• Korean Journal of Materials Research
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• v.8 no.1
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• pp.64-70
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• 1998

자동차의 엔진밸브 스프링으로 사용되는 Si-Cr 스프링강의 영구 변형 저항성과 내피로성이 우수한 고강도강을 개발하기 위하여 탄소함량을 증대시키고 Mo, V, W와 같은 합금원소를 기존의 SAE 9254 스프링강에 첨가하여 개발강을 제조했다. SEM및 EDX가 부착된 TEM을 이용하여 미세조직을 관찰했고, 크립시험 및 피로시험기를 이용하여 스프림의 영구 변형 저항성 및 스프링의 내피로성을 조사했다. 실험결과, 개발강은 피로 특성치는 기존강과 동등 수준이면서 인장강도가 기존강의 것보다 10%가 더높은 2100MPa 급의 고강도를 나타내었으며 또한 영구 변형 저항성도 현저하게 개선되었는데 이는 W, Mo의 첨가로 인해 템퍼링시에 세멘타이트의 성장이 억제되어서 세멘타이트의 석출물이 미세하게 되었기 때문이다.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.3
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• pp.111-119
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• 1997

In this study, feasibility of expansion of BFL equivalence ratio are examined with change of injection location of hydrogen gas in intake pipe, coolant temperature, spark timing and amount of residual gas. As the results, BFL equivalence ratio is increased when injection location has some distance from intake valve. And it is decreased in accordance with increasing of coolant temperature and advance of spark timing. The amount of residual gas has little effect on BFL equivalence ratio.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.938-946
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• 2008

Fe-base amorphous alloy and two crystalline phases composite were fabricated. The effect of temperature and strain rate on mechanical properties was evaluated utilizing compression test. Mixture of non-crystalline and crystalline phases were found using X-ray diffraction (XRD) and differential thermal analysis (DTA) tests. Based on glass transition temperature and crystallization temperature. compression tests were performed in the temperature ranging from $560^{\circ}C$ to $700^{\circ}C$ with $20^{\circ}C$ interval. Relationship between microstructure, including fracture surface morphology, and mechanical behavior was studied. The peak stress of Fe-base amorphous alloy was over 2GPa and expected to have a good wear resistance, but it is expected hard to deform because of low ductility. The peak stress and elongation of two crystalline phases composite was over 1GPa and about 20%, therefore it is possible to deform high strength wear resistant materials such as engine valve.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.393-400
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• 2000

In this paper, a new algorithm for noninteracting control system design is proposed and applied to ship propulsion system control. For example, if a ship diesel engine is operated by consolidated control with controllable pitch propeller (CPP), the minimum fuel consumption is achieved satisfying the demanded ship speed. For this, it is necessary that the ship is operated on the ideal operating line which satisfies the minimum fuel consumption, and the both pitch angle of CPP and throttle valve angle are controlled simultaneously. In this context of view, this paper gives a controller design method for a ship propulsion system with CPP based on noninteracting control theory. Where, linear matrix inequality (LMI) approach is introduced for the control system design to satisfy the given $H_{\infty}$, constraint in the presence of physical parameter perturbation and disturbance input. To the end, the validity and applicability of this approach are illustrated by the simulation in the all operating ranges.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.447-452
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• 2009

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchanger with R410A. This study carried out experimental and numerical analysis for indoor heat exchangers. In the experimental study, capacity of the indoor unit was estimated 8.3 kWh with the valve opening rate of 95% for the 50% partial operation condition. The air temperatures were measured using 80 thermocouples. This study also compared experimental data with the calculated data for the outlet temperature and the tube length. It is found that the relative errors between the experiment data and the calculated result are 4.2% and 0.5% for the outlet temperature and the tube length, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.692-696
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• 2011

A clutch is a very important component when engine starts and gear shifting is needed. The clutch the most commonly used is the dry clutch. This type of clutch has pads, and they are worn after disengagement of clutch little by little. The characteristics of the clutch changes as these pads wear, so wear needs to be measured, and the clutch should be controlled for proper operation. In this study, the clutch contact point estimation algorithm has been developed. From this algorithm, clutch force map changes depending on wear, and the clutch operates properly. We also see the shifting transient of a vehicle for drivability with throttle valve position control and synchronizer movement.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.226-231
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• 2006

The fuel injector is a pa.1 that controls the fuel supply of automotive engine. The housing of the fuel injector supports the rod, the needle valve and the solenoid. In this study, the rigid-plastic FE-analysis by using the design of experiments (DOE) and the response surface methodology (RSM) has been performed to produce the product reducing the under-fill and the maximum effective strain. From the results of DOE, the stem of counter punch and the face angle of punch at the $1^{st}$ process, and the stem of punch at the $2^{nd}$ process were determined as the significant design variables far each response such as the upper under-fill, lower under-fill and the maximum effective strain. From the results of RSM, the optimal values of the design variables have been also determined by simultaneously considering the responses.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.10 s.253
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• pp.1019-1025
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• 2006

Numerical simulations were conducted on the gerotor type oil pump. Three oil pump models having different port and groove shape were considered. Firstly, two original models (baseline & variant.1 model) were simulated in order to validate the accuracy of the simulation results and to better understand the flow characteristics in the pump. It was found that the cavitation phenomenon as well as the teeth tip leakage is most important parameter on the pump performance. Based on the simulation results of the original models, final model (variant.2 model) which has improved port shape and pressure relief valve is suggested to enhance pump performance and to reduce driving torque. The volumetric efficiency and the hydraulic torque of the Variant.2 model is improved 4% and reduced 6.1% each at 2000RPM in experiment.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.2
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• pp.105-111
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• 1993

내연기관의 혼합 가스 생성 장치로 흡입되는 공기의 유량을 조절하기 위해 Butterfly 밸브가 사용 된다. 이 밸브는 유량의 제어에는 매우 유용한 반면, 밸브 후면에서의 복잡한 공기의 유동현상[6] 으로 인하여 혼합가스의 생성에 장해적인 요소를 제공하기도 한다. 특히 밸브가 많이 닫힌 상태 에서는 밸브와 관로벽 사이의 간격이 좁아지는 Throttling 현상으로 인하여, 엔진에 고 부하시 흡 입되는 공기의 양이 증가하게 되어, 밸브 주위에서 공기 속도의 급증으로 인하여 유동장의 압축 성 현상을 기대할 수 있다. Throttle의 Choking 현상으로 인하여 공기의 입자는 운동에너지를 잃 게 되고, 궁극적 혼합가스의 생성에 영향을 미쳐 엔진성능의 저하를 초래하게 된다. 본 연구에서 는 실제 엔진(Central Fuel Injection Engine, 5 liters) [1]의 흡인 manifold를 modelling하여, 특히 밸브가 많이 닫힌 상태에서, 밸브 주위에서의 난류 유동의 압축성 현상을 정량적으로 분석해 보았다.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.117-126
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• 2009

A Common-Rail Direct Injection(CRDI) system for high speed diesel engines was developed to meet reductions of noise and vibration, and emission regulations. In this study, CRDI system analysis model which includes fuel and mechanical sub-systems was developed using commercial software, AMESim in order to predict characteristics for various fuel injection components. Each component which constructs system was modeled and verified by sub-model of AMESim obtained characteristics curves of each components. The parameter sensitivity analysis such as throttle size, injection rate, plunger displacement, supply pressure of fuel injection for system design were carried out by the analysis.