• International Journal of Fluid Machinery and Systems
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• v.8 no.1
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• pp.55-62
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• 2015

This study aims to present a hydraulic transitory study as MOC applications for solving the Saint-Venant equations in two case studies: 1) in a penstock of a small hydropower system as a simple pipeline in the case of valve-closure in the downstream boundary with a reservoir in the upstream boundary; and 2) for discharge propagation into a channel by velocity and depth of the flow channel along space evaluation. The proposed methodology by Chaudry [5] concerning the development of hydrodynamic models was used. The obtained results for first and second case study has been confirmed that MOC numerical approach is useful for several engineering purposes, including cases of hydraulic transients and discharge propagation in hydraulic systems.

• Journal of Species Research
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• v.9 no.4
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• pp.448-454
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• 2020

Nine free-living heterotrophic flagellates were cultured from marine intertidal sediments and freshwater sediments from Korea. These species are described with uninterpreted records based on light microscopy of living cells and reported taxonomically for the first time from Korea. Diagnostics of these species are as follows; Notosolenus hemicircularis: 9-11.8 ㎛ long with flagellar reservoir, ventrally flattened and dorsally convex with hyaline semicircular collar around short anterior neck, and 8 ridges on cell surface. Thecamonas tranhens: 4.5-7.1 ㎛ long, plastic with proboscis comprising an anterior flagellum surrounded by membranous sleeve. Bodomorpha minima: 4.5-7.0 ㎛ long, rigid with small rostrum in anterior end and active anterior flagellum. Cercomonas hiberna: 5.6-10.9 ㎛ long, very plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Cercomonas pellucida: 7.5-13 ㎛ long, plastic with pseudopodia, cytoplasmic strand and single contractile vacuole. With nucleus closely connected to basal bodies. Eocercomonas echina: 4.7-6.5 ㎛ long, plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas astra: 5.7-7.3 ㎛ long, moderately metabolic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas minima: 5-9 ㎛ long, metabolic with pseudopodia, cytoplasmic strand and single contractile vacuole. Paracercomonas producta: 6.1-9.9 ㎛ long, very metabolic with pseudopodia, long cytoplasmic strand and single contractile vacuole.

• Korean Journal of Veterinary Service
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• v.40 no.2
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• pp.95-99
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• 2017

Wild owls are widespread in Korea, even being common in urban areas due to the presence of hills or small mountains in and around the cities. This results in high levels of contact between owls and domestic animals. This study investigated the prevalence of avian hematozoan parasite infection in 2 common owl species in Chungbuk province of Republic of Korea for 3-year period: the Eurasian eagle owl (Bubo bubo) and the Brown hawk owl (Ninox scutulata). Peripheral blood smears taken from 56 wild owls were examined by microscopic examination and confirmed by molecular technique. Twenty (36%) of these samples tested positive for the Haemoproteus infection. The infection rate was higher in Brown hawk owls (50%) than in Eurasian eagle owls (33%). These results indicate that the wild owls may act as a reservoir for Haemoproteus infection in susceptible domestic birds.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.3
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• pp.127-133
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• 2017

Performance analysis has been carried out on a high side scroll compressor that had a fixed scroll equipped with a circular oil groove on its thrust surface. Oil was supplied to the oil groove through an intermittent opening from a high pressure oil reservoir formed inside the orbiting scroll hub. Oil in the groove was then delivered to both suction and back pressure chambers by pressure differentials and viscous pumping action of the orbiting scroll base plate. Mathematical modeling of this oil groove system was incorporated into a main compressor performance simulation program for an optimum oil groove design. The study findings were as follows. Pressure in the oil groove can be controlled by changing its configuration and the oil passage area. With an enlarged oil passage, the pressure in the oil groove heightens due to an increased flow rate, but the pressure elevation in the back pressure chamber is small, resulting in reduced friction loss at the thrust surface between the two scrolls. On the other hand, by increasing the oil passage area, the oil content in the refrigerant flow increases. Considering all these factors, the energy efficiency ratio could be improved by about 3.6% under the ARI condition by an optimal oil groove design.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.725-733
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• 2002

In this study, the heat transport limitations of a two-phase closed thermosyphon were investigated. For the test, a two-phase closed thermosyphon ($L_t/: 600 mm,\;L_e:105mm,\;L_a:75mm,\;L_c:420mm,\;D_o:22.2mm,$ container: copper (inner grooved surface), working fluid: PFC ($C_6F_14$) was fabricated with a reservoir that can change the fill charge ratio. The following was imposed as the factors on the heat transport limitations of a two-phase closed thermosyphon. 1) Fill charge ratio of the working fluid. 2) Tilt angle of the longitudinal axis. From tile experimental data, some results were obtained as follows. When the fill charge ratio was relatively small ($\psi$20%), the heat transport limitation occurred about 100W by dry-out limitation. However over 40%, it shelved nearly constant value (500 W) by flooding limitation. The heat transport limitation according to the tilt angle increased smoothly until the tilt angle was $60^{\circ}$,/TEX>, after then decreased slowly.

• Water for future
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• v.27 no.3
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• pp.145-158
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• 1994

The linear reservoir rainfall-runoff system was developed as a rainfall-runoff event simulation model. It was achieved from large modification of runoff function method. There are six parameters in the model. Hydrologic losses consist of some quantity of initial loss and some ratio of rainfall intensity followed by initial loss. The model has analytical routing equations. Hooke and Jeeves algorithm was used to model calibration. Parameters were estimated for flood events from '84 to '89 at Seomyeon and Munmak stream gauges, and the trends of major parameters were analyzed. Using the trends, verifications were performed for '90 flood event. Because antecedent fainfalls affect initial loss, future researches are required on such effects. The estimation method of major parameters should also be studied for real-time forecasting.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1832-1835
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• 2010

본 연구는 이상홍수와 급속한 도시화로 인하여 설계 및 축조 당시의 수문, 기상환경이 변화함에 따라 해마다 증가하는 저수지관련 홍수피해에 효율적으로 대처하기 위하여 국내 농업용 저수지 17,649개 중 14,154개(80.2%)에 해당하는 30만$m^3$ 이하의 소규모 저수지를 대상으로 댐 붕괴에 의한 저수지 하류의 피해 규모 및 피해양상을 정량화 할 수 있는 피해예측모델을 개발함으로써 저수지 하류하천 위험기준을 수립할 수 있는 방안을 제시하고자 한다. 이를 위해 경기도 용인시에 위치한 창리저수지(20.0만$m^3$)를 대상으로 댐 붕괴 시나리오를 작성하고 빈도별홍수량 및 가능최대홍수량(Probable Maximum Flood, PMF)을 산정하여 HEC-HMS 모형을 이용한 댐 붕괴 모의를 실시하였다. 하류부 홍수해석은 창리저수지 직하류 화곡천(1.12km) 구간에 대해 HEC-RAS 모형을 이용하여 댐 붕괴 홍수파 수문곡선에 따른 홍수범람도를 작성하였다. 또한 홍수범람구역에 해당되는 행정구역의 자산DB를 구축하고 홍수피해산정 방법으로 널리 사용된 다차원법(Multi - Dimensional Flood Damage Analysis, MD-FDA)과 기존 간편법의 장점을 살려 댐 붕괴에 따른 하류부 홍수피해액을 산정하였다.

• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.161-169
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• 2012

Recently various attempts have been made to apply HSPF model to calculate runoff and diffuse pollution loads of stream and reservoir watersheds. Because the role of standard flow is very important in the water quality modelling of Total Water Pollution Load Management, HSPF was used as a means of estimating standard flow. In this study, BASINS 4.0 and WinHSPF was applied to the Gomakwoncheon watershed, genetic algorithm(GA) and influence coefficient algorithm were used to calibrate the runoff parameters of the WinHSPF. The objective function is the sum of the squares of the normalized residuals of the observed and calculated flow and it is optimized using GA. Estimates of the optimum runoff parameters are made at each iteration of the influence coefficient algorithm. The calibration results showed a relatively good correspondence between the observed and the calculated values. The standard flow(Q275) of the Gomakwoncheon watershed was estimated using the ten years of weather data.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.588-592
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• 2012

저수지에서 퇴사가 저수지에 미치는 영향으로는 저수용량의 감소로 인한 용수공급량 저하, 상류하천 수위 상승에 따른 홍수소통능력 감소로 인한 배수위 상승, 퇴적토의 용출에 의한 부영양화 촉진 및 중금속 퇴적 등의 수질변화, 퇴사로 인한 어류서식처 환경의 변화 등이 있다. 또한, 저수지로 유입되는 유사에 대한 정확한 예측은 댐의 계획 및 운영과 관련된 저수지 퇴사관계를 이해하는데 필수 요소이다. 즉, 저수지 퇴사에 관한 예측 자료는 댐 설계시에 장래 50년 및 100년 후의 저수위-저수용량 관계곡선을 결정하고, 댐의 사수위를 결정하는데 중요한 기본자료이며, 또한 댐 건설후의 저수지내로 유입되는 유사의 공간적 퇴적분포를 예측하고, 기능별 저수지 용량배분, 본체 및 취수구 등 각종 수리구조물의 안정, 저수지 상류 퇴사로 인한 홍수위의 상승 등 저수지 제 기능의 적정 관리를 계획하는데 필요한 기본자료이기 때문이다. 본 연구에서는 저수지 내에서의 2차원적 하상변동을 해석하기 위한 퇴사 모델링 방법으로 2차원 정상 및 동수역학적인 유사이송과 하상변동을 모의할 수 있으며, 침식과 포착 및 이송 그리고 퇴적의 각 단계에 따라 세부모의가 가능할 뿐만 아니라 RMA2와 SMS 프로그램과 상호 연계가 자유로운 SED-2D 모형을 이용하여 댐 축조로 인한 저수지내의 퇴사거동을 모의한 후 하상변동을 분석하였다.

• Journal of Wetlands Research
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• v.8 no.4
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• pp.33-40
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• 2006

The water of rivers and lakes in Korea is the main sources for drinking, industrial and agricultural purposes. However, various pollutants washed-off from watershed area make worse and worse the water quality. Particularly, the changes of land uses in watershed area is the main pollutant sources in many cases in Korea, it is usually called to nonpoint pollution sources. In this reason, the Ministry of Environment are programing the total maximum daily load for four major large rivers in order to improve the water quality by controlling the watershed area. Therefore, this research was performed to estimate the total pollutant input from watershed areas to lakes of Ganwol and Boonam located in Chungnamdo. The AGNPS water quality model and monitoring were used to estimate the pollutant loading rates with unit pollutant concentration of each land use. The main landuse of the research area are forest, wet and dry paddy field and small urban area. The research shows that the pollutant sources in Ganwol and Boonam lakes are from the various landuses. In this manuscripts, the results will provide important informations for mitigating the pollutants to the lakes.