• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2412-2418
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• 2009

As an astonishing progress of FTTH infrastructure, the new technologies have been widely studied to use the tantalizing benefits of high bandwidth in fiber optic cable. In this paper, a new VONU is presented to perform all necessary optical functions. It can converts digital and analog CATV signals and satellite-based signal transmitted via one fiber optic cable to electrical signals (electric lights). However, most previous VONU systems have the problems such as interference between difference services, signal distortion, and noise increasing rate. These problems cause the quality deterioration in broadcasting. Therefore, we suggest the new VONU system to solve all problems listed above. In addition, we show that how our system performs well by measuring the real data with implemented system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.314-324
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• 2004

Recently, high-speed internet subscribers have grown continuously, and reached up to 10 millions. But existing network management that is responsible only for user access is confronted with many difficulties, since user access network(xDSL, Cable, B-WILL, and so on) has diversified and value added wired/wireless contents service has developed. In this paper propose the Agent based Inter Networking platform as object-oriented hierarchical system that can provide various service such as access QoS(Quality of Service), customized application service and security service according to user on demand. This system has divided into two parts(user agent and agent management system ＆ local and central management systems). Management system periodically receive status information such as bandwidth, download speed, delay, current service, and so on, and process them, then build a policy based on processed information. According to personal user profile that is generated by this policy, the customized service can be provided for users. And This system adopt the object-oriented modeling in case that system migration and integration, and implement a system that is robust and stable for security through hierarchical server system.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.593-601
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• 2001

This paper presents an efficient system for power system education using 3-D computer graphics animation in the PC environment. Several power system phenomena are simulated using Real-Time Digital Simulator. Results are transmitted through on-line communication line to PC for graphic animation, and simulated in the 3-D graphics animation. It can immediately reflect user control input and re-simulated this result. The proposed method was tested on both the sub-synchronous resonance phenomena and multi-bus system. It is expected that the proposed method would be helpful for the operator training as well as power system education.

• Journal of the Korean Magnetics Society
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• v.22 no.6
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• pp.200-203
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• 2012

In this study, we have investigated that the operation frequency dependences of the output properties of the orthogonal fluxgate sensor which was fabricated with a ferrite core. An orthogonal fluxgate sensor should be operated in as high as possible frequency to enhance its sensitivity in the case of small sized sensor, because sensitivity of the sensor is proportional to cross section area, winding number and operation frequency. In this study, we investigated the correspondence of the frequency dependence of output and the reactance (inductance and capacitance) of pickup coil and cable. Experimental results represented that we could obtain maximum output (= sensitivity) at optimal frequency which is near LC resonance frequency of the pickup coil and cable.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.23-34
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• 2013

This study would verify the validity of two transmission technology, 'Clear QAM' and '8VSB'. 'Clear QAM' and '8VSB', the transmisson technology, have been suggested as the concrete alternatives in the situation that half of subscriber of multi channel tv service have been still out of benefit from digital convert. In this study, we have shown that the introduction of 'Clear QAM' and '8VSB' should ease economical burdens and information minority group without extra set-top box. But there is another concern that it should negatively affect on the contents industry by a devaluation of the multi channel tv service or by an infringement of copyright. In these reasons, it is still difficult to solve the related concern, though the government have to set up the politic goal for the related industry as well digital convert. This study suggested that Korea Communication Commission consider above-mentioned technology temporarily, and reconsider 'Clear QAM' around the completion of the digital convert project.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.217-221
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• 2009

The use of the carbon nanotube (CNT) is superior to the general powder state materials in their thermal and chemical properties. Because its ratio of diameter to length (aspect ratio) is very large, it is known to be a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of the semiconductive shield materials used in power cables can acquire excellent properties by the use of a small amount of CNTs. Therefore, we fabricated specimens using a solution mixing method. We investigated the thermal properties of the CNT, such as its storage modulus, loss modulus, and its tan delta using a dynamic mechanical analysis 2980. We found that a high thermal resistance level is demonstrated by using a small amount of CNTs. We also investigated the chemical properties of the CNT, such as the oxidation reaction by using Fourier transform infrared spectroscopy (FT-IR) made by Travel IR. In the case of the FT-IR tests, we searched for some degree of oxidation by detecting the carboxyl group (C=O). The results confirm a tendency for a high cross-linking density in a new network in which the CNTs situated between the carbon black constituent molecules show a bond using similar constructive properties.

• Journal of Internet of Things and Convergence
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• v.8 no.1
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• pp.17-22
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• 2022

This paper is a study on the self-powered wireless bus information and disaster information system based on Internet of Things (IoT). The existing bus information system supplies power and communication by cable, which causes a problem of increased installation cost and limited installation site due to cable burial. To solve this problem, a self-powered wireless bus information and disaster information system was proposed. The proposed system provides bus arrival information. Furthermore, in the event of a disaster such as a natural disaster, it can also reduce confusion and damage by notifying the disaster information through the system's speaker. In this study, a self-powered system using a solar module was proposed. As data are transmitted and received through wireless WiFi or LTE, the installation cost can be reduced and the problem of installation location restrictions can be solved.

• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.109-116
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• 2016

A flexible concrete mattress (FCM) is a structural system for protecting submarine power or communication cables under various load types. To evaluate its of protection performance, a numerical analysis of an FCM under an anchor collision was performed. The explicit dynamics of the finite element analysis program ANSYS were used for the collision analysis. The influences of the steel reinforcement modeling and collision angle of the anchor on the collision behavior of the FCM were estimated. The FCM damage was evaluated based on the results of the numerical analysis considering the numerical modeling and collision environment.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1355-1359
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• 2004

The two way subscriber transmission systems have tendency to spread its carrier frequency bandwidth or information bit rate and average bit error rate according to popularization of high speed information through the digital communication system, transmission medium and the Internet. This fact is an important incentive to realize new systems. These two way subscriber transmission systems usually use same cable or same carrier frequency bandwidth for up stream channel and down stream channel. In the systems, the disturbances of noise, crosstalk or fading affect the characteristics. Specifically, these disturbances cause the decrease of information bit rate and degradation of transmission quality. This paper proposes the improved method of their degradations using the particular feature of two way subscriber transmission systems and it makes clear proposed method is effective by theoretically and some numerical examples.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.211-219
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• 2004

Due to rapid increases in Internet users, it becomes essential to provide well-established web services and monitor web server's load for the sake of reliable web server management. The existing web server load monitoring has been based on such cable methods as RPC, RMI, CORBA and etc. But it has the limitation in bringing information both anywhere and anytime over the Internet. This thesis is aimed to realize real-time wireless web server monitoring system based on Wireless Application Protocol (WAP). As any user can log on wirelessly to the Internet at any time through wireless terminals like PDA, the realization will make possible instant and real-time web server monitoring.