• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.1089-1094
• /
• 1995

Methods for the measurement of copper(II) complexing capacity (CuCC) of natural waters by using the back-extraction of bis(benzoyl-trifluoroacetonate)copper(II) and the extraction rate of dithizonato-copper(II) complex were described. Experimental results show that the CuCC of the Kiryu river water samples from urban area were consistently larger than those from up-stream, due to a ligand which originated from human activities.

• Advances in nano research
• /
• v.14 no.5
• /
• pp.463-474
• /
• 2023

The purpose of this paper is to present the analysis of propagating and evanescent waves in functionally graded (FG) nanoplates with the consideration of nonlocal effect. The analytical integration nonlocal stress expansion Legendre polynomial method is proposed to obtain complete dispersion curves in the complex domain. Unlike the traditional Legendre polynomial method that expanded the displacement, the presented polynomial method avoids employing the relationship between local stress and nonlocal stress to construct boundary conditions. In addition, the analytical expressions of numerical integrations are presented to improve the computational efficiency. The nonlocal effect, inhomogeneity of medium and their interactions on wave propagation are studied. It is found that the nonlocal effect and inhomogeneity of medium reduce the frequency bandwidth of complex evanescent Lamb waves, and make complex evanescent Lamb waves have a higher phase velocity at low attenuation. The occurrence of intersections of propagating Lamb wave in the nonlocal homogeneous plate needs to satisfy a smaller Poisson's ratio condition than that in the classical elastic theory. In addition, the inhomogeneity of medium enhances the nonlocal effect. The conclusions obtained can be applied to the design and dynamic response evaluation of composite nanostructures.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.11 s.242
• /
• pp.1527-1533
• /
• 2005

Three methods for design sensitivity analysis such as finite difference method(FDM), direct differentiation method(DDM) and adjoint variable method(AVM) are well known. FDM and DDM for design sensitivity analysis cost too much when the number of design variables is too large. An AVM is required to compute adjoint variables from the simultaneous linear system equation, the so-called adjoint equation. Because the adjoint equation is independent of the number of design variables, an AVM is efficient for when number of design variables is too large. In this study, AVM has been extended to the eigenproblem of damped systems whose eigenvlaues and eigenvectors are complex numbers. Moreover, this method is implemented into a commercial finite element analysis program by means of the semi-analytical method to show applicability of the developed method into practical structural problems. The proposed_method is compared with FDM and verified its accuracy for analytical and practical cases.

• Structural Engineering and Mechanics
• /
• v.31 no.2
• /
• pp.137-152
• /
• 2009

Mechanic behavior of Y-shape thin-walled box girder bridge structure is complex, so one can not exactly hold the mechanical behavior of the Y-shape thin-walled box girder bridge structure through general calculation theory and analytical method. To hold the mechanical behavior better, based on elementary beam theory, by increasing the degree of freedom analytical method, taking account of restrained torsiondistortion angledistortion warp and shearing lag effect at the same time, authors obtain a thin-walled box beam analytical element of 10 degrees of freedom of every node, derive stiffness matrix of the element, and code a finite element procedure. In addition, authors combine the obtained procedure with spatial grillage analytical method, meanwhile, they build a new analytical method that is the spatial thin-walled box girder element grillage analysis method. In order to validate the precision of the obtained analysis method, authors analyze a type Y-shape thin-walled box girder bridge structure according to the elementary beam theory analytical method, the shell theory analytical method and the spatial thin-walled box girder element grillage analysis method respectively. At last, authors test a type Y-shape thin-walled box girder bridge structure. Comparisons of the results of theory analysis with the experimental text show that the spatial thin-walled box girder element grillage analysis method is simple and exact. The research results are helpful for the knowledge of the mechanics property of these Y-shape thin-walled box girder bridge structures.

• Journal of the Korean Wood Science and Technology
• /
• v.28 no.4
• /
• pp.72-82
• /
• 2000

Attempts were made to analyze the behavior of single and multiple-bolted connections through theoretical methods such as European yield theory, empirical approaching method, and semi-rigid theory instead of many experimental methods that have been actually inefficient and non-economical. In the case of a single-bolted connection, if accurate characteristic values of a material could be guaranteed, it would be more convenient and economical to perform the behavior analysis using a model based on the semi-rigid theory, instead of the existing complex yield model, or the empirical formula which produces errors, giving different results from the actual ones. If the variables of equation determining the load and deformation could be appropriately controlled, the analytical method in conjunction with a semi-rigid theory could be effectively applied to obtain the desirably predicted value, considering that the appropriate solution could be derived through a simpler equation using a less difficult method compared to the existing yield model. It is concluded that analytical method with semi-rigid theory can be used in the behavior analysis of bolted connection because our developed method showed excellent analysis ability of behavior until number of bolt is two. Although our analytical method has the disadvantage that the number of bolt is limited to two, it is concluded that it has the advantage than numerical method which complicated and time-consuming.

• International Journal of Ocean System Engineering
• /
• v.2 no.3
• /
• pp.195-199
• /
• 2012

This paper reports a new analytical method to calculate the planar displacement of structures. The cross-sections were assumed to remain in plane and the deflection curve was evaluated using the curvature values geometrically, despite being solved with differential equations. The deflection curve was parameterized with the arc-length of the curvature values, and was taken as an assembly of chains of circular arcs. Fast and accurate solutions of complex deflections can be obtained easily. This paper includes a comparison of the nonlinear displacements of an elastic tapered cantilever beam with a uniform moment distribution among the proposed analytical method, numerical method of the theory and large deflection FEM solutions.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.933-935
• /
• 2001

This paper presents a calculating method for inductance of the Switched Reluctance Motor(SRM) for torque characteristics and driving by analytical model. The approaches for calculating inductance have taken vary from detailed finite element analysis(FEA) and Fitting method in magnetization curves using complex nonlinear magnetic circuit models. But those methods have not satisfactory approach for machine performance calculations, because of having a long time and remodeling for analyses, therefore thus an alternative approach is required. So it is suggested simply calculating method of the inductance based on designed data of machinery by analytical model in unaligned and aligned rotor. In order to prove the calculating, there are compare with analytical FEM, direct measurement, this method, and simulation. The compared result is shown to obtain good accuracy.

• Journal of the Korean Ceramic Society
• /
• v.31 no.8
• /
• pp.869-873
• /
• 1994

Electrical properties of each interfacial layers on semiconducting ceramics have been analized and evaluated by complex impedance resonance method as functions of ambient temperatures and applied voltages. From the analytical results, it can be observed that the interfacial layers in a semiconducting ceramics vary individually with the ambient temperature and then this influence the total properties. Also, it has been confirmed that the applied voltage on semiconducting ceramics affect mainly the electrode interface, and thus the resistance and capacitance decrease due to the variation of potential barrier layers.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.2
• /
• pp.246-250
• /
• 2007

The crude extract of kohlrabi (Brassica oleracea gongylodes) was prepared as a rich source of peroxidase and its enzymatic and specific activities in the presence of cross-linked polyvinylpyrrolidone as a stabilizer were determined. This extract was used to catalyze the oxidation of thiamine in the presence of hydrogen peroxide to thiochrome at pH 8.0. Thiochrome shows strong fluorescence at 436 nm with excitation at 370 nm. Based on the obtained results, a sensitive and simple spectrofluorimetric method was developed for the determination of thiamine. In the optimum conditions, the calibration graph was linear from 2 × 10-7 to 1 × 10-4 mol L-1, with a detection limit of 6.2 × 10-8 mol L-1. The relative standard deviation (RSD) was 1.2% for 5 × 10-6 mol L-1 thiamine. The method was successfully applied to the determination of thiamine in vitamin B1 and vitamin B complex tablets and vitamin B complex syrup.

• Earthquakes and Structures
• /
• v.15 no.3
• /
• pp.263-273
• /
• 2018

Operational modal analysis is being widely used in aerospace, mechanical and civil engineering. Common research fields include optimal design and rehabilitation under dynamic loads, structural health monitoring, modification and control of dynamic response and analytical model updating. In many practical cases, influence of noise contamination in the recorded data makes it difficult to identify the modal parameters accurately. In this paper, an improved frequency domain method called Enhanced Least Square Complex Frequency (eLSCF) is developed to extract modal parameters from noisy recorded data. The proposed method makes the use of pre-defined approximate mode shape vectors to refine the cross-power spectral density matrix and extract fundamental frequency for the mode of interest. The efficiency of the proposed method is illustrated using an example five story shear frame loaded by random excitation and different noise signals.