• Solar Energy
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• v.17 no.3
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• pp.13-21
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• 1997

In this study, the theoretical equation of thermal storage efficiency was established to applied long term hot water storage system. The, effective thermal diffusivity and storage efficiency were, measured through the experiment to predict the degree of mixture in thermal storage tank. The effective thermal diffusivity was inversely preportional to the storage efficiency. The most effective storage efficiency was obtained under condition of low flow rate and using the perforated distributor.

• Journal of the Korean Solar Energy Society
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• v.29 no.6
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• pp.32-38
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• 2009

The effects of surface radiative properties on the radiant cooling of opaque surfaces under clear sky condition are studied. Two types of surfaces, one gray and the other selective, are compared. For the nighttime cooling, black surface gives the lowest plate temperature and on the other hand the ideal selective surface gives the highest temperature. The reverse is true when there is an insolation. Equivalent radiative heat transfer coefficient of radiant cooling without convection is about $1{\sim}7\;W/m^2-K$ for the range of values studied. The surface with black within the $6{\sim}13\;{\mu}m$ band else zero emissivity could be regarded as a black surface for the nighttime radiant cooling purposes. However, lower band limit of $4\;{\mu}m$ is preferred to $6\;{\mu}m$ for small insolation situations.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.100-106
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• 2010

The purpose of this study is to predict the effective sky temperature on Osan City during the summer. The north latitude, east longitude of Osan City is $37^{\circ}06'$ and $127^{\circ}02'$. The altitude from the sea level is 48m. Empirical relations of the effective sky temperature suggested by Duffie and Beckman are compared on clear days. For the effective sky temperature prediction, data measured by the Korea Meteorological Administration is used as an input to the Bliss model. Both Hottel and Krondratyev model are used to calculate the water vapor emissivity. The results using Hottel's model match well with the empirical relation proposed by Bliss. The results show maximum, minimum, and average values depending on water vapor emissivity model. The maximum deviation is about 10K and is due to total emissivity model.

• Journal of the Korean Solar Energy Society
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• v.28 no.3
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• pp.1-6
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• 2008

It is necessary to estimate empirical constants in order to predict the monthly mean daily global radiation on a horizontal surface in the developing areas for alternative energy. Therefore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for any areas over Korea by calculating the regression models taking into account latitude, percentage of possible sunshine, and cloud cover. Results clearly demonstrates the reliability of the single linear equation for the estimation of global radiation, which is proposed by using percentage of possible sunshine method. When compared with the measured values, the average annual deviation falls between -3.1 to +0.6%.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.21-27
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• 2003

The comparative performance of the WAsP in calculating the wind climate in complex terrain has been examined in order to test the predictability of the wind resource assessment computer code in our country. An analysis was carried out of predicted and experimental 10-min averaged wind data collected over 8 months at four monitoring sites in SongDang province, Jeju island, composed of sea, inland flat terrain, a high and a low slope craters. The comparisons show that the WAsP preditions give better agreement with experimental data by adjusting the roughness descriptions, the obstacle list.

• Journal of the Korean Solar Energy Society
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• v.34 no.1
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• pp.19-27
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• 2014

Exterior vertical illuminance is an important factor for lighting control. But, there are not many researches about the exterior illuminance on a vertical surface. In this study, we predicted the exterior illuminance on a vertical surface using vertical luminous efficacy. First, we calculated the vertical luminous efficacy according to the sky clearness category. And we performed the statistical analysis of the measured and the calculated illuminance with luminous efficacy. The MBE and RMSE of the predicted exterior illuminance were-1.2% and 15.5%, respectively. Second, the annual illuminance on a vertical surface calculated with the luminous efficacy and the short-term measured solar irradiance was suggested in this study.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.91-98
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• 2011

연료전지 차랑용에 있어서 공기 가습 및 감습의 중요성은 매우 크다. 특히 PEM(Proton Exchange Membrane)연료전지에서 수분평형은 총괄시스템성능에 큰 영향을 미치는 요소인데, 이에 관한 중요한 연구가 지금까지 광범위하게 수행되고 있다. 또한 차량과 같이 동적부하 연료전지를 활용하는 분야에 있어서, 전류의 흐름은 차량용 파워 부하에 크게 영향을 받는다. 따라서 전기적 흐름이 발생하면, 이에 따라 수분이 발생하게 되는데, 이러한 응축 수분은 예측이 되며, 수관리 시스템에서 이를 중요한 제어 기준으로 활용한다. 그러므로 적절한 제어방법을 선택하면 유입공기의 온도와 습도의 최적값을 얻을 수 있다. 따라서, 본 논문에서는 PEM 연료전지의 수관리를 위하여 수분전달 모델과 유전알고리즘(genetic algorithm)을 사용하는 제어방법에 초점을 두고 있다.

• Journal of the Korean Solar Energy Society
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• v.21 no.3
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• pp.51-60
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• 2001

A greenhouse equipped with latent heat storage system was built to obtain various thermal properties, such as greenhouse air temperature, soil surface temperature, energy flow in latent heat storage, etc., which could be used in validation of greenhouse numerical model to be developed in this study. This numerical model expressed with Newton-Raphson method was programed by C-language and utilized to simulate greenhouse thermal behavior. Greenhouse air temperature and soil surface temperature predicted by the greenhouse model developed in this study were very close to the measured data obtained through almost 3 years of experiment. Therefore, it is concluded that the greenhouse model developed and verified by measured data could be utilized for simulating various thermal behaviors of greenhouses equipped with latent heat storage system to be used for energy saving purposes.

• Journal of the Korean Solar Energy Society
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• v.21 no.1
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• pp.51-60
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• 2001

Underground space gives two benifits to us. First, it helps us to solve the land scarcity problem in urban city. Second it also helps us to manage the thermal properties of underground to keep cool in summer and warm in winter. How much it save energy depends on the ability to predict the exact temperature of the space. The purpose of this paper is to make a function predicting the temperature of underground space, analysing the 20 years measures of underground temperature kept in Korea Central Weather Burea.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.86-94
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• 2011

For accurate dayligh tsimulation, accurate exterior illuminance is necessary. But, Korea Meteorological Agency provides only the solar irradiance data. Thus, there is a need for the research on luminous efficacy. In this study, global horizontal irradiance, diffuse horizontal irradiance, global horizontal illuminance, and diffuse horizontal illuminance were measured to calculate the luminous efficacy in SEOUL. And, we evaluated the applicability of the Perez's model by comparing the measured data and calculated data. As a result, measured global luminous efficacy is 126(110~129)lm/W and diffuse luminous efficacy is 127(115~133)lm/W in Seoul. Perez's model was relatively accurate with 5% difference in the diffuse luminous efficacy. But, it can be predicted about 15% lower in the global luminous efficacy.