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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 52, Issue 6 - Dec 2015
Volume 52, Issue 5 - Oct 2015
Volume 52, Issue 4 - Aug 2015
Volume 52, Issue 3 - Jun 2015
Volume 52, Issue 2 - Apr 2015
Volume 52, Issue 1 - Feb 2015
Selecting the target year
Development of the New Energy Saving Device for the Reduction of Fuel of 176k Bulk Carrier
Song, Hyun-Jin ; Kim, Moon-Chan ; Lee, Won-Joon ; Lee, Kyoung-Wan ; Kim, Ji-Hee ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 419~427
DOI : 10.3744/SNAK.2015.52.6.419
Recently Energy Saving Device has been developed actively due to the regulation of the EEDI. This Energy Saving Device which is newly developed is integrated duct and stator. This paper verified performance of the Energy Saving Device through CFD. The experimentation to find the best pitch angle of each blade of the stator designed has been conducted. The angle of incidence of the duct has been obtained through the measurement of the wake. The experimentation has been carried out with and without Energy Saving Device. The efficiency increase was through these two experiments.
Performance Trial-Test of the Full-Scale Driving Pump for the Large Cavitation Tunnel(LCT)
Ahn, Jong-Woo ; Kim, Gun-Do ; Kim, Ki-Sup ; Park, Young-Ha ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 428~434
DOI : 10.3744/SNAK.2015.52.6.428
The objective of the present study is to analyze the results of the trial-test for the full-scale driving pump, which is arranged in the LCT (Large Cavitation Tunnel). Firstly, the reasons of selecting the final design pump are introduced in terms of the performance analysis in model tests. The trial-test items for the full-scale driving pump are measurements of output current/voltage at the inverter of the main motor and the flow velocity in the LCT test section. The test results show the increase in flow rate of about 10.7% and the decrease in pump head of about 26%, compared with those of final design-pump specification. The motor power has the margin of about 22%. The performance analysis for the full-scale pump is conducted using the commercial code (CFX-10). The delivered power calculated with CFX-10 shows good agreement with that extracted from the full-scale pump test. It is found that CFX-10 is useful to analyze a full-scale pump.
Flaw Assessment on an Offshore Structure using Engineering Criticality Analysis
Kang, Beom-Jun ; Kim, Yooil ; Ryu, Cheol-Ho ; Ki, Hyeok-Geun ; Park, Sung-Gun ; Oh, Yeong-Tae ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 435~443
DOI : 10.3744/SNAK.2015.52.6.435
Offshore structure may be considerably vulnerable to fatigue failure while initial flaw propagates under cyclic loading, so crack propagation analysis/fracture/yield assessments about initial flaw detected by NDT are necessarily required. In this paper, case studies have been conducted by flaw assessment program using engineering criticality analysis (ECA) approach. Variables such as flaw geometry, flaw size, structure geometry, dynamic stress, static stress, toughness, crack growth rate, stress concentration factor (SCF) affected by weld are considered as analysis conditions. As a result, the safety of structure was examined during fatigue loading life. Also, critical initial flaw size was calculated by sensitivity module in the developed program. The flaw assessments analysis using ECA approach can be very useful in offshore industries owing to the increasing demand on the engineering criticality analysis of potential initial flaws.
Ultimate Strength Assessment and Design of T type Lifting Lug
Lee, Joo-Sung ; Kim, Min-Sul ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 444~451
DOI : 10.3744/SNAK.2015.52.6.444
Lifting lugs are frequently used in shipyard to transport and turn over blocks of ship and offshore structures. As the shipbuilding technology develops, blocks has become bigger and bigger, and block management technology takes a more important role in shipbuilding to enhance the productivity. For the sake of economic as well as safe design of lug structure, more rational design procedure based on the rigorous structural analysis is needed. This study is concerned with the optimum design of T type lug which is frequently used in shipyard. The optimum thickness of lug's main body is to be determined based on the results of non-linear strength analysis. As far as the present results for the present T type lugs having different capacity are concerned, it seems to be necessary to review the current design procedure of lug structure. The present design procedure can be extensively used in design of various types of lug structures used in shipyard.
Development of Bench Tester for Designing the Passive Anti-Rolling Tanks
Lew, Jae-Moon ; Kim, Hyochul ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 452~459
DOI : 10.3744/SNAK.2015.52.6.452
It is important to use bench test results in the design process of anti-rolling tanks. Traditional bench tester is usually designed to perform only roll motions about a fixed axis and relatively small so that the viscous effects may not be neglected. Novel bench tester which could adjust the motion center to realize the coupled motion of sway and roll has been devised and manufactured therefore, large scaled bench tester could be utilized for designing the passive anti-rolling tanks. The time history of the reference signal from the rotation sensor of the bench tester have been recorded and processed to determine the phase angle to derive the Response Amplitude Operator(RAO) of the stabilized ship. The breadth of ART tank model should be large up to 2 m to diminish viscous scale effect and the vertical position of the tank can be varied with the ship's center of motion. The periods and the amplitude of roll motion can be varied from 1.5 sec to 5 sec and up to ±20°, respectively. The components of the tester was expressed in three dimensional digital mockup (DMU) and assembled together in the CAD space. The final configuration of the bench tester has been determined by confirming the smooth operation of the moving parts without interference through the animation in CAD space. New analytic logic are introduced for the determination of hydrodynamic moment and phase difference due to fluid motion in ART and verified through the test. The developed bench tester is believed to be effective and accurate for the verification of stabilization effect of ART taking into the consideration of the sway effect in the design stage.
Experimental Study of the Free Roll Decay Test for the Evaluation of Roll Damping Coefficients
Kim, Namwoo ; Kim, Yong Jig ; Ha, Youngrok ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 460~470
DOI : 10.3744/SNAK.2015.52.6.460
In general ships and FPSOs, roll damping is very small and consequently roll motion is very large at the roll resonance frequency. Proper evaluation of the roll damping coefficient at the resonance frequency is an important task in the study of roll motion and usually it is done by the analysis of free roll decay tests. The relative decrement method based on energy relation has been used mainly for the evaluation of roll damping coefficient from the roll decay test so far. As another method, the logarithmic decrement method based on equivalent linear decay assumption can be used for the same purpose and it is relatively simple. In this paper, both of the relative decrement method and the logarithmic decrement method are used for the evaluation of roll damping coefficient including quadratic damping from the free roll decay tests, and their results are cross-checked for verifying the obtained damping coefficients. Through applications to a box-type floating body equiped with bilge keels, it is shown that the two methods give almost the same damping coefficients in a practical view point and the cross-check of their results is to be a good tool to prevent a possible error. And also the quantitative effects of the bilge keels on the roll damping of box-type floating body are shown and discussed.
Computational and Experimental Studies on Added Resistance of AFRAMAX-Class Tankers in Head Seas
Oh, Seunghoon ; Yang, Jinho ; Park, Sang-Hun ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 471~477
DOI : 10.3744/SNAK.2015.52.6.471
When a ship sails in a seaway, the resistance on a ship increases due to incident waves and winds. The magnitude of added resistance amounts to about 15–30% of a calm-water resistance. An accurate prediction of added resistance in waves, therefore, is essential to evaluate the performance of a ship in a real sea state and to design an optimum hull form from the viewpoint of the International Maritime Organization (IMO) regulations such as Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI). The present study considers added resistance problem of AFRAMAX-class tankers with the conventional bow and Ax-bow shapes. Added resistance due to waves is successfully calculated using 1) a three-dimensional time-domain seakeeping computations based on a Rankine panel method (three-dimensional panel) and 2) a commercial CFD program (STAR-CCM+). In the hydrodynamic computations of a three-dimensional panel method, geometric nonlinearity is accounted for in Froude-Krylov and restoring forces using simple wave corrections over exact wet hull surface of the tankers. Furthermore, a CFD program is applied by performing fully nonlinear computation without using an analytical formula for added resistance or empirical values for the viscous effect. Numerical computations are validated through four degree-of-freedom model-scale seakeeping experiments in regular head waves at the deep towing tank of Hyundai Heavy Industries.
An Analysis of Characteristic of Ice Load Distribution on Model Ship due to Ship and Ice Interaction
Jeong, Seong-Yeob ; Choi, Kyungsik ; Cheon, Eun-Jee ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 478~484
DOI : 10.3744/SNAK.2015.52.6.478
Knowledge about ice load distribution along the ship hull due to ship-ice interaction can provide important background information for the development of design codes for ice-going vessels. The objective of this study is to understand ship and ice interaction phenomena and determine the magnitude of ice load acting along a ship hull. The model tests were performed in the ice model basin in Korea Research Institute of Ships and Ocean engineering (KRISO) with the model of icebreaking ship Araon. Self-propulsion tests in level ice were performed with three difference model ship speeds. In the model tests, three tactile sensors were installed to measure the spatial distribution of ice load acting at different locations on a model ship, such as the bow and shoulder areas. Variation in the distribution of ice load acting on a model hull with ship speed is discussed.
A Model Test Study on the Effect of the Stern Interceptor for the Reduction of the Resistance and Trim Angle for Wave-piercing Hulls
Kim, Dae Hyuk ; Seo, Inn-Duk ; Rhee, Key-Pyo ; Kim, Nakwan ; Ahn, Jin-Hyung ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 485~493
DOI : 10.3744/SNAK.2015.52.6.485
Planing hull form is widely used as a high speed vessel hull. There is a problem of the planing hull not solved yet. The problem is that the planing hull has very large vertical acceleration and large heave and pitch motions. As one method for overcoming this problem, there is "wave-piercing hull". Before the motion in waves is investigated, the resistance and running attitude must be investigated. In this paper, the running attitude and resistance of two wave-piercing hulls are investigated by model tests. Model test results show that the wave-piercing hulls have large trim angle and sinkage at the high speed, so additional model tests are conducted by using the hull appended by stern interceptor that is very thin plate to increase the hydrodynamic pressure at the attached location. The results are compared with other planing hulls and the resistance components and the hydrodynamic force are discussed. From the model test results, it can be known that the stern interceptor is the effective appendage for the reduction of the resistance and trim angle of wave-piercing hull.
A Study on the Manoeuvrability of KVLCC2 in Shallow Water by Free Running Model Test
Yun, Kunhang ; Yeo, Dong Jin ; Park, Byoungjae ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 494~500
DOI : 10.3744/SNAK.2015.52.6.494
It has been reported that a ship sailing in shallow water possesses better straight-line stability due to the change of fluid flow around the ship. This tendency affects manoeuvring characteristics of the ship. To investigate this phenomenon, indoor free running model test(FRMT) on KVLCC2 was carried out in three water depth conditions(H/T = 1.2, 1.5 & 2.0). Turning circle tests(± 35° ) and zigzag tests(± 20° /5° and ± 20° /10° ) were conducted with newly developed indoor FRMT system, and the manoeuvring results were compared with test results from other institutes. As the water depth decreased, the yaw rate of the ship decreased, and the distances of circular trajectories at the same heading angle increased in the turning circle tests. The first overshoot angles of the zigzag tests decreased. From both tests, the time for course change increased as the water depth decreased. These manoeuvring characteristics show that KVLCC2 in shallow water becomes more stable in terms of straight-line stability.
Comparison of Methods for Matching Corresponding Points of an Inter-Surface for Hull Plate Forming
Kim, Chan Suk ; Shin, Jong Gye ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 501~508
DOI : 10.3744/SNAK.2015.52.6.501
Lately, much research on hull plate forming has been successful in improving productivity of the forming process. Those researches include forming methods, forming information, and automation. After forming each plate, the fabricated surface is compared with the corresponding designed surface. Two sets of data from the designed and fabricated surfaces are matched in order to complete the forming process. However, only a few papers deals with comparison of two surfaces. This paper presents a new matching method based on the bounding volume hierarchy (BVH). By comparing the conventional method, this new approach using BVH shows not only good agreement but also better advantages.
Study on the Mooring Stability of Floating Dock with Ultra Large Offshore Structure
Yang, Seungho ; Cho, Jinwoog ; Kim, Hyunjoe ; Kim, Booki ;
Journal of the Society of Naval Architects of Korea, volume 52, issue 6, 2015, Pages 509~519
DOI : 10.3744/SNAK.2015.52.6.509
Mooring stability of floating dock for construction of Ichthys CPF (central processing facilities), an ultra large offshore structure, was studied. Normal and typhoon conditions were considered for mooring analysis. There have been changes in construction stages of the CPF as project progresses. These changes were reflected on the mooring stability analysis for both conditions. In order to secure the mooring stability of the floating dock for Ichthys CPF under typhoon, maximum loads of mooring chains and maximum offset of the floating dock with Ichthys CPF were examined. Also the shapes of the catenary mooring were investigated to check interferences among mooring chains. As it was confirmed that the mooring loads were within SWL (safe working load) of mooring chains and underwater sinkers, the mooring stability of the floating dock for construction of Ichthys CPF was secured. By achieving security of mooring stability of the floating dock, it is assured that Ichthys project is on its way to success.