• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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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.

• 한국철도학회논문집
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• 제3권3호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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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.

• 한국컴퓨터정보학회논문지
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• 제22권4호
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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.

• 한국도서관정보학회지
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• 제45권1호
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• pp.5-25
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• 2014

본 연구의 목적은 도서관 자료서비스의 중요성에 입각하여 서울시 공공도서관의 자료서비스 활성화 방안을 제안하는데 있다. 이를 위하여 시도별 공공도서관의 핵심인프라, 자료서비스 및 프로그램의 이용실적, 그리고 핵심인프라 및 이용실적의 상관관계를 분석하여 서울시 공공도서관 자료서비스의 현주소를 평가하였다. 이러한 분석 및 평가결과를 바탕으로 서울시 공공도서관의 자료서비스를 활성화하기 위한 5가지 방안을 제시하였다. 서울시의 모든 공공도서관은 신착자료의 노출력(가시성)을 극대화하고, 장서기반의 문화(평생학습)프로그램을 제공하며, 도서관 협력시스템을 구축하여 외연을 확대하고, 공동보존서고를 건립하여 상호대차를 강화하며, 대중의 공공도서관 및 장서 인식도를 제고시켜야 한다.

• 정보관리학회지
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• 제23권4호
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• pp.17-39
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• 2006

기관 리포지토리는 오픈 액세스 운동을 실현할 수 있는 핵심적인 체제의 하나로 알려져 있다. 한국교육학술 정보원은 학술 정보 공유 공간으로 대학 기관 리포지토리 컨소시엄인 dCollection을 2003년에 구성하여 현재 62개의 국사립 대학들이 회원 대학으로 참가하고 있다. 본 연구의 목적은 2005년도에 구축된 dCollection 평가 모형을 조사 도구로 활용하여, 40개의 대학 기관 리포지토리의 운영 현황을 파악하고, 이러한 조사 결과를 기초로 하여 dCollection 자료의 등록률 및 이용율 향상에 초점을 맞춰 국내 기관 리포지토리의 발전 방안을 제안하여 효율적인 국가지식정보 유통체제의 인프라 구축을 목적으로 한다.

• 기술혁신연구
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• 제13권3호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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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.