• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.84-91
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• 2013

Ultrasonic flip-chip bonding needs a precise bonding tool which delivers ultrasonic energy into chip bumps effectively to use the selected resonance mode and frequency of the horn structure. The bonding tool is excited at the resonance frequency and the input and output ports should locate at the anti-nodal points of the resonance mode. In this study, we propose new design method with topology optimization for ultrasonic bonding tools. The SIMP(solid isotropic material with penalization) method is used to formulate topology optimization and OC(optimal criteria) algorithm is adopted for the update scheme. MAC(modal assurance criterion) tracking is used for the target frequency and mode. We fabricate two prototypes of ultrasonic tools which are based on 3D optimization models after reviewing 2D and 3D topology optimization results. The prototypes are satisfied with the ultrasonic frequency and vibration amplitude as the ultrasonic bonding tools.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.467-468
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• 2012

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1134-1135
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• 2006

A revolutionary "Active Braze Coated Diamond" (ABCD) has been developed for bonding diamond grits firmly in the metal matrix. The molten braze is wetted and reacted with diamond to form strong chemical bond at the interface so that the diamond does not become knocked out of tools. The ABC is a nickel alloy that can form metallurgical diffusion bondswith the metal matrix. In essence, ABCD turns diamond into a metal grain so that the diamond tools can be made by conventional powder metallurgical process without being concerned about the poor bonding between matrix metal powder and the diamond as before.

• Korean Parent-Child Health Journal
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• v.6 no.2
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• pp.93-102
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• 2003

The study was designed to examine the effect of perceived past parent-child bonding on present parent-child attachment, self-concept. The data collection period was October 6-18, 2003. The subject was college students in university located in Nonsan, Taejon city and 197 surveys were used in the analysis. As for the tools used in this study to assess the perceived past parent - child bonding scale by Parent Bonding Instrument - Korean Version, and present parent-child attachment were measured with the The Inventory of Parent and Peer Attachment, and self-concept were measured with Jung, Won Sik's self-concept inventory. For the data processing, the analyses of variance, multiple regression, correlation were carried out. The result of this study is summarized as follows. 1. The examination of the effect of perceived past parent-child bonding on present parent-child attachment showed that significant differences are made by communication, trust, alienation in care, overprotection perceived past parent-child bonding. 2. As for the correlation between perceived past parent-child bonding and child self-concept, a significant correlation is revealed between care, overprotection perceived past parent-child bonding and child self-concept.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.402-407
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• 2002

Laminate tooling process is a fast and simple method to make metal tools directly for various molding processes such as injection molding in rapid prototyping field. Metal sheets are usually cut, stacked, aligned and joined with brazing or soldering. Through the joining process, all of the metal sheet layers should be rigidly joined. When joining process parameters are not appropriate, there would be defects in the layers. Among various types of defects, non-bonded gaps of the tool surface are of great importance, because they directly affect the surface quality and dimensional accuracy of the final products. If a laminate tool with defects has to be abandoned, it could lead to great loss of time and cost. Therefore a repair method for non-bonded gaps of the surface is essential and has important meaning for rapid prototyping. In this study, a rapid laminate tooling system composed of a CO2 laser, a furnace, and a milling machine was developed. Metal sheets were joined by furnace brazing, dip soldering and adhesive bonding. Joined laminate tools were machined by a high-speed milling machine to improve surface quality. Also, repair brazing and soldering methods of the laminates using the $CO_2$ laser system have been investigated. ill laser repair process, the beam duration, beam power and beam profile were of great importance, and their effects were simulated by [mite element methods. The simulation results were compared with the experimental ones, and optimal parameters for laser repair process were investigated.

• Journal of The Korean Association For Science Education
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• v.43 no.2
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• pp.181-190
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• 2023

In this study, we compared discourse by environments for using tools in terms of participation types, discourse types, and knowledge building processes. 24 first-year high school students were divided into six groups. They were assigned to the sharing tools environment, which used one marker and one smart device, or the individual tools environment, which used markers and smart devices individually. Students participated in small group learning using AR application based on the concept of chemical bonding. All classes were video- and audio-taped. Semi-structured interviews were conducted with six students who voluntarily agreed. The results of the study revealed that the sharing tools environment had a high proportion of one-student dominating type, while the individual tools environment had a high proportion of partly participating type and most students participating type. In the individual tools environment, the ratio of knowledge sharing and knowledge construction discourse was similar compared to the tool sharing environment, and the sub-discourse types were also diverse. In the sharing tools environment, only some students had a meaningful knowledge building process. On the other hand, in the individual tools environment, most of the group members constructed knowledge about the target concept, and had a meaningful knowledge building process. In addition, the misconceptions that appeared to some group members were corrected through small group discussions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.25-30
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• 2015

This study involved the fabrication of precision machine tools using a polycrystalline diamond tip [sintered PCD and cemented carbide (WC-Co) tip] and WC-Co shanks via diffusion bonding with a paste-type nickel alloy filler metal. Diffusion bonding is a process whereby two materials are pressed together at high temperature and high pressure for a sufficient period of time to allow significant atomic diffusion to occur. For smooth progress, a filler metal of nickel alloy was used at the interface. Optical microscopy images were used to observe the copula of the bonded layer. It was confirmed that cracks occurred near the junction in all cases. The tensile strength of the bond was measured using a universal testing machine (UTM) with WC-Co proportional test specimens.

• Journal of agricultural medicine and community health
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• v.37 no.3
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• pp.111-130
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• 2012

Objective: The purpose of this study was to identify and compare social capital measurement tools for the convenient use in public health studies. Method and result: This study examined and compared social capital tools developed individually by the World Bank, the OECD, the United States, United Kingdom, Canada, Australia, Ireland, and Korea. A comprehensive framework was constructed with six conceptual dimensions and sixteen indices. The six dimensions included Membership, Network, Trust, Information and communication, Social and civic participation, and Social cohesion and exclusion, which connoted the structural, cognitive, bonding, bridging, operative, and output elements. The indices of each tool were respectively matched to the indices of the comprehensive framework. The comprehensive tools were Integrated Questionnaire for the Measurement of Social Capital (SC-IQ) of the World Bank with 27 questions and the European Social Survey (ESS) of the OECD with 80 questions. Conclusion: The SC-IQ should be utilized in public health studies due to its simplicity yet comprehensiveness as a social capital tool. The ESS should also be considered as a comprehensive tool.

• Journal of Powder Materials
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• v.5 no.4
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• pp.303-311
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• 1998

Hard materials such as hardmetal, coated hardmetal, cermet, ceramics and diamond or c-BN sintered compact are a kind of grain-dispersed alloy with high volume of hard particles. These are used for cutting tools, wear-resistant tools, rock bits, high pressure apparatus, etc. The annual production in Japan is about 1.7 billion dollars (200 billion yen). This is greatly owed to the development in science and technology which has been accomplished by applying new concepts such as fine or uniform grain microstructure, orientation of crystal grains, functionally graded material, artificial lattice and coherent bonding in recent years. In this review, the development in recent years in Japan is briefly summarized.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.163-166
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• 2002

For the development of an all composite unmanned aerial vehicle (UAV), manufacturing consideration in design phase, works for composite parts fabrication, subassembly and final assembly are summarized. In design phase, to maximize the advantage of composite material, manufacturing processes such as cocuring, cobonding and secondary bonding are introduced. For the curing of designed parts, composite tools are designed and manufactured. Assembly jigs are designed to satisfy dimensional tolerance of the structure. Inspection criteria are established and applied to the manufacturing. Technical data about inspection items and methods are summarized as manufacturing specifications for the mass production of the UAV structure.