• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.63-66
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• 1998

In the implementation of the simplex method program, the representation and the maintenance of basis matrix is very important, In the experimental study, we investigates Suhl's idea in the LU factorization and LU update of basis matrix. First, the triangularization of basis matrix is implemented and its efficiency is shown. Second, various technique in the dynamic Markowitz's ordering and threshold pivoting are presented. Third, modified Forrest-Tomlin LU update method exploiting sparsity is presented. Fourth, as a storage scheme of LU factors, Gustavson data structure is explained. Fifth, efficient timing of reinversion is developed. Finally, we show that modified Forrest-Tomlin method with Gustavson data structure is superior more than 30% to the Reid method with linked list data structure.

• 대한전기학회논문지
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• 제37권11호
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• pp.753-761
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• 1988

Partial Matrix Refactorization (PR) has been available for refactorization repeatedly. But this paper aims to present Modified PR(MPR), which is faster in (re) factorization speed and simpler in program than PR, but storage is almost as big as that of PR. MPR substitutes refactorization process of PR1 for Modifide Trifactortzation (MT) and, instead of PR 2, adds to PR1 the algoritm that calculates modified element values of modified row / cols. MT, which is subalgorithm for MPR, simplifies the algorithm by applying information vectors to currently used Trifactorization, and trifactorizes and refactorizes in high speed. The test results of Fast Decoupled Load Flow (FDLF) and Contingency Analysis useing Indexing Scheme and Optimal Ordering also prove that MPR is faster than PR.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.252-256
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• 2006

A low-power ECC check bit generator is presented with competent DRAM implementation with minimal speed loss, area overhead and power consumption. The ECC used in the proposed scheme is a variant form of the minimum weight column code. The spatial and temporal correlations of input data are analyzed and the input paths of the check bit generator are ordered for the on-line adaptable power savings up to 24.4% in the benchmarked cases. The chip size overhead is estimated to be under 0.3% for a 80nm 1Gb DRAM implementation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.174-176
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• 1997

This paper proposes a unit commitment scheduling method based on hybrid genetic algorithm(GA). When the systems are scaled up, conventional genetic algorithms suffer from computational time limitations because of the growth of the search space. So greatly reduce the search space of the GA and to efficiently deal with the constraints of the problem, priority list unit ordering scheme are incorporated as the initial solution and the minimum up and down time constraints of the units are included. The violations of other constraints are handled by integrating penalty factors. To show the effectiveness of the proposed method. test results for system of 10 units is compared with results obtained using other methods.

• 물과 미래
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• 제23권4호
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• pp.421-434
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• 1990

Horton의 차수법칙을 이용한 지형학적 수문응답모델로서 하천유역 상호간의 수문학정 상사성 문제를 해석하였다. 지형학적 응답함수의 구성은 Nash 모델을 이용하였으며, 응답함수의 최적화는 불완전 감미함수와 Rosso가 유도한 회귀방정식을 이용하였다. 본 방법의 적용성을 검토하기 위해 평창강 유역, 위천유역 그리고 보청천 유역에 대한 실측치를 이용하였으며, 수문응답에 대한 재현성을 모멘트법과 비교하였다. 분석결과 응답모델과 무차원 순간단위도는 미계측 유역의 유출해석이나 유역의 상사상 해석에 대해 적용할 수 있다고 판단되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.745-746
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• 2006

In this paper, we propose a new predictive coding scheme for color data of three-dimensional (3-D) mesh models. We exploit connectivity and geometry information to improve coding efficiency. After ordering all vertices in a 3-D mesh model with a vertex traversal technique, we employ a geometry predictor to compress the color data. The predicted color can be acquired by a weighted sum of reconstructed colors for adjacent vertices using both angles and distances between the current vertex and adjacent vertices.

• 대한산업공학회지
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• 제18권1호
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• pp.81-89
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• 1992

After much research on qualitative reasoning, the problem of ambiguities still hampers the practicality of this important AI tool. In this paper, the sources of ambiguities are examined in depth with a systems engineering point of view and possible directions to disambiguation are suggested. This includes some modeling strategies and an architecture of temporal inference for building unambiguous qualitative models of practical complexity. It is argued that knowledge of multiple levels in abstraction hierarchy must be reflected in the modeling to resolve ambiguities by introducing the designer's decisions. The inference engine must be able to integrate two different types of temporal knowledge representation to determine the partial ordering of future events. As an independent quantity management system that supports the suggested modeling approach, LIQUIDS(Linear Quantity-Information Deriving System) is described. The inference scheme can be conjoined with ordinary rule-based reasoning systems and hence generalized into many different domains.

• 한국IT서비스학회지
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• 제9권2호
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• pp.163-177
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• 2010

In this paper, we consider a channel ordering problem that seeks to maximize the service quality in mobile radio communication systems. If a base station receives a connection request from a mobile user, one of the empty channels belonging to the base station is assigned to the mobile user. In case multiple empty channels are available, we can choose one that incurs least interference with other channels assigned to adjacent base stations. However, note that a pair of channels that are not separated enough generates interference only if both channels are assigned to mobile users. That is, interference between channels may vary depending on the channel assignment sequence for each base station and on the distribution of mobile users. To find a channel assignment sequence that seems to generate minimum interference, we develop an optimization model considering various scenarios of mobile user distribution. Simulation results show that channel assignment sequence determined by the scenario based optimization model significantly reduces the interference provided that scenarios and interference cost are properly generated.

• 한국정보통신학회논문지
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• 제10권9호
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• pp.1654-1662
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• 2006

Ad-hoc 네트워크는 무선 링크들로 구성 된 멀티-홉 네트워크이다. 그리고 무선 링크의 전송 특성은 유선에 비해 보다 불안정 한 상태이다. 그러므로 Ad-hoc 네트워크에서는 패킷 손실이 자주 발생하고, 패킷 손실에 의한 TCP 연결 실패는 TCP 성능을 심각하게 저하시킨다. 또한, TCP 성능저하는 무선채널에서 데이터 패킷과 ACK 패킷의 충돌에 의해서 발생한다. 본 논문에서는 ODA(Ordering-Delayed ACK)지연 알고리즘을 제안하고, ODA 알고리즘과 지연 ACK 알고리즘을 이용하여 무선 Ad-hoc 네트워크의 성능을 향상시키고자 한다. 제안된 ODA알고리즘은 무선 Ad-hoc 네트워크에서의 수신 측에서 데이터 패킷의 수를 순서 적으로 증가시킨다. 본 논문에서는 NS-2를 이용하여 컴퓨터시뮬레이션을 수행하였다. 시뮬레이션 결과, 제안된 ODA 알고리즘은 기존의 지연 ACK 알고리즘에 비해서 무선 멀티-홉 Ad-hoc 네트워크 환경에서 채널 용량이 증가되고 네트워크의 성능이 향상됨을 확인할 수 있었다.

• 한국통신학회논문지
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• 제38A권4호
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• pp.350-359
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• 2013

본 논문에서는 협력 빔형성(Coordinated Multi-Point Coordinated Beamforming : CoMP CB) 시나리오에서 인접한 사용자들 때문에 발생되는 간섭(Inter User Interference : IUI)을 제거하기 위해 사용된 Block Diagonal Geometric Mean Decomposition(BD-GMD)기반의 IUI 제거 알고리즘을 Successive Signal to Leakage plus Noise Ratio(SSLNR) 환경에서의 ZF(Zero-Forcing)에 적용하여 누출 전력을 제거한다. 또 IUI 제거 알고리즘을 사용했을 시 문제가 되는 원하는 신호 전력(Desired signal power)의 크기를 크게 보장할 수 없다는 점을 보완하기 위해 적절한 채널 열 순열(Channel ordering)을 수행하여 원하는 신호의 전력을 높인다. IUI 제거 알고리즘 사용과 적절한 채널 열 순열을 통해 기존의 SSLNR-Zero-Forcing Tomlinson Harashima precoding(ZF-THP) 기법보다 더 나은 비트오류확률(Bit Error Rate : BER)성능을 낼 수 있다.