• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1538-1544
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• 2014

In recent years, The electronic and energy industries demand low power consumption and high efficiency, so under their demands, the white goods industries which are represented for refrigerator and air conditioner system be implemented energy-saving power suppling structure with inverter control system. As inverter control system is different from step control type, when switching system is optimizing temperature control during short period, the inrush plus current can be flown in the circuit. In despite of these characteristics, there is no fuse which can be applied to this type until now. For this reason, we suggest the method of manufacturing protector in the high efficient inverter control system using the alumina-based ceramic radiated heat characteristics and metal films laminated plating. And through the evaluating electrical characteristics, we make a possible to utilize the method when designing overall fuses.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.3
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• pp.284-290
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• 2012

Infrared thermography uses infrared energy radiated from any objects above absolute zero temperature, and the range of its application has been constantly broadened. As one of the active test techniques detecting radiant energy generated when energy is applied to an object, ultrasound infrared thermography is a method of detecting defects through hot spots occurring at a defect area when 15~100 kHz of ultrasound is excited to an object. This technique is effective in detecting a wide range affected by ultrasound and vibration in real time. Especially, it is really effective when a defect area is minute. Therefore, this study conducted thermography through lock-in signal processing when an actual defect exists inside the austenite STS304 seamless pipe, which simulates thermal fatigue cracks in a nuclear power plant pipe. With ultrasound excited, this study could detect defects on the rear of a pipe by using an aluminium reflector. Besides, by regulating the angle of the aluminium reflector, this study could detect both front and rear defects as a single infrared thermography image.

• Fire Science and Engineering
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• v.19 no.1 s.57
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• pp.46-50
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• 2005

Burning characteristics of working uniform was studied in this paper experimentally. Initial ignition point was classified in three cases that is midpoint of sleeve (Sleeve case), front side midpoint of coat (Center case) and midpoint of trousers (Leg case). The results are as follows· The remained mass ratio was decreased in order of Leg case, Sleeve case, Center case. And the highest average temperature of surface was appeared in order of Sleeve case, Center case, Leg case. Maximum radiant heat flux during burning was appeared high in order of Sleeve case $(0.5\;W/cm^2)$, Center case $(0.45\;W/cm^2)$, Leg case $(0.44\;W/cm^2)$.

• Journal of Environmental Impact Assessment
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• v.21 no.2
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• pp.239-246
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• 2012

Daily net radiation is essential for heat budget analysis for environmental impact assessment in the coastal zone and longwave radiation is an important element of net radiation because there is a significant exchange of radiant energy between the earth's surface and the atmosphere in the form of radiation at longer wavelengths. However, radiation data is not commonly available, and there has been no direct measurement for most areas where coastal environmental impact assessment is usually most needed. Often an empirical equation, e.g., Penman and FAO-24 formulae is used to estimate longwave radiation using temperature, humidity, and sunshine hour data but local calibration may be needed. In this study, local recalibration was performed to have best fit from a widely used longwave equation using the measured longwave radiation data in Korea Global Atmospheric Watch Center (KGAWC). The results shows recalibration can provided better performance AE=0.23($W/m^2$) and RMSE=14.73($W/m^2$). This study will contribute to improve the accuracy of the heat budget analysis in the coastal area.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.530-536
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• 2002

The accurate measurements of thermal expansion coefficients is one of the most important techniques required not only in material science but also in industries. A high precision interferometric dilatometer, using acoustic optical modulator, has been constructed and its performance has been tested. The system consists of a double-path optical heterodyne interferometer and a radiant heating furnace. This provides highly accurate length measurement, and allows rapid heating and cooling method for the specimen. A three longitudinal mode frequency stabilized He-Ne laser, using the secondary beat frequency, is constructed. Its stability is found to be $5{\times}10^{-9}$. The uncertainty in the length measurement is estimated to be of nanometer order in the range between room temperature to 1100 K.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.105-110
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• 2011

The objective of this study is to analyze the characteristic of radiation environment in the urban and rural through the field observation in the summer. The radiation balance was compared through the measurement of the shortwave radiation and long-wave radiation in the urban, sub-urban, and rural. The following conclusion could be obtained from this research. (1) In the results of observation including the rain-day, it was found that the short wave radiance in the urban is lower about 10% than the rural. (2) The upper part of atmosphere layers in the urban area absorb much short wave radiation energies compared with the rural relatively. It can increase the temperature of the upper part of atmosphere layers and the emittance of long wave radiation. (3) The ratio of the downward short wave radiation to the downward long wave radiation was 1.24 for the urban, 1.28 for sub-urban and1.35 for rural. It can be estimated that the atmosphere condition of the rural is better than that of other areas.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.148-154
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• 2009

By the skyscraper building, increase of skin area and expansion of curtain wall system will be the important factors of acceleration in extending supply of BIPV system. In the future interior environmental evaluation is not a necessary to the residents but an essential term which will bring enormous influence. In the interior environmental evaluation, natural light will let the residents with direct contact with outside circumstances and make them feel opened. also only the daylight has radiant energy and color rendering that will have a great influence to residents' mental, operation efficiency and advancing productivity. This research compares and analyzes BIPC system in office spaces with two general sunlight's module. In addition to natural light's efficiency for BIPC system's comfort and confirmed economical efficiency will be applied to basic research data. Hence forth, ensuring indoor intensity of illumination and controlling light system to reducing energy research data will be demanded to increase the amount of supplying BIPC system. Also continuance research in the possibility of applying BIPC system in various buildings, room temperature affected by location of windows and its condensation, and economical evaluation will be required.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.893-898
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• 2014

Recently, the interior permanent synchronous motor (IPMSM) has been applied to an integrated starter and generator (ISG) for hybrid electric vehicles. In the design of such a motor, thermal analysis is necessary to maximize the power density because the loss is proportional to the power of a motor. Therefore, a cooling device as a heat sink is required internally. Generally, a cooling system designed with a water jacket structure is widely used for electric motors because it has advantages of simple structure and cooling effectiveness. An effective approach to analyze an electric machine with a water jacket is a thermal equivalent network. This network is composed of thermal resistance, a heat source, and thermal capacitance that consider the conduction, convection, and radiation. In particular, modeling of the cooling channel in a network is challenging owing to the flow of the coolant. In this paper, temperature prediction using a thermal equivalent network is performed in an ISG that has a water cooled system. Then, an experiment is conducted to verify the thermal equivalent network.

• KIEAE Journal
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• v.7 no.6
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• pp.17-22
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• 2007

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This paper compares the experimental performance of two different types of air type PV/T collector units: the base case of a collector unit with 10cm gap for forced ventilation and the other unit with copper pin attached to PV module to enhance its thermal performance. The experimental results shows that the base case unit had the overall efficiency of 41.9% and the improved unit with copper pin attached to PV module had 50.1% efficiency. For these air type PV/T units, the forced ventilation of the air space improved the electrical performance as well as the thermal performance.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.37-41
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• 2018

$Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was prepared by floating zone method. single crystal was confirmed to have a Ia-3d (230) space group of cubic structure and showed regular morphology. The optical properties, single crystal exhibited a emission band from green, yellow wide wavelength and 610nm, 640nm red wavelength vicinity. The luminance maintenance rate was decreased by phonon with increasing temperature, but high luminance is maintained more than powder phosphor. In addition, $Y_3A_{l5}O_{12}:Ce^{3+},Pr^{3+}$ single crystal phosphor was applied to a high power blue laser diode, we implemented high power white laser lightings. and it was confirmed that thermal properties over time, due to the effective heat transfer of complete crystal structure. We confirmed that excellent radiant heat properties than powder phosphor was applied to a high power white laser diode.