• 한국경영과학회지
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• 제22권3호
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• pp.23-36
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• 1997

In the design of telecommunication network, the network configuration using hubbing topology is useful for designing and managing the network efficiently : i. e. all of central offices (COs) are grouped into clusters. Each cluster has one hub consisting of large-scale transmission facilities like digital cross-connect systems and ATMs. In clustering process, the community of interest and geographical factor should be considered. However, there exists a tradeoff between two factors. One is to minimize total link costs for geographical factor and the other is to maximize the total intra-cluster traffics for community of interest. Hence, this can be solved by multiobjective linear programming techniques. In this paper, the problem under considerations is formulated as two p-median subproblems taking into considerations total costs and total intra-traffics, respectively. Then we propose the algorithm to solve the problem based on the concept of cost-traffic tradeoff. The algorithm enables to identify efficient cost-traffic tradeoff pairs. An illustration is also presented.

• 대한수학회보
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• 제53권5호
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• pp.1439-1446
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• 2016

The execution complexities of the major time memory data tradeoff methods are analyzed in this paper. The multi-target tradeoffs covered are the classical Hellman, distinguished point, and fuzzy rainbow methods, both in their non-perfect and perfect table versions for the latter two methods. We show that their computational complexities are identical to those of the corresponding single-target methods executed under certain matching parameters and conclude that the perfect table fuzzy rainbow tradeoff method is most preferable.

• Journal of Communications and Networks
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• 제11권5호
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• pp.445-454
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• 2009

Cooperative transmission protocols are always designed to achieve the largest diversity gain and the network capacity simultaneously. The concept of diversity-multiplexing tradeoff (DMT) in multiple input multiple output (MIMO) systems has been extended to this field. However, DMT constrains a better understanding of the asymptotic interplay between transmission rate, outage probability (OP) and signal-to-noise ratio. Another formulation called the throughput-reliability tradeoff (TRT) was then proposed to avoid such a limitation. By this new rule, Azarian and Gamal well elucidated the asymptotic trends exhibited by the OP curves in block-fading MIMO channels. Meanwhile they doubted whether the new rule can be used in more general channels and protocols. In this paper, we will prove that it does hold true in decode-and-forward cooperative protocols. We deduce the theoretic OP curves predicted by TRT and demonstrate by simulations that the OP curves will asymptotically overlap with the theoretic curves predicted by TRT.

• 산업공학
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• 제13권2호
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• pp.273-280
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• 2000

Time-tradeoff measures and healthy years equivalents were assessed and compared through an empirical study based on Multi-attribute utility theory. The study included 33 student subjects as a pilot study, and 54 end-stage renal disease patients in Wisconsin. The two outcome measures were compared with the survival duration of 1, 5, and 10 years. The results of the study show that the time-tradeoff method and the two-stage method did not lead to the same numerical quantities, although they aim to measure the same quantities (equivalent numbers of healthy years) theoretically. The healthy years equivalents involved more inconsistencies, and were less reliable than the time-tradeoff measures. Overestimation of the healthy years equivalents was observed. This seemed to be caused by the complex procedure of the two-stage method as well as by the preferences assessment biases. Based on the study experiences, the time-tradeoff measure would be recommended for problems involving generic medical applications and health policies.

• 정보보호학회논문지
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• 제17권2호
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• pp.73-81
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• 2007

본 논문에서는 스트림 암호 MICKEY의 두 가지 취약점에 대해서 논한다. 첫째, time-memory-data tradeoff 공격이 가능함을 보인다. 둘째, 상태 갱신 함수 (state update function)를 반복해서 적용할수록 내부 상태 (internal state)의 엔트로피가 감소하므로 다르게 시작된 키 스트림이 마침내 같아질 수 있다.

• 한국통신학회논문지
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• 제36권9A호
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• pp.776-783
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• 2011

본 논문에서는 적응형 복호 후 전송 (decode-and-forward) 중계 프로토콜이 송신을 위해 불완전한 채널정보를 사용할 때, 목적지 노드에서만 다중 안테나를 사용하는 경우, 릴레이 노드에서만 다중안테나를 사용하는 경우, 그리고 소스 노드에서만 다중 안테나를 사용하는 경우에 대한 diversity-multiplexing tradeoff (DMT) 상계 함수들을 유도하여 그 결과를 제시한다. 또한 소스 노드와 목적지 노드, 소스 노드와 릴레이 노드, 릴레이 노드와 목적지 노드 사이의 불완전한 채널정보들이 점근적 조건하에 있을 경우, 적응형 복호 후 전송 중계 프로토콜이 얻을 수 있는 다이버시티 이득을 조사한다.

• ETRI Journal
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• 제35권5호
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• pp.919-922
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• 2013

A MIMO multi-way relay channel with full data exchange in which K users exchange messages with each other via the help of a single relay is considered. For the case in which each link is quasi-static Rayleigh fading and the relay is full-duplex, the fundamental diversity-multiplexing tradeoff (DMT) is investigated, and we show that a compress-and-forward relay protocol can achieve the optimal DMT.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.114-116
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• 2015

This paper presents a Stochastic Time-Cost Tradeoff analysis system (STCT) that identifies optimal construction methods for activities, hence reducing the project completion time and cost simultaneously. It makes use of schedule information obtained from critical path method (CPM), applies alternative construction methods data obtained from estimators to respective activities, computes an optimal set of genetic algorithm (GA) parameters, executes simulation based GA experiments, and identifies near optimal solution(s). A test case verifies the usability of STCT.

• 한국통신학회논문지
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• 제38A권5호
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• pp.426-435
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• 2013

소스 노드, 목적지 노드, 릴레이 노드 중 하나의 노드에서 다중 안테나를 사용하는 특별한 세 가지 경우의 half-duplex (HD) dynamic decode and forward (DDF) 릴레이 프로토콜들에 대한 diversity multiplexing tradeoff(DMT) 함수를 유도하였다. 이 세 가지 릴레이 프로토콜들의 DMT 함수들을 상호 비교하였으며 nonorthogonal amplify-and-forward (NAF) 프로토콜들의 DMT 함수와 비교하였다.

• 한국수자원학회논문집
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• 제38권9호
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• pp.737-746
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• 2005

최적화란 목적함수가 최대 또는 최소가 되도록 하는 결정변수를 찾아가는 절차이다. 기존의 많은 연구자들은 최적해의 효율적인 탐색과정에 집중한 반면 최적화의 시작점이라 할 수 있는 목적함수 구성을 위한 연구는 상대적으로 미진한 것이 사실이다. 따라서 본 연구에서는 국내외에서 빈번히 사용되고 있는 가중평균법을 사용하여 tradeoff를 고려한 목적함수와 절대우선순위를 위한 가중값을 적용한 목적함수를 구성하여 표본추계학적 동적계획법을 통해 산정한 최적운영률을 비교하였다. 그 결과 절대우선순위를 위한 가중값을 적용한 경우가 보다 실제 저수지운영과 부합하는 결과를 나타내는 것을 확인할 수 있었다. 따라서 국내 다목적댐 운영계획에 보다 적합한 목적함수를 구성하기 위해서는 절대우선순위를 위한 가중값을 부여하여 목적함수를 구성하는 것이 타당한 것으로 판단된다.