• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.1-1
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• 2003

In this talk, a reduced-order modeling methodology based on centroidal Voronoi tessellations (CVT's)is introduced. CVT's are special Voronoi tessellations for which the generators of the Voronoi diagram are also the centers of mass (means) of the corresponding Voronoi cells. The discrete data sets, CVT's are closely related to the h-means clustering techniques. Even with the use of good mesh generators, discretization schemes, and solution algorithms, the computational simulation of complex, turbulent, or chaotic systems still remains a formidable endeavor. For example, typical finite element codes may require many thousands of degrees of freedom for the accurate simulation of fluid flows. The situation is even worse for optimization problems for which multiple solutions of the complex state system are usually required or in feedback control problems for which real-time solutions of the complex state system are needed. There hava been many studies devoted to the development, testing, and use of reduced-order models for complex systems such as unsteady fluid flows. The types of reduced-ordered models that we study are those attempt to determine accurate approximate solutions of a complex system using very few degrees of freedom. To do so, such models have to use basis functions that are in some way intimately connected to the problem being approximated. Once a very low-dimensional reduced basis has been determined, one can employ it to solve the complex system by applying, e.g., a Galerkin method. In general, reduced bases are globally supported so that the discrete systems are dense; however, if the reduced basis is of very low dimension, one does not care about the lack of sparsity in the discrete system. A discussion of reduced-ordering modeling for complex systems such as fluid flows is given to provide a context for the application of reduced-order bases. Then, detailed descriptions of CVT-based reduced-order bases and how they can be constructed of complex systems are given. Subsequently, some concrete incompressible flow examples are used to illustrate the construction and use of CVT-based reduced-order bases. The CVT-based reduced-order modeling methodology is shown to be effective for these examples and is also shown to be inexpensive to apply compared to other reduced-order methods.

• Journal of Agricultural Extension & Community Development
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• v.15 no.3
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• pp.461-497
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• 2008

The objective of the study was to evaluate the impact of the Call System of agricultural extension services in Korea. The respondents were satisfied on the speedy solution (74.5%), consultation (88.4%), and accessibility (79.7%) of the call system. However, satisfaction of farmers on in-depth consultation was higher (74.3%) than the satisfaction rated by the public servants of RDA (48.9%). Both groups replied positively (70.4%) on the need for expansion of the call system. The analyses of the results leads to a conclusion that there is a need to increase marketing on the importance of RDA's Call System to customers of agricultural extension and to improve accessibility through expansion of the system in other areas. These could solve the decreasing number of extension professionals and improve the quality and efficiency of extension services. These analyses may be useful as bases for a nationwide Call System that connects the center with other districts and for planning a renovation of information-oriented agricultural extension services. The issue that needs improvement is to abandon the grounds of agricultural technology information provider and respond to the customers' needs efficiently by building an established Call System which can minimize the side effect of the trends of reforming and downsizing the organization. It is needed to develop a unified management Call System of agricultural technology information that could provide real-time information, and database the results simultaneously for use as feedback to the Rural Development Programs. Related laws and policies need to be improved to establish a nationwide information network that maximizes the current network in agricultural regions to spread information, to provide institutional support, and to encourage development of training system and research and development by concerned institutes.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.497-501
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• 2009

'Digilog Book' integrates advantages of existing paper book and immersive digital contents in augmented reality environment, which enables users to feel physical touch and get additional multisensory feedback. As a high level authoring user interface, 'ARtalet' provides an intuitive way to make Digilog Book through 3D user interface in augmented reality environment. This paper mentions trajectory inserting and editing methods of 3D objects, then combining method of the trajectory. 3D object is selected by camera tracked prop, and then transformation matrix relative to book plane is stored in real time based on timeframe. The saved trajectory is managed as templates, and user can make various compositions of trajectories. We expect that suggested methods can enhance interest of readers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.126-131
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• 2004

As a noninvasive imaging method, optical coherence tomography system has been extensively studied because it has some advantages such as imaging of high resolution, low cost, and compact size configuration. In order to improve the SNR of OCT system, two types of interferometers were configured and then, we compared simulation with measurement of reference sample. In the OCT system is configured with Michelson interferometer, the contrast of cross-sectional image is reduced with low SNR detection which is due to loss of feedback interference signal from light source part. Also, in order to image measured data with real time, image processing program is constructed. From results of simulation, it is confirmed that improved Michelson interferometer is improved about 10[dB] with a 50 : 50 fiber coupler. And from the measurement of reference sample, about 5[dB] is improved with a 50 : 50 fiber coupler. It is confirmed that the OCT system is configured with the improved Michelson interferometer which has a good distinctive cross-sectional image due to higher contrast.

• Journal of Biomedical Engineering Research
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• v.29 no.4
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• pp.323-328
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• 2008

A patient with respiratory disorders such as a sleep apnea is increasing as the obese patient increase on the modern society. Positive Airway Pressure (PAP) devices are used in curing patient with respiratory disorders and turn out to be efficacious for patients of 75%. However, these devices are required for evaluating their performance to improve their performance by the mechanical breathing simulator. Recently, the mechanical breathing simulator was studied by the real time feedback control. However, the mechanical breathing simulator by an open loop control was specially required in order to analyze the effect of flow rate and pressure after operating the breathing auxiliary devices. Therefore the aims of this study were to make the mechanical breathing simulator by a piston motion and a valve function from the characteristic test of valve and motor, and to duplicate the flow rate and pressure profiles of some breathing patterns: normal and three disorder patterns. The mechanical simulator is composed cylinder, valve, ball screw and the motor. Also, the characteristic test of the motor and the valve were accomplished in order to define the relationship between the characteristics of simulator and the breathing profiles. Then, the flow rate and pressure profile of human breathing patterns were duplicated by the control of motor and valve. The result showed that the simulator reasonably duplicated the characteristics of human patterns: normal, obstructive sleep apnea (OSA), mild hypopnea with snore and mouth expiration patterns. However, we need to improve this simulator in detail and to validate this method for other patterns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1337-1345
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• 2012

The principle of Effective Based Operation applied to the Korean Theater resulted in measurable effects to win the minimum battle. Based on the finding, this study recommends the effect analysis methodology under the V-C interoperability system to acquire a weapon system. This method is followed as below; to confirm the effect data on the organized weapon system, to set MOE, MOP and effect considering the purpose of the analysis, to apply the appropriate operational concept and scenario on the weapon system, and then the available C Model is after action reviewed, adjusted, and given feedback. The V-C interoperability system enables to perform the real-time combat experiment under the virtual synthesized battlefield circumstances. The defensive battle organization and displacement of the future anti-tank guided weapon system was considered in the modeling process. Scenario was written, which encompasses company-level units and the battalion-level operation. Then the available AWAM was embodied and effect-analyzed, which formed the foundation of SBA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.273-279
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• 2016

This paper deals with a control system with a concentration sensor for Ni-W alloy plating solutions. The printed circuit board market has increased with the development of the electronics industry. Gold consumption has also increased dramatically. Various studies of composite plating solutions have been conducted because of the expense of gold. In comparison, the development of sensors capable of measuring a composite plating solution in real-time is still insufficient. Furthermore, there are few systems that can measure and control the concentration of the solution precisely. This study developed a sensor and system to control the concentration of composite plating solution accurately. The sensors were developed based on a spectrophotometric method and a feedback control method was applied in this system.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.64-67
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• 2006

Computer performance and the development of computer appliances of today have adopted a new shape of concept, "ubiquitous computing." Thus, users can readily obtain access to abundant information as they can utilize the wireless network taking advantage of the ubiquitous concept, which allows usage inhibited by neither time nor location. In this process, the supply and feedback of information tends to be made real in the form of "interactive agent". This interactive agent with the application of artificial intelligence can enhance the reliability of information using friendly characters, and is used as a tool to grasp the intention! and behavior patterns of the users. This paper will take a look at the concept and the definition of the intelligent agent with "added characteristic", and furthermore investigate the potential and the scope of its development analyzing its features and comparing the examples of the domestic market that pursues to generate profits with it.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.515-521
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• 2007

To increase the stevedore efficiency and service level at container terminal, it is essential to reduce working time of container crane which has a bottle neck in the logistic flow of container. The working speed and safety are required to be improved by controlling the movement of the trolley as quick as possible without big overshoot and any residual swing motion of container in the vicinity of target position. This paper presents optimal state feedback control using RCGAs in the case of existing constrained conditions

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.105-113
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• 2017

Network externality can be defined as the effect that one user of a good or service has on the value of that product to other people. When a network externality is present, the value of a product or service is dependent on the number of others using it. There exist asymmetries in network externalities between the online and traditional offline marketing channels. Technological capabilities such as interactivity and real-time communications enable the creation of virtual communities. These user communities generate significant direct as well as indirect network externalities by creating added value through user ratings, reviews and feedback, which contributes to eliminate consumers' concern for buying products without the experience of 'touch and feel'. The offline channel offers much less scope for such community building, and consequently, almost no possibility for the creation of network externality. In this study, we analyze the effect of network externality on the competition between online and conventional offline marketing channels using game theory. To do this, we first set up a two-period game model to represent the competition between online and offline marketing channels under network externalities. Numerical analysis of the Nash equilibrium solutions of the game showed that the pricing strategies of online and offline channels heavily depend not only on the strength of network externality but on the relative efficiency of online channel. When the relative efficiency of online channel is high, the online channel can greatly benefit by the network externality. On the other hand, if the relative efficiency of online channel is low, the online channel may not benefit at all by the network externality.