• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.1
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• pp.55-63
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• 1989

A one dimensional analytic model for the prediction of the stratification coefficient of a liquid-based solar heating system is developed. The stratification coefficient, $K_s$, is defined as the ratio of the actual useful energy gain to the energy gain that would be achieved if there were no thermal stratification in the storage tank. Previous studies incorporated only collector-side effects, but in this study both the collector and load-side effects are included for the overall performance evaluation.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2310-2315
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• 2008

In this paper, study on performance analysis of bubble pump on the domestic solar water heater system is presented. Device of this experiment is consisted of bubble pump, solar collector and heat exchanger. At the mean time, this system have attached temperature sensors and pressure sensors at bubble pump. In addition, the flow meter was installed at outlet of heat exchanger. And then result of experimental study, average value of the heat exchange amount in heat exchanger was about 7.9kcal/hr, the maximum value of the heat amount in water tank($0.4m^3$) was 489.7kcal/hr and the maximum value of the mass flow rate in bubble pump was about $0.5{\ell}/min$.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.58-66
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• 2019

Static compound parabolic collectors (CPCs) have advantages such as ease for fabrication and lower cost compared with other concentrating collectors. In this study, thermal performance analysis of CPC employing heat storage tank was carried out. The clearness index and capacity of heat storage tank are taken as the main parameters for numerical simulation. The effects of the parameters on the hourly and daily system performances ncluding the useful energy, heat loss, and collector efficiency were numerically investigated. Results showed that the system has a potential for efficient recovery of solar thermal energy.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.109-113
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• 1999

겨울철 난방에너지와 여름철 냉방에너지 절감을 위한 자갈축열 태양열 온실의 설계자료를 얻고자 모형 자갈축열층과 이론적 해석을 통하여 축열층의 공기유동성 및 자갈축열층의 축열성능을 분석한 결과를 요약하면 다음과 같다. 1. 압출식으로 공기를 유동시켰을 경우 축열층내 풍속은 0.09-l.50㎧(평균 0.60㎧)범위였으며, 흡인식으로 공기를 유동시켰을 경우 축열층내 풍속은 0.15-0.90㎧(평균 0.46㎧)범위로 평균풍속은 압출식이 높게 나타났으나 축열층 가운데에서는 흠인식이 약 0.06㎧정도 높게 나타났다. 이러한 결과로 볼 때 자갈축열층내 공기순환을 위한 별도의 파이프 매설은 불필요한 것으로 판단된다. 2. 자갈축열층의 공극율이 증가할수록 축열량은 감소하였으며 순환팬 용량과 공극율에 따라 평균 2,133㎉/h-3,243㎉/h 정도 축열량 차이가 있는 것으로 나타났다. 3. 공극율이 0.45인 경우 축열층의 높이가 높을수록 자갈축열층의 온도는 서서히 증가하였으며, 축열층 높이 60cm이하에서는 축열 7시간이후부터는 축열량 변화를 거의 없는 것으로 나타났다. 4. 이러한 결과를 모형축열층에 있어 실험적으로 구해지는 축열 자갈층의 온도 및 축열량과의 비교 검증단계를 거쳐 온실규모에 필요한 적정 축열시스템을 산정할 수 있는 시뮬레이션 프로그램의 기초자료로 활용하고자 한다.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.56-62
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• 2010

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. PV/thermal collectors, or more generally known as PVT collectors, are devices that operate simultaneously to convert solar energy from the sun into two other useful energies, namely, electricity and heat. This paper compares the experimental performance of BIPVT((Building-Integrated Photovoltaic Thermal) collectors that applied on building roof and facade. There are four different cases: a roof-integrated PVT type and a facade-integrated PVT type, the base models with an air gap between the PV module and the surface, and the improved models for each types with aluminum fins attached to the PV modules. The accumulated thermal energy of the roof-integrated type was 15.8% higher than the facade-integrated regardless of fin attachment. The accumulated electrical energy of the roof-integrated type was 7.6% higher, compared to that of the facade-integrated. The efficiency differences among the collectors may be due to the fact that the pins absorbed heat from the PV module and emitted it to air layer.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.69-78
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• 2003

In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

• Journal of the Korean Solar Energy Society
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• v.27 no.1
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• pp.47-54
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• 2007

Interests on renewable energy are increased due to oil price and environmental problems aroused from the fossil energy usage. In this study, performances of a solar assisted hybrid heat pump system are analyzed by experimental method. The developed system could runs at two types of operating mode. When the storage temperature is higher than the set temperature, the stored hot water in storage tank is supplied to the load directly. On the other hand, when the storage temperature lower than the set temperature, the water inside of the storage tank is used as heat source of the heat pump. In this study, the system control temperature for the alternation of the operating mode is set to $40^{\circ}C$ of the storage tank outlet. As results, it is founded that the COP of the developed heat pump system shows between 3.0 and 3.5. It is resonable performance for the heating system with a renewable energy as secondary heat source. The solar collect used in this study could supplies heat to the storage tank at over 400 W/m2 solar intensity. If the irradiation is lower than the 400 W/m2, the circulation pump stored and it could not supply heat to the storage tank. It is found that the difference temperature between the outlet of the storage tank and collector is $3^{\circ}C$. Even though, the extended study should be conducted to get a optimum performance of the developed system with various operating condition and control strategies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.657-662
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• 2022

In this paper, the calculation using simulation and two measurement methods for G/T of the telemetry are analyzed. Antenna gain and noise temperature are calculated by using ICARA and Antenna Noise Temperature Calculator. System G/T were calculated by using Antenna gain/noise temperature, LNA gain/noise temperature, cable loss. The first G/T measurement method is Y-factor measurement method, which is to calculate G/T by comparing LNA noise temperature and a signal level difference when an antenna and a 50ohm termination are respectively connected to an LNA input terminal Second method is Solar calibration measurement method that is to calculate G/T by comparing noise level difference when looking at the sun and lowest level point. Finally, the accuracy was reviewed by comparing the G/T calculation results with the two measurement methods, and the optimal measurement method according to antenna performance and operating environment was presented.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.9 no.2
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• pp.93-103
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• 1980

A small domestic solar water heating system in thermosyphonic flow was tested in Seoul. The system consisted of four flat plate aluminium roll bond type collectors of total effective area $3.28m^2$ and a $280{\iota}$ storage tank. It was tilted $52^{\circ}$ relative to the horizon. And the collector plate, collector tube and storage tank were equiped with 14 thermocouples. As the results, the following facts were found; 1) To provide water at $55^{\circ}C$ for a family of four in Seoul, a collector area of $3-4m^2$ and a storage capacity of $180{\iota}- 200{\iota}$ are suggested. And this system can supply hot water at above $45^{\circ}C$ day about. 2) In the late afternoon hours, it might be advantageous to stop the flow in the system as heat losses to the environment increase unduly. 3) Without any hot water consumption throughout the day, water temperature distributions inside the storage tank was found almost linear. This indicates essentially no mixing inside the storage tank. 4) In case of a small domestic solar water heating system, it is better to employ a single transparent cover rather than double one.

• Journal of Internet of Things and Convergence
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• v.10 no.2
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• pp.125-130
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• 2024

With the rapid growth of mobility technology, the industrial sector is demanding storage devices that can reliably process data from various equipment and sensors in vehicles. NAND flash memory is being utilized as a storage device in mobility environments because it has the advantages of low power and fast data processing speed as well as strong external shock resistance. However, flash memory is characterized by data corruption due to long-term exposure to high temperatures. Therefore, a dedicated system for temperature management is required in mobility environments where high temperature exposure due to weather or external heat sources such as solar radiation is frequent. This paper designs a dedicated temperature management system for managing storage device temperature in a mobility environment. The designed temperature management system is a hybrid of traditional air cooling and water cooling technologies. The cooling method is designed to operate adaptively according to the temperature of the storage device, and it is designed not to operate when the temperature step is low to improve energy efficiency. Finally, experiments were conducted to analyze the temperature difference between each cooling method and different heat dissipation materials, proving that the temperature management policy is effective in maintaining performance.