• Journal of Biosystems Engineering
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• 제21권4호
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• pp.436-448
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• 1996

An earth tube soil air heat exchange system was designed, installed and operated as a single pass heat exchanger to utilize the geothermal energy as an natural energy source. This study was undertaken to investigate the potential of the heating and cooling, energy gain, heat exchange efficiency and coefficient of performance of the system. The system consisted of 30m in length and 30cm in diameter polyethylene pipes buried 2m deep in soil. Maximum heating and cooling performance were 2.51㎾ and 1.26㎾ at the air mass rate of 21cmm. Energy gain and coefficient of performance were the function of temperature difference between outside air and soil temperature. They were expressed as Q=0.33$ imes$$Delta T_{max}$+0.134(㎾) for energy gain and COP=0.44$ imes$$Delta T_{max}$+0.178 for coefficient of performance with correlation factor of 0.95. The mean of heat exchange efficiencies was 85.6%.

• 동력기계공학회지
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• 제20권1호
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• pp.11-17
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• 2016

In this study, the simulation for performance comparison between basic single stage organic rankine cycle, multi stage reheater cycle and multi stage reheater & recuperator cycle was carried out. The multi stage reheater cycle and multi stage reheater & recuperator cycle was designed to improve the efficiency for organic rankine cycle using heat source from industrial waste heat and heat sink from deep ocean water. R245fa was selected as a refrigerant for the cycle and system efficiencies were simulated by the variation of the heat sink temperature and the cycle classification. Performance characteristics were simulated by using the Aspen HYSYS. It was confirmed that the system efficiency was decreased by the increase of heat sink temperature. These results can be considered to be applied as geo-ocean thermal energy conversion in where plenty of geothermal or ocean thermal resource exist.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.139-140
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• 2013

Ground source heat pump systems can achieve the energy saving of building and reduce CO₂ emission by utilizing stable ground temperature. However, they have many barriers such as high cost of installation, incompletion of design tool, lack of recognition as heating and cooling systems. In order to solve the problems, the building integrated geothermal system (BIGS) developed by several researches which use building foundation as a heat exchanger. In order to establish the optimum design tool of BIGS with the horizontal heat exchanger, the prediction method of ground heat exchange rate developed with numerical simulation model. In this study, the economic analysis for BIGS was conducted based on simulation results and the optimal design method was suggested. As a result, it was found that the case of 32 A, piping space 0.3 m, piping deep 0.5 m and flow rate 9.52 L/min was the best case as 50.1 W/m2 of heat exchange rate. In this case the initial cost was reduced to 115 million won.

• 스마트미디어저널
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• 제9권3호
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• pp.46-51
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• 2020

소나무 재선충은 한국과 일본, 중국을 포함한 동아시아 지역의 소나무산림에 막대한 피해를 주는 원인이며, 피해목의 조기 발견과 제거는 재선충 확산을 막는 효과적인 방법이다. 본 논문에서는 드론으로 촬영되고 처리된 RGB 정사영상을 딥러닝 분류에 의한 재선충 피해목 탐색방법을 제안한다. 제안된 방법은 학습영상 데이터가 많지 않다는 가정아래 ResNet18을 백본으로 하는 패치기반의 분류기를 구성하고 RGB 정사영상을 분류하고 그 결과를 heatmap 형태로 만든다. 제작된 정사영상의 heat map는 재선충 피해목의 분포를 알아내고 확산해가는 모습을 관찰할 수 있게 하며, 재선충 피해목 지역의 RGB 분포 특징을 추출해낼 수도 있다. 본 연구의 패치기반 분류기 성능은 94.7%의 정확도를 나타내었다.

• 한국정밀공학회지
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• 제23권9호
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• pp.164-173
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• 2006

The cooling capacity of a micro-heat pipe is mainly governed by the magnitude of capillary pressure induced in the wick structure. For microchannel wicks, a higher capillary pressure is achievable for narrower and deeper channels. In this study, a metallic micro-heat pipe adopting high-aspect-ratio microchannel wicks is fabricated. Micromachining of high-aspect-ratio microchannels is done using the laser-induced wet etching technique in which a focused laser beam irradiates the workpiece placed in a liquid etchant along a desired channel pattern. Because of the direct writing characteristic of the laser-induced wet etching method, no mask is necessary and the fabrication procedure is relatively simple. Deep microchannels of an aspect ratio close to 10 can be readily fabricated with little heat damage of the workpiece. The laser-induced wet etching process for the fabrication of high-aspect-ratio microchannels in 0.5mm thick stainless steel foil is presented in detail. The shape and size variations of microchannels with respect to the process variables, such as laser power, scanning speed, number of scans, and etchant concentration are closely examined. Also, the fabrication of a flat micro-heat pipe based on the high-aspect-ratio microchannels is demonstrated.

• 설비공학논문집
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• 제17권2호
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• pp.173-182
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• 2005

The Performance of U-tube ground heat exchanger for geothermal heat Pump systems depends on the thermal properties of the soil, as well as grout or backfill materials in the borehole. In-situ tests provide a means of estimating some of these properties. In this study, in-situ thermal response tests were completed on two vertical boreholes, 130 m deep with 62 mm diameter high density polyethylene U-tubes. The tests were conducted by adding a monitored amount of heat to water over a $17\~18$ hour period for each vertical boreholes. By monitoring the water temperatures entering and exiting the loop and heat load, overall thermal conductivity values of grout/soil formation were determined. Two parameter estimation models for evaluation of thermal response test data were compared when applied on the same temperature response data. One model is based on line-source theory and the other is a numerical one-dimensional finite difference model. The average thermal conductivity deviation between measured data and these models is of the magnitude $1\%$ to $5\%$.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.24-29
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• 2003

Deep sea water has cold temperature, abundant nutrients and minerals, and good water quality that is pathogen-free and stable. Compared with surface water, deep sea water contains more nutrition salt, such as nitrogen and phosphor. Moreover, if has the good balance of minerals. Because of the ability of the spray drying process to produce a free-flowing power considering of spherical particles with a well-defined size distribution and the rapid drying times for heat-sensitive material, spray drying is attractive for a wide range of applications spray drying is a unique unit operation in which powders are produced from a liquid feed in a single processing step. Key component of the process are atomizer, spray chamber. Design of spray chamber should be based on the atomizer type, the production rate, and the particle size required. Because of the complex processes taking place during spray drying, traditional design method are based on pilot-plant tests and empirical scale-up rules. Modern technique such as CFD have a role to play in design and troubleshooting.

• 한방안이비인후피부과학회지
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• 제20권1호통권32호
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• pp.285-293
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• 2007

Burn is a dermal injury mainly caused by heat. It occurs by flame, boiling water or liquid, steam, sparks, chemicals, radiation, and electricity. Burn is classified as four grades depending on how deep into the skin a person is burned. As the deep second-degree burns possibly leave scars, it can have various physical, psychological, and aesthetical effects with seriousness on the patient with a burn. This report is on the 50-year-old female patient who had a burn with boiling water and a mixture condition of superficial and deep second degree burn. The Korean medical treatments such as Herbal acupuncture, Herbal medication, Acupuncture, Herbal-ointment were used for 17 days to treat effectively the patient with a mixture of superficial and deep second degree burn. It is difficult to find out the report that treats a burn with Korean medical treatment. If more clinical treatments as in this report are proved to be effective, we are able to expect that Korean medical treatment should be a good treatment in burn.

• 센서학회지
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• 제33권5호
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• pp.298-304
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• 2024

In Korea, fires are the second most common type of disaster, causing large-scale damages. The installation of fire detectors is legislated to prevent fires and minimize damage. Conventional fire detectors have limitations in initial suppression of failures because they detect fires when large amounts of smoke and heat are generated. Additionally, frequent malfunctions in fire detectors may cause users to turn them off. To address these issues, recent studies focus on accurately detecting even small-scale fires using multi-sensor and deep-learning technologies. They also aim at quick fire detection and thermal decomposition using gas. However, these studies are not practical because they overlook the heavy computations involved. Therefore, we propose a fast and accurate fire detection system based on multi-sensor and deep-learning technologies. In addition, we propose a computation-reduction method for selecting sensors suitable for detection using the Pearson correlation coefficient. Specifically, we use a moving average to handle outliers and two-stage labeling to reduce false detections during preprocessing. Subsequently, a deep-learning model is selected as LSTM for analyzing the temporal sequence. Then, we analyze the data using a correlation analysis. Consequently, the model using a small data group with low correlation achieves an accuracy of 99.88% and a false detection rate of 0.12%.

• Nuclear Engineering and Technology
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• 제55권4호
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• pp.1540-1554
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• 2023

To use nuclear energy sustainably, spent nuclear fuel, classified as high-level radioactive waste and inevitably discharged after electricity generation by nuclear power plants, must be managed safely and isolated from the human environment. In Korea, the land area is limited and the amount of high-level radioactive waste, including spent nuclear fuels to be disposed, is relatively large. Thus, it is particularly necessary to maximize disposal efficiency. In this study, a high-efficiency deep geological repository concept was developed to enhance disposal efficiency. To this end, design strategies and requirements for a high-efficiency deep geological repository system were established, and engineered barrier modules with a disposal canister for pressurized water reactor (PWR)-type and pressurized heavy water reactor type Canada deuterium uranium (CANDU) plants were developed. Thermal and structural stability assessments were conducted for the repository system; it was confirmed that the system was suitable for the established strategies and requirements. In addition, the results of the nuclear safety assessment showed that the radiological safety of the new system met the Korean safety standards for disposal of high-level radioactive waste in terms of radiological dose. To evaluate disposal efficiency in terms of the disposal area, the layout of the developed disposal areas was assessed in terms of thermal limits. The estimated disposal areas were 2.51 km² and 1.82 km² (existing repository system: 4.57 km²) and the excavated host rock volumes were 2.7 Mm³ and 2.0 Mm³ (existing repository system: 4.5 Mm³) for thermal limits of 100 ℃ and 130 ℃, respectively. These results indicated that the area and the excavated volume of the new repository system were reduced by 40-60% compared to the existing repository system. In addition, methods to further improve the efficiency were derived for the disposal area for deep geological disposal of spent nuclear fuel. The results of this study are expected to be useful in establishing a national high-level radioactive waste management policy, and for the design of a commercial deep geological repository system for spent nuclear fuels.