• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.50-56
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• 2012

In this study, loess composites, loess with lanthanum and with aluminum, were made and evaluated for treatment of phosphorus removal in natural water system. Desiccation method for production of loess composite was superior to centrifugation method in obtaining high concentrated composites of lanthanum and aluminum. Washing of loess lanthanum composite by water did not deteriorat the lanthanum concentration in the composite, but this lowered the aluminum concentration of loess aluminum composite. Total of 15 and 37.5% of aluminum contents were removed after first washing treatment in aluminum loess of 0.05% and 0.1% respectively. However, no more aluminum loss was monitored with increase of washing times. Phosphorus removal efficiencies were not decreased with washed loess aluminum composite. Phosphorus removal was successfully achieved by adsorption of phosphate to loess composite at pH range of 5.0 ~ 8.0. Freundlich and Langmuir adsorption isotherm was observed in the adsorption of phosphate for loess composite. Dosages of 0.05% and 0.1% lanthanum composite for 95% of phosphorus removal could reduce its usage amount to 25% and 50%, respectively, comparing with dosage of loess alone. Dosages of 0.05% and 0.1% aluminum composite could reduce its usage amount to 48% and 63%, respectively.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.102-109
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• 2005

Water consumption at the farm is up to 48 percent of water resource of South Korea while manufacturing industry's is only $9.6\%$. The area of arable land is 2,077,067 ha and 27 percent of it is used for growing fruits and vegetables using furrow or surface irrigation at the greenhouse. Surface irrigation at the greenhouse for fruits and vegetables has problems such as over watering and insufficient supply of water to the fine roots of the plant. However, the research on the new method of irrigation to save water usage is few. The characteristics of soil wetting was measured for using surface irrigation and underground trickle irrigation method where water was supplied at 10, 15, 20, and 25 cm beneath the surface ground. Followings are summary of this study. 1. The efficiency of underground trickle irrigation was expected to be as high as twice of surface irrigation such as drip watering or sprinkling. 2. This improvement could be possible by using less than $50\%$ of irrigation water than surface irrigation to supply similar amount of water near fine roots. 3. Surface irrigation causes soil compaction as deep as 20 cm below the surface ground which reduces soil porosity and root respiration ending up developing less fine roots. 4. Underground trickle irrigation can prevent overdamping in the greenhouse since it does not over wet the surface soil. At winter, the amount of agricultural chemical usage could be reduced since this irrigation method does not develop blight or crop disease from condensation of water vapor.

• Hwankyungkyoyuk
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• v.23 no.4
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• pp.82-95
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• 2010

The Water Environmental Education Program Using Streams(WEES) is developed to help the teachers increase their professionalism of incorporating a local environment into their inquiry teaching. The purpose of this study is inquiry about the 'Baig Cheon' stream with the perspective of environmental studies for WEES. Through these studies, we tried to get the background information in 'Baig Cheon' and profound insights into application of WEES. The 'Baig Cheon' was examined from the perspective of environmental studies through literature study, field study, and water quality monitoring. The results revealed the characteristics of the 'Baig Cheon' that ran across a rural area in terms of the watershed boundaries, water systems, and water usage. The changes to the water quality items were observed according to the spatial distribution at the measuring points across the watershed for six months from March to August, 2007. The results indicate that the water quality of the 'Baig Cheon' could well be affected not only by the natural and environmental conditions such as the geological features, but also by the human activities including the land uses in the surrounding roads, rice fields and farms and the water supply and usage. The inquiry of the 'Baig Cheon' from the perspective of environmental studies will hopefully make the education and inquiry process of WEES more meaningful and in-depth and contribute to providing better environmental education that properly reflects the nature of inquiry from the perspective of environmental studies.

• Journal of Korea Water Resources Association
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• v.52 no.6
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• pp.441-449
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• 2019

Drought is a longer lasting and more extensive disaster than other natural disasters, resulting in significant socioeconomic damage. Even though drought events have same severity, their damage vary from region to region because of spatial, technical, economic, and social circumstances. In this study, drought vulnerability was assessed considering socioeconomic factors. Preliminary factors were identified from the case study for Chungcheong province, and evaluative factors were selected by applying the principal component analysis. The entropy method was applied to determine the weights of evaluative factors. As a result, in Chungcheong province, farm population, number of recipient of basic living, water fare gap indicator, area of industrial complex, amount of underground water usage, amount of water available per capita, water supply ratio, financial soundness for water resources, amount of domestic water usage, amount of agricultural water usage and agricultural land area were chosen as the evaluative factors. Among them, the factors associated with agriculture had larger weights. The overall assessment of vulnerability indicated that Cheongju, Dangjin and Seosan were the most vulnerable to drought.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.497-502
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• 2001

We examined the silicate-based material to develop the surface-treatment agent, which would be used to restore performance of the deteriorated concrete and to inhibit corrosion of the reinforcing bar. As a part of the study, we carried out experiments of the penetration and strengthening properties of concrete treated by the considering agent. The variables of experiment, were the type of silicates, the ratio of distilled water-silicate, the usage of surface-strengthening material, and the usage of biochemical material. The penetrating ability of concrete is assessed by viscosity and surface tension. Also assessments of strengthening effects of concrete are performed on compressive strength, absorption, and water permeability tests.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.3
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• pp.1-8
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• 1994

In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2839-2844
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• 2008

A PEMFC(proton exchange membrane fuel cell) is a good candidate for residential power generation to be cope with the shortage of fossil fuel and green house gas emission. The attractive benefit of the PEMFC is to produce electric power as well as hot water for home usage. Typically, thermal management of vehicular PEMFC is to reject the heat from the PEMFC to the ambient air. Different from that, the thermal management of PEMFC for RPG is to utilize the heat of PEMFC so that the PEMFC can be operated at its optimal efficiency. In this study, dynamic thermal management system is modeled to understand the response of the thermal management system during dynamic operation. The thermal management system of PEMFC for RPGFC is composed of two cooling circuits, one for controling the fuel cell temperature and the other for heating up the water for home usage. Dynamic responses and operating strategies of the PEMFC system are investigated during load changes.

• KIEAE Journal
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• v.14 no.2
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• pp.11-19
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• 2014

Building energy consumption takes up almost 25% of the total energy consumption. Therefore, diversified ways, such as improving wall and window insulation, have been considered to reduce building energy consumption. Recently, green roof system has been explored as an effective alternative for dealing with reducing heating and cooling energy, thermal island effect and improving water quality. However, recent studies regarding a green roof system have only focused on building energy reduction without considering the applied usage, location, and story of the green roof system. Therefore, this study pays attention to the heating and cooling energy in relation to the applied usage, location, and story of a green roof system for investigating its impact on energy reduction. The result of simulations show that the reduction in heating energy consumption is higher when applied to Cherwon-gun province which has a continental climate condition, compared to the city of Busan that is distinguished by its warm climate. Cooling energy saving turns out to be higher when the green roof system is applied to Busan in comparison with Cherwon. As for the applied usage or function of the building, residential space acquires the highest heating and cooling energy saving effect rather than commerce, educational or office space because of HVAC's running time based on usage. When it comes to the story of the green roof, both heating and cooling energy saving become the highest when the green roof is applied to single-storied buildings. The reason is that single story building is affected by the ground largely. Generally, the variations of heating energy consumption are larger than the cooling energy consumption. The outcome of the simulations, when a green roof system is applied, indicates that the energy consumption reduction rate is dynamically responding to the applied usage, location, and story. Therefore, these factors should be counted closely for maximizing the reduction of energy consumption through green roof systems.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.113-125
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• 2013

According to 2012 OECD environmental report, Korea was ranked as the first country of water stress. Water footprint is a method to calculate water usage during the life cycle of a product from material procurement through production to disposal to recycle and to quantify the load to water resources. In water footprint calculation, water consumption unit is used. Agricultural water use is over 48% so it is urgent to mange that area Korea needs to spread the discussion about water footprint as quickly as possible, for the study to prevent social and environmental problems due to water shortage. This paper, through water footprint calculation and comparison in Chungju and Geochang areas, looks to counter measures for water risk, targeting domestically-produced apple.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.795-801
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• 1998

Metallic fatigue of Pressurized Water Reactor(PWR) materials is a generic safety issue for commercial nuclear power plants. It is very important to obtain the fatigue usage factor for component integrity and life extension. In this paper, fatigue usage was obtained at the inside surface of Kori unit 2, 3 and 4 RCP casing weld, based on the design transient. And it was intended to establish the procedure and the detailed method of fatigue evaluation in accordance with ASME Section III Code. According to this code rule, two methods to determine the stress cycle and the number of cycles could be applied. One method is the superposition of cycles of various design transients and the other is based on the assumption that a stress cycle correspond to only one design transient. Both method showed almost same fatigue usage in the RCP casing weld.