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CEL기법을 이용한 앵커 끌림 시뮬레이션에 의한 Rock-berm 설계
신문범(Mun-Beom Shin),박동수(Dong-Su Park),서영교(Young-kyo Seo) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.6
In this study, an anchor dragging simulation was performed using the CEL method to design a rock-berm, which is a protection method for submarine cables. In order to simulate an anchor drag, preliminary simulations were first performed to determine the initial anchor penetration depth, anchor drag velocity, drag angle, and distance between the anchor and rock-berm. Based on the preceding simulation results, a safe rock-berm design for protecting the submarine cables was simulated to calculate the anchor penetration depth by the anchor dragging. As a result, the penetration depth of the anchor was found to be shallower in a hard seabed, and the penetration depth was deeper in a soft seabed. , the height of the rock-berm was determined according to the physical properties of the seabed.
해저지반 성질과 매설깊이 변화에 따른 해저파이프의 충돌 특성
신문범(Mun-Beom Shin),서영교(Young-kyo Seo) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.3
In this study, the impact characteristics of subsea pipelines that were installed in various soil types and burial depths were evaluated by a numerical method. An impact scenario replicated a dropped ship anchor that fell vertically and impacted an installed subsea pipeline. In order to calculate the impact force through terminal velocity, FLUENT, a computational fluid dynamic program and MDM (Moving Deforming Mesh) technique were applied. Next, a dynamic finite element program, ANSYS Explicit Dynamics, was used for impact analysis between the anchor and pipeline (or, subsea if they were buried). Three soil types were considered: loose sand, dense sand and soft clay by applying the Mohr-coulomb model to the seabed. The buried depth was assumed to be 0 m, 1 m and 2 m. In conclusion, a subsea pipeline was the most stable when buried in dense sand at a depth of 2 m to prevent impact damage.
Eun Kyo Ko,Han Gyeol Lee,Sangmin Lee,Junsik Mun,Jinkwon Kim,Ji Hye Lee,Tae Heon Kim,Jin-Seok Chung,Suk Bum Chung,Miyoung Kim,Seo Hyoung Chang,Tae Won Noh 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
In the field of oxide heterostructure engineering, there have been extensive efforts to couple the various functionalities of each material. The Berry curvature-driven magnetotransport of SrRuO3 ultrathin films is currently receiving a great deal of attention because it is extremely sensitive to extensive physical parameters. Although this is beneficial in terms of heterostructure engineering, it renders transport behavior vulnerable to nanoscale inhomogeneity, resulting in artifacts called “hump anomalies”. Here, we develop a method to tune the magnetotransport properties of SrRuO3 ultrathin films capped by LaAlO3 layers. We systematically controlled the kinetic process by varying the pressure during LaAlO3 layer deposition and investigated the effects on nanoscale inhomogeneity in SrRuO3 films. We found that the high-kinetic energy of the capping layer adatoms induces stoichiometric modification and nano-scale lattice deformation of the underlying SrRuO3 layer. The control of kinetics provides us a way to modulate magnetization and the associated magnetotransport of the SrRuO3 layer.
Shin, Mun-Beom,Seo, Young-Kyo Korean Society of Ocean Engineers 2017 Journal of advanced research in ocean engineering Vol.3 No.2
When an anchor is dropped into the sea, there exists a danger of collision on the pipeline and subsea cables in the seabed. This collision could cause huge environmental disasters and serious economic losses. In order to secure the safety of subsea structures such as pipelines and subsea cables from the external impact, it is necessary to estimate the exact external force through the anchor's terminal velocity on the water. FLUENT, a computational fluid dynamic program, was used to acquire the terminal velocity and drag coefficient computation. A half-symmetry condition was used in order to reduce the computational time and a moving deforming mesh technique also adapted to present hydrostatic pressure. The results were examined with the equation based on Newton's Second Law to check the error rate. In this study, three example cases were calculated by stockless anchors of 5.25 ton, 10.5 ton, and 15.4 ton, and for the onshore experiment dropped height was back calculated with the anchor's terminal velocity in the water.