• Journal of the Korean Society for Railway
• /
• v.15 no.1
• /
• pp.1-8
• /
• 2012

Wheelset dynamic analysis is a key element to determine the degree of accuracy of railway vehicle dynamics. In this study, a three-dimensional wheelset dynamic analysis is presented in such a way that the precise wheel-rail contact analysis in three-dimension is implemented into the dynamic equations of a wheelset. A numerical procedure that can be used for the analysis of a wheelset dynamics when the wheel-rail two point contact occurs in a cornering maneuver is developed. Numerical solutions of the constraint equations and the dynamics equations of a wheelset are achieved by using Runge-Kutta method. The proposed wheelset dynamic analysis is validated by comparison against results obtained from VI-RAIL analysis.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.18-24
• /
• 2010

Conventional methods for railway vehicle dynamic analysis have mostly relied on the approximate method based on 2-dimensional contact analysis. Recently, 3-dimensional approaches to achieve an accurate solution for wheel-rail contact analysis have been proposed, but are not practical to apply to actual simulation due to time-consuming processes. The main focus of this study is to present a new method of railway vehicle dynamic analysis by calculating wheel-rail contact forces based on efficient 3-dimensional wheel-rail contact analysis. A 3-dimensional wheel-rail contact analysis and numerical analysis of wheelset dynamic equations will be presented.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.1851-1855
• /
• 2011

The accuracy of wheel-rail contact analysis is mainly determined by the methods to find wheel-rail contact points and to calculate contact forces. The 2-dimensional approach which calculates contact points based on the profile curves of the wheel and rail has advantage of reducing calculation time but shortage of approximating the solutions when comparing with 3-dimensional analysis In this analysis, wheelset dynamic behaviors calculated by the approach based on the 2-dimensional wheel-rail curves are compared with those by the 3-dimensional wheel-rail surfaces. Yaw angle and lateral displacement of wheelset center are compared when negotiating a curve.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2014.06a
• /
• pp.109-111
• /
• 2014

본 논문에서는 비접촉 동작 인식 기기를 활용한 동영상 콘텐츠 검색 시스템을 소개한다. 제안하는 시스템은 스마트 TV와 같은 인터넷이 가능한 디스플레이의 동영상 콘텐츠를 대상으로 하며, 콘텐츠 자체 또는 콘텐츠 내의 객체에 대한 정보를 검색 결과로 제공한다. 시스템 구현에 앞서 영상 콘텐츠의 검색 요구 사항에 따라 시나리오 및 기능을 수립하고, 각각의 기능은 비접촉 동작 인식 기기인 립모션을 기반으로 손 동작을 지정하였다. 따라서, 제안하는 시스템은 사용자의 손가락 동작에 의해 선택된 영역을 모바일 비주얼 검색 서버에 전송하게 되고, 검색 결과는 모바일 기기를 통해 최종적으로 전달된다. 본 논문에서는 시스템을 실제로 구현하고 다양한 콘텐츠에 대하여 실험하였다. 개발된 시스템을 통해서 사용자는 손을 이용한 간단한 동작에 의해 콘텐츠 정보, 콘텐츠 내 객체의 정보를 실시간으로 모바일을 통해 제공받을 수 있다.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.714-717
• /
• 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 Precision Engineering
• /
• v.16 no.6
• /
• pp.148-159
• /
• 1999

A numerical method is presented for the dynamic analysis of spur gears rotating with very high angular speeds. For an efficient computation each gear is assumed to consist of a rotating rigid disk and an elastic tooth having mass, and finite element formulations are used for the equations of motion of the tooth. The geometric constraint is imposed between the rigid disk and the elastic tooth to fix them, and contact condition is imposed between the meshing teeth of the gears. At each iteration of each time step the Lagrange multiplier and contact force are revised by using the constraint error vector, and then the whole equations of motion are time integrated with the given Lagrange multiplier and contact force. For the accurate solution the velocity and acceleration constraints as well as the displacement constraint are satisfied by the monotone reductions of the constraint error vectors. Computing procedures associated with the iterative schemes are explained and numerical simulations are conducted with the spur gears.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.5
• /
• pp.375-380
• /
• 2012

In this study, dynamic load and dynamic contact force between a building block and wire ropes of a goliath crane are calculated during lifting or turn-over of a building block for the design of an optimal lug arrangement system. In addition, a multibody dynamics kernel for implementing the system were developed. In the multibody dynamics kernel, the equations of motion are constructed using recursive formulation. To evaluate the applicability of the developed kernels, the interferences and dynamic contact force between the building block and wire ropes were calculated and then the hull structural analysis for the block was performed using the calculation result.

• Journal of the Korean Society for Railway
• /
• v.13 no.1
• /
• pp.16-22
• /
• 2010

Various programs for dynamic simulation of the railway vehicle have advantages and disadvantages. These programs have limitation that cannot express a large deformable body for an wire of the railway vehicle. In this study, a program for dynamic simulation of the railway vehicle is developed. And the rigid, flexible and large deformable body can be simulated using this program. Its reliability is verified by comparison with a commercial program. Also, a wire is considered as the large deformable body and a sliding joint which connects the rigid body to the large deformable body is included. Moreover, as the wheel-rail contact module is added, the dynamic simulation of the railway vehicle can be analyzed using the developed program.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1998.10a
• /
• pp.151-159
• /
• 1998

디젤 엔진의 푸쉬로드 타입의 밸브 트레인에서의 힘의 전달 과정을 기구학적 응용을 통하여 구하였다. 이러한 힘의 최종 전달 단계인 캠과 평판 종동물의 접촉에서의 작용하중과 상대 운동 속도를 계산하였고 접촉면에서의 유막 두께를 고체면의 탄성변형을 고려하여 계산하였다. 특히 탄성 유체 윤활의 해석을 하는데 있어서 안정성과 수렴성이 우수한 멀티그리드 멀티레벨 기법을 사용하였으며 동하중 상태를 고려하여 유막 두께를 계산하고 기존의 정상상태의 해석해와 비교하였다.

• Journal of the Korean Society for Railway
• /
• v.2 no.3
• /
• pp.1-8
• /
• 1999

In this paper, descibed was the derived algorithm for calculating contact point between wheel and rail and the developed method for rail modeling. The proposed methods use travelling distance to represent rail center line position vector and rail orientation with respect to Newtonian reference frame. The methods call be easily used ill multibody dynamic analysis. Two numerical examples are shown to verify the validity of the proposed methods.