• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.6
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• pp.910-915
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• 2018

The precise time, which is an essential element of the Global Navigation Satellite System (GNSS), such as US GPS, GLONASS in Russia, Galileo in Europe, and Beidou in China, is an important foundation for various economic activities around the world. Communication systems, power grids, IoT, Cloud computing and financial networks operate based on the precise time not only for the operating principles, but also for the synchronization and operational efficiency between tasks. In this paper, we introduce the Atomium software for the first time in South Korea. Atomium was developed by ORB in Belgium to calculate the clock error(clock solution) with GNSS signal observation data based on PPP method. The observation data is provided by Korea Research Institute of Standards and Science(KRISS). The results of MJD57106 with Atomium software are presented.

• Korean Journal of Human Ecology
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• v.20 no.4
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• pp.849-860
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• 2011

This study explores a structural model to examine the relationship between web browsing motivation, retail strategy and purchase conversion for apparel on shopping websites. A self-administered questionnaire based on existing scales includes web browsing motivation, retail strategy, and purchase conversion intention of apparel on the shopping websites. A total of 499 usable questionnaires were obtained from consumers aging 20 to 49 who reside in metropolitan cities in Korea. For data analysis, descriptive statistics, exploratory factor analysis, confirmatory factor analysis, and structural equation models were used via SPSS 12.0 and LISREL 8.8. Findings concluded that web browsing motivations consisted of three factors: hedonic, informational, and recreational browsing for apparel. Hedonic browsing had a negative effect on purchase conversion intention, whereas informational browsing had a positive effect on the purchase conversion intention for apparel on shopping sites. Retail strategies on the website were classified into service, merchandise assortment, and price & promotion; the three elements of retail strategies mediated the relationship between web browsing motivations and purchase conversion intention for apparel. Specially, merchandise assortment had significantly direct effect on the purchase conversion intention of apparel on shopping websites. Managerial implications were discussed for fashion marketers to develop retail strategies and web content in order to convert web browsers or visitors into purchasers.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.28.3-28.3
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• 2010

위성이 궤도를 운용함에 있어서 원으로 운용되는 저궤도(LEO)에서는 대기저항(Drag)에 의한 섭동 영향이 가장 크게 미친다. 이 연구에서는 대기저항 섭동에 의해 감소되는 위성의 고도를 전기추력기를 이용하여 고도를 유지할 때 이를 해석적인 측면에 대해 살펴보고 지구 관측 위성에서 많이 쓰이는 태양 동기 궤도(SSO)에 적용하여 궤도를 유지하는 방법에 대해 알아보았다. 태양활동에 의한 대기의 밀도변화를 John kennewell의 모델을 통해 예측하여 대기저항에 의해 감소되는 고도량을 구하고 위성에서 추력(thrust)을 줄 때는 Gaussian Variation of Parameters식을 이용하여 해석적인 방법으로 궤도 장반경의 증가량을 구하였다. 위성에 추력을 줄때 이심률이 증가하게 되는 문제는 구속조건으로 이심률 값의 최대 허용치를 정하여 증가하는 것을 방지하도록 하였다. 또한 $J_2$ 섭동에 의해 가장 영향을 받는 승교점(Ascending Node)과 추력에 의해 변화할 수 있는 근지점(Perigee)을 살펴보고 궤도 유지를 위한 적절한 추력 방향을 구하였다. 각각의 궤도 요소의 변화를 살펴보고 일반적인 태양 동기 궤도 위성의 제원을 이용하여 궤도 유지에 적용하였다. 저궤도 위성의 궤도 유지에 대한 복잡한 수치적인 방법으로 궤도요소의 변화를 정확하게 구하지만 해석적인 방법으로도 위성의 궤도 유지를 위한 정보를 얻을 수 있었다. 이를 저궤도 위성의 궤도 운용과 변화 예측에 적용할 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.397-400
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• 2010

최근의 과학 실험은 그 규모나 내용에 있어서 점차 대형화되는 동시에 복잡해지고 있다. 이로 인하여 다양한 측정 장비로부터 도출된 실험 결과를 효율적으로 분석, 관리, 종합하는 도구의 필요성이 커지고 있다. 본 논문에서는 원격 측정 장치로부터 서로 다른 포맷의 실험 데이터를 자동 수집한 후 이중 정제한 데이터들만 추출하여 웹에서 시각화하는 실험 데이터 통합 관리 시스템을 제안한다. 먼저 원격 측정 장치의 데이터를 자동으로 수집하기 위해 폴링 서버를 설계하여 장치마다 폴링 에이전트를 도입하였다. 이를 통해 관리자가 각 측정 장치에 직접 접근하지 않고도 데이터를 수집할 수 있다. 폴링으로 확보한 데이터는 파싱을 통해 정제하고, 이들 데이터로 데이터베이스를 구축한다. 정제한 데이터는 시각화하여 사용자가 웹에서 쉽게 파악할 수 있다. 데이터 폴링은 TCP/IP Socket을 통해 수행하므로 보편적으로 사용하는 FTP 방식에 비해 데이터 확보 시 신뢰성을 높일 수 있으며, 폴링 여부 판단 시에는 동기식, 실제 폴링 시에는 비동기식 통신 방법을 사용하여 폴링의 효율을 높였다. 본 시스템을 활용하여 사용자의 임의적인 데이터 접근을 최소화하였고 데이터의 전송, 저장, 관리를 자동화함으로써 편의성을 높였다. 본 시스템을 활용하여 원격 실험 장치로부터 데이터를 확보할 때의 정확성과 폴링 및 파싱 속도를 실험을 통해 측정하였고, 그 결과 폴링 시 100%의 정확도와 정상 포맷의 데이터에 대해서 100%의 파싱 결과를 보임으로써 본 시스템이 원격 장치의 실험 데이터를 통합 관리할 때 적합함을 알 수 있었다. 추후 데이터의 속성에 따라 클러스터링 할 예정이며 클러스터링에 따른 시각화 서비스를 제공할 계획이다.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.11
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• pp.876-880
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• 2009

A control flow graph(CFG) is an essential data structure for program analyses based on graph theory or control-/data- flow analyses. Esterel is an imperative synchronous language and its synchronous parallelism makes it difficult to construct a CFG of an Esterel program. In this work, we present a method to construct over-approximated CFGs for Esterel. Our method is very intuitive and generated CFGs include not only exposed paths but also invisible ones. Though the CFGs may contain some inexecutable paths due to complex combinations of parallelism and exception handling, they are very useful for other program analyses.

• Journal of the Korea Safety Management & Science
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• v.14 no.4
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• pp.259-264
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• 2012

Automobile market was grown up by 1.7% at the first half of 2012 comparison with 2011 in China and this growth trend will be continued for a while. Under this market environment the China automobile companies expand the production capacity and result in heightening the intense competition for companies. This paper deals with the more efficient production line and production logistics through SPS(Synchronized Production System) with construction of MES(Manufacturing Execution System) in H automobile company in China. In plastic painting line we can simultaneously prepare the production quantity and delivery time according to assembly production plan by introducing MES. We can reduce the excess production and result in extreme reduction of inventory.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.97-102
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• 2019

The GNSS(Global Navigation Satellite System) provides important information such as Position and Navigation, Timing(PNT) to various weapon systems in the military. as a result, applications that employ satellite navigation systems are increasing. therefore, a number of studies have been conducted to deceive the weapon systems that employ GNSS. GNSS spoofing denotes the transmission of counterfeit GNSS-like signals with the intention to produce a false position and time within the victim receiver. In order to deceive the victim receiver, spoofing signal should be synchronized with GNSS signal in doppler frequency and code phase, etc. In this paper, Civilian GPS L1 C/A spoofing signals have been evaluated and analyzed by SDR receiver.

• Journal of The Korean Association For Science Education
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• v.18 no.3
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• pp.337-345
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• 1998

This study examined the influences of computer-assisted instruction(CAl) upon high school students' conceptual understanding, algorithmic problem solving ability, learning motivation, and attitudes toward chemistry instruction. CAl programs were designed to supply animated molecular motions for emphasizing the particulate dynamic nature of matter and immediate feedbacks according to students' response types at each stage of four stage problem-solving strategy(understanding, planning, solving, and reviewing). The CAl and control groups (2 classes) were selected from a girls high school in Seoul, and taught about gas law for four class hours. Data analysis indicated that the students at the CAl group scored significantly higher than those at the control group in the tests on conceptual understanding and algorithmic problem solving ability. In addition, the students at the CAl group performed significantly better in the tests on the learning motivation and attitudes toward chemistry instruction.

• Journal of The Korean Association For Science Education
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• v.25 no.5
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• pp.571-582
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• 2005

In spite of the importance of cognitive conflict in conceptual change, there has been little research on the characteristics of cognitive conflict in students enrolled at vocational high schools. The purpose of this study was to expose these students' cognitive conflict types and investigate characteristics of cognitive conflict according to the type of cognitive conflict. This paper examined how vocational students' motivational beliefs and epistemological beliefs affect the process of cognitive conflict when students are confronted with an anomalous situation related to the action and reaction concept. Results indicated that many vocational students experienced low levels of cognitive conflict and remained passive during the explanation of anomalous phenomenon or easily desisted any attempt to resolve the conflict situation because of their epistemological belief to depend on the external absolute knowledge of teachers, an extrinsic motivation to choose easier tasks, or reliance on the teachers' reputations. Therefore, Instructors need to recognize these characteristics in order to facilitate vocational students' conceptual change when presenting cognitive conflict tasks.

• Journal of The Korean Association For Science Education
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• v.20 no.4
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• pp.519-526
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• 2000

In this study, the effects of visual organization and cooperative learning in problem-solving strategy were investigated. Three classes (N=127) at a high school were assigned to SV (Strategy-Visual organization) group, SVC (Strategy-Visual organization-Cooperative learning) group, and control group. After instructions, students' multiple-choice problem-solving ability, strategy performing ability, anxiety about chemistry learning, perception of involvement, and motivation to learning science were examined. Although multiple-choice problem-solving ability was not different significantly, there was a significant main effect in strategy performing ability. The scores of the SV and SVC groups were significantly higher than those of the control group, especially in the subcategories of problem understanding and recalling related principles. In the tests of perception of involvement and motivation to learning science, the scores of the SV and SVC groups were also significantly higher than those of the control group. However, problem-solving strategy using visual organization could not alleviate anxiety about chemistry learning.