• 한국멀티미디어학회논문지
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• 제18권4호
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• pp.492-498
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• 2015

In general, data packets from sensor nodes are transferred to the sink node in a wireless sensor networks. So many data packets are gathered around the sink node, resulting in significant packet collision and delay. In this paper, we propose an efficient packet transmission mechanism for multi-hop wireless sensor networks. The proposed mechanism is composed of two modes. One mode works between sink node and 1-hop nodes from sink. In this mode, data packets are transmitted in predefined time slots to reduce collisions. The other mode works between other nodes except sink node. In this mode, duplicated packets from neighbor nodes can be detected and dropped using some control signals. Our numerical analysis and simulation results show that our mechanism outperforms X-MAC and RI-MAC in terms of energy consumption and transmission delay.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1880-1884
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• 2004

The wavelet packet transform has been applied for QRS detection with squaring, window integration, and impulse filter techniques to cut down the false detection of QRS complex. This real time QRS detection has been performed on Simulink and Matlab. The correct QRS detection rates have reached to 99.75% in the experiment with 15 sets of ECG data from European ST-T database which are kept in Physionet.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.86-88
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• 2004

As the rapid incensement of the number of internet users has occurred recently, many multimedia application services have been emerging. To improve quality of service, traffic can be suggested to be classified with priority in EPON(Ethernet Passive Optical Network), which is supporting the multimedia application services. In this paper, multimedia application services treat bandwidth classifying device in serving both delay sensitive traffic for real-time audio, video and voice data such as VoIP(Voice over Internet Protocol), and nonreal-time traffic such as BE(Best Effort). With looking through existing mechanisms, new mechanism to improve the quality will be suggested. The delay performances and packet losses of traffic achieved by supporting bandwidth allocation of upstream traffic in suggested mechanism will be analyzed with simulation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1183-1186
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• 1998

Adaptive nois canceller can extract the noiseremoved spech in noisy speech signal by adapting the filter-coefficients to the background noise environment. A kind of LMS algorithm is one of the most popular adaptive algorithm for noise cancellation due to low complexity, good numerical property and the merit of easy implementation. However there is the matter of increasing misadjustment at voiced speech signal. Therefore the demanded speech signal may be extracted. In this paper, we propose a fast and noise robust wavelet packet adaptive noise canceller with NLMS-SUM method LMS combined algorithm. That is, we decompose the frequency of noisy speech signal at the base of the proposed analysis tree structure. NLMS algorithm in low frequency band can efficiently dliminate the effect of the low frequency noise and SUM method LMS algorithm at each high frequency band can remove the high frequency nosie. The proposed wavelet packet adaptive noise canceller is enhanced the more in SNR and according to Itakura-Satio(IS) distance, it is closer to the clean speech signal than any other previous adaptive noise canceller.

• 산업경영시스템학회지
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• 제20권41호
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• pp.103-112
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• 1997

In this paper, a nonhierarchial integrated information network with circuit switched and packet switched traffic is considered. It is assumed that circuit switched traffic is allowed to attempt an alternate path if the direct path is blocked, whereas packet switched traffic is not. The network uses a movable boundary scheme to allocate bandwidth dynamically. To analyze the performance of this type of network, EEBP(End to End Blocking Probability) is selected as a measure for circuit switched traffic and average time delay for packet switched traffic, respectively. EEBP and average time delay are derived analytically. Using the two proposed measure, the performance of the network under various bandwidth allocations and arrival patterns are observed. Moreover, the arrival rate of one link for circuit switched traffic is obtained from an approximation formula. Simulation results reveal the validity of the proposed approximation method.

• 한국산학기술학회논문지
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• 제6권6호
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• pp.513-520
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• 2005

60km 정도까지 중속으로 이동하는 단말들에게 1-3 Mbps의 고속의 전송속도를 제공하는 휴대 인터넷 시스템이 곧 상용화될 예정이다. 휴대 인터넷 시스템은 서로 다른 QoS를 요구하는 서비스들을 제공하므로, QoS를 고려한 효율적인 스케줄링 기법을 필요로 한다. 본 논문에서는 패킷 데이터 서비스를 지원하는 휴대인터넷 시스템에서 하향링크의 대기 패킷 버스트들이 겪는 평균 지연시간을 최소화하기 위한 여러 가지 패킷 스케줄링 방식을 비교 분석하였다. 시뮬레이션에 의한 분석결과 제안한 방식이 수율과 데이터 손실률 측면에서 우수함을 알 수 있었다.

• 한국멀티미디어학회논문지
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• 제10권12호
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• pp.1622-1631
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• 2007

To realize the wireless packet scheduler which efficiently considers both the effect of adaptive modulation and coding (AMC) scheme due to variable wireless communication channel information from physical layer and the QoS differentiation of multimedia services from internet protocol (IP) layer, this paper proposes a new downlink AMC-based priority queuing (APQ) scheduler which combines AMC scheme and service priority method in multimedia services at the same time. The result of numerical analysis shows that the proposed APQ algorithm plays a role in increasing the number of services satisfying the mean waiting time requirements per each service in multimedia services because the APQ scheme allows the mean waiting time of each service to be reduced much more than existing packet scheduler having only user selection processor.

• 한국경영과학회지
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• 제22권3호
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• pp.145-162
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• 1997

This paper an analytical model for estimating packet waiting times at stations in the DQDB network, where the most upstream station is saturated. This model is useful in comparing the extreme unfairness which downstream stations experience due to their geographical locations in accessing the medium. Each station is modeled as an M/G/1, where the service time is defined to be the time a packet spends in the transmission buffer. The service time is decomposed into five components, and in turn, the first and second moment of each component are derived in three different modes of operation. Simulation experiments are presented for model validation and results are discussed.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 추계학술발표논문집 (하)
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• pp.2467-2470
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• 2002

사용자의 필요를 충족시켜 줄 수 있도록 사용자에 대한 연구가 인터넷 비즈니스에서 활발히 이루어지고 있다. 인터넷 비즈니스와 마찬가지로 컴퓨터 게임 산업 분야에서도 이러한 연구가 필요하다. 하지만 컴퓨터 게임의 특성상 기존의 인터넷 비즈니스 방식과 같은 방법으로는 게이머(Gamer)의 행동을 알기 어렵다. 이러한 문제점을 해결하고자 본 논문에서는 패킷 마이닝(Packet Mining)을 이용한 게이머의 행위 분석 시스템을 제안하고자 한다. 이 시스템은 게이머들과 시스템 사이에 전달된 패킷을 수집하여 프로토콜별 텍스트 형태로 저장하고, 일정 시간이 흐르면 텍스트 형태로 저장된 패킷을 데이터베이스로 생성한다. 게이머 행위 분석 시스템은 이렇게 생성된 데이터베이스를 분석하고, 다양한 정보를 추출해내어 게이머의 행위를 분석한다.

• ETRI Journal
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• 제25권5호
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• pp.418-421
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• 2003

We propose an unbiased signal-to-interference ratio (SIR) estimator for the high speed downlink packet access (HSDPA) system. The proposed SIR estimator solves the problem of underestimation present in conventional SIR estimators and is suitable for channel quality measurement in the adaptive modulation and coding scheme of HSDPA, which requires accurate SIR estimation for optimum adaptive modulation and coding selection. Our analysis and simulation results demonstrate the improved estimation performance of the proposed SIR estimator.