• 한국컴퓨터정보학회논문지
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• 제17권11호
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• pp.189-196
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• 2012

본 논문은 동적 경제급전의 최적화 문제를 풀기 위해 교환 알고리즘을 제안하였다. 제안된 알고리즘은 첫 번째로, 발전단가 $C_i^{max}/P_i^{max}$가 비싼 발전기는 가동을 중지시키는 개념을 도입하여 총 요구량 $P_d$와 총 발전량 ${\Sigma}P_i$의 균형을 맞추었다. 다음으로 발전량을 $P_i=P_i{\pm}{\Delta}$, (${\Delta}$=1.0, 0.1, 0.01, 0.001)에 대해 $_{max}[F(P_i)-F(P_i-{\Delta})]$ > $_{min}[F(P_j+{\Delta})-F(P_j)]$, $i{\neq}j$이면 $P_i=P_i-{\Delta}$, $P_j=P_j+{\Delta}$로 발전량을 교환하는 방법을 적용하였다. 동적 경제급전 문제의 시험사례에 제안된 알고리즘을 적용한 결과 기존의 휴리스틱 알고리즘 최적화 발전비용을 크기 감소시켜 경제적인 이익을 극대화 시켰다.

• 한국경영과학회지
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• 제22권2호
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• pp.13-29
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• 1997

This paper considers a new routing problem, successive max-min connection ratio problem (SMCRP), arised in circuit telecommunication networks such as SONET and WDM optical transport network. An optimization model for SMCRP is established based on link-flow formulation. It's first optimization process is an integral version of maximum concurrent flow problem. Integer condition does not give the same connection-ratio of each node-pair at an optimal solution any more. It is also an integral multi-commodity flow problem with fairness restriction. In order to guarantee fairness to every node-pair the minimum of connection ratios to demand is maximized. NP- hardness of SMCRP is proved and a heuristic algorithm with polynomial-time bound is developed for the problem. Augmenting path and rerouting flow are used for the algorithm. The heuristic algorithm is implemented and tested for networks of different sizes. The results are compared with those given by GAMS/OSL, a popular commercial solver for integer programming problem.n among ferrite-pearlite matrix, the increase in spheroidal ratio with increasing fatigue limitation, 90% had the highest, 14.3% increasing more then 70%, distribution range of fatigue.
ife was small in same stress level. (2) $\sqrt{area}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of $\sqrt{area}_{max}$ may be used as a guideline for the control of inclusion size in the steelmaking.

• 한국통신학회논문지
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• 제26권6A호
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• pp.1089-1098
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• 2001

WRR 스케줄링 알고리즘은 계산의 단순성과 저 비용 구현의 장점을 가지고 있어 고속 패킷 스위칭 네트워크에서 널리 쓰이고 있지만 버스티한 트래픽에 대해서는 입력 트래픽을 일정 비율로 스케줄링하기 때문에 효율성이 낮다는 문제점이 있다. 또한, WRR 알고리즘은 ABR 서비스 클래스의 공평성 기준의 하나인 Maximum of MCR or Max-Min share 공평성을 만족시키지 못한다. 따라서 ABR 서비스를 위한 공평성 기준을 만족시키는 스케줄링 알고리즘이 필요하다. 따라서, 본 논문에서는 ABR 서비스를 위한 5가지 공평성 기준들 중 Maximum of MCR or Max-Min share를 만족시키는 스케줄링 알고리즘을 제안한다. 제안된 알고리즘이 공평성 기준을 만족시키고, 네트워크 자원을 각 ABR VC들에게 공평하게 할당해 주는지를 컴퓨터 시뮬레이션을 통하여 WRR 알고리즘과 비교, 분석한다.

• 한국컴퓨터정보학회논문지
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• 제21권4호
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• pp.81-88
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• 2016

The optimal solution of quadratic assignment problem (QAP) cannot get done in polynomial time. This problem is called by NP-complete problem. Therefore the meta-heuristic techniques are applied to this problem to get the approximated solution within polynomial time. This paper proposes an algorithm for a random type QAP, in which the instance of two nodes are arbitrary. The proposed algorithm employs what is coined as a max flow-min distance rule by which the maximum flow node is assigned to the minimum distance node. When applied to the random type QAP, the proposed algorithm has been found to obtain optimal solutions superior to those of the genetic algorithm.

• ETRI Journal
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• 제34권3호
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• pp.330-340
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• 2012

In many applications of wireless sensor actor networks (WSANs) that often run in harsh environments, the reduction of completion times of tasks is highly desired. We present a new time-aware, energy-aware, and starvation-free algorithm called Scate for assigning tasks to actors while satisfying the scalability and distribution requirements of WSANs with semi-automated architecture. The proposed algorithm allows concurrent executions of any mix of small and large tasks and yet prevents probable starvation of tasks. To achieve this, it estimates the completion times of tasks on each available actor and then takes the remaining energies and the current workloads of these actors into account during task assignment to actors. The results of our experiments with a prototyped implementation of Scate show longer network lifetime, shorter makespan of resulting schedules, and more balanced loads on actors compared to when one of the three well-known task-scheduling algorithms, namely, the max-min, min-min, and opportunistic load balancing algorithms, is used.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.24-33
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• 2012

This paper describes a multi-mode LDPC decoder which supports 19 block lengths and 6 code rates of Quasi-Cyclic LDPC code for Mobile WiMAX system. To achieve an efficient implementation of 114 operation modes, some design optimizations are considered including block-serial layered decoding scheme, a memory reduction technique based on the min-sum decoding algorithm and a novel method for generating the cyclic shift values of parity check matrix. From fixed-point simulations, decoding performance and optimal hardware parameters are analyzed. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a $0.18-{\mu}m$ CMOS cell library. It has 380,000 gates and 52,992 bits RAM, and the estimated throughput is about 164 ~ 222 Mbps at 56 MHz@1.8 V.

• 한국통신학회논문지
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• 제36권4A호
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• pp.414-422
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• 2011

모바일 WiMAX 표준 IEEE 802.16e의 블록길이 2,304 비트, 부호율 1/2을 지원하는 LDPC(low-density parity-check) 복호기를 설계하였다. 설계된 LDPC 복호기는 최소-합(min-sum) 알고리듬과 layered 복호를 기반으로 $96{\times}96$ 크기의 부행렬을 병렬로 처리하는 부분병렬 구조를 갖는다. 최소-합 알고리듬의 특징을 이용하여 메모리 용량을 감소시킬 수 있는 새로운 방법을 고안하여 적용함으로써 검사노드 메모리 용량을 기존의 방법보다 46% 감소시켰다. Verilog HDL로 설계된 LDPC 복호기를 $0.18{\mu}m$ CMOS 셀 라이브러리로 합성한 결과 174,181개의 게이트와 52,992 비프의 메모리로 구현되었으며, Eb/No=2.1dB의 AWGN 채널에 대해 평균 비트 오율 (BER)는 $4.34{\times}10^{-5}$이고, 100 MHz@1.8-V로 동작하여 약 417 Mbps의 성능을 갖는다.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1561-1570
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• 1997

This study explores the treatment of the max-value cost function over a parameter interval in parametric optimization. To avoid the computational burden of the transformation treatment using an artificial variable, a direct treatment of the original max-value cost function is proposed. It is theoretically shown that the transformation treatment results in demanding an additional equality constraint of dual variables as a part of the Kuhn-Tucker necessary conditions. Also, it is demonstrated that the usability and feasibility conditions on the search direction of the transformation treatment retard convergence rate. To investigate numerical performances of both treatments, typical optimization algorithms in ADS are employed to solve a min-max steady-state response optimization. All the algorithm tested reveal that the suggested direct treatment is more efficient and stable than the transformation treatment. Also, the better performing of the direct treatment over the transformation treatment is clearly shown by constrasting the convergence paths in the design space of the sample problem. Six min-max transient response optimization problems are also solved by using both treatments, and the comparisons of the results confirm that the performances of the direct treatment is better than those of the tranformation treatment.

• 한국산학기술학회논문지
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• 제10권12호
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• pp.3702-3707
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• 2009

본 논문은 Gray 부호화된 QAM (Quadrature Amplitude Modulation) 신호를 I 축 상에서 M개의 심벌을 갖는 M-PAM (Pulse Amplitude Modulation)과 Q 축 상에서 N개의 심벌을 갖는 N-PAM으로 분리한다. 수신된 심벌 신호를 비트 연판정 값으로 변환하기 위하여 Euclidean 거리를 이용한 근사화된 MAP (Maximum a Posteriori) 알고리듬을 제시한다. 기존의 Max-Log-MAP 방식은 일반 MAP 방식에서 사용하는 지수함수 혹은 로그함수 대신 심벌간 거리 비교를 통하여 구현 복잡도를 낮추었다. 그러나 심벌의 수가 증가 할수록 비교대상이 많아지므로 구현 복잡도가 증가하게 된다. 제안된 알고리듬은 사칙 연산에 의해 계산이 되기 때문에 직관적으로 구현복잡도가 낮아짐을 알 수 있다.

• ETRI Journal
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• 제28권3호
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• pp.291-300
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• 2006

A simple and general bit log-likelihood ratio (LLR) expression is provided for Gray-coded rectangular quadrature amplitude modulation (R-QAM) signals. The characteristics of Gray code mapping such as symmetries and repeated formats of the bit assignment in a symbol among bit groups are applied effectively for the simplification of the LLR expression. In order to reduce the complexity of the max-log-MAP algorithm for LLR calculation, we replace the mathematical max or min function of the conventional LLR expression with simple arithmetic functions. In addition, we propose an implementation algorithm of this expression. Because the proposed expression is very simple and constructive with some parameters reflecting the characteristic of the Gray code mapping result, it can easily be implemented, providing an efficient symbol de-mapping structure for various wireless applications.