• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.16-25
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• 1997

This paper shows the development of the high accuracy vehicle positioning algorithm using the differential technique in vehicle tracking systems form the existing vehicle position which is acquired from the global positioning system (GPS). The control center receives the satellite ephemerise data and pseudorange correction from the reference station, and vehicle position from the moving vehicle. The pseudorange is calculated with the satellite position and the vehicle position, and corrected by pseudorange correction. Using this corrected pseudorange and kalman filter, more improved vehicle positioning data were obtained.

• Journal of Ocean Engineering and Technology
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• v.11 no.1
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• pp.3-9
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• 1997

In this paper, design sensivity of plate natural frequency is computed for thickness design variables. Once the variational equation is derived from Lagrange quation using the virtual displacement, governing energy bilinear form is obtained and sensivity equation is formulated through the first variation. Natural frequency is obtained using the commercial FEM code and the accuracy of sensivity is verified by finite difference. The accuracy of natural frequency and sensivity improves for the fine mesh model.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.209-215
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• 2005

The dimensions and forms of precise machined parts are different to kinds of machine. It will be variant according to machine wear, tool form, cutting method and cutting condition at the same machine. At that time, the most important things are controlled and measured by appropriate measuring instruments. This paper aims to contribute to improving measurement accuracy through evaluation and consideration about various roundness in the machining company.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.12
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• pp.1582-1585
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• 1988

A cavity perturbation technique is employed to determine the dielectric property of thin samples. Substrates in microwave integrated circuits are fabricated in sheet form and are expected to have a dielectric constant less than 10 and a dielectric loss better than 10**-3. This research aimed to determine both dielectric constant and dielectric loss with good accuracy. The tecynique makes use of thin circular disk samples placed in a right circular cylindrical cavity. The accuracy of measurements is within \ulcorner% for dielectric constnat and 3x10**-4 for dielectric loss.

• Journal of the Korean Data and Information Science Society
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• v.19 no.2
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• pp.497-504
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• 2008

In this paper we studied the saddlepoint approximations to the distribution of quadratic forms in normal variables. We derived the approximations as a special case of Na & Kim (2005). Also applications to a statistic which concerns intraclass correlation coefficient are presented. Simulations show the accuracy and availability of the suggested approximations.

• ETRI Journal
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• v.11 no.4
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• pp.98-104
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• 1989

Closed form solution of nonlinear 2-DEG concentration formula is proposed. This allows us to model continuous 2-DEG charge concentration as the function of gate voltage covering subthreshold region of the I-V curves. Comparisons of the Ids-Vgs characteristics and transconductance with the measured data were performed to show the accuracy of the proposed model. This way we have completely closed form I-V characteristics in subthreshold, triode and saturation region incorporating accurate charge control mechanism for HEMTs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.7
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• pp.1-10
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• 1982

This paper derives the algorithm to estimate the operating cost, its marginal cost, and the reliability indices for the long term planning of power system. Treating the load duration curve and the system in the stochastic sense takes the place of the inverted load duration curve, effective load duration curve, and the numerical integration in the conventional methods. The time and accuracy of computation are substantially improved due to the fact that all expressions are represented by simple analytic form instead of the existing recursive form.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.4
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• pp.245-251
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• 2018

In this paper, we address some issues in existing seismic hazard closed-form equations and present a novel seismic hazard equation form to overcome these issues. The presented equation form is based on higher-order polynomials, which can well describe the seismic hazard information with relatively high non-linearity. The accuracy of the proposed form is illustrated not only in the seismic hazard data itself but also in estimating the annual probability of failure (APF) of the structural systems. For this purpose, the information on seismic hazard is used in representative areas of the United States (West : Los Angeles, Central : Memphis and Kansas, East : Charleston). Examples regarding the APF estimation are the analyses of existing platform structure and nuclear power plant problems. As a result of the numerical example analyses, it is confirmed that the higher-order-polynomial-based hazard form presented in this paper could predict the APF values of the two example structure systems as well as the given seismic hazard data relatively accurately compared with the existing closed-form hazard equations. Therefore, in the future, it is expected that we can derive a new improved APF function by combining the proposed hazard formula with the existing fragility equation.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.39-44
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• 2009

This paper is concerned with forming technology of an automotive front side member part with ultra high strength steel sheet of DP980. The forming technology considered in this paper is the draw & form type, which installs the upper pad and lower pad to produce the complicated shape of ultra high strength steel sheet. In order to produce sound product, comparison between form type and draw & form type and between draw type and draw & form type are investigated by FE-analysis. FE-analysis is carried out with commercial sheet metal forming analysis S/W, DYNAFORM. It was shown from FE-analysis that the draw & form type satisfied the required specifications such as the dimensional accuracy and soundness of automotive front side member part. The effectiveness of the analytical result was verified by the experiment. From this investigation, the draw & form type is proved to be able to supply useful forming technology in forming ultra high strength steel.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.1
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• pp.40-49
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• 1988

The chip control problem is one of the important subjects to be studied in the metal cutting process. Especially, an important practical problem concerns the form of chips pro- duced in machining since this has important implications relative to : 1. Personal safety. 2. Possible damage to equipment and product. 3. Handling and disposal of swarf after machining. 4. Cutting forces, temperatures, and tool life. However, a dependable way to predict the form of chips in a wide range of cutting conditions has not been established satisfactorily. In this paper, the relationship between the form of chips and the ratios of cutting forces were studied experimentally. According to what the experiments have been carried out in the turning process the main results can be summarized as follows : 1. By use of the multiple linear regression model, emperical formulas which are suitable to wide ranges of cutting conditions with accuracy were obtained satisfactorily. 2. The correlations between the form of chips based upon the classification by Henriksen and the ratios of cutting forces, namely (feeding force/thrust force), (principal force/feeding force) were determined. 3. Using above results, the algorithms which predict the form of chips were constituted. With these algorithms, the form of chips in a wide range of cutting of cutting conditions can be predicted.