• 조명전기설비학회논문지
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• 제29권6호
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• pp.8-13
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• 2015

Recently, Illumination industry of LED module has been focused to industry technology for energy conservation of nation. The LED device is excellent to power efficiency due to semiconductor light source element. And the application to the lighting circuit technology can be designed to the sensitive lighting system for human sensitivity control. In this paper, as a process for analyzing the operating temperature of standardized electronic device including LED device has analyzed about fusing character with in designed micro fuse for electronic device protection from the over current. Using the de-rating technique, which is performed to micro fuse fusing test in the range of $-30^{\circ}C{\sim}120^{\circ}C$ thermostatic chamber. To the output data in each temperature zone, it is performed to first-order linear fitting. Additionally, applying the resistance temperature coefficient and statistical data for the reliable analysis has derived to the metal element resistance of micro fuse with temperature change of the thermostatic chamber. As a research result, The changed temperature effect of thermostatic chamber was confirmed regarding fusing time change.

• 대한기계학회논문집B
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• 제25권5호
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• pp.653-659
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• 2001

This paper is concerned with the development of a new method for making and separating ice in-water and saving floated ice by installing an evaporation panel in an ice storage tank. The new method shows very good heat transfer efficiency than that of the convectional method. It is because the evaporation panel is directly contacted with water in the storage tank. The experiments were performed by varying inlet and outlet refrigerant temperatures of its evaporator. From the experimental results, the operating characteristics of in-water harvest-type ice storage system were investigated by measuring temperature and pressure at each point of the ice storage system and power required to operating compressor respect to the changes of the inlet and outlet refrigerant temperature of evaporator. It can be think that defrost frequency decreased and heavy ice created as the refrigerant temperature of evaporator outlet and defrost setting temperature is low so gotten result can effect to release efficiency. Also, consumption power, condensing heat quantity, refrigerating capacity and performance efficiency decreased as time goes by. Therefore, these results provide the basic data for system optimization, performance improvement and the possibility of application to other fields.

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1007-1013
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• 2005

In this study, a step-down piezoelectric transformer was fabricated to utilize as an adapter for charging batteries of mobile electronic appliances. The ceramic part of the transformer is $Pb[(Mn_{1/3}Sb_{2/3})_{_0.05}Zr_{0.475}Ti_{0.475}]O_3$ with mechanical quality factor of 1600, electromechanical coupling coefficient $59\%$, and piezoelectric constant $d_{33}$ 1300, which can be utilized as a piezoelectric transformer. A simply fabricated disk-typed test pattern of diameter 28 mm and thickness 2 mm was used to characterize output voltage, step-down ratio as a function of electrode area with the input remained constant, and power, efficiency as a function of input voltage, and temperature-dependent electric characteristics were evaluated. The sample APT1 showed the best properties. The highest admittance, effective electromechanical coupling coefficient and an appropriate mechanical quality factor were obtained at the sample with the input/output area ratio of 1:1.5 at the common electrode, and the condition of 20 $V_{rms}$, $50\;\Omega$ made the maximum efficiency of $95\%$. The temperature was increased by 14.7'E as the input voltage was increased for $50\;V_{rms},\;50\;\Omega$.

• 동력기계공학회지
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• 제14권5호
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• pp.76-82
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• 2010

This paper investigates the optimum operating conditions to construct total automatic control system with high energy efficiency of a newly developed seawater ice machine. The machine has an electronic expansion valve(EEV) and a variable speed rotating drum with an evaporator installed inside. The coefficient of performance(COP) was used as an index to evaluate energy efficiency of the machine. At first, the opening angle of EEV was adjusted to obtain COP of the machine at a constant speed of the drum. Then, we checked seawater ice product versus opening angles of the EEV. Finally, effect of drum's rotating speed in response to product of seawater ice and seawater ice temperature were considered.

• 동력기계공학회지
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• 제21권3호
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• pp.93-101
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• 2017

In conventional adsorption chamber, adsorbent is embedded in between heat exchanger fins by wire mesh. This method impedes heat and mass transfer efficiency. So in this study, to improve the heat transfer performance of heat exchanger, a fin-tube exchanger was coated with FAPO (Ferroaluminophosphate) zeolite adsorbent. The fin-tube heat exchanger has a fin pitch of 1.8 mm with a variation of adsorbent coating thickness of about 0.1 mm, 0.15 mm and 0.2 mm. By varying cooling water temperature and chilled water temperature respecively, heat transfer rate and overall heat transfer coefficient were investigated. As a result, the heat transfer rate and overall heat transfer coefficient increase with decreasing cooling water temperature and increasing chilled water temperature. Under the basic conditions, the heat transfer rate of heat exchanger with 0.2 mm coating thickness is 11% and 43% higher than that of 0.1 mm and 0.15 mm, respectively. The overall heat transfer coefficient is $189.1W/m^2{\cdot}^{\circ}C$, it is two times lager than that of 0.1 mm.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.66-74
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• 1998

The operating torque and tribological characteristics of a cam/tappet system of an I.C. engine have an important effect on the engine efficiency. More power is lost for higher operation torque which is affected by the friction of a cam/tappet system. In this work experimental investigation of the torque behavior of a cam/tappet system was conducted to get tribological characteristics. Specifically, the torque was measured with respect to oil temperature and camshaft speed. The torque decreased with increasing camshaft speed because of decreasing friction coefficient but was hardly affected by the oil temperature. Also, the torque was the largest near the cam nose region.

• 환경위생공학
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• 제17권3호
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• pp.7-13
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• 2002

The removal efficiency of heavy metals by chitosan complex isolated from biological industrial waste was investigated through laboratory experiments. The results of the study are as follows. The adsorption kinetics of heavy metals were reached the equilibrium adsorption in approximately 30 minutes and the removal efficiency were showed 70.7～97.4%. The effect of temperature on heavy metals adsorption by chitosan complex shows that as the temperature increased, the amount of heavy metals adsorption per unit weight of chitosan complex increased. The correlation between amount of heavy metals adsorption per unit weight of chitosan complex and temperature were obtained through the coefficient of determination($R^2$). $R^2$ values were 0.75(p<0.05), 0.99(p<0.05) and 0.98(p<0.05) in Hg, Mn, and Zn, respectively. The injected chitosan complex in which 0.1 g was adsorpted highly and the removal of heavy metals was found to have the best removal efficiency A linearized Freundlich equation was used to fit the acquired experimental data. As a result, Freundlich constants, the adsorption intensity(I/n) was 0.5564, 0.4074, 0.5244 on the Hg, Mn, Zn, respectively And the measure of adsorption(k) was 2.2144, 1.6963, 2.0792 on the Hg, Mn, Zn, respectively. So, it was concluded that adsorption of heavy metals by chitosan complex is effective.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.288-297
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• 2008

Recent research efforts on study of silicon photonics utilizing stimulated Raman scattering have largely overlooked temperature effects. In this paper, we incorporated the temperature dependences into the key parameters governing wave propagation in silicon waveguides with Raman gain and investigated how the temperature affects the solution of the coupled-mode equations. We then carried out, as one particular application example, a numerical analysis of the performance of wavelength converters based on stimulated Raman scattering at temperatures ranging from 298 K to 500 K. The analysis predicted, among other things, that the wavelength conversion efficiency could decrease by as much as 12 dB at 500 K in comparison to that at the room temperature. These results indicate that it is necessary to take a careful account of temperature effects in designing, fabricating, and operating Raman silicon photonic devices.

• Korean Chemical Engineering Research
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• 제56권3호
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• pp.430-434
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• 2018

본 연구에서는 잔류 메틸렌 클로라이드 제거를 위한 마이크로웨이브를 이용한 파클리탁셀 건조에서 유효확산계수 및 물질전달계수를 조사하였다. 모든 온도(35, 45, $55^{\circ}C$)에서 건조 초기에 많은 양의 잔류 메틸렌 클로라이드가 제거되었으며 건조 온도가 증가할수록 건조 효율은 증가하였다. 건조 온도가 증가할수록 파클리탁셀의 유효확산계수($1.299{\times}10^{-13}{\sim}2.571{\times}10^{-13}m^2/s$)와 물질전달계수($1.625{\times}10^{-11}{\sim}4.857{\times}10^{-11}m/s$)는 증가하였다. 또한 낮은 Biot 수(0.0100~0.0151)로부터 건조의 진행이 주로 파클리탁셀의 외부확산에 의해 조절됨을 알 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.29-32
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• 2017

The use of electronic devices such as mobile phones and tablet PCs has increased of late. However, the power which is supplied through wires has a limitation of the free use of devices and portability. Magnetic-resonance wireless power transfer (WPT) can achieve increased transfer distance and efficiency compared to the existing electromagnetic inductive coupling. A superconducting coil can be applied to increase the efficiency and distance of magnetic-resonance WPT. As superconducting coils have lower resistance than copper coils, they can increase the quality factor (Q-factor) and can overcome the limitations of magnetic-resonance WPT. In this study, copper coils were made from ordinary copper under the same condition as the superconducting coils for a comparison experiment. Superconducting coils use liquid nitrogen to keep the critical temperature. As there is a difference of medium between liquid nitrogen and air, liquid nitrogen was also used in the normal conductor coil to compare the experiment with under the same condition. It was confirmed that superconducting coils have a lower reflection-coefficient($S_{11}$) than the normal conductor coils.