• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.20-27
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• 2007

Generally, the TFT-LCD image signal have nonuniform brightness and are composed of largely varying background signal, noise signal and abruptly changing Mura signal within Mura region. In this paper, Mura region enhancing algorithms using the proposed modified-MTF, which describes how human-visual-system's sensitivity varies in frequency domain, is proposed. The validity of the proposed algorithm was demonstrated ideal 1-dimensional signal and also then it was also tested TFT-LCD image. By the experimental results, the proposed algorithm is very effective in TFT-LCD image Mura enhancement.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.371-376
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• 2006

Recently the container volume in the global trade is steadily increasing. In an effort to cope with this trend, major ports of the world are stepping up the introduction of high-tech equipments, trying to establish a highly efficient information system, and improving the internal work processes of their container terminals. For speedy and effective cargo handling, they are making every effort in the diverse fields. The purpose of this study aims at developing an intelligent multi-agent system for the gate work of a container terminal, which is the place of authority transfer in a container terminal. The agent system suggested in this study has made a comparison between COPINO information by TOS (Terminal Operating System) and information on containers and trucks recognized at the gate passage, checking up their efficiency, and performing the function of controlling outside truck's input-output. Also, based on the records of outside truck's gate passage, some gates can be operated flexibly, consequently enhancing the efficiency of the gate function. The results of job performance will immediately be notified to the customers and terminal managers, thus helping them make decisions speedily.

• IE interfaces
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• v.11 no.2
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• pp.211-225
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• 1998

As mentioned in Part I all groupware products have been categorized into three areas which include cooperation/document management systems(CMS), collaborative writing systems(CWS), and decision-making/meeting system(DMS). This study deals with a comparative analysis of the last two areas, which is added to the first. It turns out that DMS has a higher market share than CWS. However. since effective collaboration requires the functions inherent to these two systems. they should be integrated somehow. The systems' functions that have been implemented in response to design issues have been described. Each group of the functions has been divided into three parts which consist of basic function, quasi-basic function. and others. Such a decision has been made according to the frequency rate of the functions provided in the products. While the basic functions in CWS include collaboraive writing beyond restriction of time and place, group awareness. version control. and others, in DMS realtime collaboration. brainstorming. presentation. various task support. policy formation. document management, multimedia, subgroup communication. topic commenter, categorizer, screen capture and various rile transfer. The basic functions are merged into the integrated functional model which was proposed in Part I. Since the model is so flexible that it can partially include the quasi-functions in addition to the hasic functions. a large number of products may stem from the modification of the functional model.

• Progress in Medical Physics
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• v.22 no.4
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• pp.163-171
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• 2011

The purpose of this study was to investigate the effect of various technical parameters for the dose optimization in pediatric chest radiological examinations by evaluating effective dose and effective detective quantum efficiency (eDQE) including the scatter radiation from the object, the blur caused by the focal spot, geometric magnification and detector characteristics. For the tube voltages ranging from 40 to 90 kVp in 10 kVp increments at the FDD of 100, 110, 120, 150, 180 cm, the eDQE was evaluated at the same effective dose. The results showed that the eDQE was largest at 60 kVp when compares the eDQE at different tube voltage. Especially, the eDQE was considerably higher without the use of an anti-scatter grid on equivalent effective dose. This indicates that the reducing the scatter radiation did not compensate for the loss of absorbed effective photons in the grid. When the grid is not used the eDQE increased with increasing FDD because of the greater effective modulation transfer function (eMTF). However, most of major hospitals in Korea employed a short FDD of 100 cm with an anti-scatter grid for the chest radiological examination of a 15 month old infant. As a result, the entrance surface air kerma (ESAK) values for the hospitals of this survey exceeded the Korean DRL (diagnostic reference level) of $100{\mu}Gy$. Therefore, appropriate technical parameters should be established to perform pediatric chest examinations on children of different ages. The results of this study may serve as a baseline to establish detailed reference level of pediatric dose for different ages.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.67-72
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• 2004

Many port states such as New Zealand, the USA, Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organism and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, they perceived that the ballast exchange in deep sea is the most effective method, together with submitting the ballast management plan which contains the effective exchange method, ballast system and safety consideration. In this study, we pursued both nautical engineering analysis and optimization of algorithm in order to generate the sequence of stability and rapidity. Heuristic Algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm, for automatic exchange of ballast water, by redefining core elements of the $A^\ast$ algorithm, such as node, operator and evaluation function. Final version of the optimized algorithm has been applied to existing bulk carrier and the performance of the algorithm has been verified successfully.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.317-333
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• 2007

The Round-Robin Test (RRT) for ground response analysis was performed by Division of Geotechnical Earthquake Engineering of Korean Geotechnical Society. This research analyzed the influence of analysis methods on variation of ground response by using the results of this RRT. The analysis methods include equivalent linear analysis, non-linear analysis and effective stress analysis. A total of 5 teams among 12 teams applied two kinds of analysis methods. This research compared the results of these 5 teams and analyzed the variation of the results according to analysis methods. The compared results were shear stress-shear strain relation, transfer function, time history and the response spectrum of ground surface acceleration, peak ground acceleration, peak shear strain and maximum excess pore pressure ratio.

• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.70-77
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• 2012

In this study, a numerical analysis of offshore installation using a floating crane with heave compensator is carried out in time domain. The motion analysis of crane vessels is based on floating body dynamics using convolution integral and the crane wire is treated as simple spring. The lifted structure is assumed as a rigid body with 3 degree-of-freedom translational motion. The heave compensator is numerically modelled by the generalized spring-damper system. Firstly, forced motion simulations of crane wire system are carried out to figure out the basic principle of heave compensator. The transfer function of crane wire system is obtained and effective wave period of heave compensator are found. Then, coupled analysis of crane vessel, crane wire, and lifted structure are performed in regular and irregular sea conditions. Two different crane vessels and two lifted structures (suction pile and manifold) are considered in this study. Through a series of numerical calculations, the effective zone of heave compensator is investigated with respect to wave period and crane wire length.

• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.65-70
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• 2004

Many port states, such as New Zealand, U.S.A., Australia, and Canada, have strict regulations to prevent arriving ships from discharging polluted ballast water that contains harmful aquatic organisms and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, ballast exchange in deep sea is perceived as the most effective method of emptying ballast water. The ballast management plan contains the effective exchange method, ballast system, and safety considerations. In this study, we pursued both nautical engineering analysis and optimization of the algorithm, in order to generate the sequence of stability and rapidity. A heuristic algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm for the automatic exchange of ballast water, by redefining core elements of the A$\ast$ algorithm, such as node, operator, and evaluation function. The final version of the optimized algorithm has been applied to existing bulk carrier, and the performance of the algorithm has been successfully verified.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.395-400
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• 2004

In most physical processes, the transfer function includes time-delay, and in the general distributed control system using computer network, there exists inherent time-delay caused by the spatial separation between controllers and actuators. This work deals with the synthesis of a discrete-time controller for a nonlinear system and proposes a new effective method to compensate the influence of input time-delay. The controller is synthesized by using input/output linearization. Under the circumstance that input time-delay exists, the system response has more overshoot and tends to diverge. For these reasons, the controller has to produce future input value that will be needed for the system. In order to calculate the future input value, some predictors are adopted. Using the discretization via Euler's method, numerical simulations about the Van der Pol system are performed to evaluate the performance of the proposed method.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.994-1000
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• 2011

In this study, the piezoelectric fan cooling system is investigated. In order to find the proper geometry and configuration, the numerical model for the flow field and heat transfer investigation is used. A simplified nonlinear deformation model is employed for transient solutions of a piezoelectric fan with the dynamic mesh and user defined function capability. The results show that the cooling is most effective when the length of a piezoelectric fan is 5 cm and the cooling plate is 3 cm. The results can be used to develop a new design method of heat sink for piezoelectric fans.