• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.34-40
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• 2012

In this study, effects of bonding agent, e.g. epoxy, on the behavior of fundamental guided wave modes propagated in FRP plate bonded on a concrete, are investigated. Global matrix model of multilayered FRP-epoxy-concrete system was constructed to obtain the velocity and attenuation dispersion curves of the fundamental A0 and S0 modes. Two variables, thickness and elastic modulus of epoxy layer, were considered in the dispersion analysis. It was found that both the thickness and the elastic modulus of epoxy layer greatly affect the phase velocity and attenuation of S0 mode while those are negligible for A0 mode. Based on the results, it was concluded that S0 mode is more effective than A0 mode for bonding condition assessment for FRP plate bonded concrete.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.6-10
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• 1997

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.5
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• pp.17-26
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• 2011

Drying behavior and physical properties of HwBKP, SwBKP, and OCC handsheets depending on kneading, refining and wet pressing were analyzed. The maximum drying shrinkage velocity was newly adopted to verify the effect of mechanical treatment of pulps by evaluating drying behavior according to varying the kneading, refining and wet pressing treatments. Those various treatments were changed to evaluate the relationship between the maximum drying shrinkage velocity and handsheets properties. When the drying shrinkage and the maximum drying velocity increased by refining and wet-pressing, handsheets strength was increased. The maximum drying shrinkage velocity showed higher correlation with physical properties of paper than WRV at different refining loads at SwBKP and mixed pulp. At high wet-web dryness, drying shrinkage, the maximum drying shrinkage velocity and strength properties of handsheet were increased. It meant that drying shrinkage behavior was highly affected by not only fibers' shrinkage but also fiber bonding. Kneading pre-treatment for KOCC and SwBKP effectively modified fiber properties and increasing paper strength and drying shrinkage. The effect of kneading pre-treatment was also confirmed by the maximum drying shrinkage velocity. Strength properties of mixed pulp handsheets were not increased by the kneading pre-treatment, although the maximum drying shrinkage velocity and WRV was increased. It meant that fibers network bonding of HwBKP was limited because of ves sels and ray cells' interference for bonding. Therefore in order to improve paper strengths containing HwBKP by mechanical treatments, interference of vessels and ray cells for fiber bondings should be carefully controlled.

• Transactions of Materials Processing
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• v.14 no.1 s.73
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• pp.71-77
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• 2005

Thermal stability and dry sliding wear behavior of ultra-fine grained 6061 Al alloy fabricated by an accumulative roll-bonding (ARB) process have been investigated. After 4 ARB cycles, an ultra-fine grained microstructure of the 6061 Al alloy composed of grains with average size of 500nm, and separated mostly by high-angle boundaries was obtained. Though hardness and tensile strength of the ARB processed Al alloy increased with ARB cycles up to 4 cycles, the processed alloy exhibited decreased ductility and little strain hardening. Thermal stability of the ARB-processed microstructure was studied by annealing of the severely deformed alloy at $423K{\sim}573K$. The refined microstructure of the alloy remained stable up to 473K, and the peak aging treatment of the alloy at 450K for 8 hrs increased the thermal stability of the alloy. Sliding-wear rates of the alloy increased with the number of ARB cycles in spite of the increased hardness with the cycles. Wear mechanisms of the ultra-fine grained alloy were investigated by examining worn surfaces, wear debris, and cross-sections by a scanning electron microscopy (SEM).

• Journal of the Korean Dietetic Association
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• v.19 no.2
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• pp.140-158
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• 2013

This study analyzed the effect of family meals on the psychological problems of children. We performed focus group interviews (FGI) on the basic characteristics of family meals, and chose several scales (such as Child Behavior Checklist (CBCL), self-esteem, and a daily hassles questionnaire), to measure the psychological variables. We collected data from 442 dyads (mother-child) and used 440 from dyads. In our results, the frequency of family meals affected the psychological problems of children, especially aggression and emotional instability. The atmosphere during meals also affected depression/anxiety, concentration difficulties, emotional instability, self-esteem, peer relationships, and sociality. There were significant correlations between meal atmosphere, family bonding, maternal personality, and psychological problems of children. We performed covariation analysis to examine and control the influence of family bonding and maternal personality; despite controlling for these variables, family meals still influenced children's psychological problems. We conclude that the family meal is a significant variable that impacts the emotional and behavioral problems of children and stress the importance of frequent family meals.

• The Journal of Information Systems
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• v.25 no.1
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• pp.201-223
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• 2016

Purpose As social network games (SNG) enjoy rapid growth in the market and become a major sector of the gaming industry, it is of great interest to examine the how users continuously use SNG. In SNG, the users' social interaction is the most prominent advantage of the social network, as well as the entertainment afforded by the game. This study explores the relationship between altruism, which is considered the most prominent characteristic of SNS, and the continuance usage intention, as well as the moderating role of social capital. Based on social capital theory and organizational citizenship behavior, this research model considers social bonding and bridging that are divided by social capital. Design/methodology/approach An AMOS analysis based on survey data from 223 SNG users indicated that SNG with greater altruism enhance social capital (social bonding, social bridging), which is related to the user's satisfaction and the continuance intention of SNG. Findings Social bonding is positively related to the user's satisfaction with SNG. In other words, social bridging positively affects the continuous usage intention of SNG. These findings help managers in developing and implementing altruistic relationships and social capital for continuous usage of SNG.

• Journal of Korean Association for Spatial Structures
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• v.22 no.4
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• pp.99-107
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• 2022

Existing reinforced concrete building structures constructed before 1988 have seismically-deficient reinforcing details, which can lead to the premature failure of the columns and beam-column joints. The premature failure was resulted from the inadequate bonding performance between the reinforcing bars and surrounding concrete on the main structural elements. This paper aims to quantify the bond-slip effect on the dynamic responses of reinforced concrete frame models using finite element analyses. The bond-slip behavior was modeled using an one-dimensional slide line model in LS-DYNA. The bond-slip models were varied with the bonding conditions and failure modes, and implemented to the well-validated finite element models. The dynamic responses of the frame models with the several bonding conditions were compared to the validated models reproducing the actual behavior. It verifies that the bond-slip effects significantly affected the dynamic responses of the reinforced concrete building structures.

• International Journal of Automotive Technology
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• v.6 no.6
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• pp.657-663
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• 2005

Recently, weight reduction of vehicles has been of great interest, and consequently the use of composite materials in the automotive industry is increasing every year. Composite sandwich panels which consist of two skins and core materials are replacing steels in automotive floor and door. The substitution of one material for another is accompanied by change of joining method, so that adhesive bonding has been popularly used for joining method of composite materials. In the case of adhesive bonding of composite materials, there could be loss in the joint strength by delamination of two faceplates or cracking on faceplate. Thus, it is necessary to prevent loss in the joint strength by designing the joint geometry. In the present paper, adhesive bonding of aluminum sandwich sheet was tried. For understanding joint behavior, studies on stresses in the single lap joint were reviewed and failure modes of composite material were analyzed. Strength tests on the single lap joint consisting of aluminum sandwich sheet and steel were performed and variation of the joint strength with the joint configuration was shown. Based on these results, design guide of adhesive bonding in aluminum sandwich sheet was suggested.

• Korean Journal of Child Studies
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• v.26 no.6
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• pp.189-200
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• 2005

The main objectives of this study are to examine the relationships among the Bu-Ja- Yu-Chin-SungCheong, child's self differentiation and interpersonal relationship and to compare the effects of the cultural virtues. Bu-Ja-Yu-Chin-Sung-Cheong which is the Korean traditional parent-child affective bonding defined as a characteristic of relationship between parents and children within Korean culture by Choi, sang jin. The subject of the study are 656 students from 4 different elementary schools in Seoul : they were 5 and 6th grades. The study was executed by surveying them with questionnaire and the results were analyzed through co-relation analysis and multiple regression. Findings were: (l)the Korean traditional parent-child affective bonding has a positive effect on self differentiation and interpersonal relationship of a child. (2)The Korean traditional bonding has a impact on a child's acceptance of others and social behavior. However, according to the level of a child's self differentiation a child's dominance-ascendance, ostentation-narcism interpersonal relationship inclination increased.

• Textile Coloration and Finishing
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• v.25 no.2
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• pp.110-117
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• 2013

The purpose of this study is to fabricate the flame retardant polyester fabric by thermal bonding with low melting component of flame retardant bicomponent filament(LMFRPC) and to describe the characteristics of thermal bonded fabrics. The fabrics were prepared with flame retardant polyester filaments(FRP) as warp and blended filaments of FRP and LMFRPC as weft. The LMFRPC have a sheath and a core wherein the core comprises a flame retardant polyester and the sheath comprises a thermoplastic polyester of low-melting point. In this study, we investigated the physical properties, melting behavior of filament, the effect of the component of FRP and LMFRPC on the thermal bonding, mechanical properties. Melting peak of LMFRPC showed the double melting peak. The thermal bonding of the fabric formed at lower melting peak temperature of bicomponent filament of LMFRPC. The optimum thermal bonding conditions for fabrics was applied at about $170^{\circ}C$ for 60 seconds by pin tenter. On the other hand, the tensile strength, elongation, and LOI of the fabric increased with an increasing component of FRP of weft.