• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.200-209
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• 2011

The purpose of the study is to optimally manage sewage treatment plant with analysis of phosphorus contribution and improvement of water quality contributing rate in the effect of inflowing point of effluent and Pal-Dang lake after reducing T-P discharge from large scale public sewage treatment plant at upstream of Pal-Dang lake. Also, this study, for enforcement of T-P in effluent, plans optimal management of effluent T-P through examining propriety of environmental, technological, and economical aspect such as water quality standard of domestic and foreign T-P and related policy. In regarding optimal management of T-P discharged from public sewage treatment plant located in upstream of Pal-Dang lake, the study drew following conclusions. With the optimal management of public sewage treatment plant, it showed that a pollution level became higher in the order of Sumgang E in South-Han river, C in Dalcheon, B1 B2, A in North-Han river, and J in Kyungancheon, and it is required reduction of T-P first. The highest value in analysis of benefit-costs from sewage treatment plant in the selected research area was Kyungan B, and the others are with the order of Jojong A, Bokha A, Kyungan A, and Yanghwa A. With result of this study, all 14 areas are required more enforced phosphorus treatment. The study resulted that the most top priority areas were Hangang F, Sumgang B, and Gyungan A, top priority areas were Bokha A, Dalcheon B, and Cheongmi A, priority areas were Hangang E, Heukcheon A, Gyungan B, and Jojong A, and potential areas were Sumgang A, Yanghwa A, Dalcheon A, and Hangang D. It seems to be appropriate to apply 0.2 mg/L of T-P treatment for water supply source reservation, 0.5 mg/L for the other areas by locally, and 0.2~0.5 mg/L for biological nitrogen phosphorus treatment method and 0.5~1 mg/L for Conventional Activated Sludge by technologically. Also, it may be appropriate to apply 0.2 mg/L for the most top priority area(I), 0.3 mg/L for the top priority area(II), 0.4 mg/L for priority area(III), and 0.5 mg/L for potential area(IV) by the separation of priority area.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.733-742
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• 2016

In recent years, gas engines fueled with LNG or synthetic gas have been attracting considerable attention for marine use owing to their potential to facilitate better fuel economy and to reduce emissions. It has been confirmed that gas engines using the Otto cycle, which involves premixed combustion, can satisfy Tier III regulations without the EGR or SCR system. The objective of this study is to acquire simulation technologies for predicting gas engine performances in industrial fields. Using the commercial software BOOST, the simulation is conducted on a gasoline engine rather than a marine engine due to the gasoline engine's easier accessibility. This study consists of two stages. In the first stage published previously, the optimal modeling techniques for representing the behavior of the gas in the intake and exhaust systems were determined. In the current study, we formulated a method to evaluate the combustion and heat transfer processes in the cylinder and to ultimately determine the major performance parameters, given that the analytical model derived from the previous stage has been applied. Through this study, we were able to determine a combustion and heat transfer model and a valve discharge coefficient that are less reliant on empirical data: we were also able to formulate a methodology through which relevant constants are decided. We confirmed that the values of transient cylinder pressure variation, indicated mean effective pressure, and air supply can be successfully predicted using our modeling techniques.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.967-972
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• 2003

The inner-diameter 5 cm cold hollow cathode ion source was designed for the high current density and the homogeneous beam profile of ion beam. The ion source consisted of a cylindrical cathode, a generation part of magnetic field, a plasma chamber, convex type ion optic system with two grid electrode, and DC power supply system. The cold hollow cathode ion sources were classified into standard type (I), electron output electrode modified type (II). The operation of the ion source was done with discharge current, ion beam potential and argon gas flow rate. The modification of electron output electrode resulted in uniform plasma generation and uniform area of ion beam was extended from 5 cm to 20 cm. Improved ion source was evaluated with beam uniformity, ion current, team extraction efficiency, and ionization efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2B
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• pp.121-135
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• 2010

This study is to assess the effect of potential future climate change on the inflow of agricultural reservoir and its impact to downstream streamflow by reservoir operation for paddy irrigation water supply using the SLURP. Before the future analysis, the SLURP model was calibrated using the 6 years daily streamflow records (1998-200398 and validated using 3 years streamflow data (2004-200698 for a 366.5 $km^2$ watershed including two agricultural reservoirs (Geumgwang8 and Gosam98located in Anseongcheon watershed. The calibration and validation results showed that the model was able to simulate the daily streamflow well considering the reservoir operation for paddy irrigation and flood discharge, with a coefficient of determination and Nash-Sutcliffe efficiency ranging from s 7 to s 9 and 0.5 to s 8 respectively. Then, the future potential climate change impact was assessed using the future wthe fu data was downscaled by nge impFactor method throuih bias-correction, the future land uses wtre predicted by modified CA-Markov technique, and the future ve potentiacovfu information was predicted and considered by the linear regression bpowten mecthly NDVI from NOAA AVHRR ima ps and mecthly mean temperature. The future (2020s, 2050s and 2e 0s) reservoir inflow, the temporal changes of reservoir storaimpand its impact to downstream streamflow watershed wtre analyzed for the A2 and B2 climate change scenarios based on a base year (2005). At an annual temporal scale, the reservoir inflow and storaimpchange oue, anagricultural reservoir wtre projected to big decrease innautumnnunder all possiblmpcombinations of conditions. The future streamflow, soossmoosture and grounwater recharge decreased slightly, whtre as the evapotransporation was projected to increase largely for all possiblmpcombinations of the conditions. At last, this study was analysed contribution of weather, vegetation and land use change to assess which factor biggest impact on agricultural reservoir and stream watershed. As a result, weather change biggest impact on agricultural reservoir inflow, storage, streamflow, evapotranspiration, soil moisture and groundwater recharge.