• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.823-829
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• 2010

Railway is facing a new era by the remarkable technology-intensive development of railways in the rolling stock and track, trains and infrastructure facilities. But the relevant provisions of the regulations for the various driving speed limit accept most of the past rules and it is desperately needed to realize the efficiency of the train operation. In addition, because the rules that drive too many treats of redundancy(the same information is duplicated in the other company policy provisions), they can cause confusion among employees, and also because of the contents of the detailed provisions dealing with almost same regulations, they can cause probable failure and big accident. In this study, the relevant provisions of the current rules are analyzed and overcome problems to improve efficiency and duplicated contents of relevant provisions to drive trains are merged. Also by reorganization of complex speed limits, we can understand easily when even the unusual situation and make a simple decision to prevent accidents. As a result, we can establish the system by doing subsequent actions quickly and accurately.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.383-384
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• 2014

This paper investigates the experimental and simulated time-varying magnetic field generation in a chlor-alkali manufacturing process. 19kA thyristor-based rectifier is modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. The mechanical structure of current carrying conductor is simplified as an infinite long busbar model and low frequency harmonic contents up to 65kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc busbar of rectifier infringing the limit of ICNIRP. Along with simulation analysis the experimental measurement of the time-varying magnetic field in ac input busbar, rectifier block, dc load and busbar are presented. The experimental test results partly confirm the simulation results.

• 기술혁신학회지
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• 제4권3호
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• pp.342-354
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• 2001

The appearance of on-demand business model of multimedia contents is one of the biggest changes in the broadband Internet which aims at the high-speed Internet users. Currently the interest in the webcasting service, a new converged service of the broadcasting and the telecommunications, has been increased. However the quality of service is not guaranteed due to the bottleneck problem in a middle-mile as the fundamental limit of the Internet, and has not been improved greatly due to the small-scaled operators of the webcasting services. This study suggests a new business model of the multi-channel satellite webcasting service based on the satellite multicasting and content delivery network, which guarantees the quality of service and channelizes the contents by the type or by the special purpose.

• International Journal of Contents
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• 제1권1호
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• pp.50-58
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• 2005

Generally, multidimensional data such as image and spatial data require large amount of storage space. There is a limit to store and manage those large amounts of data in single workstation. If we manage the data on parallel computing environment which is being actively researched these days, we can get highly improved performance. In this paper, we propose a parallel multidimensional index structure that exploits the parallelism of the parallel computing environment. The proposed index structure is nP(processor)-nxmD(disk) architecture which is the hybrid type of nP-nD and 1P-nD. Its node structure in-creases fan-out and reduces the height of an index. Also, a range search algorithm that maximizes I/O parallelism is devised, and it is applied to k-nearest neighbor queries. Through various experiments, it is shown that the proposed method outperforms other parallel index structures.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.421-425
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• 2001

Among the many parameters describing water quality, total nitrogen content(TN) is regarded as important one in relation to water quality management of the waterbodies for its role in eutrophication process. This study evaluated for accuracy, convenience and promptness of nitrogen analysis methods : (1)UV spectrophotometric method, (2)summation method, (3)cadmium reduction method. And, the detection limit of each method was calculated using EPA method. The UV spectrophotometric method after oxidation appears to be more convenient and accurate in determination of the TN contents than the summation method and cadmium reduction method. The summation method is necessary to separate determinations of the organic nitrogen, ammonia, nitrite, and nitrate. And, because summation method has many other methods for each contents, it can be detected for wide range of concentration.

• International Journal of Contents
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• 제12권1호
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• pp.65-69
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• 2016

Wireless communication chipsets have fixed transmission rate and communication distance. Although there are many kinds of chipsets with throughput and distance purpose, they cannot support various types of wireless applications. This paper provides theoretic research results in order to support various wireless applications requiring different throughput, delayed quality-of-service (QoS), and different communication distances by using a wireless communication chipset with fixed rate and transmission power. As a performance metric, the probability for a data frame that successfully receives at a desired receiver is adopted. Based on this probability, the average number of transmission in order to make a successful frame transmission is derived. Equations are utilized to analyze the performance of a single-hop with channel coding and a dual-hop without error correction matter transmission system. Our results revealed that single-hop transmission assisted by channel coding could extend its communication distance. However, communication range extending effect of the single-hop system was limited. Accordingly, dual-hop transmission is needed to overcome the communication distance limit of a chipset.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2007년 가을학술발표회
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• pp.502-513
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• 2007

This paper describes the rainfall-induced slope failures caused by infiltration due to prolonged rainfall. The emphasis was on quantifying the effect of fine-grained contents which are influencing on the infiltration rate in the wetting front of initially unsaturated slopes during rainfall. Suction tests by tensiometer were performed for five mixture specimens with varying fine-grained contents and then, numerical analyses for the stability of unsaturated slopes are carried out for different relative densities and mixture portions based on the soil water characteristic curves obtained by GCTS pressure plate. It is shown that the fines are highly influenced on wetting front suction of unsaturated soil slopes. Based on the results, it is found that until 15% fine content is the limit showing different wetting front suction, beyond which the wetting band depth do not affect considerably the stability of unsaturated slopes.

• 경영과정보연구
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• 제11권
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• pp.45-69
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• 2002

One of important technology that must improve compulsorily on information-oriented society stores, search and transmit cultural contents data of great quantity in heterogeneous environment. SAN appeared by solution to resolve the problem such as integration management of heterogeneous system data, effective practical use of storage, data transmission limit is happened from here. SAN is system that manage and shares data of large quantity efficiently attaching directly to high speed network such as Fiber Channel that storage system has been attached to server individually SAN became more complicated than existent storage environment although offer much advantage such as decrease of storage expense and flexibility of system configuration. This study argues management way could consider in such environment that understand complexity and component of networked storage system.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 추계 종합학술대회 논문집
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• pp.302-307
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• 2004

현재 무선 네트워크 환경에서 많이 사용되고 있는 PDA의 스토리지 장치의 한계를 극복하기 위해 iSCSI를 이용한 원격 스토리지 시스템이 필요하며, 계속 급증하고 있는 무선 환경에서의 보안 문제를 해결하기 위해 IPSec 적용이 필요하다. 본 논문 에서는 PDA 상에서 원격 스토리지 시스템을 사용하기 위한 iSCSI와 보안을 위한 IPSec를 각각 설계, 구현하고 실제 환경에서의 실험을 통해 성능을 알아본다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.7-11
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• 1996

The results of an experimental study on the mechanical properties of concrete utilizing crushed sand for construction materials are persented in this paper. As the results show, the workability, compressive strength and drying shrinkage were improved by propeer contents of replaced crushed sand. And the workability, compressive strength and drying shinkage were decreased by increasing very fine sand. Also, the suitable weight contents of replacing ratio of crushed sand in concrete using crushed sand were in range of about 30%. And the use of crushed sand containing very fine sand under the permitted limit by regulated KS F 2558 has not very much problems in concrete.