• Proceedings of the KSR Conference
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• 1999.11a
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• pp.209-217
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• 1999

A catenary system should be designed to be an uniform elasticity over a span in order to maintain the lowest possible loss of contact between a pantograph and a contact wire. A elasticity disuniformity of a catenary can be regarded as a important design factor used for predicting the current collection performance for a catenary. There are a couple of formulas to calculate elasticity disuniformity of a catenary according to the literature survey, The effectiveness of these formulas is reviewed by performing catenary elasticity and loss of contact analysis for 5 different configurations of catenary systems using a beam element based FEM program, KRRI developed program, and the loss of contact by GASENDO, RTRI developed program, respective]y. The results reveals that these formulas are not suitable to predict the current collection performance for a catenary. Therefore, a new formula based on the standard deviation of the elasticity over a span is proposed in this study. The analysis results show that the new formula for an elasticity disuniformity of a catenary is very effective in predicting the current collection performance for a catenary.

• Journal of the Korean Society for Railway
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• v.3 no.3
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• pp.131-138
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• 2000

The design of current collection system of high speed train requires the fundamental understandings for the dynamic characteristics of catenary system and pantograph. The stiffness of catenary system of high speed train has the varying characteristics for the change of contact point with pantograph, since the supporting pole and hanger make the different boundary conditions for the up-down stiffness of a trolley wire. The variation of stiffness results in Mathiue equation, which characterizes the stability of the system. However, the two-term variation of the stiffness due to span length and hanger distance cannot be solved analytically. In this paper, the stiffness variations are calculated and the physical reasoning of linear model and one term Mathieu equation are reviewed. And the numerical analysis for the two-term variation of the stiffness is done for the several design parameters of pantograph.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.692-697
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• 2007

The current collection system, pantograph, is one of the important subsystems in electric train system, because of it's fatal function and role of supplying power to the train system. Generally, the function of current collection system is evaluated by loss of contact rate between pantograph and contact wire in catenary by measuring arcs, or by statistical method of evaluating minimum mean contact force. The Korean Tiling Train(TTX) has been manufactured by KRRI and Korean domestic companies and is preparing the trial running test of itself. In this paper, we introduce our successful achievement, measuring system and applied methods of dynamic characteristics for the tilting pantograph, developed of by our own technology.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.598-605
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• 2000

The design of a current collection system of high speed train requires the fundamental understandings fer the dynamic characteristics of a catenary system and pantograph. The stiffness of the catenary system of high speed train has the varying characteristics for the change of the contact point with a pantograph, since the supporting pole and hanger make the different boundary conditions for the updown stiffness of a trolley wire. The variation of stiffness results in Mathiue equation, which characterizes the stability of the system. However, the two terms variation of the stiffness due to span length and hanger distance cannot be solved analytically. In this paper, the stiffness variations are calculated, and the physical reasoning of linear model and one term Mathieu equation are reviewed. And the numerical analysis for the two term variation of the stiffness is done for the several design parameters of the pantograph.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.459-462
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• 2005

The KHST(Korean High Speed Train) which had been developed by through 'G7-R&D project' has succeeded trial running test up to 350km/h on the Kyoung-Bu High Speed Track in December 16th, 2004. In order to evaluate the function and characteristics of KHST, various experimental conditions have been considered and conducted. In this paper, measured current collection characteristics and dynamic behaviors of KHST's pantograph are analysed over 300 to 350km/h in running speed of KHST. A measuring system developed and installed on the KHST for measuring the performance and mechanical characteristics of the KHST's pantograph was used for this trial running test and eventually, we proofed that KHST has a remarkable and stable current collection characteristics as it had been designed.

• Journal of the Korea Society of Computer and Information
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• v.22 no.4
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• pp.25-32
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• 2017

Recently, the use of NAND flash memory is being increased as a secondary device to displace conventional magnetic disk. NAND flash memory, as one among non-volatile memories, has many advantages such as low power, high reliability, low access latency, and so on. However, NAND flash memory has disadvantages such as erase-before-write, unbalanced operation speed, and limited P/E cycles, unlike conventional magnetic disk. To solve these problems, NAND flash memory mainly adopted FTL (Flash Translation Layer). In particular, garbage collection technique in FTL tried to improve the system lifetime. However, previous garbage collection techniques have a sensitive property of the system lifetime according to write pattern. To solve this problem, we propose BSGC (Balanced Selection-based Garbage Collection) technique. BSGC efficiently selects a victim block using all intervals from the past information to the current information. In this work, SFL (Search First linked List), as the proposed block allocation policy, prolongs the system lifetime additionally. In our experiments, SFL and BSGC prolonged the system lifetime about 12.85% on average and reduced page migrations about 22.12% on average. Moreover, SFL and BSGC reduced the average response time of 16.88% on average.

• Journal of Korean Library and Information Science Society
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• v.45 no.1
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• pp.5-25
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• 2014

The goal of this study is to propose the plan for activating collection services of public library in Seoul. For this goal, author analyzed and compared the core infrastructure, collection services, and their correlation of public libraries in 16 local governments and evaluated environment and the current situation of collection service of public libraries in Seoul. Based on the these results, author suggested five plans or strategies for vitalizing the collection services of public libraries. All public libraries in Seoul must maximize the visibility of the new collections, supply the culture(life-long learning) programs based on library collections, expand the breadth of the collection service through library cooperation system, strengthen interlibrary loan by establishment of the collaborative repository, and raise the awareness of the citizens about the library and collections.

• Journal of the Korean Society for information Management
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• v.23 no.4 s.62
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• pp.17-39
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• 2006

Building institutional repositories is known as one of powerful methods for realizing the open access movement. The Korean Education and Research Information Service(KERIS) proposed to organize institutional repositories into a consortium, called 'dCollection (Digital Collection),' composed of 62 universities since 2003. The purpose of this study is to investigate the current state of 40 member universities of dCollection using the evaluation model including 4 categories and 39 indicators , and, based on the survey outcomes, to pinpoint the procedural or performance weak points of the dCollection systems in order to find its customized solutions focusing on the improvement of use and self-archiving rates.

• Journal of Technology Innovation
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• v.13 no.3
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• pp.131-151
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• 2005

Industrial Technology Development Program enables the recipient to set up technology infrastructure and to facilitate technology diffusion. In return, government charges royalty from the program recipient. However, the current royalty system is not in the effective form. This study analyzes the various aspects of royalty collection methods applied to the Industrial Technology Development Program and recommend the following: (1) employ the combination of fixed amount royalty and running royalty with predetermined portion of revenue generated, (2) adjust the royalty collection duration by applying product life cycle, and (3) devise new program to link extra-gain from royalty collection with commercialization and other means to increase the effectiveness of research and development activities.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.453-455
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• 1995

In electrostatic airclean filter, the collection efficiency defends on particle charge in the ionizer section. The effect of electrostatic airclean filter condition (deposition of dust, variation of corona discharge current) on corona discharge characteristics was well studied. However, it seems not to be studied on corona discharge characteristics of electrostatic airclean filter respect to contaminated electrode which is caused by practical use. In this paper, Long-term(60days) effects are studied experimentally by two methods. The one is ozone concentration, the other is collection efficiency. Generation of ozone level was increased but collection efficiency was slightly reduced in long-term used electrostatic airclean filter.