatment device composed ceramic heater and DOC(Diesel Oxidation Catalyst) is installed at the engine outlet in order to completely reignite the unburned fuel from the Diesel engine. In this study, mutual relation of each experimental condition was derived through minimum number of experiment using Taguchi Design and ANOVA recently used in the various fields. It is found that the total efficiency (thermal efficiency plus electric power generation efficiency) of this system reaches maximum 94.4% which is approximately higher than that of the typical diesel engine exhaust heat recovery system.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.40-48
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• 2013

Recently, many types of electric vehicles including a heavy duty vehicle have been developed and released because of the better fuel economy and less gas products. In this study, research about an electric bus which utilizes the wheel motor drive system was conducted. The wheel motor is a motor connected to the wheel directly only with a simple gear so that the developer can utilize the space efficiently and the whole system efficiency will be better because of simple structure. However, because it is different from former types of vehicles which use the differential gear, the development of the integrated control logic is required in order to meet the vehicle stability and driving performance. The developed control logic is composed with direct yaw moment control, regenerative braking control and slip control logics. It is compared to the control logics which does not consist of direct yaw moment control and slip control when the vehicle is exposed in tough situations. For the unification of the control logic, a few maps were developed and applied to determine the output torque of each motor according to the driving status. As a result, it is shown that the developed control logic is more safe and well follow the target speed than the other control logic applied simulations.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.629-634
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• 2011

초고속 비행체에 적용 가능한 소모성 터빈엔진 개발을 위한 사전연구를 수행하였다. 엔진 요구도 및 설계점 결정을 위한 가상 운용임무형상을 선정하고, 유사급 엔진과 참고문헌 등을 통해 확보된 데이터를 활용하여 설계점 해석을 수행하였는데, 해면고도, 마하수 1.2 조건에서 터빈입구온도 3,600R에 대한 설계점 계산결과, 비추력 2599.4 ft/s, 비연료소모율 1.483 lb/($lb^*h$)이 예측되었다. 설계점 계산결과를 기준으로 두 가지 임무형상에 대한 엔진 성능해석결과, 엔진 최대 순추력을 결정하는 설계변수는 천음속 및 낮은 초음속영역에서는 터빈입구온도, 높은 초음속 영역에서는 압축기 출구온도임을 확인하였다. 이밖에도 단순, 저가, 경량의 엔진형상으로 축류형 다단압축기와 직류형 연소기, 1단 축류터빈, 고정 수축팽창 노즐이 적용된 단순터보제트엔진을 제시하였다.