• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.96-104
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• 2005

The coupled vibration characteristics for the fluid-structure interaction systems are investigated through the finite element method. The present paper is focused on vibration characteristics of the cylindrical fluid-storage tank with a baffle. The tank is partially filled with an inviscid and irrotational fluid having a free surface. A baffle is assumed here to have the shape of a thin annular plate and a conical shell, attached to the cylindrical tank and positioned below the fluid surface. The liquid domain is limited by a rigid flat bottom. As the effect of free surface waves is taken into account in the analysis, the bulging and sloshing modes are studied. To demonstrate the validity of present results, they are compared with the published ones. The effect of positions and inner-to-outer radius ratio of annular baffle and setting angles of conical baffle on coupled vibration characteristics is investigated.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.41-47
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• 2004

Plate has cutout inner bottom and girder and Door etc. in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and freight movement, piping etc.. Because cutout‘s existence is positioning in this place, and, elastic bucking strength by load causes large effect in ultimate strength. Therefore, perforated plate elastic bucking strength and ultimate strength is one of important design criteria to decide structural elements size at early structure design step of a ship. Therefore, we need reasonable & reliable design formula for elastic bucking strength of the perforated plate. The author computed numerically ultimate strength change about several aspect ratios, cutout dimension, and plate thickness by using ANSYS Finite element analysis code based on finite element method in this paper.

• Journal of Forest and Environmental Science
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• v.8 no.1
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• pp.51-66
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• 1992

This study was carried out to investigate the micromorphology of vessel wall sculpture such as shape of perforation plate, perforation rim, steepness of perforation plate, occurrence of vestured pit, warty layer and ray-vessel pitting on 13 species of Fagaceae in Korea. The results were summarized as follows ; 1. In the species examined, all sample species except Fagus crenata var. multinervis have simple perforation plate. But Fagus crenata var. multinervis has simple and scalariform perforation plate (it was called to combination perforation plate) in a tree stem. 2. The shapes of perforation rim could be classified into five types; Type A without tail, Type B with small tail on both sides, Type C with long tail on both sides, Type D with tail only one side and Type E with the very short interval between perforations. Among five types, Type Band C have higer frequency of distribution than the others. 3. The steepness of perforation plate measured was about 20 degree on pore zone and 43 degree on outside parts of pore zone. 4. Species with vestured pit were Q. aliena, Q, dentata, Q. variabilis, Fagus crenata var. multinervis, Castanopsis cuspidata var sieboldii, Q. acuta, Q. stenophylla, and Q. glauca. But the extent of vesturing was very slight and vestured pits were observed mainly in ray-vessel pit of some vessel elements. 5. Species with warty layer on the inner surface wall of all vessel elements were Q. acuta, Q. stenophylla, Q. glauca, Fagus crenata var. multinervis and species with warty layer of some vessel elements were Q. aliena, Q, dentata, Q. variabilis, Castanopsis cuspidata var. sieboldii. 6. Species with palisade ray-vessel pit were Q. acuta, Q. stenophylla, Q. glauca, Castanea crenata, Castanea bungeana, Q. aliena, Q. serrata, Q. mongolica, and species with scalariform ray-vessel pit was Fagus crenata var. multinervis and species with oval ray-vessel pit were Q, dentata, Castanopsis cuspidata var sieboldii.

• Special Issue of the Society of Naval Architects of Korea
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• 2015.09a
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• pp.56-62
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• 2015

In ship structure, many parts are in contact with inner or outer fluid as stern, ballast and oil tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these tanks in contact with fluid are significantly affected by fluid coupling effect. Therefore it is important to exactly predict vibration characteristics of tank structure. In order to estimate the vibration characteristics, the fluid-structure interaction(FSI) problem should be solved precisely. But it is difficult to estimate exactly the magnitude of the fluid coupling effect because it has some problems such as a fluid-structure interaction, influence by the free surface, vibration modes of structural panels and depth of water. In this paper, with fluid coupling effect, the effect of structural constraint between panels on the vibration characteristics are investigated numerically and discussed.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.435-445
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• 2007

Ship structures are thin-walled structures and lots of cutouts, for example, of inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed. In the present paper, we investigated several kinds of perforated stiffened model from actual ship structure and series of elasto-plastic large deflection analyses were performed to investigate into the influence of perforation on the buckling and ultimate strength of the perforated stiffened plate varying the cutout ratio, web height, thickness and type of cross-section by commercial FEA program(ANSYS). Closed-form formulas for predicting the ultimate strength of the perforated stiffened plate are empirically derived by curve fitting based on the Finite Element Analysis results. These formulas are used to evaluate the ultimate strength, which showed good correlation with FEM results. These results will be useful for evaluating the ultimate strength of the perforated stiffened plate in the preliminary design.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.129-135
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• 2004

Plate has cutout inner bottom and girder and floor etc in hull construction absence is used much, and this is strength in case must be situated, but establish in region that high stress interacts sometimes fatally in region that there is no big problem usually by purpose of weight reduction, a person and change of freight, piping etc. Because cutout's existence gnaws in this place, and, elastic budding strength by load rouses large effect in ultimate strength. Therefore, perforated plate elastic budding strength and ultimate strength is one of important design criteria which must examine when decide structural elements size at early structure design step if ship. Therefore, and, reasonable elastic budding strength about perforated plate need design ultimate strength. Calculated ultimate strength change several aspect ratioes and cutout's dimension, and thickness in this investigation. Used program applied ANSYS F.E.M code based on finite element method

• Advances in concrete construction
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• v.14 no.3
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• pp.195-204
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• 2022

As a brittle failure mode, punching-shear failure can be widely found in traditional RC slab-column connections, which may lead to the entire collapse of a flat plate structure. In this paper, a novel RC slab-column connection with inner steel truss was proposed to enhance the punching strength. In the proposed connection, steel trusses, each of which was composed of four steel angles and a series of steel strips, were pre-assembled at the periphery of the column capital and behaved as transverse reinforcements. With the aim of exploring the punching behavior of this novel RC slab-column connection, a static punching test was conducted on two full-scaled RC slab specimens, and the crack patterns, failure modes, load-deflection and load-strain responses were thoroughly analyzed to explore the contribution of the applied inner steel trusses to the overall punching behavior. The test results indicated that all the test specimens suffered the typical punching-shear failure, and the higher punching strength and initial stiffness could be found in the specimen with inner steel trusses. The numerical models of tested specimens were analyzed in ABAQUS. These models were verified by comparing the results of the tests with the results of the analyzes, and subsequently the sensitivity of the punching capacity to different parameters was studied. Based on the test results, a modified critical shear crack theory, which could take the contribution of the steel trusses into account, was put forward to predict the punching strength of this novel RC slab-column connection, and the calculated results agreed well with the test results.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.771-777
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• 1999

The structural function of three egg membrane layers and cuticle layer, and the effectiveness of 5 film coatings (chitosan, starch, gelatin, dextrin, mineral oil) on the prevention of Salmonella enteritidis penetration was investigated using confocal scanning laser microscopy (CSLM). Diameters of outer membrane fibers, inner membrane fibers and limiting membrane particles in eggshell were $1.5{\sim}7.2$, $0.8{\sim}2.0$ and $0.1{\sim}1.4\;{\mu}m$, respectively and average thicknesses were 10.0, 3.5, $3.6\;{\mu}m$, respectively. Average thickness of cuticle layer was $6.0\;{\mu}m$ and cuticle layer covered $40{\sim}80%$ of total eggshell surface. Average coating films thickness for chitosan, starch, gelatin, dextrin and mineral oil were 2.2, 2.5, 3.9, 3.6 and $5.0\;{\mu}m$, respectively. After immersion process eggshell surface was almost completely covered by coating films. Chitosan coating was most effective among 5 film coatings in inhibiting growth of Salmonella enteritidis. Penetration process of Salmonella enteritidis through eggshell was investigated by multicolor imaging using CSLM and plate counting. Cuticle layer was the most important structure in blocking the penetration. Among 5 film coatings, chitosan showed the best and similar effectiveness with cuticle layer.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.166-176
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• 1994

Ni base superalloys are composed of solid sohltion hardening elements(Co, Cr. Mo. W and so on) and $\gamma '$ precipitation hardening elements(A1, Ti, Nb, Ta and so on). To Improve the mechanical properties and oxidation resistanre of superalloys, rare earth elements(%r, Hf, Y and so on) are added to the inner substrate, or are used as coating materials. Their pffects on the growth rate and adhes~on of oxide are changed according to the kinds of oxides such as $AI_2O_3$ and $Cr_2O_3$. The effect of yttrium on the oxidation rate, grain size of oxide, internal structure, and crack resistance was investigated for two kinds of Ni-base superalloys. One in AF'115 superalloy containing Hf and the other is MA6000 superalloy containing $Y_2O_3$. They werr owid~zed at high temperature after yttrium surface modification using ion coater. Yttrium coating on the AF115 and MA6000 superalloys results in a marked change in the growth of the inner oxide. For AF115 superalloy, the degree of gram boundary segregation of $Cr_2O_3$, and prefer en^ tial oxidation of Hf are decreased, and the shape of inner oxidation layer was changed from triangle to plate type. For MA6000 superalloy, $Cr_2O_3$ oxide scale was transformed as outer oxidation layer of CrZOI and inner oxidation layer of $Cr_2O_3$.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.125-138
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• 1991

In this paper, an efficient method for the analysis of damage and strength of double bottom structure in stranding is described by using idealized structural unit method. Also a procedure for the determination of the effective double bottom height which is required in order to protect the inner-bottom plate is proposed. In the comparison between the present solution and he existing experimental and numerical results in stranding, its observed that the present method gives reasonable results requiring very shorts computiong times. The present method is then applied to the double bottom structure of 40K product oil carrier which is designed by the double skin design concept as an example. By performing the series of analysis, the influence of vertical member space, plate thickness and double bottom height on the energy absorption capacity of the double bottom structure in stranding is investigated. Also the minimum double bottom height with varying each design variable Is calculated based on the above result.