• Bulletin of the Korea Photovoltaic Society
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• v.3 no.1
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• pp.61-67
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• 2017

Concentrated solar power(CSP) is receiving attention for its ability to generate dispatchable power from heat stored in thermal energy storage(TES). There are currently four types of CSP technology, however experts expect that only parabolic trough and solar tower are to survive from the market due to its higher efficiency and larger capacity in storage. While the initial cost for installing CSP plant is still expensive, the experts expect that investment cost of CSP would decline to the level which would be competitive with PV or wind in the near term future. In addition, further growth in its installation capacity is expected due to the United States and China's aggressive investments in CSP.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.263-268
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• 2008

In a residential complex case, the efficiency of land use are maximized, but a variation of external condition such as load in-equality, the increase in wind velocity and solar radiation by a height causes increasing energy in a building. Besides, because of increasing window size for a lighting and a view, it comes heating load in winter and cooling load in summer. A choice of cooling-system is important for this reason. Recently an internal high-rise residential complex installs an air-cooling system and operates individual heating. However, this study applies water-cooling used one public cooling-tower instead of an air-cooling system, also with an efficiency test of an air and a water-cooling system, consider an internal applicability.

• Smart Structures and Systems
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• v.25 no.1
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• pp.23-35
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• 2020

It is important to take into account the thermal behavior in assessing the structural condition of bridges. An effective method of studying the temperature effect of long-span bridges is numerical simulation based on the solar radiation models. This study aims to develop a time-varying solar radiation model which can consider the real-time weather changes, such as a cloud cover. A statistical analysis of the long-term monitoring data is first performed, especially on the temperature data between the south and north anchors of the bridge, to confirm that temperature difference can be used to describe real-time weather changes. Second, a defect in the traditional solar radiation model is detected in the temperature field simulation, whereby the value of the turbidity coefficient t_u is subjective and cannot be used to describe the weather changes in real-time. Therefore, a new solar radiation model with modified turbidity coefficient γ is first established on the temperature difference between the south and north anchors. Third, the temperature data of several days are selected for model validation, with the results showing that the simulated temperature distribution is in good agreement with the measured temperature, while the calculated results by the traditional model had minor errors because the turbidity coefficient t_u is uncertainty. In addition, the vertical and transverse temperature gradient of a typical cross-section and the temperature distribution of the tower are also studied.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.17-24
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• 2010

태양열 제습냉방은 액체흡수제를 이용한 냉각효과로 기존의 전기에너지를 가능케 하는 해결책중 하나이다. 따라서 태양열을 거의 활용하지 않는 여름에 가열온수를 열원으로 활용하여 쾌적조건을 구현하는 본 연구의 대상인 태양열냉방시스템은 제습기와 재생기로 크게 이루어져 있다. 본 논문은 제습기의 유량 변화에 따른 열전달 및 물질전달의 변화를 실험과 이론적 해석으로 규명하고 있는데, 흐름의 양상은 병렬형과 대향류형을 대상으로 하고 있다. 실험결과와 이론해석이 비교적 잘 일치하였으며, 대향류형이 병렬형보다도 물질전달 면에서 유리하게 나타났으며, 입 출구의 엔탈피 차이에서도 크서 열전달에서도 우수한 것으로 나타났다. 또한 그 차이를 본 논문에서는 나타내었으며, 일정한 높이나 길이 이상에서는 항상 일정함을 알 수 있었다. 따라서 본 논문의 결과들은 제습기의 유동흐름을 통한 태양열냉방시스템 중 제습기의 설계 및 성능 향상에 도움을 줄 것이다.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.8-15
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• 2011

제습기의 역할은 태양열제습냉방시스템 요소 중에서도 매우 중요하다. 본 논문은 이러한 특성에 맞추어 제작된 장치를 갖고서 제습능력에 영향을 미치는 유량비를 바꾸어 실험한 결과이다. 실험은 크기가 $40m^3$인 항온항습실을 대상으로 이루어졌으며, 향류형 제습기의 수직 높이는 0.4m로 고정되었다. 또한 충진층은 액체흡수제와의 접촉면을 넓게하기 위하여 플라스틱 충진재로 채워져 있으며, 흡수제의 온도는 빠른 변화를 보기 위하여 $15^{\circ}C$로, 농도는 40%로 고정하였다. 액체흡수제의 유량과 습도가 높은 공기의 유량을 각각 3단계로 바꾸어 실험한 결과, 풍량이 높을수록 제습기 효과는 낮아졌으나, 전체적인 제습량에서는 많아졌다. 한편, 제습기에서 액체흡수제 유량이 많을수록 제습되는 수분량이 많아졌으나, 시간의 변화에 따라 제습되는 속도는 현저하게 낮아졌다. 따라서, 향후 실험에서는 유량의 변화 폭을 더욱 확대해서 많은 실험 결과를 확보하고, 이를 모델링화 하여 높은 정확도를 예측할 필요가 있다.

• Solar Energy
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• v.15 no.3
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• pp.59-73
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• 1995

The thermal analysis is accomplished with the route for the underground power transmission system which adopts the water pipe cooling with trough in tunnel. As a result, in case of a cooling system based on a refrigerator, the optimum condition for the flow rate of cooling water and the air velocity are calculated as the $2{\sim}3{\ell}/s/pipe$ and $1{\sim}2m/s/fan$, respectively. On the other hand, in case of cooling tower the optimum condition for them are calculated as the $2{\sim}3{\ell}/s/pipe$ and 6 m/s/fan, respectively. But the cooling system based on a cooling tower has the problem of enlarging the size of cooling fan and suppressing the labor of operator in tunnel. Therefore, to meet all the cooling conditions for a given cooling section, the cooling system based on a refrigerator is more acceptable.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.347-354
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• 2009

Experimental study on a cross-flow air-cooled plate heat exchanger (PHE) was performed. Two types of PHEs were manufactured either with single-wave plates or with double-wave plates in parallel. Cooling air flows through the PHEs in a crosswise direction against internal hot water. The heat exchanger aims to substitute open-loop cooling towers with closed-loop water circulation, which guarantees cleanliness and compactness. In this study, prototype single-wave and double-wave PHEs were designed and tested in a laboratory scale experiments. From the tests, the double-wave PHE shows approximately 50% enhanced heat transfer performance compared to the single-wave PHE. However, the double-wave PHE costs 30% additional pressure drop. For the commercialization, a wide channel design for air flow would be essential for performance and reliability.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.277-280
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• 2009

Wind monitoring system is an absolutely-required system for assessing a performance and fatigue load of the wind energy generator in an on-shore wind energy experimental research complex. It was implemented for the purpose of monitoring the wind information measured from a meteorological tower at the monitoring house and of utilizing the measured data for the performance assessment, by using the LabVIEW program. Then, by adding the performance assessment-related data acquired from the wind energy generator during the performance assessment and the data recorder for synchronizing the data of meteorological tower, the system was implemented. Because it transmitted the data by converting the output 'RS-232' of data logger which measures the wind condition into CAN protocol, the data error rate was minimized, This paper is intended to explain the developed wind data monitoring system.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.348-358
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• 2008

Unlike structures in the air, the vibration analysis of a submerged or floating structure such as offshore structures is possibly only when the fluid-structures is understood, as the whole or part of the structure is in contact with water. Through the comparision between the experimental result and the finite element analysis result for a simple cylindrical model, it was verified that an added mass effects on the cylindrical structure. Using the commercial FEA program ANSYS(v.11.0), underwater added mass was superposed on the mass matrix of the structure. A frequency response analysis of forced vibration in the frequency considered the dynamic load was also performed. It was proposed to find the several important modes of resonance peak for these fixed cylindrical type structures. Furthermore, it is expected that the analysis method and the data in this study can be applied to a dynamic structural design and dynamic performance evaluation for the ground and marine purpose of power generator by wind.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.3
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• pp.109-120
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• 2015

Spatial heterogeneous characteristics of solar radiation energy from Climate Change gives rise to energy imbalance in the general ecological system including water resources. This study is to estimate the $CO_2$ flux of South Korea using Terra MODIS image and to assess the reliability of MODIS data from the ground measured $CO_2$ flux by eddy covariance flux tower data at 3 locations (two at mixed forest area and one at rice paddy area). The MODIS Gross Primary Productivity (GPP) product (MOD17A2), 8-day composite at 1-km spatial resolution was adopted for the spatial $CO_2$ flux generation. The MOD17A2 data by noise like cloud and snow in a day were tried to fill by Inverse Distance Weighted (IDW) method from valid pixels and the damping effect of MOD17A2 data were corrected by Quality Control (QC) flag. The MODIS $CO_2$ flux was estimated as the sum of GPP and Re (ecosystem respiration) by Lloyd and Taylor method (1994). The determination coefficient ($R^2$) between MODIS $CO_2$ and flux tower $CO_2$ for 3 years (2011~2013) showed 0.55 and 0.60 in 2 mixed forests and 0.56 in rice paddy respectively. The $CO_2$ flux generally fluctuated showing minus values during summer rainy season (from July to August) and maintaining plus values for other periods. The MODIS $CO_2$ flux can be a useful information for extensive area, for example, as a reliable indicator on ecological circulation system.