• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.33-39
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• 2010

In order to operate the power system satisfactory for both system operators and customers, it is important to limit the harmonic currents to the allowable levels which injected into the system from the distorting installations. In this regard, the principles for the allocation of emission limits on individual customer were introduced in the technical report of IEC61000-3-6. According to these general principles, the emission limits are dependent on the agreed power of the customer, the power of the harmonic-generating equipment, and the system characteristics. The considerations in this report are very comprehensive and the process introduced is practical enough to implement as it is. However, there is a fact not appropriately dealing in the report that could be a very tickle but has a huge impact on determining the emission limit. This is the effect of non-harmonic load currents. More precisely, these are from the equipments which do not emit any harmonic or may emit harmonics but this specific order under the consideration by themselves if the source power is sinusoidal. The load currents originated from these equipments have an effect of active filter against the specific order of harmonic therefore, these should be dealt as a significant factoron the process of determining the emission limits for individual customer.

• Journal of Nutrition and Health
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• v.36 no.9
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• pp.960-965
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• 2003

For the purpose of developing 'internet nutritional education program', this study analyzed the actual states of internet nutritional information of middle/high school students. Survey questionnaires were distributed from October 21, 2002 to October 26,2002 to a total of 564 students at three junior high schools and five senior high schools located in Seoul. The total number of questionnaires collected and used in our study was 479, which is 84.9% of the total questionnaires distributed. According to the survey results, we found significant difference in the nutritional information source between middle and high school students (p < 0.05) , and two groups responded that effective nutrition information material is 'electronic materials'. Most of the respondents connected with internet more than 1 times per day, but a large number of students were not experienced in using nutrition information of the internet. All groups were using nutrition information of the internet for homework, and satisfaction level of using nutrition information of the internet were an average. Effective methods for acquiring nutrition information of internet were 'educational game' for middle school students and 'bulletin board (Q & A)'for high school students. Moreover the factor analysis for internet nutritional information program's characteristics showed that 'instructing plans','contents of study & technical support','availability'and'interaction'were important considerations for developing internet nutritional information program. We found out through our analysis that was a strong need for a more practical and effective internet nutritional education program for middle and high school students.

• Korean Management Science Review
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• v.17 no.3
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• pp.119-129
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• 2000

Design of web site must include community considerations alongside technical design aspects. The main purposes of this study are to identify the community criteria for evaluating web site and to examine how business web sites include the community factors. To identify the evaluation criteria, the author reviewed recent literatures and made a table showing a summary result(see Table 1). appendix shows a sample form NASDAQ(n=82) and KOSDAQ(n=59) which were evaluated. Using the evaluation from with 189 items(Table 3), all sites were visited and review between August 28, 2000 and September 6, 2000. The auther’s evaluations were done from the perspective of community building in business sector. Table 4, summary data on the results of the study, shows that the level of application of the community concept is very low. Among the listed 18 items, only a few items are utilized at more than 50% level. Less than 10% items are Member Profile, Group Segmentation, Backstory, Forum, Chat, Fact-to-face Meeting, and Collaborative Design. the unbalanced utilization due to the lack of community concept in businesses are found. Korea firms are superior to NASDAQ firms in terms of Bulletin Board and FAQ; But Korean firms are inferior and remain at very low level in terms of Member Login, Education Materials, Backstory, Forum, and Integrating Off-line Activities which are core factors of community building.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.441-443
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• 2015

디지털 홀로그래픽 TV 시스템을 구현하려면 홀로그래픽 정보 획득 장치가 필요한데, 해상도 한계 때문에 홀로그램의 프린지 패턴을 상용 촬상 소자로는 직접 기록할 수 없다. 이를 극복하는 방법으로는 컬러 영상과 거리영상 정보를 얻은 후에 압축을 거쳐 수신 디스플레이단에 전송하고 이 정보로부터 3차원 모델을 형성한 후에 컴퓨터 생성 홀로그램을 생성하고 이를 회절소자를 이용하여 디스플레이하는 방법이 현재로서는 현실적인 방법이 될 것이다. 홀로그래픽 디스플레이에서는 회절소자인 공간광변조기 성능의 한계 때문에 기존 2DTV와 같은 수준의 디스플레이 구현은 매우 어렵다. 기존 공간광변조기는 픽셀피치가 커서 시야각이 매우 좁으나, 픽셀 크기를 작게 하는 동시에 공간광변조기 면적을 크게 하기에는 기술적인 어려움이 많다. 본 논문에서는 홀로그래픽 TV를 구현하는데 있어서 기술적으로 극복하고 고려해야 할 주요 요소에 대하여 분석한다.

• Journal of the Korean Society for information Management
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• v.23 no.2
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• pp.113-127
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• 2006

This paper addresses issues related to the design of an interface supporting fine grained interaction with documents, focusing on a particular type of scholarly documents, journal articles. In order to make a usable interface we need to understand user behaviors as well as technologies that present new possibilities of enhancing user experience. This paper reviews studies along three dimensions : user information behavior in searching/using documents, new conceptual/technical models for electronic documents, and interaction mechanisms. Putting together the understanding of users and enabling technologies, requirements and considerations in developing systems with granular interactions are discussed in the conclusion.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.1949-1954
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• 2010

The gyroscopes have been used as a suitable inertial instrument for the navigation guidance and attitude controls. The accuracy as very sensitive sensor is limited by the lock-in region(dead band) due to the frequency coupling between two counter-propagating waves at low rotation rates. This frequency coupling gives no phase difference, and an angular increment is not detected. This problem can be overcome by mechanically dithering the gyroscope. This paper presents the design method of mechanical dither by the theoretical considerations and the verification of the theoretical equations through FEM(Finite Element Method) applications. As a result, the maximum prediction error of resonant frequency and peak dither rate was under 5 percent. The theoretical equations for the mechanical performances of dither can be said to be feasible.

• Convergence Security Journal
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• v.17 no.3
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• pp.31-40
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• 2017

UAV (Unmanned Aerial Vehicle) is increasingly used in diverse fields such as disaster, distributi on, and logistics, but it is pointed out that the inadequacy of related laws and invasion of privacy is an obstacle to industrial growth. The regulatory framework for UAV convergence services is pr oposed based on the regulatory framework. From the technical point of view, regulation on archite ctural design, from the market point of view, concurrent operation of services in a limited area, a l egal evaluation based on post-evaluation rather than a pre-regulation under the legislation of visua l information protection law and a social consensus will contribute to the early settlement of UAV -based convergence services.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.85-88
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• 2009

Recently "DMB Video-Associated Stereoscopic Data Services" standard has been published by TTA. The standard enables DMB broadcasters to provide 3D or stereoscopic interactive data services based on MPEG-4 BIFS (Binary Format for Scenes). The purpose is to entice viewers to utilize DMB interactive data services more often by providing realistic and protrusive image objects overlaid on top of the main video in the background. This paper provides the background, technical analysis, and in-depth considerations for the standard. Also the results of standard verification are provided including the results of interoperability test with the existing terrestrial DMB receivers.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.495-507
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• 1998

This article intends to review what problems the terms in calculus have and how those problems are caused. For this purpose We make examinations on the considerations in the analysis of mathematical terminology, which includes the problems of general and technical terms, the meaning and the boundary of words, their consistency, the name and meaning, concept and their concept images, translations and qwerty effects. And in chapter 3, We analyse the textbook which are currently used, through which I was able to find out that the terms in calculus have some problems, In other words, the key terms such as "differentiable", "differential coefficient", "differential" have their roots in the term "differential" but the term "derived function" is very distinct from other terms and thus obstructs the consistency of terms. And the central term "differential" is being used without clear definition. In particular, the fact that "differential", when used in its arbitrary definition, has the image of "splitting minutely" can be an obstacle to understanding the exact concepts of calculus. In chapter 4, We make a review on the history of calculus and the term "differential" currently used in modern mathematics so that I can identify the origin of the problem connected with the usage of the term "differential". We should recognize the specified problems and its causes and keep their instructional implications in mind. Furthermore, following researches and discussions should be made on whether the terminology system of calculus should be reestablished and how the reestablishment should be made.e terminology system of calculus should be reestablished and how the reestablishment should be made.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.118-121
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• 2008

Bimodal tram is a transit with no-step floor for wheel-chaired persons, with docking to the station precisely and moving on schedule like train. Because of the automatic traveling of bimodal tram to search and follow the magnet embedded in roadway, bimodal tram should be careful about rainfall, snow and wind like a car driving on roadway in respect to natural disasters. Though response procedures in emergency are different according to the passengers' boarding, emergency mobilization is needed if any emergency situation happens. Emergency mobilization is the act of preparing for major catastrophic events, which may affect public transportation systems or their service areas, by assembling and organizing resources, including people, equipment, facilities, communications systems, expert technical support, and public information systems and protocols. Mobilization is the process that ensures that the right people will deploy appropriate resources at the correct time. Effective mobilization requires a partnership of local and state agencies. Public transportation operators and systems play vital roles in response to and recovery from emergencies and other unexpected catastrophic events. These systems, and their capabilities to mobilize resources, are profoundly affected by the decisions and directives of others during these activities. In this study, we focused on the emergency management for bimodal tram and reviewed the considerations about infrastructures under natural disasters, especially heavy rainfall.