• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.128-130
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• 2016

The digital content industry is growing rapidly with the popularity of online content and mobile devices. This study estimates the technical efficiency of the online digital content industry, and identifies factors that could be causing inefficiency. Unlike most previous studies, which adopted input-oriented or output-oriented DEA model, this study employs non-oriented DEA model in order to deal with both input surpluses and output shortfalls. The input variables for the empirical analysis are number of companies and number of workers. The total sales is used as the output variables. The empirical results show that the technical efficiency of the online digital content industry is relatively low mainly due to the scale efficiency rather than the pure technical efficiency. This implies that industry-specific policies should be implemented in order to improve technical efficiency as well as to strengthen technological innovation capability. Therefore, it is expected that the results obtained in this study can be used as a good reference for helping the online digital content industry enhance their competitiveness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.561-569
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• 2005

Recently, the object-oriented design is the major paradigm for software development. Most systems are following this paradigm, but the past studies for a video conversation domain were not based on full-scale object-oriented design. Thus, this paper presents an systematical architecture design using UML for a video conversation system that is well-known and has high rate of usefulness. It analysis a video conversation system that has much demand of service as systematical functional/non-functional requirements, and the object-oriented design applying '4+1 View Model' guarantees the reusability of a component and makes it possible to extend a system by adding components as needed. Consequently, it is expected that the components of video conversation system designed by this paper will be useful the other video conversation systems and will be expanded to web environment.

• Journal of The Korean Astronomical Society
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• v.29 no.2
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• pp.83-91
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• 1996

We present a model that rotating primordial blackholes(PBHs) produced at the end of inflation generate the random, non-oriented primordial magnetic field. PBHs are copiously produced as the Universe completes the cosmic phase transition via bubble nucleation and tunneling processes in the extended inflation hypothesis. The PBHs produced acquire angular momentum through the mutual tidal gravitational interaction. For PBHs of mass less than 1013g, one can show that the evaporation (photon) luminosity of PBHs exceeds the Eddington limit. Thus throughout the lifetime of the rotating PBH, radiation flow from the central blackhole along the Kerr-geodesic exerts torque to ambient plasma. In the process similar to the Bierman's battery mechanism electron current reaching up to the horizon scale is induced. For PBHs of Grand Unified Theories extended inflation with the symmetry breaking temperature of $T_{GUT}\;\~\;10^{10}$ GeV, which evaporate near decoupling, we find that they generate random, non-oriented magnetic fields of $\~10^{-11}G$ on the last-scattering surface on (the present comoving) scales of $\~O(10)Mpc$.

• Journal of Korean Society for Quality Management
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• v.31 no.3
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• pp.114-125
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• 2003

In this paper, we deal with the problem of modeling of agent-based robot manufacturing cell. Its role is becoming increasingly important in automated manufacturing systems. For Object Oriented & Queueing Petri Nets (OO&QPNs), an extended formalism for the combined quantitative and qualitative analysis of different systems is used for structure and performance analysis of mobile robotic cell. In the case study, the OO&QPN model of a mobile robotic cell is represented and analyzed, considering multi-class parts, non-preemptive priority and alternative routing. Finally, the comparison of performance values between Shortest Process Time (SPT) rule and First Come First Serve (FCFS) rule is suggested. In general, SPT rule is most suitable for parts that have shorter processing time than others.

• Journal of Korea Multimedia Society
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• v.9 no.6
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• pp.693-699
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• 2006

Object-oriented databases (OODBs) have been adopted for managing non-standard applications such as computer-aided design (CAD), office document management and many multimedia applications. One of the major characteristics of OODBs is class hierarchy where a subclass is allowed to inherit the definitions defined on its superclasses. In this paper, I present the evaluation metrics for class hierarchy quality in OODBs. These metrics are developed to determine if a concurrency control scheme can achieve good performance or not on a given class hierarchy. I first discuss the existing concurrency control schemes for OODBs. Then I provide evaluation metrics based on structural information and access frequency information in class hierarchies. In order to discuss significance of the proposed performance metrics, an analytical model is developed. Analysis results show that the performance metrics are important factor in concurrency control performance. I consider both single inheritance and multiple inheritance. The proposed metrics can be used to provide guidelines on how to design class hierarchy of an OODB for maximizing the performance of concurrency control technique.

• Journal of the Korean Regional Science Association
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• v.14 no.2
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• pp.107-126
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• 1998

Since the election of governors and mayors by vote, many local governments in Korea establish long-range plans for their regional development. The major purposes of the plans are to set up development path for their communities and to devise economic development strategies. But most of the plans established thus formulated by the same method utilized in centralized political regime. This method is considered no longer appropriate to devise the long-range development plans for local government especially in the era of globalization and localization, where local governments behave independently, where local governments behave independently competition. We suggest an alternative way to establish such plans, based on the method employed in business sector. The plans, formulated in this way, are called strategy oriented long-range development plans. The underlying logic for the plans is non-linear one. The plans are issue oriented and focus more on process than outcome. Given that these features are properly incorporated in the plans, we expect that the strategy oriented long-range development plans can be genuine guidelines for local economic development in the years to come.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.530-533
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• 2000

Recently, Manufacturers have recognized the importance of recycling because of the limitation of natural resources and new and proposed laws and legislations that assign responsibility to manufacturer for the ultimate disposal of their products and the environmental problems. In this paper, products assembled recyclable parts and non-recyclable parts are collected after consumer usage and go into a plant. And the collected recyclable parts are disassembled through the disassembly process and have three attributes - re-usable attribute, re-manufacturing attribute and dumping attribute. In this situation, we deal with a production planning for recycle-oriented manufacturing system. The proposed model maximizing the profit in a system is formulated as a mixed-integer linear programming. And then a numerical example is used to evaluate the effectiveness of the proposed model

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.9
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• pp.669-678
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• 2003

A road-adaptive LQG control for the semi-active Macpherson strut suspension system of hydraulic type is investigated. A new control-oriented model, which incorporates the rotational motion of the unsprung mass, is used for control system design. First, based on the extended least squares estimation algorithm, a LQG controller adapting to the estimated road characteristics is designed. With computer simulations, the performance of the proposed LQC-controlled semi-active suspension is compared with that of a non-adaptive one. The results show better control performance of the proposed system over the compared one.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.626-634
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• 2000

The paper describes a new and rigorous mathematical model using counter-EMF for the rotor field oriented system with induction motor which uses the estimated speed and rotor flux based on a Model Reference Adaptive System as well as the real-time approach. The estimated speed and rotor flux is used for the speed and flux feedback control. The stability and the convergence of the estimator are improved on the basis of hyperstability theory for non-linear systems. The validity of the proposed method is verified by simulation and also the sensorless control was tested on the propulsion system simulator used for the development of Korean High-Speed Railway Train(KHSRT).

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.191-202
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• 2004

In this study, the project manager-oriented organization model has been verified by analysing it with forming a clear definition of detailed unitary duty entity to develop current non-efficient CM system constituted by functional organization with the decentralized responsibility and apply the model As a result from verification that the model provides valid solutions by comparing it with the existing, the model is better than the existing in cost savings, target profit sales rate, total rate of new on sales. Moreover, various activities in cost savings and cases where improvement is feasible are executed. However, the model caused some problems in organizational operation, project management and in division of duties so this study proposed improving management method