• 대한산업공학회지
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• 제16권1호
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• pp.67-81
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• 1990

Effectiveness of physical exercise in reducing work-related musculoskeletal stress was investigated. This was compared to the stress alleviation accomplished by using ergonomically designed work station. Tasks chosen for the study were data entry and file maintenance on the video display terminal (VDT). Three different measures, namely root-mean-square (RMS) values of electromyogram (EMG), subjective rating and task performance were used for the evaluation. Electromyograms were recorded from the neck, the left and right trapezius muscles in the shoulder region, and L2/L3 region of the back. Subjects rated discomfort levels for the same parts of their body. Task performance was measured by recording typing speed and errors. Each of the five subjects was tested for two days (8 hours/day) in two different work stations. These were the ergonomically designed adjustable work station and the fixed work station of traditional design with no adjustable features. Assigned physical exercises were performed for four minutes, every two hours during the breaks, by the subjects while working in the fixed work station. It was concluded that the physical exercise could be helpful in reducing musculoskeletal stress as effectively as the ergonomic design of the VDT work station.

• 인터넷정보학회논문지
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• 제21권6호
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• pp.33-39
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• 2020

The paper is to build recommendation systems leveraging Deep Learning and Big Data platform, Spark to predict item ratings of the Amazon e-commerce site. Recommendation system in e-commerce has become extremely popular in recent years and it is very important for both customers and sellers in daily life. It means providing the users with products and services they are interested in. Therecommendation systems need users' previous shopping activities and digital footprints to make best recommendation purpose for next item shopping. We developed the recommendation models in Amazon AWS Cloud services to predict the users' ratings for the items with the massive data set of Amazon customer reviews. We also present Big Data architecture to afford the large scale data set for storing and computation. And, we adopted deep learning for machine learning community as it is known that it has higher accuracy for the massive data set. In the end, a comparative conclusion in terms of the accuracy as well as the performance is illustrated with the Deep Learning architecture with Spark ML and the traditional Big Data architecture, Spark ML alone.

• 한국전산구조공학회논문집
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• 제23권1호
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• pp.61-71
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• 2010

기 수행된 1, 2종 교량에 관한 정밀안전진단 등의 많은 사례를 분석해 보면, 실제로 많은 경우 외관상태가 교량의 대표등급 결정에 지배적인 요인이 되는 것을 볼 수 있다. 본 연구는 기 시행된 점검 및 진단 자료를 학습사례집합으로 인공지능 분야의 귀납적 학습법을 활용하여 철근 콘크리트 교량 바닥판의 상태평가를 지배하는 상태속성들의 교량등급에 대한 계층적 영향도와 구조적 연관성을 분석하였다. 이는 세부적으로 목표속성은 평가등급으로, 평가속성은 1방향균열, 2방향균열, 백태, 박락 및 층분리, 재료분리 등 7가지로 구성하고, 엔트로피 분석을 통해 주요 속성의 정보량, 정보기대값 및 정보 이득을 산정하고 범주별 상태 등급 분포를 분석하였다. 이를 위해 본 논문은 먼저 6개 교량에 대한 안전진단보고서를 토대로 상태등급 평가 과정에서 각 속성이 미치는 간접적 영향을 개관하고 정보공학적 분석의 동기를 부여하였다. 아울러 본 연구는 정보 변별력에 대한 순서로 평가를 지배하는 주 속성 및 조건별 하위 속성 연관성을 의사결정트리 형태로 나타내어 계층적 영향 및 속성간의 구조적 연관성을 보임으로써 손상에 대한 이해도를 높이고 차후 상태평가를 위한 합리적 접근을 지원할 수 있도록 하였다.

• 아동학회지
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• 제26권5호
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• pp.89-104
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• 2005

Ecological predictors of imaginative playfulness were researched to test relationships among preschoolers' individual characteristics, socioeconomic status, their visual media use, and their imaginative playfulness. Data were collected from 202 primary caregivers and head teachers in childcare centers in Michigan, U. S. A. Use of visual media was coded by the program categorization of Anderson et al. (2001) and the Television and Movie Violence Rating Scale (Huesmann et al. 2003). Imaginative playfulness was rated by the adapted Playfulness Scale (Barnett 1990). Results of hierarchical regression showed that child characteristics of age and gender predictors contributed to their imaginative playfulness. On the other hand, children's visual media use and socioeconomic status of their families did not predict their imaginative playfulness.

• 한국지진공학회논문집
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• 제18권1호
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• pp.19-28
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• 2014

The seismic evaluation of electric power facilities in the switchyard of nuclear power plants is currently insufficient. In order to evaluate the seismic performance of lightning arrester subjected to four types of earthquake (near- and far-fault earthquakes, NEHRP Site Class A&B and D earthquakes), seismic fragility analysis using maximum likelihood estimation is performed considering various damage states. The comparison of the seismic fragility curves for three main parts of lightning arrester that are the busing, anchor and steel frame, reveals that the failure of lightning arrester is governed by the bushing damage mode such as porcelain cracking.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권7호
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• pp.349-356
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• 1999

Wide operating range and speed control is needed for wind power generating and a Doubly Fed Induction Generator(DFIG) has good adaptivity for that purpose. This paper deals with the speed and power control using the Grid connected DFIG in the super-synchronous speed regions, by controlling frequency and voltage fed to the rotor. Power flow of the DFIG and steady-state algebraic equations of the equivalent circuit are analyzed. For the speed control analysis, torque simulation is performed whereby the different slip between operating motor driving frequency and synchronous frequency of M-G system applied. To keep the output rating of the generator, the exciting frequency and voltage attenuation are applied.

• 패션비즈니스
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• 제19권6호
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• pp.127-138
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• 2015

Due to the virtual nature of online businesses, online apparel stores need to enhance the consumer experience by utilizing store design attributes to provide their customers relevant and sufficient information. Since online apparel stores mainly communicate with their customers virtually and digitally, it is important to understand how consumers perceive and react to different design attributes commonly found on apparel stores' online websites. The purpose of this paper is to examine the importance of design attributes commonly found on online apparel stores' websites using three different importance measurements. The design attributes examined in this study include enlarged pictures, product detail pictures, product reviews by other buyers, coordinating items, and size measurement charts. The three different measurements used in this study include two direct measures and one indirect measure using conjoint analysis. Across the three different measures, both the men and women indicated that enlarged pictures represent the most important design attribute when they purchase clothes online followed by size measurement charts and they considered the availability of coordinating items the least important design attribute.

• 대한전기학회논문지
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• 제43권2호
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• pp.251-258
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• 1994

To apply the Power MOSFET to the high powerd circuits, the parallel operation of the Power MOSFET must be considered because of their low power rating. This means, in practical applications, design methods for the parallel operations are required. However, it is very difficult to investigate the problem of parallel operations by directly changing the internal parameters of the MOSFET. Thus, in this paper, the effects of internal parameters for the parallel operation are investigated using SPICE program which is often used and known that the program is very reliable. The investigation results show that while the gate resistance and gate capacitances are the parameters which affect to the dynamic switching operations, the drain and source resistances are the parameters which affect to the steady-state current unbalances. Through this investigation, the design methods for the parallel operation of the MOSFET are suggested, which, in turn, contributes to the practical use of Power MOSFETs.

• 환경위생공학
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• 제15권2호
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• pp.85-94
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• 2000

The comparative evaluation is the most effective method for site selection because the selection of waste treatment facility is to determine the optimum site out of limited candidate sites. This study adopted the ordinal scale evaluation, one of methods of comparative evaluation. The ordinal scale evaluation aims to determine the investigating items referring to the character of sites, to determine the importance factors for investigating items, and to determine the optimum site according to the quantitative evaluation. This study has focussed on reflecting the opinion of residents to the maximum extent with a weight on social and economic aspects, considering the state of confrontation against each other between the autonomous government organization and local residents, which is being emerged as a social issue relating to the evaluation rating on each item of site selection of an optimum site. Therefore, rational, and clear validity investigations and proper reduction of both time and expenses in site selection as well through this a study.

• Journal of Power Electronics
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• 제10권3호
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• pp.245-250
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• 2010

Input-series-output-parallel (ISOP) converters consisting of multiple modular DC/DC converters can enable low voltage rating switches to be used under high voltage input applications. This paper presents a digital control strategy, which can achieve equal sharing of input voltage for a modular ISOP system consisting of two-transistor forward DC/DC converters by forcing the input voltages of neighboring modules to be equal. The proposed scheme is analyzed using small signals analysis based on the state space average method. The performance of the proposed control strategy is verified with an experimental prototype of an ISOP converter made up of three two-switch forward converters.