• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.74-79
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• 2004

The shape of cold rolled steel sheets is the degree of flatness, and the flatter, the better. Because undesirable strip shapes of cold rolled steel sheets can affect not only visible problem but also automatic working process in customer's lines, the requirement of the customers is more and more stringent. So we usually used the tension leveler to make high quality of strip flatness. For the improvement of the quality of strip flatness, this report developed three-dimensional FEM (Finite Element Method) simulation model, and analysis about the strain and stress distribution of strip in the tension leveling process.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.3-11
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• 1996

To investigate the effect of fatigue crack growth due to the surface residual stress, it is measured the residual stress distribution by x-ray diffraction at the crack tip each constant crack growth in the notch specimens, and quantitively assessed the effect of crack closure caused to the distribution of compressive stress at the crack tip from evaluating crack openning stress using the finite element analysis. It is concluded that the degree of the residual stress distribution at the crack tip is decreased with increasing the crack length. From the fact that it is similar to the crack openning stress ratio, it is found that the compressive residual stress distribution and size is related to the crack closure effect and surface residual stress field with propagating crack in the notch specimens depends on the stress intensity factor range at the crack tip.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.314-319
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• 2008

In this paper, the electric field distribution induced inside the brain during Transcranial Magnetic Stimulation(TMS) has been thoroughly investigated in terms of tissue heterogeneity and anisotropy as well as different head models. To achieve this, first, an elaborate head model consisting of seven major parts of the head has been built based on the Magnetic Resonance(MR) image data. Then the Finite Element Method(FEM) has been used to evaluate the electric field distribution under different head models or three different conductivity conditions when the head model has been exposed to a time varying magnetic field achieved by utilizing the Figure-Of-Eight(FOE) stimulation coil. The results show that the magnitude as well as the distribution of the induced field is significantly affected by the degree of geometrical asymmetry of head models and conductivity conditions with respect to the center of the FOE coil.

• IE interfaces
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• v.11 no.1
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• pp.23-32
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• 1998

This paper presents a model for assessing the efficiency of logistics activities in distribution centers. The DEA approach is adopted to compare the relative efficiency of distribution centers, where considered as input and output factors are warehouse floor area, field storage area, average inventory level, overhead costs, number of workers, number of orders, and total value of goods handled. The artificial neural network approach is also adopted to overcome the limitation of DEA. The 12 distribution centers of Korea Telecom are studied for the validation of the model, which results in 84.9% of learning accuracy. This model can be used to identify the inefficient factors in a distribution center and to reveal changes in the degree of efficiency over time.

• Communications for Statistical Applications and Methods
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• v.21 no.6
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• pp.501-512
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• 2014

Stylized facts on asset return are fat-tail, asymmetry, volatility clustering and structure changes. This paper simultaneously captures these characteristics by introducing a multi-regime models: Finite mixture distribution and regime switching GARCH model. Analyzing the daily KOSPI return from $4^{th}$ January 2000 to $30^{th}$ June 2014, we find that a two-component mixture of t distribution is a good candidate to describe the shape of the KOSPI return from unconditional and conditional perspectives. Empirical results suggest that the equality assumption on the shape parameter of t distribution yields better discrimination of heterogeneity component in return data. We report the strong regime-dependent characteristics in volatility dynamics with high persistence and asymmetry by employing a regime switching GJR-GARCH model with t innovation model. Compared to two sub-samples, Pre-Crisis (January 2003 ~ December 2007) and Post-Crisis (January 2010 ~ June 2014), we find that the degree of persistence in the Pre-Crisis is higher than in the Post-Crisis along with a strong asymmetry in the low-volatility (high-volatility) regime during the Pre-Crisis (Post-Crisis).

• Asian Journal of Turfgrass Science
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• v.10 no.3
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• pp.231-246
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• 1996

In order to elucidate the human impact on the distribution of cellular slime molds, samples were collected from 3 types of forest ; natural forests(Mt. Deogyu and Mt. Tsukuba), semi-natural forests(Seoul Great Zoo and Tama Zoo), artificial forests(Seoul National University and Tokyo Gakugei University) .The distribution of cellular slime molds in mountains was different from that of zoo and universities. In mountains, endemic species was occurred and species diversity was higher than in zoo and universities. In zoo and universities disturbed by human, Dictyostelium sphaerocephalum was occurred with higher importance value than in mountains. 6 species were selected to investigate the effect of temperature on froctification; Polysphondylium canlidum, D. delicatum. D. firmibasis, D. sphaerocephalum P. violaceum, D. purpureum. P. violaceum and D. purpureum had an optimum temperature for fructification around 25~3O˚C but the others around 22~23˚C. The degree of sensitivity to temperature was as follows; P. candidum >D. lelicatum > D. firmibasis > D. sphaerocephalum > P. violaceum > D. purpureum. Key words: Human impact, Cellular slime molds, Occurrence and distribution, fructification, Dictylostelium delicatum. Dictyostelium sphaerocephalum.

• Journal of Industrial Technology
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• v.25 no.A
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• pp.15-22
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• 2005

In order to evaluate seismic performance of multi-degree-of-freedom bridge structure, moderate lateral load distribution methods using the pushover analysis were developed by many researchers. One of important variables to improve an accuracy of pushover analysis is lateral load distribution. In this study, pushover analyses were performed using the five types of lateral load distribution and seismic performances were evaluated by capacity spectrum method (CSM). To verify an accuracy of suggested lateral load distribution, the maximum displacement estimates by the CSM were compared to those by inelastic time history analysis.

• Journal of Magnetics
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• v.22 no.2
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• pp.291-298
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• 2017

In this paper, the distribution of internal magnetic induction intensity of oil-film bearing twined solenoids was proposed. The magnetic field was generated by solenoids and magnetized bearing. The magnetized bearing was simplified as solenoid model. The mathematical model of magnetic induction intensity at any point of finite solenoid was deduced. Through experiment method, the distribution of the internal magnetic induction intensity of oil-film bearing and the magnetizing current formula of bearing was obtained. Further, the magnetic induction intensity distribution of magnetization bearing was solved successfully. The results showed that the magnetic induction was a second-degree parabola with open upwards along the axial plane and the distribution of magnetic induction intensity was opposite to the rule of magnetic induction intensity generated by solenoids. In addition, the magnetic flux density increased linearly with the increase of current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.959-964
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• 2007

To investigate the influence of partial discharge(PD) distribution characteristics due to various defects on the power cable joints interface, we used the K-means clustering method. As the result of PD number(n) distribution analyzing on $\Phi-n$ graph, the phase angle($\Phi$) of cluster centroid shifted to $0^{\circ}\;and\;180^{\circ}$ increasing with applying voltage. It was confirmed that the PD quantify(q) and euclidean distance of centroid were increased with applying voltage from the centroid distribution analyzing of $\Phi-q$ plane. The dispersion degree was increased with calculated standard deviation of the $\Phi-q$ cluster centroid. The PD number and mean value on $\Phi-q$ graph were some different by electric field concentration with defect types.

• Smart Structures and Systems
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• v.22 no.6
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• pp.699-709
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• 2018

With increasing traffic volumes and rising vehicle traffic, especially in cities, the number of pedestrian bridges has also increased significantly. Like all other structures, pedestrian bridges also suffer damage. In order to increase the safety of pedestrians, it is necessary to identify existing damage and to repair them to ensure the safety of the bridge structures. Owing to the shortcomings of local methods in identifying damage and in order to enhance the reliability of detection and identification of structural faults, signal methods have seen significant development in recent years. In this research, a new methodology, based on cone-shaped kernel distribution with a new damage index, has been used for damage detection in pedestrian truss bridges. To evaluate the proposed method, the numerical models of the Warren Type steel truss and the Arregar steel footbridge were used. Based on the results, the proposed method and damage index identified the damage and determined its location with a high degree of precision. Given the ease of use, the proposed method can be used to identify faults in pedestrian bridges.