• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.5
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• pp.423-430
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• 2012

In this paper, the effect of wrinkling on the cut propagation direction of thin membrane was studied using geometrically nonlinear shell element post-buckling analysis. In the analysis, rectangular tensile membrane configuration with a slanted center cut was considered. The cut propagation direction was predicted by maximum energy release rate method, $K_{II}$-zero method, and maximum tangential stress method. The cut propagation angle and the $J$-integral values were calculated for the wrinkled and unwrinkled cases and the results were compared. Various initial cut orientation angles were considered and the effect on the propagation direction was studied. The cut propagation paths were also predicted by virtual cut extension approach.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.940-949
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• 2013

In this paper, wrinkle reduction design was studied for triangular sail. Wrinkles in the solar sail membrane can change the load path and surface topology which may have an adverse effect on propulsion performance and controllability. In this study, wrinkle reduction strategies of adjusting cable angle, catenary and catenary-wire schemes were considered and the design parameters for wrinkle reduction were systematically investigated.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.39-43
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• 2011

In this study, the stress and deformation behavior characteristics of a flexible joint for a gas pipe have been analyzed by a finite element method. These characteristic results may investigate the strength safety analysis of a flexible joint, which is composed by a spiral corrugation pipe or a rectangular corrugation model and a plane pipe. The FEM computed results show that an optimized spiral corrugation pipe model is a inclined angle of $4.7^{\circ}$ and a corrugation height of 1.5mm. And also, a rectangular corrugation pipe model of $90^{\circ}$ is recommended in strength safety rather than a spiral corrugation pipe with an inclined angle. Thus, a corrugated pipe for an increased strength safety is to recommend a reduced pitch and curvature radius of an inclined corrugation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.154-159
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• 2012

For numerical analysis of the plate heat exchanger, a lot of time are required in modeling work and calculation. Whereas, this paper was purposed to identify characteristic of the plate heat exchanger through simplification of modeling by interpreting the numerical analysis proximity with the actual model. This study was also examined temperature difference between inlet side and outlet side, inner pressure drop, heat transfer area of plate and change of heat transfer coefficient on the plate depending on the inner corrugation angle and corrugation pitch of a herring bon pattern of the plate heat exchanger among chevron types of the plate exchanger.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.851-858
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• 2008

In this paper, the wrinkling behavior of vertically creased corner-loaded square membranes was studied using geometrically nonlinear post-buckling analysis. The membranes were modeled using shell elements, and the meshes were seeded with semi-random geometrical imperfection to instigate the buckling deformation. A pristine and creased membranes with various initial deployment angles were considered in the analyses and the results were compared. Results showed that local wrinkles initiated near the corner where the higher load was applied, which grew to form a single diagonal global wrinkle as the load ratio increased. It was also found that the local wrinkle initiation and the global wrinkle formation were significantly dependent on the initial deployment angles.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.195-203
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• 2015

In this paper, the dynamic behavior of wrinkled triangular solar sail was studied by finite element analysis. The analysis was proceeded first by performing static wrinkle analysis under tensile corner load on sail membrane, and then performing modal analysis. The membrane element method with wrinkle algorithm and the shell element post-buckling analysis method were used to account for the wrinkle deformation and the results were compared for analysis methods throughly. The comparison was also made to that without wrinkle consideration to investigate the effect of wrinkle deformation on the results. Cases with various loading cable angles were analyzed and the results were systematically examined.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.134-138
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• 2021

Various types of precision plastic thin films are used widely in high-performance displays, such as smartphones. For plastic thin-films manufactured by the Roll-to-Roll process, the film thickness must be measured and managed while moving. In the Roll-to-Roll process, wrinkles are generated when tension is applied to the film, which causes an inclination on the optical axis of the thickness gauge, resulting in a loss of accuracy. Therefore, this study attempted to develop an optical interference tomography measurement system. In this study, the tilt angle of the film was measured to correct the measurement value error in the thickness gauge caused by the tilt of the film. The system was constructed so that the laser was irradiated on the tilted film, and the laser reflected from the film was formed on the PSD. The relationship between the tilt angle of the film and the output value of the PSD was obtained experimentally. Using this, a device to measure the tilt angle of the film was constructed, and angle measurements were taken at a speed of 250,000Hz.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.7
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• pp.588-594
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• 2001

The purpose of this study is to investigate the thermal and hydrodynamic characteristics of the channel in corrugated plate type heat exchangers numerically. Numerical work has been conducted using the Reynolds Stress Model(RSM) by utilizing the commercial finite-volume code, FLUENT. Based on this model, the dependence of heat transfer and friction factor on geometrical parameters have been investigated. It is found that larger corrugation angle give higher values of heat transfer coefficients and friction factors. As the reynolds number increases, the heat transfer coefficient also increases. It is also observed that the heat transfer coefficient reaches maximum while the friction factor stays relatively low at same corrugation angle. Through the analysis, it is found that the optimum corrugation angle for the heat exchanger performance exists. It is noted that the flow repulsions at the contact point of the two fluid streams make the low mixing more active for larger corrugation angle and high reynolds number.

• Fashion & Textile Research Journal
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• v.1 no.3
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• pp.252-258
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• 1999

The aims of this study is to classify the lower somatotype of adult women and appearance analysis on the shape of flare skirts by using the image processing. Also We have made skirts in order to analyze the various types of appearance of flare skirts by using the image processing. The subjects for our wear test lower somatotype, who were controlled in their waist, abdomen and hip shapes. The flare skirts used for wear test were 112 types(combinated 14 fabric type and 8 lower somatotype). The effect of lower somatotype on the shape of flare skirts was determined by the horizontally hem line section shape and the silhouette of flare skirts with image processing. The data were analyzed by using analysis of variance and Turkey, Duncan multiple range test. The results obtained are summarized as follows: It is shown that the fabric weight elongation differs in fabrics properties, in direction of textures. The shape horizontal section of flare skirt hem line has differed with the number of nodes, wave-height of nodes and breadth of silhouette by fabrics properties and lower somatotype. It is noticed that the breadth of flare skirts by the silhouette has high correlation with the drape ability of fabrics and lower somatotype. Results for our flare skirts show changes in amplitude and mean with fabrics, somatotype. Therefore we can say that gray-level histograms are correlated with changes in appearance, differences in drape spacing and related fabric properties and their somatotype.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.11-18
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• 1991

Stiffened plate structure, which is generally used in the various structural design to develope the load carrying capacity, is classified in two groups; one is the plate stiffened with stiffeners, the other is corrugated plate. In the studies on those structures, the studies on the stiffened plates with stiffeners have been much studied with both quantities and qualities according to requirements of the minimum-weight structural design and the development in many industrial fields, especially automobile, ship and aerospace fields, but the studies on the corrugated plates are undeveloped in comparison with the stiffened plates, and also the analytical stiffness on the corrugated plates remains as the imperfect. In the present studies, the analytical method on the stiffness of corrugated plates made by folding is proposed, and the stiffness equation of corrugated plates with some angle is derived and generalized. The purpose of the present study is to contribute to the design of corrugated plates and to determine the optimum aspect ratio for parameters that decide the aspect of corrugated plates.