• Journal of Korean Society for Geospatial Information Science
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• v.24 no.3
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• pp.29-38
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• 2016

As publicizing of electromagnetic devices such as smart_phone and drone etc. which are relate with geomagnetic direction, and recognition about the importance to space weather effect and their hazards rises up recently, it is required heavily that the study on the effective measurement of geomagnetic declination and geomagnetic field effects of space weather. The purpose of this study is that the investigation of the feasibility of the absolute geomagnetic measurement in a place, where man-made geomagnetic contamination is low or negligible, with replacing the azimuth marks used for the absolute geomagnetic declination measurement with unified control points(UCP) which established at suburb. Further to this, have first derived the correlation of daily variations and disturbance level between the published indices($K_P$ and $K_K$) and geomagnetic element calculated from geomagnetic data of Cheongyang observatory located at the middle stage in Korea and is a member of INTERMAGNET. In addition, have carried out that the absolute measurement for the geomagnetic declination at three places near unified control point and one place with wide open field in Korea. The world magnetic models(WMMs) are selected as the criteria for comparison on the feasibility of geomagnetic declination investigation near unified control points. We compared deviations of declination from absolute measurement with that obtained from WMMs, also those from WMMs inter-comparison. The result through examination and analysis show that the feasibility of the absolute geomagnetic declination measurement with replacing the azimuth marks with UCP which established at suburb is possible.

• Economic and Environmental Geology
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• v.48 no.1
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• pp.51-63
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• 2015

I produced a secular variation model of geomagnetic field by using the magnetic component data from four geomagnetic observatories located in Northeast Asia during the years between 1997 and 2011. The Earth's magnetic field varies with time and location due to the dynamics of fluid outer core and the magnetic observatories on the surface measure in time series. To adequately represent the magnetic field or secular variations of the Earth, a spatio-temporal model is required. In making a global model, satellite observations as well as limited observatory data are necessary to cover the regions and time intervals. However, you need a considerable work and time to process a huge amount of the dataset with complicated signal separation procedures. When you update the model, the same amount of chores is demanded. Besides, the global model might be affected by the measurement errors of each observatory that are biased and the processing errors in satellite data so that the accuracy of the model would be degraded. In this study, as considered these problems, I introduced a localized method in modeling secular variation of the Earth's magnetic field over Northeast Asia region. Secular variation data from three Japanese observatories and one Chinese observatory that are all in the INTERMAGNET are implemented in the model valid between 1997 to 2011 with the interval of 6 months. With the resulting model, I compared with the global model called CHAOS-4, which includes the main, secular variation and secular acceleration models between 1997 to 2013 by using the three satellites' databases and INTERMAGNET observatory data. Also, the geomagnetic 'jerk' which is known as a sudden change in the time derivatives of the main field of the Earth, was discussed from the localized secular acceleration coefficients derived from spline models.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.4
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• pp.331-338
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• 1999

This paper describes the variations of geomagnetic field by analyzing the geomagnetic observation data, which spanned the period from 1918 through 1944 and the global geomagnetic model in Korea. Geomagnetic data observed at Incheon in the period of 1918~1944 and global geomagnetic model (IGRF-95) were obtained from the World Geomagnetic Data Center. In this study, the variations of geomagnetic declination is estimated as $1^\circ{50'}$ from 1918 to 2000 and the variation rate is given as the nearest 1'20"/yr. The total variation of inclination is about 38' for 82 years and the variation rate is estimated as the nearest 27"/yr."/yr.;/yr.

• The Journal of the Korea Contents Association
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• v.22 no.1
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• pp.148-161
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• 2022

Korea's design developed closely related to economic growth and plays a key role in material growth, wealth growth, and consumption promotion today. Of course, it is true that Korea's design level has grown significantly, but it has not reached a trend-leading level. Behind this, it is thought that one of the reasons behind this is that most design companies are biased towards trend research and benchmarking from a supplier perspective, resulting in the creation of design sculptures. If you look at the examples that lead the world's design trends, you can see that their subjective thinking from the author's point of view accounts for a significant portion of design sculpture creation. Through an in-depth interview with designers and artists at both extremes of the spectrum of thought, I want to look at examples of self-expression design development and get implications for suggesting conceptual models of self-expression design sculpture. Through this, a conceptual model was proposed, which is organized into a five-step design creation process in which balanced thinking is achieved by combining the thinking system and process according to the writer's point of view with the majority of design creation dominated by supplier perspective.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.299-307
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• 2021

As the COVID-19 pandemic spread around the world, more and more universities are conducting real-time distance video lectures using ZOOM, Webex, and MS Teams. This study attempts to identify the factors influencing learner satisfaction of real-time distance video lectures. Based on the existing research, it was composed of five elements (system factor, content quality, interaction, self-direction, and learning motivation) as learner satisfaction elements of real-time distance video lectures. As a result of analyzing the structural equation model of 160 effective questionnaires by conducting a survey of college students in the metropolitan and Chungcheong areas, it was found that three factors (interaction, self-direction, and learning motivation) influence learner satisfaction. Real-time distance video lectures are expected to continue to expand in the future. Therefore, universities should continuously increase learner satisfaction through the development and evaluation of real-time distance video lecture satisfaction models.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.204-216
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• 2021

This study empirically analyzed factors affecting consumers' intention to use metaverse by applying the extended technology acceptance model. In other words, the factors affecting the intention to use the metaverse were set as content quality, perceived enjoyment, social influence, self-efficacy, and investigated from the perspective of the expanded technology acceptance model. For this end, a survey was conducted on 296 university students in Seoul, and the collected data from 267 students were analyzed using SPSS 25.0 and AMOS 23.0. As a result, it was found that perceived usefulness and perceived ease of use, which are the antecedent variables of the extended technology acceptance model, affect the intention to use the metaverse, and perceived ease of use has an effect on perceived usefulness. Content quality and perceived enjoyment had an effect on perceived usefulness, perceived ease of use and intention to use metaverse. Social influence was found to affect perceived usefulness and intention to use metaverse. Also, self-efficacy was found to affect perceived ease of use and intention to use metaverse.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.53-63
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• 2011

An SNS(Social Network Service) enables people to form a social network on online as in the real world. With the rising popularity of the service, side effects of SNSs were issued. Therefore we propose and implement a policy-based privacy protection module and access control policy language for ensuring the right of control of personal information and sharing data among SNSs. The policy language for protecting privacy is based on an attribute-based access control model which grants an access to personal information based on a user's attributes. The policy language and the privacy protection module proposed to give the right of control of personal information to the owner, they can be adopted to other application domains in which privacy protection is needed as well as secure sharing data among SNSs.

• Journal of The Korean Association of Information Education
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• v.14 no.2
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• pp.273-283
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• 2010

Emergent process or behaviour can be seen in many places, from any multicellular biological organism to traffic patterns, cities or organizational phenomena in computer simulations. Similarly, the concept of 'Green IT' refers to the way complex systems and patterns arise inevitably among groups due to environmental concerns in real world. Green IT has good possibility to evolve as very chaotic system, in which the number of interactions between components increases geometrically with the number of components, thus potentially allowing for many new types of behaviour to emerge. However, when Green IT system regards as a complexity one, there exits some attractors to derive and control the system. In this context, this paper presents a new model based on type-2 fuzzy logic system to identify and assess the attractors of Green IT system which correspond to Reach-Richness matrix of Green IT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.10-23
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• 2001

It is difficult to satisfy the QoS(Quality of Service) guarantee which is required by real-time application services only with the Best-Effort(BE) service adopted in the current Internet. Therefore, worldwide research is being made on the method of QoS provisioning. Among them, the QoS guarantee mechanism using the Diffserv(Differentiated Service) was discussed in this paper. First we analyzed how the DiffServ performance was affected by traffic models. For this, we performed the research for the random, bursts, and self-similar traffic modeling method. We then designed and implemented an OPNET simulator, and performed the simulation 7d performance evaluation for diverse input parameters. Based on the results of performance evaluation, it was confirmed that QoS guarantee is possible for the EF(Expedited Forwarding) class with the DiffServ function under every environments considered and the service separation between EF and BE(Best Effort) classes is also possible. We also analyzed the performance variation and dynamic behavior of DiffServ mechanism based on the resource allocation between E? and BE classes in WFQ(Weighted Fair Queueing).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.230-230
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• 2007

전력선 통신(Power Line Communication)은 최근 전력선을 이용한 통신기술의 발달과 더불어 세계적으로 관심도가 높아지고 연구 개발 및 자본 투자가 활발히 진행되고 있으며, 안정적인 네트워크를 구성하기 위해서는 고주파 전력선 통신 신호를 차단하는 블로킹 필터가 반드시 적용되어야 한다. 전력선 통신용 블로킹 필터는 광대역의 주파수 특성과 높은 신호감쇄 특성 및 대전류 특성이 요구되며, 이러한 특성을 구현하기 위해서는 블로킹 필터의 핵심부품인 자심재료의 고투자율 및 대전류화가 이루어져야 한다. 따라서 본 연구에서는 우수한 전 자기적 특성이 균일하게 유지되고, 전력선에 흐르는 대전류에 의한 자심재료의 포화가 발생하지 않도륵 새로운 자심 재료를 설계하여, 전력선 통신을 적용한 홈 네트워크 구축의 핵심 부품인 광대역 블로킹 필터를 개발하고자 하였다. 2350과 0.3 T의 투자율과 포화자속 밀도를 갖는 EI 형상의 자심재료를 해석모델로 설정하고 다중 에어 갭의 위치에 따른 전류와 자속밀도 변화를 유한요소 해석법으로 분석한 결과 자심재료의 대전류 특성에 지배적인 영향을 미치는 에어 캡의 삽입 위치를 알 수 있었고, 새로운 해석 모델인 I 형상의 로드(ROD) 코어에 대해 수치해석을 수행하여, 100A의 통전 전류에서도 자기적으로 포화되지 않고 인덕턴스의 정밀 제어가 가능하고, 특성의 신뢰성과 대전류에 대한 안정성을 증가시킬 수 있는 인덕터를 설계하였다. 또한 수동소자를 이용한 LC 공진회로를 기본 구성으로 하고, 주파수 대역, 신호 감쇄율과 대전류 특성, 상용화를 고려하여 블로킹 필터 회로를 설계하였으며, 유한요소해석법을 적용한 전자장 모의해석을 통하여 최소의 크기를 갖는 I 형상의 자심재료에 $6{\Phi}$의 에나멜 동선을 6.5턴, 6턴 권선하여 2.5, $2.15\;{\mu}H$의 인덕턴스를 갖는 직렬 인덕터를 구현하였고 블로킹 필터를 구성하였다. 주파수에 따른 신호감쇄 특성을 5 Hz~1 MHz의 주파수 범위에서 측정한 결과 약 490 kHz~450 kHz의 주파수 대역에서 -70dB의 신호감쇄 특성을 나타냈다. 본 연구를 통해 개발된 100A급 광대역 블로킹 필터가 적용되어 상용화 될 수 있을 것으로 판단되며, 또한 모뎀 통신 주파수 대역에서 -70dB 이상의 높은 감쇄 특성을 갖기 때문에 신호차단 특성이 보다 우수할 것으로 사료된다.