• Smart Structures and Systems
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• v.29 no.3
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• pp.421-431
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• 2022

Concrete slab cracks monitoring of modern high-speed railway is important for safety and reliability of train operation, to prevent catastrophic failure, and to reduce maintenance costs. This paper proposes a curvature filtering improved crack detection method in concrete slabs of high-speed railway via graph-based anomalies calculation. Firstly, large curvature information contained in the images is extracted for the crack identification based on an improved curvature filtering method. Secondly, a graph-based model is developed for the image sub-blocks anomalies calculation where the baseline of the sub-blocks is acquired by crack-free samples. Once the anomaly is large than the acquired baseline, the sub-block is considered as crack-contained block. The experimental results indicate that the proposed method performs better than convolutional neural network method even under different curvature structures and illumination conditions. This work therefore provides a useful tool for concrete slabs crack detection and is broadly applicable to variety of infrastructure systems.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.38-40
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• 2000

In this paper we propose a calculation method for fuzzy control based on quantized $\alpha$-cut decomposition of fuzzy sets. This method is easy to be implemented in analog hardware. The effect of quantization levels on defuzzified fuzzy inference results is investigated. A few quantization levels are sufficient for fuzzy control. The hardware implementation of this calculation method and the defuzzification by gravity center method by PWM are also presented.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1308-1312
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• 2004

Transmission line impedance calculation has been tried for obtaining exact value. The method proposed by Carson contains indefinite complex integral. Although the Carson solution is proposed with power series, the solution is limited and valid at special range of frequency. In this paper, we proposed a simplified Carson solution by analytical method using ground transmission line return current. This method calculate the transmission line impedance easily.

• Nuclear Engineering and Technology
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• v.45 no.6
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• pp.753-758
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• 2013

A new method of calculating sensitivity coefficients of core characteristics relative to infinite-dilution cross sections has been developed. Conventional sensitivity coefficients are evaluated for the changes of effective cross sections which are dependent on individual models of core and cell. Therefore a correction has been derived to the conventional sensitivity coefficients based on the perturbation theory. The accuracy of the present method has been verified by comparing numerical results of sensitivity coefficients with a reference Monte-Carlo method.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.749-754
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• 1998

This study describes a practical method for the measurement of sustained stress in concrete structures. In most cases, the sustained stress was determined by various theoretical calculation. However, the theoretical calculation can not always provide a sufficient information on the current stress state due to lots of uncertainty. Therefore, the present study proposes a practical in situ measuring method, Partial Sectioning Method

• Journal of Korean Port Research
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• v.15 no.1
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• pp.87-97
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• 2001

The calculation of earthwork plays a major role in plan or design of many civil engineering projects, and thus it has become very important to advanced the accuracy of earthwork calculation. Current method used for estimating the volume of pit excavation assumes that the ground profile between the grid points is linear(trapezoidal rule), or nonlinear(simpson's formulas). In this paper the spot height method, least square method, and chamber formulas, Chen and Lin method are compared with the volumes of the pits in these examples. As a result of this study, algorithm of chen and Lin me쇙 by spline method should provide a better accuracy than the spot height method, least square method, chamber formulas. The Chen and Lin formulas can be used for estimating the excavation volume of a pit divide into a grid with unequal intervals. From the characteristics of the cubic spline polynomial, the modeling curve of the Chen and Lin method is smooth and matches the ground profile well. Generally speaking, the nonlinear profile formulas provide better accuracy than the linear profile formulas. The mathematical model mentioned make an offer maximum accuracy in estimating the volume of a pit excavation.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.81-89
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• 1998

Numerical calculation tools for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear. square spline, internal serrations. A complex calculation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper the workpiece with 110th external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool from combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with others and the calculated solution are useful to predict the capacity of forging equipment.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.621-626
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• 2010

According to development of method and device of Finite Element Analysis, the strength of welded joint is demonstrated by Finite Element Analysis not classical calculations. On the FEA, all of the joints for carbody are assumed to be ideal connections and the yield stress of welded joint is assumed to be the same to base metal. On these assumption, FEA is appropriate to evaluate the overall stability and strength of whole carbody. The classical calculation is appropriate to evaluate strength of specific welded joint and to determine the weld method and properties. Some project request strength calculation of the specific welded joints in addition to FEA, because of the demonstration of stability. The objective of this paper is the check of the consistency of the FEA result for the welded joints by the stress comparison between Detailed FE Model and classical calculation and the evaluation of the reliability of FEA result.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.28-34
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• 2009

In this study firstly we survey the calculation method and the characteristics of the way of estimating CBL(Customer BaseLine Load) that is important calculation tool for DRP internationally. Also we analyze the power consumption pattern using the 15 minutes load profiles of about 120,000 customers in domestic. Based on this pattern, we provide the CBL calculation method that can be utilized in DRP to save the cost, and analyze the accuracy of the CBL calculation proposed in this paper through the simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1269-1274
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• 2012

In this paper, the iron loss was calculated using estimated iron loss coefficient at 650W Interior Permanent Magnet Synchronous Motor(IPMSM) and 250W IPMSM. The iron loss coefficients was estimated different according to electrical steel material used to stator and rotor core in motor. Aspect of The rotating flux field and alternating flux field was confirmed by magnetic field behavior and harmonic analysis in stator core, the iron loss was calculated using flux density by Finite Element Method(FEM) and estimated coefficients by iron loss coefficient estimation proposed in this paper. The iron loss experiment was performed for verified to iron loss calculation, and the iron loss coefficients were verified by comparison of iron loss calculation value and experimental value.