• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.1
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• pp.110-117
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• 2015

Spare part management is very important to products that have large number of parts and long lifecycle such as automobile and aircraft. Supply chain must support immediate procurement for repair. However, it is not easy to handle spare parts efficiently due to huge stock keeping units. Qualified forecasting is the basis for the supply chain to achieve the goal. In this paper, we propose an agent based modeling approach that can deal with various factors simultaneously without mathematical modeling. Simulation results show that the proposed method is reasonable to describe demand generation process, and consequently, to forecast demand of spare parts in long-term perspective.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.123-144
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• 2014

Wireless sensor networks are generally deployed for specific applications to accomplish certain objectives over a period of time. To fulfill these objectives, it is crucial that the sensor network continues to function for a long time, even if some of its nodes become faulty. Energy efficiency and fault tolerance are undoubtedly the most crucial requirements for the design of an information extraction protocol for any sensor network application. However, most existing software agent based information extraction protocols are incapable of satisfying these requirements because of static agent itineraries and large agent sizes. This paper proposes an Information Extraction protocol based on Multiple software Agents with Dynamic Itineraries (IEMADI), where multiple software agents are dispatched in parallel to perform tasks based on the query assigned to them. IEMADI decides the itinerary for an agent dynamically at each hop using local information. Through mathematical analysis and simulation, we compare the performance of IEMADI with a well known static itinerary based protocol with respect to energy consumption and response time. The results show that IEMADI provides better performance than the static itinerary based protocols.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.121-127
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• 2017

Recently, many patients in a hospital are threatened life by fire disaster. Because many patients like vulnerable people have more evacuation problem than ordinary person. So a patient who can escape by oneself with walking assistance device like crutches or wheelchair and another patient who can't escape by oneself are should be supported safety technologies and service. Earlier research of 'hospital evacuation' led by actual experiments or computer evacuation simulation. Actual experiment is effective to gain credibility of result but it is difficult for patients to experiment repeatedly and it requires consideration for spatial problem and economic problems. Although computer evacuation simulation have been used to solve these problems, almost have concluded only results based on velocity without evacuation device. In this study, evacuation results with support device application or not are analysed used by computer evacuation simulation based on MAS(Multi Agent System). As a result, it is drawn through proof of efficiency of evacuation device in the vertical space like stairs that can improve the evacuation plan for vulnerable people in the hospital.

• Journal of Korea Multimedia Society
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• v.23 no.6
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• pp.772-783
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• 2020

Tsunami is a frightful natural disaster that causes severe damages worldwide. To minimize the damage, South Korea has built a tsunami warning system and designated evacuation sites in the east and south coasts. However, such countermeasures have not been verified whether they are adequate to minimize casualties since tsunami rarely occurs in South Korea. Recently, due to increasing earthquakes in the west coast of Japan, the likelihood of South Korea entering the damage area of tsunami rises; thus, in this paper, we develops a simulator based on Unity game engine to simulate the evacuation from tsunami. In order to increase the fidelity of the simulation results, the simulator applies a tsunami simulation model that analyzes coastal inundation based on cellular automata. In addition, the objects included in tsunami evacuation, such as humans, are modeled as an agent model that determines the situation and acts itself, based on the discrete-event system specification (DEVS), a mathematical formalism for describing a discrete event system. The tsunami simulation model and agent models are integrated and visualized in the simulator using Unity game engine. As an example of the use of this simulator, we verify the existing tsunami evacuation site in Gwangalli Beach in Busan and suggest the optimal alternative site minimizing casualties.

• Korean Management Science Review
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• v.29 no.1
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• pp.153-168
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• 2012

Order allocation is one of the most important decision-making problems of firms having significant influences on performances of themselves and the whole supply chain. Existing researches about order allocation have mainly focused on evaluating capabilities of directly connected suppliers so that it is hard to consider effects and interactions from undirected connections over multiple lower-layers. To alleviate the limitation, this paper proposed a novel approach to order allocation using structural hole. By applying the concept of structural hole to the supply network, we could evaluate the structural supplying powers of firms with respect to both of direct and indirect connections. In the proposed approach, we derived a methodology to measure the potential supplying power of each firm by modifying the effective size as one of the measurements of structural hole and then, proposed its application, the structural hole based order allocation strategy. Furthermore, we conducted the agent based modeling of supply chain to perform the decision-making process of order allocation and simulated the proposed strategy. As a results, by coping with the variance of demand more stably, it could improve the performance of supply chain from the aspects of fill rate, inventory level and demand-supply balance.

• 한국ITS학회:학술대회논문집
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• 2005.11a
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• pp.186-190
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• 2005

• Korean Management Science Review
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• v.27 no.1
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• pp.61-73
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• 2010

Purpose of the War history's study is getting instruction by analyzing victory and defeat factor. This study is studied by qualitative form in war study mainly. In case recording literature is full, victory and defeat factor analysis is easy, but occasionally definite analysis that recording literature is feeble is difficult. Also, when it is battle result that escape common sense, about victory and defeat factor, various estimations are brought. As such example, there is Myeong-Ryang sea-battle at Japanese Invasion of Korea in 1592 and Korea(Cho-Sun) naval forces did big victory in 13 vs. 133 numerical inferiorities. This study presented method of study that using agent based simulation model for quantitative analysis of these victory and defeat factor.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.321-324
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• 2001

The robot soccer simulation game is a dynamic multi-agent environment. In this paper we suggest a new reinforcement learning approach to each agent's dynamic positioning in such dynamic environment. Reinforcement Beaming is the machine learning in which an agent learns from indirect, delayed reward an optimal policy to choose sequences of actions that produce the greatest cumulative reward. Therefore the reinforcement loaming is different from supervised teaming in the sense that there is no presentation of input-output pairs as training examples. Furthermore, model-free reinforcement loaming algorithms like Q-learning do not require defining or loaming any models of the surrounding environment. Nevertheless it can learn the optimal policy if the agent can visit every state-action pair infinitely. However, the biggest problem of monolithic reinforcement learning is that its straightforward applications do not successfully scale up to more complex environments due to the intractable large space of states. In order to address this problem, we suggest Adaptive Mediation-based Modular Q-Learning(AMMQL) as an improvement of the existing Modular Q-Learning(MQL). While simple modular Q-learning combines the results from each learning module in a fixed way, AMMQL combines them in a more flexible way by assigning different weight to each module according to its contribution to rewards. Therefore in addition to resolving the problem of large state space effectively, AMMQL can show higher adaptability to environmental changes than pure MQL. This paper introduces the concept of AMMQL and presents details of its application into dynamic positioning of robot soccer agents.

• Journal of the Korea Computer Industry Society
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• v.3 no.8
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• pp.1049-1062
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• 2002

As the distributed resources in the networks have become increasingly popular, the accesses to these resources having been activated. Especially, the accesses to the distributed resources using the mobile agent technologies provide the mechanisms supporting mobility with mobile users as well as the dynamic accesses to the resources in the fixed networks. Proxy-based mobile agent model is defined as mobile agent network model which allocates the hierarchical domains to the distributed resources changed dynamically, assigns one proxy server for each domain, and promotes the management and the cooperation of the mobile agents. In this paper, we introduce the architecture and the execution scenario for proxy-based mobile agent model which is suitable for the hierarchical management domains. In simulation, we evaluate the proxy server's route optimization functionality and the performance reducing execution time of the mobile agents.

• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.9-18
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• 2008

Unlike conventional researches, we are able to i) compare the fuzzy logic based BBA with non-fuzzy BBA for verifying the effective performance of the proposed fuzzy logic application ii) dynamically respond to the intrusion using BBA whereas the previous IDS was responding statically and iii) expect that this would be a cornerstone for more practical application researches (analyzing vulnerability and examining countermeasures, etc.) of security simulation. Several simulation tests performed on the targer network will illustrate our techniques. And this paper applies fuzzy logic to reduce the false negative that is one of the main problems of IDS. Intrusion detection is complicated decision-making process, which generally involves enormous factors about the monitored system. Fuzzy evaluation component model, which is a decision agent in the distributed IDS, can consider various factors based on fuzzy logic when an intrusion behavior is detected. The performance obtained from the coordination of intrusion detection agent with fuzzy logic is compared against the corresponding non fuzzy type intrusion detection agent. The results of these comparisons allow us to evaluate a relevant improvement on the fuzzy logic based BBA.