• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.73-81
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• 2011

As high speed digital systems continue to use components with faster edge rate and clock speeds, transmission of the digital information, it can bring about many troubles. The increasing requirement for controlled impedance PCBs becomes both a critical success factor and a design challenge to implement a system. Especially, the noise sources in high frequency digital systems include the noise in power supply, ground and packaging, and they destroy the fidelity of signals. Therefore PCB design with impendence matching is needed to improve fidelity of signal in H/W. In this paper, we have developed an impedance control and analysis tool for multi-layer PCB design, and simulates the tracks controlled impedance with the test coupon. So, it can save the design time and support the economical PCB design.

• The Journal of Society for e-Business Studies
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• v.10 no.4
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• pp.53-81
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• 2005

Current DRM system has limitation in protection of user's privacy Therefore, many troubles are expected in service providing if it comes into the ubiquitous times of context-aware environment. HKUST Proposed a watermark-based web service DRM system. However, the relevant study does not consider ubiquitous environment and cannot provide service that considered a context. And privacy protection of a user is impossible. On the other hand, Netherlands Phillips laboratory indicated a privacy problem of a DRM system and they proposed an alternative method about this. However, in relevant study, a Sniffing/Replay attack is possible if communicated authentication information are exposed between a user and device. We designed web services adaptable privacy-aware DRM architecture which supplements these disadvantages. Our architecture can secure user authentication mechanism for sniffing/Replay attack and keep anonymity and protect privacy Therefore , we can implement the privacy-aware considered web service DRM system in Context-Aware environment.

• Journal of Korean Society of Archives and Records Management
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• v.20 no.1
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• pp.207-212
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• 2020

This paper introduces the process in which the Center for Freedom of Information, founded for the public's right to know by disseminating public information, was created . Building archives with scarce resources and capacities has resulted in a number of troubles and frustrations, and the need for reorientation. However, through the contributions of many people empathizing with the unique needs and meanings of citizen-led archives, difficulties were overcome, and archives were built. This paper summarizes the specific difficulties and capabilities required in this process, especially the knowledge and assistance needed in the field of records management. Although much research is necessary, the archives serve as an example of remembering and reconstructing the past when the 1997 Crisis Archives had shaken all the foundations of people's lives, and a tool to guide decision-making.

• Journal of the Korean Home Economics Association
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• v.33 no.3
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• pp.225-242
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• 1995

This study was undertaken to review the relationship between middle-school students' food-behavior and their health conditions/school performances. For this purpose, 495 male and female middle-school students were sampled form seven middle schools located in Seoul for a questionnaire survey. The surveyed data were analysed with simple frequency, percentage, t-test, chi-square test, dispersion analysis, Pearson's correlation and hierarchical multiple-regression analysis which make use of the SPSS/PC+ package system. The results of survey can be summarized as follows; Most of students had three meals a day regularly, but some female students used to skip breakfast or supper. The amount of a mael was adequate. Their main night-smacks were fruits. The problem perceived by students was unbalanced meal ; Female students took more snack than that of male students. They usually took a snack a day. All students tended to take delicious snacks. The most favorate smack of students was fruits. Most students did not suffer any serious diseases, but some had one or more respiratory diseases. Female students had some or other physical troubles in their eyes, mouth, digesting organs, muscle/bone, skin and had fatigue. Female students had mental problems of depression, uneasiness and hostility. The average I.Q. of students was 117.4, and those who had higher I.Q. got much higher scores. The regularity and amount of meal and intake of animal food were all positively related with the growth of height and weight. And the taller, the higher I.Q. they had. Those students who took meals three times regularly and adequately, who had no coffee and snack and who took balanced meals were healthier in both physical and mental terms. In particular, those who had adequate amount of breakfast regularly were not only healthier but also had higher I.Q. and school performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.481-484
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• 2002

News service provide professional knowledge which can't be gained from any other internet service and the only way to keep pace with professional group. To get this advantage, many country provide news service and three major korean news server connected with foreign news server provide many articles to korea. A lot of institutes - company, research centers and universities - forward articles to home and abroad. In spite of this important effect, The user of news service and technical supports grow smaller. And now It is necessary for a nation to support and operate by non-profitable business. Especially, partially adapted security weaken entire system safety and can't satisfy service provider of various necessary condition. In this paper, we will mention troubles in authentication and suggest safety authentication method which must be supported by established news service.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1634-1642
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• 2014

Mobile RFID system, that consists of the existing RFID reader mounted on the mobile devices such as smartphones, is able to provide the users a variety of services and convenience. But security of mobile RFID system is too weak like the existing RFID system. In this paper, the mobile RFID mutual authentication protocol with high level of security is proposed to overcome the troubles such as cryptographic protocols in the existing RFID system responding with the same value in every authentication procedure and the exposure in the exchange of messages. The proposed protocol exchanges messages unexposed by using the random numbers generated in the mutual authentication between the tag and the reader and making numbers coded with the symmetric key. Besides, the protocol uses the mutual authentication utilizing OTP by considering the characteristics of the reader embedded in mobile devices in the mutual authentication process between the reader and the server. Because changed message in every authentication, which produces safe from spoofing attacks and replay attacks, etc.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.535-537
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• 2013

Recently, the quality of the incident of school violence is getting worse and the frequency of its occurrence is gradually increasing. One of the biggest reasons that violence in schools does not reduce is because the attitude that they mean to hide damage from the violence, thus the improvement of such conditions enables school violence to decrease in the short-term effect. This study designed an intelligent reporting platform to prevent additional violence and victim's suicide, by related agencies and parents reporting the circumstance of school violence real-time, as both victims and attackers register real-time troubles anonymously, at any time, anywhere, then are provided 1:1 counseling and customized services, and all contents of the counseling are accumulated in the intelligent reporting platform.

• Resources Recycling
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• v.18 no.3
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• pp.62-68
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• 2009

Continuous operation for 24h was carried out to establish the optimum condition at the magnesium fused salt electrolysis using a self made 150 ampere mono-polar type cell. An electrolyte composition of $MgCl_2$ 25%, NaCl 55%, $CaCl_2$ 19%, $CaF_2$ 1% was electrolyzed with applied voltage 7V, cathode current density $0.7-0.75A/cm^2$, electrode distance 6cm at $720{\sim}740^{\circ}C$ for 24 hours. Changes of applied current, composition of the electrolyte, current efficiency were investigated. Through the experiments, there were not any operating troubles with the self-made electrolytic cell. Purity of the electrolyzed magnesium metal was above 99%, and 89% of current efficiency was achieved. Some basic data for scale-up of the magnesium electrolysis equipment which would be necessary for commercialization were obtained.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.445-451
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• 2016

It is very important to obtain non-agglomerated nano particle state for practical application of nano technology. In order to improve the functionality of products using nano particles, more precise control of particle size distribution is required in their synthesis process. However, synthesized nano particles are agglomerated easily due to physical and chemical reasons, and it then veils unique properties of the nano particles and causes some troubles in their practical application. In this study, a separation method for nano particles from suspension by using the droplets as the separation space was proposed. Using the suspension of 0.002 wt. % with $TiO_2$ powder, the particle size distribution of nano particles in the recollected suspension was measured. From the results, it was confirmed that it is possible to separate and to recollect the nano particles monodispersed by using the suggested method.

• Spatial Information Research
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• v.12 no.2
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• pp.127-135
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• 2004

The operational availability of multispectral high-resolution satellite imagery, opens up new possibilities for updating forest map. Compared with information acquired by traditional methods (Panchromatic Aerial Photo), these data of for a number of advantages. In this study used 1m spatial resolution and 4 multispectral band, which are capability to update forest map of kind of tree. From the result of this study, First, the visual analysis of the colour composites of the multispectral data made it possible to distinguish some species(conifer, broad-leaved, un-stocked, arable land). Second, forest map and orthorectiffd satellite imagery are not match in the boundary of forest, therefore work have some troubles in the modification of forest map. Third, the distinguish from age-class, girth-class and density are much need experience and skillful about sample such as aerial photo.