Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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 51, Issue 6 - Dec 2014
Volume 51, Issue 5 - Oct 2014
Volume 51, Issue 4 - Aug 2014
Volume 51, Issue 3 - Jun 2014
Volume 51, Issue 2 - Apr 2014
Volume 51, Issue 1 - Feb 2014
Selecting the target year
A Study on the Resistance Test Method for Planning Hull Model using the High Speed Towing Carriage
Lee, Young-Gill ; Ha, Yoon-Jin ; Jeong, Kwang-Leol ; Chae, Soon-Jae ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 349~355
DOI : 10.3744/SNAK.2014.51.5.349
The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.
A Research on Completeness Assessment of Blocks using DOF Restriction
Kim, Chan Suk ; Shin, Jong Gye ; Noh, Jack You ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 356~361
DOI : 10.3744/SNAK.2014.51.5.356
Accurate block shape assessment is critical for ship manufacturing and a careful assessment of the shape of a fabricated block against the design shape is a core issue. However, in current fabrication practice, the shape of each block is evaluated manually using rigid body transformation. This manual evaluation process entirely depends on workers' experiences and knowledge and makes automation of block shape assessment difficult. In this paper we propose a computation method on the registration for shape assessment of a block during the fabrication process and for evaluation of its completion against the design shape. A conversion on matching method by adding DOF(degree of freedom) restriction is required to reach the goals. We test our method using a real block quality assessment data to demonstrate its applicability to real ship manufacturing process.
Development of the Container Securing Program for Large Container Carriers
Shin, Sang-Hoon ; Hwang, Gyu-Hyun ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 362~368
DOI : 10.3744/SNAK.2014.51.5.362
Container vessel sizes have constantly increased over the past two decades. With increasing ship sizes and higher container loading capacities, the adoption of lashing bridges has also increased. Today's lashing bridge designs range from 1st tier to 3rd tier lashing bridges. Container securing program of the past which is based on two lashing rods and 1st tier lashing bridge has to be improved to be suitable for the present time. The equilibrium equations in this study are established to cover the application of 3~4 lashing rods and 2nd~3rd tier lashing bridges. In addition developed program is improved to be able to calculate the reaction forces and optimum arrangement under the external lashing. An optimization algorithm which is suitable for the container securing problems involved the equality constraint has been also adopted in this study.
Effects of Hull Form Variations on Resistance and Seakeeping Performance of Planing Hulls with and without Incoming Regular Waves
Kim, Dong Jin ; Kim, Sun Young ; Kim, Seong Hwan ; Seo, Jeong Hwa ; Rhee, Shin Hyung ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 369~379
DOI : 10.3744/SNAK.2014.51.5.369
Planing hull forms have significant influences on those hydrodynamic performances in calm water and in waves. Therefore, the hydrodynamic performance of a planing vessel should be predicted by model tests or theoretical calculations, and be confirmed whether it shows the performance requirements at the design stage. In this study, four planing hull forms are designed with the goal of the improvement of resistance and seakeeping performance, and 1/6.5 scale model tests are carried out in Seoul National University towing tank. The effects of design parameters such as length-to-beam ratio, deadrise angle and forebody shape on the hydrodynamic performance are investigated, based on model test results. Running attitude and resistance of model ships in calm water are also estimated by empirical formulae proposed by Savitsky (1964; 2007; 2012), and compared with the model test results. It is shown that calm water performance of non-prismatic planing hulls can be predicted well by Savitsky (2012)'s formula which improves the original Savitsky(1964/2007)'s formula by taking into account the variations of deadrise angles, and the actual angles between the hull bottom and the free surface.
Dynamic Structural Response Characteristics of Stiffened Blast Wall under Explosion Loads
Kim, Sang Jin ; Sohn, Jung Min ; Lee, Jong Chan ; Li, Chun Bao ; Seong, Dong Jin ; Paik, Jeom Kee ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 380~387
DOI : 10.3744/SNAK.2014.51.5.380
Piper Alpha disaster drew attention to the damage likely to arise from explosions and fires on an offshore platform. And great concerns have been increased to prevent these hazards. Blast wall is one of the passive safety systems; it plays a key part of minimizing the consequences. However, a buckling due to explosion loads is a factor which can reduce the strength of blast wall. The buckling often occurs between web and flange at the center of blast wall. This study aims to find a solution for reinforcing its strength by installing a flat plate at the spot where the buckling occurs. First of all, ANSYS finite element method is adopted to numerically compute the structural resistance characteristic of blast wall by using a quasi-static approach. Sequentially, the impact response characteristics of blast wall are investigated the effect on thickness of flat plate by using ANSYS/LS-DYNA. Finally, pressure-impulse diagrams (P-I diagram) are presented to permit easy assessment of structural response characteristics of stiffened blast wall. In this study, effective use is made to increase structural intensity. of blast wall and acquired important insights have been documented.
Spatial Arrangement of Naval Ships Considering Functions and Relationships between Compartments
Hwang, InHyuck ; Shin, JungHack ; Kim, Youngmin ; Shin, JongGye ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 388~395
DOI : 10.3744/SNAK.2014.51.5.388
This paper presents a method that generates alternatives of spatial arrangement for naval ships with limited information. To attain this end, GA (General Arrangement) methodology and GA reports of existing naval ships are analyzed. In order to improve the current naval ship spatial arrangement method that relies on the experience and know-hows of designers, we propose a systematic spatial arrangement process using SLP (Systematic Layout Planning), which determines relative positions of the components by analyzing relationships among them. The proposed method, along with the GA process, is applied to a virtual naval ship and layout alternatives are generated to verify usefulness of the method.
Uncertainty Study of Added Resistance Experiment
Park, Dong-Min ; Lee, Jaehoon ; Kim, Yonghwan ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 396~408
DOI : 10.3744/SNAK.2014.51.5.396
In this study, uncertainty analysis based on ITTC(International Towing Tank Conference) Recommended Procedures is carried out in the towing-tank experiment for motion responses and added resistance. The experiment was conducted for KVLCC2 model in head sea condition. The heave, pitch and added resistance were measured in different wave conditions, and the measurement was repeated up to maximum 15 times in each wave condition in order to observe the uncertainty of measured data. The uncertainty analysis was carried out by adopting the ISO-GUM(International Organization for Standardization, Guide to the Expression of Uncertainty in Measurements) method recommended by ITTC. This paper describes the details about the analysis method, uncertainty and the measured uncertainty for each source. The uncertainty analysis results are summarized as a tabular form. To validate the accuracy of the present measurement, the experimental results are compared with the results of numerical computation and other experiment. From the present uncertainty analysis, the main sources of uncertainty are identified, which can be very useful to improve the accuracy for added resistance experiment.
Development of a Cartesian-based Code for Effective Simulation of Flow Around a Marine Structure - Integration of AMR, VOF, IBM, VIV, LES
Lee, Kyongjun ; Yang, Kyung-Soo ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 409~418
DOI : 10.3744/SNAK.2014.51.5.409
Simulation of flow past a complex marine structure requires a fine resolution in the vicinity of the structure, whereas a coarse resolution is enough far away from it. Therefore, a lot of grid cells may be wasted, when a simple Cartesian grid system is used for an Immersed Boundary Method (IBM). To alleviate this problems while maintaining the Cartesian frame work, we adopted an Adaptive Mesh Refinement (AMR) scheme where the grid system dynamically and locally refines as needed. In this study, We implemented a moving IBM and an AMR technique in our basic 3D incompressible Navier-Stokes solver. A Volume Of Fluid (VOF) method was used to effectively treat the free surface, and a recently developed Lagrangian Dynamic Subgrid-scale Model (LDSM) was incorporated in the code for accurate turbulence modeling. To capture vortex induced vibration accurately, the equation for the structure movement and the governing equations for fluid flow were solved at the same time implicitly. Also, We have developed an interface by using AutoLISP, which can properly distribute marker particles for IBM, compute the geometrical information of the object, and transfer it to the solver for the main simulation. To verify our numerical methodology, our results were compared with other authors' numerical and experimental results for the benchmark problems, revealing excellent agreement. Using the verified code, we investigated the following cases. (1) simulating flow around a floating sphere. (2) simulating flow past a marine structure.
Numerical Simulation of the Flow around Advancing Ships in Regular Waves using a Fixed Rectilinear Grid System
Jeong, Kwang-Leol ; Lee, Young-Gill ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 419~428
DOI : 10.3744/SNAK.2014.51.5.419
This paper presents a numerical simulation method for the flow around advancing ships in regular waves by using a rectilinear grid system. Because the grid lines do not consist with body surface in the rectilinear grid system, the body geometries are defined by the interaction points of those grid lines and the body surface. For the satisfaction of body boundary conditions, no-slip and divergence free conditions are imposed on the body surface and body boundary cells, respectively. Meanwhile, free surface is defined with the modified marker density method. The pressure on the free surface is determined to make the pressure gradient terms of the governing equations continuous, and the velocity around the free surface is calculated with the pressure on the free surface. To validate the present numerical method, a vortex induced vibration (VIV) phenomenon and flows around an advancing Wigley III ship model in various regular waves are simulated, and the results are compared with existing and corresponding research data. Also, to check the applicability to practical ship model, flows around KRISO Container Ship (KCS) model advancing in calm water are numerically simulated. On the simulations, the trim and the sinkage are set free to compare the running attitude with some other experimental data. Moreover, flows around the KCS model in regular waves are also simulated.
Study on the Estimation of the Optimum Trims in Container Carriers by using CFD Analysis of Ship Resistances
Park, Sang Hun ; Lee, Sang Bong ; Lee, Youn Mo ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 429~434
DOI : 10.3744/SNAK.2014.51.5.429
The main objective of the present study is to elucidate a correlation between ship resistances from computational fluid dynamics (CFD) and brake horse powers (BHP) from towing tank in container carriers. The tests were conducted for a range of combinations of trim conditions and speeds. To achieve this goal, 295 cases of numerical simulation have been performed using Star-CCM+ which had been statistically verified to predict ship resistances (Lee & Lee, 2014). Based on the normal distribution of resistance errors in all cases of the 4 container carriers, the confidence interval of numerical error was estimated as [-2.33%,+2.42%] with 95% confidence. The correlation coefficients between the ship resistances of CFD and the brake horse powers of the experiments were higher than 0.93. As a result, the numerical calculation of ship resistances is able to be utilized in order to provide a quick guidance in selection of the optimum loading condition.
A Numerical Analysis of Gravity and Free Surface Effects on a Two-Dimensional Supercavitating Flow
Kim, Hyoung-Tae ; Lee, Hyun-Bae ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 5, 2014, Pages 435~449
DOI : 10.3744/SNAK.2014.51.5.435
The effects of the gravity field and the free surface on the cavity shape and the drag are investigated through a numerical analysis for the steady supercavitating flow past a simple two-dimensional body underneath the free surface. The continuity and the RANS equations are numerically solved for an incompressible fluid using a
turbulence model and a mixture fluid model has been applied for calculating the multiphase flow of air, water and vapor using the method of volume of fluid and the Schnerr-Sauer cavitation model. Numerical solutions have been obtained for the supercavitating flow about a two-dimensional
wedge in wide range of depths of submergence and inflow velocities. The results are presented for the cavity shape, especially the length and the width, and the drag of the wedge in comparison with those of the case for the infinite fluid flow neglecting the gravity and the free surface. The influences of the gravity field and the free surface on the aforementioned quantities are discussed. The length and the width of the supercavity are reduced and the centerline of the cavity rises toward the free surface due to the effects of the gravity field and the free surface. The drag coefficient of the wedge, however, is about the same except for shallow depths of submergence. As the supercavitating wedge is approaching very close to the free surface, it is found the length and the width of a cavity are shorten even though the cavitation number is reduced. Also the present result suggests that, under the influence of the gravity field and the free surface, the length of the supercavity for a certain cavitation number varies and moreover is proportional to the inverse of the submergence depth Froude number.