• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.671-674
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• 2012

Recently, depending on the development of smart devices, a variable services have been offered to meet user's convenience. Due to these advance, the needs of users are extremely being diversified and more specific. In that situation, the needs for the N-Screen system has been varied and gradually evolved. An existing N-Screen system that use the way of video streaming upload its multimedia contents to their own cloud server so that might take a long play-reaction time and the number of user is limited by the server's performance. Because of the web based protocol adopted by existing N-Screen system, there are many different problems like high delay, overhead and something caused by simplex data communications. Therefore, to solve the problems above, this study proposes an application based on HTML5. This application supports Video tag and Progressive download via HTML5 so that improves the play-reaction time for multimedia contents. This system can also get rid of the chronic problems such as an access limitation for lots of users as per video streaming encoding. Also, through web sockets, this study proposes a system that has lower delay than the existing system and communicates in full duplex to be able to link dynamically.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2003년도 추계학술대회 논문요약집
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• pp.115-115
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• 2003

최근 회전기계에 대한 세계적인 기술추세를 볼 때 해를 거듭할수록 더욱 정밀해지고 고속화에 대한 요구가 한층 증대되고 있으며 이러한 측면에서 여러 분야에 우수한 장점을 지니고 있는 능동적 자기베어링의 회전축계 활용에 대한 연구가 활발히 진행되고 있다. 특히 프랑스를 중심으로 한 미국, 일본 등이 이에 대한 연구를 활발하게 수행하여 고속 공작기계 스핀들을 비롯한 고진공 펌프 및 각종 터어빈, 압축기 등에 실용화시키는 단계에 있다. 그러나 국내 관련기술에 대한 연구는 연구소, 학계를 중심으로 실험실적인 기초연구로서 부분적으로 수행하는 단계에 있으며 관련분야 활용을 위한 본격적인 연구는 수행되지 못하고 있는 실정이고 이를 실용화시키기 위한 일환으로 능동적 자기 베어링의 회전 축계를 구성하고 있는 요소기술 중 하나인 전력 증폭기의 개발이 이뤄져야 할 필요성이 있는데 본 논문에서는 네트웍 기반 전력 증폭기 개발을 시도하였다. 전력 증폭기는 크게 리니어 앰프와 스위칭 앰프로 구분된다. 리니어 앰프의 경우 회로가 간단하고 노이즈가 비교적 작다는 장점이 있지만 전력손실 및 발열이 크기 때문에 에너지 측면에서 저 효율이라는 점과 따로 방열판을 부착해야 한다는 단점을 가지고 있고, 스위칭 앰프의 경우 전력손실이 작은 반면, 회로가 비교적 복잡하고 노이즈의 발생 가능성이 높다는 단점이 있다. 본 논문에선 위 두 가지 방식을 혼합한 혼합형 전력 증폭기로 설계하였다. 또한 기존에 전력증폭기의 경우 상위 주제어기로부터 제어량을 아날로그 신호로 통신하기 때문에 발생할 수 있는 EMI 노이즈신호에 대한 대책을 세워야 하는데 본 연구를 통해 개발된 전력증폭기는 따로 보조제어기(TMS320LF2406A)를 두어 상위 주제어기에 전력증폭기의 상태값을 궤환할 수 있도록 명령 신호체계를 전체 시스템의 샘플링 시간을 고려하여 비교적 전송 속도가 빠른 CAN(Controller Area Network)으로 구축하여 주제어기와 전력 증폭기간에 양방향 통신이 가능하도록 하였다. 이로써 전력증폭기의 상태정보를 알 수 있다. 따라서 본 논문에서는 칩 설계기술의 발전으로 가격대 성능비가 우수한 DSP(TMS320LF2406A)를 이용하여 과거의 아날로그 방식의 명령신호체계를 디지털 신호체계로 바꿈으로써 네트웍을 통해 전력증폭기의 상태진단 가능성을 검증한다.

• The Journal of the Korea institute of electronic communication sciences
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• 제15권5호
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• pp.931-938
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• 2020

Recently, with the expansion of the use of cross media, the public is not just watching the broadcast, but is also consuming various information about actor, stories, products, etc. that appears during the broadcast. However, the devices used for viewing and the devices used for searching are different, which is inconveniences, and due to the differences between the point in time when the desired information is provided through the search, the public has difficulty in obtaining detailed information of the target product after encountering product placement advertisement. In addition, it is difficult for advertisers to confirm the effect of product placement advertising through the reaction of viewers who have encountered product placement advertising. In this paper, we intend to propose an interactive streaming platform that supports the instant retrieval of product information to users by including product placement advertisement information in broadcasting. Through this, viewers can quickly receive detailed information of products on the screen by giving an event when a product of interest comes out while watching the broadcast, and advertisers can check the effectiveness of product placement advertisements by receiving interactive responses from viewers.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제17권9호
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• pp.2063-2072
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• 2013

Smart Grid is the next-generation intelligent power grid that maximizes energy efficiency with the convergence of IT technologies and the existing power grid. It enables consumers to check power rates in real time for active power consumption. It also enables suppliers to measure their expected power generation load, which stabilizes the operation of the power system. However, there are high possibility that various kinds of security threats such as data exposure, data theft, and privacy invasion may occur in interactive communication with intelligent devices. Therefore, to establish a secure environment for responding to such security threat with the smart grid, the key management technique, which is the core of the development of a security mechanism, is required. Using a hash chain, this paper suggests a group key management mechanism that is efficiently applicable to the smart grid environment with its hierarchical structure, and analyzes the security and efficiency of the suggested group key management framework.

• Journal of KIISE:Information Networking
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• 제31권6호
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• pp.620-632
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• 2004

IP is not suitable for mobile nodes by network-based routing because mobile nodes are dynamically change their network attachment point. Mobile-IP is an IETF standard providing continuous access to the Internet for mobile nodes, but it has the triangle routing problem. Also it has a performance degradation problem by massive packet loss during layer 3 handoff of mobile nodes. Especially, two IETF multicast support schemes for Mobile-IP do not guarantee the quality of realtime multimedia services because they have several problems such as long routing path, packet duplication(hi-directional tunneling) and massive packet loss(remote subscription). In this paper, we propose a lossless remote subscription scheme that guarantees the quality of realtime multimedia services over Mobile-IP. From the result of simulation, we verified that the proposed scheme in this paper can reduce the delay time of remote subscription by the effect of the low latency handoff scheme that is extended to apply to the multicast group management and it requires only 0.58% buffer spaces of the previously proposed lossless remote subscription scheme.

• Journal of Satellite, Information and Communications
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• 제12권4호
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• pp.11-17
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• 2017

In this paper, we propose the authoring tools engine supported a 4 dimension display contents which serve display of high quality (UHD*250) curved using 4 dimension engine, which is a innovation technology by authoring tools of management software supported 4 dimension editing environment on curved flexible display. The important technology is as follows, the first, the authoring tools of 4 dimension viedo wall for a flexible high quality display(UHD*256) using multiscreen synchornization, the second implemented a bidirection interaction technology of UI/UX interface, which is established by 360 degree recognition sensor for digital signage, the 4 dimension viedowall flexible display with curve, the third, implemented the authoring tool software for various dimension electronic books first in the world.

• Journal of Advanced Navigation Technology
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• 제21권1호
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• pp.113-118
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• 2017

As interest in mobile devices and networks has increased recently, voice over internet protocol (VoIP) service, which is a technology for transmitting voice data using an existing internet protocol (IP) network, has rapidly spread, Cheap voice call service has become possible. As the digital broadcasting service becomes popular, hybrid fiber coaxial (HFC) network technology, which uses broadband cable network through fusion of broadcasting and communication, utilizes existing communication system and network equipment to provide various new services such as interactive broadcasting service. Therefore, if UGS-AD is applied to VoCM and RTPS is applied to MTA in order to guarantee the quality of voice data in actual HFC Internet service network, it is possible to smoothly perform voice data transmission in narrow upstream band which is a problem in actual commercial HFC network We also proposed a method to improve VoIP service by improving QoS of voice data in HFC Internet service network.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제32권1B호
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• pp.1-10
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• 2007

We propose a new approach to accommodate bidirectional asymmetric traffic demands as well as unexpected dynamic internet traffic variation in the WDM mesh network by using optical networking technologies. In the proposed scheme, an intermediate node determines the optical path based on the switching statistics of IP router of the node which characterizes the Internet traffic variation, which in effect provides a dynamic and distributed traffic control over the network. It is expected to reduce the efficiency deterioration of RWA(Routing and Wavelength Assignment) due to the real-time variation of Internet traffic so that expandability and flexibility of the network can be enhanced. In this paper, we describe a methodology for traffic behavior analysis at a node, and the decision policy of the establishment/release of optical path. In addition, we evaluate the performance of the proposed scheme through the computer simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2011년도 춘계학술대회
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• pp.589-592
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• 2011

In this paper, bidirectional DC-DC converter is designed to cover up defects of fuel cell generating system like as low dynamic characteristic, unstable output and lack of storage ability by using bidirectional DC-DC Converter and supercapacitor that available to charge & discharge quickly, high efficient at charge & discharge and semi-permanent. Operating efficiency has been analyzed through simulation and examination. According to these design and data, hybrid system has been made and operation test, evaluation and results evaluation have been performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제27권8C호
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• pp.782-791
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• 2002

This paper discusses a far-end crosstalk (FEXT) canceller for twisted-pair transmission. Many twisted-pair systems such as fiber-to-the-curb (FTTC), very high-speed digital subscriber line (VDSL), and high-speed LAN systems, use frequency-division duplexing (FDD) for duplex transmission. It is shown that the maximum reach of FDD twisted-pair system is limited by the performance of its upstream channel, which is located at higher frequencies than the downstream channel. In order to improve the performance of such FDD transceiver, FEXT cancellation is introduced for the channel at higher frequencies. A system arrangement and its blind start-up procedure are studied when the FEXT canceller and equalizer are jointly adapted to combat channel intersymbol interference (ISI), FEXT, and other additive noise. The initial convergence and the steady-state behavior of the proposed twisted-pair system without requiring transmission of an ideal training sequence are investigated. Measured characteristics as well as analytical model of the FEXT channel are used to estimate the time span needed for the FEXT canceller. It is also shown that the memory span for the FEXT canceller is almost independent of the channel, thus making our results useful for the twisted-pair system over all different channels.