• Journal of KSNVE
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• v.10 no.1
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• pp.117-122
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• 2000

The dynamics of train has recently been analysed in many cases and very complex nonlinear creep theories have been developed by many engineers. But much calculation time is spent and latest complex creep theories cannot be adapted in train analysis. In this study efficient and fast train analysis method was suggested. Many of degree of freedom were reduced in multi-vehicle system using equivalent system and fast calculation time was achieved. And the accuracy of equivalent system method was proved by linear and nonlinear dynamic analysis.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.477-484
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• 2000

Earthquake response analyses are conducted for the investigation of the ground shaking during the 1995 Hyogoken-nambu earthquake. Port Island a man made island with about 8{{{{ KAPPA m^2 }} area is chosen for this purpose Because earthquake measurement with vertical array was conducted there. Strain dependent characteristics of soil can be modeled well into Hardin-Drnevich Model. Four analyses are conducted : total stress analysis by equivalent linear method non-linear method. and two effective stress analyses. All analyses except equivalent linear analysis show fairy good agreement with observed record mainly because the non-linear behavior of Holocene clay layer has predominant effect on the behavior of fill, However detailed investigation show that effective stress analyses give much better prediction than total stress analyses.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.138-144
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• 2000

The detent force caused by the interaction of magnets with the teeth of a armature core deteriorates the driving performance of a permanent magnet linear synchronous motor. In this paper, we analyze the fields and forces of a linear synchronous motor with segmented or skewed magnet arrangement according to lateral overhang length of permanent magnets. For the analysis, the 3-dimensional equivalent magnetic circuit network method is used. The detent force and the static thrust are analyzed according to the segmented or skewed angle and the overhang length of permanent magnets, and the optimal angles that the detent force is minimized are found out in each case. The analysis results are compared with the experimental ones and shown a reasonable agreement.

• Journal of the Chungcheong Mathematical Society
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• v.22 no.2
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• pp.281-286
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• 2009

In this paper, we introduce the notion of the complete fuzzy norm on a linear space. And we consider some relations between the fuzzy completeness and ordinary completeness on a linear space.

• Journal of the Chungcheong Mathematical Society
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• v.22 no.3
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• pp.597-606
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• 2009

In this paper, we introduce the notion of the statistically complete fuzzy norm on a linear space. And we consider some relations between the fuzzy statistical completeness and ordinary completeness on a linear space.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1013-1032
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• 2016

Several historical earthquakes demonstrated that local amplification and soil nonlinearity are responsible for the uneven damage pattern of the structures and lifelines. On April $25^{th}$ 2015 the Mw7.8 Gorkha earthquake stroke Nepal and neighboring countries, and caused extensive damages throughout Kathmandu valley. In this paper, comparative studies between equivalent-linear and nonlinear seismic site response analyses in five affected strategic locations are performed in order to relate the soil behavior with the observed structural damage. The acceleration response spectra and soil amplification are compared in both approaches and found that the nonlinear analysis better represented the observed damage scenario. Higher values of peak ground acceleration (PGA) and higher spectral acceleration have characterized the intense damage in three study sites and the lower values have also shown agreement with less to insignificant damages in the other two sites. In equivalent linear analysis PGA varies between 0.29 to 0.47 g, meanwhile in case of nonlinear analysis it ranges from 0.17 to 0.46 g. It is verified from both analyses that the PGA map provided by the USGS for the southern part of Kathmandu valley is not properly representative, in contrary of the northern part. Similarly, the peak spectral amplification in case of equivalent linear analysis is estimated to be varying between 2.3 to 3.8, however in case of nonlinear analysis, the variation is observed in between 8.9 to 18.2. Both the equivalent linear and nonlinear analysis have depicted the soil fundamental period as 0.4 and 0.5 sec for the studied locations and subsequent analysis for seismic demands are correlated.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.45-58
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• 2017

As many seismic codes for various facilities are changed into a performance based design code, demand for a reliable nonlinear response-history analysis (RHA) arises. However, the equivalent linear analysis has been used as a standard approach since 1970 in the field of site response analysis. So, the reliability of nonlinear RHA should be provided to be adopted in replace of equivalent linear analysis. In this paper, the reliability of nonlinear RHA is reviewed for a layered soil layer using Loma Prieta earthquake records in 1989. For this purpose, the appropriate way for selecting nonlinear soil models and the effect of base boundary condition for 3D analysis are evaluated. As a result, there is no significant differences between equivalent linear and nonlinear RHA. In case of 3D analysis, absorbing boundary condition should be applied at base to prevent rocking motion of the whole model.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.113-120
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• 2008

One-dimensional site response analysis is widely used to simulate the seismic site effects. The equivalent linear analysis, which is the most widely used type of site response analysis, is essentially a linear method. The method applies constant shear modulus and damping throughout the frequency range of the input motion, ignoring the dependence of the soil response on the loading frequency. A new type of equivalent linear analysis method that can simulate the frequency dependence of the soil behavior via frequency-strain curve was developed. Various forms of frequency-strain curves were proposed, and all curves were asserted to increase the accuracy of the solution. However, its validity has not been extensively proven and the effect of the shape of the frequency-strain curve is not known. This paper used two previously proposed frequency-strain curves and three additional curves developed in this study to evaluate the accuracy of the frequency-dependent equivalent linear method and the influence of the shape of the frequency-strain curves. In the evaluation, six recordings from three case histories were used. The results of the case study indicated that the shape of the frequency-strain curve has a dominant influence on the calculated response, and that the frequency dependent analysis can enhance the accuracy of the solution. However, a curve that results in the best match for all case histories did not exist and the optimum curve varied for each case. Since the optimum frequency-strain curve can not be defined, it is recommended that a suite of curves be used in the analysis.

• Structural Engineering and Mechanics
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• v.17 no.6
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• pp.751-766
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• 2004

This paper extends the use of the hierarchic degenerated shell element to geometric non-linear analysis of composite laminated skew plates by the p-version of the finite element method. For the geometric non-linear analysis, the total Lagrangian formulation is adopted with moderately large displacement and small strain being accounted for in the sense of von Karman hypothesis. The present model is based on equivalent-single layer laminate theory with the first order shear deformation including a shear correction factor of 5/6. The integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. A wide variety of linear and non-linear results obtained by the p-version finite element model are presented for the laminated skew plates as well as laminated square plates. A numerical analysis is made to illustrate the influence of the geometric non-linear effect on the transverse deflections and the stresses with respect to width/depth ratio (a/h), skew angle (${\beta}$), and stacking sequence of layers. The present results are in good agreement with the results in literatures.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.45-49
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• 1998

In this paper, the direct thrust control of PWM Inverter-fed Single-sided Linear Induction Motor (hereinafter referred to as "SLIM") is achieved with Space Vector control and PI control. The trembling of air gap length which is occured between the primary winding core and the secondaty structure of the SLIM must be minimized in order to get quick response characteristic. First, voltage equations of SLIM are shown on the suitable d-q axis equivalent circuits which analyze characteristics of the thrust and the normal force. Also, modeling and analysis of the d-q axis equivalent circuits are able to make robust transient thrust from the current regulation in the equivalent circuits. These results exemplified the direct drive of SLIM with the reference speed and thrust were verified by the experiments.periments.