• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1345-1348
• /
• 2005

We designed the compound CVT (Continuously Variable Transmissions) by combining power circulation mode CVT and power split mode CVT, which have been proposed for connecting 2K-H I differential gear to the V- belt type CVU (Continuously Variable Unit), as an input coupled type. With the designed compound CVT, we carried out theoretical analysis and performance experiments. We proved that the compound CVT had a better performance than either of the power circulation mode or power split mode.

• 동력기계공학회지
• /
• 제15권4호
• /
• pp.42-47
• /
• 2011

The purpose of this study is to investigate the best melting condition with various winding number of a heating pipe, supplying quantity of engine coolant and coolant temperature at the inlet of the heating pipe. Also, it is to suggest getting method of an appropriate quantity of the agent for the urea-SCR system within 10 minutes. For this matter, this study identifies the temperature distribution of inside of urea-tank while it is frozen at the low temperature condition, and suggests the best melting condition of the frozen urea within 10 minutes. From the results, it was found that 2L of melted urea was obtained by the coolant flow rate of 200L/hr at $70^{\circ}C$ for 10 minutes from the start of engine operating.

• 한국정밀공학회지
• /
• 제21권4호
• /
• pp.170-178
• /
• 2004

Continuously variable transmission (CVT) mechanisms considered here are input coupled types that combine the functions of a 2K-H II type differential gear and a V-belt type continuously variable unit (CVU). For the 8 different mechanisms, 4 of them are power-circulation modes while the other 4 are power-split modes, various performance analysis (speed ratios, power flows, divisions of power transmission in a differential gear and a CVU, and theoretical efficiencies) are performed to vary design parameters. Experimental studies are executed to validate fundamental relations (speed ratios, power flows, efficiencies, occurrence of geared neutral). Some useful characteristics associated with performance also are discussed in the mechanisms.

• 동력기계공학회지
• /
• 제12권5호
• /
• pp.20-26
• /
• 2008

양산되는 승용차용 토크 컨버터 내부의 유동을 LDV 측정 기술을 이용하여 정량화했다. 속도비 0.4와 0.8 경우에 대한 속도 측정을 통해 임펠러 유로 중간과 출구 영역의 질량 유동율 특성을 분석했다. 측정 단면의 속도 분포는 유로의 위치와 속도비에 따라 많은 차이를 보이며, 특히 속도비 0.8 조건에서 임펠러 유로 중간영역 흡입면 부근의 유동은 유동박리에 의한 재순환 현상을 나타내며, 이와는 대조적으로 출구 영역에서는 흡입면을 따라 역류 현상이 발생한다. 임펠러 유로 내부의 유동은 각 영역에서 속도비에 따라 개별적 유동 특성을 보인다. 질량 유동율은 모든 속도비와 측정단면에서 주기적인 변화를 보이며, 또한 터빈의 순간적인 위치가 임펠러 유로 측정단면의 질랑 유동율에 매우 큰 영향을 미치는 것이 밝혀졌다 따라서 토크 컨버터 임펠러의 유로 방향 유동 특성 변화는 컨버터 설계에 중요하게 고려되어야 할 것으로 보인다.

• 동력기계공학회지
• /
• 제6권2호
• /
• pp.12-17
• /
• 2002

Recently, the world is faced with very serious problems related to the air pollution due to the exhaust emissions of the diesel engine. So, many of researchers have studied to reduce the exhaust emissions of diesel engine. This study was investigated for various exhaust emissions according to operating conditions in a turbocharged D.I. diesel engine. As a result of experiments in a test engine, the $CO_2\;and\;NO_x$ increased with increasing load, the $CO_2$ and CO decreased with increasing charge air pressure in manifold, the CO decreased with increasing cooling fresh water temperature, and the $NO_x$ decreased with worming cooling fresh water before engine start.

• 동력기계공학회지
• /
• 제5권1호
• /
• pp.50-56
• /
• 2001

Jet pumps are used in a great number of engineering applications. In the present study, jet shapes, mixing chamber shapes, and numerical methods for predicting the performance of an annular-type jet pump are investigated to determine the optimal turbulence model. The flow fields are simulated by solving the momentum and the continuity equations with the standard ${\kappa}-{\epsilon}$ and the RNG ${\kappa}-{\epsilon}$ turbulence models at different Reynolds numbers. After that, they are compared with the corresponding experimental data to determine the optimal model. Next, various calculations are conducted to find an optimal shape using the selected turbulence model. The study shows us that the RNG ${\kappa}-{\epsilon}$ model predicts the performance more exactly, and also shows that the most effective performance can be achieved with $12^{\circ}$ reducing angle and 130mm throat length.

• 동력기계공학회지
• /
• 제3권3호
• /
• pp.29-35
• /
• 1999

The purpose of study is to investigate the flame stability and structure of turbulent diffusion flame behind the hollowed flame holder, which is located on the waste gas coming out from the test furnace. PDFs and Power Spectra technique of fluctuating temperature and ion current measurement were needed for this purpose. We discussed that the three types of stabilized flames were found as the result of post study. In this paper, we established the stability mechanism near the flame holder.

• 동력기계공학회지
• /
• 제11권4호
• /
• pp.12-17
• /
• 2007

Recently, many small and medium size diesel vehicles have been equipped with turbocharger and EGR system to get high performance and reduce $NO_x$ emissions but its application to heavy-duty diesel engine is not common yet. In this work, the simulation model for EURO-3 engine was developed using WAVE and then its performance and emission level were verified by comparing with experimental results. The possibility of current EURO-3 engine equipped with LPL EGR system which would be satisfied the EURO-5 regulation are examined. ESC 13 mode was chosen as the primary engine test mode, and the injection timing and fuel quantity were changed to compensate the lost engine performance caused by EGR. The system developed in this study shows that the current EURO-3 engine could satisfy EURO-5 $NO_x$ regulation by applying LPL EGR.

• 동력기계공학회지
• /
• 제8권1호
• /
• pp.18-23
• /
• 2004

The direct injection diesel engine is one of the most efficient thermal engines. For this reason DI diesel engines are widely used for heavy-duty applications. But the world is faced with very serious problems related to the air pollution due to the exhaust emissions of diesel engine. So, that is air pollution related to exhaust gas resulted from explosive combustion should be improved. Exhaust Gas Recirculation(EGR) is a proven method to reduce NOx emissions. In this study, the experiments-were performed at various engine loads while the EGR rates were set from 0% to 20%. The emissions trade-off and combustion of diesel engine are investigated. Hot and cooled EGR are achieved without cooling and with cooling respectively. It was found that the exhaust emissions with the EGR system resulted in a very large reduction in oxides of nitrogen at the expense of higher smoke emissions. Also, the reduction rates of NOx emissions for hot and cooled EGR are similar at load 20%.

• 동력기계공학회지
• /
• 제14권5호
• /
• pp.56-62
• /
• 2010

In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.