• 경영과학
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• 제18권1호
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• pp.79-88
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• 2001

We often feel the necessity to communicate with members involved in a project to remote discuss business activities, needs for the fast file transfer, and check the existence of members to talk with. There are some commercial applications in these problems. However, in addition to those existing functions, this study focuses especially on adding couple of functions such as automatic responding function, in which a sender of a message automatically knows if a receiver checks the message. Its application is that a project leader sends an important message and later on can check at his desk the fact that who have checked their messages. The prototype application, build in this study, will check the correctness of every sub-function, and then the interface of inter-sub-functions, finally the integrity of the entire system, so that important information will not be lost among members of a project in the real world situation.

• 기술사
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• 제43권1호
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• pp.26-31
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• 2010

The changes of climate and earth environment caused by Global Warming has seriously occurred recently. For instance, the water in the Chad Lake in Africa has continuously disappeared and Tuvalu in the South Pacific is facing a serious natural disaster with that the entire country is sinking under the sea. These natural disasters become a serious risk threatening the existence of the human-race. Therefore, we needs a fundamental measure to prevent Global Warming. That is a natural phenomenon that makes the earth warmer by 6 types a greenhouse gas including $CO_2So$ we look for an answer from the 'Green Growth' movement.

• 아동학회지
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• 제25권4호
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• pp.71-92
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• 2004

The purpose of this ethnographic study was to observe and understand interactions of toddlers and teachers in context. Specific questions were "What are the motives and features of the interactions between toddlers and teacher?" Subjects were twenty 2-year-old daycare children and their teachers. Methods covered 11 weeks of interviews and participatory observation. The major findings were that the interactions between toddlers and teachers was mainly initiated by toddlers and consist of physiological and emotional needs, conflict mediation and participation in play. As toddler get to the age of self-recognition but still need adult's assistance, the co-existence of dependence and independence was evident. Children used a variety of verbal and non-verbal signals with both positive and non-positive overtons.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.379-382
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• 2006

We are investigating the effect of particle on electrowetting, and this paper reports the experimental results obtained until now. The experiment was performed for different particle sizes, electrolyte concentration, and AC frequencies. The problem is quite complicated by various factors, such as the existence of surfactant in suspension and sedimentation of particles. We could not draw a concrete conclusion on the effect of particles, and it needs further investigations. We also report interesting phenomena observed during the experiment. It includes the droplet generation at the edge of a droplet, pseudo-bistability of electrowetting, flow generation inside a droplet, and the chain formation of particles inside a droplet.

• 한국가구학회지
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• 제26권4호
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• pp.467-473
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• 2015

Natural dyeing is considered to be an alternative to chemical staining in terms of harmful VOC-free and environmentally-friendly ingredient. This study was concerned with an evaluation of color performance of naturally dyed- and painted veneer for cylindrical laminated veneer lumber etc. according to the used condition in terms of existence of light and heat in drying. From the results, the color changes by the color of dyed veneer and the type of paint are likely to be affected by fading condition of light or heat. In the future, long-term outdoor exposure test needs to be additionally followed in order to evaluate durable usability of colored veneers.

• 경영과학
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• 제26권1호
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• pp.113-126
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• 2009

By the newly emerging network access technology, we face the new heterogeneous network environment. Focusing on the co-existence of multiple access network technology and the complex service needs of users, the wireless service operators should present the stable service quality for every user. For this, the service operators should build the new operation framework which combine the pre-established network and newly adopted one. Our problem is finding the optimal heterogeneous network operation framework. We suggest market-based marginal cost function for evaluating the relative value of resource of each network and develop the whole new heterogeneous network operation framework. To test the applicability of developed operation framework, we build large-scale JAVA simulator. By this development, we can easily test the new network environment in practical engineering field.

• 전기학회논문지P
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• 제57권1호
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• pp.36-40
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• 2008

Most of the low-voltage feeder are designed with approximately balanced and connected at the three phase four wire systems. However, Most of the power distribution systems' load which is composed of single or three phase are unbalanced by generating load unbalance. Unbalanced current will draw a highly unbalanced voltage. The power factor of an induction motor at rated operation is between 25 and 90%, depending on the size and speed of the motor. However, many induction motors operate below the nominal rating, resulting in poor power factor. This condition needs power factor improvement. Addition of power capacitor at the motor terminal may draw to stress due to voltage unbalance. This paper presents operation characteristics on steady states of a three-phase induction motor under unbalanced voltages with power capacitor. The existence of voltage unbalance have an effect on stress of power capacitor.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2007년도 춘계학술대회
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• pp.73-80
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• 2007

Recently, the strategy of the age of limitless competition for existence of manufacturing company appears for the enhancement of productivity through the automatic system, the reduction for the cost for standardization and the decision making process for the information system. Especially the critical success factors in manufacturing company can be summarized for the establishment of production visibility through the production management, material & work-in-process management, the establish of the flexible manufacturing system for the changed order priority and the establish of the quality system for improvement of product and process quality. The existing production management systems supply only simple information about production results on real time, can delay quick decision making. And it can prevent acquiring the information about various customer needs and the communication problems with other systems. In this paper, it will show MES system, a solution for the problems of existing production management systems. And through a case study of D company, it will reveal improvement effect on shipment error using MES system and economic analysis for MES itself.

• 전기학회논문지
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• 제60권2호
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• pp.330-337
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• 2011

This paper presents a new fuzzy speed controller based on a fuzzy angular acceleration observer to realize a robust speed control of permanent magnet synchronous motors(PMSM). The proposed speed controller needs the information of the angular acceleration, thus the first-order fuzzy acceleration observer is designed. The LMI existence condition is given for the proposed fuzzy speed controller, and the gain matrices of the controller are calculated. It is verified that the augmented control system consisting of the fuzzy speed controller and the fuzzy acceleration observer is mathematically stable. To validate the effectiveness of the proposed acceleration observer-based fuzzy speed controller, the simulation and experimental results are shown under motor parameter variations. It is definitely proven that the proposed control scheme can precisely track the speed of a permanent magnet synchronous motor.

• 한국안전학회지
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• 제11권3호
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• pp.168-176
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• 1996

Statistical analysis of occupational accidents plays an important role in establishing measures against accidents and for evaluating safety performance in work places. This research work, numerous numbers of research work have been conducted, which attemped to verify the existence of !he concept of "accident proneness" Also researches have been developed in the fields of systems safety analysis and risk analysis to analyze the characteristics of occupational accidents. This paper presents a brief historical review of these research activities with particular emphasis on the statistical analysis of occupational accidents. Based on this review, further development needs in relation to the statistical research on the occupational accidents in the near future are discussed.discussed.