• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.4
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• pp.225-247
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• 2010

In this paper, we establish a two-competitive-prey and one-predator Holling type II system by introducing a proportional periodic impulsive harvesting for all species and a constant periodic releasing, or immigrating, for the predator at different fixed time. We show the boundedness of the system and find conditions for the local and global stabilities of two-prey-free periodic solutions by using Floquet theory for the impulsive differential equation, small amplitude perturbation skills and comparison techniques. Also, we prove that the system is permanent under some conditions and give sufficient conditions under which one of the two preys is extinct and the remaining two species are permanent. In addition, we take account of the system with seasonality as a periodic forcing term in the intrinsic growth rate of prey population and then find conditions for the stability of the two-prey-free periodic solutions and for the permanence of this system. We discuss the complex dynamical aspects of these systems via bifurcation diagrams.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.1
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• pp.48-54
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• 2023

Guided missiles are a one-shot system that finishes their purpose after being used once, and due to the long-term storage until launch, the storage reliability is calculated during development, and performance is maintained through periodic inspections until the life cycle arrives. However, the reliability standards applied in the development of guided missiles were established by analyzing data accumulated by the United States during long-term operation in the country, and since they are different from our environment, the 00 guided missiles that have been deployed in the armed forces for more than 10 years under the premise that there is a difference from actual reliability. As a result of verifying the appropriateness of the current inspection cycle by analyzing the actual reliability of the missile, the necessity of changing the inspection period was derived because it was higher than the predicted reliability. It is proposed to build and utilize a lifespan management system that can systematically collect all data such as shooting and maintenance results by classification, and to establish a reliable reliability standard based on the accumulated data.

• Educational Technology International
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• v.11 no.2
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• pp.25-41
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• 2010

Challenges brought by applications of advanced technologies in education call for new approaches that can best ensure the provision of quality e-learning experiences. This paper presents an ecological approach as one of such approaches to quality assurance in e-learning that can monitor, assess and improve the effectiveness and the links between the various elements of e-learning. The ecological model for QA in e-learning emphasizes interrelation transactions between elements (e.g. providers, learners, cultures and policies) and systemic integration of those elements, and stresses that all these elements within a QA system play an equal role in maintaining balance of the whole. The model focuses attention both on individual and societal/cultural environmental factors as cornerstones for QA efforts in e-learning. It addresses the importance of QA efforts directed at changing QA transactions from provider-centered to 'all stakeholder-oriented', from one-size-fits-all model to 'globally oriented, locally adaptive model' and from control framework to 'culture creation framework'.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.2
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• pp.183-204
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• 2014

US 911 incidents have changed all aviation security system in the world. Especially the US changed all existing system into new one. One of the most fundamental changes is aviation security acts, regulation and several programmes. Based on the new aviation security act enacted in 2001, several code of federal regulations have been amended to strengthen US aviation security system. These regulation also enable new aviation security programmes including several airline and airport security related programmes, K-9 programme, BDO programme and air marshall programmed. All the programmes enables US aviation security improvements. Also the creating of TSA based on the aviation and transportation security act has provided the enhancement of aviation security in US. The purpose of this thesis is studying the change of aviation security system in the US especiatly in terms of aviation security legislation perfective and comparing the system with Korean aviation security legal system and provides possible solution to enhance Korean aviation security legislation and structure.

• Research in Mathematical Education
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• v.12 no.1
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• pp.1-26
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• 2008

The concept field is defined as the schema of all equivalent definitions of a mathematics concept. Concept system is defined as the schema of a group concept network where there are mathematics relations. Proposition field is defined as the schema of all equivalent proposition sets. Proposition system is defined as a schema of proposition sets where one mathematics proposition at least is "derived" from the other proposition. CPFS structure that consists of concept field, concept system proposition field, proposition system describes more precisely mathematics cognitive structure, and reveals the unique psychological phenomena and laws in mathematics learning.

• Journal of Biomedical Engineering Research
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• v.26 no.5
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• pp.301-307
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• 2005

We introduce a new multimedia telemedicine system which is called Telemedicine for Real-time Emergency Multi-consultation(TREM), based on multiple connection between medical specialists. Due to the subdivision of medical specialties, the existing one-to-one telemedicine system needs be modified to a simultaneous multi-consulting system. To facilitate the consultation the designed system includes following modules: high-quality video, video conferenceing, bio-signal transmission, and file transmission. In order to enhance the operability of the system in different network environment, we made it possible for the user to choose appropriate data acquisition sources of multimedia data and video resolutions. We have tested this system set up in three different places: emergency room, radiologist's office, and surgeon's office. All three communicating systems were successful in making connections with the multi-consultation center to exchange data simultaneously in real-time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.430-434
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• 2001

Virtual manufacturing system is integrated computer model that represents the precise and whole structure of manufacturing system and simulates its physical and logical behavior in operation.[1] A virtual machine is computer model that represents a CNC machine tool and one of core elements of virtual manufacturing system. In this paper, it is emphasized that a virtual machine must be web-based system for serving information to all attendants in a real machine tool without the restriction of time or location, and then in the fault diagnosis, one of important modules of a virtual machine, the methods of both using the controller signal and web-based expert system are proposed.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1081-1089
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• 2008

Beginning in the 2007-2008 season, the men's pro-basketball league changed a foreigner selection method by introducing a draft system which leads to a tryout from the free agency system. Also in the same season, the woman's pro-basketball league changed its system from one that permitted foreign players to one that doesn't allow foreign player participation. The reason for this change is thought to be financial problems. However this institutional change brings about the reduction in the quality of basketball and it will affect spectators in a negative way. The empirical study attempted to analyze the effects which follows an institutional change in Korean men's pro-basketball. The research showed that the men's pro-basketball league wasn't affected at all due to foreigner selection method by a draft system that led to a tryout from the free agency system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.484-510
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• 2017

Network security is rapidly developing, but so are attack methods. Network worms are one of the most widely used attack methods and have are able to propagate quickly. As an active defense approach to network worms, the honeynet technique has long been limited by the closed architecture of traditional network devices. In this paper, we propose a closed loop defense system of worms based on a Software-Defined Networking (SDN) technology, called Worm-Hunter. The flexibility of SDN in network building is introduced to structure the network infrastructures of Worm-Hunter. By using well-designed flow tables, Worm-Hunter is able to easily deploy different honeynet systems with different network structures and dynamically. When anomalous traffic is detected by the analyzer in Worm-Hunter, it can be redirected into the honeynet and then safely analyzed. Throughout the process, attackers will not be aware that they are caught, and all of the attack behavior is recorded in the system for further analysis. Finally, we verify the system via experiments. The experiments show that Worm-Hunter is able to build multiple honeynet systems on one physical platform. Meanwhile, all of the honeynet systems with the same topology operate without interference.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.2
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• pp.57-65
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• 2002

Recently, there is growing recognition that we should protect an environment in all industries. As one of the OECD in the world trade market, we have to apply the Envirormentally Conscious Logistics System(ECLS) considering an environment seriously, and to implement environmentally conscious logistics activities. A packaging of entire logistics system have to also do it. Therefore, the objectives of this study were to discuss and to make an overture which an environmental packaging system of logistics system is by introducing a case study.