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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
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Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 47, Issue 6 - Dec 2010
Volume 47, Issue 5 - Oct 2010
Volume 47, Issue 4 - Aug 2010
Volume 47, Issue 3 - Jun 2010
Volume 47, Issue 2 - Apr 2010
Volume 47, Issue 1 - Feb 2010
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A Study of using Wall Function for Numerical Analysis of High Reynolds Number Turbulent Flow
Choi, Jung-Kyu ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 647~655
DOI : 10.3744/SNAK.2010.47.5.647
In this paper, a numerical study is carried out for super-pipe, flat plate and axisymmetric body flows to investigate a validity of using wall function and high
in calculation of high Reynolds number flow. The velocity profiles in boundary layer agree well with the law of the wall. And it is found that the range of
��which validated the logarithmic law of the wall grows with increasing Reynolds number. From the result, an equation is suggested that can be used to estimate a maximum
value of validity of the log law. And the slope(1/
) of the log region of the numerical result is larger than that of experimental data. On the other hand, as
is increasing, both the friction and the pressure resistances tend to increase finely. When using
value beyond the range of log law, the surface shear stress shows a significant error and the pressure resistance increases rapidly. However, when using
value in the range, the computational result is reasonable. From this study, the use of the wall function with high value of
can be justified for a full scale Reynolds number ship flow.
Investigation for the Characteristics of Cavitation Modeling for Computational Fluid Dynamics
Park, Sun-Ho ; Rhee, Shin-Hyung ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 657~669
DOI : 10.3744/SNAK.2010.47.5.657
Cavitation is one of the most difficult physical phenomena to understand and predict. Many experimental and computational studies have been conducted for better understanding of the phenomenon. Recently, with the rapid development of computing hardware capacity and numerical methods, considerable advancement is observed in prediction of cavitation using computational fluid dynamics. To that end, many cavitation models have been developed and reported. In the present paper, some of the distinguished cavitation models are categorized and reviewed in terms of the computational frame work and formulation of transport equations. Then those characteristics are compared with each other.
A Study on the Bow Hull Form Design of Full Ship Considering the Nonlinear Waves
Yu, Jin-Won ; Lee, Young-Gill ; Choi, Si-Young ; Choi, Young-Chan ; Jeong, Kwang-Leol ; Ha, Yoon-Jin ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 671~679
DOI : 10.3744/SNAK.2010.47.5.671
This paper introduces a new hull form design method for the bow of a full ship, by actively applying the relation between the fore-body hull form and its wave resistance characteristics. For the hull form design, the Series 60(
) hull is chosen as the parent ship, and Kracht's charts are used to determine the parameters of the bulbous bow in the early stages of hull form design. Several hull forms have been tested in order to obtain enough hull form variations with various bow shapes and design parameters in the search of the best design. In order to investigate the resistance characteristics of the designed hull forms, numerical simulations with corresponding model tests have been rigorously performed. For the numerical simulations, the Marker-density method is employed to track the nonlinear phenomena of the free surface(program IUBW). Model tests have also been performed to achieve an improved research performance using the designed hulls. Both numerical and experimental results show that the wave resistance of the hull forms can be effectively diminished if the bows are designed using the method introduced in this research. It is also expected that this research can facilitate better productivity in hull form design, especially at the preliminary design stage of a full ship type vessel.
Estimation of Acceleration Response of Freefall Lifeboat using FSI Analysis Technique of LS-DYNA Code
Bae, Dong-Myung ; Zakki, A.F. ; Kim, Hag-Soo ; Kim, Joo-Gon ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 681~688
DOI : 10.3744/SNAK.2010.47.5.681
During certification of freefall lifeboats, it is necessary to estimate the injury potential of the impact loads exerted on the occupants during water entry. This paper focused on the numerical simulation to predict the acceleration response during the impact of freefall lifeboats on the water using FSI(Fluid-Structure Interaction) analysis technique of LS-DYNA code. FSI problems could be conveniently simulated by the overlapping capability using Arbitrary Lagrangian Eulerian(ALE) formulation and Euler-Lagrange coupling algorithm of LS-DYNA code. Through this study, it could be found that simulation results were in relatively good agreement with experimental ones in the acceleration peak values, and that the loading conditions were very sensitive to the acceleration responses by the experimental and simulation results.
A Study on the Resistance Performance of the Goose Neck Bulbous Bow by Numerical Simulation Method
Yu, Jin-Won ; Lee, Young-Gill ; Jeong, Kwang-Leol ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 689~696
DOI : 10.3744/SNAK.2010.47.5.689
Bulbous bow is one of the important design factors on the design of fore-body hull form. Using the interference technique of ship waves, the bulbous bow can decrease the wave resistance of ship. Recently, the goose neck bulb is applied mainly for high speed vessels like passenger ships and ferries etc.. Also, the goose neck bulb is applied for relatively high speed merchant vessels like container ships and LNG carriers. However, existing research papers about the goose neck bulb are not enough as reference data for the design of bow hull form. In this study, numerical calculations are carried out to investigate the bow wave characteristics of a high speed ferry with a normal high nose bulb or a goose neck bulb. By comparing the pressure distributions on the hull surface and the wave systems near the bow, the features of wave resistance reduction are discussed. Also, Numerical calculations were carried out for a series of goose neck bulbs to figure out the optimum bulb size. The maximum reduction rate of pressure resistance for the fore-body is achievable up to 8% by adopting the goose neck bulb in the present calculation.
Structural Analysis of the Bottom Plate of Small WIG Craft
Jeong, Han-Koo ; Nho, In-Sik ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 697~702
DOI : 10.3744/SNAK.2010.47.5.697
A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.
Structural Safety Evaluation of 40 Feet Sailing Yacht by Computational Structure Analysis
Ji, Sang-Hyun ; Roh, Ji-Sun ; Kang, Sung-Won ; Kim, Hyen-Woo ; Kim, Myung-Hyun ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 703~708
DOI : 10.3744/SNAK.2010.47.5.703
Recently, the development of the Marina port is determined as a national plan, and a variety of leisure boats and facilities on the field has been of critical interest. In particular, yachts are designed and produced mostly at small shipbuilding companies and research institute. The regulation and historic data, however, about the safety of structure are not readily available. Therefore, it is required to evaluate the strength of ship structure. This paper deals with the estimation of local strength of 40 feet sailing yacht by using finite element analysis. The forebody, mast and connection parts of a FRP yacht structure are evaluated. In addition, the results are compared with the regulation of Lloyd's register and Korean register.
Slenderness Ratio Distributions and Average Compressive Strengths of Stiffened Plates Used for In-Service Vessels
Nam, Ji-Myung ; Choung, Joon-Mo ; Jeon, Sang-Ik ; Lee, Min-Seong ; Ha, Tae-Bum ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 709~718
DOI : 10.3744/SNAK.2010.47.5.709
This paper deals with two contents: first, distributions of plate slenderness ratios, stiffened plate slenderness ratios, and stiffener slenderness ratios, which include dimensions and material variables of stiffened plates, of stiffened plates of large-sized in-service vessels, and, second, comparison of compressive strengths. The investigated vessels consist of 59 tankers, 49 bulkers, 28 product carriers, 15 container carriers, and 12 multi-purpose vessels. The tankers are ranged from handymax class to VLCC and larger than Suezmax class. The sizes of the bulkers are 20K to 200K deadweight. The maximum size of containers is less than 5000TEU class. Two parameters for normal distributions of the slenderness ratios (mean and standard deviation) are suggested and probable ranges of the slenderness ratios are also graphically presented. The ultimate strengths of the stiffened plates are presented using the various simplified formulas and nonlinear FEAs. As well, average compressive strength curves, which are necessary for the estimation of the hull girder moment capacities, are proposed. It is proved that formulas for stiffened plates in CSR overestimate slightly in overall average strain range. Mode5 formula (plate buckling mode) in CSR show unreasonably conservative results with respect to the ultimate strengths rather than post-ultimate average compressive strengths.
Development of an Evacuation Time Calculation Program for Passenger Ships Based on IMO Guidelines, MSC.1/Circ.1238
Choi, Jin ; Kim, Soo-Young ; Shin, Sung-Chul ; Kang, Hee-Jin ; Park, Beom-Jin ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 719~724
DOI : 10.3744/SNAK.2010.47.5.719
Thousands of passengers and crews are onboard a cruise ship and there are many cabins and large public spaces such as atria and theaters. Therefore it is easy to cause a huge loss of life and damage to property when accidents happen at sea. To improve the safety of passenger ships, in October 2007, IMO proposed MSC.1/Circ.1238 on guidelines for evacuation analysis and recommended its use. However, this guideline is difficult to apply because ship designers need to get many pieces of information from CAD drawings such as width and length of stairs and corridors and manually calculate the evacuation time. In this paper, for practical application of the guidelines, an evacuation time calculation program is developed using AutoCAD .NET API library and C Sharp language.
Development of On-Board Survival Time Estimation System for Ships and Naval Vessels
Hwang, Ho-Jin ; Gong, In-Young ; Lee, Gyeong-Jung ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 725~731
DOI : 10.3744/SNAK.2010.47.5.725
Damages of ships and naval vessels due to accidents and attacks would arouse enormous loss of lives and properties. To prevent maritime accidents is the best, and many researches have been achieved. But maritime accidents occurs continuously and to minimize casualties is considered as the second best. This paper has focused on the method and implementation of survival time estimation system for ships(STES system). The developed STES system provides plain and easy operations to get the survival time of damaged ship and naval vessel. The officers feed damaged conditions simply and quickly, and grasp instantly the survival time for damages. It would be attained by query and retrieval of survival time DB collected in a design process. We also check an effectivity of the system by practical applications.
Determination of the Optimal Operating Condition of the Hamworthy Mark I Cycle for LNG-FPSO
Cha, Ju-Hwan ; Lee, Joon-Chae ; Roh, Myung-Il ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 733~742
DOI : 10.3744/SNAK.2010.47.5.733
In this study, optimization was performed to improve the conventional liquefaction process of offshore plants, such as a LNG-FPSO(Liquefied Natural Gas-Floating, Production, Storage, and Offloading unit) by maximizing the energy efficiency of the process. The major equipments of the liquefaction process are compressors, expanders, and heat exchangers. These are connected by stream which has some thermodynamic properties, such as the temperature, pressure, enthalpy or specific volume, and entropy. For this, a process design problem for the liquefaction process of offshore plants was mathematically formulated as an optimization problem. The minimization of the total energy requirement of the liquefaction process was used as an objective function. Governing equations and other equations derived from thermodynamic laws acted as constraints. To solve this problem, the sequential quadratic programming(SQP) method was used. To evaluate the proposed method in this study, it was applied to the natural gas liquefaction process of the LNG-FPSO. The result showed that the proposed method could present the improved liquefaction process minimizing the total energy requirement as compared to conventional process.
A Study on Correlation of Dry Film Thickness with Multi-Nozzle Spray Pattern of Shop Primer
Yun, Won-Jun ; Choi, Min-Kyu ; Ro, Young-Shic ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 743~749
DOI : 10.3744/SNAK.2010.47.5.743
Multi-nozzle spray painting procedure of the inorganic zinc shop primer was established in order to obtain uniform film thickness. The shop primer paint prevents the corrosion of steel block during shipbuilding. When the dry film thickness of shop primer is insufficient, rust will be generated on the steel block. Otherwise, thick coating of shop primer may be a problem of weld defect. So, it is important to obtain the uniform film thickness of shop primer. The uniformity of dry film thickness is affected by spray speed, distance from spray gun to target surface and overlapping span of spray path. In order to uniformly maintain coating thickness of shop primer, the coating procedure was established based on the correlation of shop primer spray variables.
A Development of Remote Ship Maintenance System Based on Ship Area Network
Moon, Dae-Keun ; Bae, Jeong-Yeon ; Park, Jun-Hee ; Lee, Kwang-Il ; Kim, Hag-Bae ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 5, 2010, Pages 751~756
DOI : 10.3744/SNAK.2010.47.5.751
The rapid growth of IT technology has enabled ship automation systems to gain better functionality and safety with reduced costs and crew numbers. Nowadays, the remote maintenance services for the systems are required because a ship may be located in a very remote area. To provide the remote maintenance services, some issues such as how to collect the ship automation systems data, how to monitor a ship's data from onshore offices, how to get support from experts while sailing, and how to reduce the maintenance costs, should be addressed. In this paper, we propose a remote ship maintenance system for remote monitoring and diagnostics of ship automation systems, which is based on both a ship area network to integrate separate system networks and a ship-shore communication infrastructure to support a remote access using satellite communications. Finally, we present the function test to verify the applicability of the proposed system.