• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1233-1240
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• 2004

Recently the need for cooperative control among robots is increasing in a variety of industrial robot applications. Such a control framework enhances the efficiency of the real robotic assembly environment along with extending the robot application. In this paper, an ethernet-based cooperative control framework was proposed. The cooperative control of robots can multiply the handling capacity of robot system, and make it possible to implement jigless cooperation, due to realization of trajectory-synchronized movement between a master robot and slave robots. Coordinate transformation was used to relate among robots in a common coordinate. An optimized ethernet protocol of HiNet was developed to maximize the speed of communication and to minimize the error of synchronous movement. The proposed algorithm and optimization of network protocol was tested in several class of robots.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.674-677
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• 2006

Orthogonal frequency division multiple access (OFDMA) has emerged as one of the core multiple access schemes in 4G to mitigate the problems of frequency selectivity and inter-symbol interferences. In OFDMA, cooperative transmission can be adopted in transmission between each user and base station. Cooperative transmission can provide better channel environments and additional transmitter diversity. In this paper, we formulate a user and subcarrier assignment problem in OFDMA system with user cooperation and propose an efficient scheme to solve it.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.253-270
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• 2015

Two major simultaneous attack strategies have been introduced, as one of cooperative attack of multiple missiles. One strategy is an undesignated time attack, in which the missiles communicate among themselves to synchronize the arrival times by reducing the mutual differences of times-to-go of multiple missiles during the homing. The other is a designated time attack, in which a common impact time is commanded to all members in advance, and thereafter each missile tries to home on the target on time independently. For this individual homing, Impact-Time-Control Guidance (ITCG) law is required. After introducing cooperative proportional navigation (CPN) for the first strategy, this article presents a new closed-form ITCG guidance solution for the second strategy. It is based on the linear formulation, employing base trajectories driven by PNG with various navigation constants. Nonlinear simulation of several engagement situations demonstrates the performance and feasibility of the proposed ITCG law.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.1
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• pp.17-23
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• 2013

This study analyzed the efficiencies of Korean fisheries cooperative's 97 operation offices in the capital and surrounding area. We used the DEA model for checking the technical and scale efficiencies in the financial business of them. We divided the business into two parts, the productivity (efficiency for increasing deposit and loan) and profitability (efficiency for increasing the profit and reducing the risk from the loan). The results show that the additional profitability increase is very difficult because most of the offices have full technical efficiency for profitability. But additional analysis based on Slack-based Measure (SBM) DEA model shows that Kyung-Gi region can increase the profitability. SBM model analysis also gives us the possibility that customized policy can apply to each offices considering each factors affecting the productivity and profitability.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.05a
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• pp.244-245
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• 2004

• Proceedings of the Korea Society of Design Studies Conference
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• 2005.10a
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• pp.206-207
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• 2005

• Journal of the Society of Naval Architects of Korea
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• v.40 no.1
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• pp.47-54
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• 2003

The majority of small/medium sized shipbuilders in Korea is poor in capital and then, should be restructured as an efficient production system with low investment. Due to considering this situation, the cooperative work system is proposed, in this study, as more effective production system for small/medium sized shipbuilder The cooperative work system Is the production system that many small/medium sized shipbuilders in a group jointly share the common facilities except minimum equipments and have managerial cooperation such as joint purchase of raw materials. The efficiency of cooperative work system is proved from economic and technical point of view with the case study of FRP shipbuilders of Sapjin industrial complex located at Mokpo area.

• Design & Manufacturing
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• v.12 no.1
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• pp.7-12
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• 2018

The present status of the mold industry, including the size of the mold industry in Korea, its position in the global market, the production of the mold industry, import and export, and recent trends in the mold industry were examined. The survey was implemented for the trends fo dies and molds industry in 2017 by answers on business environment for Korean Mold Industry Cooperative Union members. The sharp decline in plastic mold exports in 2015 led to a decline in overall exports. China and Japan account for a very large share of mold exporting countries, but exports to emerging markets such as India, Mexico and Vietnam contributed to the overall increase in mold exports. China, Japan, India, the United States and Mexico were named as exporting countries with more than US $ 200 million, and Vietnam showed similar tendency as a major exporter. A survey conducted by the Korea Mold Industry Cooperative Association showed that the decrease in production and exports was predicted. In order to overcome the difficulties of the mold industry, the need for research on the linkage of the mold industry and technology to the wave of the fourth industrial revolution has increased.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.238-245
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• 2018

The skin experiences constant physical stimuli, such as stretching. Exposure to excessive physical stimuli stresses the skin and can accelerate aging. In this study, we applied a method that allowed human fibroblasts and keratinocytes to be perfused with media to form 3D skin equivalents that were then uniaxially 10%-stretched for 12 h per day (at either 0.01 or 0.05 Hz) for up to 7 days to form wrinkled skin-on-a-chip (WSOC). There was more wrinkling seen in skin equivalents under 0.01 Hz uniaxial stretching than there was for non-stretched skin equivalents. At 0.05 Hz, the stratum corneum almost disappeared from the skin equivalents, indicating that stretching was harmful for the epidermis. At both frequencies, the production of collagen and related proteins in the skin equivalents, such as fibronectin 10 and keratin, decreased more than those in the non-stretched equivalents, indicating that the dermis also suffered from the repeated tensile stress. These results suggest that WSOCs can be used to examine skin aging and as an in vitro tool to evaluate the efficacy of anti-wrinkle cosmetics and medicines.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.45-52
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• 2016

The purpose of this study was to investigate the meaning of conflict experience in cooperative learning activities of pre-service early childhood teachers. The subjects were 85 pre-service early childhood teachers in W university. The data were collected through unstructured interviews and journal writings of the participants. The study results were as follow. First, pre-service early childhood teacher's conflict experiences in cooperative activity are team meeting, fair participation and evaluation, and conflict of the personal relations. Second, pre-service early childhood teacher's conflict resolution experiences in cooperative activity are autonomy of the team meeting time, reflective thinking, sentimental support, recognition of others, and solving problems by the time spending together. Third, the meanings of conflict experience in cooperative activity are formation of felt responsibility, self-growth through consideration of others, reciprocity, and recognition of the meaning of cooperation.