• 한국정밀공학회지
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• 제24권3호
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• pp.100-107
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• 2007

A internal lobe pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. In particular, the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of internal lobe pump whose the main components are the rotors: usually the outer one is characterized by lobes with circular shape, while the inner rotor profile is determined as conjugate to the other. The topic of this paper is the design of a new rotor, which is based on specific performance as different types depending on the shape of the lobe of the outer rotor. First, the design of internal lobe pumps with circular, elliptical, and their combined lobe profiles is considered. The latter is a new type of lobe profile with special shape whose curvature follows a definite function. Then we introduce the performance indexes used for the comparison. Some of these indexes, such as flow rate and flow rate irregularity, are commonly used for the comparison, while specific slipping is particularly suitable in this case. It is possible to notice that the circular and elliptical type is comparable to the circular one or the elliptical one in terms of flow rate irregularity, but has improved performance in terms of specific slipping. Results obtained from the analysis enable the designer and manufacturer of oil pump to be more efficient in this field.

• 에너지공학
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• 제22권4호
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• pp.338-346
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• 2013

일반 납축전지는 차량의 시동 성능 위주로 최적 설계되어 있다. 최근 차량 전장 시스템과 납축전지를 활용한 연비기술 적용의 증가로 납축전지의 사용 빈도가 늘어나고 있다. 연비기술 적용은 납축전지의 잦은 충방전 반응을 일으켜 납축전지 내구 수명을 단축시키고 있다. 본 연구에서는 납축전지의 노화 수명 모델 구현을 통해 배터리 내구 수명을 예측하는 방법을 제시하고자 한다. 납축전지의 노화에 영향을 미치는 요인은 방전율, 충전 시간, 완충 시간, 온도 조건 등이 있다. 본 논문에서는 납축전지의 동적 거동을 예측하기 위하여 전기화학반응 속도론, 이온의 전달현상, 전극 공극률의 시간에 따른 변화를 고려하였다. 수명 예측을 위해서 노화 메커니즘 중 노화에 가장 큰 영향을 주는 극판 부식 현상과 활물질 탈락을 노화 모델링에 반영하였다. 개발된 납축전지의 노화 모델을 검증하기 위하여 납축전지의 가속 충방전 시험을 수행하였다.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.121-129
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• 2011

Hydrocarbons which are the main sources of VOCs from motor vehicles are emitted not only from the engine exhaust gas but also from evaporation of the fuel in storage and supplying systems. Evaporative emissions from gasoline fuel systems could be classified by diurnal, hotsoak and running loss. Diurnal loss test procedures are different as countries. Korea introduced new evaporative regulation in 2009 with 24hour VT-shed test procedure and relaxed emission standards. The estimations on different test procedures in this study show that the new Korean regulation get a little more severe than before and the 2 day diurnal loss test of U.S. is the most severe. So the test procedures as well as the stronger standards should be considered in the next evaporative emission regulation to reduce VOCs from motor vehicles. The important parameters to affect evaporative emissions are air and fuel temperature and fuel vapor pressure. Diurnal loss increases exponentially as rising air temperature and vapor pressure. The effects of vapor pressure on running loss are different as the capacities of canisters. Tests with simulating real temperature and driving conditions show that hydrocarbons in evaporative emissions could be more than those in exhaust gas in summer season because of the higher air temperature.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.67-73
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• 2009

Recently, Europe decided to start the regulation of diesel engine nanoparticles because of its well known adverse health effects. The diesel nanoparticles can be classified as solid carbon particles and volatile particles. The volatile particles generates during dilution process by condensation of gas phase volatile compounds such as hydrocarbon. The new nanoparticle regulation considers only solid particles because of difficulty of measurement of volatile particles. The aim of this study is to suggest a proper dilution method that prevent the volatile particle generation. As a result, it is found that the $1^{st}$ dilution air temperature should be above $120^{\circ}C$ in order to prevent volatile particle generation effectively. It is also found that the volatile particles can be removed effectively in the evaporation tube by the increase of evaporation tube temperature. But when exhaust gas is hot enough (>$190^{\circ}C$, in this study) and it is diluted in the first diluter with high temperature air (>$120^{\circ}C$), removal phenomenon of volatile particles by increasing of evaporation tube temperature can not be seen. It means that there are no volatile particles in the diluted exhaust gas. Additionally, dilution ratio is not an important factor for volatile particle generation compared with dilution air temperature or evaporation tube temperature.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.17-22
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• 2007

GTL(Gas-to-Liquids) fuel technology was converted from the natural gas, coal and biomass into the diesel or kerosene by Fisher-Tropsch synthesis. GTL fuel have very good merits on high cetane number, low density, free sulfur, lower aromatics contents and no poly-aromatic hydrocarbons as well as the autoignition characteristics. These physical properties make it valuable as a diesel fuel with lower emissions than the conventional diesel fuel. Furthermore, GTL fuel can be use not to the engine any modification. Therefore, to evaluate emissions of GTL fuel, the tested diesel vehicles were fueled on blends of GTL fuel/ultra low sulfur diesel fuel(ULSD). And then, we found out that GTL fuel reduced regulated emissions(CO, NOx, HC, PM) compare with conventional diesel fuel.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.323-332
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• 2005

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.

• 오토저널
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• 제18권6호
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• pp.23-32
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• 1996

차량에서 엔진은 가장 큰 질량 집중체(concentrated mass)이다. 만약 엔진이 적절하게 구속되지 않거나 절연되어 있지 않으면, 차체에 진동을 일으키는 원인이 된다. 엔진은 다양한 진동 교란을 받는데 엔진 마운트는 이러한 모든 것들을 고립시키는 역할을 해야 하며, 엔진은 정적인 장착 하중에 대한 지지와 전후, 좌우 및 수직 방향의 운동에 대해 적절한 강성을 가져야 한다. 또한 정숙성을 향상시키기 위해서는 엔진 마운트의 재료인 고무의 강성계수를 낮추는 것이 필요한데 이는 일반적으로 내구성의 저하를 가져온다. 따라서 개발과정에서 강성계수를 낮추는 변경을 하면 부품의 내구성을 보정함에 따르는 재평가 또한 필요하게 된다. 엔진 마운트에 쓰이는 고무부품의 해석은 엔진 마운트 시스템에 대한 진동 해석 및 내구수명의 예측과 병행해야 하며, 진동해석으로부터 얻은 하중 지지 능력 등의 모든 요구 특성을 만족하기 위해서는 고무 재료의 특성에 대한 지식, 엔진 마운트의 장착 위치에 대한 결정 능력과 함께 주어진 조건에 대한 형상의 최적 설계 능력 등이 요구된다. 본 연구에서는 기본적인 형상을 파라미터화하여 엔진 마운트의 형상을 최적화 하는 절차를 제안하였다. 현재 승용차에 널리 사용되고 있는 부시형(bush type) 엔진마운트를 적용 모델로 선택하였으며, 엔진 마운트의 기본적인 형상을 몇개의 파라미터를 사용하여 정의하고 설계 사양으로 주어지는 강성값과 각 파라미터들의 조합으로 구성되는 형상이 갖는 강성값의 차이가 최소가 되도록 파라미터 값들을 최적화하였다. 최적화된 파라미터 값들로 구성되는 형상을 내구 성능, 성형성등을 고려하여 최종 형상으로 결정한다. 내구성능의 예측은 금속부품의 내구수명 예측에 널리 이용되고 있는 방법이 방진 고무부품의 경우에도 적용 가능한지를 검토하고, 방진 고무부품에도 일반적으로 적용될수 있는 내구수명 예측방안의 개발 가능성을 타진해 보았다. 본 연구의 목표는 시제품을 제작하기 이전에 설계된 부품에 대한 스프링 상수 및 내구특성을 체계적으로 규명하여 제품 시험의 횟수를 줄이고, 보다 정밀한 제품을 제작할 수 있도록 하기 위한 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.133-138
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• 2005

Automotive pulleys play a key role in driving the cooling pump, oil pump, air-conditioner and so on by using an engine power. Researches on design processes and technologies of the pulleys can be found in many literatures. On the other hand, the areas related to manufacturing processes of the pulleys have been treated negligently. Vast data extracted from various information systems are transformed, integrated, and summarized to become a special database for helping users make a decision. The database, namely the data warehouse has been popularly used in the marketing and customer management of enterprises and recently applied to improve the design and manufacturing processes. In this study the manufacturing process of pulleys were analyzed through the intensive investigation of shop-floors and the interviews with workers and managers. The defects generated during a manufacturing process were categorized in a few types and the causes of defects examined for extracting the dominant parameters in the setup process for producing pulleys. As the first step to construct the data warehouse for the manufacturing processes of pulleys, authors proposed its architecture focused on the reduction of defect rate during the setup process.

• Journal of Welding and Joining
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• 제34권1호
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• pp.26-34
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• 2016

Automotive today has been transforming to an electronic product by adopting a lot of convenience and safety features, suggesting that joining materials and their mechanical reliabilities are getting more important. In this study, a Sn-Cu-Cr-Ca solder composition having a high melting temperature ($>230^{\circ}C$) was fabricated and its joint properties and reliability was investigated with an aim to evaluate the suitability as a joining material for electronics of engine room. Furthermore, mechanical properties change under complex environment were compared with several existing solder compositions. As a result of contact angle measurement, favorable spreadability of 84% was shown and the average shear strength manufactured with corresponding composition solder paste was $1.9kg/mm^2$. Also, thermo-mechanical reliability by thermal shock and vibration test was compared with that of the representative high temperature solder materials such as Sn-3.5Ag, Sn-0.7Cu, and Sn-5.0Sb. In order to fabricate the test module, solder balls were made in joints with ENIG-finished BGA and then the BGA chip was reflowed on the OPS-finished PCB pattern. During the environmental tests, resistance change was continuously monitored and the joint strength was examined after tests. Sn-3.5Ag alloy exhibited the biggest degradation rate in resistance and shear stress and Sn-0.7Cu resulted in a relatively stable reliability against thermo-mechanical stress coming from thermal shock and vibration.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.118-124
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• 2007

The efficiency of the hybrid systems which are composed of compound planetary gear sets depend on the amount of the recirculating energy among the motors and battery. This paper studies the analysis of the system efficiency with the parameters, ${\alpha},\;{\beta},\;{\gamma_a},\;{\gamma_b}$ and $\gamma_s$. The efficiency of the systems and the relative torque, speed and power of the power resources are represented by these parameters. The recuperating parameter $\kappa$ which makes the systems generalized is introduced, so the efficiencies of the modes such as the hybrid mode, the engine mode, the motoring mode and the recuperating mode are analyzed with simple equations. The tendency of the system efficiency according to the variations of the $\gamma_s$ and $\kappa$ are studied, by which it can be possible to reduce the loss of the power because the strategies for avoiding the singular speed ratio $\gamma_s$ are helpful for the system efficiency and specific value of $\kappa$ can increase the efficiency of the systems.