• Journal of applied mathematics & informatics
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• 제14권1_2호
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• pp.81-96
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• 2004

The level-m scaled circulant factor matrix over the complex number field is introduced. Its diagonalization and spectral decomposition and representation are discussed. An explicit formula for the entries of the inverse of a level-m scaled circulant factor matrix is presented. Finally, an algorithm for finding the inverse of such matrices over the quaternion division algebra is given.

• 방송공학회논문지
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• 제10권2호
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• pp.166-173
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• 2005

본 논문에서는 직교 주파수 분할 다중 접속 (orthogonal frequency division multiplexing, OFDM) 시스템에서 MP (matching pursuit) 알고리듬을 이용하는 이동 채널 추정법을 제안한다. OFDM 시스템에서 기존의 채널추정 알고리듬으로 쓰이는 LS (least square) 알고리듬은 잡음의 영향으로 채널 추정 오류의 가능성을 가지고 있다. 본 논문에서는 MP 알고리듬을 이용하여 스파스(sparse)형태의 채널을 추정함으로써 다중경로 신호가 없다고 가정되는 시간 구간에서 발생될 수 있는 잡음에 의한 영향을 줄인다. 그리고 연속으로 전송되는 파일럿 정보를 이용하여 변화하는 채널을 추정한다. 64QAM,그리고 이동 다중 경로 페이딩 채널에 대해서 심볼 오율을 측정하여 제안된 알고리듬과 LS알고리듬의 성능을 비교한다.

• ETRI Journal
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• 제29권3호
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• pp.329-335
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• 2007

This paper considers a timeslot assignment problem in an interactive satellite multimedia (ISM) system with digital video broadcast-return channel via satellite (DVB-RCS). The timeslot assignment problem is formulated as a binary integer programming to maximize the overall weighted throughput and is shown to be NP-hard. Thus, three real-time heuristic algorithms including ratio-based, packet-size (PS)-based, and transmission gain (TG)-based are derived, and some computational experiments are made. Considering the results, the ratio-based heuristic algorithm is demonstrated to be the most effective and efficient. We propose adapting the ratio-based heuristic algorithm to the timeslot assignment problem to greatly improve the ISM system utilization.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.819-822
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• 2004

To transmit MPEG-2 video on an erroneous channel, a number of error control techniques He needed. Especially, error concealment techniques which can be implemented on receivers independent of transmitters are essential to obtain good video quality. In this paper, a motion adaptive boundary matching algorithm (MA-BMA) is presented for temporal error concealment. Before carrying out BMA, we perform error concealmmt by a motion vector prediction using neighboring motion vectors. If the candidate of error concealment is rot satisfied, search range and reliable boundary pixels are selected by the motion activity or motion vectors ane a damaged macroblock is concealed by applying the MA-BMA. This error concealment technique reduces the complexity and maintains PSNR gain of 0.3 0.7dB compared to the conventional BMA.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.923-926
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• 2001

In this paper, we investigate a new approach pilot-symbol-aided channel estimation for orthogonal frequency division multi-plexing (OFDM) systems. Until now, lots of channel estimation methods are proposed. The pilot symbol assisted modulation (PSAM) has good performance. But, our proposed Algorithm has more good performance than the conventional PSAM system. Our algorithm is that channel estimation performance using the less inserted pilot-symbols systems is almost same to the two times inserted pilot-symbols system. The proposed method is highly robust to fast Rayleigh fading channel. Simulation results are presented to demonstrate the performance of our proposed algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.73-76
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• 2001

It is well-known that the convergence rate gets worse when an input signal to an adaptive filter is correlated. In this paper we propose a new adaptive filtering algorithm that makes the convergence rate highly improved even for highly correlated input signals. By introducing an orthogonal constraint between successive input signal vectors, we overcome the slow convergence problem caused by the correlated input signal. Simulation results show that the proposed algorithm yields highly improved convergence speed and excellent tracking capability under both time-invariant and time varying environments, while keeping both computation and implementation simple.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 봄 학술발표논문집 Vol.29 No.1 (A)
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• pp.676-678
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• 2002

In this work, we present the novel scheduling algorithm of the multimedia data retrieval for the mobile disk drive. Our algorithm is focused on minimizing the power consumption involved in data retrieval from the local disk drive. The prime commodity in mobile devices is the electricity. Strict restriction on power consumption requirement of the mobile device put unique demand in designing of its hardware and software components. State of the art disk based storage subsystem becomes small enough to be embedded in handhold devices. It delivers abundant storage capacity and portability. However, it is never be trivial to integrate small hard disk or optical disk drive in handhold devices due to its excessive power consumption. Our algorithm ARM in this article generates the optimal schedule of retrieving data blocks from the mobile disk drive while guaranteeing continuous playback of multimedia data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.98-100
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• 1997

This paper proposes a mathematical model of impact force generated by collision between landing foot and ground, by which a dynamic analysis and a supplementation of existing stability criteria are made. By using the proposed dynamic analysis, an energy-optimized gaital algorithm is proposed. To prove the effectiveness of the algorithm, simulation results are shown compared to the result of previous gaital algorithm.

• 대한산업공학회지
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• 제34권3호
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• pp.289-295
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• 2008

The shared-route decision algorithms in multicasting communications networks to provide the internet-based services such as IPTV, remote education/health, and internet broadcasting are presented. The three main measures of maximum delay, average delay and estimated delay between each node and member are adopted. Under the Mesh network with the uniform random cost between each node, the algorithm's performance is compared to the optimal solution with the minimum cost by all enumeration. The simulation results show that the algorithm using the estimated delay outperforms the other two methods.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.194-197
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• 2002

This paper considers the problem of routing connections in a optical multi tree networks using WDM (Wavelength Division Multiplexing), where each connection between a pair of nodes in the network is assigned a path through the network and a wavelength on that path, so that connections whose paths share a common link in the network are assigned different wavelengths. The problem of optimal coloring of the paths on the optical multi-networks is NP-hard[1], but if that is the coloring of all paths, then there exists efficient polynomial time algorithm. In this paper, using a "divide & conquer" method, we give efficient algorithm to assign wavelengths to all the paths of a tree network based on the theory of [7]. Here, our time complexity is 0(n4log n).