• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.151-152
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• 2000

For excimer laser crystallization (ELC), energy density, number of pulses, beam uniformity, and condition of initial amorphous Si (a-Si) films are significant factors contributing the final microstructure and the performance of low-temperature polycrystalline Si TFTs. The process and equipment have been achieved a significant improvement, but still, environmental factors associated with initial amorphous Si (a-Si) films and process conditions need to be optimized.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1388-1390
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• 1994

A polyimide-based capacitive humidity sensor has been designed and fabricated using silicon integrated-circuit technology, and its performance measured. The sensor showed excellent linearity, low temperature coefficient, and low hysteresis over a wide range of relative humidity and temperature. The signal conditioning circuits for detecting relative humidity and converting it to voltage have been developed based on a charge redistribution between capacitors using switched -capacitors.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.21-21
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• 2003

To increase the light-emission efficiency of LED, we increased the internal and external quantum efficiency by suppressing the defect formation in the quantum well and by increasing the light extraction efficiency in LED, respectively. First, the internal quantum efficiency was improved by investigating the effect of a low temperature (LT) grown p-GaN layer on the In$\sub$0.25/GaN/GaN MQW in green LED. The properties of p-GaN was optimized at a low growth temperature of 900oC. A green LED using the optimized LT p-type GaN clearly showed the elimination of blue-shift which is originated by the MQW damage due to the high temperature growth process. This result was attributed to the suppression of indium inter-diffusion in MQW layer as evidenced by XRD and HR-TEM analysis. Secondly, we improved the light-extraction efficiency of LED. In spite of high internal quantum efficiency of GaN-based LED, the external quantum efficiency is still low due to the total internal reflection of the light at the semiconductor-air interface. To improve the probability of escaping the photons outside from the LED structure, we fabricated nano-sized cavities on a p-GaN surface utilizing Pt self-assembled metal clusters as an etch mask. Electroluminescence measurement showed that the relative optical output power was increased up to 80% compared to that of LED without nano-sized cavities. I-V measurement also showed that the electrical performance was improved. The enhanced LED performance was attributed to the enhancement of light escaping probability and the decrease of resistance due to the increase in contact area.

• Journal of Electrochemical Science and Technology
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• 제9권2호
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• pp.118-125
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• 2018

Herein we report on the selective synthesis and direct growth of nanostructures using an aqueous chemical growth route. Specifically, Al-doped ZnO (AZO) nanoflakes (NFs) are vertically grown on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) sheets at low temperature and ambient environment. The morphological, optical, and electrical properties of the NFs are investigated as a function of the Al content. Furthermore, these AZO-NFs are integrated into perovskite solar devices as the electron transport layer (ETL) and the fabricated devices are tested for photovoltaic performance. It was determined that the doping of AZO-NFs significantly increases the performance metrics of the solar cells, mainly by increasing the short-circuit current of the devices. The observed enhancement is primarily attributed to the improved conductivity of the doped AZO-NF, which facilitates charge separation and reduces recombination. Further, our flexible solar cells fabricated through this low temperature process demonstrate an acceptable reproducibility and stability when exposed to a mechanical bending test.

• 한국태양에너지학회 논문집
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• 제34권3호
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• pp.82-88
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• 2014

Using low outdoor temperature, free cooling system is used in a data center or industrial air-conditioning for energy saving. Because use of IT equipment has increased in some office building recently, there is a growing trend towards using free cooing system. Free cooling system performance is influenced by outdoor temperature. Therefore the performance is different with regions. In this study, performance characteristic of free cooling system is analysed and energy reduction is compared with some regions. Selected regions are 4 cities; including Ulsan analyzed in preceding research, Seoul, ChunCheon and Daejeon. The Aspentech software HYSYS 8.0v was used to conduct the analysis of free cooling system based on temperature per hour of 4 cities in 2013, respectively. The main result is following as. Free cooing system in this study has energy saving effect when outdoor temperature below $7^{\circ}C$. Becuase temperature of Chuncheon is relatively low, using free cooling system can conserve most air-conditioning energy. Energy reduction amount of Seoul is 11%, Chuncheon is 17.5%, Deajeon is 15%, Ulsan is 14%. In case of large scale of air-conditioning, it is reasonable to use free cooling system although the system is used in Seoul.

• 품질경영학회지
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• 제46권3호
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• pp.425-440
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• 2018

Purpose: This study is aimed at developing of the flex resistance testing process at low temperature with the waterproof fabric to suit the military environment, and is designed to fit for the purpose of the waterproof materials in order to optimize the test method by finding out matters to improve from existing the test method and through previous studies. Methods: The test method, which has been applied to flex resistance of existing water-repellent materials, was improved and consequently, differentiated test results could be obtained according to the test temperature, sample size, and flexing method. Results: The testing of the total of 8 samples revealed that performance of the military requirement could hardly be met just by presenting the materials or 2~3 layers when the quality criteria for high functional water repellent fabrics were applied. PTFE(Polytetrafluoroethylene) is preferred to PU(Polyurethane) to be used in the extremely low-temperature environment, but durability under the low-temperature environment may be varied depending on film thickness or laminating technique even if the materials of waterproof films are identical. Therefore, in addition to the material or texture, the test method capable of reflecting durability under the low-temperature environment shall be suggested, and the newly designed test method proposed in this study was shown to suggest differentiated quality criteria by the material. Conclusion: The water resistance measurement and the test method following flex resistance with expanded range of flex will enable the differentiable test of the samples according to the number of repetition. This study is meaningful in that it suggests a differentiable test method capable of establishing a basis of deciding suitable material when selecting military goods made of water repellent material by properly improving the test method.

• 한국태양에너지학회 논문집
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• 제22권1호
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• pp.73-80
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• 2002

This is study of the planning of thermal insulation to prevent heat loss in a basement, is aimed at investigating the heat loss from the basement space and basement structures. The results analyzed in these researches are as follows; To analyze the heat loss from basement structures, this study experimented on the heat flow phenomenon of a non-insulation structure and two insulation structure models. From the result, the interior surface temperature of two insulation structures(B, C, model) showed an equal temperature, but the interior surface temperature of a non-insulation structure (A model) is different from the two models, Therefore, we understand that the insulator constructed in the basement structure makes a role of preventing the heat loss from the basement. In addition, the exterior surface temperature of two insulation structure models showed an equal temperature. Specially, judging from the temperature difference of C model. we understand that the performance of insulator is low under the definite depth of underground. The thermal insulation design should be constructed under the definite depth of underground considering outdoor and building conditions.

• 마이크로전자및패키징학회지
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• 제29권2호
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• pp.1-10
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• 2022

최근 반도체 소자는 모바일 전자제품과 wearable 및 flexible한 소자와 기판의 다양한 활용으로 많은 분야에서 폭넓게 사용되고 있다. 이들 반도체 칩 접합 공정 중 기판과 솔더의 열팽창 계수(CTE)의 차이와 기판 및 부품 전체에 인가되는 과도한 열 영향은 소자의 성능 및 신뢰성에 영향을 주며, 최종적으로 휨(warpage) 현상 및 장기 신뢰성 저하 등을 초래한다. 이러한 문제점을 개선하기 위해 저온에서 공정이 가능한 저융점 솔더에 대한 연구가 활발히 진행되고 있다. Sn-Bi, Sn-In 등 다양한 저융점 솔더 합금 중 Sn-Bi 솔더는 높은 항복 강도, 적절한 기계적 특성 및 저렴한 가격 등의 이점이 있어 유망한 저온 솔더로 각광받고 있다. 그러나 Bi의 높은 취성 특성 등 단점으로 인해 솔더 합금의 개선이 필요하다. 본 review 논문에서는 다양한 미량 원소와 입자를 첨가하여 Sn-Bi 소재의 기계적 특성 개선을 위한 연구 동향을 소개하며 이를 비교 분석하였다.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.551-557
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• 2013

The heat transfer performance and pressure drop characteristics of brazed-plate heat exchangers with 20 and 30 plates were experimentally measured and analyzed in this study. The mass flow rates of the heat exchangers with 20 and 30 plates were fixed at 0.6 and 0.9 kg/s for the low temperature side, respectively. The mass flow rate for the high temperature side was controlled from 0.2 kg/s to 1.2 kg/s. The inlet temperatures for the high and low temperature sides were $10^{\circ}C$ and $7^{\circ}C$, respectively. The heat transfer characteristics were not influenced by the number of plates. The pressure drop at the heat exchanger with 30 plates was slightly higher than that with 20 plates. The values calculated from the correlations based on gasket plate heat exchangers were compared with the experimental results. It was found that the predicted Nusselt numbers for the gasket plate heat exchangers were about 5% to 20% lower than the measured Nusselt numbers for the brazed plate heat exchangers. However, a pressure drop comparison showed that the calculated pressure drops at the gasket plate heat exchangers were less than half of the measured pressure drops at the brazed plate heat exchangers.

• 한국수산과학회지
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• 제46권4호
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• pp.399-406
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• 2013

Our aim was to determine the effects of a citrus by-product (CBP) and CBP fermented by Lactobacillus plantarum (LP-CBP), provided as dietary supplements, on the growth performance, feed utilization, innate immunity and temperature tolerance of red seabream. A diet without inclusion of CBP or LP-CBP was used as a control and four other experimental diets were formulated to replace wheat flour by 4% and 8% of either CBP or LP-CBP (designated as Con, LP-CBP4%, LP-CBP8%, CBP4% and CBP8%, respectively). Experimental diets were fed to triplicate groups of 25 fish (initial body weight, 55.0 g) for 9 weeks. Growth performance and feed utilization were not significantly different among all the groups. Bone collagen content was significantly increased by supplementation with CBP and LP-CBP. Vitamin C concentration tended to be higher in livers of fish fed the supplements than in the control group. Myeloperoxidase, lysozyme and superoxide dismutase activities were higher in fish fed CBP or LP-CBP than in fish fed the control diet. When fish were exposed to low water temperature, cumulative mortalities of those fed CBP or LP-CBP supplemented diets were lower (29%, 33%, 34% and 33% mortalities for LP-CBP4%, LP-CBP8%, CBP4% and CBP8%, respectively) than in the control group (58%). Therefore, inclusion of either CBP or LP-CBP at up to 8% in red seabream diet brings benefits through enhanced innate immunity and better tolerance of low water temperature.