• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.241-246
• /
• 1997

Corrugation of railway track can be caused by the various dynamic behaviors of traveling wheels and track. In this paper, the coupled vibrations of traveling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibration, the track supported by the sleepers and the traveling wheels are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered between the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile on the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-mass system. It may be thought to a development of railway corrugation.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.7 no.3
• /
• pp.165-170
• /
• 2007

Recommendation systems provide users with proper services using context information being input from many sensors occasionally under ubiquitous computing environment. But in case there isn't sufficient context information for service recommendation in spite of much context information, there can be problems of resulting in inexact result. In addition, in the quantification step to use context information, there are problems of classifying context information inexactly because of using an absolute classification course. In this paper, we solved the problem of lack of necessary context information for service recommendation by using dynamic profile information. We also improved the problem of absolute classification by using a relative classification of context information in quantification step. As the result of experiments, expectation preference degree was improved by 7.5% as compared with collaborative filtering methods using an absolute quantification method where context information of P2P mobile agent is used.

• Ocean Systems Engineering
• /
• v.12 no.4
• /
• pp.385-402
• /
• 2022

This paper deals with the study of hydrodynamic pressure in reservoir adjacent to the concrete gravity dam subjected to dynamic excitation. Widely famous finite element method is used to discretize the reservoir domain for modelling purpose. Pressure is considered as nodal variable following Eulerian approach. A suitable nonreflecting boundary condition is applied at truncated face of reservoir to make the infinite reservoir to finite one for saving the computational cost. Thorough studies have been done on generation of hydrodynamic pressure in reservoir with variation of different geometrical properties. Velocity profile and hydrodynamic pressure are observed due to harmonic excitation for variation of inclination angle of dam reservoir interface. Effect of bottom slope angle and inclined length of reservoir bottom on hydrodynamic pressure coefficient of reservoir are also observed. There is significant increase in hydrodynamic pressure and distinct changes in velocity profile of reservoir are noticeable for change in inclination angle of dam reservoir interface. Change of bottom slope and inclined length of reservoir bottom are also governing factor for variation of hydrodynamic pressure in reservoir subjected to dynamic excitation.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.149-156
• /
• 1995

This paper presents the surface profile of machined workpiece in face milling operation. The roughness model of feed direction is considered the cutting condition, the profile and run-out of inserts. For the dynamic model the cutting system can be modeled as avibratory system. The dynamic model of surface roughness is considered the relative displacements between tool and work- piece which can be obtained from the cutting system. These model can predict various surface roughnesses. i.e. maximum and arithmetic mean surface ruughnesses. Therefore, the developed model can be used for the monitoring of surface roughness.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.6
• /
• pp.3821-3826
• /
• 2014

This paper proposes a methodology for developing the performance of a solenoid valve for vehicles based on the dynamic analysis model by an electromagnetic field. The high performance solenoid model with a low current and high thrust was induced through the shape optimal design of the yoke and plunger. To perform the dynamic analysis of the solenoid valve, the input current profile was analyzed. The speed and thrust information was analyzed by FEM with this current profile. The co-simulation method of the circuit model of control logic and electromagnetic model of the solenoid valve was also proposed to analyze the performance with several current patterns. Finally, the performance of the original model and optimal one was compared.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.11 s.176
• /
• pp.111-117
• /
• 2005

The vibration problems associated with gear coupled rotors have been the focus of much engineering work. These systems are complex and difficult to analyze in that they have the problems associated with conventional rotors plus those additional problems associated with the gear couplings. This paper examines the problems peculiar to the gear mesh. Because of the meshing action of gears, the elasticity of the gear teeth introduces time-varying stiffness coefficients into the governing equations of motion. This means that system response must be thought of in terms of Mathieu-type equations, where multiple-frequency response occur due to the periodic coefficients. The meshing action of the gears also couples the lateral and torsional gear motions. Gear errors, such as tooth profile and spacing errors, produce forces and torque that excite the system at multiple frequencies, some of which are much higher than shaft rotational speed. To investigate how to the time-varying stiffness in the gear teeth and the gear errors act one the dynamic response of the gear coupled rotors, a three-dimensional dynamic model with lateral-tortional oscillation is developed. The harmonic balance technique is employed to solve this mathieu-type problem.

• Journal of KIISE:Software and Applications
• /
• v.33 no.9
• /
• pp.802-809
• /
• 2006

J2ME mobile programs have been widely used as mobile devices like mobile phones become popular. Efficient use of resources in mobile programs is very important because mobile programs are executed in mobile environment with insufficient resources. Moreover, most J2ME programs are event-driven, so effective event handling is important for reliability and efficient use of resource. In this research, we develop a dynamic event analysis system, which can show event handling in real-time. In this system, users can trace only interesting events by selecting some options, and can get event profile after execution.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.7
• /
• pp.711-717
• /
• 2014

An accelerated ultrasonic fatigue test (UFT) was used for analyzing very high cycle fatigue (VHCF, $N_f$ > $10^7$) behaviors of a specimen with a test resonance of 20 kHz. Using the finite element method (FEM), the dynamic behaviors of the specimen was studied by calculating the stresses along its gauge portion, with displacement. The shape of gauge portion profile was assumed to be a hyperbolic according to the stress equation of the UFT. However, as the specimen used in the test had a circular arc profile, the FEM was used for studying the local stresses for two cases of the gauge profile. The results were compared with those obtain from the stress equation of the UFT. The dynamic behavior of the gauge portion could be understood for further comparison with the actual results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.7
• /
• pp.723-728
• /
• 2011

Since the performance of a vacuum circuit breaker (VCB) mainly depends on the spring operating mechanism, an analysis of the spring operating mechanism is required in order to improve the design of a VCB. In this study, the static stiffness of the spring was determined by using a material testing machine, and the test results were used to model the spring through computer simulation. The multi-body dynamic model of the spring was established by using the RecurDyn program. The dynamic model was verified by comparing the results of stem displacements and rotating angles of the brake shaft obtained from the simulation and from the experiments. After verification of the dynamic model of VCB, the cam profile of the VCB was optimized through multi-body dynamics simulation in order to improve the performance of the closing mechanism.

• The KIPS Transactions:PartC
• /
• v.13C no.4 s.107
• /
• pp.491-500
• /
• 2006

In this paper, the management architecture and the ubiquitous profile based on CC/PP for contents adaptation in the ubiquitous environment is designed. The components and the attributes of the ubiquitous profile are defined based on the services scenario of contents adaptation in the ubiquitous environment. The ubiquitous profile was applied to techniques such as standard vocabulary, CC/PP structure, RDF schema and RDF to use effectively in the ubiquitous environment during the design. Also we design and propose the another management architecture based on ideas such as the dynamic constitution method, the metadata constitution method using a repository and the management method of gateway on center for the effective management of the ubiquitous profile. The result of performance evaluation for the proposed management architecture is more effective compared with the previous management method of the profile. The proposed the ubiquitous profile and the management architecture has provided the foundation of the research for a user to adaptation contents services in the ubiquitous environment.