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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 44, Issue 6 - Dec 2007
Volume 44, Issue 5 - Oct 2007
Volume 44, Issue 4 - Aug 2007
Volume 44, Issue 3 - Jun 2007
Volume 44, Issue 2 - Apr 2007
Volume 44, Issue 1 - Feb 2007
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Numerical Analysis of Flow Characteristics of a Twin-skeg Container Ship with Variation of Stern Hull Shape
Kim, Hee-Taek ; Van, Suak-Ho ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 551~563
DOI : 10.3744/SNAK.2007.44.6.551
Numerical analysis for flow characteristics of a twin skeg container ship was carried out according to skeg vertical angles(
) and skeg distances(16m, 20m, 24m) by using a commercial CFD code, FLUENT. Computed: pressure distributions, wake distributions and resistance coefficients have been compared with experimental and WAVIS results carried out by MOERI. Flow characteristics from numerical analysis such as nominal wake fractions, wake distribution and directions of the transverse vectors give good agreement with WAVIS results, even though there are quantitative discrepancy comparing with experimental measurements at the propeller plane. It is found that the better resistance performance can be obtained with the increase of the skeg vertical angle and the decrease of the skeg distance, which are mainly caused by viscous pressure resistance due to the skeg form and pressure recovery around the skeg. In addition, a vertical angle of the skeg gives more effect to the resistance coefficient comparing with the skeg distance. On the basis of results of the present study, it shows that numerical analysis using the commercial code, FLUENT, is useful and efficient tool for the evaluation of the complex stern hull form with twin-skegs.
Development of CFD Based Stern Form Optimization Method
Kim, Hee-Jung ; Chun, Ho-Hwan ; Choi, Hee-Jong ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 564~571
DOI : 10.3744/SNAK.2007.44.6.564
In the present study, stern form optimization has been carried out using computational fluid dynamics (CFD) techniques. The viscous pressure drag has been minimized to optimize stern shape. Parametric modification function has been used to modify the shape of the hull. By the use of the parametric modification function and algebraic scheme to grid manipulation, the initial ship geometry was easily deformed according to change of design parameters. For purpose of illustration, KRISO 319K VLCC (KVLCC) is chosen for example ship to demonstrate stern form optimization. The numerical results indicate that the optimized hull yields a reduction in viscous resistance.
A Simplified Horizontal Maneuvering Model of a RIB-Type Target Ship
Yoon, Hyeon-Kyu ; Yeo, Dong-Jin ; Fang, Tae-Hyun ; Yoon, Kun-Hang ; Lee, Chang-Min ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 572~578
DOI : 10.3744/SNAK.2007.44.6.572
A Rigid Inflatable Boat (RIB) is now widely used for commercial and military purpose. In this paper, it is supposed that seven-meter-class RIB be used as an unmanned target ship for naval training. In order to develop many tactical maneuvering patterns of a target ship, a simple horizontal maneuvering model of a RIB is needed. Therefore, models of speed and yaw rate are constructed as the first-order differential equations based on Lewandowski#s empirical formula for steady turning circle diameter of a conventional planning hull. Some parameters in the models are determined using the results of sea trial tests. Finally, proposed models are validated through the comparison of the simulation result with the sea trial result for a specific scenario. Even though a simple model does not represent the horizontal motion of a RIB precisely, however, it can be used enough to develop tactical trajectory patterns.
Development of Algorithm for Stereoscopic PIV using Normalized Cross-correlation
Oh, Jung-Keun ; Kim, Yoo-Chul ; Ryu, Min-Cheol ; Koh, Won-Kyou ; Suh, Jung-Chun ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 579~589
DOI : 10.3744/SNAK.2007.44.6.579
Contrary to the conventional single-point measuring devices such as LDV, pitot-tube, hot-wire, etc., it would be possible to measure instantaneously 3-D flow fields with a stereoscopic PIV system. In this paper, we present an analysis algorithm for a stereoscopic PIV system using the normalized cross-correlation (NCC) and a 3-D calibration based reconstruction method. The evaluation method based on NCC is one of the most accurate correlation-based methods. We validated the developed algorithm through a benchmarking comparison with 3-D artificial SPIV images and calibration target images.
A Study on the Reduction of Fillet Welding Deformation by Applying the Tensioning Method
Lee, Joo-Sung ; Park, Jae-Woo ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 590~597
DOI : 10.3744/SNAK.2007.44.6.590
The portion of thin plate is expected to increases as to the development of design and fabrication technology. The weld-induced deformation is more serious in thin plates than in thick plates because heat affect zone of thin plates is wider than that of thick plates, and in addition internal and external constraints much more influence upon weld-induced deformation of thin plates. This paper is aimed at applying the mechanical tensioning method to fillet weld of thin plates to reduce the weld-induced deformation. For this purpose, fillet welding tests have been carried out for several thin plate specimens with varying plate thickness and magnitude of tensile load. From the present study, it has been found that the tensioning method is effective on reduction of weld-induced deformation.
A Study on the Prediction of Welding Distortion and Residual Stress for Channel I Butt SA Weldment Using FE Analysis
Shin, Dae-Hee ; Shin, Sang-Beom ; Lee, Joo-Sung ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 598~604
DOI : 10.3744/SNAK.2007.44.6.598
The purpose of this study is to establish the predictive method of welding distortion and residual stress for the channel I butt SA (submerged arc) weldment using FEA. In order to do it, the heat input model for the weldment was defined as the combined heat source with the surface heat flux of gaussian distribution and volumetric heat source uniformly distributed within weld groove by comparing the shapes of molten pool and temperature distribution obtained by FEA with those of experiments. The arc efficiency of SA welding for two-dimensional FE analysis was evaluated as 0.85. The welding distortion and residual stress of the weldment obtained by FEA and heat input model proposed have a good agreement with those obtained by experiment. Based on the results, it was suggested that the proper heat input model should be required to evaluate the welding distortion for weldment.
Development of Strength Evaluation System Using the Combined Grillage and Shell Element for the Strength around the Opening
Kim, Sung-Chan ; Lee, Kyung-Seok ; Song, Jae-Young ; Kim, Kyung-Su ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 605~611
DOI : 10.3744/SNAK.2007.44.6.605
A ship is composed of many grillage structures especially the deck which is consists of primary girders, transverse and longitudinal members. Several holes are arranged on these primary members for pipes, vents, etc. which cause stress concentration due to the discontinuity of the member. It is not easy to get the stress values around all these holes because of the huge amount of time necessary for computations. In this paper, a simple method to compute for the stress around the holes is suggested. This method is composed of two steps which are grillage analysis for primary members and detailed stress analysis using the results of the grillage analysis. This method is made for the design of the primary members with openings supporting the deck structure.
Detail-design Guidance for the Openings on the Web Structure Supporting the Deck
Kim, Sung-Chan ; Lee, Kyung-Seok ; Song, Jae-Young ; Kim, Kyung-Su ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 612~618
DOI : 10.3744/SNAK.2007.44.6.612
There are a lot of openings, holes and slots in ship structural members. It is not easy to solve the troubles around the openings adequately at the detail design stage, because there are a lot of concerning locations. There are not also clear design rules of classification societies and it is not possible to apply direct calculation for all the concerning members. Therefore, it is necessary to set up simplified approach such as a standard or guidance in order to decide the opening design quickly. For this study, guidance and regulations of each classification and several companies were surveyed. Grillage analysis and the refined mesh method were used to evaluate the strength around hole considering boundary condition and more detailed member arrangement. As a result, the standard for opening design was established and verified.
Experimental Study on the Fluid-structure Interaction of Flexible Plate
Liu, Zhen ; Nho, In-Sik ; Hyun, Beom-Soo ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 619~626
DOI : 10.3744/SNAK.2007.44.6.619
This paper presents an experimental study on deformations and force characteristics of flexible plates both in air and water. The focus is on the complicated interaction problem between the fluid and flexible structures. The displacements and forces of free oscillating plates are measured and compared with each others. The effects of several plate coefficients are investigated i.e. plate thickness, aspect ratio, plate area, plate width ratio, bending angle. For the verification of the experimental results, some of them are compared with numerical simulation and show reasonable agreements.
Theoretical Analysis of Interface Crack on Thin Plate
Nho, Hwan-Jin ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 627~634
DOI : 10.3744/SNAK.2007.44.6.627
A bonded plate or a coated part can be debonded by external impact or thermal expansion. To analyse adhesive strength, the blister test is generally adopted. In this paper, a blister test is modelled theoretically and then the stability and bifurcation of the blister are studied under several different cases. The blister is simplified to consist of a pure bending plate attached elastically to the rigid substrate. Expression of the energy release rate is obtained as a form of an explicit function for a circular-type blister or tunnel-type blister grown by controlling the internal pressure or internal volume. Stability and bifurcation are also studied in the frame of the quasi-static evolution. The study shows that the circular- type blister propagates with the first mode of bifurcation and that the tunnel-type blister propagates with a regular wave. It is proved that the waves have the same form on two side lines of the tunnel and that the wave length can be obtained. When the internal pressure is controlled, the blister is unstable, but when the internal volume is controlled, it is stable.
A Development of EPISODE Solar Boat
Choi, Jung-Kyu ; Kim, Hee-Taek ; Lee, Sung-Soo ; Lee, Kwang-Beom ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 635~646
DOI : 10.3744/SNAK.2007.44.6.635
Human Powered Vessel Festival (HPVF) hosted by the College of Engineering of Chungnam National University, the Society of Naval Architects of Korea and the Korea Ocean Research & Development Institute has been held annually in Daejon since 1999. Solar boat powered by solar energy appeared for the first time in 2006, and it is expected that more new teams will enter this competition in the coming years. In this paper it is described that design procedures and manufacture processes of the solar boat named EPISODE. Firstly, It is aimed to understand compositions of the electric system and their performance properties and to show the design procedures using commercial design packages line WAVIS, CATIA, HCAD etc. Through the trial test, we confirmed ship speed, maneuverability, durability and operation condition of the electric system and found some problems. We plans to make reported problems go away and install hydrofoils for more improved speed performance.
A Study on Discrete Event Simulation of Shipyard Outdoor Block Movement
Lee, Choon-Jae ; Lee, Jang-Hyun ; Woo, Jong-Hun ; Shin, Jong-Gye ; Ryu, Cheol-Ho ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 647~656
DOI : 10.3744/SNAK.2007.44.6.647
Simulation model of outdoor block movement of shipyard is implemented in this paper. The load of the outdoor workshops in a shipyard influences a mid-term planning and scheduling of the shipyard. Since the load analysis is expected in advance before confirming the planning and scheduling, a discrete event simulation (DES) may be a good solution. The accuracy of DES is up to the accurate modeling of Products, Processes, and Resources (PPR) included in a system. PPR in the outdoor system are clearly defined and the simulation model for the outdoor logistics is implemented by modeling the selective PPR with the help of a DES tool which is programmable by users. The simulation model is verified by comparing the results with the real shipyard data. The outputs through the simulation are discussed.
Study on Application Fields and Basic Characteristics of Ubiquitous Computing Technologies in a Ship
Cho, Seong-Rak ; Paik, Bu-Geun ; Park, Beom-Jin ; Lee, Dong-Kon ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 657~665
DOI : 10.3744/SNAK.2007.44.6.657
The object of this paper is to describe the ubiquitous computing technologies for ship, which is produced and assembled by many steel blocks. It includes the testing of a 2.4GHz wireless communications platforms and radio-frequency identification technology with the blocks disturbing the wireless communication. The power line communication that is established in a ship already is also experimented for some data transfer. Also, possible application areas of the ubiquitous computing technology to ships are discussed. At last, the test bed copied from an actual vessel was installed and data acquisition tests were established using wire and wireless communication. In this paper, we implemented some ubiquitous computing technologies in the test bed simulating a ship environment and investigated the basic characteristics of ubiquitous computing technologies.
Pressure Analysis of Sterntube after Bush Bearing Considering Elastic Deflection of Misaligned Journal and Partial Slope of Bearing Bush
Choung, Joon-Mo ; Choe, Ick-Heung ;
Journal of the Society of Naval Architects of Korea, volume 44, issue 6, 2007, Pages 666~674
DOI : 10.3744/SNAK.2007.44.6.666
It is very important to estimate static squeezing pressure distributions for lining material of sterntube after bearing at dry dock stage since the maximum squeezing pressure value can be one of the significant characteristics representing coming navigation performances of the propulsion system. Moderate oil film pressure between lining material and propulsion shaft is also essential for safe ship service. In this paper, Hertz contact theory is explained to derive static squeezing pressure. Reynolds equation simplified from Navier-Stokes equation is centrally differentiated to numerically obtain dynamic oil film pressures. New shaft alignment technology of nonlinear elastic multi-support bearing elements is also used in order to obtain external forces acting on lining material of bearing. For 300K DWT class VLCC with synthetic bush of sterntube after bearing, static squeezing pressures are calculated using derived external forces and Hertz contact theory. Optimum partial slope of the after bush is presented by parametric shaft alignment analyses. Dynamic oil film pressures are comparatively evaluated for partially bored and unbored after bush. Finally it is proved that the partial slope can drastically reduce oil film pressure during engine running.