• Journal of Information Technology Services
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• v.13 no.4
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• pp.109-122
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• 2014

Demand of spectrum resource is tremendously increasing recently and this trend will continues in the future due to the wide spread of IT services based on cloud computing and Internet of Things technology and as well as smart devices. Recently, spectrum sharing technology has drawn attention to the spectrum policy makers as a promising way to overcome the shortage problem of scarce spectrum resource. To succeed in commercialization of spectrum sharing technology, it is necessary to prospect the future business ecosystem of spectrum sharing and develop appropriate policies and laws at the same time along with the advance of spectrum sharing technology. The purpose of this paper is to analyze casual relationships between enablers in future business ecosystem of spectrum sharing and propose policies to vitalize spectrum sharing ecosystem based on a system dynamics causal map proposed in the previous research. With the causal map and system dynamics method, it is possible to analyze feedback loops exist in the business ecosystem of spectrum sharing and build policies which optimize positive dynamics in business ecosystem of spectrum sharing. As a result, policy leverages were found in four areas; spectrum supply, spectrum demand, spectrum quality and technology, and spectrum transaction cost. For those policy leverages, 13 policies were identified and intervention timing for each policy was discussed. Finally, the promotion policies of government and market participants to vitalize spectrum sharing ecosystem were discussed.

• Korean System Dynamics Review
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• v.8 no.1
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• pp.151-171
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• 2007

Without exception, diverse LULU(Locally Unwanted Land Use) facilities have been under the location conflict, especially between the public government units and local residents. In spite of repeated trials-and-errors, literally, the location conflict has shown no sign of improvement over time in Korea. As practical means to tackle these issues, this study focuses on divulging explicit and implicit relationships among key factors derived from the location conflict on the LULU facilities. Here, major research variables cover residents' agreement, residents' perception, compensation expectation, and public opinion. As the location conflict on the LULU facilities could be strengthened or resolved by the dynamic feedback system, it applies basic tools geared toward causal loop diagramming. After repeated experiments, the study highlights the fact that the residents' perception, compensation expectation, and public opinion, individually and collectively, exert significant impact on the residents' agreement ratio.

• The Journal of Fisheries Business Administration
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• v.39 no.1
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• pp.17-42
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• 2008

This study tried to build a structure model for the Korean flatfish aquaculture market by a system dynamics approach. A pool of several factors to influence the market structure was built. In addition, several reasonable factors related to the flatfish aquaculture market were selected to construct the causal loop diagram (CLD). Then the related stock/flow diagrams of the causal loop diagrams were constructed. This study had been forecasting a production price and supply, demand, and consumption volume for the flatfish market by a monthly basis, and then made some validation to the forecasting. Finally, four governmental policies such as import, storage, reduction of input, and demand control were tentatively evaluated by the created model. As a result, the facts that the demand control policy is most effective, and import and storage policies are moderately effective were found.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.391-402
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• 2006

Most previous studies considering inventory models for imperfect quality assumed that defective items could be completely detected by inspection and fixed before delivery to customers. This makes it difficult to adopt their research results to practice. This study reduces the assumption of perfect inspection, and presents an inventory model considering reverse logistics caused by imperfect inspection. System dynamics model is used to describe complex and dynamic problem and to show the effect of imperfect inspection on profit by simulation. Then, this article provides a guideline for the inspection policy which provides the maximum profit.

• ETRI Journal
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• v.20 no.1
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• pp.1-15
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• 1998

The recent technological and industrial revolution dictates a new approach in constructing Korean Information Infrastructure. Lacking past data on the newly emerging markets, econometrics methodologies cannot accurately forecast future path of advanced networks, let alone dynamic impacts of public policies. In this paper, we have built a system dynamics model of the Korean Information Infrastructure and simulated diverse policy measures including market integration and government initiative in investment for experimenting their effectiveness. The most counterintuitive result of our research is that the market integration policy will facilitate CATV networks at an early stage until the year 2010, but will result in a diminished market size in the long run. With the system dynamics approach, we can enhance our understanding of the complex policy systems and get valuable insights through learning by modeling and simulation.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.4
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• pp.28-35
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• 2004

Stimulated by novel phenomena observed in molecular aggregates, recent developments in engineering fields of microscopic scales are creating tremendous opportunities for future nanotechnology-based applications. Investigation in the field involves sub-nanosecond or sub-micrometer interactions between extremely small systems, but researches, to date in these physical extremes have been quite limited. Here, we shed light on some of nanoscale phenomena using molecular dynamics simulation: visualization of various phenomena of nanoscales and exploration of size-dependent mechanical properties.

• Korean System Dynamics Review
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• v.2 no.1
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• pp.93-112
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• 2001

Inter-Organizational Cooperation is the most common and important strategy in modern public and privet sectors managerial activities. In this paper the concepts of inter-organizational cooperation means not selfish cooperation as in the game circumstance and theory, but general collaborative action between organizations, they have share same goal. The achievement level of jointed-goal of inter-organization is depended upon the performance of cooperation, which resulted from the conditions and circumstances of cooperation. This paper analyses the effect of inter-organizational cooperation on achievement level of the jointed goal between two organizations with computer simulation model of the system dynamics approach. In the computer simulation model, three factors, goal perception, communication, and control, are considered as a key conditions of cooperation, which impact on the performance of cooperation. Simulation model was constructed with focus on the dynamic interactions between these three factors and the achievement level of jointed-goal. Consequently, the results found in this paper may provide further grounds for reducing the time delay that included in the conditions of cooperation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.41-55
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• 2015

This study is proposed a new hybrid mount having a moving-magnet type electromagnetic actuator to reduce the vibration transmitted from naval shipboard equipment to the structure of the ship's hull. Optimal design specifications are determined through experimental analysis. The detailed design of the hybrid mount is determined through several design steps with electromagnetic numerical analysis using Maxwell Software(S/W). The hybrid mount that combines a rubber mount and an electromagnetic actuator has a fail-safe function for shock resistance. The mount is fabricated and tested using a universal testing machine to evaluate the design specifications. Finally, numerical simulation of the hybrid mount is performed to confirm control performance and applicability.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.195-204
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• 2014

The transition from fossil to renewable energy is inevitable due to fossil depletion. So, Renewable energy is very important for energy security and economic growth although it's R&D is long-term and high risky project. We propose new valuation method which combined system dynamics and compound real option method for long-term and high risk projects such as renewable energy. This method can show dynamic valuation results for the complex causal interaction and be easy for Monte-Carlo simulation to estimate volatility. And it can reflect the value of flexible decision for uncertainty. We applied the empirical analysis for Korea's photovoltaic industry by using this method. As results by empirical analysis, photovoltaic's R&D has high valuation using this method compared by traditional valuation methods such as DCF.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.1
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• pp.88-94
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• 2008

In this paper, a design method of a missile guidance command is presented considering the dynamics of missile control systems. The design of a new guidance command is based on the well-known PNG(propotional navigation guidance) laws. The missile control system dynamics cause the time-delays of the PN guidance command and degrade the performance of original guidance laws which are designed under the assumption of the ideal missile control systems. Using a backstepping method, these time-delay effects can be compensated. In order to implement the guidance command developed by the backstepping procedure, it is required to measure or calculate the successive time-derivatives of the original guidance command, PNG and other kinematic variables such as the relative distance. Instead of directly using the measurements of these variables and their successive derivatives, a simple disturbance observer technique is employed to estimate a guidance command described by them. Using Lyapunov method, the performance of a newly developed guidance command is analyzed against a target maneuvering with a bounded and time-varying acceleration.