• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.305-310
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• 2008

최근 통신기술이 발달함에 따라 무선통신 주파수 대역폭은 더 넓어지게 되었고, 고집적 반도체 소자는 고속전철 시스템에 더 많이 적용되고 있다. 고속전철 시스템에서 사용되는 집적된 전력 반도체의 RFI (Radio Frequency Intereference, 라디오파 방해) 민감도 [또는 내성(耐性)]는 시스템의 안전에 많은 영향을 준다. 이 연구에서는 고속전철 시스템의 무선통신 주파수 대역에서 RFI 민감도 기준과 측정방법이 조사되었다.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2006년도 춘계 국제학술대회 논문집
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• pp.402-406
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• 2006

본 논문은 XSD(XML Schema Definition)기반의 XML 문서를 웹, 엑셀 환경에서 다양한 관점으로 볼 수 있도록 템플릿 서비스를 제공하기 위한 시스템이다. 템플릿 서비스는 데이터스킨 서버에서 스킨을 통하여 서비스되며, XML 문서를 다양한 문서로 변환할 수 있도록 한다. 예로 XML 문서를 HTML로 변경하는 경우 XSLT(Extensible Style Language Transformation) 를 사용할 수 있고, 엑셀 문서로 변환할 경우 엑셀 템플릿을 만들어 스킨으로 제공할 수 있다. 스킨은 다양한 방법으로 구현될 수 있으며, XML 문서에서 사용자가 원하는 문서로 만들기 위한 미들웨어 역할을 한다. 사용자는 데이터스킨 변환 서버에 접속하여 가지고 있는 XML 정보들을 차트, 그래프, 수식 등으로 쉽게 변환할 수 있을 뿐만 아니라 OWC(Office Web Component)로 쉽고 빠르게 문서를 변환 할 수 있도록 한다.

• ETRI Journal
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• 제28권2호
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• pp.247-249
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• 2006

In the development of a new wireless communications system, a versatile and accurate radio channel for indoor communications is needed. In particular, the investigation of radio transmission into buildings is very important. In this letter, we present an improved three-dimensional electromagnetic wave propagation prediction model for indoor wireless communications that takes into consideration building penetration loss. A ray tracing technique based on an image method is also employed in this study. Three-dimensional models can predict any complex indoor environment composed of arbitrarily shaped walls. A speed-up algorithm, which is a modified deterministic ray tube method, is also introduced for efficient prediction and computation.

• ETRI Journal
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• 제35권2호
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• pp.234-244
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• 2013

Internet protocol television (IPTV) service depends on the network quality of service (QoS) and bandwidth of the broadband service provider. IEEE 802.16j mobile multihop relay Worldwide Interoperability for Microwave Access networks have the opportunity to offer high bandwidth capacity by introducing relay stations. However, to actually satisfy QoS requirements for offering IPTV services (HDTV, SDTV, Web TV, and mobile TV) for heterogeneous users' requests, providers must use a video server for each IPTV service type, which increases the network load, especially bandwidth consumption and forwarding time. In this paper, we present a solution for forwarding IPTV video streaming to diverse subscribers via an 802.16j broadband wireless access network. In particular, we propose a new multicast tree construction and aggregation mechanism based on the unique property of prime numbers. Performance evaluation results show that the proposed scheme reduces both bandwidth consumption and forwarding time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.701-702
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• 2006

In this paper, we embodied the environment monitoring system that can acquire correct data in real-time. And we used module that is 2.4GHz IEEE 802.15.4 / Zigbee network for radio communication between nodes. The nodes sense the data of temperature, humidity, illumination periodically. The nodes store the data in their buffer and transmit. We confirmed that the system is in real-time as it is changed instantly due to the varying environment by the simulation Therefore, we can construct the efficient and correct system as applied this system to monitor the environment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.427-428
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• 2006

This paper presents an image fingerprinting scheme for the print-to-capture model performed by a photo printer and digital camera. When capturing an image by a digital camera, various kinds of distortions such as noise, geometrical distortions, and lens distortions are applied. slightly and simultaneously. In this paper, we consider several steps to extract fingerprints from the distorted image in print-and capture scenario. To embed ID into an image as a fingerprint, multi-bits embedding is applied. We embed 64 bits information as a fingerprint into spatial domain of color images. In order to restore a captured image from distortions a noise reduction filter is performed and a rectilinear tiling pattern is used as a template. To make the template, a multi-bits fingerprint is embedded repeatedly like a tiling pattern. We show that the extracting is successful from the image captured by a digital camera through the experiment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.133-134
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• 2006

In this paper the platform system for IEEE 802.15.4 Low Rate WPAN is designed and fabricated. IEEE 802.15.4 Low Rate WPAN system serves the functions and realization of home-area network. According to the IEEE 802.15.4 standard, there are two modes, One is BPSK modulation in 868/915MHz frequency band. The other is O-QPSK modulation in 2.45GHz frequency band. In this paper we implemented the platform system mounted in one PCB board in 868/915MHz frequency band of IEEE 802.15.4 Low Rate WPAN system. We measured that the platform system which consists of digital part and RF part has good performance. Also RF part is realized by design and fabrication of the RF transceiver IC. The key issue is to make the platform system which provides the function of Low Rate WPAN system to meet the requirement of IEEE 802.15.4 standards.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.55-56
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• 2006

Directional antennas are used to improve spatial reuse, but have the problem of deafness. The DUDMAC protocol uses the ORTS, OCTS, DDATA, and DACK mechanisms and a blocking algorithm for directional transmissions. In this paper, we propose a tone dual-channel directional MAC (Tone DUDMAC) protocol to improve spatial reuse. The Tone DUDMAC protocol uses the ORTS, DCTS, DDATA, and DACK mechanisms including the DDATA_tone and OCTS_tone. We use ORTS as that in DUDMAC because of location unawareness of neighbor's nodes. The DDATA_tone and OCTS_tone reduce a blocking area and improve spatial reuse. We confirm the throughput performance of the proposed MAC protocol by computer simulations using Qualnet ver.3.8 simulator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.263-264
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• 2006

In this paper, an efficient and fast algorithm to reduce calculation amount of FIR(Finite Impulse Responses) filtering is proposed. Proposed algorithm enables arbitrary size of parallel processing, and their structures are also easily derived. Furthermore, it is shown that the number of multiplication/sample is reduced, and number of instructions using MAC(Multiplication and Accumulation) processor are also reduced. For theoretical improvement, numbers of sub filters are compared with those of conventional algorithm. In addition to the theoretical improvement, it is shown that number of element for hardwired implementation are reduced comparison to those of the conventional algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.57-58
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• 2006

Ad hoc MAC protocols using directional antennas can be used to improve the network capacity by improving spatial reuse. But, the directional MAC protocols have the problem of deafness and have a poor throughput performance. The dual-channel DMAC protocol has been proposed to mitigate deafness and improve spatial reuse. In this paper, we propose a dual-channel DMAC protocol using the omnidirectional antenna for an out-of-band tone and directional antennas for control/data channels. In the proposed MAC protocol, an omnidirectional out-of-band tone mitigates deafness and directional antennas used in control/data channels improve spatial reuse and reduce interference packets. The throughput performance of the proposed MAC protocol is confirmed by computer simulations using Qualnet ver. 3.8 simulator.