• Journal of the Korean Society of Safety
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• v.20 no.2 s.70
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• pp.169-174
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• 2005

Traditionally, keyboards have been one of the most frequently used input devices for information processing using computers. As most computers adopt the Microsoft Windows for their operating system however, the usage of mouse has recently increased to a great extent. Moreover, the mouse has been used as the leading input device in such areas as industrial design and computer aided design. Excessive uses of mouse may cause a severe pain and fatigue on neck and upper limb due to the intensive and repetitive use of corresponding muscles, which renders a decline in efficiency and leads to musculoskeletal disorders. The main purpose of this study is to find the best working conditions to prevent musculoskeletal disorders when using mouse in a neutral posture. Utilizing electromyogram amplitude and Borg's scale, the role change and strength imposed on the muscles were measured and analyzed with and without the forearm support concerned. Also investigated were the effects of changes in elbow forearm supporter.

• The Journal of the Korea Contents Association
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• v.10 no.1
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• pp.37-45
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• 2010

WEB or Internet has given mankind an unprecedented experience in indefinite sharing of online content by original means of digitalized information, but it comes to face an empirical issue of unreasonable informational superfluity as well as a practical issue of collapsed dot.com bubble economy in 2001. Instead, a latest networking concept called 'WEB 2.0' or 'Semantic WEB' becomes embodied as a new approach to entities such as end users and content. The concept of WEB 2.0 for creating a platform on the basis of openness and collaboration has made such a technological setting that we can effectively resolve and manage unreasonable data maintenance and interface inherent in Creative Group Thinking System (CGTS), a WEB-based computer-aided idea generation system developed in 2003. Concerning decreased usability and difficulties with data maintenance due to certain issues of CGTS as a part of WEB R&D platform, such as complex display composition and inefficient data processing system, this study seeks to simplify and streamline data structure by means of AJAX and DOM as WEB2.0-based technologies, and integrate interface structure of WEB platform to focus on end users, so that it can improve interface of conventional CGTS for the purpose of realizing end user's participation through improving usability.

• Journal of the Korean Solar Energy Society
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• v.31 no.2
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• pp.82-88
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• 2011

The artificial increase in the solar intensity incident on solar cells using lenses or mirrors can allow solar cells to generate equivalent power with a lower cost. There are two types of concentration optics for solar energy conversion. One is to use mirrors, and the other is to use Fresnel lenses. The gains that can be achieved with a Fresnel lens or a parabolic mirror are compared. The result showed the gains are comparable and the two configurations were developed competitively. In application areas of Fresnel lenses as solar concentrators, several variations of design were devised and tested. Some PV systems still use commercially available flat Fresnel lenses as concentrators. A convex linear Fresnel lens to improve the concentration ratio and the efficiency is devised and flat linear Fresnel lens in thermal energy collection is utilized. In this study, we designed and optimized flat Fresnel lens and the 'light pipe' to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the 'grooves in case' has the better efficiency than that of 'grooves out case'. Based on the ray-trace results we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

• Journal of Construction Engineering and Project Management
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• v.8 no.4
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• pp.1-24
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• 2018

In the last decade, the use of Building Information Modeling (BIM) as a new technology has been applied with traditional Computer-aided design implementations in an increasing number of architecture, engineering, and construction projects and applications. Its employment alongside construction management, can be a valuable tool in helping move these activities and projects forward in a more efficient and time-effective manner. The traditional stakeholders, i.e., Owner, A/E and the Contractor are involved in this BIM system that is used in almost every activity of construction projects, such as design, cost estimate and scheduling. This article extracts major features of the application of BIM from perspective of participating BIM components, along with the different phrases, and applies to them a logistic analysis using a fuzzy performance tree, quantifying these phrases to judge the effectiveness of the BIM techniques employed. That is to say, these fuzzy performance trees with fuzzy logic concepts can properly translate the linguistic rating into numeric expressions, and are thus employed in evaluating the influence of BIM applications as a mathematical process. The rotational fuzzy models are used to represent the membership functions of the performance values and their corresponding weights. Illustrations of the use of this fuzzy BIM performance tree are presented in the study for the uninitiated users. The results of these processes are an evaluation of BIM project performance as highly positive. The quantification of the performance ratings for the individual factors is a significant contributor to this assessment, capable of parsing vernacular language into numerical data for a more accurate and precise use in performance analysis. It is hoped that fuzzy performance trees and fuzzy set analysis can be used as a tool for the quality and risk analysis for other construction techniques in the future. Baldwin's rotational models are used to represent the membership functions of the fuzzy sets. Three scenarios are presented using fuzzy MEAN, AND and OR gates from the lowest to intermediate levels of the tree, and fuzzy SUM gate to relate the intermediate level to the top component of the tree, i.e., BIM application final performance. The use of fuzzy MEAN for lower levels and fuzzy SUM gates to reach the top level suggests the most realistic and accurate results. The methodology (fuzzy performance tree) described in this paper is appropriate to implement in today's construction industry when limited objective data is presented and it is heavily relied on experts' subjective judgment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5A
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• pp.841-848
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• 2006

There is a complex variation of stress in PSC anchorage zones and box girder diaphragms because of large concentrated load by prestress. According to the AASHTO LFRD design code, three-dimensional effects due to concentrated jacking loads shall be investigated using three-dimensional analysis procedures or may be approximated by considering separate submodels for two or more planes. In this case, the interaction of the submodels should be considered, and the model loads and results should be consistent. However, box girder diaphragms are 3-dimensional disturbed region which requires a fully three-dimensional model, and two-dimensional models are not satisfactory to model the flow of forces in diaphragms. In this study, the strengths of the prestressed box girder diaphragms are predicted using the 3-dimensional grid strut-tie model approach, which were tested to failure in University of Texas. According to the analysis results, the 3-dimensional strut-tie model approach can be possibly applied to the analysis and design of PSC box girder anchorage zones as a reasonable computer-aided approach with satisfied accuracy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.233-240
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• 2018

Radar cross section (RCS) analysis of chaff clouds is essential for the accurate detection and tracking of missile targets using radar. For this purpose, we compare the performance of two existing methods of predicting RCS of chaff clouds. One method involves summing up the RCS values of individual chaffs in a cloud, while the other method predicts the RCS values using aerodynamic models based on the probability density function. In order to compare and analyze the two techniques more precisely, the RCS of a single chaff computer-aided design model consisting of a half wavelength dipole was calculated using the commercial electromagnetic numerical analysis software, FEKO 7.0, to estimate the RCS values of chaff clouds via simulation. Thus, we verified that our method using the probability density distribution model is capable of analyzing the RCS of chaff clouds more efficiently.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.71-79
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• 2008

High voltage distribution lines in the electric railway system placed according track with communication lines and signal equipments. Case of the over head lines is occurrence the many fault because lightning, rainstorm, damage from the sea wind and so on. According this fault caused protection device to wrong operation. One line ground fault that occurs most frequently in railway high voltage distribution lines and sort of faults is line short, three line ground breaking of a wire, and so on. For this reason we need precise maintenance for prevent of the faults. The most important is early detection and fast restoration in time of fault for a safety transit. In order to develop an advanced fault location device for 22.9[kV] distribution power network in electric railway system this paper deals with new fault locating algorithm using flow technique which enable to determine the location of the fault accurately. To demonstrate its superiorities, the case studies with the algorithm and the fault analysis using PSCAD/EMTDC (Power System Computer Aided Design/Electro Magnetic Transients DC Analysis Program) were carried out with the models of direct-grounded 22.9[kV] distribution network which is supposed to be the grounding method for electric railway system in Korea.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.607-612
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• 1986

최근 테니스의 저변인구가 크게 증가함에 따라 테니스 라켓의 제작기술도 상당한 수준에 이르렀고 설계제작의 자동화에 의해서 양질의 제품이 시판되고 있다. 그러나 라켓에 볼이 임팩트될때 생기는 진동으로 야기되는 테니스 엘보우 등, 해결해야 할 문제들이 아직도 남아 있다. 이와같이 테니스 라켓의 정적인 강도 뿐만아니라 동적인 특성도 중요한 관심의 대상이 되어감에 따라 볼 컨트롤을 용이하게 한다거나, 안정타점영역(Sweet Spot)의 확장과 그립부의 진동등에 의해서 발생하는 엘보우 현상을 방지하기 위해 여러가지 연구가 수행되어 왔다. 특히, 다차원 스펙트럼해석 및 모우드 해석법에의해 그립부에 미치는 진동원의 동정과 라켓의 동적거동에 대해서 연구되었고, 라켓의 재질변경과 그립부의 구조변경에 의한 안정타점영역에 영향을 미치는 모우드 파라미터(Modal Parameter)의 추정에 관한 연구도 수행되었다. 이러한 연구들은 결국 안정타점영역을 확장시키거나 테니스 엘보우를 방지하기 위한 것으로서 이러한 목적을 달성하기위해 테니스 라켓의 진동 모우드에 관계되는 파라미터들을 찾아서 그 모우드 파라미터의 변화에 따르느 진동 모우드의 거동에 대해서 연구할 필요가 있다. 본 논문에서는 실험적인 모우드 해석법을 실제 테니스 라켓에 적용하여 모우드 파라미터들을 구한 다음 그 파라미터의 변화에 따르는 안정타점영역의 변화를 컴퓨터 시뮬레이션을 통해서 예측하였다. 또한 안정타점영역을 넓히고 라켓의 동특성을 개선시킬 수 있는 모우드 파라미터를 찾아서 테니스 라켓의 설계, 제작 단계에 정보를 제공하는 CAD(Computer Aided Design)에 좋은 자료를 얻고자 한다. 있으나 파도에 의한 영향이 가장 크므로 본 논문에서는 파도에 의한 영향만을 고려하였다. 파도는 쌍동선에 외란으로 작용하며 측정할 수 없는 양이므로 PID, LQ 제어에서는 제어모델에 포함되지 않지만 LQG 제어에서는 제어모델에 포함된다. LQG 제어의 경우 제어모델에 파도를 백색잡음으로 가정하고 제어기를 구성한 것 (LQG1)과 2차의 쉐이핑필터(shaping filter)를 사용하여 구성한 것(LQG2)으로 나누었다.져 한다.) 식도 이물에 의한, 또는 식도경술에 의한 합병증이 초래한 경우는 식도점막열상 1례 (1.8 %), 식도 천공 1례 (1.8 %) 였으며, 기도이물에 의한, 또는 기관지경술에 의한 합병증이 초래한 경우는 무기폐 2례 (11.1 %), 폐렴 3례 (16.7 %)로 나타났다.5예에서 소실되었다. 5 ) 청각심리검사 (Psychoacoustic evaluation)에서 폴립은 술전에 Grade 1∼2의 사성이 있었던 11예중 술후 10예에서 Grade 0로 되었으며 Grade 1∼2의 사성이 있었던 3예의 결절에서도 모두 Grade 0로 정상화되었다.>치를 측정한 결과 투여전과 차이가 없었다. 7) 이상의 결과로 볼때 Cis-platinum 사용으로 인한 이중독증은 신장기능이 정상일때는 충분한 hydration으로써 예방이 가능하며 동시에 금기로 알려져왔던 감음성난청이 있는 두경부악성종양환자에서도 세심한 주의하에 적절히 사용한다면 좋은 결과를 얻을 수 있을 것으로 사려된다.은 결과를 얻었기에 문헌고찰과 함께 보고하는 바이다. 1) 이관폐쇄술후 18시간에 최초로 삼출액이 확인되었으며 그 이후는 전실험군에서 삼출성중이염이 유발되다. 2

• Communications of Mathematical Education
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• v.20 no.3 s.27
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• pp.425-441
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• 2006

Entering upon 21th, the internet which bring the digital era, are changing the paradigm of education and cultivating creative and challenging person, which is the core of competitive power in knowledge-information society, is more emphasized than ever. To meet the needs of the present times, it has been concentrating its effort to improve learning-environment using e-Learning in the field of teaching. E-schoolbooks that were introduced recently by way of showing an example are representative case of this intention. Though many e-learning contents are being developed, the more speedily a society grow, the shorter the life of contents are. Moreover, the contents developed are impossible to use directly for tele-education system, so standard types adjusted for various kind of system are showing up. Among them the leading standard type is SCORM(Sharable Content Object Reference Medel) made in ADL(Advanced Distributed Learning) Corporation. The KERIS' Cyber Home Education System adopted this and is using it. So, in this study, we set the goal at designing and developing an e-learning contents and an experiment-focused mathematics that suit the KERIS' Cyber Home Education System on the basis of SCORM.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.961-966
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• 2003

A Multi-Layer Ceramic (MLC) chip type Band-Pass Filter (BPF) using BiNb$\_$0.975/Sb$\_$0.025/ $O_4$ LTCC (Low Temperature Co-fired Ceramics) and MLC processing is presented. The MLC chip BPF has the benefits of low cost and small size. The BPF consists of coupled stripline resonators and coupling capacitors. The BPF is designed to have an attenuation pole at below the passband for a receiver band of IMT-2000 handset. The computer-aided design technology is applied for analysis of the BPF frequency characteristics. The attenuation pole depends on the coupling between resonators and the coupling capacitance. An equivalent circuit and structure of MLC chip BPF are proposed. The frequency characteristics of the manufactured BPF is well acceptable for IMT-2000 application.