• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.823-824
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• 2016

In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact of bus bar, deterioration of the contact resistance, overtemperatue of the bus bars. In this paper, we propose bus bar joints monitoring system with loose connection of bus bar, measuring the joint resistance of busbars and monitoring internal and external heat. The proposed system can be reduced the electrical accidents by maintenance of busbar joints and the temperature of the conductive contact surface of busbars.

• Journal of Bio-Environment Control
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• v.6 no.3
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• pp.216-224
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• 1997

In the recent 10 years the protected cultivation area in Korea has been increased rapidly, and now it is very important issue to develop the heating and cooling system using the renewable energy, because the greenhouse heating and cooling cost is increased with the fossil fuel price rises. Actually the development of the cooling system is more difficult than that of the heating system, since the cooling load of greenhouse in the summer season is 2―3 times larger than the heating load in the winter season. In this study low temperature phase change materials (LTPCM) for the cold storage system were selected and developed. The theoretical and experimental analysis of thermal characteristics of LTPCM makes it possible to control the phase change temperature and stabilize the thermo-physical properties. LTPCM developed in this study has good advantages to be used as the cold storage not only for the house and working space in factory but also for the cold storage of agricultural and live-stock products.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.3
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• pp.130-137
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• 2023

Smart farms, which have been receiving attention as a solution to recent rural problems, refer to technologies that optimize the growing environment of crops and increase the productivity and quality of crops through efficient management. If the relationships between environmental data in smart farms are analyzed, additional productivity enhancement and crop management will be possible. In this paper, we propose a method for acquiring and analyzing nine environmental data, including temperature, humidity, CO2, soil temperature, soil moisture, insolation, soil EC, EC, and pH. Data acquisition is done through RS-485 communication between the main board and the sensor board and stored in the database after acquisition. The stored data is downloaded in Excel sheet format and analyzed through histograms, data charts, and correlation heatmaps. First, we analyze the distribution of total, day, and night data through histogram analysis, and identifiy the average, median, minimum, and maximum values by month through data chart analysis separating day and night to see how the data changes by month. Finally, we analyze the correlation of the data through a correlation heatmap analysis separating day and night. The results show a very strong positive correlation between temperature and soil temperature and soil EC and EC during the day, and a very strong positive correlation between temperature and soil temperature and soil EC and EC at night, and a strong negative correlation between temperature and soil EC.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.327-328
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• 2012

의료분야의 진단 방사선 장비는 초기의 필름방식 및 카세트에서 진보되어 현재는 디지털방식의 DR (Digital Radiography)이 널리 사용되며 이에 관한 연구개발이 활발히 진행 되고 있다. DR은 일반적으로 직접방식과 간접방식으로 나눌 수 있다. 직접방식의 원리는 X선을 흡수하면 전기적 신호를 발생 시키는 광도전체(Photoconductor)를 사용하여 광도전체 양단 전극에 전압을 인가하여 전기장을 유도한 가운데, X선을 조사하면 광도전체 내부에서 전자-전공쌍(Electron-hole pair)이 생성된다. 이것은 양단에 유도된 전기장의 영향으로 전자는 +극으로, 전공은 -극으로 이동하여 아래에 위치한 하부기판을 통하여 이미지로 변조된다. 간접방식은 X선을 흡수하면 가시광선으로 전환하는 형광체(Scintillator)를 사용하여 조사된 X선을 형광체에서 가시광선으로 전환하고, 이를 Photodiode와 같은 광변환소자로 전기적 신호로 변환하여 방사선을 검출하는 방식을 말한다. 본 연구에서는 직접방식에서 이용되는 광도전체 중 흡수효율이 높고 Mobility가 뛰어난 CdTe를 선정하여 PVD (Physical vapor deposition)방식으로 300 m의 두께를 목표로 하여 증착을 진행하였다. Chamber의 진공도가 $2.5{\times}10^{-2}$ Torr로 도달 시점부터, Substrate와 Boat에 열을 가하였다. Substrate온도는 $350^{\circ}C$, Boat온도는 $300^{\circ}C$도로 설정하여 11시간 동안 진행하였다. Substrate온도는 $303^{\circ}C$, Boat온도는 $297^{\circ}C$도부터 증착이 시작되어 선형적인 증가세 추이를 나타내어 Substrate 및 Boat온도가 설정 값에 도달 하였을 때, $25{\sim}34.4{\AA}/s$ 증착율을 나타내었다. 하부전극의 물질에 따른 CdTe증착 효율성 평가를 진행한 후, 그에 따른 전기적 특성을 알아보았다. 하부전극의 물질로는 ITO (Indium Tin Oxide), Parylene이 코팅 된 ITO, Au, Ag를 사용하였다. 하부전극의 물질 상단에 Thermal Evaporation System을 사용하여 CdTe를 증착한 후, Cdte 상단에 Au를 증착 시켜 민감도(Sensitivity)와 암전류(Dark current)를 측정하였다. 증착 결과 ITO와 Ag상단에 증착시킨 CdTe박막은 박리가 되었고, Au와 Parylene이 코팅 된 ITO에는 CdTe박막이 안정적이게 형성이 되었다. 이 두 샘플에 대하여 동일한 조건으로 민감도와 암전류를 측정 시, Parylene이 코팅된 ITO를 하부전극으로 사용한 CdTe박막은 0.1021 pA/$cm^2$의 암전류와 1.027 pC/$cm^2$의 민감도를 나타낸 반면, Au를 하부전극으로 사용한 CdTe박막은 0.0381 pA/$cm^2$의 암전류와 1.214 pC/$cm^2$의 민감도를 나타내어 Parylene이 코팅된 ITO보다 우수한 전기적 특성을 나타내었다. 따라서 Au는 CdTe박막 증착 시, 하부전극 기판으로서 뛰어난 특성을 나타내는 것을 알 수 있었다.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.136-146
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• 1999

A series of experiments were carried out in winter to investigate the indoor thermal environment in greenhouses with different kinds of heating systems, and characterize the energy consumption, heat transport and thermal energy efficiency of each system. By the Quantitative calculation of heat losses which transmit through the covers of greenhouse, the fundamental data of energy-saving of the particular heating system were obtained. And from the analysis of air temperature differences between indoor and outside, it was possible to select more effective energy-saving and comfortable heating system in greenhouses. The electric heater was more stable in thermal environment and cheaper in cost, since it could be used during the surplus time of electric power from 10：00 p.M. to 8：00 A.M. But the low air temperature in greenhouses besides these times resulted in a chilling problem of the crops. The heating system by hot air had the advantage to show nearly uniform temperature difference by the height above the ground. But the system had the disadvantage to require more energy consumption than the electric heating system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.277-284
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• 2012

In this study, a heat-transfer performance analysis is carried out for a multi-channel volumetric air receiver for a solar power tower. On the basis of a series of reviews regarding the relevant literature, a calculation process is proposed for the prediction of the wall- and air- temperature distributions of a single channel at given geometric and input conditions. Furthermore, a unique mathematical model of the receiver effectiveness is presented through analysis of the temperature profile. The receiver is made of silicon carbide. A total of 225 square straight channels per module are molded to induce the air flow, and each channel has the dimensions of $2mm(W){\times}2mm(H){\times}0.2mm(t){\times}320mm(L)$. The heat-transfer rate, temperature distribution and effectiveness are presented according to the variation of the channel and module number under uniform irradiation and mass flow rate. The available air outlet temperature applied to the solar power tower should be over $700^{\circ}C$. This numerical model was actually used in the design of a 200 kW-level commercial solar air receiver, and the required number of modules satisfying the thermal performance could be obtained for the specified geometric and input conditions.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.75-82
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• 2004

Surface and bottom sea water samples were harvested from the 5 stations in the marine ranching ground of Tongyeong coastal water from year 2000 to 2002. Cell number of heterotrophic bacteria was determined by using the plate counting method to explore the variation of the cell population of heterotrophic bacteria. Sea water samples collected in summer (in July and August) contained much larger number of heterotrophic bacteria than those harvested in spring, autumn and winter. Heterotrophic bacteria were usually more abundant in surface sea than in bottom sea water. However the reverse was true for sea water collected in December 2001 and February 2002 due to suspended solids accumulating more abundantly in seabed area because of the slower convective current of the sea water in winter. Number of heterotrophic bacteria did not have a strong relationship with frequency of typhoon indicating that the path and powerfulness of the typhoon, localized torrential downpour and temperature variation accompanying the typhoon should be considered all together at the same time as well as the frequency of typhoon to explain clearly the variation of cell number of heterotrophic bacteria. The dominant species isolated from the marine ranching ground of Tongyeong were identified to be Pseudomonas fluorescens, Pseudomonas stutzeri, Acinetobacter lwoffii and Sphingomonas paucimobilis.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.23-27
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• 2004

The $Al_xTa_{1-x} (x=0.0{\~}1.0)$ alloy thin films were deposited by RF-magnetron sputtering system, and the crystal quality, surface morphology, and electrical properties were examined using XRD, AFM, 4-point probe techniques in this study. The thin films were grown according to the alloy compositions first, and the effects of film thickness and mask patterns were investigated afterwards. Also, the heating characteristics were examined by heat controller. The obtained results showed that the high electrical resistivity was obtained for Al content $x=6.63at\%$, and the even higher resistivity was accomplished for the samples with smaller thickness and narrower width. The heating temperature demonstrated the identical trend to the electrical properties, and the highest heating temperature ($400^{\circ}C$) and output power ($12.6W/cm^2$) were obtained for the sample with Al content $x=6.63\%$, film thickness d=500 nm, film width w=1.5 mm.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.311_312
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• 2009

개폐장치중 GIS는 전력기술발전과 함께 국토가 좁고 도심이 갑작스럽게 팽창되는 우리나라 현실에서 빠르게 보급되어 운전되고 있는 실정이다. 우리나라의 GIS의 도입은 1970년대말 유럽으로부터 Maintenance Free 목적으로 도입되었고 800kV급까지 국산화에 성공하여 국내 및 세계전력시장에 보급되고 있다. 그러나 GIS Trouble도 다양하게 발생하고 있으며 그중에서도 한국전력에서 조사한 2000년이후 MV급(25.8kV) GIS Trouble 이력을 조사한 결과 조작기구부와 조작회로의 Trouble이 크게 차지하고 있으며 조작기구부와 조작회로를 구성하는 주요부품의 Trouble에서 기인된 것으로 나타나고 있다. 이에 따라 향후 도입될 예정인 MV급 친환경절연 개폐장치는 이러한 문제를 해결하고자 조작회로는 전력IT의 산물인 IED를 도입하였고 조작기구부는 사용환경 상태보다 약간 상회하는 온도와 습도변화를 통하여 구성하는 유기물 부품에 대한 가속열화를 촉진시켜 동작시간과 Stroke의 동작변화 추이를 확인하는 고, 저온 동작특성시험을 도입하게 되었다.

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.58-62
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• 2016

The satellite propulsion system provides the required thrust to insert a satellite into the desired orbit after separation from the launch vehicle and to control orbit inclination or compensate altitude loss due to drag after inserted into the desired orbit. The on-orbit performance of LEO satellite propulsion system according to operation mode was verified based on the results analysis for early on-orbit operation. The temperature trends of components and tubing were checked and the resultant trends were within the normal range as well.