• Smart Structures and Systems
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• v.25 no.2
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• pp.169-181
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• 2020

Sensor placement is a crucial aspect of bridge health monitoring (BHM) dedicated to accurately estimate and locate structural damages. In addressing this goal, a sensor placement framework based on the deflection influence line (DIL) analysis is here proposed, for the optimal design of damage detection-oriented BHM system. In order to improve damage detection accuracy, we explore the change of global stiffness matrix, damage coefficient matrix and DIL vector caused by structural damage, and thus develop a novel sensor placement framework based on the Fisher information matrix. Our approach seeks to determine the contribution of each sensing node to damage detection, and adopts a distance correction coefficient to eliminate the information redundancy among sensors. The proposed damage detection-oriented optimal sensor placement (OSP) method is verified by two examples: (1) a numerically simulated three-span continuous beam, and (2) the Pinghu bridge which has existing real damage conditions. These two examples verify the performance of the distance corrected damage sensitivity of influence line (DSIL) method in significantly higher contribution to damage detection and lower information redundancy, and demonstrate the proposed OSP framework can be potentially employed in BHM practices.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.108-108
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• 1996

This paper describes a new approach to solve balancing of a rigid rotor. In this paper, the balancing of the rigid rotor using genetic algorithms, which are search algorithms based on the mechanics of natural selection and natural genetics is proposed. Under the assumption that the initial vibration values used to calculate correction masses contain errors, the influence coefficient method, the least squares method and a genetic algorithm are compared. The results show that the vibration amplitude obtained with the least squares method and the genetic algorithm is smaller than that obtained with the influence coefficient method.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.40-47
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• 1996

This paper describes a new approach to solve balancing of a rigid rotor. In this paper, the balancing of the rigid rotor using genetic algorithms, which are search algorithms based on the mechanics of natural selection and natural genetics is proposed. Under the assumption that the initial vibration values used to calculate correction masses contain errors, the influence coefficient method, the least squares method and a genetic algorithm are compared. The results show that the vibration amplitude obtained with the least squares method and the genetic algorithm is smaller than that obtained with the influence coefficient method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.6-12
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• 2014

The safety and reliability of the power system short-circuit current, the short-circuit current depends on the failure to obtain the objective is to quickly eliminate the breaking capacity of the circuit-breaker selection of the cable, the insulation of electrical equipment and protective relay an important factor in determining the level correction and protective relay selection scheme to be meaningful. Standards used in the domestic circuit breaker is applied to the production of IEC standard, but the American National Standards (ANSI / IEEE) by NEMA specification of the fault current calculations and the application of the asymmetric coefficient Korea. Therefore, in this paper, the IEC 60909 standard IEC breaker fault current calculation method and the method for selection of system configurations reviewed and protection system for reviewing the configuration of various protective relays appropriate correction and the correction value is main protection, back-up protection the equipment so that the period of protection relay coordination to minimize accidents and accident protection to minimize interruptions proposed for cooperation.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.642-649
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• 2016

Important safety parameters such as the fuel temperature coefficient (FTC) and the power coefficient of reactivity (PCR) of the CANada Deuterium Uranium (CANDU-6) reactor have been evaluated using the Monte Carlo method. For accurate analysis of the parameters, the Doppler broadening rejection correction scheme was implemented in the MCNPX code to account for the thermal motion of the heavy uranium-238 nucleus in the neutron-U scattering reactions. In this work, a standard fuel lattice has been modeled and the fuel is depleted using MCNPX. The FTC value is evaluated for several burnup points including the mid-burnup representing a near-equilibrium core. The Doppler effect has been evaluated using several cross-section libraries such as ENDF/B-VI.8, ENDF/B-VII.0, JEFF-3.1.1, and JENDL-4.0. The PCR value is also evaluated at mid-burnup conditions to characterize the safety features of an equilibrium CANDU-6 reactor. To improve the reliability of the Monte Carlo calculations, we considered a huge number of neutron histories in this work and the standard deviation of the k-infinity values is only 0.5-1 pcm.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.25-30
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• 2011

This study is made to provide with a method for correcting the geometric distortion of the digital radiography image by analytical approach based upon the inverse square law and Beer's law. This study is aimed to find out and improve a mathematic model of nonlinear type. Variations in the alignment of the X-ray source, the object, and imaging plate affect digital radiography images. A model which is expressed in parameter values; e.g, angle, position, absorption coefficient, length, width and pixel account of radiography source, is developed so as to match the sample image. For the best correction of the digital image that is the most similar to the model image, a correction technique based upon tangent is developed; then applied to the digital radiography images of steel tubes. As a result, the image correction is confirmed to be made successfully.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.27-30
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• 2008

Wall correction method for wind tunnel test is reviewed and applied to the numerical experimental results obtained at the wind tunnel condition. The corrected lift coefficient agrees well with the reference data generated from the grid having very far boundary However the corrected drag coefficient presents some deviation from the reference data.

• Korean Journal of Clinical Laboratory Science
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• v.36 no.2
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• pp.137-143
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• 2004

Erythrocyte sedimentation rate(ESR) measurements were performed in a total of 191 blood samples from patients below a hematocrit of 35% by both the Test-1(SIRE Analytical Systems, Udine, Italy) and the Westergren method, endorsed as the reference method for ESR by the International Council for Standardization in Hematology(ICSH). The corrected Westergren ESR values were also obtained applying the formula of Fabry (corrected ESR = ESR measured x 15/55-Hct). Linear regression analysis showed a close correlation (r=0.85) between the two methods both before and after ESR correction in total samples. There was no significant correlation difference between two methods in both two groups with hemoglobin $${\geq_-}9g/dl$$ and <9g/dl before and after ESR correction (r=0.873, r=0.827 respectively before correction and r=0.867, r=0.830 respectively after correction). Also, for two groups with hematocrit $${\geq_-}24%$$ and <24%, no significant difference was observed (r=0.859, r=0.792 respectively before correction and r=0.782, r=0.842 respectively after correction). However, for samples with <60mm of Westergren ESR before correction, a better correlation coefficient was obtained than samples with $${\geq_-}60mm$$(r=0.701, r=0.541 respectively). In corrected Westergren ESR, also samples that were obtained with <40mm showed better correlation than samples with $${\geq_-}40mm$$ (r=0.690, r=0.347 respectively). In conclusion, we found a good correlation between Test-1 and Westergren measurements in patients with anemia but an expert group discussion is required to solve discrepancy between two methods in blood samples with very high ESR.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.116-116
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• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw and total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.48-56
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• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw abd total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.