• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 추계종합학술대회
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• pp.317-319
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• 2002

In this paper, a new method to get the optimum channel capacity of a Multiple-Input Multiple-Output (MIMO) system is presented. The proposed method exploits the diagonal structure o f channel matrix in order to maximize the channel capacity. The diagonal format of the channel matrix is formed by multiplying the transmitted signal with the precompensated channel (PCC) matrix. Numerical simulations show that the proposed method exploiting the diagonal structure of channel matrix could significantly increase the system capacity compared with the system without applying the diagonal structure of channel matrix.

• 한국통신학회논문지
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• 제32권12A호
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• pp.1238-1243
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• 2007

본 논문에서는 zero-forcing (ZF) 기반 다중 사용자 MIMO (multiple-input multiple-output) 시스템에서, 송신-처리-행렬을 구하기 위한 간단한 순차적 (recursive) nulling 행렬 계산 알고리즘을 제안한다. 제안한 방식은 채널 행렬의 부분 행렬을 써서 구한 nulling 행렬을 이용하여 전체 행렬의 nulling 행렬과 송신-처리-행렬을 구하는 방식으로써, 전체 채널 행렬을 이용하여 송신-처리-행렬을 구하는 기존 방식에 비해 계산량을 줄일 수 있다.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.48-57
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• 1999

Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

• Journal of Communications and Networks
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• 제18권6호
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• pp.892-901
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• 2016

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.896-901
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• 2002

The sound absorption coefficients for multiple layer perforated plate systems containing several compartments with airspaces and porous absorbing materials are estimated using the transfer matrix method developed in the previous paper. The absorption coefficients from transfer matrix method agree well with the values measured by the two-microphone impedance tube method for various combinations of perforated plates, airspaces or porous materials. Based on these results, a guidance for the design of multiple layer perforated plate systems combined with airspaces and porous absorbing materials is discussed in detail.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2010년도 하계학술대회
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• pp.9-11
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• 2010

Multiple-input multiple-output (MIMO) systems assisted by multi-relays with single antenna are considered. Signal transmission consists of two hops. In the first hop, the source node broadcasts the vector symbols to all relays, then all relays forward the received signals multiplied by each power gain to the destination simultaneously. Unlike the case of full cooperation between relays such as single relay with multiple antennas, in our case there is no closed form solution for optimal relay power gain with respect to minimum mean square error (MMSE). Thus we propose an alternative approach in which we use an approximation of the cost function based on rank-one matrix decomposition. As a cost function, we choose the trace of MSE matrix. We give several simulation results to validate that our proposed method obtains a negligible performance loss compared to optimal solution obtained by exhaustive search.

• 자원환경지질
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• 제17권4호
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• pp.283-288
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• 1984

Projection method has been used in the phase equilibria study. The projection is made through the saturated phase on the smaller chemical system from larger system. This decreases the number of phases which are included in the larger chemical system. In multiple projection containing plagioclase as a projection phase, there is a difference in matrix calculation when plagioclase is treated as a single composite component and separately as an albite and anorthite. The matrix calculation is considered to be more usable and easier in multiple projection. The value of the A component in the AFM system, which is the smaller system projected from the larger one, is effected and varies according to the change in the An content in plagioclase that is examined as an example.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.877-882
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• 2002

A new estimation model of predicting the sound absorption performance for multiple perforated plate sound absorbing system was developed using transfer matrix method. The proposed method was validated by comparing the calculated absorption coefficients of a single layer perforated plate with the values measured by the two-microphone impedance tube method far various porosity and cavity depth. The developed transfer matrix method was further applied to estimate the multiple layer perforated plates and it is shown that the estimated absorption coefficients generally agree well with the measured values.

• 정보처리학회논문지A
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• 제14A권2호
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• pp.107-116
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• 2007

본 논문에서는 Reed-Muller 전개식에 의한 다치 논리 회로의 구성에 관한 한 가지 방법을 제시하였다. 먼저, Perfect Shuffle 기법과 Kronecker 곱에 의한 다치 논리함수의 입출력 상호연결에 대하여 논하였고, GF(4)의 가산회로와 승산회로를 이용하여 다치 Reed-Muller 전개식의 변환행렬과 역변환행렬을 실행하는 기본 셀을 설계하였다. 이 기본 셀들과 Perfect Shuffle과 Kronecker 곱에 의한 입출력 상호연결 방법을 이용하여 다치 Reed-Muller 전개식에 의한 다치 논리 회로를 구현하였다. 제시된 다치 Reed-Muller 전개식의 설계방법은 모듈구조를 기반으로 하여 행렬변환을 이용하므로 동일한 함수에 대하여 타 방법과 비교하여 간단하고 회로의 가산회로와 증산회로를 줄이는데 매우 효과적이다. 제안된 다치 논리회로의 설계방법은 회선경로 선택의 규칙성, 간단성, 배열의 모듈성과 병렬동작의 특징을 가진다.

• 한국통신학회논문지
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• 제37권1A호
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• pp.25-33
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• 2012

랜덤 빔형성 기법은 사용자에게 심호 대 간섭 잡음비를 되먹임 받아 사용자를 선택하는 다중 안테나 전송 기법이다. 해당 기법은 사용자 수가 많은 환경일 경우 다중 사용자 이득에 따라 좋은 성능을 보이지만 사용자 환경이 적을 경우 다중 사용자 이득이 감소하여 좋은 성능을 얻기 어렵다. 이러한 문제를 해결하기 위해서 본 논문에서는 빔형성 메트릭스 변환 기법 및 이에 따른 사용자 선택 기법을 제안한다. 빔형성 메트릭스 변환 기법은 사용자로부터 되먹임 받은 정보를 기반으로 빔형성 메트릭스를 변환 시키며, 사용자 수가 적은 환경에서 기존 기법 보다 더 좋은 성능을 가진다. 또한, 제안하는 빔형성 메트릭스 변환 기법에 적합한 사용자 선택 기법을 이용하면 사용자 수의 증가에 따른 성능 향상을 기대 할 수 있다.