유체충격력 예측을 위한 3차원 다상류 시뮬레이션의 응용

정세민(Se-min Jeong),황성철(Sung-Chul Hwang),박종천(Jong-Chun Park) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.2

In this study, the impact loads on tank walls by sloshing phenomena and on a tall structure in a three-dimensional rectangular tank were predicted using multiphase flow simulations. The solver was based on the CIP/CCUP (Constraint interpolation CIP/CIP combined unified procedure) method, and the THINC-WLIC (Tangent hyperbola for interface capturing-weighted line interface calculation) scheme was used to capture the airwater interface. For the convection terms of the Navier-Stokes equations, the USCIP (Unsplit semi-lagrangian CIP) method was adopted. The results of simulations were compared with those of experiments. Overall, the comparisons were reasonably good.

Mud Handling System 수송라인 내 혼상류 시뮬레이션을 위한 수치해법 개발

정세민 ( Jeong Se-min ),단명호 ( Duan Ming-hao ),박종천 ( Park Jong-chun ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.3

In the drilling processes and regarding systems, multiphase flows, where gas, water, oil and discrete solid materials are mixed, frequently and easily observed. To increase the performance and guarantee the safety of the whole system, it is of importance to predict and analyze the characteristics of these complicated flows. In this study, before applying to concerned problems, such as the flows in the mud pipeline and mud gas-liquid separator, two-dimensional numerical simulations for some typical multiphase problems were carried out by newly developed solver. The governing equations were discretized by FVM(Finite Volume Method) for general curvi-linear coordinate systems. THINC-WLIC (Tangent Hyperbola for Interface Capturing-Weighted Line Interface Calculation) scheme was used to capture the air-water interface. For the convection terms of Navier-Stokes equations, the MUSCL(Monotonic Upstream-Centered Scheme for Conservation Laws) with TVD(Total Variation Diminishing) scheme was adopted. Firstly, as a benchmark test, Rayleigh-Taylor instability was simulated. The results by present solver showed reasonably good with those of analytic solutions and by other numerical simulations. Then, bubble rising in a unbounded domain and in a bent pipe were simulated.

중첩격자계를 사용한 2차원 복수 물체주위 유동장의 수치 계산

정세민(Se-Min Jeong),이영길(Young-Gill Lee),이승희(Seung-Hee Lee) 한국전산유체공학회 1996 한국전산유체공학회 학술대회논문집 Vol.1996 No.-

In the present paper, flow fields around two dimensional single and two circular cylinders are analysed by a finite difference method. Navier-Stokes and the continuity equations are solved to simulate the flow fields. A overlapped grid system(the composite of a body boundary-fitted grid system near the body and a rectangular grid system for other flow fields) is used for this calculation. In the use of overlapped grid system, it is most significant thing to exchange the physical quantities from one grid system to the other one continuously. In this research, the linear interpolations of physical quantaties are done for this purpose in the overlapped region.<br/> The numerical calculations are carried out for the flows around a circular cylinder and two cylinders to verify the accuracy of present method. The flow fields around two cylinders facing the flow with side by side and tandem arrangement are analysed. The results are compared to other experimental and computational ones done in other single grid system.

CFD를 이용한 해면 효과익 주위의 유동특성에 관한 파라미터 연구

김이슬,정세민(Se-Min Jeong) 한국해양환경·에너지학회 2019 한국해양환경공학회 학술대회논문집 Vol.2019 No.11

한국인근 해양지중저장 중 누출된 CO₂의 다중규모 확산에 관한 수치적 연구

고석원(Seokwon Ko),정세민(Se-Min Jeong) 한국해양환경·에너지학회 2019 한국해양환경·에너지학회 학술대회논문집 Vol.2019 No.5

지구온난화를 완화시키기 위해 CO₂ 배출을 줄이는 CCS기술에 관한 연구가 전 세계적으로 진행되고 있다. 육상 저장 공간이 부족한 우리나라에서는 CCS기술 중 해양지중저장법이 실행 가능하다. 해양지중저장법의 실행을 위해서는 CO₂의 누출 위험도, 누출 모니터링과 누출 시의 환경 영향평가를 통한 공적 수용성(Public acceptance) 확보가 필요하며, 누출 시의 환경 영향 평가를 위해서는 누출된 기체상태의 CO₂ 거동과 용해된 CO₂(DCO₂, Dissolved CO₂)의 해수 중 확산 예측이 중요하다. 본 연구에서는 대한민국 인근 해양지중에 저장된 CO₂가 다양한 원인으로 해저면에서 해수로 누출되는 경우에 대한 CO₂의 다중확산을 MEC-CO₂ 모델을 이용한 수치시뮬레이션을 통해 예측하고, 환경영향 평가를 수행하였다. 연간 0.35, 0.5 및 1.0만톤의 누출량을 기준으로 15일간의 시뮬레이션을 수행한 결과 누출면(수심 180m)에서 80m 상승한 수심 100m에서는 모두 용해되는 것으로 예측되었다. 누출량이 가장 많은 경우에도 환경영향의 기준치로 선정한 CO₂ 분압(pCO₂, partial pressure CO₂) 변화량(ΔpCO₂)인 500ppm(Kita and Watanabe, [2006])을 초과하지 않았다. The CCS(Carbon Capture and Storage) technology to reduce CO₂ emission is internationally implemented for the mitigation of global warming. Since there is not enough inland storage space in Korea, ocean geological storage, is feasible. However. in order to carry out ocean geological storage, public acceptance should be acquired through the risk assessment of CO₂ leakage, the leakage monitoring and the assessment of environmental impact when CO₂ leakage occurs. The behavior of leaked gas or liquid CO₂, and the prediction of diffusion of dissolved CO₂(DCO₂) in seawater are important for the assessment of environmental impact. In this study, the multi-diffusion of leaked CO₂, purposely stored under the seabed near southeastern coast of Korea is predicted through the numerical simulation using MEC-CO₂, model, and is carried out the assessment of environmental impact. After 15days of leakage three different amounts of leaked CO₂, 0.0035, 0.005 and 0.01 million tons per year, it was predicted that all CO₂ bubbles, which were leaked at water depth of 180m, would be dissolved before reaching the free surface. Even for extreme case. the change of partial pressure CO₂(ΔpCO₂) did not exceed 500ppm, which was suggested by (Kita and Watanabe, [2006]) for quantitative environment impact.

입력 파랑 스펙트럼을 만족시키기 위한 수치 조파 기법

손보훈(Bo-Hun Son),정세민(Se-Min Jeong) 한국해양환경·에너지학회 2020 한국해양환경공학회 학술대회논문집 Vol.2020 No.11

파랑에 인해 고정 혹은 부유된 물체에 작용하는 충격력과 부유체의 운동 및 내항 성능 예측은 조선해양공학에서 중요한 주제로, 주로 실험적인 방법이나 포텐셜 기반의 해석적 방법으로 수행되어져 왔다. 하지만, 최근에는 CFD 기법과 컴퓨터 성능의 비약적인 발전으로 실험을 대체하여 수치조파수조(Numerical Wave Tank, NWT)를 활용하는 연구 또한 활발히 이루어지고 있다. NWT에서 중요한 것은 목적 파랑장(Wave-fields)을 효율적으로 정확히 구현하는 것으로, 파 형상의 수치 확산 최소화, 경계에서의 반사파 억제 등이 난제이며, 목적파(스펙트럼)에 맞는 최적의 격자비, 시간간격 등을 선정하는 것 또한 중요하다. 본 연구에서는 최근 조선해양분야의 유체관련 해석에 널리 사용되고 있는 상용 CFD SW인 Siemens 사의 STAR-CCM+를 사용하여 NWT를 구현할 때, 최적의 격자계 구성, 입력파 성분 수, 수치 기법 등을 찾아 입력파랑 스펙트럼을 만족시키는 파랑장을 재현하기 위한 파라미터 연구를 수행하였다. 파라미터의 변화에 의한 파랑장 변화를 분석하고, NWT내의 파랑의 시계열로부터 구한 파랑 스펙트럼을 입력 스펙트럼과 비교하여 그 정도를 확인하였다. The impact force acting on a fixed or floating body from waves and the motion and seakeeping performance of a floating body, are important topics in naval architecture and ocean engineering, and have been mainly performed by experimental methods or potential-based analytical methods. However, in recent years, researches using a Numerical Wave Tank (NWT) have been actively performed by replacing experiments owing to the rapid development of CFD techniques and computer performance. The important thing in NWT is efficiently and accurately to reproduce the target wave-fields, minimizing the numerical diffusion of the wave shape, suppressing the reflected wave at the boundary, etc. And selection of the optimal grid ratio and time-step size for the target wave are also important. In this study, a parameter study was carried out to find optimum grid system, the number of input wave components and numerical technique for reproducing the wave field that satisfies input wave spectrum when implementing NWT using Siemens" STAR-CCM+, a commercial CFD SW widely used to fluid-related analysis in the naval architecture and ocean engineering. The change of the wave field due to the change of parameter was analyzed, and the accuracy of the wave spectrum obtained from the time series of waves in the NWT was compared with the input wave spectrum to confirm the accuracy.

선미유동 제어용 수직판 제원 변화에 따른 유동특성 연구

김도정,오우준,박제웅,정세민,Kim, Do-Jung,Oh, Woo-Jun,Park, Je-Woong,Jeong, Se-Min 해양환경안전학회 2016 해양환경안전학회지 Vol.22 No.5

이산화탄소 배출량 제한을 의무화하는 EEDI, SEEMP 등의 국제협약에 대응하기 위하여 선박의 에너지 절감장치(ESD, Energy Saving Device) 관련 국내기술 대응이 절실하다. 본 연구는 국내 중소형 조선소의 주력선종 효율 향상의 ESD를 설계하기 위하여 유동특성 분석에 대한 연구이다. 프로펠러 상단으로 유입되는 유동을 개선하기 위하여 bare hull의 선미벌브 및 빌지 주변의 유동특성을 수치해석과 모형시험을 통하여 정성적으로 분석하였으며, 선저압력 지점의 개선 및 프로펠러 상단 유입의 선미 빌지 유동 제어를 위하여 선미벌브와 빌지 사이에 수직평판을 부착하였다. 선미 선체표면 압력회복으로 전저항이 약 3.04 % 감소하였으며, 프로펠러 상단 유동 제어를 통해 평균 공칭반류가 약 18.8 % 감소하였다. To cope with international regulations, such as Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and so forth, and to enforce limitations on $CO_2$ emissions, green-ship technology to lower fuel consumption has been actively researched, and the development of an energy-saving device (ESD) is being pursued. In order to design an ESD for small and medium-sized domestic vessels, an analysis on flow characteristics has been performed in the present study. Through a model test and numerical analyses, the characteristics of flow around the stern bilge and bulb have been compared to improve wake quality and resistance performance. As a result of these comparisons and analyses, a vertical plate has been adopted,, as a new ESD. Design criteria for the proposed ESD are also suggested. By applying this new ESD, it is expected that the total resistance and average nominal wake can be reduced by 3.04 % and 18.8 %, respectively.

경계성 난소종양 수술 시 우연히 발견한 충수돌기 유암

문윤진 ( Mun Yun Jin ),정세민 ( Jeong Se Min ),박승근 ( Park Seung Geun ),김민정 ( Kim Min Jeong ),백소야 ( Baeg So Ya ),박혜영 ( Park Hye Yeong ),윤여홍 ( Yun Yeo Hong ),지용헌 ( Ji Yong Heon ) 대한산부인과학회 2004 Obstetrics & Gynecology Science Vol.47 No.3

A case with carcinoid tumor of the appendix was encountered incidentally during an elective abdominal surgery for borderline mucinous ovarian tumor in a 16-year old female. Carcinoid tumor of appendix is the most common neoplasm of the gastrointestinal tract in childhood and adolesence. They are usually regarded as a benign neoplasm and an uncommon source of metastasis and recurrence. We report this case with reference to the value of grosss examination of the appendix and incidental appendectomy during gynecologic abdominal operations.

해양지중저장 중 누출된 이산화탄소의 해수중 거동 예측 및 환경영향 평가를 위한 시나리오 기반 수치 시뮬레이션

손보훈(Bo-Hun Son),정세민(Se-Min Jeong) 한국해양환경·에너지학회 2020 한국해양환경·에너지학회 학술대회논문집 Vol.2020 No.7

재해, 재난 시 인프라 간의 상호의존성을 고려한 전력계통 복귀력 평가

최운경(Woon-Kyeong Choi),정세민(Se-Min Jeong),최재석(Jae-Seok Choi),윤용범(Yong-Beum Yoon),이기백(Ki-Baek Lee) 대한전기학회 2018 대한전기학회 학술대회 논문집 Vol.2018 No.-