• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.71-75
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• 1999

In this paper, we present the 3DOF force-reflecting interface which allows to acquire force of object within a virtual environment. This system is composed of device, virtual environment model, and force-reflecting rendering algorithm. We design a 3 DOF force-reflecting device using the parallel linkage, torque shared by wire, and the controller of system applied by impedance control algorithm. The force-reflecting behaviour implemented as a function position is equivalent to controlling the mechanical impedance felt by the user. Especially how force should be supplied to user, we know using a God-Object algorithm. As we experiment a system implemented by the interface of 3D virtual object and 3DOF force-reflecting interface, we can feel a contact, non-contact of 3D virtual object surface and sensing of push button model.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.356-361
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• 2005

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

• Journal of Welding and Joining
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• v.15 no.3
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• pp.47-55
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• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.100-104
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• 2013

A superhydrophobic mesh is a unique structure that blocks water, while allowing gases, sound waves, and energy to pass through the holes in the mesh. This mesh is used in various devices, such as gas- and energy-permeable waterproof membranes for underwater sensors and electronic devices. However, it is difficult to fabricate micro- and nano-structures on three-dimensional surfaces, such as the cylindrical surface of a wire mesh. In this research, we successfully produced a superhydrophobic water-repellent mesh with a high contact angle (> $150^{\circ}$) for nanofibrous structures. Conducting polymer (CP) composite nanofibers were evenly coated on a stainless steel mesh surface, to create a superhydrophobic mesh with a pore size of $100{\mu}m$. The nanofiber structure could be controlled by the deposition time. As the deposition time increased, a high-density, hierarchical nanofiber structure was deposited on the mesh. The mesh surface was then coated with Teflon, to reduce the surface energy. The fabricated mesh had a static water contact angle of $163^{\circ}$, and a water-pressure resistance of 1.92 kPa.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.940-945
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• 2009

This paper presents the design method of low order controller for the active pantograph of electric train system. The pantograph is the most playa role to supply constant current to the train. The design objectives are to have good tracking performance about reference contact force despite the stiffness variation that is like sinusoidal function concerned in train speed or span length of contact wire. In this paper, we consider stiffness variation from external disturbance of active pantograph to simplify model equation, and propose simple second-order controller which is designed by Characteristic ratio assignment(CRA) control method. Finally, we verify time response appling to model equation of real system and frequency response about parameter uncertainty like stiffness variation. it is performed by Matlab version 6.5 and Matlab simulink simulation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.714-717
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• 2011

본 논문에서는 선체 블록의 운반 작업 중 발생하는 동적 하중 및 골리앗 크레인의 와이어로프와 선체블록 간의 동적 접촉력을 고려한 최적 러그 배치 시스템을 설계하고, 다물체계 동역학 커널과 외력 계산커널을 개발하였다. 다물체계 동역학 커널은 recursive formulation을 이용하여 운동 방정식을 구성하고, 외력 계산 커널은 비선형 유체정역학적 힘, 선형 유체동역학적 힘, 풍력, 계류력을 계산할 수 있다. 이를 이용해 블록에 작용하는 와이어로프와 블록 간의 간섭과 동적 접촉력을 계산하고, 그 결과를 이용하여 러그가 부착된 블록의 구조 해석을 수행하였다.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.232-238
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• 2004

The dynamic characteristics of the current collection process of the high-speed railway are investigated through signals acquired during a test run. The signals are obtained from accelerometers, load cells, and strain gauges attached to various positions of the pantograph, and they are processed in time-and frequency-domains to obtain the dynamic characteristics. The main natural frequency of the pantograph is found to be 8.5Hz. There also are components at low frequencies varying linearly with the train speed. The contact frequency components above 20Hz is attenuated as they pass through the secondary suspension. The main frequency component of the load cell signal is found to be related with the rolling motion of the panhead generated by the stagger in the catenary.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.550-557
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• 1999

Results of the dynamic simulation on KTX catenary and catenary-pantograph interface are presented. Simulation programs based on finite element and finite difference models of the catenary are developed, while the pantograph is modeled as a linear 3-degree-of-freedom system. The catenary motion dynamics are primarily determined by the transmission and reflection of the propagating disturbance wave at the hanger and span boundaries. On the other hand, the catenary-pantograph contact characteristics are primarily influenced by the movement of the pantograph across the hanger and span boundaries, the amount of damping present in the contact wire, and the resonant frequencies of the pantograph.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.174.3-174
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• 2001

Electric power collection is one of the most important factors for the high-speed trains' operation. For the stable current collection, the contact wire of a catenary and the panhead of a pantograph should maintain a constant contact each other. In this paper, the catenary was modeled as a spring with time-varying stiffness from the point of a pantograph moving along the catenary, and the pantograph was modeled as a 3-D.O.F. mass-spring-damper system. Using the adaptive control method, the desired control performance could be obtained with the modeling errors and the time varying parameters. Also the state estimator was used considering the difficulty of applying the sensors obtaining feedback signals. Simulations were accomplished in various ...

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.409-416
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• 2016

The contact force characteristic between the pantograph and the catenary wire represents the current collection quality of trains; it should be precisely controlled under international standard. Recently, a noise reduction cover has been installed around the pantograph of high speed trains. However, little study on the contact force by the pantograph cover has been conducted. In this study, the impact on the current collection performance of the pantograph cover was analyzed by dynamic contact force measurement using a next generation high speed train (HEMU-430X). As a result, it was confirmed that the attachment of a pantograph cover could lower the mean contact force by approximately 50N at 300km/h. In addition, the pure difference of the average contact force by the presence of pantograph cover, except for the static pressure, was measured and found to be up to 110N at 300km/h. It was also found that the standard deviation of the contact force of 3~5N could be changed by use of a pantograph cover.