• Journal of Nutrition and Health
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• v.29 no.9
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• pp.1003-1012
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• 1996

We examined the relationship among riboflavin intake, work activity, erythrocyte glutathione reductase activity coefficient(EGR AC)and urinary riboflavin excretion. We also attempted to determine factors affecting seasonal riboflavin status of rural women. All information about nutrient intake, work activity and riboflavin biochemical status was repeatly collected in three seasons ; farming season(June), harvest season(October), nonfarming season(February). EGR AC was negatively correlated with riboflavin intake(P<0.005) and positively correlated with the duration(min) of farming activity(P<0.005) and the percentage of lean body mass(LBM) (%) representing long term physical activity(P<0.05) in harvestseason. Urinary riboflavin excretion was positively correlated with the ratio of riboflavin intake to 1,000kcal of energy expenditure (P<0.05) in farming season and negatively correlated with the duration(min) of farming activity (P<0.05) and crude nitrogen balance(P<0.005) in harvest season. It appeared that EGR AC seems to increase and urinary riboflavin excretion seems to decrease as work activity increase. Therefore work activity would be expected to deteriorate riboflavin status. Multiple regression analysis of variables showed that in general EGR AC was affected by riboflavin and energy intakes, energy expenditure, energy balance, the duration(min) of farming activity, LBM (%). Urinary riboflavin excretion was affected by riboflavin and protein intakes, LBM(kg) and crude nitrogen balance. Crude nitrogen balance affected urinary riboflavin excretion in all seasons. The result indicated that work activity as well as nutrient intake seemed to affect riboflavin status, especially EGR AC was affected preferentially be work activity in all seasons.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.28-34
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• 2019

Solar energy is one of the most abundant renewable energy sources on Earth but there are restrictions on the use of solar thermal energy due to the time-discrepancy between the solar-rich season and heating demand. In Europe and Canada, a seasonal solar thermal energy storage (SSTES), which stores the abundant solar heat in the summer and uses the heat for the winter heating load, is used. Recently, SSTES has been introduced in Korea and empirical studies are actively underway. In this study, a $2,000m^2$ flat plate type solar collector and $20,000m^2$ of borehole thermal energy storage (BTES) were studied for a greenhouse in Hwaseong City, which has a heating load of 2,164 GJ/year. To predict the dynamic performance of the system over time, it was simulated using the TRNSYS 18 program, and the solar fraction of the system with the control conditions was investigated. As a result, the solar BTES system proposed in this study showed an average solar fraction of approximately 60% for 5 years when differential temperature control was applied to both collecting solar thermal energy and discharging BTES. The proposed system simplified the configuration and control method of the solar BTES system and secured its performance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1215-1220
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• 1997

This study was undertaken to estimate heath status, meal management, and seasonal variation of nutrient intake of rural women. The study was carried out in three seasons ; farming season(June), harvest season(October), nonfarming season(February). General characteristics, health status, and meal management of subjects were assessed using questionnaire and interview. Nutrient intake was measured by 24hr recall. Only 39.5% of subjects felt healthy. 21.1% of subjects often skipped meal each day. In farming & harvest seasons 92.1% of subjects participated in agriculture but 78.9% of subjects had the same or less appetite and 63.2% of subjects ate the same or less than usual. The mean intakes of energy and riboflavin in all seasons, calcium in June & February, and protein, vitamin A, and thiamin in February were below Recommended Dietary Allowances(RDA) for Koreans. All nutrient intake was significantly low in February but was not significantly different between in June and October.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.183-183
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• 2017

Pan evaporation (Epan) is an important indicator of water and energy balance. Despite global warming, decreasing annual Epan has been reported across different continents over last decades, which is claimed as pan evaporation paradox. However, such trend is not necessarily found in seasonal data because the level of contributions on Epan vary among meteorological components. This study investigates long-term trend in seasonal pan evaporation from 1908 to 2016 across South Korea. Meteorological variables including air temperature (Tair), wind speed (U), vapor pressure deficit (VPD), and solar radiation (Rs) are selected to quantify the effects of individual contributing factor to Epan. We found overall decreasing trend in Epan, which agrees with earlier studies. However, mixed tendencies between seasons due to variation of dominant factor contributing Epan were found. We also evaluated the reference evapotranspiration based on Penman-Monteith method and compared this with Epan to better understand the physics behind the evaporation paradox.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.192-198
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• 2014

To establish the design criteria for seasonal heating load calculation in greenhouses, standard weather data are required. However, they are being provided only at seven regions in Korea. So, instead of using standard weather data, in order to find the method to build design weather data for seasonal heating load calculation, heating degree-hour and heating degree-day were analyzed and compared by methods of fundamental equation, Mihara's equation and modified Mihara's equation using normal and thirty years from 1981 to 2010 hourly weather data provided by KMA and standard weather data provided by KSES. Average heating degree-hours calculated by fundamental equation using thirty years hourly weather data showed a good agreement with them using standard weather data. The 24 times of heating degree-day showed relatively big differences with heating degree-hour at the low setting temperature. Therefore, the heating degree-hour was considered more appropriate method to estimate the seasonal heating load. And to conclude, in regions which are not available standard weather data, we suggest that design weather data should be analyzed using thirty years hourly weather data. Average of heating degree-hours derived from every year hourly weather data during the whole period can be established as environmental design standards, and also minimum and maximum of them can be used as reference data for energy estimation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.3
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• pp.63-71
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• 2003

This study investigated about the seasonal variation of pollutant loads flowing into the Yeong-il bay from constructing Tank model which is the simulation model to evaluate the daily river discharge and pollutant load in the Hyeong-san river watershed. The estimated annual average river discharge of Hyeong-san river flowing into Yeong-il bay is about 878.34×10/sup 6/㎥/year which is about 73% of annual average of total precipitation in Hyeong-san river watershed. The annual average of pollutant load flowing into Yeong-il bay was estimated each 15.11 ton-COD/year, 23.24 ton-SS/year, 10.65 ton-TN/year, and 0.54 ton-Tp/year. For the seasonal variation of pollutant loads, it was tended as increasing of river discharge as increasing of inflow pollutant loads at June and July of summer and October of autumn. The main source of pollutant loads was found to be the Pohang city and Pohang industrial complex which are located near the mouth of Hyeong-san river. Therefore, for effective water quality management of Yeong-il bay, the counterplan to reduce pollutant loads from the main source of pollutant loads is required.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.8-15
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• 2004

Wave power distribution is investigated to determine the optimal sites for wave power generation at Jeju sea which has the highest wave energy density in the Korean coastal waters. The spatial and seasonal variation of wave power per unit length is calculated in the Jeju sea area based on the monthly mean wave data from 1979 to 2002 which is produced by the SWAN wave model simulation in prior research. The selected favorable locations for wave power generation are compared in terms of magnitude of wave energy density and distribution characteristics of wave parameters. The results suggest that Chagui-Do is the most optimal site for wave power generation in the Jeju sea. The seasonal distribution of wave energy density reveals that the highest wave energy density occurs in the northwest sea in the winter and it is dominated by wind waves, while the second highest one happens at south sea in the summer and it is dominated by a swell sea. The annual average of wave energy density shows that it gradually increases from east to west of the Jeju sea. At Chagui-Do, the energy density of the sea swell sea is relatively uniform while the energy density of the wind waves is variable and strong in the winter.

• Journal of the Korean Solar Energy Society
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• v.39 no.3
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• pp.59-66
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• 2019

New and renewable energy forecasts are key technology to reduce the annual operating cost of new and renewable facilities, and accuracy of forecasts is paramount. In this study, we intend to build a model for the prediction of short-term solar power generation for 1 hour to 3 hours. To this end, this study applied two time series technique, ARIMA model without considering seasonality and SARIMA model with considering seasonality, comparing which technique has better predictive accuracy. Comparing predicted errors by MAE measures of solar power generation for 1 hour to 3 hours at four locations, the solar power forecast model using ARIMA was better in terms of predictive accuracy than the solar power forecast model using SARIMA. On the other hand, a comparison of predicted error by RMSE measures resulted in a solar power forecast model using SARIMA being better in terms of predictive accuracy than a solar power forecast model using ARIMA.

• Proceedings of the KSEEG Conference
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• 2000.04b
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• pp.247-248
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• 2000

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.3 no.2
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• pp.39-51
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• 2007

Unconsolidated and permeable alluvial deposit composed of sand and gravel is distributed along the fluvial plain at the Iryong study area. Previous studies on the area show that a single alluvial well can produce at least 1,650m3d-1 of bank infilterated shallow groundwater(BIGW) from the deposit. This study is aimed to evaluate and simulate the influence that seasonal variation of water levels and temperatures of the river have an effect on those of BIGW under the pumping condition and also to compare seasonal variation of COPs when indirectly pumped BIGW or directly pumped surface water are used for a water to water heat pump system as an heat source and sink using 3 D flow and heat transport model of Feflow. The result shows that the magnitude influenced to water level of BIGW by fluctuation of river water level in summer and winter is about 48% and 75% of Nakdong river water level separately. Seasonal change of river water temperature is about $23.7^{\circ}C$, on other hand that of BIGW is only $3.8^{\circ}C$. The seasonal temperatures of BIGW are ranged from minimum $14.5^{\circ}C$ in cold winter(January) and maximum $18.3^{\circ}C$ in hot summer(July). It stands for that BIGW is a good source of heat energy for heating and cooling system owing to maintaining quite similar temperature($16^{\circ}C$) of background shallow groundwater. Average COPh in winter time and COPc in summer time of BIGW and surface water are estimated about 3.95, 3.5, and about 6.16 and 4.81 respectively. It clearly indicates that coefficient of performance of heat pump system using BIGW are higher than 12.9% in winter time and 28.1% in summer time in comparision with those of surface water.