• 농촌계획
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• 제8권2호
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• pp.17-26
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• 2002

The purpose of this study was to investigate the changes of the sea bottom topology during construction of Saemangeum seadikes. Sea water depth and bottom topology in the Saemangeum area were measured every year and the surveyed data under construction of Saemangeum seadikes were analyzed and compared to the initial conditions before construction, There was erosion in the overall surveyed areas and the depth of erosion was approximately 53cm compared to the data in 1988. The center sandbanks of Seadike 2 did not show the great changes due to two main channels those were developed in northeast and southeast. The inland sandbanks of Seadike 4 showed the development of great erosion and deposition partially because of the changes in tide direction which developed as a result of the completion of Seadike 3 and the completion of a seadike of the Kunsan-Changhang industrial park at the north of Saemangeumm area.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2002년도 학술발표회 논문집(I)
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• pp.27-40
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• 2002

Developed at Colorado State University, CASC2D-SED is a physically-based model simulating the hydrologic response of a watershed to a distributed rainfall field. The time-dependent processes include: precipitation, interception, infiltration, surface runoff and channel routing, upland erosion, transport and sedimentation. CASC2D-SED is applied to Goodwin Creek, Mississippi. The watershed covers 21 $\textrm{km}^2$ and has been extensively monitored both at the outlet and at several internal locations by the ARS-NSL at Oxford, MS. The model has been calibrated and validated using rainfall data from 16 meteorological stations,6 stream gaging stations and 6 sediment gaging stations. Sediment erosion/deposition rates by size fraction are predicted both in space and time. Geovisualization, a powerful data exploration technique based on GIS technology, is used to analyze and display the dynamic output time series generated by the CASC2D-SED model.

• Transactions on Electrical and Electronic Materials
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• 제5권1호
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• pp.11-14
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• 2004

An rf triode magnetron sputtering system is designed and installed its construction in vacuum chamber. In order to calibrate the rf triode magnetron sputtering for thin films deposition processes, the effects of different glow discharge conditions were investigated in terms of the deposition rate measurements. The basic parameters for calibrating experiment in this sputtering system are rf power input, gas pressure, plasma current, and target-to-substrate distance. Because a knowledge of the deposition rate is necessary to control film thickness and to evaluate optimal conditions which are an important consideration in preparing better thin films, the deposition rates of copper as a testing material under the various sputtering conditions are investigated. Furthermore, a triode sputtering system designed in our team is simulated by the SIMION program. As a result, it is sure that the simulation of electron trajectories in the sputtering system is confined directly above the target surface by the force of E${\times}$B field. Finally, some teats with the above 4 different sputtering conditions demonstrate that the deposition rate of rf triode magnetron sputtering is relatively higher than that of the conventional sputtering system. This means that the higher deposition rate is probably caused by a high ion density in the triode and magnetron system. The erosion area of target surface bombarded by Ar ion is sputtered widely on the whole target except on both magnet sides. Therefore, the designed rf triode magnetron sputtering is a powerful deposition system.

• 한국항해항만학회지
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• 제43권1호
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• pp.64-71
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• 2019

낙동강 하구의 지형변화 메커니즘을 파악하는 것은 하구의 관리방안과 처리방법 연구에 매우 중요하다. 본 연구에서는 낙동강 하구의 지형변화에 관여하는 강우, 하천유량, 유사량과 같은 육역으로부터 영향과 조석, 조류, 파랑, 표층퇴적물 등과 같은 해역으로부터의 영향을 조사 분석하였다. 분석된 자료에 근거하여 지형변화 실험을 수행하고, 지형변화와 외력조건별 기여도를 분석하였다. 수치실험 결과 지형변화는 하굿둑 방류 영향을 직접적으로 받는 수로부를 중심으로 침식이, 간접 영향권인 간석지를 중심으로 퇴적이 우세하게 나타났다. 수로부를 따라 이동되는 퇴적물이 파랑에 의해 분급, 배분되면서 울타리선 전면부에는 퇴적이 우세하였다. 지형변화 실험결과인 퇴적 우세현상과 비교하여, 외력조건별로 침식의 기여도가 크게 나타나고 있으나 각 외력조건의 복합적인 영향은 퇴적이 우세하게 나타나고 있다. 따라서, 낙동강 하구의 지형변화는 여러 복합적인 외력인자의 결과로 판단된다. 또한, 각 외력조건별 영향은 구역별로 상이한 기여도를 보이므로 하구관리방안 수립시 이러한 결과를 고려해야 하고, 반드시 복합적인 상호작용의 결과로 이해하고 있어야 할 것으로 사료된다.

• 한국재료학회지
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• 제28권2호
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• pp.75-81
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• 2018

An ultra-high temperature ceramic, tantalum carbide, has received much attention for its favorable characteristics: a superior melting point and chemical compatibility with carbon and other carbides. One drawback is the high temperature erosion of carbon/carbon (C/C) composites. To address this drawback, we deposited TaC on C/C with silicon carbide as an intermediate layer. Prior to the TaC deposition, the $TaCl_5-C_3H_6-H_2$ system was thermodynamically analyzed with FactSage 6.2 and compared with the $TaCl_5-CH_4-H_2$ system. The results confirmed that the $TaCl_5-C_3H_6-H_2$ system had a more realistic cost and deposition efficiency than $TaCl_5-CH_4-H_2$. A dense and uniform TaC layer was successfully deposited under conditions of Ta/C = 0.5, $1200^{\circ}C$ and 100 torr. This study verified that the thermodynamic analysis is appropriate as a guide and prerequisite for carbide deposition.

• 한국토양비료학회지
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• 제41권4호
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• pp.235-238
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• 2008

토양침식을 예측하는 WEPP(Water Erosion Prediction Project)모델은 연방 정부기관이 토양과 물 보전 및 환경을 계획하고 평가하는데 활용하고자 1985년 8월 차세대 물에 의한 토양침식을 예측하기 위해 만들어졌다. 미농무성 농업연구소에 의해 개발된 WEPP 모델은 경험적인 침식 예측을 위한 도구로써 침투, 유거수, 강우와 물에 의한 토양입자의 분리, 침전물의 이동, 퇴적, 작물의 생장 및 수확 후 잔여물의 분해 등을 포함한 토양 침식과 관련된 많은 중요한 물리적 과정을 모의한다. WEPP 모델은 모델을 구성하는 모듈의 입력자료와 모델을 시험하기 위해서 필요한 자료를 경작지, 초지, 산림 등 광대한 현장 실험 결과들로부터 얻었다. 미국내 여러 농업연구소와 협력 대학 등 수 많은 연구소의 큰 노력으로 모델을 만들 수 있었다. WEPP 모델은 경사지 혹은 작은 유역 규모에 적용이 가능하며, 물리적 모델이기 때문에 미국과 다른 여러 나라에서 중요한 자연자원을 효과적으로 평가할 수 있다. 최근 들어 DOS프로그램으로 만들어진 초기 WEPP모델을 윈도우 인터페이스와 GIS프로그램을 통합하여 향상시켰다. 또한, 바람과 물에 의한 침식을 통합 예측하는 시스템을 쉽게 이용할 수 있도록 구축 중에 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2005년도 제28회 학술발표회 초록집
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• pp.76-76
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• 2005

• Fisheries and Aquatic Sciences
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• 제13권2호
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• pp.167-181
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• 2010

To predict changes in the marine environment of the Beolgyo Stream Estuary in Jeonnam Province, South Korea, where cohesive tidal flats cover a broad area and a large bridge is under construction, this study conducted numerical simulations involving tidal flow and cohesive sediment transport. A wetting and drying (WAD) technique for tidal flats from the Princeton Ocean Model (POM) was applied to a large-scale-grid hydrodynamic module capable of evaluating the flow resistance of structures. Derivation of the eddy viscosity coefficient for wakes created by structures was accomplished through the explicit use of shear velocity and Chezy's average velocity. Furthermore, various field observations, including of tide, tidal flow, suspended sediment concentrations, bottom sediments, and water depth, were performed to verify the model and obtain input data for it. In particular, geologic parameters related to the evaluation of settling velocity and critical shear stresses for erosion and deposition were observed, and numerical tests for the representation of suspended sediment concentrations were performed to determine proper values for the empirical coefficients in the sediment transport module. According to the simulation results, the velocity variation was particularly prominent around the piers in the tidal channel. Erosion occurred mainly along the tidal channels near the piers, where bridge structures reduced the flow cross section, creating strong flow. In contrast, in the rear area of the structure, where the flow was relatively weak due to the formation of eddies, deposition and moderated erosion were predicted. In estuaries and coastal waters, changes in the flow environment caused by artificial structures can produce changes in the sedimentary environment, which in turn can affect the local marine ecosystem. The numerical model proposed in this study will enable systematic prediction of changes to flow and sedimentary environments caused by the construction of artificial structures.

• 한국항만학회지
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• 제14권4호
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• pp.451-461
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• 2000

The design and maintenance of navigation channel and water facilities of an harbor which is located at the mouth of river or at the estuary area are difficult due to the complexity of estuarial water and sediment circulation. Effects of deepening navigable waterways, of changing coastline configurations, or of discharging dredged material to the open sea are necessary to be investigated and predicted in terms of water quality and possible physical changes to the coastal environment. A borad analysis of the transport mechanism in the estuary area was made in terms of sediment property, falling velocity, concentration and flow characteristics. In order to simulate the transport processes, a two-dimensional finite element model is developed, which includes erosion, transport and deposition mechanism of suspended sediments. Galerkin’s weighted residual method is used to solve the transient convection-diffusion equation. The fluid domain is subdivided into a series of triangular elements in which a quadratic approximation is made for suspended sediment concentration. Model could deal with a continuous aggregation by stipulating the settling velocity of the flocs in each element. The model provides suspended sediment concentration, bed shear stress, erosion versus deposition rate and bed profile at the given time step.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.605-609
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• 2010

기상변화와 지구온난화로 인해 국지성 호우의 강도와 빈도가 늘어나고 있으며 이로 인해 소양강, 도암댐, 임하댐 유역의 탁수 문제 등, 토양 유실에 관한 문제가 심각해지고 있다. 정확한 토양 유실 모의를 위하여 지난 수 십 년간 Universal Soil Loss Equation(USLE) 등의 모형이 사용되었지만 이러한 모형들에 관한 연구 중 강한 집중 호우에 의해 발생하는 걸리 침식(Gully Erosion)을 적용한 경우는 많지 않다. 이에 본 연구에서는 걸리 침식을 고려한 토양 유실량 및 유사량 산정을 위하여 입력자료가 간단하고 ArcView GIS를 기반으로 융합이 가능한 Sediment Assessment Tool for Effective Erosion Control (SATEEC) system, nLS, Unit Stream Power-based Erosion/Deposition (USPED) 연계 모형을 개발하여 강원도 양구군 해안면 유역에 적용하였다. 기존 SATEEC system에서는 강우 시 유역에서 발생하는 면상 침식(Sheet Erosion), 세류 침식(Rill Erosion)의 모의만이 가능하였지만, 본 연구에서 개발한 연계모형에서는 nLS 모형을 이용한 걸리 헤드 발생 지역 선정과 USPED 모형을 이용한 걸리 발생 지역에서의 토양 유실량 산정이 가능하기 때문에, 걸리 침식을 고려한 토양 유실량 산정이 가능하다. 연계 모형의 모의 결과 해안면 유역의 최종 유출구에서 발생하는 평균 유사량은 101,933 ton/year 로 산정 되었다. 토양 유실량과 유사량을 모의함에 있어, 면상, 세류, 걸리 침식을 종합적으로 고려해야 실제 지형에서 발생하는 토양 유실량 및 유사량을 좀 더 정확하게 예측할 수 있을 것이며, 본 연구에서 개발된 연계 모형을 이용한다면 실제 유역에서 발생하는 여러 형태의 토양 유실을 모의 할 수 있을 것이라 판단된다.