• Journal of Welding and Joining
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• v.28 no.4
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• pp.41-48
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• 2010

The purpose of this study is to establish the control method of the global bending distortion caused by fabrication process of hatch-cover in a container ship. In order to do it, the transitional behavior of global bending distortion in the deck of hatch-cover during fabrication process was measured by 3-dimensional measuring instrument. From the results, the principal factor controlling the global bending distortion was identified as the bending moment associated with the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the change of the centroid axis of hatch-cover in each fabrication process. Therefore, in this study, with the predictive equations of the longitudinal shrinkage force and transverse shrinkage caused by welding and flame heating and the simplified thermo elastic method, the predictive method for the global bending distortion was established and verified by comparing with the measured result. Based on the results, the amount of reverse bending distortion of main stiffeners was determined to prevent the global bending distortion of hatch-cover.

• Journal of Ship and Ocean Technology
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• v.3 no.1
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• pp.27-41
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• 1999

The objective of the paper is to study the impact of changing the traditional hull design of bulk carriers by providing them with a double hull while keeping the same deadweight. It is demonstrated that by introducing the double hull the structural reliability is increased throughout the entire life and also the extend of the needed repair is reduced. The results are obtained with recently developed mathematical tools for the reliability assessment of ship hulls subjected to the existence of multiple cracks both in the stiffeners and in the plating and it models the crack growth process. The effect of corrosion is represented as time dependent. The long-term stress range acting on the elements is defined as a function of the local transverse pressure of the internal cargo and outside sea water combined with the stresses resulting from the longitudinal bending of the hull, which is a combined with the stresses resulting from the longitudinal bending of the hull, which is a combineation of horizontal and vertical bending moments. The effect of maintenance actions is modelled as a stochastic process. The results show that a different design of the midship section improves the structural safety and also the economy with respect to structural repair of bulk carriers.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.365-375
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• 2006

The HR Plates made hot rolled coils is lower than general structural steel plates in price. No difference between general steel plates and HR Plates with thickness up to 22mm are found in most characters such as cutting operation, fabrication and even welding. It can be concluded that HR Plates with thickness up to 22mm can be applied to flanges and webs of any girders as well as longitudinal ribs, longitudinal and vertical stiffeners of steel bridges appropriately. To increase the demand of HR Plates with thickness up to 22mm, it is necessary that HR Plates is applicable to full member in steel bridge including main girder.In this study, availabilities of the narrow steel box girder of light railway transit with HR Plate width as a main member are discussed. For application of HR Plate to steel bridge with 50m span or more, new support systems in three types are presented. Computational analysis is performed in 15 bridge models of light railway transit with beam element and plate element. As a analysis results, three models in light railway transit are presented. We finally come to the conclusion that HR Plates can be apply to narrow steel box girder in the light railway transit.

• Journal of Korean Society of Steel Construction
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• v.23 no.4
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• pp.455-464
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• 2011

In this study, the buckling analysis of the vertically curved stiffened web plate was conducted through finite-element analysis, using an eight- and nine-node flat shell element with a substitute shear strain field. To investigate the buckling behavior of the vertically curved web plate with a longitudinal or vertical stiffener under in-plane moment loading, parametric studies were conducted for the variation of the width (b) and ratio of the bending stiffness of the stiffener to that of the plate (${\gamma}=EI/bD$). The static behavior of the vertically curved web plate without a stiffener was also investigated, and then the buckling abilities of the longitudinal and vertical stiffeners were compared under moment loading.

• Steel and Composite Structures
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• v.29 no.3
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• pp.309-318
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• 2018

Steel girders are the structural members often used for passing long spans. Mostly being subjected to patch loading, or concentrated loading, steel girders are likely to face sudden deformation or damage e.g., web breathing. Horizontal or vertical stiffeners are employed to overcome this phenomenon. This study aims at assessing the feasibility of a machine learning method, namely the support vector machines (SVM) in predicting the patch loading resistance of longitudinally stiffened webs. A database consisting of 162 test data is utilized to develop SVM models and the model with best performance is selected for further inspection. Existing formulations proposed by other researchers are also investigated for comparison. BS5400 and other existing models (model I, model II and model III) appear to yield underestimated predictions with a large scatter; i.e., mean experimental-to-predicted ratios of 1.517, 1.092, 1.155 and 1.256, respectively; whereas the selected SVM model has high prediction accuracy with significantly less scatter. Robust nature and accurate predictions of SVM confirms its feasibility of potential use in solving complex engineering problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.3
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• pp.159-163
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• 2003

This study is object to minimum weight design of stiffened laminated composite flat panel. Various buckling load factors are obtained for stiffened laminated composite flat panels with rectangular type longitudinal stiffeners and various aspect ratios, which are made from Carbon/Epoxy USN150 prepreg and are simply-supported on four edges under uniaxial compression.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1073-1081
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• 2013

The definition of the radiation efficiency is very important to estimated underwater radiated noise of a ship. Considering the structure of the ship, it can be found that the hull of a ship consists of a lot of plates supporting by longitudinal and transverse stiffener. Therefore, various modes of the hull vibration occur related to the combination of these plates including stiffeners. In this paper, the method to define the radiation efficiency is suggested considering the vibration mode of the hull based on Uchida's experimental equation of the radiation efficiency. The suggested method is verified by the experiments with various kinds of naval vessels.

• Journal of Welding and Joining
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• v.28 no.5
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• pp.64-68
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• 2010

The purpose of this study is to develop the control technology of global distortion in the deck of superstructures during manufacturing processes. The behavior of global distortion in the deck was evaluated by FEA and verified through comparing with the measured results by 3D measuring instrument. It was seen from the results that the principal factor inducing the global distortion is to be the bending moment associated with the longitudinal shrinkage force and transverse shrinkage caused by welding of stiffeners and flame heating to correct the excessive local out-of-plane distortion. Based on the results, the amount of reverse distortion in the thin deck plate was determined to control the global distortion in the deck plate. The proposed distortion control technology was verified by applying it to the actual structure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.254-261
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• 1997

In desingin plate bridges, the width-thickness ratio of flanges and webs are proportioned in such that the premature local buckling of flanges and webs prior to achievement of the full strength of plate-girders must be prevented. It is the common practive in most design codes that the flange local buckling strength and the web bend buckling strength are separately computed. In most practical plate girders, however, the flange buckles simultaneously when web bend-buckling occurs, vice versa. The primary purpose of the present study is to investigate the phenomenon, which may be called flange-web interactive buckling. Using the eight-node shell element available in the commercial multi-purpose program ABAQUS, the phenomenon was quantitatively investigated. Also presented are the effects of various factors such as the ratio of flange slenderness ratio to the web slenderness ratio, the ratio of flange width to the web depth, and the longitudinal stiffeners. A series of comparative studies with various design codes show that the present study provides more accurate and effective design basis in proportioning the flanges and webs.

• Structural Engineering and Mechanics
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• v.24 no.3
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.