• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4042-4049
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• 2024

A new automatic group structure optimization method based on the perturbation theory was proposed for the few-group structure in two-step nuclear design procedure for VHTR. It applies the sensitivity coefficient of the perturbation theory which includes not only the effect of the cross section on the multiplication factor but also the adjoint weighted reaction rate. The sensitivity coefficient of the fine group for the multiplication factor was calculated and the group boundary for a few-group can be determined so that the summation of the fine group sensitivity for a few-group should be evenly distributed over every few-group. This method was successfully implemented in the ABGO code. VHTR-350 and MiHTR 2D core were used to investigate the performance and applicability of the proposed method. The code generated the new group structures for two cores and the error of the multiplication and reaction rate by the new group structure was compared with the result by the fine group structure. The comparisons indicate that the new group structure by the proposed method can provide the multiplication factor and reaction rates comparable to the existing group structure and more accurate results than the group structure obtained using the Contributon theory.

• Journal of Multimedia Information System
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• v.1 no.1
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• pp.45-53
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• 2014

This article describes a two wheelers detection system riding on people based on modified histogram of oriented gradients (HOG) for vision based intelligent vehicles. These features used correlation coefficient parameter are able to classify variable and complicated shapes of a two wheelers according to different viewpoints as well as human appearance. Also our system maintains the simplicity of evaluation of traditional formulation while being more discriminative. In this paper, we propose an evolutionary method trained part-based models to classify multiple view-based detection: frontal, rear and side view (within $60^{\circ}C$). Our experimental results show that a two wheelers riding on people detection system based on proposed approach leads to higher detection accuracy rate than traditional features.

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.515-523
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• 2016

Spectral reflectance is sparse in space, and while the traditional spectral-reconstruction algorithm does not make full use of this characteristic sparseness, the compressive sensing algorithm can make full use of it. In this paper, on the basis of analyzing compressive sensing based on the orthogonal matching pursuit algorithm, a new algorithm based on the Dice matching criterion is proposed. The Dice similarity coefficient is introduced, to calculate the correlation coefficient of the atoms and the residual error, and is used to select the atoms from a library. The accuracy of Spectral reconstruction based on the pseudo-inverse method, Wiener estimation method, OMP algorithm, and DOMP algorithm is compared by simulation on the MATLAB platform and experimental testing. The result is that spectral-reconstruction accuracy based on the DOMP algorithm is higher than for the other three methods. The root-mean-square error and color difference decreases with an increasing number of principal components. The reconstruction error decreases as the number of iterations increases. Spectral reconstruction based on the DOMP algorithm can improve the accuracy of color-information replication effectively, and high-accuracy color-information reproduction can be realized.

• Journal of Environmental Health Sciences
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• v.47 no.1
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• pp.64-77
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• 2021

Objective: Biological monitoring of trace elements in human blood samples has become an important indicator of the health environment. The purpose of this study was to detect and evaluate multiple metal items in blood samples based on ICP-MS, to perform comparative evaluation with the existing analysis method, and to develop and verify a new method. Methods: 100 μL of whole blood from 80 healthy subjects was used to analyze ten metals (Sb, tAs, Cd, Pb, Mn, Hg, Mo, Ni, Se, Tl) using ICP-MS. Verification of the analysis method included calculation of linearity, accuracy, precision and detection limits. In addition, a comparative test with the conventional graphite furnace atomic absorption spectroscopy (GF-AAS) method was performed. In the case of Pb, Cd, and Hg in whole blood, cross-analysis between Pb, Cd, and Hg analysis methods was performed to confirm the difference between the existing method and the new method (ICP-MS). Results: The coefficient of determination (R2) was 0.999 or higher in seven items and 0.995 or higher in three items. The Pb result showed that Pearson's correlation coefficient was very high at 0.983, and the intraclass correlation coefficient was 0.966. The Cd result showed that Pearson's correlation coefficient was 0.917 between the existing method and the new analysis concentration value. Its intraclass correlation coefficient was 0.960, and there was no significant difference between the two groups. Hg had a low correlation at 0.687, and the intraclass correlation coefficient was 0.761, which was lower than that of Pb and Cd. The intra-day and inter-day accuracy of Pd and Cd were satisfactory, but Hg did not meet the criteria for both accuracy and precision when compared with the conventional analysis method. Conclusion: This study can be meaningful in that it proposes a more efficient and feasible analysis method by verifying a blood heavy metal concentration experiment using multiple simultaneous analyses. All samples were processed and analyzed using the new ICP-MS. It was confirmed that the agreement between the two methods was very high, with the agreement between the current and new methods being 0.769 to 0.998. This study proposes an efficient simultaneous methodology capable of analyzing multiple elements with small samples. In the future, studies of various applications and the reliability of ICP-MS analysis methods are required, and research on the verification of accurate, precise, and continuous analysis methods is required.

• Geomechanics and Engineering
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• v.36 no.6
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• pp.631-640
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• 2024

In the traditional slope stability analysis, ignoring the spatial variability of slope soil will lead to inaccurate analysis. In this paper, the K-L series expansion method is adopted to simulate random field of soil strength parameters. Based on Random Limit Equilibrium Method (RLEM), the influence of variation coefficient and fluctuation range on reliability of soil slope supported by micro-pile is investigated. The results show that the fluctuation ranges and the variation coefficients significantly influence the failure probability of soil slope supported by micro-pile. With the increase of fluctuation range of soil strength parameters, the mean safety factor of the slope increases slightly. The failure probability of the soil slope increases with the increase of fluctuation range when the mean safety factor of the slope is greater than 1. The failure probability of the slope increases by nearly 8.5% when the fluctuation range is increased from δ_v=2 m to δ_v =8 m. With the increase of the variation coefficient of soil strength parameters, the mean safety factor of the slope decreases slightly, and the probability of failure of soil slope increases accordingly. The failure probability of the slope increases by nearly 31% when the variation coefficient increases from COV_c=0.2, COV_φ=0.05 to COV_c=0.5, COV_φ=0.2.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.30-34
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• 2012

A safety helmet is a personal protective equipment to protect the head from falling and flying objects. A safety helmet has the maximum delivered impact force as shock absorption performance, the lower delivered impact force the better performance, which was not a controlled variety during manufacturing safety helmet. Accordingly there were some difficulties in establishing the standard for improved performance as there was not a clear controllable impact force for improved performance. In this study the shock absorption performance was intended to be found as coefficient of restitution related to impulse. As a research method, a coefficient of restitution during the absorption of shock was calculated using the impulse transferred to pharynx utilizing the safety helmet shock absorption performance testing device based on the theory of momentum and impulse. The estimated impulsive force curve was derived assuming that shock was not absorbed using the measured data. The sample was selected as tested goods of ABS material for safety certification available mainly in the market. As a result of study, the maximum delivered impact force of safety helmet made by a domestic safety certified a company was 735 N, and its coefficient of restitution proved to be 0.64. The smaller coefficient of restitution is, the lower maximum delivered impact force and the higher shock absorption performance. The coefficient of restitution can be used as a performance index of safety helmet.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.45-53
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• 1985

For the analysis of vertical vibrations of a ship's hull, the Timoshenko beam analogy is accepted up to seven or eight-node modes provided that the system parameters are properly calculated. As to the shear coefficient, it has been a common practice to apply the strain energy method or the projected area method. The theoretical objection to the former is that it ignores lateral contraction due to Poisson's ratio, and the latter is of extreme simplifications. Recently, Cowper's and Stephen's shear coefficient formulas have drawn ship vibration analysts' attentions because these formulas, derivation of which are based on an integrations of the equations of three-dimensional elasticity, take Poisson's ratio into account. Providing computer programs for calculation of the shear coefficient of ship sections modeled as thin-walked multicell sections by each of the forementioned methods, the authors calculated natural vibration characteristics of a bulk carrier and of a container ship by the transfer matrix method using shear coefficients obtained by each of the methods, and discussed the results in comparision. The major conclusions resulted from this investigation are as follows: (1) The shear coefficients taking account of the effects of Poisson's ratio, Cowper's $K_c$ and Stephen's $K_s$, result in higher values of about 10% in maximum as compared with the shear coefficient $K_o$ based on the conventional strain energy methods; (a) $K_c/K_o{\cong}1.05\;and\;K_s/K_o{\cong}1.10$ for ships having single skin side-shell such as a bulk carrier. (b) $K_c/K_o{\cong}1.02\;and\;K_s/K_o{\cong}1.05$ for ships having longitudinally through bulkheads and/or double side-shells in the portion of the cargo hod such as a container carrier. (2) The distributions of the effective shear area along the ship's hull based on each of $K_o,\;K_c\;and\;K_s$ are similar each another except the both end portions. (3) Natural frequencies and mode shapes of the hull based on each of $K_c\;and\;K_s$ are of small differences as compared each other. (4) In cases of using $K_c\;or\;K_s$ in ship vibration analysis, it is also desirable to have the bending rigidity be corrected according to the effective breadth concept. And then, natural frequencies and mode shapes calculated with the bending rigidity corrected in the above and with each of $K_o,\;K_c\;and\;K_s$ result in small differences as compared each another. (5) Referring to those mentioned in the above (3) and (4) and to the full-scale experimental results reported by Asmussen et al.[17], and considering laboursome to prepare the computer input data, the following suggestions can safely be made; (a) Use of $K_o$ in ship vibration analysis is appropriate in practical senses. (b) Use of $K_c$ is appropriate even for detailed vibration analysis of a ship's hull. (6) The effective shear area based on the projected area method is acceptable for the two-node mode.

• Journal of Biomedical Engineering Research
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• v.17 no.3
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• pp.365-372
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• 1996

The researches to acquire diagnostic parameters from ultrasonic images are advanced with the progress of the digital image processing technique. Especially, the detection of endocardial boundary is very important in ultrasonic images, because endocardial boundary is used as a clinical parameter to estimate both the cardiac area and the variation of cardiac volume. Various methods to detect cardiac boundary are proposed, but these are insufficient to detect boundary. In this paper, an algorithm that detects the endocardial boundary, expanding the cavity region from the center using statistical information, is proposed The value of mean and sty:nd, wd deviation in cavity region is lower than those in muscle re- gion. Therefore, if we define the multiplication of mean and standard deviation as homogeneous coefficient, it can lead to conclusion that the pixels with small variation of these coefficleno are cavity region, and extraction of endocardial boundary from cavity region is possible. The proposed method detected endocardial boundary more effectively than edge based or threshold based method and is robuster to noise than radial searching method that has high dependency for center position.

• Current Optics and Photonics
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• v.8 no.3
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• pp.282-299
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• 2024

Target detection (TD) is a research hotspot in the field of hyperspectral imaging (HSI). Traditional TD methods often mine targets from HSIs under a single imaging condition, without considering the influence of imaging conditions. In fact, the spectra of ground objects in HSIs are uncertain and affected by the imaging conditions (weather, atmospheric, light, time, and other angle conditions including zenith angle). Hyperspectral data changes under different imaging conditions. Therefore, the detection result for a single imaging condition cannot accurately reflect the effectiveness of the detection method used. It is necessary to analyze the performance of various detection methods under different imaging conditions, to find a more applicable detection method. In this paper, we study the performance of TD methods under various land-based imaging conditions. We first summarize classical TD methods and evaluation methods. Then, the detection effects under various imaging conditions are analyzed. Finally, the concepts of the stability coefficient (SC) and effective area under the curve (EAUC) are proposed to comprehensively evaluate the applicability of detection methods under land-based imaging conditions, in terms of both detection accuracy and stability. This is conducive to our selection of detection methods with better applicability in land-based contexts, to improve detection accuracy and stability.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.597-611
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• 2013

This paper presents the methodology for construction of time-area curve via the width function and thereby rational estimation of time of concentration and storage coefficient of Clark model within the framework of method of moments. To this end time-area curve is built by rescaling the grid-based width function under the assumption of pure translation and then the analytical expressions for two parameters of Clark model are proposed in terms of method of moments. The methodology in this study based on the analytical expressions mentioned before is compared with both (1) the traditional optimization method of Clark model provided by HEC-1 in which the symmetric time-area curve is used and the difference between observed and simulated hydrographs is minimized (2) and the same optimization method but replacing time-area curve with rescaled width function in respect of peak discharge and time to peak of simulated direct runoff hydrographs and their efficiency coefficient relative to the observed ones. The following points are worth of emphasizing: (1) The optimization method by HEC-1 with rescaled width function among others results in the parameters well reflecting the observed runoff hydrograph with respect to peak discharge coordinates and coefficient of efficiency; (2) For the better application of Clark model it is recommended to use the time-area curve capable of accounting for irregular drainage structure of a river basin such as rescaled width function instead of symmetric time-area curve by HEC-1; (3) Moment-based methodology with rescaled width function developed in this study also gives rise to satisfactory simulation results in terms of peak discharge coordinates and coefficient of efficiency. Especially the mean velocities estimated from this method, characterizing the translation effect of time-area curve, are well consistent with the field surveying results for the points of interest in this study; (4) It is confirmed that the moment-based methodology could be an effective tool for quantitative assessment of translation and storage effects of natural river basin; (5) The runoff hydrographs simulated by the moment-based methodology tend to be more right skewed relative to the observed ones and have lower peaks. It is inferred that this is due to consideration of only one mean velocity in the parameter estimation. Further research is required to combine the hydrodynamic heterogeneity between hillslope and channel network into the construction of time-area curve.