http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
남보우(Bo Woo Nam),홍사영(Sa Young Hong),성홍근(Hong Gun Sung),김종욱(Jong-Wook Kim),이재훈(Jaehoon Lee) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
This paper presents a numerical study on towing stability of barges. Towing simulations are carried out by using two different numerical models(MMG model and Cross-Flow model). Stability criteria are also suggested based on the analysis of the linearized governing equations for towed vased motion. In order to validate present nurreical model,s experimental data of Yasukwa et al.(2006) are used Single and double barges are simulated under the constant towing speed and direction conditions. Time histories of heading angle yaw rate and towline tension are compared between numerical results and experiments. The effects of towline length on slewing frequency and maximum heading angle are also observed. Though these calculation,s applicability of two numerical models in towing, stability analysis are studied.
풍하중에 의한 바지선의 예인 시 거동특성 변화에 관한 연구
남보우(Bo Woo Nam),최영명(Young-Myoung Choi),홍사영(Sa Young Hong) 한국해양공학회 2015 韓國海洋工學會誌 Vol.29 No.4
This paper presents the results of a numerical study on the towing characteristics of a barge under various wind conditions. First, stability criteria, including the wind force, were derived based on the linear motion equations of a towed vessel. The effect of the wind force on the towing stability was investigated using stability criteria. Next, towing simulations were carried out using a nonlinear time-domain simulation method. In this case, the towline was modeled as a simple spring-damper, and the wind force was computed using the wind coefficient from CFD calculations. Simulations were conducted for a barge under a constant towing speed and constant wind speed conditions. The effect of the wind direction on the slewing motion was also observed. In addition, a series of numerical simulations using variable wind speeds were performed for the present barge with and without a skeg.
남보우(Bo Woo Nam),박지용(Ji Young Park),홍사영(Sa Young Hong),성홍근(Hong Gun Sung),김종욱(Jong-Wook Kim) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.1
This paper presents the results of a numerical study on the towing stability of barges. Towing simulations were carried out by using two different numerical models (MMG model and cross flow model). Stability criteria are also suggested based on the analysis of the linearized governing equations for towed vessel motion. In order to validate the present numerical models, the experimental data of Yasukawa et al. (2006) were used. Simulations were conducted for single and double barges under constant towing speed and direction conditions. The time histories of the heading angel, yaw rate, and towline tension were compared between the numerical results and experiments. The effects of the towline length on the slewing frequency and maximum heading angle were also observed. In addition, a series of numerical simulations using variable hydrodynamic coefficients were performed to investigate the effects of the hydrodynamic forces on the towing stability.
Heave Compensator를 고려한 파랑 중 해상 크레인 설치작업 수치해석
남보우(Bo-Woo Nam),홍사영(Sa-Young Hong),김종욱(Jong-Wook Kim),이동엽(Dong-Yeop Lee) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.1
In this study, a numerical analysis of offshore installation using a floating crane with heave compensator is carried out in time domain. The motion analysis of crane vessels is based on floating body dynamics using convolution integral and the crane wire is treated as simple spring. The lifted structure is assumed as a rigid body with 3 degree-of-freedom translational motion. The heave compensator is numerically modelled by the generalized spring-damper system Firstly, forced motion simulations of crane wire system are carried out to figure out the basic principle of heave compensator. The transfer junction of crane wire system is obtained and effective wave period of heave compensator are found. Then, coupled analysis of crane vessel, crane wire, and lifted structure are performed in regular and irregular sea conditions. Two different crane vessels and two lifted structures (suction pile and manifold) are considered in this study. Through a series of numerical calculations, the effective zone of heave compensator is investigated with respect to wave period and crane wire length.
하이브리드 기법을 이용한 고정된 해양구조물에 작용하는 파랑하중에 관한 수치 시뮬레이션
남보우(Bo-Woo Nam),홍사영(Sa Young Hong),김용환(Yonghwan Kim) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.6
In this paper, the diffraction problems for fixed offshore structures are solved using a hybrid scheme. In this hybrid scheme, potential-based solutions and the Navier-Stokes-based finite volume method (FVM) with a volume-of-fluid (VOF) method are combined. We introduce a buffer zone for efficient wave-making and damping. In this buffer zone, the near field solution from FVM-VOF is gradually changed to Stokes' 2nd order wave solutions. Three different models, including the truncated cylinder, sphere, and wigleyⅢ model, are numerically investigated in regular waves with a wave steepness of 1/30. The efficiency and accuracy of the hybrid scheme are numerically validated from results using different domain sizes and buffer zones. The wave exciting forces from the FVM-VOF simulations are compared with experiments and potential-based solutions from the higher-order boundary element method (HOBEM). This comparison shows good agreement between the hybrid scheme and potential-based solutions.
복수 크레인을 이용한 침몰 선박 인양 작업에 관한 수치 시뮬레이션 연구
남보우(Bo Woo Nam),김정석(Jeong-Seok Kim),서민국(Min-Guk Seo),홍사영(Sa Young Hong),최혁진(Hyuek-Jin Choi) 한국해양환경·에너지학회 2021 한국해양환경공학회 학술대회논문집 Vol.2021 No.5
본 연구에서는 연안에서 빈번하게 활용되는 복수 해상 크레인을 이용한 침몰 선박 인양 작업에 대한 수치 시뮬레이션 연구를 수행하였다. 침몰 선박의 인양은 크게 3가지 단계, 즉 해저면으로부터 침몰선이 이탈하는 단계, 수중에서 수면까지 올려지는 단계, 수면 위로 떠올라 인양되는 단계로 구분될 수 있다. 본 연구에서는 이러한 작업에 대한 수치 시뮬레이션을 위하여 각 단계별로 침몰선박에 작용하는 파도, 바람, 조류 등에 의한 다양한 환경 외력과 해저면 이탈력, 부력 변화에 대해 수치 모델을 도입하여 모사하였으며, 두 대의 해상 크레인선이 근접 배치된 상황에서의 동유체역학적 상호작용 효과를 고려한 다수 부유체 운동 모델을 적용하였다. 개발된 수치 시뮬레이션 모델은 복수 크레인 인양 작업에 대한 수조 모형시험 결과와 비교하여 검증을 수행하였으며, 다양한 조건에서의 침몰 선박 인양 작업 시뮬레이션을 수행하여 침몰선 인양력에 미치는 다양한 환경 인자에 대한 영향을 검토하였다. In this paper, numerical simulations were conducted for the lifting operation of a sunken ship using multiple offshore cranes. The lifting operation for a sinking ship can be divided into three major stages: departure from the sea floor, lifting from the seabed to the sea surface, and lifting above the sea surface in the air. In this study, various numerical models were introduced to consider the environmental forces by wave, wind and current, seabed reaction forces and buoyancy change during the lifting operations. The motions of the multiple floating crane vessels were solved based on Cummins equation considering the effect of the hydrodynamic interactions. The developed numerical code was validated by comparing the results of model test and the sensitivity studies were carried out regarding the effect of various parameters on the lifting forces.
직교 격자계 기반 유동해석기법을 이용한 해양구조물에 작용하는 파랑하중 해석
남보우(Bo Woo Nam),양경규(Kyung Kyu Yang),김용환(Yonghwan Kim),성홍근(Hong Gun Sung),홍사영(Sa Young Hong) 한국해양환경·에너지학회 2012 한국해양환경·에너지학회 학술대회논문집 Vol.2012 No.5
This paper presents a numerical study of wave loads acting on offshore structures using a Cartesian-grid based flow simulation method. Finite volume discretization with volume-of-fluid(VOF) method is adopted to solve two-phase Namer-Stokes equations. Among many variations of VOF method, CICSAM scheme is applied. Body boundary conditions are satisfied using porosity function and wave generation is carried out by using transient(wave or damping) Tone approaches. In order to validate the present numerical method, three different basic offshore structures including sphere, Pinkster"s barge, WigleyIII models are numerically investigated. Diffraction and Radiation problems are solved by the present numerical method. Wave exciting and drift forces from diffraction problems are compared with potential-based solutions. Added mass and wave damping forces from radiation problems are also compared with potential results. Comparison results are jenny good to show the validity cf the present numerical method.
남보우(Bo-Woo Nam),홍사영(Sa-Young Hong),김병완(Byoung-Wan Kim),이동엽(Dong-Yeop Lee) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.1
A coupled analysis of a floating crane barge with a crane wire and hanging structure is carried out in thetime domain. The motion analysis of the crane barge is based on the floating multi-body dynamics, and thecrane wire is modeled as a simple spring tension. The hanging structure is assumed to be a rigid body with 3 degree-of-freedom translational motion. In this study, numerical simulations were conducted at three different stages. First, the developed code was validated by comparing the time-domain motion response of a crane barge with the frequency-domain results. Then, a coupled analysis of a crane barge and simple structure hanging by the crane wire was performed using the present scheme. The motion response and wire tension from the present calculations are compared with the results of OreaFlex. The agreement between the two sets of results isfairly good. Last, lowering simulations in regular and irregular waves were conducted considering buoyancy changes in the hanging structure. The effects of the wave conditions, structure’s weight, wire length, and lowering speed on the wire tension are considered.
운송 바지선의 예인안정성에 관한 모형시험 및 수치해석 연구
남보우(Bo Woo Nam),홍사영(Sa Young Hong),김진하(Jin Ha Kim),최성권(Sung Kwon Choi),김종욱(Jong-Wook Kim) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.2
This paper presents the results of an experimental and numerical study on the towing characteristics of a barge. A series of model tests were carried out at the Ocean Engineering Basin of KRISO. A model with a 1:50 scale ratio was constructed out of wood. First, force coefficient test were performed in order to obtain the surge, sway, and yaw force coefficients of the barge. The focus was the effect of skeg on the force coefficients. The stability parameter was calculated from the force coefficients. Next, towing tests in calm sea were carried out with different towline lengths and towing speeds. The trajectories of the barge and the towline tensions were measured during the tests. The measured trajectories were compared with numerical simulation results using a cross-flow model. The towing stability of the barge in a calm sea is discussed in detail.