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A Study on Cooling Characteristics of the LED Lamp Heat Sink for Automobile by Forced Convection
Ho-Dong Yang(양호동),Jae-Young Yoo(유재용),Seul-Hyun Park(박설현) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.6
Automotive headlamps have been continuously developed as one of the most important devices for securing the driver’s view, and the LED lamps are getting popular in recent years. However, in case of the LED lamps, because the heat generated by the LED lamps are too high, it shorten the product life and lower the LED efficiency. Therefore, this study was investigated the cooling characteristics of the LED lamp heat sink for automobile by forced convection for LED heat generation control. In order to analyze the cooling characteristics of the heat sink, the temperature distribution results were investigated through the experiment and computational analysis under the increase of the air flow velocity, and the convective heat transfer coefficient was obtained. Also, convective heat transfer coefficient was calculated by the theoretical formula under the same condition and compared with experimental and computational results. From the result of this study, as the air flow velocity around the heat sink fins increased, the convective heat transfer coefficient significantly increased, confirming the improvement in the cooling effect.
초음파에 의한 상변화 물질의 용융촉진 과정 분석 및 가시화
양호동(Ho-Dong Yang),오율권(Yool-Kwon Oh) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.6
This study analyzed the melting process of solid-liquid phase change material (PCM) and applied the visualization to investigation of heat transfer by ultrasonic vibrations. For heating condition, we considered the constant heat flux condition and investigated the melting process of a PCM from a heated vertical wall for the following; one without ultrasonic vibrations (natural melting) and the other with ultrasonic vibrations. in the present study, heat flow was measured in the absence of and in the presnece of acoustic streaming. This streaming produced by ultrasonic vibrations was visualized by a particle image veiocimetry (PIV) and a thermal infrared camera. Ther experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times, compared to the rate of the melting without ultrasonic vibrations. Also, temperature and Nusselt numbers over time provided conclusive evidence of the important role of acoustic streaming on the melting phenomena of the PCM.
연소실험 임무수행을 위한 KMSL 큐브위성 과학 탑재체의 구조 안전성 검토에 관한 전산해석 연구
양호동 ( Ho-dong Yang ),박설현 ( Seul-hyun Park ) 조선대학교 공학기술연구원 2021 공학기술논문지 Vol.14 No.1
In this study, the structural stability of a scientific payload installed on a KMSL cubesatellite for combustion experiment mission was investigated by a computational analysis. A scientific payload was preliminary design based on the design criteria of the pressure vessel, and linear structure analysis was performed using ANSYS V19.2 to verify the stability. As a result of this study, it was indicated that most of the maximum equivalent stress and strain occured in the center of the payload optical window. However, the payload designed with a minimum MOS of 2.94 has been shown to be structurally stable and robust under the given environmental conditions. Also the payload optical window can be damaged when the pressure difference between the inside and outside of the payload is 5 atm<sub>abs</sub>.
수치해석을 이용한 Tire Mold용 Al 금형의 온도분포 해석에 관한 연구
양호동(Ho-Dong Yang),오율권(Yool-Kwon Oh),서동표(Dong-Pyo Seo),박근욱(Keun-Uk Park),김우진(Woo-jin Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The plant of Al alloy mold must be established to produce the good quality tires. But mild steel molds are used as tire mold which is consist of one piece. This type of metal mold is more economic in the total cost but the quality of product is not good. Therefore, in the present study, Al alloy mold which consist of six pieces was introduced. And, numerical work using a finite element method (FEM) was applied to analyze that Al alloy mold was happened the characteristics of temperature distributions. Also, the contraction rate occurred by temperature distributions investigated to predict the accurate measurement variations of Al alloy mold.
양호동(Ho-Dong Yang),오율권(Yool-Kwon Oh) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
In the present study investigated the heat transfer during the boiling process of a pure water when the ultrasonic waves were applied. Heat transfer coefficient and acoustic pressure distributions were measured with and without ultrasonic waves during the boiling process, respectively. The results of study, heat transfer coefficient and profiles of acoustic pressure is higher with ultrasonic waves than without one. Especially, augmentation ratio of heat transfer is more increase the convection state then sub-cooled boiling and saturated boiling states. Also, acoustic pressure is higher near ultrasonic transducer then other points where is no installed it. Finally, the augmentation of heat transfer is closely related to the acoustic pressure during applied ultrasonic waves in a medium.
양호동(Ho-Dong Yang),오율권(Yool-Kwon Oh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This study investigated the effect of pressure variations on augmentation of heat transfer when the ultrasonic waves were applied. The augmentation ratio of heat transfer was experimentally investigated and was compared with the profiles of pressure distributions calculated applying a coupled finite element-boundary element method (coupled FE-BEM). As the ultrasonic intensities increase from 70W to 340W, the velocity of the liquid paraffin is found to increase as well as kinetic energy, This physical behavior known as quasi-Eckart streaming results from acoustic pressure variations in the liquid. Especially, the higher acoustic pressure distribution near two ultrasonic transducers develops more intensive flow (quasi-Eckart streaming), destroying the flow instability. Also, the profile of acoustic pressure variation is consistent with that of augmentation of heat transfer. This mechanism is believed to increase the ratio of hear transfer coefficient.
양호동(Ho-Dong Yang),오율권(Yool-Kwon Oh) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The Present Study reported on the experimental and numerical results of heat trannsfer in the acoustic fields induced by ultrasonic waves. The strong upwards flow called as acoustic streaming was visualized by a particle image velocimetry (P.I.V). in addition, the augmentation of heat transfer was experimentally investigated in the presence of acoustic streaming and was compared with the profiles of acoustic pressure calculated by the numerical analysis. Experimental and numerical studies clearly show that acoustic pressure variations are closely related to the augmentation of heat transfer.