• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.1-7
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• 2018

The gases emitted from internal combustion engines using fossil fuels are causing many social problems, such as environmental pollution, global warming, and adverse health effects on the human body. In recent years, the demand for renewable energy has increased, and government policy support and research and development are also active. In the collecting part of a solar energy system, which is widely used at home, propylene glycol (PG) (anti-freeze), as a heating medium, is mixed with water at a fixed value of 50%, and the heat is transferred to the collecting part at subzero temperatures. On the other hand, when leakage occurs in the heat medium in the heat collecting part, supplemental water is supplied to the solar heat collecting part due to the characteristics of the solar heat system, so that the concentration of antifreeze in the replenishing water becomes low. As a result, the temperature of the solar heat collecting part is lowered resulting in a frost wave, which causes economic damage. The purpose of this study was to develop a device capable of controlling the antifreeze concentration automatically in response to a temperature drop to prevent freezing of the heat collecting part generated in the solar energy system. The electrical conductivity of the H2O component was larger than that of PG, and the resistance increased with decreasing temperature. The PG concentration control values of 40, 50, and 60% should be controlled through calibration with a PG concentration of 39.6, 50.7, and 60.1%.

• Advances in Energy Research
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• v.4 no.4
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• pp.299-323
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• 2016

Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around $120^{\circ}C$. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.52-52
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• 1995

The temporal and spatial distribution of atmospheric transmissivity and depletion rate of solar radiation are investigated, and are compared to the concentration of several components of air pollution. The length of the data span is 11 years from 1983 to 1993. The data of radiation and sunshine rate recorded at 20 meteorological standard stations were used, and in order to investigate a relationship between the depletion rate of solar radiation and air pollution, the concentration data of air pollution observed in Seoul, Pusan, Taegu, Taejon and Kwangju were compiled from 1991 to 1993. Regression coefficient a and b vary from 0.100 to 0.209, from 0.464 to 0.691, and their means are 0.163 and 0.533, respectively. Climatological atmospheric transmissivity is ranged from 0.68 to 0.83, and its mean is 0.75. Atmospheric transmissivity is relatively low in Pusan, Taejon, Kwangju and Inchon which have large population and are highly industrialized. However, that in Chinju, Mokpo, Cheju and Sosan appears to be large compared to the aforementioned stations. Insolation rate of clear days varies from 0.71 to 0.58, and its mean is 0.63. Insolation rate of Kangnung and Chinju are higher than those of Seoul and Pusan by 5%. From the correlation coefficients between depletion rate of solar radiation and air pollution concentration, the most significant factors related to the depletion rate of solar radiation is appeared to be TSP followed by $SO_2$. Ozone shows a negative correlation, End $NO_2$ does not show a obvious correlation with the depletion rate of solar radiation.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.437-446
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• 1995

The temporal and spatial distribution of atmospheric transmissivity and depletion rate of solar radiation are investigated, and are compared to the concentration of several components of air pollution. The length of the data span is 11 years from 1983 to 1993. The data of radiation and sunshine rate recorded at 20 meteorological standard stations were used, and in order to investigate a relationship between the depletion rate of solar radiation and air pollution, the concentration data of air pollution observed in Seoul, Pusan, Taegu, Taejon and Kwangju were compiled from 1991 to 1993. Regression coefficient a and b vary from 0.100 to 0.209, from 0.464 to 0.691, and their means are 0.163 and 0.533, respectively. Climatological atmospheric transmissivity is ranged from 0.68 to 0.83, and its mean is 0.75. Atmospheric transmissivity is relatively low in Pusan, Taejon, Kwangju and Inchon which have large population and are highly industrialized. However, that in Chinju, Mokpo, Cheju and Sosan appears to be large compared to the aforementioned stations. Insolation rate of clear days varies from 0.71 to 0.58, and its mean is 0.63. Insolation rate of Kangnung and Chinju are higher than those of Seoul and Pusan by 5%. From the correlation coefficients between depletion rate of solar radiation and air pollution concentration, the most significant factors related to the depletion rate of solar radiation is appeared to be TSP followed by $SO_2$. Ozone shows a negative correlation, End $NO_2$ does not show a obvious correlation with the depletion rate of solar radiation.

• Ocean and Polar Research
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• v.40 no.4
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• pp.281-288
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• 2018

The transmission of solar light according to the distribution of chromophoric dissolved organic matter (CDOM) was measured in the Pacific Arctic Ocean. The Research Vessel Araon visited the ice-covered East Siberian and Chukchi Seas in August 2016. In the Arctic, solar [ultraviolet-A (UV-A), ultraviolet-B (UV-B), and photosynthetically active radiation (PAR)] radiation reaching the surface of the ocean is primarily protected by the distribution of sea ice. The transmission of solar light in the ocean is controlled by sea ice and dissolved organic matter, such as CDOM. The concentration of CDOM is the major factor controlling the penetration depth of UV radiation into the ocean. The relative CDOM concentration of surface sea water was higher in the East Siberian Sea than in the Chukchi Sea. Due to the distribution of CDOM, the penetration depth of solar light in the East Siberian Sea (UV-B, $9{\pm}2m$; UV-A, $13{\pm}2m$; PAR, $36{\pm}4m$) was lower than in the Chukchi Sea (UV-B, $15{\pm}3m$; UV-A, $22{\pm}3m$; PAR, $49{\pm}3m$). Accelerated global warming and the rapid decrease of sea ice in the Arctic have resulted in marine organisms being exposed to increased harmful UV radiation. With changes in sea ice covered areas and concentrations of dissolved organic matter in the Arctic Ocean, marine ecosystems that consist of a variety of species from primary producers to high-trophic-level organisms will be directly or indirectly affected by solar UV radiation.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.545-554
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• 1999

We would like to develop a short-term model to predict the time-related concentration of ozone whose reaction mechanism is complex. The paper targets Seoul where an ozone alert system has recently been employed. In order to develop a short-term prediction model for ozone, we suggested the Ozone Peak Indicator(OPI), an equivalent of the potential daily maximum ozone concentration, with precursors being the only limiting factor, and we calculated the Ozone Peak Indicarot as OPI={$rac{(O_3)_{max}cdot(H_{eH})_{max}(Rad)_{max}$ to preclude the influence of mixing height and solar radiation on the daily maximum ozone concentration. The OPI on the day of the prediction is to be calcultated by using the relation between OPI and the initial value of precursors. The basic prediction formula for time-related ozone concentration was established as $O_3(1)={(OPI)cdot Rad(t-2)H_{eH}}$, using the OPI, solar radiation two hours before prediction and mixing height. We developed, along with the basic formula for predicting photochemical oxidants, "SEOM"(Seoul Empirical Oxidants Model), a Fortran program that helps predict solar radiation and mixing height needed in the prediction of ozone pollution. When this model was applied to Seoul and an analysis of the correlation between the observed and the predicted ozone concentrations was made through SEOM, there appeared a very high correlation, with a coefficient of 0.815. SEOM can be described as a short-term prediction model for ozone concentration in large cities that takes into account the initial values of precursors, and changes in solar radiation and mixing height. SEOM can reflect the local characteristics of a particular and region can yield relatively good prediction results by a simple data input process.t process.

• Solar Energy
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• v.6 no.2
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• pp.15-21
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• 1986

In this study, an experimental double diffusive thermohaline system heated from below was constructed and the phenomena of each layer developed in the system were observed. The experiment was performed with the initial salt concentration gradient of $-436.2kg/m^4$ and the net heat flux of approximately $176w/m^2$. An electroconductivity-temperature probe was made and used for the measurements of salt concentration. As the result of this study, it was found that the salt concentration decreased in the bottom mixed layer and increased in the top mixed layer during the experiment while the salt concentration gradient in the diffusive layer unchanged. It was also found that the interfacial boundary layers were due largely to variations in salt concentration rather than temperature.

• Journal of Environmental Science International
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• v.23 no.7
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• pp.1241-1251
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• 2014

The study investigates weekday/weekend characteristics of $PM_{10}$ and $PM_{2.5}$ concentrations and meteorological elements in Busan. The $PM_{10}$ concentration is highest on Wednesday and Thursday, and lowest on Sunday. On the other hand, the $PM_{2.5}$ concentration is highest on Wednesday and lowest on Sunday. The location where concentrations of weekdays and weekend differ the most is Hwakjang-dong, the industrial area, and where they differ the least is Gijang-up and Joa-dong, the residential area. Fine particle concentration in the industrial area was consistent at dawn and in the morning, but varied in the afternoon and at night. The visibility of Sunday was 0.49 km higher than that of weekdays, and the solar radiation of Sunday was $0.11MJ/m^2$ higher than that of weekdays. These results indicate that the concentration of fine particles had influence on the change of visibility and solar radiation.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.47-59
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• 2011

The purpose of this paper is to simulate the high ozone concentration in Shiwha Banwol indusrial complex. High pollution episodes (ozone alert) of this area are the results of geographical location and its air pollutants emission. This research has used meteorological model (RAMS) and photochemical air pollution Model (CIT model). As first step of the evaluate of this combined model system simulations are done in terms of meteorological characteristics like wind fields, PBL-height, etc.. Numerical simulations are carried out with real meteorological synoptic data on June. 24-25, 2010. In comparison with real measurement and another research the model reflects well local meteorological phenomena and shows the possibility to be utilized to analyse the pollutant dispersion over irregular terrain region. The high ozone concentration is deeply correlated to the ambient air temperature, wind speed and solar radiation. Local meteorological phenomena like sea-land breeze impact on horizontal dispersion of ozone. This analysis of meteorological characteristics can, in turn, help to predict their influences on air quality and to manage the high ozone episodes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.293-297
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• 2010

Next generation concentrating photovoltaic technologies could have a large-scale impact on world electricity production once they will become economically attractive and grid parity will be reached. Multi-junction solar cells will be characterised by a high value of the cell economical performance index if the cells were able to operate at high concentration level. Concentrating the sunlight by optical devices like lenses or mirrors reduces the area of expensive solar cells or modules, and, moreover, increases their efficiency. Accurate and reliable tracking is an important issue to maintain high the CPV system output power. Further, for high concentration CPV systems, the actual tracker cost is about 20% of the total CPV system cost. In this paper high-concentration is defined as systems using concentration ratios well above 100 times the one sun intensity and trackerlss CPV system studied. Using sphericalness lens and parallel MJ cell connection method were suggested and achieved experiment on a clear day in summer. Development of these high performance multi-junction CPV module promises to accelerate growth in photovoltaic power generation.