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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 53, Issue 4 - Aug 2016
Volume 53, Issue 3 - Jun 2016
Volume 53, Issue 2 - Apr 2016
Volume 53, Issue 1 - Feb 2016
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Comparative Study of Full-Scale Propeller Cavitation Test and LCT Model Test for MR Tanker
Ahn, Jong-Woo ; Paik, Bu-Geun ; Seol, Han-Shin ; Park, Young-Ha ; Kim, Gun-Do ; Kim, Ki-Sup ; Jung, Bo-Jun ; Choi, Sung-Jun ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 171~179
DOI : 10.3744/SNAK.2016.53.3.171
In order to study correlation of the propeller cavitation performance between a full-scale ship and a model ship for the MR Tanker, the full-scale ship and the model tests were conducted. The full-scale ship test is composed of cavitation observation, pressure fluctuation and noise measurements, which are conducted using 2 observation windows and 8 pressure transducers installed inside the full-scale ship above the propeller. The model test in the Large Cavitation Tunnel(LCT) was conducted at the same conditions as that of the full-scale ship and its results are compared with those of the full-scale ship. Through the model-ship correlation analysis, it is considered that the experimental technique for the MR Tanker class ship was verified in LCT.
An Experimental Study on Wake Cavity Flow Characteristics of Two-dimensional Wedge Shaped Control Fins
Jeong, So-Won ; Ahn, Byoung-Kwon ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 180~187
DOI : 10.3744/SNAK.2016.53.3.180
As distinct from a slender body, the separation of the boundary layer on a bluff body give rise to complex wakes in which various kinds of vortices form, develop and interact with each other. In this paper, we investigate cavitation wake field behind wedge shaped two-dimensional fin models. Eight different models are tested at the Chungnam National University Cavitation Tunnel (CNU-CT). First, we measure wake cavity shapes and compare with numerical results, which shows the good agreement with each other. In addition, we demonstrate that wake flow characteristics of the control fin are clearly identified by the correlation analysis of high-speed camera images and pressure fluctuation measurements.
Development of Shear Flow Calculation Program for Ship Hull Transverse Section
Nho, In Sik ; Lee, Jeong-Youl ; Woo, Jeong-Jae ; Oh, Young-Taek ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 188~194
DOI : 10.3744/SNAK.2016.53.3.188
Accurate estimation of shear flows in thin-walled beam section is the key issue to evaluate shear stress distribution of ship hull transverse section under the shear forces acting on hull girder. It is regarded that the method using the warping functions obtained by finite element formulation is the state of the art of this field. Recently, however, IACS took effect the new version of CSR in which direct calculation process of shear flow was suggested. In the direct calculation process, shear flow of ship hull section can be obtained by the addition of determinate and indeterminate shear flows calculated respectively. So, in this paper, the shear flow evaluation codes based on the process proposed by IACS CSR and warping function based method were developed respectively. The calculated results of shear flows for the several examples of ship sections were compared with each other and considered in detail.
Comparative Study on Mechanical Behavior after Deformation Recovery of Polymeric Foam for Ships and Offshore Structures
Kim, Seul-Kee ; Kim, Jong-Hwan ; Lee, Jeong-Ho ; Park, Seong-Bo ; Lee, Jae-Myung ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 195~200
DOI : 10.3744/SNAK.2016.53.3.195
In this study, compression tests for the polyisocyanurate foam which is recognized as the insulation material for the storage tank of the liquefied natural gas (LNG) were carried out for investigation of the material characteristic of mechanical behavior. Deformation recovery ratio according to the various initial deformation levels were estimated and the mechanical behavior of foams that are experienced compressive deformation was also obtained experimentally. The test results were analyzed based on the conditions of initially applied strain level and engineering strain rate.
Studies on Planing Avoidance Control for a Ventilated Supercavitating Vehicle
Park, Jongyeol ; Kim, Seonhong ; Kim, Nakwan ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 201~209
DOI : 10.3744/SNAK.2016.53.3.201
Supercavitation is a technology that reduces frictional resistance of an underwater vehicle by surrounding it with bubbles. Supercavity is divided into natural supercavity and ventilated supercavity which is formed by artificially supplying gas. Planing forces are present when a section of the underwater vehicle goes outside of the cavitation region in the supercavity condition. Planing often leads to an unstable flight because it acts vertically on the body suddenly. In this paper, a relationship between the ventilation rate and the cavitation number is determined. Based on the relationship, desired cavitation number which can avoid to planing is determined and then ventilation controller is designed. The performance of the ventilation controller is verified with a depth change controller using the cavitator. Simulation results show that the ventilation controller can minimize the planing force and moment.
Direct Numerical Simulations of Turbulent Boundary Layer using OpenFOAM and Adapted Mesh
Lee, Sang Bong ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 210~216
DOI : 10.3744/SNAK.2016.53.3.210
Direct numerical simulations of a spatially developing turbulent boundary layer on a flat plate have been performed to verify the applicability of OpenFOAM and adapted mesh with prism layers to turbulent numerical simulation with high fidelity as well as provide a guideline on numerical schemes and parameters of OpenFOAM. Reynolds number based on a momentum thickness at inlet and a free-stream velocity was Re
A Numerical Study on the Effects of Maneuverability of Ship with Low Forward Speed by Increasing Rudder Force
Kim, Hyun-Jun ; Kim, Sang-Hyun ; Kim, Dong-Young ; Kim, In-Tae ; Han, Ji-Soo ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 217~227
DOI : 10.3744/SNAK.2016.53.3.217
Recent accidents of crude oil tankers have resulted in sinking, grounding of vessels and significant levels of marine pollution. Therefore, International Maritime Organization (IMO) has been strengthening the regulations of ship maneuvering performance in MSC 137. The evaluation of maneuvering performance can be made at the early design stage; it can be investigated numerically or experimentally. The main objective of this paper was to investigate the maneuvering performance of a VLCC due to the increase of rudder force at an early design stage for low speed in shallow water conditions. It was simulated in various operating condition such as deep sea, shallow water, design speed and low speed by using the numerical maneuvering simulation model, developed using MMG maneuvering motion equation and KVLCC 2 (SIMMAN 2008 workshop). The effect of increasing the rudder force can be evaluated by using numerical simulation of turning test and ZIG-ZAG test. The research showed that, increasing the rudder force of a VLCC was more effective on improving the turning ability than improving the course changing ability especially. The improvement of turning ability by the rudder force increasing is most effective when the ship is sailing in shallow water at low forward speed.
On the Design of Cantilever Type High Speed Towing Carriage with Excellent Acceleration Performance
Kim, Jae Sung ; Kim, Hyochul ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 228~236
DOI : 10.3744/SNAK.2016.53.3.228
Extraordinarily the establishment of towing tank has been initiated after the allocation of space at the basement floor of existing building through remodeling procedure. Therefore the asymmetric tank should be unavoidably determined by compromising with the allowable space and existing building structure. Consequently the shape of towing carriage ought to be selected as a cantilever type to match with the given environmental conditions. Finally the major role of the towing tank has been configured on the fundamental research work for the high speed marine vehicles. Due to the limited length of towing tank, it is appeared that the carriage should accelerated with 1.2m/sec
which is equivalent to twice of the maximum acceleration in ordinary practices on design application of carriage. In such a condition the exerted total power of motor could not be converted to traction force of the carriage without slip for the acceleration. To overcome these difficulties the contact pressure of a horizontal traction wheel to rail has been reinforced by the elastic recovery force of springs on supporting rollers. It is believed that the design experience of the high speed towing carriage under unusual circumferential condition and acceleration barrier could be utilized not only on the design of high speed towing carriage but also on the improvement of existing facilities.
A Novel Procedure for Mooring Chain Fatigue Prediction based on Maximum Principal Stress Considering Out-of-Plane and In-Plane Bending Effects
Choung, Joonmo ; Han, SeungOh ;
Journal of the Society of Naval Architects of Korea, volume 53, issue 3, 2016, Pages 237~248
DOI : 10.3744/SNAK.2016.53.3.237
As OPB and IPB moment-induced fatigue damage on mooring chain links were reported for a offloading buoy, verification of OPB and IPB fatigue has been a key engineering item in offshore structure mooring design. Mathematical and physical features of the conventional approach which was mainly explained in BV guideline are reviewed and disadvantages of the conventional approach are addressed in terms of stress proportionality and nonlinearity of OPB and IPB moments. In order to eradicate these disadvantages, a novel approach is newly proposed which is able to dispel apprehension on stress proportionality and is not dependent of nonlinearities of OPB and IPB moments. Significant differences between two approaches are suggested by comparing relations of OPB moment versus OPB interlink angle and IPB moment versus IPB interlink angle. For periodic OPB tension angle processes having three different OPB angle ranges with a simple irregular tension process, fatigue damage calculation reveals that OPB moment-induced fatigue damage has dominant portion to total fatigue damage. Comparative studies between two approaches also show that the conventional approach based on BV guideline predicts fatigue damage far conservatively since it assume unrealistic high stress concentration factor for tension load. Meanwhile IPB moment-induced fatigue damage is negligible compared to tension-induced fatigue damage.