• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1173-1177
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• 2004

The high investment is necessary for the new high speed lines. So the KRRI was interested in the possibility of upgrading the existing line in order to speed up the train in the conventional lines. The tilting train system has been developed because the reconstruction of railway for the cant compensation costs very high. The purpose of the tilting system is to compensate the centrifugal acceleration in order to reduce the lateral acceleration of the passenger at high speed on the curves.The pantograph of the tilting train is indispensable in order to supply the electrification equipments with power in safe. The dynamic interaction between the pantograph and the overhead catenary system causes the variation of the contact force and the contact force variation can cause contact losses, arcing and sparking. If the spark happens between the pantograph and the overhead catenary system, the EMI(electro magnetic interface) and noises may occur. After all, the quality of current collection is deteriorated. This paper deals with the active control of pantograph and presents the LQ-servo controller to reduce the contact force variation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1617-1622
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• 2004

Two-phase flow of liquid and gas through pipe lines are frequently encountered in nuclear power plant or industrial facility. Pressure waves which can be generated by a valve operation or any other cause in pipe lines propagate through the two-phase flow, often leading to severe noise and vibration problems or fatigue failure of pipe line system. It is of practical importance to predict the propagation characteristics of the pressure waves for the safety design for the pipe line. In the present study, a theoretical analysis is performed to understand the propagation characteristics of a weak shock wave in a bubbly flow. A wave equation is developed using a small perturbation method to analyze the weak shock wave through a bubbly flow with comparably low void fractions. It is known that the elasticity of pipe and void fraction significantly affect the propagation speed of shock wave, but the frequency of relaxation oscillation which is generated behind the shock wave is not strongly influenced by the elasticity of pipe. The present analytical results are in close agreement with existing experimental data.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.361-366
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• 2005

The high investment is necessary for the new high speed lines. So the KRRI has been interested in the possibility of upgrading the existing line in order to speed up the train in the conventional lines. The pantograph in train is indispensable in order to supply the electrification equipments with power in safe. The pantograph and the overhead wire form a dynamic coupled system and they affect each other through the contact force. Unfortunately, as the operational speed of a train increases, the vibration of the pantograph and the overhead wire also increases. This may lead to a zero contact force between the pantograph head and the overhead wire, which can results in the loss of contact, arching and abrasion. If the arching and spark happen between the pantograph and the overhead catenary system, the EMI(electro magnetic interface) and noises may occur. After all, the quality of current collection is deteriorated. This paper describes the dynamic response between the pantograph and catenary system by the numerical simulations and presents the LQ-servo controller to reduce the contact force variation

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2145-2157
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• 2018

Congestion Management (CM) is an attractive research area in the electrical power transmission with the power compensation abilities. Reconfiguration and the Flexible Alternating Current Transmission Systems (FACTS) devices utilization relieve the congestion in transmission lines. The lack of optimal power (real and reactive) usage with the better transfer capability and minimum cost is still challenging issue in the CM. The prediction of suitable place for the energy resources to control the power flow is the major requirement for power handling scenario. This paper proposes the novel optimization principle to select the best location for the energy resources to achieve the real-reactive power compensation. The parameters estimation and the selection of values with the best fitness through the Symmetrical Distance Travelling Optimization (SDTO) algorithm establishes the proper controlling of optimal power flow in the transmission lines. The modified fitness function formulation based on the bus parameters, index estimation correspond to the optimal reactive power usage enhances the power transfer capability with the minimum cost. The comparative analysis between the proposed method with the existing power management techniques regarding the parameters of power loss, cost value, load power and energy loss confirms the effectiveness of proposed work in the distributed renewable energy systems.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.3
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• pp.191-198
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• 2016

Traceability is essential in modern automotive manufacturing. Among existing technologies, RFID is the most promising choice for this purpose. However, due to the harsh conditions of production lines, especially in the paint shop, automobile OEMs would require expensive dedicated RFID tags and readers, which are incompatible with standard RFID technologies. Unlike the manufacturing industry, the logistics industry uses UHF label tags for track and trace, which provides high performance and a low price. Recently, this technology has improved to the extent that it can be used in harsh conditions such as on metal parts or in liquid. Herein, we assess the technical, operational, and economic feasibility of UHF label-tag technology for seamless end-toend traceability. Based on prototyping, lab/field tests, and cost-benefit analysis, we have proven that the single disposable UHF tags can successfully replace the problematic and expensive tags used in most domestic automobile OEMs today.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.2
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• pp.229-239
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• 1996

for shortening of running time on existing line, speed up railways feel strongly the necessity of it, for fully realizing a role of transportation system, for human life style is high. and increasing of time value. Especially curved lines zone have crucial effects on the speed of train, in case the shortening of running time, it is thought, speed up in curved lines zone, considering a character of route alignment in korea, we obtain saving time using lateral force index for safety running of train and comfortable ride of passengers. The results of this study show that all curved zone improvements for the shortening of the train running time more efficiently than extension of transition curve.

• Wind and Structures
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• v.18 no.5
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• pp.473-495
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• 2014

Localized wind events, in the form of tornadoes and downbursts, are the main cause of the large number of failure incidents of electrical transmission line structures worldwide. In this study, a numerical model has been developed to study the behaviour of self-supported transmission lines under various tornado events. The tornado wind fields used were based on a full three-dimensional computational fluid dynamics analysis that was developed in an earlier study. A three-dimensional finite element model of an existing self-supported transmission line was developed. The tornado velocity wind fields were then used to predict the forces applied to the modelled transmission line system. A comprehensive parametric study was performed in order to assess the effects of the location of the tornado relative to the transmission line under F2 and F4 tornado wind fields. The study was used to identify critical tornado configurations which can be used when designing transmission line systems. The results were used to assess the sensitivity of the members' axial forces to changes in the location of the tornado relative to the transmission line. The results were then used to explain the behaviour of the transmission line when subjected to the identified critical tornado configurations.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.91-96
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• 2015

GRP pipe (Glass-fiber Reinforced Plastic Pipe) lines making use of FRP (Fiber Reinforced Plastic) are generally thinner, lighter, and stronger than the existing concrete or steel pipe lines, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried GRP pipes with large diameter(2,400mm). The vertical and horizontal ring deflections are measured for 387 days. The short-term deflection measured by the field test is compared with the result predicted by the Iowa formula. In addition, the long-term ring deflection is predicted by using the procedure suggested in ASTM D 5365(ANNEX) in the range of 40 to 60 years of service life of the pipe based on the experimental results. From the study, it was found that the long-term vertical and horizontal ring deflection up to 60 years is less than the 5% ring deflection limitation.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3111-3122
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• 1997

Since the advent of an information era, the traffic of communication has been remarkably increasing and the information service has gradually become speedy and popular. With these trends, it is necessary to extend the utilization of existing twist pair cables for PSTN(Public Switched Telephone Network) to provide high speed data services for telephone subscribers, In this paper, we have studied on a structure of discrete multi-tone ADSL(Asymmetric Digital Subscriber Lines) system which can support high speed multimedia service using a twist pair cable, and analyzed the transmission performance by computer simulations.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1011-1017
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• 2009

In pursuit of the Trans-Korea Railway (TKR) project connecting the Korean peninsular by a rail link, it is critical that the two railway systems in ROK and DPRK are comparable in criteria and standards. Yet, there is substantial divergence of the construction criteria between the two sides, which hinders from conducting the TKR project as well as the railway modernization of DPRK. In this regard, study and comparison of the criteria are a prerequisite for mitigating the hinderance. This study investigated the laws and regulations relating to the railway technologies and construction and in particular conducted a comparative analysis of both railway systems with a focus on railway facilities such as track, structures, electric power and signaling. The results of this study will provide a useful information for the improvement of existing lines and the construction of new lines in DPRK.