• 한국항공우주학회지
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• 제34권10호
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• pp.61-70
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• 2006

마하 4 비행 조건에서 작동하는 고성능 램제트와 듀얼모드 스크램제트 엔진의 초음속 공기 흡입구 모델을 설계하였다. 배압, 받음각, 요각 등 비행 변수의 변화에 따른 내부 유동 특성을 파악하기 위하여 규슈대학교의 불어내기식 초음속 풍동을 이용한 실험을 수행하였다. 유동 가시화를 위하여 쉴리렌 기법, 오일 가시화 기법을 이용하였으며, 정량적 성능 분석을 위하여 표면 압력 및 전압력을 측정하였다. 실험의 결과는 전산 유체 해석과 비교하였다. 본 연구는 기본적이지만 찾기 힘든 고 마하수 초음속 공기 흡입구 유동의 실험 결과를 제시한다.

• Tribology and Lubricants
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• 제26권6호
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• pp.311-316
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• 2010

Surface texturing of micro dimple or pore-shaped pattern was prepared using a fiber laser system. Surface texturing was designed to have a square pattern with a particular pitch distance for each corresponding density of 5, 10, 20, and 30%. Thermal damages such as bulges and burrs formed during laser irradiation were observed around the dimples. Thermal damages were later removed by lapping using alumina particles of $0.3{\mu}m$ in diameter. Oscillating friction tests were performed against heat-treated high speed steels under lubricated condition. The lubricant used was SAE 5W-30 automotive engine oil. Normal contact pressure and oscillating frequency was 0.28 MPa and 20 Hz, respectively. The tests were continued for 20 minutes, and friction plots were recorded for examination. Results revealed that the coefficient of friction was lowered regardless of texturing density. Moreover, the lowest coefficient of friction was obtained for 10% density texturing. It is attributed to increased lubricity due to the introduction of surface texturing. In addition, it is concluded that the optimum texturing density and pattern must be found for the best lubricity and low friction.

• 한국분무공학회지
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• 제18권2호
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• pp.106-111
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• 2013

Adulterations fuel have been using in the vehicle in these days. Because gasoline, diesel prices are rising every day. so people find more cheap price fuel. Adulterations fuel caused a serious air pollution problems. Adulteration fuel were made from waste engine oil, waste paint. According to Government regulations permit to be used recycle fuel(adulteration fuel) only in industrial boiler. Unburned fuel pollutants are effected to human health. In this paper, the hazardous air pollutants characteristics in the diesel vehicles according to adulterations of vehicle fuels were carried out in the NEDC test mode in chassis dynamometer. It is revealed that the all of the regulation pollutants (THC, NOx, CO and PM) emission in the adulterations of vehicle fuels was increased also the green house gas, $CO_2$ was increased. In the hazardous air pollutants characteristics, the VOCs(Volitile Organic Compounds) BTEX(Benzene, Toluene, Ethylbenzene, Xylene) emissions in the adulterations of vehicle fuels showed higher level than these in the diesel fuels.

• 대한기계학회논문집B
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• 제40권2호
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• pp.103-110
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• 2016

나노유체의 대류열전달 성능을 평가하는 센서로서 가는 백금 열선이 많이 사용되었다. 그러나 센서의 강도가 약해서 취급에 주의가 필요하고 측정실험에서 센서에 대한 엄밀한 교정과정을 생략하거나 정밀도 높은 기구들을 사용하지 않으면 비현실적인 대류열전달계수가 얻어졌다. 본 연구에서는 백금 열선 대신 더미스터 센서를 채택한 새로운 나노유체 대류 성능 평가장치를 제안하였고 그 작동 원리를 자세히 설명하였다. 순수 엔진오일에 대한 두 센서의 비교 실험을 통하여 더미스터 센서의 실용적 장점을 확인할 수 있었다. 제안된 장치는 개발된 나노유체의 채택 여부를 판단하는 유용한 도구로 사용될 수 있을 것이다.

• 한국생산제조학회지
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• 제21권5호
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• pp.778-783
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• 2012

Due to the increase of oil price, the needs of the reduction of the fuel cost is rising. Therefore, necessity of hybrid vehicle that runs with engine and the electric motor is on the rise. In order to improve the performance of hybrid vehicle, many researches is carried out. Hybrid vehicles have been developed with the various layout such as serial type, parallel type, power split type, and multi-mode type. The multi-mode hybrid vehicles are designed to show the efficient driving characteristics at low speed and high speed. But the multi-mode system have the problem such as frequent clutch engagement. Frequent clutch engagement causes the shock of vehicles, and the shock inhibits the ride comfort. In this study, automation mechanism of clutch operation is proposed to mitigate the shock at engaging clutch. For this purpose, the dynamic characteristics of motor control is numerically analyzed by using Matlab/Simulink.

• 한국분무공학회지
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• 제19권1호
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• pp.40-46
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• 2014

Recently rise in oil prices feet the burden on not only diesel vehicle driver but also LPG vehicle driver, and get interested in various way to reduce fuel costs. In this study discuss on exhaust emissions characteristics on driving cycle mode and ignition advance condition change of CNG/LPLI Bi-Fuel vehicle. Experimental test was performed by changing the conditions of fuel (LPG/CNG), spark advance (Base, $10^{\circ}CA$, $15^{\circ}CA$), and driving mode (FTP-75, HWFET, and NEDC). In case of CO emission, in the order of CNG Base, CNG S/A10, S/A15 condition are average reduced -21%, -35%, -29% respectively compared to LPG fuel. The active emission reduction from the initial engine start, spark retard is likely to be beneficial in catalyst warm-up and improve combustion stability rather than spark advance.

• 한국소음진동공학회논문집
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• 제25권9호
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• pp.606-613
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• 2015

In this study, the torsional vibration analysis for a marine propulsion system is carried out by using the transfer matrix method(TMM). The torsional moment produced by gas pressure and reciprocating inertia force may yield severe torsional vibration problem in the shaft system which results in a damage of engine system. There are several ways to control the torsional vibration problem at hand, firstly natural frequencies can be changed by adjusting shaft dimensions and/or inertia quantities, secondly firing order and crank arrangement are modified to reduce excitation force, and finally lower the vibration energy by adopting torsional vibration damper. In this paper, the viscous torsional vibration damper is used for reducing the torsional vibration stresses of shaft system and it is conformed that optimum model of the viscous damper can be determined by selecting the geometric design parameters of damper and silicon oil viscosity.

• 한국화재소방학회논문지
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• 제20권3호
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• pp.96-100
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• 2006

소형선박의 기관실을 상사한 모형실에서 분말소화설비의 개발을 위한 화재시험을 수행하였다. 화재시험이 수행된 모형실은 $2.9m^3,\;4.5m^3,\;8m^3$ 3종류였으며 각 모형실에는 개구부와 송풍용 팬이 설치되었다. 경유를 소화모형의 연료로 사용하였다. 또한 소화약제 방출용 노즐은 천장에서는 하향으로 벽 또는 벽의 모서리에서는 수평으로 분사되도록 설치하였다. 개발제품은 모든 소화모형을 분말소화약제 방출 중에 소화하였으며 소화 후 재발화가 없었다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권10호
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• pp.1354-1359
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• 2014

A survey is carried out for the future energy sources to be used for ship's propulsion and ship's machinery and operations. 44 global experts from Korea, America, Norway, Denmark, Japan and German who are currently working in the shipyard and offshore fields participated at the survey. Quantitative predications on the market shares of various energy sources, such as oil, LNG, fuel cell, wind energy, solar energy and nuclear energy are made. MPI (market prediction index) is considered as a quantitative index for easy comparison between future's energy sources used for ship's propulsion and operations. It is expected that the MPI of LNG becomes twofold in 2020 against 'before 2016'. It could be also said that hydrogen based fuel cell is expected to increase rapidly for the coming years unless a new alternative energy appears.

• 한국생산제조학회지
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• 제24권3호
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• pp.294-301
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• 2015

Oil filters for vehicular parts are used under high and low temperatures as the engine is cooled, and defects can be generated with repeated changes in the operating environment and with changes in the shape, such as very high internal losses for the bolts. Visually checking for defects inside a bolt is impossible. Nondestructive evaluation methods such as eddy current testing (ECT) are recommended as a more effective way to examine inside a bolt and detect surface defects in a short amount of time. In this study, the fit bobbin coil eddy current probe was applied to checking the bolts. The bolt parameters were calculated by using a COMSOL analysis program to obtain parameters for professional interior design and fault diagnosis.