• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.631-638
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• 2006

This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property $T_1$ from stiffness skeleton curve and nonlinear pseudo acceleration $A_{1y}$ and/or ductility ratio $\mu$ from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.55-66
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• 2006

This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property $T_1$ from stiffness skeleton curve and nonlinear pseudo acceleration $A_{1y}/g$ and/or ductility ratio p from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method. The conclusions of this study are as follows; (1) Nonlinear direct spectrum method is considered as a practical method which is applicable to compute the structural initial elastic period and the yielding strength from stiffness skeleton owe and calculate the nonlinear maximum response of structure directly from nonlinear response spectrum. (2) The comparison of the analysis results from NDSM and NRHA showed that the average errors were less than 20% in about 3/4 of the analysis cases, and that the results obtained from NDSM turned out to be generally larger than those from NRHA.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.286-289
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• 2008

Mass of generator is one of the most important characteristic value especially direct drive type wind turbine. This paper introduce how to decease mass of generator rotor frame without declining generator performance. To obtain optimal design of rotor frame, sensitivity analysis using Taguchi method and RSM(response surface method) are have been performed.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.3
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• pp.27-35
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• 1998

Steel structures with added viscoelastic dampers are analysed to investigat their behavior under earthquake excitation. The direct integration method, which produces exact solution for the non-proportional or non-classical damping system, is used throughout the analysis. The results from modal strain energy method are also provided for comparison. Then a new analytical a, pp.oach, based on the rigid floor diaphragm assumption and matrix condensation technique, is introduced, and the results are compared with those obtained from direct integration method and modal strain energy method. The well known phenomenon, that the effectiveness of the viscoelastic dampers depends greatly on the location of the dampers, is once again confirmed in the analysis. It is also found that the modal strain energy method generaly underestimates the responses obtained from the direct integration method, especially when the dampers are placed in only a part of the building. The proposed method turns out to be very efficient with considerable saving in computation this and reasonably accurate considering the reduced degrees of freedom.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.04a
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• pp.37-44
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• 1993

There are a lot of linear dynamic analysis methods for complex structures. Each method has advantages and shortcomings. Method of dynamic analysis for complex structure is selected considering characteristics of dynamic loading, computer facility available number of degree of freedem and accuracy of results. It is a main point of view to get economical results rather then accurate ones for analysis of general complex structures, Mode superposition method and direct integration method are generally used. However, the characteristics of load is not considered in mode superpositon method, the personal computer cannot be used in direct integration methods. To over-come these shortcomings, the component mode method incorporating Ritz algorithm updated is proposed to solve economically dynamic behavior of the structures. The purpose of study is a formulation of algorithm, and computer programing suitable for dynamic analysis of the complex structure in personal computer environment.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.1
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• pp.1-7
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• 2009

To establish the Fourier-Transform Infra-Red spectrophotometry(FTIR) Direct-On-Filter(DOF) technique as a useful analytical method for quartz in respirable dust samples, an influence of the kaolinite should be corrected. Respirable dust, created in a dust chamber containing the standard material of quartz and kaolinite were collected using a cyclone equipped with a 25 mm, $0.8\;{\mu}m$ pore size DM filter as a collection medium. This study was designed to compare three methods of correction for kaolinite when quantifying the content of quartz, including the least square, the optimum choice and the spectral subtraction methods. The content of quartz in the respirable dust samples was overestimated by 6.2% when mixed with kaolinite(35.5% by weight). The content of quartz containing kaolinite(72.8% by weight) were overestimated by 32%. The spectral subtraction method underestimated the quartz content by 1.5%, while the other two correction methods, the optimum choice and the least square method, overestimated the quartz content by 1.9% to 6.4% and 0.04 to 1.1%, respectively. The results of this study are suggested that, when correcting for effects of kaolinite on quantitative analysis of quartz in respirable dust by FTIR direct-on-filter method, the least square method produce the most unbiased results be compared with those of other correction methods.

• Journal of the Korean Data and Information Science Society
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• v.22 no.1
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• pp.65-71
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• 2011

Path analysis is a useful method to find out direct or indirect effects between variables. Compared to regression analysis for studying the casual relationship, this method has a good advantage. In this study, I want to figure out direct or indirect relationships between golf skills and adjust average scores using path analysis. To analyze data, I applied AMOS in SPSS and collected data in 2010 PGA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.809-814
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• 2006

In this paper, the modified direct method employing beam transformation technique is proposed in order to efficiently calculate hydroelastic responses of floating structure. Since the proposed method expresses the displacements of three-dimensional structure with those of transformed beam which leads to small number of equations of motion, the method is numerically efficient compared to the conventional direct method. To verify the efficiency of the proposed method a 500 m-long floating structure under wave loads is considered in numerical example. Displacements, bending moments, torsion moments and shear forces are calculated and computing tine is examined. The results are also compared with those of the conventional direct method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.17-23
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• 2007

In this paper, the modified direct method employing beam transformation technique is proposed in order to efficiently calculate hydroelastic responses of floating structure. Since the proposed method expresses the displacements of three-dimensional structure with those of transformed beam which leads to small number of equations of motion, the method is numerically efficient compared to the conventional direct method. To verify the efficiency of the proposed method, a 500 m-long floating structure under wave loads is considered in numerical example. Displacements, bending moments, torsion moments and shear forces are calculated and computing time is examined. The results are also compared with those of the conventional direct method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.866-870
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• 2001

Measurement techniques for in-duct acoustic source parameters can be classified into the direct method and the load method, according to whether it utilizes an extra external source or not. It is reported that the load methods yield the negative source resistance and the purpose of this paper is to clarify that the time-varying nature of the source is the main cause of this physically implausible result. For this purpose, the direct and load methods for measuring the source characteristics of a simplified fluid machine are simulated using the time domain numerical analysis. In the numerical simulations, the method of characteristics is employed and the source characteristics are calculated from the resultant data. It is shown that the load method results in negative source resistance for some frequencies, whereas the direct method yields positive values for all frequencies considered. It is found that the result of load method is quite sensitive to the change of cylinder pressure or valve profile in contrast to the direct method.