• Journal of Advanced Marine Engineering and Technology
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• 제30권1호
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• pp.22-29
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• 2006

Gas turbine engine among Principal internal combustion engines has been mainly applied as an aero and industrial Power plant. In order to increase its thermal efficiency. it has been raised their pressure ratio of compressor and the turbine inlet temperature. To operate above the limit temperature of turbine material, turbine nozzle vanes should be cooled. For this the cooling air is bled from the compressor section of 9as turbine. Meanwhile, to keep high thermal efficiency of 9as turbine, turbine vanes are to be cooled by using small cooling air Therefore, the complex cooling passages are requested to be designed and evaluated the effectiveness of vane cooling by measuring turbine vane temperature. But it is very difficult or impossible for us to measure local turbine temperatures at actual temperature When local heat transfer coefficients are known these can be calculated, therefore this study has been investigated on obtaining these coefficients of turbine vane at room temperature using TLC.

• 대한기계학회논문집B
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• 제30권12호
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• pp.1147-1154
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• 2006

An experimental investigation was conducted to enhance the heat/mass transfer for impingement/effusion cooling system when the initial crossflow was formed. For the improvement of heat transfer, the circular guide is installed on the injection hole. At the fixed jet Reynolds number of 10,000, the measurements were carried out for blowing ratios ranging from 0.5 to 1.5. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The result presents that the circular guide protects the injected jet from the initial crossflow, increasing the heat/mass transfer. The heat transfer of stagnation region is hardly changed regardless of the blowing ratio. The secondary peak is obviously formed by flow transition to turbulent flow. At high blowing ratio of 1.5, the circular guide produces $26{\sim}30%$ augmentation on the averaged heat/mass transfer while the case without circular guide leads to the low and non-uniform heat/mass transfer. With the increased heat/mass transfer, the installation of circular guide is accompanied by the increase of pressure loss in the channel. However, the pressure drop caused by the circular guide is lower than that for other cooling technique with the circular pin fin.

• Nuclear Engineering and Technology
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• 제46권2호
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• pp.225-234
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• 2014

Wall-thinned defects caused by accelerated corrosion due to fluid flow in the inner pipe appear in many structures of the secondary systems in nuclear power plants (NPPs) and are a major factor in degrading the integrity of pipes. Wall-thinned defects need to be managed not only when the NPP is under maintenance but also when the NPP is in normal operation. To this end, a test technique was developed in this study to detect such wall-thinned defects based on the temperature difference on the surface of a hot pipe using infrared (IR) thermography and a cooling device. Finite element analysis (FEA) was conducted to examine the tendency and experimental conditions for the cooling experiment. Based on the FEA results, the equipment was configured before the cooling experiment was conducted. The IR camera was then used to detect defects in the inner pipe of the pipe specimen that had artificially induced defects. The IR thermography developed in this study is expected to help resolve the issues related to the limitations of non-destructive inspection techniques that are currently conducted for NPP secondary systems and is expected to be very useful on the NPPs site.

• Journal of Welding and Joining
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• 제3권1호
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• pp.11-21
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• 1985

The line heating is a thermoplastic working technique which is used in bending work of steel plate and in correcting the distortion of welded structure. This method is considerably effective when the water-cooling is followed. In this study, an investigation was accomplished to find the effects on the change of material properties when the line heating was applied on the high tensile steel plate of 50kg/mm^2$ grade. Some steel plates were heated to various temperatures and then cooled with water or in the air. In this study, the author measured the angular distortion continuously during line heating to find out the relation between the bending efficiency and heating or water-cooling temperature. Furthermore, its material properties were examined by the V-notch Charpy impact test, the microscope observation and the Vickers hardness test. As results, the followings were clarified. (1) The amount of angular distortion increases as the heating temperature or the water-cooling temperature rises. (2) When the steel plate is heated between 700.deg. C and 900.deg. C, and then is water-cooled over 700.deg. C, some brittle structure is observed. But if the temperature of water-cooling is below 700.deg. C, no brittle one is found. (3) When the steel plate is heated over 800.deg. C and is cooled in the air, there is no unfavrable effect.

• 한국재료학회지
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• 제30권12호
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• pp.693-700
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• 2020

Direct water quenching technique can be used in hot stamping process to obtain higher cooling rate compared to that of the normal die cooling method. In the direct water quenching process, setting proper water flow rate in consideration of material thickness and the size of the area directly cooled in the component is important to ensure uniform microstructure and mechanical properties. In this study, to derive proper water flow rate conditions that can achieve uniform microstructure and mechanical properties, microstructure and hardness distribution in various water flow rate conditions are measured for 3.2 mm thick boron steel sheet. Hardness distribution is uniform under the flow condition of 1.5 L/min or higher. However, due to the lower cooling rate in that area, the lower flow conditions result in a drastic decrease in hardness in some areas in the hot-stamped part, resulting in low martensite fraction. From these results, it is found that the selection of proper water flow rate is an important factor in hot stamping with direct water quenching process to ensure uniform mechanical properties.

• Asian-Australasian Journal of Animal Sciences
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• 제4권2호
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• pp.131-136
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• 1991

Four male swamp buffaloes weighing $460.5{\pm}44.6kg$ were used to study the effects of different cooling techniques on draught capacity. Each animal carted an 882 kg load on the same asphalt road for one hour during four different time periods: 9:00-10:00 A.M., 10:30-11:30 A.M., 2:00-3:00 P.M. and 3:30-4:30 P.M. Simultaneously, all animals were subjected to five different treatments on five days of similar environmental conditions. In Treatment 1, animals were put stationary in a field and did no work; in Treatment 2, animals were worked without any cooling method; in Treatment 3, fifteen-minute wallow was allowed to animals prior to working; in Treatment 4, animals were covered with wetted jute bags while working, and in Treatment 5, two buckets of water were poured over the buffaloes' trunks just prior to working. The experiment was conducted from April to July 1989, when the weather was very hot. It was found that cooling methods and working times did not affect the draught efficiency of buffaloes during the one hour, but did affect physiological traits. The work load had a larger partial effect on physiological responses of buffalo other than respiration rate than did climatic variables except on the respiration rate of the buffaloes. One cooling technique that seemed to slow the increase of body temperature while working was covering the buffalo's back with wetted jute bags. Animals working at different times had significant differences in the increase of physiological traits except pulse rate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.304-310
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• 2010

본 연구에서는 딤플이 설치된 유로, 립이 설치된 유로, 립과 딤플이 함께 설치된 유로에서의 열전달 성능을 천이액정법을 이용하여 측정하였다. 실험에 사용된 유로의 종횡비(W/H)는 4이고, 립의 높이는 6 mm, 립 간 거리(P/e)는 10, 립이 설치된 각도는 $60^{\circ}$이며, 딤플의 직경은 6 mm, 딤플 중심간 거리(s/D)는 1.2로 하였다. 레이놀즈 수는 30000-50000에 대해 실험을 수행하였다. 립이 설치된 유로에서는 경사 립에 의해 발생된 이차유동이 열전달 계수를 증가시켰고, 립과 딤플이 함께 설치된 유로에서는 립 사이에 설치된 딤플이 열전달 계수를 더욱 증가시켰다. 열전달계수는 립과 딤플이 복합 적용된 유로, 립이 적용된 유로, 딤플이 적용된 순으로 나타났고, 열성능계수도 립과 딤플이 복합 적용된 유로에서 크게 나타났다.

• 한국추진공학회지
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• 제14권4호
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• pp.32-38
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• 2010

본 연구에서는 딤플이 설치된 유로, 립이 설치된 유로, 립과 딤플이 함께 설치된 유로에서의 열전달성능을 천이액정법을 이용하여 측정하였다. 실험에 사용된 유로의 종횡비(W/H)는 4이고, 립의 높이는6 mm, 립 간 거리(P/e)는 10, 립이 설치된 각도는 $60^{\circ}$이며, 딤플의 직경은 6 mm, 딤플 중심간 거리(s/D)는 1.2로 하였다. 레이놀즈 수는 30000-50000에 대해 실험을 수행하였다. 립이 설치된 유로에서는 경사 립에 의해 발생된 이차유동이 열전달 계수를 증가시켰고, 립과 딤플이 함께 설치된 유로에서는 립 사이에 설치된 딤플이 열전달 계수를 더욱 증가시켰다. 열전달계수는 립과 딤플이 복합 적용된 유로, 립이 적용된 유로, 딤플이 적용된 순으로 나타났고, 열성능계수도 립과 딤플이 복합 적용된 유로에서 크게 나타났다.

• 전자공학회논문지A
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• 제31A권2호
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• pp.81-87
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• 1994

We used IR laser inteferometric technique for measuring the temperature of wafer during cryogenic ECR etching. Using this technique, the effect of RF bias power and microwave power on the wafer temperature during etching period is investigated. As the RF bias power and microwave power was increased, the temperature of the wafer considerably increased and we concluded that to prevent the increase of substrate temperature during etching period, an adequate wafer cooling is needed.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 임시총회 및 하계학술연구발표회
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• pp.66-67
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• 2013