• 융합신호처리학회논문지
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• 제2권3호
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• pp.32-38
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• 2001

다중 채널을 사용하는 디지털 멀티톤 데이터 전송 시스템의 성능은 전송 채널의 영향으로 발생하는 심벌간의 간섭 잡음에 제한적이다. ISI를 제한하여 시스템의 데이터 전송 성능을 향상시키는 목적으로 전송 채널 임펄스 응답의 길이를 단축시키는 기법과 전송 채널의 주파수 특성을 향상시키는 기법을 합성하는 채널 등화 기법을 제안하였다. 수렴 속도가 빠른 칼만 알고리즘 및 구현 상 효율적인 LMS 알고리즘을 적용하여 제안한 등화기를 구현한다. 구현된 등화기를 필터 뱅크 기반 다중반송파 데이터 전송 시스템에 적용한 결과, 기존의 시스템의 성능보다 우수한 신호 대 간섭 잡음 비를 얻을 수 있음을 컴퓨터 시뮬레이션을 통하여 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2068-2086
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• 2011

Based on the quincunx sub-sampling grid, the New Interleaved Hierarchical INTerpolation (NIHINT) method is recognized as a superior pyramid data structure for the lossless and progressive coding of natural images. In this paper, we propose a new image interpolation algorithm, Edge Adaptive Hierarchical INTerpolation (EAHINT), for a further reduction in the entropy of interpolation errors. We compute the local variance of the causal context to model the strength of a local edge around a target pixel and then apply three statistical decision rules to classify the local edge into a strong edge, a weak edge, or a medium edge. According to these local edge types, we apply an interpolation method to the target pixel using a one-directional interpolator for a strong edge, a multi-directional adaptive weighting interpolator for a medium edge, or a non-directional static weighting linear interpolator for a weak edge. Experimental results show that the proposed algorithm achieves a better compression bit rate than the NIHINT method for lossless image coding. It is shown that the compression bit rate is much better for images that are rich in directional edges and textures. Our algorithm also shows better rate-distortion performance and visual quality for progressive image transmission.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.597-600
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• 2009

Sound transmission loss (TL) is experimently investigated on the multi-layered panel used for the floor of a tilting train. Measurement of the intensity transmission loss is performed according to ASTM E 2249-02. The floor structure consists of corrugated steel panel, glass wool, plywood and cover. On the corrugated steel panel, TL drop by local resonance is considered and the TL improvement effect by damping treatment is estimated. Total sound transmission loss of the entire floor structure is obtained and the contribution of each layer is examined.

• 한국인터넷방송통신학회논문지
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• 제11권3호
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• pp.123-126
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• 2011

스마트폰과 스마트패드의 사용자가 급격하게 증가됨에 따라 무선랜 AP의 설치가 확대되고 있다. 따라서 향후에 무선랜을 이용한 인터넷 지역 방송 서비스가 활성화될 것이다. 그러나 다수의 단말기로 단방향으로 데이터를 전송하는 방송 기술의 특성상 전송 오류가 발생하는 문제가 발생한다. 본 논문에서는 BER(Bit Error Rate)과 데이터 프레임 길이에 따른 데이터 프레임 오류율(FER: Frame Error Rate)에 대해 분석하여 방송 환경에 따른 적절한 데이터 프레임 길이를 제시하며, 동일한 방송 데이터 프레임을 여러 번 전송하여 실제적으로 FER을 줄이는 방법을 제안한다.

• 전자공학회논문지S
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• 제34S권12호
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• pp.50-59
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• 1997

A wireless LAN medical information transmission system is useful for patients who need mobility in a local area environment. This paper proposes a method using WLAN(wireless local area network) and implements a stand-alone system with MAC(meidum access control) layer protocol referenced IEEE 802.11 draft standard. The system consists of a 8bit-microprocessor which handles media access control protocol and a WL100(GEC Plessey) chip which takes care of phsical layer specific routines and uses a RF module DE6003(GEC Plessey). The major features of the implemented system are the CSMA/CA protocol used a consecutive DATA-ACK trasmission method which yields more effective bandwidth allocation for asyncronous traffic transmission and the modified PCF protocol for time-bounded traffic transmission, which operates in ad-hoc network topology apart from IEEE 802.11 draft standard confirm PCF mode operate in infrastruture topology.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.82-89
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• 2007

Sound transmission characteristics are investigated on the corrugated steel and aluminium extruded panels used for railway vehicles. Sewell-Sharp-Cremer(SSC) model, equivalent orthotropic plate model and equivalent mass law are applied to predict the sound transmission loss. The predicted values of the sound transmission loss are compared with the measured values. The reliability and the limitation of the prediction models are investigated. For the corrugated panels and honeycomb panels, the coincidence and local resonance severely deteriorate the sound insulation performance around the corresponding frequency bands. The result of the study shows that the equivalent orthotropic plate model and the SSC model can be used as good prediction models, if the coincidence frequency or local resonance frequency is correctly applied.

• 한국컴퓨터정보학회논문지
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• 제22권12호
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• pp.95-100
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• 2017

In this paper, we propose a zone based ad hoc network construction scheme which support ad hoc path between nodes in local IoT networks consisting of IoT devices with the constrained feature, such as low power, the limited transmission rate and low computing capacity. Recently, the various routing protocols have been studied to support ad hoc networking of local IoT environments. This is, because basis RPL protocol is deigned to be used for the connecting service with Internet through gateway, ad hoc path between nodes in local IoT networks is not supported in basis RPL protocol. Thus, in this paper, the proposed routing scheme provides both ad hoc path and Infra path through gateway, supporting basis RPL protocol simultaneously. Through simulation, we show that the proposed routing scheme with zone based path selection scheme improves the performance of the success rate of end-to-end data transmission and the end-to-end delay, compared to basis RPL protocol.

• 대한전기학회논문지:전력기술부문A
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• 제54권1호
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• pp.43-50
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• 2005

The presence of transmission congestion may reduce the market size and split the bulk power system into smaller systems. Consequently, this can be a key factor to the increase in market price. This paper analyzes the effect of exercising local market power on the market price, and derives a range of indices which quantify the degree and incentive of local market power through statistical analysis in an electricity market with uniform pricing scheme. The applicability and effectiveness of the derived indices on competitive electricity markets are demonstrated on the Korea electricity market.

• 전기학회논문지
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• 제58권5호
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• pp.885-890
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• 2009

A fault location algorithm using estimated local source impedance after a fault is proposed in this paper. The method uses after fault data only at the local end. It uses the negative sequence current distribution factor for more accurate estimation. The proposed algorithm can keep up with the variation of the local source impedance. Therefore, the proposed algorithm especially is valid for a transmission line interconnected to a wind farm that the equivalent source impedance changes continuously. The performance of the proposed algorithm was verified under various fault conditions using the Simpowersystem of MATLAB Simulink. The proposed algorithm is largely insensitive to the variation in fault distance and fault resistance. The test results show a very high accurate performance.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.672-676
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• 2010

In a railway vehicle, corrugated steel panel is widely used for the floor structure because of its high bending stiffness and light weight. However, this panel shows lower sound insulation performance than that of the flat plate with the same weight. Especially, in a particular frequency region, transmission loss(TL) rapidly decreases and it results in the deterioration of sound insulation performance of the overall floor structure. This study identifies that the severe decrease in TL is caused from the local resonance of the periodic corrugated structure. TL decrease by local resonance is investigated by experiment and finite element analysis. Finally, design modification of the corrugation is proposed to improve TL and the effect is verified by experiment.