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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
Editor in Chief :
Volume & Issues
Volume 48, Issue 6 - Dec 2011
Volume 48, Issue 5 - Oct 2011
Volume 48, Issue 4 - Aug 2011
Volume 48, Issue 3 - Jun 2011
Volume 48, Issue 2 - Apr 2011
Volume 48, Issue 1 - Feb 2011
Selecting the target year
Study on the Resistance Improvement for an Extremely Full Ship Under CSR
Park, Hyun-Suk ; Kim, Tae-Hoon ; Oh, Se-Hyung ; Kim, Byoung-Nam ; Kim, Wu-Joan ; Yoo, Jae-Hoon ; Cho, Seong-Hoon ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 99~106
DOI : 10.3744/SNAK.2011.48.2.99
The appearance of CSR changes the concept of the hull form design as well as structural design, since the application of CSR inevitably brings the lightweight increase of a ship. Keeping the original design constraints such as principal particulars, deadweight, and speed performance, designers have to increase the volume of the hull form. As a result, the entrance angle at bow end should become larger, which results in blunter waterline shape. For a slow and full ship having high
more than 0.85, a new concept of bow shape has been required to alleviate the increase of wave-making resistance, since it is very difficult to improve waterline and frameline shape for such a full ship. In this paper a new bow shape of Capesize Bulk Carrier was developed to improve its wave-making characteristics without incompliance with the design constraints. For loading manual calculation, NAPA software was used. FLUENT6.3.26 and WAVIS1.4 were used to evaluate resistance performance of the subject hull forms. The newly designed hull form was tested at SSPA model basin for the final confirmation of resistance and propulsion performance of the ship. It was found that the new bow shape of a Capesize Bulk Carrier improved the resistance characteristics greatly compared to a conventional bulbous bow. The other benefits of new bow shape on the manufacturability were also investigated.
Flow Analysis of Two-Dimensional Floating Body with Moon Pool Using a Numerical Wave Tank
Koo, Weon-Cheol ; Lee, Kyoung-Rok ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 107~112
DOI : 10.3744/SNAK.2011.48.2.107
The aim of this study is to analyze the hydrodynamic properties of a 2D floating body with moon pool using a 2D fully nonlinear Numerical Wave Tank(NWT). This NWT was developed based on the Boundary Element Method(BEM) with potential theory and fully nonlinear free surface boundary conditions. Free surface elevations in the moon pool were calculated in the time domain for various frequencies of forced body motions. The added-mass and damping coefficients of the heaving body were also obtained. The present numerical results were compared with the analytic and experimental results and their accuracy was verified.
A Numerical Study for Design of a Fixed Type Fin Stabilizer Utilizing the Coanda Effect
Seo, Dae-Won ; Lee, Seung-Hee ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 113~120
DOI : 10.3744/SNAK.2011.48.2.113
Fins are widely used for roll stabilization of passenger ferries and high performance naval ships, among others. The Coanda effect is noticeable when a jet stream is applied tangentially to a curved wing surface since the jet can augment the lift by increasing the circulation. The Coanda effect has been found useful in various fields of aerodynamics and speculated to have practical applicability in marine hydrodynamics where various control surfaces are used to control motions of ships and the other offshore structures. In the present study, numerical computations have been performed to find proper jet momentum coefficients
and trailing edge shapes suitable for the application of the Coanda effect to a stabilizer fin. The results show that the lift coefficient of the modified Coanda fin at the zero angle of attack
identically coincides with that of the original fin at
when Coanda jet is supplied at the rate of
= 0.1. It is also shown that a fixed type fin stabilizer utilizing the Coanda effect can be implemented without changing the fin angle to actively control the motions of ships and the other offshore structures.
Localization of Underwater Noise Sources Using TDOA (Time Difference of Arrival) Method
Ahn, Byoung-Kwon ; Go, Yeong-Ju ; Rhee, Wook ; Choi, Jong-Soo ; Lee, Chang-Sup ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 121~127
DOI : 10.3744/SNAK.2011.48.2.121
As considerable interests in noise emission from a ship have been increased, the need for localization of noise sources of the marine propeller generating cavitation and singing noise is looming large. In many practical cases, cavitation and singing noise occur on a particular position of the certain blade of the propeller. It is so important to know the position of noise source correctly in order to eliminate or suppress unwanted noise. In this study, we develop "noise source localization technology" using TDOA method. Experimental measurements carried out at the circulating water channel and towing tank show that noise source can be clearly identified and localized using TDOA method.
PIV Measurements of Rudder Inflow Induced by Propeller Revolution in Hull Wake
Paik, Bu-Geun ; Kim, Ki-Sup ; Kim, Kyung-Youl ; Kim, Gun-Do ; Park, Young-Ha ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 128~133
DOI : 10.3744/SNAK.2011.48.2.128
In the present study, the flow fields in between the propeller and the semi-spade rudder are investigated by using PIV technique to find out the influences of both simulated hull wake and propeller wake on the incident flow to the rudder. The velocity fields are measured at the propeller rotation angle of
and the rudder deflection angles of
. Flow fields measured at each rudder deflection angle are analyzed in terms of angle-of-attack against the rudder leading edge. The hull wake increases the angle-of-attack more than that in the uniform inflow condition, forming the angle-of-attack of about
at 0.7R(R=propeller radius) position. The distribution of the angle-of-attack is strongly affected by the stagnation point around the leading edge and camber effect of the rudder. These effects provide asymmetric distribution of angle-of-attack with respect to the leading edge of the rudder.
Study on Resistance Performance of Icebreaking Cargo Vessel According to Variation of Thickness and Waterline Angle by Using Synthetic Ice
Shin, Byung-Chul ; Kim, Moon-Chan ; Lee, Seung-Ho ; Lee, Seung-Ki ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 134~140
DOI : 10.3744/SNAK.2011.48.2.134
The present paper deals with characteristics of resistance performance according to the variation of synthetic ice thickness and hull form. The resistance test has been conducted with pack ice condition in Pusan National University towing tank. Waterline angle has been chosen as a main parameter for the variation of hull form characteristics, which is the most important factor especially in icebreaking cargo vessel. The serial comparisons of resistance test have been done with the variation of hull form parameter as well as with the different thickness of synthetic ice. The different trend of resistance performances with increasing of waterline angle has been shown at each synthetic ice thickness. The present test results is expected to be confirmed by comparing the test results in ice tank in the near future.
Study on the Resultant Vorticity Numerical Model of the Propeller Wake
Park, Hui-Seung ; Yoon, Hyun-Sik ; Kim, Moon-Chan ; Chun, Ho-Hwan ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 141~146
DOI : 10.3744/SNAK.2011.48.2.141
This study numerically carried out the propeller open water test(POW) by solving Navier-Stokes equations governing the three-dimensional unsteady incompressible viscous flow with the turbulence closure model of the
SST model. Numerical simulations are performed at various range of advance ratios. Corresponding to Reynolds numbers of
based on free stream velocity and the chord length at 0.7 propeller radius. The present results give a good agreement with those of the experiment. The propeller induced vortical structures have been analyzed by visualizing the resultant vorticity. As the advance ratio increases, the magnitude and length of the resultant vorticity decrease significantly. As the main focus of present study, the numerical model to present the (
) plane-averaged resultant vorticity along the streamwise direction for various advance ratios has been suggested.
Development of a Numerical Method for the Evaluation of Ship Resistance and Self-Propulsion Performances
Kim, Jin ; Park, Il-Ryong ; Kim, Kwang-Soo ; Van, Suak-Ho ; Kim, Yoo-Chul ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 147~157
DOI : 10.3744/SNAK.2011.48.2.147
A RANS(Reynolds averaged Navier-Stokes) based numerical method is developed for the evaluation of ship resistance and self-propulsion performances. In the usability aspect of CFD for the hull form design, the field grid around practical hull forms is generated by solving a grid Poisson equation based on the hull surface grid generated from station offsets and centerline profile. A body force technique is introduced to model the effects of the propeller in which the propeller loads are obtained from potential flow analysis using an unsteady lifting surface method. The free surface is captured by using a two-phase level-set method and the realizable
model is used for turbulence closure. The hull attitude in vertical plane, i.e., trim and sinkage, is calculated by using a quasi-steady method and then considered in the computation by translating and rotating the grid system according to the values. For the validation of the proposed method, the numerical results of resistance tests for KCS, KLNG, and KVLCC1 and of self-propulsion test for KCS are compared with experimental data.
A Study on the Resistance Performance of Korean High-Speed Small Coastal Fishing Boat
Yu, Jin-Won ; Lee, Young-Gill ; Park, Ae-Seon ; Ha, Yoon-Jin ; Park, Cheong-Kyu ; Choi, Young-Chan ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 158~164
DOI : 10.3744/SNAK.2011.48.2.158
The study on the improvement of resistance performance is very important for coastal fishing boats in Korea, because the prices of fuel oil are gradually risen and the demand of high-speed fishing boats is increased lately. This study is concerned with the improvement of the resistance performance for Korean high-speed small coastal fishing boats. A semi-planing hull form of Korean small coastal fishing boat is selected in the role of initial hull. From the modification of the hull form parameters and the local characteristics of the hull form, the improvement of the resistance performance is achieved. The resistance performances of the initial and the modified hull forms are estimated by using a numerical simulation method. Also, ship model tests are carried out in ship model basin.
Wind Force Coefficients Computation of Gantry Crane by Wind Tunnel Experiment and Structural Analysis of the Crane
Lee, Jae-Hwan ; Kim, Tae-Wan ; Jang, In-Geun ; Han, Soon-Hung ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 165~170
DOI : 10.3744/SNAK.2011.48.2.165
In this paper, wind force coefficient by wind tunnel experiment is obtained to compute the accurate wind force of the gantry crane model to be used for mobile harbor ship. The first crane model was tested under 20, 30, 40, 52m/s, partially 58m/s and the wind force coefficient is about 2.0 which is very close to the suggested theoretical value. The other is the more reliable crane model and tested under 20, 30, 40m/s also giving the similar realistic wind force coefficient. Also structural analysis of crane model was performed giving the reliable stress level. Since the rolling effect is important for mobile harbor ship, the safety of the crane on the ship needs to be guaranteed. For this, using the computed reaction forces, a tie-down design is suggested which connects the crane and ship to resist the turnover motion of the crane.
On the Mechanical Properties at Low Temperatures for Steels of Ice-Class Vessels
Min, Dug-Ki ; Shim, Chun-Sik ; Shin, Dong-Wan ; Cho, Sang-Rai ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 171~177
DOI : 10.3744/SNAK.2011.48.2.171
Tensile tests were conducted at low temperatures for the steel materials which are used for outer shell of the vessels making transit through the polar regions. The selected steel materials were GL-DH32, GL-DH36 and GL-EH36. In comparison with the results at room temperature, the yield stress increases approximately by 10 to 13 percent at
and by 13 to 19 percent at
while the tensile strength increases about by 9 percent at
and 11 to 14 percent at
. To obtain true stress-true strain, i.e. correct plastic hardening characteristics, Bridgman's(1952) necking correction formula was introduced taking triaxial state of stresses after onset of diffuse necking into consideration. Photographs of fractured surfaces were taken by using Scanning Electron Microscope immedately after tensile tests completed and one for GL-EH36 has been presented in this paper.
A Study on the Optimum Design of Cargo Tank for the LPG Carriers Considering Fabrication Cost
Shin, Sang-Hoon ; Hwang, Sun-Bok ; Ko, Dae-Eun ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 178~182
DOI : 10.3744/SNAK.2011.48.2.178
Generally in order to reduce the steel weight of stiffened plate, stiffener spaces tend to be narrow and the plate gets thin. However, it will involve more fabrication cost because it can lead to the increase of welding length and the number of structural members. In the yard, the design which is able to reduce the total fabrication cost is needed, although it requires more steel weight. The purpose of this study is to find optimum stiffener spaces to minimize the fabrication cost for the cargo tank of LPG Carriers. Global optimization methods such as ES(Evolution Strategy) and GA(Genetic Algorithm) are introduced to find a global optimum solution and the sum of steel material cost and labor cost is selected as main objective function. Convergence degree of both methods in according to the size of searching population is examined and an efficient size is investigated. In order to verify the necessity of the optimum design based on the cost, minimum weight design and minimum cost design are carried out.
Experimental Study of Embedding Motion and Holding Power of Drag Embedment Type Anchor (DEA) on Sand Seafloor
Lee, Jae-Hoon ; Seo, Byoung-Cheon ; Shin, Hyunk-Young ;
Journal of the Society of Naval Architects of Korea, volume 48, issue 2, 2011, Pages 183~187
DOI : 10.3744/SNAK.2011.48.2.183
As larger the commercial vessel is, and rougher the marine environment becomes nowadays, drag embedment type anchor (DEA) of more stable performance and higher holding power is requested to be applied on the vessel. But, the performance of DEA has not become well known to academy and industries so far, that the basic study of DEA performance and holding force for the development of new DEA of higher performance is insufficient that required. In this paper, three types of same holding category DEA model (HALL, AC-14, POOL-N, scale 1/10), which are generally applied on the commercial vessel nowadays, were tested by being horizontally dragged on the test tank, on which sand was being floored with sufficient depth, and measured the holding force of each anchor simultaneously using load cell and D/A converter. With the test results, the embedding motion was analyzed to have three different stages and the holding force of each anchor was analyzed with respect to the anchor geometry, such as shape and weight of each type of anchors, and final embedding depth.