• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.63-73
• /
• 1998

Due to the collapse of corrugated bulkheads subject to accidental flooding which is thought to be a primary cause of bulk carrier losses International Maritime Organization(IMO), the International Association of Classification Societies(IACS) and the leading classification societies are taking a growing concern for the structural safety of corrugated bulkheads of bulk carriers. To prevent progressive collapse of corrugated bulkhead in flooded condition particularly of forward cargo ho1d they try to make rules which require reinforcement of corrugated bulkhead structure. However, we are still confronted with the urgent problem of more accurate and efficient ultimate strength assessment for corrugated bulkheads. This paper develops a special purpose nonlinear FE program for analyzing progressive collapse behavior of corrugated bulkheads subject to lateral pressure loads. As verification examples, the program is applied to collapse strength analysis of steel corrugated bulkhead test model.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.2
• /
• pp.169-176
• /
• 2015

The mechanical properties of living tissues have been major subjects of interest in biomechanics. In particular, the characteristics of very soft materials such as the brain have not been fully understood because experiments are often severely limited by ethical guidelines. There are increasing demands for studies on remote medical operations using robots. We conducted compression tests on brain-like specimens made of gelatin to find substitutes with the mechanical properties of brain tissues. Using a finite element analysis, we compared our experimental data with existing data on the brain in order to establish material models for brain tissues. We found that our substitute models for brain tissues effectively simulated their mechanical behaviors.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.5
• /
• pp.371-378
• /
• 2018

Internal detonation of a warhead inside a compartment of naval vessel can result in serious blast damages including plastic deformation and rupture of the structural members especially bulkhead due to the huge explosive impact pressure, fragments and high temperature flame. To secure watertight integrity and to prevent the domino-type flooding of neighbouring compartments caused by the rupture of bulkheads, it is necessary to develop the structural design technology of Blast Hardened Bulkheads(BHB) which can resist the blast impact pressure of threatening weapons to increase the survivability of naval vessels. This study dealt with the simplified structural response analysis of BHB under impact pressure of confined explosion and aimed to develop the efficient and rational design method of BHB and joint structures which can be applied at initial design stage. The present 1st report dealt with the phenomena of explosive detonation surveying the preceding experimental/theoretical research and the characteristics of time history of blast pressure including the peak value and duration time were examined. And to predict the large plastic deformation behaviors of BHB by the huge blast pressure reasonably, the plastic hinge method including the membrane effects was formulated. It was applied to the simplified structural design equations. The following report will deal with the application and adjustment process of the structural scantling equations to the actual BHB design and verification of validity of them.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.20 no.2
• /
• pp.218-227
• /
• 2014

In this paper, it performed to the elastic-plastic large deflection series analysis using the experimental model and predicted a failure mode and ultimate strength. The collapse mode of numerical analysis model is formed a plastic hinge on loaded flange and consistent with the collapse mode of experimental model. Also, The yield line is formed in the web could observed that have occurred the crippling collapse mode and the ultimate loads of the experimental model and numerical analysis model have maintained linearly Means 1.07, Standard deviation 0.04, Coefficient of variation(COV) 0.04 and the result of ultimate loads have appeared approximately 8% error rate. it was found that very satisfied to the experimental results and the applied rules. if it is considered to be maintain a reasonable safety level, it is possible to predict the failure modes of aluminium alloy plate girders and ultimate loads.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.5
• /
• pp.27-36
• /
• 2016

This paper presents the investigation of the major influence factors on the degree of soil plugging for open-ended piles based on the Coupled Eulerian-Lagrangian (CEL) numerical technique. The main objective of this study was to investigate the effect of soil plugging on the response of piles in various conditions. Through comparison of the results of field load tests, the CEL methodology was found to be in good agreement with the general trend observed by in situ measurement. Additionally, the parametric studies were performed by controlling the soil conditions, soil elastic moduli, end-bearing conditions and multi layers. It was found that the degree of soil plugging for sand layers was greater than that of clay layers. Also, the degree of soil plugging increased with an increase in both the soil stiffness and length of pile embedded in the bearing layer.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.4
• /
• pp.211-217
• /
• 2007

Due to advanced new weapons and changes in the combat environment, survivability improvement methods for naval ship design have continuously evolved. Surface naval ships are easily detected by the enemy and, moreover, there are many attack weapons that may be used against surface naval ships. Therefore, it is important for modem naval ships, especially combat naval ships, to ensure survivability. In order to design a naval ship considering survivability, the designers are required to establish reasonable attack scenarios. An explosion may induce local damage as well as global collapse of the ship. Therefore, possible damage conditions should be realistically estimated at the design stage. In this study, an ALE technique was used to simulate the explosion analysis, and the survival capability of damaged naval ships was investigated. Especially, the author have establish the simple method of estimation of survival time for damaged naval ships.

• Journal of the Korean Institute of Gas
• /
• v.8 no.2 s.23
• /
• pp.54-60
• /
• 2004

In this paper, the maximum von Mises stress and maximum displacement of the corner protection and secondary bottom structures have been analyzed using a finite element analysis technique. The design criterion of the comer protection is 1,500Pa for a normal nitrogen gas purging process at the beginning stage of start-up procedure. This pressure is very safe for the structure safety of the comer protection and secondary bottom plates. The corner protection and secondary bottom plates fabricated by $9\%$ nickel steel sheet may plastically be distorted and fractured for the increased gas pressure of 8,475Pa, which produces the maximum von Mises stress of 833MPa and maximum displacement of 1.9m at the center of secondary bottom plate.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.8
• /
• pp.149-160
• /
• 2008

Offshore pile foundations are prone to lateral soil pressures resulting from embankment construction for the reclamation on deepwater soft clay. Since the 1990s, offshore reclamation has actively progressed in Korea, connecting with the development of Songdo newtown, Incheon newport, and Busan newport representatively. Special attention has been given to lateral soil-structure interaction problems related to passively-loaded offshore pile foundations. Based on a plane strain large deformation finite element (LDFE) approach, this paper presents the results of investigation into undrained (short-term) and drained (long-term) behavior of passively-loaded offshore pile foundations. This study examines the effects of major factors, such as soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. The results allowed quantification of differences in the magnitude of lateral soil pressure acting on the piles between undrained and drained phases.

• Journal of Korean Association for Spatial Structures
• /
• v.8 no.5
• /
• pp.47-58
• /
• 2008

Spatial structure is an appropriate shape that resists external force only with in-plane force by reducing the influence of bending moment, and it maximizes the effectiveness of structural system. With this character of the spatial structure, generally long span is used. As a result, large deflection is accompanied from the general frame. the structure is apt to result in a large deflection even though this structure experiences a small displacement in absence. Usually, nonlinear analysis in numerical analysis means geometric nonlinearity and material nonlinearity and complex nonlinearity analysis considers both of them. In this study, nonlinear equation of equilibrium considering geometric nonlinearity as per finite element method was applied and also considered the material nonlinearity using the relation of stress-strain in element. It is applied to find unstable result for tracing load-deflection curve in the numerical analysis tech. especially Arc-length method, and result of the analysis was studied by ABAQUS a general purpose of the finite element program. It is found that the present analysis predicts accurate nonlinear behavior of plane and space truss.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.2
• /
• pp.161-170
• /
• 2002

This paper describes a systematic way of simultaneously identifying the ambient pore pressure and the rigidity index $(=G/s_u)$ of soil by applying an optimization technique to the early part of piezocone dissipation test result. An analytical solution developed by Randolph & Wroth(1979) was implemented in normalized from to express the build-up and dissipation of excess pore pressures around a piezocone as a function of the rigidity index. An ambient pore pressure and optimal rigidity index were determined by minimizing the differences between theoretical and measured excess pore pressure curves using optimization technique. The effectiveness of the proposed back-analysis method was examined against the well-documented performance of piezocone dissipation tests(Tanaka & Sakagami, 1989), from the viewpoints of proper determination of selected target parameters and saving of test duration. It is shown that the proposed back-analysis method can evaluate properly the ambient pore pressure and the rigidity index by using only the early phase of the dissipation test data. Also, it is shown that the proposed back-analysis method permits the horizontal coefficient of consolidation to be identified rationally. Consideration for strain level of back-analyzed rigidity index shows that it corresponds to at least intermediate to large strain level.