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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 49, Issue 6 - Dec 2012
Volume 49, Issue 5 - Oct 2012
Volume 49, Issue 4 - Aug 2012
Volume 49, Issue 3 - Jun 2012
Volume 49, Issue 2 - Apr 2012
Volume 49, Issue 1 - Feb 2012
Selecting the target year
Estimation of Resistance of Smart Harbor Crane Ship
Shin, Hyun-Kyoung ; Kim, Min-Su ; Jeong, Won-Jin ; Ha, Yong-Hwak ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 1~5
DOI : 10.3744/SNAK.2012.49.1.1
Recently, with increasing container ships` volume continuously, the conceptual design "Smart Harbor" of newly logistics processing system has been suggested. It is necessary to estimate resistance and horsepower for the selection of an appropriate propulsor at the initial design stage of Smart Harbor. In this study, CFD and the circulating water channel of the University of Ulsan are employed for estimating the resistance of the Smart Harbor Crane Ship with 1/100 scaled model. Two turbulent models are used. One is realizable k-
and the other is Reynolds stress turbulence model. In addition, the effects of the change in y+ and the number of meshes are considered during analysing.
Experiments and Numerical Validation for FPSO Bow Water Shipping
Lim, Ho-Jeong ; Lee, Hyun-Ho ; Park, Sun-Ho ; Rhee, Shin-Hyung ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 6~13
DOI : 10.3744/SNAK.2012.49.1.6
As ocean resources in shallow water areas are being exhausted, deep sea development is becoming common these days. Therefore floating type offshore structures are more competitive than fixed type structures, and FPSO is the most popular one these days. FPSO`s are generally operated in a specific region and positioned to meet mostly head or bow waves in order to reduce roll motions. However this makes these vessels more vulnerable to green water around the bow region, and therefore the bow shape must be properly designed to mitigate green water damage. In the present study, experimental results for three different FPSO bow shapes in regular head waves were analyzed and compared to each other. Also CFD computations were carried out as a sample validation case for the database built for CFD code validation.
The Effect of the Turning Rate of the Pod Propeller on the Roll Control System of the Cruise Ship
Lee, Sung-Kyun ; Lee, Jae-Hoon ; Rhee, Key-Pyo ; Choi, Jin-Woo ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 14~25
DOI : 10.3744/SNAK.2012.49.1.14
Recently, the application and installation of the pod propeller to the cruise ship is dramatically increased. It is because pod propulsion system allows a lot of flexibility in design of the internal arrangement of a ship. To reflect this trend, many researches have conducted to use the pod propeller for the roll stabilization of a ship. In the paper, a roll stabilization controller is designed by using fins and pod propellers as the control actuators for cruise ships. Two kinds of control algorithms are adopted for the roll control system; LQR (Linear Quadratic Regulator) algorithm and frequency-weighted LQR algorithm. Through the numerical simulation, the effect of the turning rate of the pod propeller on the roll control system is analyzed. Analysis of the simulation results indicated that the turning rate of the pod propellers is one of the important parameters which give the significant effects on the roll stabilization.
Analysis of Viscous Flow Around an Impulsively Started Marine Propeller Using VIC(Vortex In Cell) Method
Lee, Jun-Hyeok ; Kim, Yoo-Chul ; Lee, Youn-Mo ; Suh, Jung-Chun ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 26~32
DOI : 10.3744/SNAK.2012.49.1.26
The 3-D unsteady viscous flow around an impulsively started rotating marine propeller is simulated using VIC(Vortex-In-Cell) method which is adequate to analyze the strong vortical flow around complicatedly-shaped body. The computational procedure is governed by the vorticity transport equation in Lagrangian form. In order to solve the equation, a regular grid which is independent to the shape of a body is introduced and each term of the equation is evaluated numerically on the grid by applying immersed boundary concept. In this paper, the overall algorithm including the formulation of governing equations and boundary conditions is described and some computational results are presented with discussing their physical validity.
Determination of the Optimal Operating Condition of Dual Mixed Refrigerant Cycle of LNG FPSO Topside Liquefaction Process
Lee, Joon-Chae ; Cha, Ju-Hwan ; Roh, Myung-Il ; Hwang, Ji-Hyun ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 33~44
DOI : 10.3744/SNAK.2012.49.1.33
In this study, the optimal operating conditions for the dual mixed refrigerant(DMR) cycle were determined by considering the power efficiency. The DMR cycle consists of compressors, heat exchangers, seawater coolers, valves, phase separators, tees, and common headers, and the operating conditions include the equipment`s flow rate, pressure, temperature, and refrigerant composition per flow. First, a mathematical model of the DMR cycle was formulated in this study by referring to the results of a past study that formulated a mathematical model of the single mixed refrigerant(SMR) cycle, which consists of compressors, heat exchangers, seawater coolers, and valves, and by considering as well the tees, phase separators, and common headers. Finally, in this study, the optimal operating conditions from the formulated mathematical model was obtained using a hybrid optimization method that consists of the genetic algorithm(GA) and sequential quadratic programming(SQP). Moreover, the required power at the obtained conditions was decreased by 1.4% compared with the corresponding value from the past relevant study of Venkatarathnam.
A Measurement of Sea Ice Properties at Chukchi Borderland During the Summer
Jeong, Seong-Yeob ; Choi, Gul-Gi ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 45~51
DOI : 10.3744/SNAK.2012.49.1.45
Sea ice properties have been considered a key indicator in the structural design criteria of icebreaking vessels and arctic offshore platforms to estimate design ice load and resistance for their safety management in Arctic Ocean. A measurement study of sea ice properties was conducted during July to August of 2011 with the Korean icebreaking research vessel "Araon" around Chukchi Borderland. The sea ice concentration appears to be rapidly decreasing during this cruise. Ice condition seems to be thick second-year ice and multi-year ice and then, a lot of melt ponds were observed in the surface of ice floe. Calculated flexural strength of sea ice was about 250~550kPa, ice thickness was roughly 1.3~3.0m. In this research we performed field experiment to measure ice temperature along the depth, thickness, density, salinity, brine volume ratio and crystal structure. Apparent conductivities derived with the electromagnetic induction instrument were compared to drill hole measurement results and accuracy of sea ice thickness estimation formula was discussed.
Experimental Study on Free Roll Decay Motions of a Damaged Ship for CFD Validation Database
Lee, Sung-Kyun ; You, Ji-Myoung ; Lee, Hyun-Ho ; Rhee, Shin-Hyung ; Rhee, Key-Pyo ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 52~59
DOI : 10.3744/SNAK.2012.49.1.52
Among many factors to be considered for higher safety level requirements, the hull stability in intact and damaged conditions in seaways is of utmost importance. Since the assessment of a damaged ship is complicated due to the highly non-linear behavior, it is widely acknowledged that computational fluid dynamics (CFD) methods are one of the most feasible approaches. Although many research activities are being reported on the damaged ship stability recently, most of them are not designed for validation of CFD studies. In this study, well-designed model tests were performed to build a CFD validation database, which is essential in developing better CFD methods for the damage stability assessment. The geometry of the damaged compartment and test conditions were determined based on preliminary CFD simulations. Free roll decay tests in calm water with both intact and damaged ships were performed and the roll motion characteristics were compared. The damaged ship showed a larger roll damping coefficient and more rapid decrease of roll amplitude than the intact ship. The primary reason of these efforts can be explained by the movement of the flooded water.
Study on Numerical Sensitivity and Uncertainty in the Analysis of Parametric Roll
Park, Dong-Min ; Kim, Tae-Young ; Kim, Yong-Hwan ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 60~67
DOI : 10.3744/SNAK.2012.49.1.60
This study considers the numerical analysis on parametric roll for container ships. As a method of numerical simulation, an impulse-response-function approach is applied in time domain. A systematic study is carried out for the parametric roll of two container ships, particularly observing the sensitivity of computational results to some parameters which can affect the analysis of parametric roll. The parameters to be considered are metacentric height (GM), simulation time window, and the discretization of wave spectrum. Based on the result of parametric roll simulation, numerical sensitivity and uncertainty in computational analysis are discussed.
Multi-floor Layout for the Liquefaction Process Systems of LNG FPSO Using the Optimization Technique
Ku, Nam-Kug ; Lee, Joon-Chae ; Roh, Myung-Il ; Hwang, Ji-Hyun ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 68~78
DOI : 10.3744/SNAK.2012.49.1.68
A layout of an LNG FPSO should be elaborately determined as compared with that of an onshore plant because many topside process systems are installed on the limited area; the deck of the LNG FPSO. Especially, the layout should be made as multi-deck, not single-deck and have a minimum area. In this study, a multi-floor layout for the liquefaction process, the dual mixed refrigerant(DMR) cycle, of LNG FPSO was determined by using the optimization technique. For this, an optimization problem for the multi-floor layout was mathematically formulated. The problem consists of 589 design variables representing the positions of topside process systems, 125 equality constraints and 2,315 inequality constraints representing limitations on the layout of them, and an objective function representing the total layout cost. To solve the problem, a hybrid optimization method that consists of the genetic algorithm(GA) and sequential quadratic programming(SQP) was used in this study. As a result, we can obtain a multi-floor layout for the liquefaction process of the LNG FPSO which satisfies all constraints related to limitations on the layout.
An Experimental Study on the Effects of Bow Flare Angle about Green Water in Regular Waves
Ha, Yoon-Jin ; Lee, Young-Gill ; Jeong, Kwang-Leol ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 79~86
DOI : 10.3744/SNAK.2012.49.1.79
It is very important to investigate and understand the motion of a FPSO on waves because green water phenomenon occurs owing to the relative motions between incident waves and a ship on them. In this research, both experimental and some numerical approaches have been performed in head sea conditions with regular waves. As an object model of this research, a FPSO model is set free to heave and pitch during the experiments. Also, the motions of the FPSO model which are the results of the experiments are used for the corresponding numerical computations. The purpose of this study is to clarify the effect of bow flare on green water load. In this research, it is found that the amount of green water entered from the side of bow is decreased by the increase of bow flare angle. Moreover, the relation between the green water on the bow upper deck and the impact load on the vertical wall located at turrethead is investigated. The results of this research could be used as one of the fundamental data to design bow flares. Also, an optimized bow flare angle is proposed in this study.
A Prototype of Sensor Module to Control the Position of Hull Block for Tack Welding
Jeon, Jeong-Ik ; Lee, Jang-Hyun ; Son, Gum-Jun ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 87~92
DOI : 10.3744/SNAK.2012.49.1.87
Alignment of the main plates during the tack welding is essential to block assembly since most of the curved blocks and outfitting parts are assembled on the jigs and fixtures. Tact welding of main plates is the initial process of the curved hull block assembly. Due to the heavy weight of the main plates it is difficult to locate the plate on the accurate position of the jig and fixtures before welding. The conventional masonry process requires much time and manual work in order to achieve the accurate alignment. This labour-intensive process results in relatively high errors and correction works. Due to their larger dimensions and heavier weights, these hull blocks are not ergonomically desirable and, therefore, various mechanical devices such as hydraulic balancers or hydraulic jigs are used for the plate alignment. In this study, the position-sensing scheme implemented by sensors is presented in order to align the main plates on the accurate position during the hull block assembly. Integrating the Infrared photo sensors and micro processor unit, a small scaled prototype of the position-sensing module is developed to determine the alignment of main plates.
A Study on Shape Measuring Technique of a Yacht Sail
Kim, Choul-Hee ; Choi, Jung-Kyu ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 93~98
DOI : 10.3744/SNAK.2012.49.1.93
In this study, we introduced image processing technic to measure shape variations of general bodies and applied it to the flexible yacht sail. Shape measurements of simple bodies sails were carried out and results showed that technic can be a reliable method to measure shape variations of the flexible yacht sail. The sail shape variation of 30ft sloop type yacht sail is measured on different sailing conditions. As velocity and direction of wind are increased, trailing edges in the upper part of the sail become more open than the lower part of the sail which are not changed. So it is confirmed that the shape measurement of a sail shape depending on a sailing condition is possible to use image processing scheme.
An Experimental Study on Fatigue Life Evaluation of Welded Joints under Storm Loading
Yoo, Chang-Hyuk ; Kim, Kyung-Su ; Suh, Yong-Suk ; Shim, Yong-Lae ; Ha, Yeong-Su ; You, Won-Hyo ; Choi, Hyun-Jun ;
Journal of the Society of Naval Architects of Korea, volume 49, issue 1, 2012, Pages 99~108
DOI : 10.3744/SNAK.2012.49.1.99
In this paper, fatigue tests are conducted for the specimens with longitudinal and transverse attachment under variable amplitude axial loading based on storm model. Considered loadings include repeated single storm, 6 or 8 storms randomly, and storms including calm sea condition while the mean stress and the maximum stress of loadings are changed. The effect of three variables are investigated; root mean square(RMS) value of stress amplitude, mean stress shift and maximum stress, which can characterize storm loading on fatigue life. In addition, experiments including calm sea loading are also carried out to investigate the effect of calm sea state. Test results are evaluated and compared with DNV-CN2005 and Matsuoka`s method for the estimation of crack initiation and propagation life. To verify the validity of the criteria, the measured crack initiation lifes are compared with the specific crack length 15mm, which are calculated with beach marks.