• Korean Journal of Soil Science and Fertilizer
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• v.7 no.1
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• pp.55-64
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• 1974

Effect of tow or three week potassium depression on nutrient contents in two rice varieties, Jinheung (a leading local) and IR 667-Suwon 214 (high yielding tropical line), was investigated at various growth stages in water culture system for the nutritional elucidation of potassium top dressing. According to potassium content, potassium ratio beween leaf blade and leaf sheath plus culm, relative potassium content ($-k/+k{\times}100$) and balance between potassium and other nutrients (K/N or K/Ca+Mg) it could be concluded as follows: 1) Rice plants have three sensitive growth stages to potassium stress in the orther of ear formation stage (20 to 30 days before heading) early tillering (15 to 25 days after transplanting) and at heading. 2) IR 667 is more sensitive to potassium stress than Jinheung, especially in early stage due to lower uptake of potassium. 3) Leaf sheath of IR 667 appears to have a role as potassium reservoir to greater extent than that of Jinheung.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.194-201
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• 2005

Silicate (Si) fertilizers are well-known for soil amendment and to improve rice productivity as well as nitrogen efficiency. In this study, we investigated the possible reduction level of nitrogen fertilization for rice cultivation by amending Si fertilizer application. Field experiments were carried out to evaluate the productivity of rice (Oryza sativa L.) on a silt loam soil, where three levels of nitrogen (0, 110 and $165kg\;ha^{-1}$) were selected and Si fertilizer as a slag type was applied at 0, 1 and 2 times of the recommendation level (available $SiO_2\;130mg\;kg^{-1}$). Application of Si fertilizer increased significantly the rice yield and nitrogen efficiency. With increasing N uptake of rice, 1 and 2 times of recommended levels of Si fertilization could decrease nitrogen application level to about 76 and $102kg\;N\;ha^{-1}$ to produce the target yield, the maximum yield in the non-Si amended treatment. Silicate fertilizer improved soil pH and significantly increased available phosphate and Si contents. Conclusively, the Si fertilizer could be a good alternative source for soil amendment, restoring the soil nutrient balance and to reduce the nitrogen application level in rice cultivation.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.75-84
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• 2023

Many developing countries face challenges in estimating long-term discharge due to the lack of hydrological data for water supply planning, making it difficult to establish a rational water supply plan for decision-making on water distribution. The study area, the Bandung region in Indonesia, is experiencing rapid urbanization and population concentration, leading to a severe shortage of freshwater. The absence of water reservoir prediction methods has resulted in a water supply rate of approximately 20%. In this study, we aimed to propose an approach for predicting water reservoirs in developing countries by analyzing water safety and potential water supply using the MODSIM (Modified SIMYLD) network model. To assess the suitability of the MODSIM model, we applied the unit hydrograph method to calculate long-term discharge based on 19 years of discharge data (2002-2020) from the Pataruman observation station. The analysis confirmed alignment with the existing monthly optimal operation curve. The analysis of power plant capacity revealed a difference of approximately 0.30% to 0.50%, and the water intake safety at the Pataruman point showed 1.64% for Q95% flow and 0.47% for Q355 flow higher. Operational efficiency, compared to the existing reservoir optimal operation curve, was measured at around 1%, confirming the potential of using the MODSIM network model for water supply evaluation and the need for water supply facilities.

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.7-12
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• 2013

Environmental measurements in the many different types of horticultural farms were carried out to evaluate the ventilation performance for multi-span plastic greenhouses according to the eaves height, the number of spans, the existence of side wall vents and the position of roof vents. Hydroponic tomatoes were being cultivated in all experimental greenhouses, and ventilation rates of the greenhouses were analyzed by the heat balance method. It showed that the ventilation rate in the greenhouse with 4 m eaves height increased about 22% compared to the greenhouse with 2 m eaves height. The ventilation rate in the greenhouse with 9 spans decreased about 17% compared to the greenhouse with 5 spans. In the greenhouse with 9 spans, if there were no side wall vents, the ventilation rate showed about a third of the case that side wall vents were open. Overall, as the eaves height was higher and the number of spans was smaller in multi-span greenhouses, the natural ventilation performance was better. And the ventilation performance was best in the greenhouse which the eaves height was high and the position of roof vents was ridge, not gutter. Therefore, in order to maximize the natural ventilation performance, multi-span plastic greenhouses need to improve their structures such as that make the eaves height higher, place the roof vents on the ridge, install the side wall vents as much as possible, and the number of spans is limited to about 10 spans.

• Journal of Environmental Impact Assessment
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• v.28 no.1
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• pp.23-34
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• 2019

Global warming becomes a serious issue that poses subsidiary issues like a sea level rise or a capricious climate over the world. Because of severe heat-wave of the summer in Korea in 2016, a big attention has been focused on urban heat island since then. Not just about heat-wave itself, many researches have been concentrated on how to adapt in this trendy warming climate and weather in a small scope. A big part of existing studies is mitigating "Urban Heat Island effect" and that is because of huge impervious surface in urban area where highly populated areas do diverse activities. It is a serious problem that this thermal context has a high possibility causing mortality by heat vulnerability. However, there have been many articles of a green infrastructures' cooling impact in summer. This research pays attention to measure cooling effect of a street planting considering urban canyon and type of green infrastructures in neighborhood scale. This quantitative approach was proceeded by ENVI-met simulation with a spatial scope of a commercial block in Seoul, Korea. We found the dense double-row planting is more sensitive to change in temperature than that of the single-row. Among the double-row planting scenarios, shrubs which have narrow space between the plant and the land surface were found to store heat inside during the daytime and prevent emitting heat so as to have a higher temperature at night. The quantifying an amount of vegetated spaces' cooling effect research is expected to contribute to a study of the cost and benefit for the planting scenarios' assessment in the future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.198-205
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• 1982

In 1980, rice was considerably damaged by abnormal low temperature. In this paper, to determine the effect of low temperature on the growth and nutrition of rice, the experiment were carried out: varietal response to low temperature in the region with different elevations. Regional differences of heading response to low temperature were observed among varieties. The difference of days between regions were bigger in tongil lines than Japonica lines. Especially, Milyang 42 and Hangangchalbeo might belong the cold suceptible group, since the varieties were severely delayed their heading in the high mountainous region as comparred to plain region. The delay of heading with low temperature was brought out grain sterility, and fertility and ripening ratio is influenced cold tolerance and elevations, and it's decreased yield. Varieties with higher grain sterility by low temperature have higher total nitrogen content, but tended to have lower potassium and phosphate contents in the flag leaf. High content of total nitrogen, low contents of potassium and silicate were observed in the sterilized grain chaff an the opposite result were noted in the ferilized grain chaff at the ripening stage. The results reveal that the balance of these mineral element may play an important role in ripening and possibly cold tolerance.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.103-112
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• 2011

The main objective of this research was to estimate Nitrogen budget of South Korea in 2008. Input-output budgets for nitrogen fluxes were categorized into three sections: cities, agricultural area, and forest. Chemical and biological fixation, dry and wet deposition, imported food and feed were used as the nitrogen input. Crop uptake, volatilization, denitrification, leaching, runoff, and forest consumption were used as the nitrogen outputs. Annual total nitrogen input was 1,294,155 ton/yr, and output was 632,228 ton/yr. Comparison with a previous research in 2005 indicates that nitrogen input was decreased by 1.9% due to the decrease in nitrogen fertilizer while nitrogen output was decreased by 6.3%. Non-point source (NPS) pollution was also estimated by mass balance approach, which increased by 22% than the previous research in 2005. The emission of nitrous oxide ($N_2O$) caused by denitrification was newly examined in this research. About 8,289 ton/yr of $N_2O$ was released from agriculture area and domestic wastewater treatment plant.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.52-57
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• 2005

Previous studies showed that shell meal fertilizer from the oyster farming industry could be a potential inorganic soil amendment to increase Chinese cabbage productivity and to restore the soil nutrient balance in upland soil (Lee et al., 2004). Herein, shell meal fertilizer was applied at rates of 0, 4, 8, 12, and $16Mg\;ha^{-1}$ to upland soil (Pyeontaeg series, Fine silty, Typic Endoaquepts) for Chinese cabbage cultivation. We found available phosphate increased significantly with shell meal fertilizer application, due to high content of phosphate ($1.5g\;P_2O_5\;kg^{-1}$) in the applied shell meal fertilizer. In addition, high pH of shell meal fertilizer contributed to increase available phosphate content by neutralization of acidic soil. Total and residual P contents increased significantly with increasing shell meal fertilizer application, but we could not find any tendency in organic and inorganic P fraction. Of extractable P fraction, water-soluble phosphorus (W-P) and calcium-bound P (Ca-P) contents increased significantly with increasing application level. By contrast, aluminum and iron-bound P (Al-P and Fe-P) decreased slightly with shell meal application. The present experiment indicated that shell meal fertilizer had a positive benefit on increasing available phosphate content in arable soil. And so the increased available phosphate by shell meal fertilizer may decrease phosphate application level and then reduce phosphorus loss in arable soil.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.229-238
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• 2022

Animal pollination is an important ecosystem service provided mostly by diverse insect groups such as bees and hover flies. Maintaining agricultural productivity and securing the nutritional balance are closely tied to human wellbeing. This study aimed to estimate the pollination dependent food production in Korean agricultural system. Crop production data were obtained from Korean statistical information service (KOSIS) data of 2015. By implementing pollination dependency, crop production and market price, contribution of insect pollination to crop production increase were estimated from total 71 crops including 12 cereals, 19 fruits, 18 field vegetables, 13 greenhouse vegetables and 9 specialty crops. Mean pollination dependency of all crops were 29.2% and it was higher on fruits, specialty crops and greenhouse vegetables as well, but low (7.5%) in cereal crops. Pollination dependent (PD) production was estimated as 17.8% of total agricultural crop production with the economic value of 6,850 (6,508-7,193) billion won. Especially, PD production of greenhouse vegetables accounted 49.2% followed by fruits of 42.9%. Even specialty crop also showed higher PD production (35.9%). It was obvious that pollination is the vital service for agricultural production as well as nutritional security in Korea. Further protection and enhancing the pollination service were discussed with integrated pollinator-pest management (IPPM) strategies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.1-6
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• 2019

The objective of this study was to investigate performance characteristics of thermal management system(TMS) in a fuel cell electric vehicle with 100kW Fuel Cell(FC) system. In order to build up analytic modelling for TMS, each component was installed and tested under various operating conditions, such as water pump, radiator, 3-Way valve, COD heater, and FC stack etc. and as the results of them, correlations reflecting component's characteristics with flow rate, air velocity were developed. Developed analytic modelling was carried out under various operating conditions on the road. To verify modelling's accuracy, after prediction for optimum coolant flow rate was fulfilled under certain operating conditions, such as FC system, water pump speed, opening of 3-way valve, and pipe resistance, analytic and experimental values were compared and good agreement was shown. In order to predict cold-start operating performance for analytic modelling, coolant temperature variation was analyzed with $-20^{\circ}C$ ambient temperature and duration was predicted to rise in optimum temperature for FC. Because there is appropriate temperature difference between inlet and outlet of FC stack to operate FC system properly, related analysis was performed with respect to power consumption for TMS and heat rejection rate and performance map was depicted along with FC operating conditions.