• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.6
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• pp.696-707
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• 1988

This study simulates a typical solar system using the transient simulation program TRNSYS, and calculates the maximum cooling load of the model room of $50m^2$. In this study, energy rate control method is used in calculating a maximum cooling load. On the ground of the maximum cooling load of the model room, the variables that have an effect on the solar collection performance of the solar system are made a selection. Also in this study the trend of the solar collection performance is shown as the variables change. The results show that the variables which have an effect on the collection performance are collector area, collector mass flow rate, collector slope and the volume of storage tank, and the optimal value of Ac/Vt is not constant but varies as the collector area and the collector mass flow rate. Also the results show that for cooling system the optimal value of the collector slope is latitude minus $15^{\circ}$ during the seasonal operations, and twenty percent of the maximum cooling load is saved with the aid of the solar energy.

• Journal of Ginseng Research
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• v.32 no.4
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• pp.347-356
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• 2008

Forest-grown American ginseng (Panax quinquefolius L.) is exposed to daily and seasonal light variations. Our goal was to determine the effect of understory light changes on the maximum quantum yield of photosystem II, expressed as $F_v/F_m$, and photosynthetic pigment composition of two-year-old plants. Understory light photon flux density and sunfleck durations were characterized using hemispherical canopy photography. Our results showed that understory light significantly affected the $F_v/F_m$ of American ginseng, especially during the initial development of the plants when light levels were the highest, averaging 28 mol $m^{-2}d^{-1}$. Associated with low $F_v/F_m$ during its initial development, American ginseng had the lowest levels of epoxidation state of the xanthophyll cycle of the season, suggesting an active dissipation of excess light energy absorbed by the chlorophyll pigments. As photon flux density decreased after the deployment of the forest canopy to less than 10 mol $m^{-2}d^{-1}$, chlorophyll a/b decreased suggesting a greater investment in light harvesting pigments to reaction centers in order to absorb the fleeting light energy.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.89-95
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• 1998

Maintenance scheduling of generators plays an important role in evaluating supply reliability of power systems. Since generators must be maintained and inspected, the generation planner must schedule planned outages during the year. Several factors entering into this scheduling analysis include: seasonal load-demand profile, amount of maintenance, size of the units, elapsed time from last maintenance, and availability of maintenance crew. This paper proposes a new maintenance scheduling algorithm for the alternatives of long-term generation expansion planning by using LOLP levelization method which is known as an effective method for the generator's maintenance scheduling. To get the best supply reliability of power systems, we change the maintenance period to levelize the reliability over all period. The proposed algorithm is applied to a real size power system and the better reliability results are obtained.

• New & Renewable Energy
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• v.3 no.3
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• pp.28-35
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• 2007

In this study, the wave power resources at the three locations [Sokcho, Hupo, and Onsan] on the east coast of Korea were estimated by using the field measurement data and were compared with the results of previous researches. It was found that seasonal variation of the wave power is very significant on the east coast of Korean peninsula. The wave power was the smallest in the summer season at all the locations. At Hupo and Onsan, the highest value of the monthly-averaged wave power was observed in September, probably because the pathways of typhoon in September were close to both locations. At the northest location, Sockcho, in contrast, the monthly highest value of the wave power appeared in January, probably owing to the influence of storm waves driven by Donghae twister. The estimated annual average wave power was 4.5 kW/m at Sokcho, which was about two times larger than those at other two locations. It is noteworthy that this result is completely different from past researches based on wave hindcasting data. In addition, the estimates of wave power by the past researches seemed to be smaller than those of the present study, especially at the northern region of the east coast.

• Atmosphere
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• v.30 no.1
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• pp.59-73
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• 2020

The characteristics of solar resources in South Korea were analyzed by comparing the solar irradiance derived from COMS (Communication, Ocean and Meteorological Satellite) with in-situ ground observation data (Pyranometer). Satellite-derived solar irradiance and in-situ observation showed general coincidence with correlation coefficient higher than 0.9, but the satellite observations tended to overestimate the radiation amount compared to the ground observations. Analysis of hourly and monthly irradiance showed that relatively large discrepancies between the satellite and ground observations exist after sunrise and during July~August period which were mainly attributed to uncertainties in the satellite retrieval such as large atmospheric optical thickness and cloud amount. But differences between the two observations did not show distinct diurnal or seasonal cycles. Analysis of regional characteristics of solar irradiance showed that differences between satellite and in-situ observations are relatively large in metrocity such as Seoul and coastal regions due to air pollution and sea salt aerosols which act to increase the uncertainty in the satellite retrieval. It was concluded that the satellite irradiance data can be used for assessment and prediction of solar energy resources overcoming the limitation of ground observations, although it still has various sources of uncertainty.

• Journal of the Korean Solar Energy Society
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• v.29 no.3
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• pp.45-50
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• 2009

To estimate the operating performances of the geothermal heat exchange pipe(GHEX), GHEXs of 400RT geothermal system were measured and analyzed through a year. The followings are the results. The temperature of 2 GHEXs installed 4m apart was fluctuated very similarly. When the geothermal system is nor operating or is operating as heating mode, the temperature of G.L.-170m was always higher than G.L.-70m's. But it reversed when the geothermal system is operating as cooling mode. And through a year, it has been observed that the temperature of G.L.-170m is increased approximately $1.5^{\circ}C$. With previously mentioned results, the heat transfer capacity of G.L.-70m's geological stratum is estimated as higher than that of the G.L.-170m.

• Advances in Energy Research
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• v.6 no.2
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• pp.131-143
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• 2019

Global Solar Radiation (GSR) is the key element for performance estimation of any Solar Power Plant (SPP). Its forecasting may help in estimation of power production from a SPP well in advance, and may also render help in optimal use of this power. Seasonal Auto-Regressive Moving Average (SARMA) and Artificial Neural Network (ANN) models are combined in order to develop a hybrid model (SARMA-ANN) conceiving the characteristics of both linear and non-linear prediction models. This developed model has been used for prediction of GSR at Gorakhpur, situated in the northern region of India. The proposed model is beneficial for the univariate forecasting. Along with this model, we have also used Auto-Regressive Moving Average (ARMA), SARMA, ANN based models for 1 - 6 day-ahead forecasting of GSR on hourly basis. It has been found that the proposed model presents least RMSE (Root Mean Square Error) and produces best forecasting results among all the models considered in the present study. As an application, the comparison between the forecasted one and the energy produced by the grid connected PV plant installed on the parking stands of the University shows the superiority of the proposed model.

• Journal of the Korean Solar Energy Society
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• v.24 no.3
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• pp.65-71
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• 2004

This study analysed data on the weather of Seoul, Gwangju and Mokpo to examine the degree of temperature increase in those Korean cities. 1) When the results of the analysis were compared with those of previously analysed temperature increase in 1990s and 1940s, there was an increase in temperature of $1.7^{\circ}C$ in Seoul, $1.5^{\circ}C$ in Gwangju and $0.7^{\circ}C$ in Mokpo. 2) According to the seasonal analysis, $1.7^{\circ}C$ in Seoul, $1.5^{\circ}C$ in Gwangju and $0.7^{\circ}C$ in Mokpo increased in Spring. On a monthly basis in Spring increase in April was highest($2.3^{\circ}C$ and $1.0^{\circ}C$ in Gwangju and Mokpo, respectively). As for Seoul, $2.4^{\circ}C$ increased in March, highest. In July and August of Summer, no significant change occurred in the three cities, but in Autumn, $1.0^{\circ}C,\;1.5^{\circ}C$, and $0.3^{\circ}C$ in Seoul, Gwangju and Mokpo increased, respectively. In Winter, $2.9^{\circ}C$ in Seoul, $1.9^{\circ}C$ in Gwangju, and $2.3^{\circ}C$ in Mokpo increased, respectively.

• Journal of Environmental Science International
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• v.11 no.10
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• pp.1045-1054
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• 2002

Urban atmospheric conditions are usually settled as warmer, drier and dirtier than those of rural counterpart owing to reduction of green space and water space area heat retention in surfaces such as concrete and asphalt, and abundant fuel consumption. The characteristics of urban climate has become generally known as urban heat island. The purpose of this study is to investigate the temporal and spatial distribution of the heat emission from human activity, which is a main factor causing urban heat island. In this study, the anthropogenic heat fluxes emitted from vehicles and constructions are estimated by computational grid mesh which is divided by 1km $\times$ 1km. The anthropogenic heat flux by grid mesh can be applied to a numerical simulation model of the local circulation model. The constructions are classified into 9 energy-consumption types - hospital, hotel, office, department store, commercial store, school, factory, detached house and flat. The vehicles classified into 4 energy-consumption types - car, taxi, truck and bus. The seasonal mean of anthropogenic heat flux around central Daegu exceeded $50 W/m^2$ in winter. The annual mean anthropogenic heat flux exceeded $20 W/m^2$. The values are nearly equivalent to the anthropogenic heat flux in the suburbs of Tokyo, Japan.

• Development and Reproduction
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• v.14 no.3
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• pp.185-197
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• 2010

The reproduction of animals is a means to maintain their species. The golden hamsters are seasonal breeders, and their reproduction is regulated by the photoperiod. The shifts of the sexual functions imply the changes of the protein expression, and those are reflected by the proteome. Thus the present study was to examine via two dimensional polyacrylamide gel electrophoresis (2d PAGE), the physiological changes and the alterations of protein expressions in hypothalamus upon the reproductive situation related to the pineal gland. Among the pineal intact animals, the reproductive functions were sustained in animals housed in long photoperiod (LP) but regressed in animals housed in short photoperiod. And those pinealectomized animals showed high sexual activities regardless of photoperiod. Ultimately they were branched into dichotomy, sexually active and inactive animals. Apart from the changes of physiological parameters upon the reproductive conditions, there were obvious differences in proteins extracted from the hypothalamus. The hypothalamus of LP animals presented high levels of enzymes which are involved in the production of energy, glycolysis and Krebs cycle. The increased energy might be related to the GnRH synthesis in hypothalamus and indirectly to the constant cell divisions in spermatogenesis. Taken together, the impacts of the photoperiodic information controlling reproduction could be observed through 2d PAGE. Therefore, the present results suggest the potential of biomarkers collectively to diagnose the fertility and the infertility by way of proteomics in organs with regard to the reproductive system, further could be applied to diagnose various diseases.