• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.2
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• pp.177-184
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• 1998

The equation of motion on the vehicle-bridge system is established as the simultaneous equations which are combined the equation of vehicle and bridge by the interaction elements. A vehicle element is modeled as lumped masses supported by springs and dashpots, and a bridge element with pavement roughness is modeled as beam elements. An interaction element is defined to consist of a bridge element and the suspension units of the vehicle resting on the element. By the dynamic condensation method, the degrees of the freedom are eliminated, and compared with all the degrees of freedom on the bridge, the efforts of calculation is decreased. Thus, although a very small computational error is occured, the present technique appears to be computationally more efficient. It is particularly suitable for the simulation of bridges with a series of vehicles moving on the deck.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.383-387
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• 2008

This paper analyzes the operation characteristics of a self excited induction generator with Steinmetz connection. For this analysis, the symmetrical components analysis is used to obtain the related expressions and the excitation capacitance and the magnetizing reactance are determined in turn by the condition of self excitation which includes the input impedance of the generator as viewed across load terminals. Two simultaneous equations of the condition of self excitation itself are solved by using the real and imaginary function in an application software. This method is applied to simulate the operation characteristics when the generator is driven at rated speed and the specified excitation capacitor is connected across the lagging phase. The results show that better operation characteristics except generated frequency are obtained by using relatively large excitation capacitance and resistive load.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1078-1082
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• 2001

An alternative formulation of the Helmholtz integral equation is derived to express the pressure field explicitly in terms of the velocity vector of a radiating surface. This formulation, derived for arbitrary sources, is similar in form to the Rayleigh's formula for planar sources. Because the pressure field is expressed explicitly as a surface integral of the particle velocity, which can be implemented numerically using standard Gaussian quadratures, there is no need to use Boundary element method to solve a set of simultaneous equations for the surface pressure at the discretized nodes. Furthermore the non-uniqueness problem inherent in methods based on Helmholtz integral equation is avoided. Validation of this formulation is demonstrated for some simple geometries.

• Journal for History of Mathematics
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• v.30 no.2
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• pp.101-119
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• 2017

This paper is a follow up study of [2]. In this paper we analyse the contents of middle school mathematics textbooks published in the 1st National Curriculum Period centered on the concept 'straight line' and discuss how they are different from contemporary mathematics textbooks in view of connectedness of contents, mathematical terms, textbook as a learning material vs. teaching material, relationship between contents of national curriculum and textbooks, and some topics related to direct proportion, function, method of equivalence as a method for solving simultaneous linear equations and so on. The results of our analysis and discussion suggest implications for reforming mathematics curriculum and developing mathematics textbooks.

• Structural Engineering and Mechanics
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• v.17 no.6
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• pp.829-862
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• 2004

This paper presents a method for the nonlinear analysis of beam elements subjected to the cyclical combined actions of torsion, biaxial flexure and axial forces based on an extension of the disturbed compression field (DSFM). The theoretical model is based on a hybrid formulation between the full rotation of the cracks model and the fixed direction of the cracking model. The described formulation, which treats cracked concrete as an orthotropic material, includes a new approach for the evaluation of the re-orientation of both the compression field and the deformation field by removing the restriction of their coincidence. A new equation of congruence permits evaluating the deformation of the middle line. The problem consists in the solution of coupled nonlinear simultaneous equations expressing equilibrium, congruence and the constitutive laws. The proposed method makes it possible to determine the deformations of the beam element according to the external stresses applied.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.571-576
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• 1996

The 3-stage cascade composed of the multisection-type bithermal $H_2$/$H_2O$-exchange columns was suggested for heavy water separation. In order to study the separation characteristics for the cascade, a matrix equation with 18 simultaneous equations was composed and the concentrations and flow rates were calculated for the all parts of the cascade. Product D-concentration decreases and extraction yield increases with increasing cut in each stage, which is one of the principal parameters of the separation characteristics. The optimization of the 3-stage cascade can be made by case study using the matrix equation.

• Communications for Statistical Applications and Methods
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• v.29 no.2
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• pp.151-160
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• 2022

The total system is composed of the main system (MS) and the failure detection equipment (FDE) which detects failures of MS. The analysis of system reliability is performed when the failure of FDE is possible. Several repair policies are considered to determine the order of repair of failed systems, which are sequential repair (SQ), priority repair (PR), independent repair (ID), and simultaneous repair (SM). The states of MS-FDE systems are represented by Markov models according to repair policies and the main purpose of this paper is to derive the system availabilities of the Markov models. Analytical solutions of the stationary equations are derived for the Markov models and the system availabilities are immediately determined using the stationary solutions. A simple illustrative example is discussed for the comparison of availability values of the repair policies considered in this paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.121-127
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• 1985

This paper deals with simultaneous geodetic networks adjustment by geographical coordinates(${\varphi}$, ${\lambda}$). The adjustment computation is performed by variation of coordinates, and the classical method with fixed points and free networks are also compared. Provisional values for observation equations are computed by extended Gauss-mid lattitude formula using existing official coordinates. Bessel ellipsoid and unit weight are adopted. The processing of a test-network by distances yields the average root mean square error of position 6.2 cm for classical method and 2.4cm for free networks. The standard error of unit weight in a test-network is $1.66{\times}10^{-6}$ radian (0.3"), and the analysis of error ellipses shows that free networks are more normally distributed errors.

• Journal of Technology Innovation
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• v.22 no.3
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• pp.261-286
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• 2014

Recently, project performance and management of government R&D program investing huge amount of budget is being focused. In this study, I built a model for estimating the performance creating paths of the government R&D program, then I analyzed the attributes of performances created by industries. I used simultaneous equations with FIML and examined the IT industry and CT industry of industrial technology innovation program using survey on R&D performance conducted by KEIT. On the analysis result, all the companies create the innovation performance through the government grants. However, the one who commercialize patents is SMEs in IT industry, and conglomerates in CT industry. SMEs in IT industry, which has characteristic of complex product, need extra self innovation activities even the government supports them. For improving the commercialization performance and technology development of SMEs in CT industry, it is effective when conducting cooperative research. These findings give us the implication that it is needed to consider different factors by industrial and enterprise characteristic when planning the public policy and government tasks.

• Journal of Korean Society of Forest Science
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• v.90 no.6
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• pp.742-746
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• 2001

This study was carried out to develop volume equations for Japanese Res Cedar(Cryptomeria japonica D. Don) trees which were widely planted from 1920s throughout the southern regions in south Korea. The 31 trees for stem analysis were selected in 6 different sites in the southern and 29 trees data were used for developing volume equation. The best equation in estimating Japanese Red Cedar trees's volume was suggested as $V=-0.002908+0.000125D^{1.907114}H^{0.645131}$. The simultaneous F-test for this equation revealed that the estimated individual tree volume was not significantly different (p=0.1936) from the observed tree volume for model evaluation. Therefore, this individual tree volume prediction equation could provide basic information for the construction of yield table and forest management.