• Journal of Korea Multimedia Society
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• v.4 no.3
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• pp.205-214
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• 2001

As the real time multimedia data service has become available due to the rapid progress of computer and Internet technology, the users can enjoy the newly developed service, which is called Video On-Dem-and(VOD). However, most of service providers have not paid their attention much on the software for various service modes on VOD, but they are only concentrating un the hardware to provide with the high resolution video display. Therefore, the service providers are recently to pay more attention on the software to cope with the various demands of users than hardware. So this paper has designed and implemented the VOD service system for those demands. Since the VOD service system suggested by this paper enable off-line search functions through E-mail, the users can possibly get the necessary information from off-line Search without connecting to the server while the current VOD service can prominently help users to save the time and effort to sea고 and select the Video contents by using periodical current awareness service supported by PUSH technology and user oriented information booking and feedback service supported by SDI service.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.182-189
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• 1999

In this paper, we present an ultrasonic sensor based path planning method using fuzzy logic for obstacle avoidance of an intelligent vehicle in unknown environments. Generally, Robot navigation in unknown terrains is a very complex task difficult to control because of the great amount of imprecise and ambiguous sensor information that has to be considered. In this case, fuzzy logic can satisfactorily deal with such information in quite efficient manner. In this study, we propose two fuzzy logic controller which is composed of steering controller and velocity controller respectively. Our object is to develop a fuzzy controller that can enable a mobile robot to navigate from a start point to a goal point without collisions, in the least possible travel time. The ability and effectiveness for the proposed algorithm will be demonstrated by simulation and expeiment.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.118-125
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• 2002

The previous kinematic analysis of wheeled mobile robots(WMRs) is performed in an ad-hoc manner, while those of the robot manipulators are done in a consistent way using the coordinate system assignment and the homogeneous transformation matrix. This paper shows why the method for the robot manipulators cannot be used directly to the WMRs and proposes the method for the WMRs, which contains modeling the wheel with the Sheth-Uicker notation and the homogeneous transformation. The proposed method enable us to model the velocity kinematics of the WMRs in a consistent way. As an implementation of the proposed method, the Jacobian matrices were obtained for conventional steered wheel and non-steered wheel respectively and the forward and inverse velocity kinematic solutions were calculated fur a tricycle typed WMR. We hope that our proposed method comes to hold an equivalent roles for WMRs, as that of the manipulators does for the robot manipulators.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.804-808
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• 2004

This paper deals with the designing of instrument for achieving surgical operation in the stomach and gullet using endoscope channel. The method used herein was to provide beads to knot suturing thread automatically. Following design rules were applied : 1) that instrument must be designed to enable surgical operator to stitch successively by only simple handling 2) that instrument must be designed to minimize insertion and extraction of endoscope. The main result from the experiment with animal stomach was that the surgical operation time was reduced and successive suture was available. Considering the requirement of operator‘s highly trained skills and the discomfort of patient in traditional suture process, the proposed design is expected to markedly improve the endoscopic suturing performance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.8 no.1
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• pp.53-59
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• 2002

A correctly designed bridge offers improved operational safety in terms of increased vigilance, flexibility of operation, precision of control and operator＇s situational awareness. According1y to design human centered bridge, the consideration shall be given to the man-machine interface, location and interrelation of workstation, configuration of console, windows. field of vision and bridge working environment. The state-of-the-art suits for one-man operation by integration of conning information and central information presentation. Further, it is desirable to enable two man ship operation for emergency operations, training purposes and redundancy. In this point of view, this thesis would like to design a conceptual bridge.

• Journal of the Korean Society of Safety
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• v.7 no.4
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• pp.23-32
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• 1992

Surface treatment and chemiluminescence characteristics of the polymer film. It was studied that the Intensities and rates of treatments are in proportional to condition of the treatment, considering the results of study on treatments to polymer film with discharge and ultraviolet irradiation through the methods such as surface resistance, contact angle, dyeing method, solace ten-sion and so on. It was also studied that the said has a nice correlation with the concerned result studied by chemiluminescence. Since the chemiluminescence will enable the Investigators to grasp a eertain condition caused by quitely slight deterioration with high sensitivity, it can be also used as a way for getting an information regarding the decision for degradation-condition and life-estimating of insulation material basically related to some security matters as well as surface condition of treatments through the above method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.4
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• pp.137-139
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• 2008

Floating zone, neutron transmutation-doped and magnetic Czochralski silicon crystals are being widely used for fabrication power devices. To improve the quality of these devices and to decrease their production cost, it is necessary to use large-diameter wafers with high and uniform resistivity. Recent developments in the crystal growth technology of Czochralski silicon have enable to produce Czochralski silicon wafers with sufficient resistivity and with well-controlled, suitable concentration of oxygen. In addition, using Czoehralski silicon for substrate materials may offer economical benefits, First, Czoehralski silicon wafers might be cheaper than standard floating zone silicon wafers, Second, Czoehralski wafers are available up to diameter of 300 mm. Thus, very large area devices could be manufactured, which would entail significant saving in the costs, In this work, the conventional Czochralski silicon crystals were grown with higher oxygen concentrations using high pure polysilicon crystals. The silicon wafers were annealed by several steps in order to obtain saturated oxygen precipitation. In those wafers high resistivity over $5,000{\Omega}$ cm is kept even after thermal donor formation annealing.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.26
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• pp.115-141
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• 2005

This study explores how strategic alliance activities are evolving and the factors that impact on the formation and development of airline alliances. Findings show the initiation of regional and more liberalized bilateral, or open skies, agreements have removed some of the impediments to structural changes in international aviation. Airlines in more liberal markets enter into greater numbers and more integrative forms of alliances. Also, airlines, on average, achieve better results of operation if the market is more liberal. Essentially, there is a positive relationship between the developments of alliances and the liberalization of air transport markets. It has been questioned that the US bilateral open skies agreements provide its carriers more access to the global market and countries that do not enter into such agreements with the US risk a loss of traffic. Consequently, open skies agreements may enable carriers who have the freedom to exercise market power to be dominant in the markets. This suggests that regulatory coordination and liberalization of international aviation reinforce each other and should therefore be pursued simultaneously.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.929-934
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• 2001

As the notion of environment protection changes throughout the world, construction engineers, as part of the effort to resolve environmental problems, have been actively doing research on environmental friendly porous concrete using large and non-uniform aggregate. Concrete having a great deal of continuous porosity enable water and air to pass freely through firmly hardened material, allowing necessary nutrients to reach roots of vegetation, thereby sustaining them. It is possible to prevent the exhaustion of natural resources by recycling waste concrete and industrial by-products, to reduce damage caused by the destruction of nature through effective management of natural resources, to preserve the natural environment and vegetation in urban areas by activating the soil, protecting the underground ecology system, and growing garden plants through the application of environmentally friendly concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.317-322
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• 2001

This paper investigates the influence of fine aggregates on bleeding of concrete. According to test results, as water content decreases, crushed sand content increases, fluidity shows decline tendency. As for aggregates kinds, concrete using sea sand shows most fluidity loss among the tested results. Compressive strength gains highly when crushed sand is used. As for bleeding of concrete, bleeding shows decline tendency because of increasing in powder content and filling effect of voids. Bleeding amount is in a decreasing order of magnitude for concretes made with the following aggregates: sea sand, river sand, and crushed sand. Accordingly, crushed sand mixed with river sand and sea sand with certain proportion enable to reduce bleeding and enhance strength.