• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.3
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• pp.268-279
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• 2007

The reliability of cold-bonding repair technique of carbon-fiber reinforced plastics (CFRP) laminates, often used as a temporary repair for the airplane maintenance, has been evaluated during cyclic loading and localized heating by nondestructive methods. Major concern was given to the evolution of damage after repair in the form of delaminations due to localized heating and cyclic loading combined. An area of interest both on the specimen repaired by cold-bonding and the specimen without repair where delaminations were induced by localized heating and cyclic loading was monitored by acoustic emission (AE) testing and further examined by pitch-catch low-frequency bond testing, and pulse-echo high-frequency ultrasonic testing. The results showed that the reliability of cold-bonding repair would be significantly reduced by the localized heating and cyclic loading combined rather than by the cyclic loading only. AE monitoring appeared to be an effective and reliable tool to monitor the integrity of temporarily repaired CFRP laminates in terms of the structural health monitoring (SHM) philosophy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.374-377
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• 2005

Automobile is in charge of most transportation system in modern urban city. However, in fact, cause of problem of road state, environment, and the other reasons, urban transit system is using as Mass Transit nowadays. Nevertheless Urban transit system is considering many kind of safety fact of that system which is increasing continuously nowadays, it occurs various train accident. This paper describes 3D Dimensional Measurement(EDM testing) and tensile testing results of carbody structure for crashed EMU(Electric Multiple Units). Tensile tests were performed on two different types of specimens in order to evaluate the strength changes before and after damages, obtained from plastic deformed area and nondeformed region of the crashed EMU. And Structural analysis of EMU was performed for the criteria of safety assessment. Structural analysis using commercial I-DEAS software provided important information on the stress distribution and load transfer mechanisms as well as the amount of damages during rolling stock crash. The testing results have been used to provide the critical information for the criteria of safety diagnosis.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.20-26
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• 2014

This paper represented the finite element analysis to estimate structural performance of stress-laminated deck, which is determined by deflection, stress, and aging characteristics of tensioning. After loading, the deflected shape showed plate behavior because pre-stressing make frictional force between each member. Compared between initial post-tension and the results, pre-stressing forces were decreased with deck deflection. This is because deflection occurred in the deck so that pre-stressing decreased due to load reduction. However, material plasticity was not considered so that advanced researches should be performed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.2
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• pp.145-152
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• 2009

In this paper, dynamic instability of plane membrane structures under wind action has been studied. The key to solving the governing equations of membrane structures under wind action is how to obtain the air pressure on membrane. Based on Bernoulli's theorem, fluid pressure has a certain relationship with velocity potential. Velocity potential could be solved according to thin aerofoil theory, where air around the membrane is regarded as a sheet of vortices. In this paper, we take advantage of the most commonly used three-node triangular membrane element and weighted residual-Galerkin method to obtain the determining equation for stability evaluation. Square and rectangular membrane structures are studied. The influence of initial prestressing force and wind direction towards critical wind velocity are also analyzed in this paper.

• Korean journal of food and cookery science
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• v.27 no.2
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• pp.83-94
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• 2011

The purpose of this study was to analyze the structural relationships among selection attributes, satisfaction, and loyalty of green tea consumers, including their moderating effect of involvement. Questionnaires were administered to residents of Seoul and Gyeonggi-do province, who were 20 years old and older and who had purchased green tea. A total of 700 questionnaires were distributed, and 658 were finally used in the analysis. SPSS 15.0 and LISREL 8.80 were used for the analysis. Selection attributes had a significant effect on satisfaction, and statistical significance was observed with regard to factors such as marketing, production, sensory evaluation, and brand. No significant direct effect was observed between selection attributes and loyalty. Additionally, satisfaction had a significant effect on loyalty. The marketing factor had a negative effect on satisfaction in both the low- and high-involvement groups. The brand factor had a positive effect on satisfaction in the low involvement group, suggesting that developing and promoting a popular brand is essential. Sensory and utility factors had a positive effect on satisfaction in the high involvement group.

• Korean Journal of Human Ecology
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• v.14 no.4
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• pp.665-671
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• 2005

This study aims to examine the effect of structural properties, subjective textures, sensibilities, and objective handle on the preference for weft knit fabrics, and then to provide useful information in planning and designing knit fabrics through predicting the preference. We made 20 plain knit fabrics, as specimens, with a combination of 5 kinds of wool/rayon fiber contents and 4 kinds of stitch loop length. For the subjective evaluation of textures, sensibilities, and preference, we used the questionnaire that had been developed in the previous study. The data analysis was conducted with Pearson's correlation analysis, ANOVA, Duncann multiple range test and regression analysis. The results are as follows: In relationship of structural properties and preference, we could not recognize any difference in whole ranges of wool/ rayon fiber contents and in 7.5mm and less stitch loop length. On the other hand, we could find the decrease of preference in over 7.5mm stitch loop length. As to subjective textures and sensibilities, a multiple regression analysis of preference indicated a higher determination coefficient by sensibilities than by textures. But there were little correlation between a objective handle and preference of weft knit fabrics.

• Journal of the Korean Institute of Rural Architecture
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• v.11 no.2
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• pp.29-36
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• 2009

The recently research shows that the many tourists of Suanbo hot spring waters haven't satisfied the service. These reasons due to that they did not properly consider the satisfaction of tourists' services and index. However, satisfaction level of hot spring waters tourists is interacted complicatedly with various factors, the interactions are not easily identified. A structural equations model is adopted to capture the complex relationships among variables. In the model estimation, we used 140 survey data of Suanbo hot spring waters tourists. The SEM with several factors mentioned above as exogenous variables shows that they have complex and strong relationships. As results of a SEM, it was shown that variables influencing in pleasance are surrounding scenery, clean condition inside hot springs and congestion for use in satisfaction level most. Secondly, in case of kindness, attitudes of employees influence in satisfaction level most, followed by attitudes of residents and kindness of employees. Thirdly, in case of information, it was shown guidance on internal roads influencing in satisfaction level most, followed by guidance on owner drivers, guidance on surrounding tourist attractions and guidance on public transportation. Finally, a variable influencing in accessibility most is satisfaction level of public transportation.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.485-491
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• 2015

In this study, the experimental and analytical investigation on structural integrity evaluation of spline shaft of self propelled artillery' generator were carried out. For this work, macro and microstructure fractography of spline shaft were observed. According to the results of the structure analysis and simulation, the shaft was redesigned and optimized. To improve the stiffness and shear stress, the material was changed from the SNCM220 to SNCM439 and surface roughness and protective coating treatment are changed to increase the stress relaxation, respectively. From the result of the torsion test of shaft and accelerated life test of generator, the shaft of a SNCM439 with heat-treatment(Q/T) and electroless nickel plating was superior quality reliability and durability than the others. Therefore, modeling and simulation corresponded well with the experimental result and structural safety was confirmed by generator performing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.396-406
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• 2009

In extension to our previous study, we develop metadata that specify elements' structural orders, to increase the efficiency level of XML document's retrieval process. Then, we proposed a structure-based indexing model. We expect the model to generate a more efficient retrieval process of horizontally and vertically related elements. To evaluate the model's performance level, we developed an experimental prototype and conducted an experiment on an XML corpus. On average, descendant, ancestor and sibling retrievals were approximately twelve percent faster than the ETID model. And retrievals specifying structural orders of particular element types were approximately twenty-five percent faster than the ETID model. In conclusion, metadata, such as Etype, Asso and Lsso, may make a meaningful contribution to retrieval processes that specify elements' order.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1216-1224
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• 2000

The collapse pressure of tubes is determined experimentally by Tschoepe and Maison for various materials with different geometries. The results are compared with those obtained by ASME Codes UG-31 and UG-28. A collage pressure is the pressure required for the incipient yielding stress of the tubes with and without ovality. This collapse pressure is compared with the experimental results by Tschoepe and Maison. The present investigation is towards finding the collapse pressure required to bring the entire wall of tubes into a state of plastic flow for the pipes, with ovality and without ovality. This collapse pressure is compared with the collapse pressure obtained through experiments in the present investigation. The experimental results are compared with the pressure obtained by FEM(finite element methods). The FEM results are then compared with results obtained through an approximate plastic analysis of the strain hardening material, SA312-TP304 stainless steel. The structural integrity evaluation is performed for the heat exchanger used in an actual nuclear power plant by using various methods described in this paper. The results obtained by the various analyses and the FEM are discussed. consequently, the paper is oriented towards an actual design purpose of d heat exchanger in an industrial environment, rather than for the purpose of an academic research project investigation.