• Proceedings of the KSME Conference
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• 2004.11a
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• pp.498-503
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• 2004

A fundamental function of court sport shoes has been considered as the protection of human feet from unexpected injuries. But, recently its role for improving the playing competency is being regarded as a more important function. In connection with this situation, intensive efforts are being world-widely forced on the development of court sport shoes proving the excellent playing competency, by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the shoes design based upon the reliable evaluation of shoes functional parts. This paper addresses the application of finite element method to the evaluation of landing impact force of court sport shoes. In order to reflect the coupling effect between leg and shoes accurately and effectively, we construct a fully coupled shoes-leg FEM model which does not rely on the independent experimental data any more. Through the numerical experiments, we assess the reliability of the coupled FEM model by comparing with the experimental results and investigate the landing impact characteristics of court sport shoes.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.538-550
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• 2012

This study suggests a general methodology which is designed for assessing RDOC behavior at the catchment scale by coupling properly a series of steam flow and water quality simulation models and actual monitoring data set. The modified TANK model in which a river routing function is incorporated to the conventional one is applied to simulate the long-term daily stream flow data, and the simulated stream flow data is combined with the 7-parameter log-linear model coupled to the minimum variance unbiased estimator to simulate the long-term daily water quality (BOD, COD and TOC) loads. Finally, the regression analysis between the usually monitored water quality data (BOD, COD and TOC) and RDOC is combined with the simulated water quality data to manifest the spatio-temporal variability of RDOC flux behavior at the Korean TMDL catchment scale.

• Journal of Wetlands Research
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• v.14 no.3
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• pp.353-363
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• 2012

In order to operate the hydraulic structures efficiently for reducing flood damage after 4 Major River Restoration Project, it is essential to obtain enough hydraulic information with certain reliability. A coupled modeling system, providing spatial hydraulic information, for multi-dimensional hydraulic models was developed to complement 1-D hydraulic modeling. Developed system can offers spatial and grid unit information as well as line and section unit information from 1-D modeling. It is considered that the coupled modeling system can be used to provide various kinds of hydraulic information for river management and treatment.

• Journal of KSNVE
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• v.11 no.1
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• pp.82-88
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• 2001

In a transmission or geared rotor system a coupled phenomenon of lateral and torsional vibrations may occur due to the gear meshing effect. Particularly, in high speed or low vibration and low noise applications of geared rotor systems a coupled rotordynamic analysis is required to precisely predict their dynamic characteristics. In this paper a generalized finite element model of a gear pair element is developed, which actively couples the lateral and torsional vibrations due to the gear meshing effect. In the modeling the generalized forces due to the transmission error. geometrical eccentricities. and unbalances in the gear system are also considered. Then. using the developed gear pair element model a coupled unforced rotordynamic analysis is performed with a prototype 800 RT turbo-chiller rotor-bearing system having a hull-pinion speed increasing gear. Results show that the torsional vibration characteristics experience some changes due to the gear meshing and lateral dynamic coupling effect, but that they have no adverse effect and the lateral ones have no practical changes in an operating speed range.

• Tribology and Lubricants
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• v.26 no.1
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• pp.31-36
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• 2010

The brake system is an important part of the automobile safety system. The disc brake system is divided into two parts: a rotating axi-symmetrical disc, and the stationary pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperatures during the braking process. The frictional heat source (the pads) is moving on the disc and the location is time-dependent. Our study applies a moving heat source, which is defined by the time and space variable on the frictional surface, in order to simulate the frictional heat behavior accurately during the braking process. The object of the present work is the determination of the temperature distribution and thermal stress in the solid disc by non-axisymmetric 3D modeling for repeated braking.

• Journal of the Korean Institute of Navigation
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• v.9 no.1
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• pp.95-109
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• 1985

It has been generally known that the chattering of an AC electromagnetic contactor due to the fluctuation of attracting force is the primary cause of its abrasion and noise. To reduce this chattering effect, an AC electromagnetic contactor is mostly fitted with a shading coil which works the role to make difference in phases of two distinct components of attracting force. The theoretical interpretation of an AC electromagnetic contactor with shading coil and the equation of its attracting force per unit wattage consumed have already been proposed, however, few explications so far have been made on the determination of optimal circuit constants of shading coil. In this paper, the auther constructs a circuit model of an AC electromagnetic contactor with shading coil which is based on the theoretical interpretation of shading coil examined to be valid by experiments under some assumptions, and defines the equation of attracting force without chattering per unit wattage consumed as a performance function for determining the optimal circuit constants of shading coil. And then, the optimal circuit constants maximizing the performance function are determined by means of computer simulation founded on the above circuit model and the characteristics of those circuit constants are examined with special attention to the coupling coefficient.

• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.135-140
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• 2004

Wear mechanisms may be briefly classified by mechanical, chemical and thermal wear. A plane strain finite element method is used with a new material stress and temperature fields to simulate orthogonal machining with continuous chip formation. Deformation of the workpiece material is healed as elastic-viscoplastic with isotropic strain hardening and the numerical solution accounts for coupling between plastic deformation and the temperature field, including treatment of temperature-dependent material properties. Effect of the uncertainty in the constitutive model on the distributions of strait stress and temperature around the shear zone are presented, and the model is validated by comparing average values of the predicted stress, strain, and temperature at the shear zone with experimental results.

• Earthquakes and Structures
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• v.15 no.3
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• pp.243-251
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• 2018

The dynamic responses of a rocking wall-moment frame (RWMF) with a post-tensioned cable are investigated. The nonlinear equations of motions are developed, which can be categorized as a single-degree-of-freedom (SDOF) model. The model is validated through comparison of the rocking response of the rigid rocking wall (RRW) and displacement of the moment frame (MF) against that obtained from Finite Element analysis when subjected ground motion excitation. A comprehensive parametric analysis is carried out to determine the seismic performance factors of the RWMF systems under near-fault trigonometric pulse excitation. The horizontal displacement of the RWMF system is compared with that of MF structures without RRW, revealing the damping effect of the RRW. Frame displacement spectra excited by trigonometric pulses and recorded earthquake ground motions are constructed. The effects of pulse type, mass ratio, frame stiffness, and wall slenderness variations on the displacement spectra are presented. The paper shows that the coupling with a RRW has mixed results on suppressing the maximum displacement response of the frame.

• Journal of the Korean Society for information Management
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• v.33 no.2
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• pp.103-133
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• 2016

The valuation of patented technology has been recently emphasized, and the patent citation is known as an important factor. This study performed a generalized linear model to find variables that effect the patent citation. We classified 13 variables as morphological, technological and conceptual factors and used them to find out effective variables in 14 medical devices classification. Through the empirical study, we found seven effective variables (assignee nationality, assignee character, the number of inventors, the number of application countries, the number of IPC, the number of references, the strength of bibliographic coupling). In order to apply to Korean industry, this study has significance that provides basic research to citation analysis model.

• Journal of Power Electronics
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• v.12 no.4
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• pp.615-622
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• 2012

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.