• Korean Journal of Hydrosciences
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• 제10권
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• pp.73-83
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• 1999

The intake towers of Buyeo W.T.P. in Keum river have being suffered from the sedimentation problems since the beginning of the operation. Impellers of the intake pumps have to the frequently changed due to the serious surface erosion. Thousands tons of sands are entrapped in the intake towers and equalization chambers of W.T.P. every year. Site surveying and numerical analysis were carried out to suggest an appropriate solution by understanding the general sedimentation regime of Keum river and causes of the sedimentation in the intake towers. Origin of the sediment could be found by the desk and site inspections. The validity of the used numerical models was examined by comparisons between the calculated bydraulic values and the measured ones during the specific periods. The design flow rate for the prediction of the future sedimentation regime of the rever was studied. The efficiency of the sediment control measures was also examined with the verified numerical models. Finally, it was found that the best solution could be a combination of three sediment control measures; increase the clearance between river bed and inlet, construct jetties at 2 kilometers upstream from the intake towers, and put vanes at the right side of the intake towers.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.166-169
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• 2006

Our country's coast is vulnerable area to natural disaster which the repetitive damages occur every year including a loss of lives, the damage of facilities and erosion mostly except for the east coast because of a typhoon, tidal waves, sea water overflowing by topographic structure of low-lying gentle slope and shallow sea. However, as for prevention of natural disaster occurring every year, the situation is that it's centered on the restorationcentered measures and the general disaster prevention research to minimize damages at the time of disaster occurrence is insufficient. This study intendedlop t to devehe techniques possible for real time sampling of damage prediction areas on Web in order to support decision making for damage prevention and establishment of disaster prevention policy. For this, the thematic map was produced related to disaster based on high-resolution satellite picture, and the environmental DB similar to real world was constructed through topographic construction of three-dimension integrating the parts of land and the sea. In addition, the system was developed possible for the expression of damageable regions by real time grasp of dangerous regions at the time of disaster occurrence through over flowing simulation of three-dimension, and it's intended to prepare a basis to minimize damages to disaster situations through it.

• 대한조선학회논문집
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• 제48권1호
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• pp.15-22
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• 2011

In this paper, cavitation patterns of model tests were compared with those of full-scale measurement for a propeller of crude oil carrier which was suffered from erosions on suction side of blade tip region. Cavitation tests were performed at design and ballast draft using model and full scale nominal wakes. A model ship and wire mesh method was used for the simulation of wake patterns of model nominal wakes. For the prediction of full-scale wake patterns, a RANS solver(Fluent 6.3) was used and wire mesh method was used for the simulation of the full scale wakes. Comparison results show that cavitation patterns using predicted full-scale wake patterns are closer to cavitation patterns of full-scale measurement at ballast draft condition. Also, cloud cavitations were observed on the position of eroded area at both full-scale measurement and cavitation tests using simulated full-scale wake patterns.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.832-840
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• 2019

Recently, pollution from gunpowder due to shell shootings at military drilling sites has raised various environmental concerns. The purpose of this study is to predict the contamination level of RDX in the soil area of the firing range zone near Anwol river watershed, the study site, and the intake area, Anwol river and Imjin river, as a function of time and space. In this study, a multimedia model was developed to predict the variation of RDX contamination by rainfall. The range of the medium was limited to soil, water, and sediment, and excluded the atmosphere, taking into account the physical and chemical properties of RDX with low vapor pressure and low Henry's constant. The pollutant levels of the waters of compartments, including the last section of the Imjin River affecting the water intake, was compared with the environmental standard for RDX.

• 한국산림과학회지
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• 제98권5호
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• pp.531-538
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• 2009

We used enzyme electrophoresis to evaluate genetic diversity in five populations of endemic ash, Fraxinus chiisanensis in Korea. Of 15 putative allozyme loci examined 26.7% were polymorphic and expected heterozygosity for the species was low (0.082). Within the range, population were highly differentiated ($F_{ST}$=0.356) and little genetic variation was explained by geography. The pattern of distribution of variation showed low genetic variation within populations and pronounced divergence among populations, which was consistent with the prediction for the effects of limited gene flow and local genetic erosion. Although the frequencies of male plants were dominant ranging from 79.3% to 89.4%, most mating events seems to be inevitable mating between relatives in small populations based on heterozygote deficiency of this species. Small effective population size and the limited dispersal contributed to the low rates of gene flow within as well as between populations.

• Water Engineering Research
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• 제5권1호
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• pp.47-54
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• 2004

Several computer programs have been developed to make stochastically generated weather data from observed daily data. But they require fully dataset to run WGEN. Mostly, meterological data frequently have sporadic missing data as well as totally missing data. The modified WGEN has data filling algorithm for incomplete meterological datasets. Any other WGEN models have not the function of data filling. Modified WGEN with data filling algorithm is processing from the equation of Matalas for first order autoregressive process on a multi dimensional state with known cross and auto correlations among state variables. The parameters of the equation of Matalas are derived from existing dataset and derived parameters are adopted to fill data. In case of WGEN (Richardson and Wright, 1984), it is one of most widely used weather generators. But it has to be modified and added. It uses an exponential distribution to generate precipitation amounts. An exponential distribution is easier to describe the distribution of precipitation amounts. But precipitation data with using exponential distribution has not been expressed well. In this paper, generated precipitation data from WGEN and Modified WGEN were compared with corresponding measured data as statistic parameters. The modified WGEN adopted a formula of CLIGEN for WEPP (Water Erosion Prediction Project) in USDA in 1985. In this paper, the result of other parameters except precipitation is not introduced. It will be introduced through study of verification and review soon

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.7-12
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• 2023

The edge ring placed on the outside of the electrostatic chuck (ESC) is a key component for protecting the ESC and controlling the etching uniformity of the edge of the wafer. Therefore, it is very important to understand the etching phenomenon of edge rings for edge ring management and equipment homeostasis. In this study, a specimen with SiO₂ hard mask and underlying Si mold was installed on the edge ring surface and the etching results were measured by varying the edge ring 2MHz RF power. By developing PI-VM model with high prediction accuracy and analyzing the roles of key parameters in the model, we were able to evaluate the effect of plasma and sheath characteristics around the edge ring on edge ring erosion. This analysis method provided information necessary for edge ring maintenance and operation.

• 대한토목학회논문집
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• 제12권3호
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• pp.173-180
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• 1992

자연 하천의 전형적인 특성인 하도사행으로 인한 만곡부의 수리 및 계량형태학적 특성을 확정론적 방법으로 구명하였다. 새로운 특성인자로 단변형상계수(As)을 제안했으며 하도구간에서의 As의 변화는 모든 유로에서의 수류력의 집중위치를 확인시켜주고 만곡의 영향이 단면형상의 변화에 미치는 영향을 정량적으로 보여주었다. 또한 기존의 사행특성인자와의 상관분석을 통하여 적용성을 입증하였다. 곡률비 R/W이 2-4에 집중되어있고 이는 제방의 침식이나 파제의 가능성이 있음을 보여주는 수치임을 알수있고 횡단면 하상의 변화를 예측할수있는 Bendegom의 식이 본 연구대상 하천에도 적용될수 있음을 밝혔다.

• 대한조선학회논문집
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• 제44권5호
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• pp.467-473
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• 2007

Cavitation phenomena appearing on ship propellers have long been interested and recent theoretical analysises give good results comparing with model tests. In accordance with a continuous rise in heavy powered and high speed ships, hull forms have been changed and loads acting on the propeller surface have also been increased, and they result in various and particular cavitations. In some cases, cavitation appears not only on the back but also on the face of the propeller and it causes additive pressure fluctuations and erosion of the propeller and reduces propulsion efficiency of the ship. In this study, we predict the face cavity inception using unsteady propeller analysis based on the panel method and compare the results with experimental observations.

• 대한토목학회논문집
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• 제11권4호
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• pp.81-89
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• 1991

사행하천형의 특성은 유로의 한쪽제방을 침식시키고, 다른 쪽은 퇴적을 일으키므로써 유로위치에 따라 천천히 형성되는데, 본 연구에서는 Odgaard(1986)가 제안한 횡방향 하상경사에 관한 선형 2차 미분방정식에 Langbein & Leopold(1966)가 제안한 sine-generated curve를 도입하므로써 위상차 및 폭-수심비의 영향을 고려한 새로운 하상형을 제시하고, 금강유역에 위치한 청원과 연기지역을 대상하천으로 하상변동조사보고서의 자료를 이용하여 비교분석한 결과 실측치와 잘 일치하였다.