• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.564-572
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• 2019

Numerical simulation of the sediment by the Delft3d model was conducted to examine the changes in the sediment budget transport caused by long-term wave changes at the Maengbang beach. Representative waves were generated with input reduction tools using NOAA NCEP wave data for about 40 years, i.e., from January 1979 to May 2019. To determine the adequacy of the model, wave and depth changes were compared and verified using wave and depth data observed for about 23 months beginning in March 2017. As a result of the error analysis, the bias was 0.05 and the root mean square error was 0.23, which indicated that the numerical wave results were satisfactory. Also, the observed change in depth and numerical result were similar. In addition, to examine the effect due to long-term changes in the waves, the NOAA wave data classified into each of the representative wave grades, and then the annual trend of the representative wave was analyzed. After deciding the weight of each wave class considering the changed wave environment in 2100, the amounts of sedimentation, deposition, and the sediment transport budget were reviewed for the same period. The results indicated that the sedimentation pattern did not change significantly compared to the current state, and the amount of the local sediment budget shown in the present state was slightly less. And there has been a local increase in the number of sediment budget transport, but there is no significant difference in the net and amount of sediment movements.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.394-398
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• 2016

Numerical analysis was conducted using Delft3D developed by Deltares in Netherlands to predict long-term river bed changes in Saemangeum Area. Tidal flow, discharge through the drainage gates and river bed changes in numerical model was verified by comparing to the results of field observation and hydraulic experiments. We calculated long-term river bed changes in Saemangeum area for 10 years from 2031 to 2040 after completion of development in Saemangeum. It is shown that 70 cm and 139 cm of accumulation occur in estuaries of Dongjin River and Mankyong River, respectively. Variation of flood level was also investigated considering long-term river bed changes. There was no change in estuary of Dongjin River but maximum flood level in estuary of Mankyong River increased 81 cm.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.337-340
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• 2008

The gate expansion was planed to increase discharge capacity of gate structure at sea dike in Asan Bay. So it was estimated for changing of hydraulic states in Pyeongteak Harbor Zone caused by gate expansion, by 2D and 3D CFD Module. In result, influence of gate expansion was less than tidal current and discharge ratio between old gate and new gate was 4:6.

• Advances in Computational Design
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• v.3 no.4
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• pp.319-338
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• 2018

High-performing architecture should be designed by taking into account the mutual dependency between the new building and the local context. The performative architecture plays an important role to avert any unforeseen failures after the building has been built; particularly ones related to the microclimate impacts that affect the human comfort. The use of the concept of solar envelopes helps designers to construct the developable mass of the building design considering the solar access and the site obstruction. However, the current analysis method using solar envelopes lack in terms of integrating the detailed information of the existing context during the simulation process. In architectural design, often the current site modelling not only absent in preserving the complex geometry but also information on the surface characteristics. Currently, the emerging applications of point clouds offer a great possibility to overcome these limitations, since they include the attribute information such as XYZ as the position information and RGB as the color information. This study particularly presents a comparative analysis between the manually built 3D models and the models generated from the point cloud data. The modelling comparisons focus on the relevant factors of solar radiation and a set of simulation to calculate the performance indicators regarding selected portions of the models. The experimental results emphasize an introduction of the design approach and the dataset visibility of the 3D existing environments. This paper ultimately aims at improving the current architectural decision of support environment means, by increasing the correspondence between the digital models for performance analysis and the real environments (context of design) during the conceptual design phase.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.127-133
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• 2018

The Saemangeum master plan includes dredging and waterproofing materials, construction projects that can change the hydraulic characteristics of the Saemangeum and Mangyeong and Dongjin River basins. In this study, the river safety of 2030 when the Saemangeum master plan was completed for 100 year frequency, 500 year frequency and 100 year frequency applied RCP 8.5 scenario was examined using Delft3D. As a result of the analysis, it was confirmed that there was no overflowing point at the 100 year frequency, but the difference between the flood level and the river bank elevation was relatively small at the curved and river joint part. At the 100-year frequency with the 500-year frequency and the RCP 8.5 scenario, the possibility of overflowing at several locations was confirmed. The possibility of river bed loss due to fast velocity appears in the upstream part of Mankyung River and it is necessary to monitor the safety of hydraulic structures continuously. In addition, it is expected that the expansion of the area showing the characteristics of the lake due to dredging will affect the sediment mechanism and water quality, so detailed and diverse studies will be needed.

• 한국전산유체공학회:학술대회논문집
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• 2002.05a
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• pp.140-145
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• 2002

The purpose of this 3-D numerical simulation is to calculate and examine a 500 kW Horizontal Axis Wind Turbine (HAWT) power performance and compare to calculation data(BEM method) from Delft University. The experimental approach, which has been the main method of investigation, appears to be reaching its limits, the cost increasing relate with the size of wind turbines. Hence, the use of Computational Fluid Dynamics (CFD) techniques and Navier-Stokes Solvers are considered a very serious contender. We has used the CFD software package CFX-TASC flow as a modeling tool to predict the power performance of a wind turbine on the basis of its geometry and operating data. The wind turbine with 40m diameters rotor, it was scaled to compare with the calculation data from delft university. The HAWT, which has eight-rpm variations are investigated respectively. The pitch angle is $+0.5^{\circ}$ and wind speed is fixed at 5m/s. The tip speed ratio (TSR) of the HAWT ranging from 2.89 to 9.63.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.219-219
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• 2021

서해안 중부 아산만 안쪽에 위치하는 평택·당진항에서 장래 개발 예정인 면적 6.9km²의 내항2공구 수역은 내항2공구 외곽호안 - 내항가호안 - 내항2공구 중앙 분리호안으로 둘러싸여 있으며, 투수성 제체인 내항가호안 사석 공극을 통하여 해수가 유통되어 조석 현상이 나타나고 있다. 2020년 8~9월의 2개월간 내항2공구 외곽호안 내·외측에서 조석 관측 결과, 2공구 수역의 최대 조차는 1.97m로서 외측 해역 최대 조차 9.79m의 20.1%이고 내·외측의 순간 수위차는 최대 5.82m에 달한다. 내항가호안은 내항2공구 개발이 거의 완료되는 시기까지 유지될 예정이므로 2공구 개발에 따른 내측 조차와 내·외측 수위차의 변화를 정확하게 예측하는 것은 내항가호안 제체 안전에 매우 중요하다. 이 연구의 목적은 장래 개발단계별 변화 예측에 앞서, 관측이 이루어진 2개월간의 실시간 내측 조석과 내·외측 수위차 시계열을 Delft3D-Flow를 이용하여 기 구축된 아산만 수치모델에서 재현하는 것이다. 내항가호안 제체 통과 유량은 내·외측 수위차에 비례하는 것으로 가정하고, 수위차 - 유량 관계식을 도출하였다. 수위차는 평택 조위관측소와 내항2공구 수역의 1분 간격 관측 조위로부터 산출하였고, 제체 통과 유량은 내측 조위(z, 평택항 DL 기준, m) - 수용적(V, 10⁶m³) 관계식으로 계산하였다. 내측 조위 - 수용적 관계식은 수심측량 성과로부터 V = 0.28z² + 3.73z + 2.96 (r²=1.00)으로 얻어졌다. 다양한 함수식의 적합성을 검토한 결과, 다음과 같은 수위차(𝚫z, m) - 제체 통과 유량(Q, m³/s) 관계식을 도출하였다. [내항가호안 내측으로 유입시] $Q_{IN}=\{\begin{array}{lll}{\exp}\{0.54\;{\ln}({\Delta}z)+6.00\}&&\text{; }{\Delta}z{\leq}1.8\\219.82{\Delta}z+158.56&&\text{; }{\Delta}z>1.8\end{array}\;\;(r^2=0.86)$ [내항가호안 외측으로 유출시] Q_OUT = -exp{0.44 ln(-𝚫z) + 5.70} (r²=0.59) 매 𝚫t 마다 제체 통과 유량을 계산하는 알고리즘을 Delft3D 소스 코드에 추가하고, 8개 분조 합성조석(M₂, S₂, K₁, O₁, N₂, K₂, P₁, Q₁)을 외력조건으로 설정하여 2개월간 조석 수치모델링을 수행하였다. 내항2공구 수역의 매 시별 조위 관측치와 모델치를 비교한 결과, 오차는 -0.37~0.37m의 범위이고, 오차 평균은 0.02m, 절대오차 평균은 0.08m로 상당히 정확하게 실시간 조위 변동을 모의하였다. 보정·검정된 이 모델을 이용하여 향후 내항2공구 개발에 따른 내측 조석과 내·외측 수위차 변화에 대한 예측모의를 진행할 예정이다.

• Ecology and Resilient Infrastructure
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• v.1 no.1
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• pp.8-18
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• 2014

This study analyzes characteristics of flow using 3 dimensional numerical model, Delft3D, at the downstream of hydraulic structure. And fish shelters are suggested by analyzing them in flood time. A hydraulic structure changes flow conveyance, water depth and velocity affecting the activity of the fish. Flow depth decreases and velocity is fast near the left bank at the downstream of Gumi weir because of the concentration of flow due to it. Therefore, fish shelters are generated near the right bank of it. As a result of vertical velocity distribution which indicates the range of fish activity, maximum value are 0.0043 m/s in 30-year of return period of flood 0.0052 m/s in 50 year flood, 0.0046 m/s in 80-year of return period of flood, and 0.0039 m/s in 100-year of return period of flood. As the discharge increases, the areas of fish shelters decreases because depth and turbulent energy increase according to increases discharge. The estimated areas of fish shelters near the right bank decrease from 61.5% in 30-year of return period of flood to 39.0% 100-year of return period of flood. Therefore, the constructed hydraulic structures affect fish shelters.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.309-314
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• 2004

Static and transient behaviour of Low Temperature Poly-Si TFTs (LTPS-TFTs) and Single Grain TFTs (SG- TFTs) are compared 3-D simulation is applied here for the first time to TFTs to account for the structure and twin boundaries in SG-TFTs.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.245-245
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• 2021

해양으로 유출된 5 mm 이하의 크기로 분해된 미세플라스틱이 해양 환경 오염의 주요 원인으로 자리잡았다. 최근에는 청정해역으로 알려진 남극해에서도 발견되고 있어 남극해에 잔류하는 미세플라스틱 오염 수준을 이해하기 위해 노력하고 있다. 하지만, 파랑의 효과를 고려한 남극해의 해수 순환 구조와 미세플라스틱의 고유 특성을 반영한 미세플라스틱의 거동 및 공간적 분포에 대한 복합적 이해는 상대적으로 부족하다. 남극해에서 발견된 미세플라스틱은 과학기지들의 방류수나, 조사선 등과 같은 인위적인 활동으로 인해 집적될 수 있으며, 특히 영구적으로 거주하는 과학기지에서 흘려보내는 방류수에 포함된 미세플라스틱은 과학기지 주변 해수 오염에 직접적인 영향을 줄 것으로 예상된다. 따라서, 본 연구에서는 파랑 효과에 따른 남극 킹조지 섬(King George Island)에 위치한 세종과학기지의 방류수에 포함된 미세플라스틱의 이송에 대해 모의하였다. 세종과학기지가 위치한 킹조지 섬과 넬슨 섬(Nelson Island) 사이의 멕스웰 만(Maxwell Bay)의 해수 흐름을 재현하기 위하여 해수 유동 모델(Delft3D-FLOW)이 사용되었다. 또한, 해수 유동 모델에 파랑 모델(Delft3D-WAVE)을 결합하여 파랑의 효과가 미세플라스틱의 이송에 미치는 영향을 확인하였다. 세종과학기지의 방류수가 흘러나가는 마리안 소만(Marian Cove)의 유속장을 바탕으로 이송, 확산, 입자의 침강 속도를 고려하여서, 세종과학기지에서 밀물 시 방출한 입자를 라그랑지안 입자 추적(Lagrangian Particle Tracking) 방법을 이용해 추적하였다. 해수의 밀도보다 가벼운 플라스틱의 경우 해수 표층의 흐름을 따라 소만 내부로 이송되어 해안선에 도달하고, 해수의 밀도보다 무거운 플라스틱의 경우 소만 내부로 이송되나 입자의 침강 속도로 인해 방출 위치 근처에서 집적된다. 파랑의 효과를 고려하게 되면, 고려하기 전보다 두 종류의 미세플라스틱 모두 소만 내부로 더 멀리 이송되는데, 이는 파랑으로 인한 힘(wave-induced force)이 해수 유동 모델의 운동방정식에 추가되며 파랑 에너지 분산으로 인해 해수 흐름에 변화를 준 것으로 보인다.