• Wind and Structures
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• v.27 no.1
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• pp.29-40
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• 2018

To investigate the characteristics of the combined wind field produced by the natural wind field and the train-induced wind field on the bridge, the aerodynamic models of train and bridge are established and the overset mesh technology is applied to simulate the movement of high-speed train. Based on ten study cases with various crosswind velocities of 0~20 m/s and train speeds of 200~350 km/h, the distributions of combined wind velocities at monitoring points around the train and the pressure on the car-body surface are analyzed. Meanwhile, the difference between the train-induced wind fields calculated by static train model and moving train model is compared. The results show that under non-crosswind condition, the train-induced wind velocity increases with the train speed while decreases with the distance to the train. Under the crosswind, the combined wind velocity is mainly controlled by the crosswind, and slightly increases with the train speed. In the combined wind field, the peak pressure zone on the headstock surface moves from the nose area to the windward side with the increase of wind velocity. The moving train model ismore applicable in analyzing the train induced wind field.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.905-910
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• 2007

The cubicle of high speed train is the equipment where the important train- operating equipments are concentrated, so it requires the higher safety and reliability than any other equipment. Recently, the power car cubicle of KTX-II is, basically similar to that of KTX-I and HSR350x in its size, but consequently, as more sophisticated ATP/ATC and other parts are added, the order company points out the problem of rising temperature in summer. Especially, the interpretation about the possibility of guaranteeing the minimum freezing performance becomes necessary, when Fan Tray is out of order. This paper presents the method of improving the freezing performance while minimizing the effect of dust, and the method of guaranteeing the present freezing performance by the best arrangement of Fan Tray, when Fan Tray is out of order. And as a method of verifying this, we would like to predict the pressure, speed of a running fluid and temperature distribution of cubicle through the flow analysis.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.282-291
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• 2010

In line with current speed-up of railroad, a slab track has been increasingly adopted in a bid to secure the safety of track structure as well as to reduce the maintenance cost, and furthermore, the need for commercialization of domestically-developed swing-nose crossing turnout on slab track has been on the rise. For commercialization of swing-nose crossing turnout on slab which was developed in Korea, a technical and systematic performance evaluation system, considering local environment, shall be established and then the performance evaluation shall be accordingly implemented. This paper was intended to summarize the performance evaluation system, referring to the data available at home and abroad and the results of performance evaluation for domestically-developed swing-nose crossing turnout on slab track carried out to date based on that system. A performance evaluation system comprises the technical requirement appropriateness evaluation(component performance evaluation and design verification), laboratory test and on-site test. For domestically-developed swing-nose crossing turnout on slab track, appropriateness evaluation and laboratory test have been completed and the on-site test of those installed on the 2nd phase of Kyung-Bu HSR is underway now.

• Smart Structures and Systems
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• v.21 no.5
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• pp.537-548
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• 2018

A tunnel deformation monitoring system is developed with the use of fiber Bragg grating (FBG) sensing technique, aiming at providing continuous monitoring of railway tunnel deformation in the long term, and early warning for the rail service maintainers and authorities to avoid catastrophic consequences when significant deformation occurs. Specifically, a set of FBG bending gauges with the ability of angle measurement and temperature compensation is designed and manufactured for the purpose of online monitoring of tunnel deformation. An overall profile of lateral tunnel displacement along the longitudinal direction can be obtained by implementing an array of the FBG bending gauges interconnected by rigid rods, in conjunction with a proper algorithm. The devised system is verified in laboratory experiments with a test setup enabling to imitate various patterns of tunnel deformation before the implementation of this system in an in-service high-speed railway (HSR) tunnel.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.872-875
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• 2003

This paper introduces the propulsion system for Korean High Speed Railway(HSR). The developed propulsion system consists of PWM AC/DC converter and inverter. Compared with TGV-K, converters can improve input harmonics characteristics by the interlaced PW switching methods. And several merits such as unity power factor and simple regenerative operations can be also made. As a main power component, IGCT stack with suitable structure for high speed train and environmentally friendly cooling heat pipe is designed. In this paper, overall configuration of controller and control scheme is briefly described. Finally running tests are made to verify the developed propulsion system. The presented test results shows fast torque response, balanced converter current sharing, and appropriate running sequence.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.599-606
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• 2008

In this paper, the channel estimation performance of proposed TSC (TSC-S) is investigated in terms of the BER and BLER performances when HSR is considered for GERAN evolution system. The performance is evaluated by the link level simulation and is compared with the other TSC proposal (TSC-E). Numerical results show that the performance employing the TSC-S is almost same to that using the TSC-E. In the case of cochannel interferences, the similar tendency is shown, when joint least square is adopted for channel estimation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.2
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• pp.185-192
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• 2017

In this paper, we reviewed major design parameters for a solid type of deployable antenna and its structural design. We performed modal analysis for a single reflector panel made of aluminum and CFRP (carbon fiber reinforced plastic) to confirm the appropriateness of selected materials. We then predicted the elastic modulus of CFRP using the principles of unidirectional composite elasticity stiffness predictions such as the ROM (Rule of Mixture) and HSR (Hart Smith 10% Rule). To optimize the shape of the antenna reflector, a structural stiffness analysis was performed using derived numerical optimization factors. Six structural stiffness analyses were performed using the constructed experimental design method. The resulting optimal shape conditions are proposed to meet the structural stiffness requirements while minimizing weight.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.611-617
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• 2015

In the development of a vibration-based condition monitoring system in gearbox, one of the most important research topics is a quantitative analysis and test of the effect of gear damage on vibration of gearbox. This paper presents the evaluation result of vibration condition indicator according to the gear tooth damage through the vibration test of gearbox. The dynamic load test was performed with high speed railway (KTX)'s gearbox. The vibration of gearbox was measured according to a rotational speed change with the common gear fault modes, such as pitting and tooth breakage. The characteristics and the possibility of applying of vibration condition indicator on condition monitoring system were analyzed. As a result, the value of most condition indicator is gradually increased with the severity of gear faults. The NA6 indicator shows a low variation with the rotational speed change and high sensitivity in accordance with the gear fault.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1166-1171
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• 2008

Through Korean high speed train development project "G7 Leading Technology Development Project" from 1996 to 2002, HSR-350X has been developed. It can run the maximum operating speed of 350 km/h. Based on this technology, KTX-2 which will be served commercially has been developed till 2007. This paper introduces the aerodynamic analysis of the High-Speed EMU and shows the results of optimized aerodynamic nose shape design techniques and clean pantograph panhead original techniques study. These are the important parts of developments for high speed train which maximum speed is 400 km/h. Especially for decrease of tunnel micro pressure waves, the optimized nose area distributions were derived and the characteristics of micro pressure wave were analyzed. The robust optimized pantograph panhead shapes investigated to improve the performance and decrease the vortex flow which is thought to be its noise source. These shapes are clean and robust to external disturbances like unsteady accelerated flow or side wind was derived. Finally aerodynamic performances was verified with PIV and smog visualization by wind tunnel test.

• International Journal of Railway
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• v.6 no.4
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• pp.160-168
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• 2013

A spiral lattice girder-reinforced Bi-block sleeper which has enhanced durability against increasingly growing impact force and vibration by wheel load and improved structural performance while train runs at 350km/h high speed is hereby proposed. The section of a spiral lattice girder has stable and superior structural performance thanks to its confinement effect. To compare and analyze the structural performance of spiral lattice girder-reinforced bi-block sleeper, strain and stress distribution were evaluated after applying same load condition as existing triangular lattice girder-reinforced biblock sleeper, and to compare the structural performance of triangular lattice girder and spiral lattice girder, structural analysis of lattice girder was performed separately. As a result, a spiral lattice girder proved to have had superior structural characteristics to bi-block sleeper, and furthermore as a result of evaluating the fastener interface and constructibility with shape-improved lattice girder, no interference with existing railroad structure was found and in terms of cost efficiency, a spiral lattice girder appeared to be superior to existing lattice girder.