• 한국국방경영분석학회지
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• 제24권1호
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• pp.176-188
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• 1998

In this paper, it is identified that the optimal level of each performance measures (service and inventory level) is not sensitive to an uncertain environment under JIT Kanban system designed by Moeeni. Moreover, it is proposed that the optimal design method considering multiple performance characteristics is the optimal level decision method according to the relative importance differences of each performance when there exist multiple performance characteristics. The result from the simulation analysis shows that the number of Kanban for stage 3 (final process) and stage 2 is increased at the service level. It is found that the expected loss is minimal when the cycle time decreases and the container size increases. However, the stage 1 is not affected by the number and cycle time of Kanban. It is thus important to consider carefully the cycle time and the container size of the Kanban to satisfy the demand in right time. In case of inventory level, the working inventory level decreases when the container size is decreased and the working inventory level also decreases slightly when the cycle time of the Kankban is increased in stage 1 and 2.

• 한국전기전자재료학회논문지
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• 제21권11호
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• pp.987-994
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• 2008

The optimal structure of the Tonpilz transducer was designed. First, the FE model of the transducer was constructed, that included all the details of the transducer which used practical environment. The validity of the FE model was verified through the impedance analysis of the transducer. Second, the resonance frequency, the sound pressure, the bandwidth, and the impulsive shock pressure of the transducer in relation to its structural variables were analyzed. Third, the design method of $2^n$ experiments was employed to reduce the number of analysis cases, and through statistical multiple regression analysis of the results, the functional forms of the transducer performances that could consider the cross-coupled effects of the structural variables were derived. Based on the all results, the optimal geometry of the Tonpilz transducer that had the highest sound pressure level at the desired working environment was determined through the optimization with the SQP-PD method of a target function composed of the transducer performance. Furthermore, for the convenience of a user, the automatic process program making the optimal structure of the acoustic transducer automatically at a given target and a desired working environment was made. The developed method can reflect all the cross-coupled effects of multiple structural variables, and can be extended to the design of general acoustic transducers.

• 해양환경안전학회지
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• 제24권3호
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• pp.360-366
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• 2018

In shipyards hull forming is performed by the line heating method using a gas torch and by cold treatment using a roll-press. However, this forming process has some issues, such as difficulties in controlling and accurately estimating the amount of the heat input, as well as a harsh working environment due to exposure to loud noises and air pollution. The induction heating method, which is introduced in this paper, exhibits good control and allows for the estimation of precise heat input. Also, workers can carry out the induction heating in a comfortable working environment. In this research, the induction heating simulation, which consists of electro-magnetic, heat transfer and thermal elasto-plastic analysis, was developed and modified through induction heating experiments. Finally, the effective heating coil was designed for the automatic hull forming system based on the results of induction heating simulation. For the purposes of a future study, if an algorithm to obtain optimal working conditions is developed, automatic systems for hull forming can then be constructed.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1063-1070
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• 2008

The performance of an acoustic transducer is determined by the effects of many design variables, and mostly the influences of these design variables are not linearly independent of each other. To achieve the optimal performance of an acoustic transducer, we must consider the cross-coupled effects of the design variables. In this study, the variation of the performances of underwater acoustic transducer in relation to its structural variables was analyzed. In addition, the new optimal design scheme of an acoustic transducer that could reflect not only individual but also all the cross-coupled effects of multiple structural variables, and could determine the detailed geometry of the transducer with great efficiency and rapidity was developed. The validation of the new optimal design scheme was verified by applying the optimal structure design of a flextensional transducer which are the most common use for high power underwater acoustic transducer. With the finite element analysis(FEA), we analyzed the variation of the resonance frequency, sound pressure, and working depth of a flextensional transducer in relation to its design variables. Through statistical multiple regression analysis of the results, we derived functional forms of the resonance frequency, sound pressure, and working depth in terms of the design variables. By applying the constrained optimization technique, Sequential Quadratic Programming Method of Phenichny and Danilin(SQP-PD), to the derived function, we designed and verified the optimal structure of the Class IV flextensional transducer that could provide the highest sound pressure level and highest working depth at a given operation frequency of 1 kHz.

• The Journal of Asian Finance, Economics and Business
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• 제7권6호
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• pp.475-484
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• 2020

This study investigates determinants of talent retention in textile and garment companies located in Vietnam's Binh Duong province to propose feasible actions for their sustainable development in the current context of competition on the labor market. This study uses self-completed questionnaires to collect data which are then analysed with statistical methods including scale reliability, exploratory factor analysis, and multiple linear regression. Specifically, results from an official survey of 129 people who are regarded as talents in related companies show that there are ten determinants, ranked in descending order of their importance, including: working environment; training and promotion opportunities; salary and benefits; personal loyalty; relationship with colleagues; nature of work; organizational recognition; type of ownership; relationship with superiors; and working experience. Moreover, it is also found that foreign companies are better in retaining their talents than private domestic ones. These findings suggest that, depending on their available resources, organizations need to focus on some of these factors to improve their talent retention; among them, it is critical to provide creative space or create conductive working environment by providing talents with proper tools and equipment for them to feel excited with their work and get things done in an optimal, efficient and effective manner.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권5호
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• pp.568-576
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• 2017

With an increase in the usage of LNG, there is a heightened interest about its safety aspects regarding the explosion of LNG carrier tank. The need for a cryogenic explosion-proof camera has increased. The camera has to work in cryogenic environment (below $-160^{\circ}C$) in LNG carrier. This study conducted design and heat transfer analysis of cryogenic camera to secure working time in limitation of heat source. The design with gap width of double pane windows was conducted based on simple vertical cavity model to insulate from cryogenic environment. The optimal gap width was 12.5 mm. For effective analysis considering convection within the camera, equivalent thermal conductivity method was adopted with ABAQUS. The working time of the camera predicted was over 10 h at warm-start condition. In cold-start condition, it required about 5 h of pre-warming time to work. The results of analysis were compared with the ones of the actual cryogenic test.

• 시스템엔지니어링학술지
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• 제7권2호
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• pp.1-5
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• 2011

The purpose of the Environment Design (ED) for Main Control Room (MCR) of Nuclear Power Plant (NPP) is to provide and create an optimal working space to be free from physical, physiological and mental stress as well as environmental discomfort, based on the previous environment design experiences and to recommend the best ED including the color, the lighting and the interior design. Environment Design consists of three main areas: Human factor engineering design, Interior design with color design, and Lighting design. These design areas have been interactively cooperated in a way that each design specialist would share the objectives and concepts of the Environment Design for MCR. The specialists for Human Factors Engineering design had a corporative role in such a way to provide the guidelines for MCR design suitability of Interior and Lighting design considering the Human System Interface (HSI) safety concerns. This paper describes fruitful efforts to create the best fit for MCR ED among several design proposals with the design recommendations, impacts, and contributions to NPP environment.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.140-141
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• 2016

Dynamic nature and diverse requirements on construction sites make the automation technology harder to be employed actively. In this study, we analyzed optimal type of automation system and importance of core technologies for developing efficient construction automation system on 11 construction operations. As a result, it showed that man-machine cooperation system may be the most suitable for most operations, while autonomous robot will be best suited in hard working environment such as maintenance of exterior wall. In elemental technology, ease and accuracy of control and operation showed higher priority than others regardless of automation system type. These findings will provide useful information for developing the construction automation system.

• 전자공학회논문지
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• 제53권10호
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• pp.51-57
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• 2016

본 논문에서는 에너지관리의 효율성 향상을 위하여 데이터 추론기법과 클라우드 호스팅 기법을 활용한 최적의 에너지 관리시스템을 제안하였다. 에너지 절약 및 효율적인 관리 기법이 에너지 생산 및 공급을 줄이기 위해서 매우 유용하다는 점에 대한 관심이 부각되고 있다. 에너지 관리시스템은 컴퓨터를 사용하여 합리적인 에너지 이용과 함께 쾌적하고 기능적인 업무 환경을 효율적으로 유지 보전하기 위한 제어 관리시스템을 의미한다. 제안 시스템은 에너지관리를 위해 다양한 설비를 제어하고, 에너지 소비 환경의 변화로부터 추론을 위한 데이터를 획득하며, 에너지를 사용하는 환경의 변화에 최적으로 적응함으로써 효율적인 에너지 관리가 가능하도록 구현되었다. 구현된 시스템의 성능을 평가하기 위해서 대상 설비에 대한 추론엔진이 작동하는 서버에서 월간 전력사용량을 고려한 실험을 실시하였고, 그 결과 우수한 성능을 보임을 확인하였다.

• 교육시설 논문지
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• 제21권4호
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• pp.21-30
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• 2014

In general, teachers' perceptions on the physical environment of elementary school are related on the quality of education and school life. But, we don't have study what teachers think of their enviroment of school. This study analyzed elementary school teachers' satisfaction with overall physical environment and their assessment of spaces with specific functions in order to understand teachers' perception of the physical environment of elementary schools. A survey questionnaire was administered to 982 homeroom teachers working at 67 elementary schools located in Seoul and Busan. Teachers' satisfaction with physical environment of school and their assessment were analyzed comparatively according to the teachers' personal attributes and school conditions. 1) Most of the surveyed teachers were satisfied with overall physical environment of the school, and assessed high the substantiality of functional spaces indoor and outdoor. By sub-factor, however, their satisfaction with work environment was lower than that with education and living environment. 2) The teachers perceived that the optimal number of classes was 30~36, and this is probably because they were relatively accustomed to large scale schools. 3) As might be expected, negative assessments were more frequent among teachers working at a large-scale school, an old school, or a school with small outdoor spaces. The results of this study show that, though partially different according to region, gender, teaching experience and school condition, teachers' satisfaction with school environment was relatively high. This suggests that elementary school teachers perceive their current school environment positively. Because they are accustomed to traditional education methods that have been maintained.