• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.05a
• /
• pp.267-271
• /
• 2002

Most studies of elsatohydrodynamic lubrication are oriented only to the measurement of film thickness itself with optical interferometer. In order to exactly investigate the characteristics of a certain lubricant, it is also important to get the information of traction force as well. In this work, we developed the device for measuring friction force of ehl contact condition together with the film thickness. To verify the validity of the measuring system, the friction force and film thickness under ehl condition are measured with the variation of additive ratios of viscosity index Improvers.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2019-2020
• /
• 2011

Electric Vehicle Supply Equipment(EVSE) is a system or an equipment to supply electric power for charging the traction batteries on the electric vehicle. Control Pilot is an electric signal generated by EVSE and is transmitted to the electric vehicle by a vehicle coupler and a contact. The duty cycle of control pilot determines the maximum current to be drawn by electric vehicle. When the duty cycle is 5%, it is indicated that digital communication is needed. This paper deals with the data format and definition about communication scheduling through the inband signal on the control pilot of EVSE.

• Proceedings of the KIEE Conference
• /
• 2007.10c
• /
• pp.211-213
• /
• 2007

Current of DC traction systems flows from the positive busbar of the substation, through the overhead contact system, to the vehicle, and returns through the running rails. Because the rails are not very effectively insulated from the earth a certain amount of current flows into the earth, especially in the area near the load and depots. At the place where the stray current leaves the rail and pipe, corrosion may take place. In this paper we introduce the electrolytic corrosion protection methods of depots using silicon rectifier for the rail.

• The Journal of Korea Robotics Society
• /
• v.4 no.4
• /
• pp.265-272
• /
• 2009

IVarious driving mechanisms to adapt to uneven environment have been developed for many urban search and rescue (USAR) missions. A tracked mechanism has been widely used to maintain the stability of robot's pose and to produce large traction force on uneven terrain in this research area. However, it has a drawback of low energy efficiency due to friction force when rotating. Moreover, single tracked mechanism can be in trouble when the body gets caught with high projections, so the track doesn't contact on the ground. A transformable tracked mechanism is proposed to solve these problems. The mechanism is designed with several articulations surrounded by tracks, used to generate an attack angle when the robot comes near obstacles. The stair climbing ability of proposed robot was analyzed since stairs are one of the most difficult obstacles in USAR mission. Stair climbing process is divided into four separate static analysis phases. Design parameters are optimized according to geometric limitations from the static analysis. The proposed mechanism was produced from optimized design parameters, and demonstrated in artificially constructed uneven environment and the actual stairway.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.9
• /
• pp.882-887
• /
• 2011

A spiral electrodynamic wheel is proposed as an actuator for the contactless conveyance of a conductive rod. When rotating the wheel around the rod, a radial force, a tangential force, and an axial force are generated on the rod and cause a screw motion of the rod. The rotation of the rod is the inevitable result due to traction torque of the wheel and the unintended motion to be excluded. However, the rotating speed of the rod should be measured without mechanical contact to be cancelled out through the controller, so the electrodynamic wheel is used as a sensor measuring the rotating speed of the rod indirectly as well as an actuator. In this paper, we model the magnetic forces by the proposed wheel theoretically and compare the derived model with simulation result by Maxwell, and analyze influences on the magnetic forces by key parameters constituting the wheel. The feasibility of the conveyance system is verified experimentally.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1996.10a
• /
• pp.210-217
• /
• 1996

Under strong shock loads including earthquake or blast, structures may start to crack in stress concentrated members. The continuous behavior of the structure changes to the discontinuous. In this study, numerical method analyzing continuous and discontinuous behavior of a structure is developed using a modified distinct element method. Equations of motion of each distinct element are integrated using the central difference method, one of the finite difference methods. Interactions between he elements are considered by an element and pore spring. The forces acting in the center of an element include contact stress transferred by element spring; tensile stress by pore spring; and external traction such as earthquake or blast load. To verify the proposed method, the behavior of the cantilever beam subject to the quasi-static concentrated force at the end is investigated. The failure behavior of the simply supported beam subject to the strong shock at the center is studied. The proposed method can predict the failure behavior of the structure due to the shock loading and the post-failure discontinuous behavior of the structure.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.942-946
• /
• 2010

As the major sources of interior noise of train at running condition are the wheel/rail contact noise, the traction motor's noise and the driving gear's noise and these noise sources are transmitted through the car body, the noises of HVAC and air duct can be ignored. But the interior noise of train at standstill condition is decided by HVAC's noise and noise from the diffuser through the air duct. the interior noise prediction of train at standstill condition should be performed considering the shape of air duct, the air velocity and noise reduction property inside the air duct. But it is hard to estimate the interior noise level by the numerical method. Therefore train maker predict the interior noise level using The commercial noise prediction program. This paper introduce the noise prediction method of the train at standstill condition using the commercial program appling the ray tracing method and statistical energy analysis.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.35-50
• /
• 2007

A contact patch between the wheel and the rail supports the train body and a traction power comes from it when rolling stocks run on the railroad. Friction force between the wheel and rail makes the train move on the rail. Whenever the train runs on the rail, the wheels and rails wear down by frictions inevitably. So it must be shaped by the lathe or changed for the safety train operation and the comfortable ride. Until now, many measures were carried out in order to prevent a wear and tear of the wheels. For example loop line railway in Kun Ja depot and Ji Chuk depot. This document reports the wheel changing data taken by maintenances department for the period before and after 1996 in the 1.2.3.4 lines in Seoul metro.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.6
• /
• pp.141-147
• /
• 1997

For the effective finite element analysis of the structures including material interfaces or contact surfaces, interface elements are proposed. Most of early works in this problem require not only iterative computation but also complex formulation because of the kinematic nonlinearities caused from the discontinuous behavior and the stress concentration phenomena. The proposed elements, however, are consistently formulated using relative displacements and tractions between top and bottom regular finite elements. The effectiveness of these elements are shown by solving various numerical sample problems including an leaf spring and comparing with results of general finite element analysis. As a result, more stable solutions are conveniently obtaines using interface elements than regular finite elements.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.59 no.3
• /
• pp.305-310
• /
• 2010

DC electricity feeder system operating in the urban railway is typically a feedback circuit consisted of the contact wire and electric railway vehicle via rail. But stray current is flowed on a structure that is not part of the intended electrical circuit with respect to a given structure. This paper presents comparison analysis of field test cases based on criteria of electrolytic corrosion protection of buried metallic structures adjacent to DC traction systems. As a result of it, we confirmed that measurement methods are different from each other about the same tests. Therefore measurement methods to prevent electrolytic corrosion need to establish electrical facilities standards to be applied domestic.