• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.56 no.2
• /
• pp.159-166
• /
• 2011

This experiment was carried out to evaluate the effects of top dressing of nitrogen and harvest time on the growth, feed value and anthocyanin content for developing functional feed of colored barley. A colored barley cultivar, Boanchalbori, was tested in this experiment. Top dressing was applied at seven separate growth stages, regeneration time (RT), and intervals of 20, 30, 40, 50, 60, and 70 days after RT, and harvested at different time from 20 days after heading (DAH) to 40 DAH with 10 days interval in split plot design with three replications. Plant height was increasing with earlier top dressing, but not affected by harvest time. Percent dry matter was increasing with earlier top dressing and later harvests. Protein content was increased with later top dressing and harvests, but percent NDF, ADF and TDN was not significant. Total anthocyanin content was increased with earlier top dressing, included increasing C3G (cyanidin-3-glucoside) and delphinidin. The C3G and delphinidin were detected from 25 DAH and P3G (pelargonidin-3-g1ucoside), cyanidin and perlagonidin from 30 DAH. Their contents were increased significantly as harvest was delayed. This experiment provides some interesting results with respects to optimum top dressing and harvest time for the functional feed production of the colored barley.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.3
• /
• pp.64-81
• /
• 2016

To analyze the influence of various groundwater flow rates (specific discharge) on BHE system with balanced and unbalanced energy loads under assuming same initial temperature (15℃) of ground and groundwater, numerical modeling using FEFLOW was used for this study. When groundwater flow is increased from 1 × 10⁻⁷ to 4 × 10⁻⁷m/s under balanced energy load, the performance of BHE system is improved about 26.7% in summer and 22.7% at winter time in a single BHE case as well as about 12.0~18.6% in summer and 7.6~8.7% in winter time depending on the number of boreholes in the grid, their array type, and bore hole separation in multiple BHE system case. In other words, the performance of BHE system is improved due to lower avT in summer and higher avT in winter time when groundwater flow becomes larger. On the contrary it is decreased owing to higher avT in summer and lower avT in winter time when the numbers of BHEs in an array are increased, Geothermal plume created at down-gradient area by groundwater flow is relatively small in balanced load condition while quite large in unbalanced load condition. Groundwater flow enhances in general the thermal efficiency by transferring heat away from the BHEs. Therefore it is highly required to obtain and to use adequate informations on hydrogeologic characterristics (K, S, hydraulic gradient, seasonal variation of groundwater temperature and water level) along with integrating groundwater flow and also hydrogeothermal properties (thermal conductivity, seasonal variation of ground temperatures etc.) of the relevant area for achieving the optimal design of BHE system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.9
• /
• pp.355-360
• /
• 2016

Continuing to the modeling of heating load, this paper, as the second part of consecutive works, presents LS-SVM (least square support vector machine) based model of winter time apartment hot water supply load in a district heating system, so as to be used in prediction of heating energy usage. Similar, but more severely, to heating load, hot water supply load varies in highly nonlinear manner. Such nonlinearity makes analytical model of it hardly exist in the literatures. LS-SVM is known as a good modeling tool for the system, especially for the nonlinear system depended by many independent factors. We collect 26,208 data of hot water supply load over a 13-week period in winter time, from 12 heat exchangers in seven different apartments. Then part of the collected data were used to construct LS-SVM based model and the rest of those were used to test the formed model accuracy. In modeling, we first constructed the model of district heating system's hot water supply load, using the unit heating area's hot water supply load of seven apartments. Such model will be used to estimate the total hot water supply load of which the district heating system needs to provide. Then the individual apartment hot water supply load model is also formed, which can be used to predict and to control the energy consumption of the individual apartment. The results obtained show that the total hot water supply load, which will be provided by the district heating system in winter time, can be predicted within 10% in MAPE (mean absolute percentage error). Also the individual apartment models can predict the individual apartment energy consumption for hot water supply load within 10% ~ 20% in MAPE.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.372-372
• /
• 2021

The agriculture sector plays a vital role in the economy of Pakistan by contributing about 20% of the GDP and 42% of the labor force. Rivers from the top of Himalayas are the major water resources for this agriculture sector. Recent reports have found that Pakistan is one of the most vulnerable country to climate change that can cause water scarcity which is a big challenge to the communities. Previous studies have investigated the impact of climate change on the trend of streamflow, but the understanding of seasonal change in the regional hydrologic regimes remained limited. Therefore, a better understanding of the seasonal hydrologic change will help cope with the future water scarcity issue. In this study, we used the daily stream flow data for four major river basins of Pakistan (Chenab, Indus, Jhelum and Kabul) over 1962 - 2019. Utilizing these daily river discharge data, we calculated the winter-spring center time and the summer-autumn center times. In this study Winter-spring center time (WSCT) is defined as the day of the calendar year during which half of the total six months (Jan-Jun) discharge volume was exceeded. Results show that the four river basins experienced a statistically significant decreasing trend of WSCT, that is the center time keeps coming earlier compared to the past. We further used the Climate Research Unit (CRU) climate data comprising of the average temperature and precipitation for the four basins and found that the increasing average temperature value causes the early melting of the snow covers and glaciers that resulted in the decreasing of 1^st center time value by 4 to 8 days. The findings of this study informs an alarming situation for the agriculture sector specifically.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2001.11a
• /
• pp.76-81
• /
• 2001

Recently, the structure is higher and larger, so that the application of high-strength concrete is increased, And as the development of construction skills, it is possible to place during the winter. Concrete work during winter is indispensible to shorten time of completion and cut costs. When concrete work during winter is placed, it has anxiety that concrete freeze at low temperature. As repetition of concrete's freezing cause reduction of durability, it is necessary for mixing to pay attention to air content and W/C ratios. Accordingly, in this study, we estimate the frost resistance by air content and W/C ratios, and development of strength after early-frost damage in the high-strength concrete during the cold weather. In this study, it could be confirmed that factors which were air content, W/C ratios and early curing period, affected on the frost resistance.

• KDI Journal of Economic Policy
• /
• v.41 no.1
• /
• pp.43-58
• /
• 2019

Since 2009, electricity consumption has developed a unique seasonal pattern in South Korea. Winter loads have sharply increased, and they eventually exceeded summer peaks. This trend reversal distinguishes these load patterns from those in the USA and the EU, where annual peaks are observed during the summer months. Using Levene's test, we show statistical evidence of a rise in temperature but a decrease in variance over time regardless of the season. Despite the overall increase in the temperature, regardless of the season there should be another cause of the increased demand for electricity in winter. With the present study using data from 1991 to 2012, we provide empirical evidence that relatively low electricity prices regulated by the government have contributed significantly to the rapid upward change in electricity consumption, specifically during the winter months in the commercial sector in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.45 no.4
• /
• pp.272-275
• /
• 2000

Winter green manure crops including legume increase grain yield of subsequent crop and substitute N fertilizer requirement with organic-No Hairy vetch grows vigorously and can provide N-rich green manure for corn with its soil incorporation after wintering. But, grain yield of corn as succeeding crop would be reduced if its planting time is delayed until late spring. This experiment was carried out to find the proper incorporation time of hairy vetch green manure and planting time of subsequent corn in cropping system with winter hairy vetch(green manure)-summer corn. Hairy vetch was incorporated into soil at a ten-day interval between April 10 and May 10 and corn was planted at 5 days after each hairy vetch incorporation. Soil nitrate concentration on April 10 and 20 in hairy vetch plot was slightly lower than that at winter fallow. Above-ground dry matter and organic-N of hairy vetch increased linearly with delayed hairy vetch incorporation time from April 10 to May 10. Average dry matter and organic-N produced by hairy vetch were 5.7 ton/ha and 248 kgN/ha, respectively. Corn growth and yield decreased as delayed corn planting time after May in spite of increasing dry matter and N-yield of hairy vetch. Nitrogen concentration of corn grain, stalk and whole plant at harvest were the highest in May 5 planting, but total N-uptake of May 5 planting were not different from that of April 25 planting because of lower grain yield. It was concluded that the proper incorporation time of hairy vetch and corn planting time were April 20 and April 25, respectively, because grain yield was the highest and corn could use hairy vetch-N effectively to produce dry matter.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.10 no.2
• /
• pp.58-64
• /
• 2008

This study was carried out to determine the availability of development rate(DVR) model for predicting bud break time of 'Niitaka' pear. In addition, the study also assessed the effect of an increase in temperature on predicting bud dormancy breaking time in winter season. The DVR model, which was developed for 'Kosui' pear, illustrated that the bud break time(e.g., Dec. 12-Dec. 19) of 'Niitaka' pear observed in the field corresponded to the predicted bud break time by DVR model. This result indicates that the bud break time of 'Niitaka' pear can be predicted by DVR model tuned for 'Kosui' pear. As the temperature increased during the winter season, the bud break time was delayed. Chilling requirement deficiency for the bud break time is expected in Jeju Province when the temperature increased above $4^{\circ}C$ in winter season.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.25 no.3
• /
• pp.172-181
• /
• 2023

In order to raise the self-sufficiency rate of domestic forage and obtain informations necessary for production of high-quality winter forage, forage yield and feeding value were analyzed in the above-ground parts of a winter wheat 'Cheongwoo' harvested at five different growth stages, and the appropriate harvest time was determined. The yield increased until 30 days after heading, and then decreased afterwards. The proportion of spike in the above-ground part was less than 40% until 30 days after heading, but increased to more than 60% afterward. At 30 days after heading, the protein content and relative feed value (RFV) also reached peaks, while acid detergent fiber (ADF) and neutral detergent fiber (NDF) were low. The mineral nutrient contents are within the standard range required for feeding ruminant livestock or do not exceed the maximum allowable level. Therefore, the best time to harvest above-ground parts of a winter wheat 'Cheongwoo' for use as a forage for feeding ruminant livestock is around 30 days after heading, when considering forage yield and feed values. As a result it would match well in time with the transplantation of rice seedlings or the sowing of rice-alternative field crops in the double cropping system.

• Fisheries and Aquatic Sciences
• /
• v.10 no.1
• /
• pp.43-52
• /
• 2007

The relationships among long-term climatic change in the southern part of the Korean peninsula, oceanic conditions of the South Sea, Korea, and winter catches of major small pelagic fishes were analyzed using 33 years of time-series data from 1971-2003. In the early 1990s, winter climatic conditions in the southern part of the Korean peninsula shifted to a warmer regime with higher air temperature, weaker wind speed, and lower relative humidity. Also, winter sea surface temperature (SST) became consistently higher in the South Sea. The annual catch of major small pelagic fishes in the South Sea increased dramatically in the mid 1990s, whereas the catch of total fishes decreased in the late 1980s. In particular, the winter catch started to increase markedly in the late 1980s, and has remained over 120,000 M/T since the late 1990s. Correlation analysis of the winter catch of major small pelagic fishes and environmental factors showed that catch was correlated with air temperature (r=0.468, P< 0.01), wind speed (r=-0.732, P< 0.01), relative humidity (r=-0.73l, P< 0.01), and SST (r=0.672, P< 0.01). Multiple regression analysis between the winter catch of major small pelagic fishes (Y) and environmental factors (X) resulted in the equation: $Y=-0.017-0.217\;X_3-0.486\;X_4+0.325\;X_5(R^2=0.754,\;P<0.000)$.