• 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.

• Journal of Soil and Groundwater Environment
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• v.20 no.1
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• pp.36-40
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• 2015

This study examined the disinfection in combined sewer overflows (CSOs) by pulsed ultraviolet (PUV). The reflectors (stainless steel. mirror, aluminium foil, aluminium (1050), aluminium (6061), aluminium (5052), and aluminium mirror) of PUV irradiation was performed in a 90 L stainless reactor at a constant temperature of $20^{\circ}C$ and an applied power of 4000 W. The reflection efficiency of reflectors were showed 1.00 (aluminium mirror) ~ 1.48 (aluminium foil) does. The case of a rough surface analysis using SEM showed high reflectance, was the case of a smooth surface and a low reflectivity. Pseudo first-order rate constant calculated results, has a higher reflectivity values were more than twice as high compared to the low reflectivity. Affected Total coliforms disinfection time, depending on the type of reflector is considered.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.377-382
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• 2000

Film bulk acoustic resonator (FBAR) using AIN reactively sputtered at room temperature was fabricated. The FBAR is composed of a piezoelectric aluminium nitride thin film, top electrode of Al and bottom electrode of Au connected by a short (200${\mu}{\textrm}{m}$) transmission line on both sides and reflector layers of SiO$_2$- W Pair. The active areas of Al and Au were patterned using 150${\mu}{\textrm}{m}$ diameter shadow mask. The series resonance frequency (fs) and the parallel resonance frequency (fp) were measured at 1.976 GHz and 2.005 GHz, respectively. The minimum insertion loss and return loss were 6.1 dB and 37.19 dB, and the quality factor (Q) was 4261.

• New & Renewable Energy
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• v.4 no.4
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• pp.17-22
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• 2008

A low concentrating (< 5X) photovoltaic module with aluminum reflectors is fabricated and evaluated which is designed to reduce the affection of the high temperature to the solar cell modules preventing the efficiency lowering. As results, the output power is increased of 1.97X from the concentrating photovoltaic module which is designed with the concentrating ratio of 2.25X and to control the module temperature cooling the module by air circulation. Also, the effect of the concentrating module with aluminum reflectors on the conventional PV module is investigated at the field. The result shows the increase of the output power more than about 20% and the improvement of the module efficiency of 1.4X in spite of the increase of average module temperature.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.114-117
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• 2008

본 연구에서는 알루미늄 반사판을 이용한 저집속 (2.25X) 집광형 태양광 모듈을 설계 및 제작하여 실증 연구를 실시하였다. 반사판을 이용한 집광형PV시스템의 성능향상을 평가하기 위하여, 일사량과 모듈온도 변화에 따른 출력변화와 효율변화를 평판형 모듈과 집광형 모듈에 대해서 각각 측정하고 비교하였다. 결과적으로 반사판을 사용 집속한 모듈이 약 20% 이상의 출력 증가를 보였으며, 모듈의 평균 온도 상승에도 불구하고 1.4 배의 발전효율 증가를 확인하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.118-120
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• 2008

고집속에 따른 태양전지 온도상승에 의한 태양전지 효율 저하를 방지하고,경제적인 저집속형(<5X) 집광형 태양광 모듈 개발을 위하여 본 연구에서는 알루미늄 반사판을 이용한 저집속 (< 5X)집광형 태양광 모듈을 설계 및 제작하여 성능 평가를 실시하였다. 2.25X의 집속비와, 태양광 집속에 의한 태양전지 모듈의 온도 상승을 공기순환을 통한 냉각이 가능하도록 설계/제작된 집광형 태양광 모듈로 부터 1.97배의 출력 증가를 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.141-149
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• 1998

Diamond shaping is one of the machining strategies to make the optical micro-groove molds, and it is especially useful when the component is an assembly of the linear micro-groove array. A mirrorlike surface and an arbitrary crose-sectional curve can be easily made by the diamond tool. However, the cutting speed of shaping is relatively lower than that of the other cutting methods, and there exist an unstable cutting conditions that generate the chatter. This study is focused on the modeling of the simplified self-induced chatter of the diamond shaping, and the machinabilities of three materials are compared by cutting experiments. From the chatter model and experiments, it is found that the unstable cutting conditions exist when the depth of cut is low and cutting speed is high. It is also found that the brass is relatively good material in micro shaping than copper or aluminium from the cutting experiments.

• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.80-86
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• 2013

In this study, the photocatalytic reactor system equipped with photocatalyst-carrying-silica-media cartridges [photocatalytic reactor system (1)] was used to perform the treatment of waste air containing malodor and volatile organic compound (VOC). The result of its performance was evaluated and compared with that of the photocatalytic reactor system equipped with commercial photocatalyst-carrying-nonwoven filter-media cartridges [photocatalytic reactor system (2)]. In case of photocatalytic reactor system (1), at the 1st stage of run the removal efficiencies of ethanol and toluene continued to be 80% and 20%, respectively. However, unlike toluene, the removal efficiency of ethanol dropped to 40% at the end of the 1st stage of run. The removal efficiency of hydrogen sulfide decreased from 100% to 90%. At the 2nd stage of its run the removal efficiency of ethanol decreased to 10% while the removal efficiencies of hydrogen sulfide and toluene remained as same as 90% and 20%, respectively, even though the inlet load of toluene increased by factor of four. In the 3rd stage of its run, as the result of application of aluminium-coated reflector film to the inner wall of photocatalytic reactor system, the removal efficiencies of ethanol and toluene increased by 5% to be 15% and 25%, respectively. In case of photocatalytic reactor system (2), at the 1st stage of its run, the removal efficiencies of ethanol, hydrogen sulfide and toluene continued to be 10%, 97% and 100%, respectively. However, at 2nd stage of its run their removal efficiencies became 5%, 95% and 2~3%, respectively, which showed that the removal efficiencies of ethanol and hydrogen sulfide decreased insignificantly while the removal efficiency of toluene dropped significantly from the perfect elimination. Moreover, the reflector film did not affect the performance of photocatalytic reactor system (2) at all. Therefore the removal of ethanol, hydrogen sulfide and toluene by photocatalytic reactor system (2) was mainly attributed to hydrophobic adsorption of its nonwoven filter media and its extent of photocatalytic removal turned out to be negligible, compared to that of photocatalytic reactor system (1).