• ETRI Journal
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• 제31권1호
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• pp.89-91
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• 2009

This letter considers the problem of resource sharing among a relay and multiple user nodes in cooperative transmission networks. We formulate this problem as a sellers' market competition and use a noncooperative game to jointly consider the benefits of the relay and the users. We also develop a distributed algorithm to search the Nash equilibrium, the solution of the game. The convergence of the proposed algorithm is analyzed. Simulation results demonstrate that the proposed game can stimulate cooperative diversity among the selfish user nodes and coordinate resource allocation among the user nodes effectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권4호
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• pp.1075-1089
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• 2024

In this paper, the optimizations of multi-hop cooperative molecular communication (CMC) system in cylindrical anomalous-diffusive channel in three-dimensional enviroment are investigated. First, we derive the performance of bit error probability (BEP) of CMC system under decode-and-forward relay strategy. Then for achieving minimum average BEP, the optimization variables are detection thresholds at cooperative nodes and destination node, and the corresponding optimization problem is formulated. Furthermore, we use conjugate gradient (CG) algorithm to solve this optimization problem to search optimal detection thresholds. The numerical results show the optimal detection thresholds can be obtained by CG algorithm, which has good convergence behaviors with fewer iterations to achieve minimized average BEP compared with gradient decent algorithm and Bisection method which are used in molecular communication.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.46-55
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• 1995

The multimedia documents becomes the most natural user interface for CSCW(Conputer Supported Cooperative Work) in distributed environment. The objective of this study is to propose a multimedia document architecture and to develop a system that can manage it well. The new architecture is for revisable documents and is the basic layer for hypermedia documents. A good document architecture for CSCW must support pointing, marking, and editing over a part of documents. The user views, version control, and full- content search are also desirable features. In this paper, we discuss the basic concept of a new document architecture for CSCW. We also present the user interfaces for spatio-temporal compositions of multimedia documents.

• 컴퓨터교육학회논문지
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• 제3권1호
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• pp.31-41
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• 2000

소집단협동학습은 학습자가 지식의 습득과정에 적극적으로 참여하는 학습자 중심의 학습방법으로 학업 성취와 함께 상호작용 기술의 습득, 학습의 동기유발, 나아가 창의성을 향상할 수 있는 교수-학습법이다. 정보의 급증과 함께 학습자의 능동적인 참여를 요구하는 현 시점에서 교육현장에서 시행되는 협동학습은 더욱 많은 관심을 받고 있다. 특히 교수매체로서 통신망의 도입은 기존에 교실에서 수행되어온 소집단 협동학습에 새로운 조명을 가져온다. 그러나 통신망이 협동학습을 도와줄 수 있다는 교육적 기대에도 불구하고 이를 수행하기 위한 구체적인 지침 및 전략에 관한 연구는 이루어지지 않고 있다. 본 연구에서는 소집단 협동학습에 유용한 통신망의 특성을 기반으로 기존의 협동학습 모형을 고찰하였다. 이를 기반으로 교실 수업에서 교수-학습의 도구로서 통신망기반 소집단 협동학습의 실천적인 전략을 제시하였다.

• Management Science and Financial Engineering
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• 제10권2호
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• pp.1-28
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• 2004

The integrated supply chain of business partners for e-Commerce in cyber space is defined as Logistics Chain if the cooperative activities are logistics-related. Logistics Chain could be managed effectively and efficiently by cooperative technologies of logistics chain execution. In this paper, we propose a routing and scheduling algorithm based on the Tabu search by adding geographical information into existing constraint for pick-up and delivery process to minimize service time and cost in logistics chain. And, we also consider an uncertainty processing for the tracing of moving object to control pick-up and delivery vehicles based on GPS/GIS/ITS. Uncertainty processing is required to minimize amount of telecommunication and database on vehicles tracing. Finally, we describe the Logistics Chain Execution (LCE) system to perform plan and control activities for postal logistics chain. To evaluate practical effects of the routing and scheduling system, we perform a pretest for the performance of the tabu search algorithm. And then we compare our result with the result of the pick-up and delivery routing plan generated manually by postmen.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4357-4378
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• 2017

In cooperative multi-relay networks, the relay nodes which are selected are very important to the system performance. How to choose the best cooperative relay nodes is an optimization problem. In this paper, multi-relay selection schemes which consider either single objective or multi-objective are proposed based on evolutionary algorithms. Firstly, the single objective optimization problems of multi-relay selection considering signal to noise ratio (SNR) or power efficiency maximization are solved based on the quantum bee colony optimization (QBCO). Then the multi-objective optimization problems of multi-relay selection considering SNR maximization and power consumption minimization (two contradictive objectives) or SNR maximization and power efficiency maximization (also two contradictive objectives) are solved based on non-dominated sorting quantum bee colony optimization (NSQBCO), which can obtain the Pareto front solutions considering two contradictive objectives simultaneously. Simulation results show that QBCO based multi-relay selection schemes have the ability to search global optimal solution compared with other multi-relay selection schemes in literature, while NSQBCO based multi-relay selection schemes can obtain the same Pareto front solutions as exhaustive search when the number of relays is not very large. When the number of relays is very large, exhaustive search cannot be used due to complexity but NSQBCO based multi-relay selection schemes can still be used to solve the problems. All simulation results demonstrate the effectiveness of the proposed schemes.

• 한국정보과학회논문지:시스템및이론
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• 제37권2호
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• pp.66-75
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• 2010

본 논문에서는 GPU(graphics processing unit)를 이용하여 오목의 인공지능 알고리즘 연산을 고속으로 수행하기 위한 효율적인 알고리즘 설계와 구현 방법을 제안한다. 본 논문에서 제안하는 게임 인공지능은 최소-최대 게임 트리(min-max game tree)와 유전 알고리즘(genetic algorithm)의 협업적 구조로 설계된다. 게임 트리와 유전 알고리즘의 평가함수(evaluation function) 부분은 많은 계산 량을 소모하지만 해 공간(solution space)의 수많은 후보 벡터에 대해 독립적으로 수행되기 때문에 본 논문에서는 이를 GPU 상에서의 대량 병렬처리를 통해 수행한다. NVIDIA CUDA(compute unified device architecture)환경에서의 실제 구현을 통해 CPU에서의 처리에 비해 게임 트리는 400배 이상의 수행 속도의 향상을, 유전 알고리즘은 300배 이상의 수행 속도의 향상을 각각 보였다. 본 논문에서는 스레드(thread)의 넘침(overflow)을 피하고 보다 효과적인 해 공간 탐색을 위해, 게임 트리를 이용하여 근방의 몇 단계까지 전역 탐색(full search)을 수행한 후 이후 단계는 유전 알고리즘을 이용하여 선별 탐색을 수행하는 협업적 인공지능을 제안한다. 다양한 실험 결과를 통해 제안하는 알고리즘은 게임의 인공지능을 향상시키고 게임의 규칙으로부터 주어진 시간 내에 문제를 해결할 수 있음을 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.720-723
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• 1997

This paper presents a cooperative control method for multiple robots. This method is based on local sensors. The proposed method integrates all information obtained by local perception through a set of sensors and generates commands without logical conflicts in designing control logic. To control multiple robots effectively, a global control strategy is proposed. These methods are constructed by using AND/OR logic and transition firing sequences in Petri nets. To evaluate these methods, the object-searching task is introduced. This task is to search an object like a box by two robots and consists of two sub-tasks, i.e., a wall tracking task and a robot tracking task. Simulation results for the object-searching task and the wall tracking task are presented to show the effectiveness of the method.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2006년도 춘계학술대회
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• pp.354-360
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• 2006

The purpose of this paper is to propose a securely personalized context-aware cooperative query that supports a multi-level data abstraction hierarchy and conceptual distance metric among data values, while considering privacy concerns around user context awareness. The conceptual distance expresses a semantic similarity among data values with a quantitative measure, and thus the conceptual distance enables query results to be ranked. To show the feasibility of the methodology proposed in this paper we have implemented a prototype system in the area of site search in a large-scale shopping mall.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.185-190
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• 2002

In distributed autonomous robotic systems (DARS), each robot must behave by itself according to its states ad environments, and if necessary, must cooperate with other robots in order to carry out their given tasks. Its most significant merit is that they determine their behavior independently, and cooperate with other robots in order to perform the given tasks. Especially, in DARS, it is essential for each robot to have evolution ability in order to increase the performance of system. In this paper, a schema co-evolutionary algorithm is proposed for the evolution of collective autonomous mobile robots. Each robot exchanges the information, chromosome used in this algorithm, through communication with other robots. Each robot diffuses its chromosome to two or more robots, receives other robot's chromosome and creates new species. Therefore if one robot receives another robot's chromosome, the robot creates new chromosome. We verify the effectiveness of the proposed algorithm by applying it to cooperative search problem.