• Geophysics and Geophysical Exploration
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• v.17 no.1
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• pp.11-20
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• 2014

To reveal shear-wave velocities ($v_s$) and site characterization of Wonju, Korea, Rayleigh waves were recorded at 78 sites of lower altitude using 12 to 24 4.5-Hz vertical geophones for 20 days during the period of February to September 2013. Dispersion curves of the Rayleigh waves obtained by the extended spatial autocorrelation method were inverted using the damped least-squares method to derive $v_s$ models. From these 1-D models, the average $v_s$ to a depth of 30 m ($v_s30$), $v_s$ of weathered rocks, depths to these basement rocks, and average $v_s$ of the overburden layer were derived to be $16.3{\pm}0.7m$, $576{\pm}8m/s$, $290{\pm}7m/s$, and $418{\pm}13m/s$, respectively, in the 95% confidence range. To determine adequate proxies for $v_s30$, we computed correlation coefficients of $v_s30$ with topographic slope (r = 0.46) and elevation (r = 0.43). An empirical linear relationship is presented as a combination of individually estimated $v_s30$ with weighting factors of 0.45, 0.45, and 0.1 for topographic slope, elevation, and mapped lithology, respectively. Due to a weak correlation between $v_s30$ obtained from inversion of dispersion curves and the proxy-based estimation (r = 0.50), however, the relatively large error range should be considered for applications of this relationship.

• Journal of the Korea Computer Graphics Society
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• v.18 no.4
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• pp.1-8
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• 2012

We present improved deformation energy to enhance the visual quality of a shape deformation technique, where we preserve the local structure of an input planar shape. The deformation energy, in general, consists of several constraints such as Laplacian coordinate constraint to preserve the quality of deformed silhouette edges, mean value coordinates and edge length constraints to preserve the quality of deformed internal shape, and user-specified position constraints to control the shape deformation. When the positions of user-specified vertices change, shape deformation techniques compute the positions of the other vertices by means of nonlinear least squares optimization to minimize the deformation energy. When a user-specified vertex changes its position rapidly, it is frequently observed that the visual quality of the deformed shape decrease rapidly, which is mainly caused by unnecessary enlargement of the Laplacian vectors and unnecessary change of the edge directions along the boundary of the shape. In this paper, we propose improved deformation energy by prohibiting the Laplacian and edge length constraints from changing unnecessarily. The proposed deformation energy incorporated with well-known optimization technique can enhance the visual quality of shape deformation along the silhouette and within the interior of the planar shape while sacrificing only a little execution time.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.3
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• pp.457-469
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• 2010

The study aims to estimate interregional trade coefficient of service industry using the gravity model. The gravity model has been widely used for prediction of the level of human interaction between two regions which is positively related to attraction of them and negatively related to the distance between them. To apply the gravity model for explaining the interregional trade flow of service industry, the choice of proper proxy variables which represent a dependent variable and independent variables is most important. However, the literature shows that there are few studies on this issue. Four models concerned to the choice of proxy variables are considered. Finally, this paper employs the least-squares regression analysis to test the model's goodness-of-fit, and suggests the most appropriate model based on the result from the analysis. The result shows that the interregional trade of service industry in regional input-output table developed by The Bank of Korea is desirable as a dependent variable, the service industry output of export region, the population of import region, and the spatial distance between regions are desirable as independent variables.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.649-656
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• 2011

A model for the numerical simulation of lithium-ion batteries (LIBs) is developed for use in battery cell design, with a view to improving the performances of such batteries. The model uses Newman-type electrochemical and transfer $theories^{(1,2)}$ to describe the behavior of the lithium-ion cell, together with the Levenberg-Marquardt optimization scheme to estimate the performance or design parameters in nonlinear problems. The mathematical model can provide an insight into the mechanism of LIB behavior during the charging/discharging process, and can therefore help to predict cell performance. Furthermore, by means of least-squares fitting to experimental discharge curves measured at room temperature, we were able to obtain the values of transport and kinetic parameters that are usually difficult to measure. By comparing the calculated data with the life-test discharge curves (SB LiMotive cell), we found that the capacity fade is strongly dependent on the decrease in the reaction area of active materials in the anode and cathode, as well as on the electrolyte diffusivity.

• Investigative Magnetic Resonance Imaging
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• v.20 no.1
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• pp.44-52
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• 2016

Purpose: To quantitatively and qualitatively compare fat-suppressed MRI quality using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with that using frequency selective fat-suppression (FSFS) T2- and postcontrast T1-weighted fast spin-echo images of the head and neck at 3T. Materials and Methods: The study was approved by our Institutional Review Board. Prospective MR image analysis was performed in 36 individuals at a single-center. Axial fat suppressed T2- and postcontrast T1-weighted images with IDEAL and FSFS were compared. Visual assessment was performed by two independent readers with respect to; 1) metallic artifacts around oral cavity, 2) susceptibility artifacts around upper airway, paranasal sinus, and head-neck junction, 3) homogeneity of fat suppression, 4) image sharpness, 5) tissue contrast of pathologies and lymph nodes. The signal-to-noise ratios (SNR) for each image sequence were assessed. Results: Both IDEAL fat suppressed T2- and T1-weighted images significantly reduced artifacts around airway, paranasal sinus, and head-neck junction, and significantly improved homogeneous fat suppression in compared to those using FSFS (P < 0.05 for all). IDEAL significantly decreased artifacts around oral cavity on T2-weighted images (P < 0.05, respectively) and improved sharpness, lesion-to-tissue, and lymph node-to-tissue contrast on T1-weighted images (P < 0.05 for all). The mean SNRs were significantly improved on both T1- and T2-weighted IDEAL images (P < 0.05 for all). Conclusion: IDEAL technique improves image quality in the head and neck by reducing artifacts with homogeneous fat suppression, while maintaining a high SNR.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.642-653
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• 2008

This study deals with modeling of head-related transfer functions(HRTFs) using principal components analysis(PCA) in the time and frequency domains. Four PCA models based on head-related impulse responses(HRIRs), complex-valued HRTFs, augmented HRTFs, and log-magnitudes of HRTFs are investigated. The objective of this study is to compare modeling performances of the PCA models in the least-squares sense and to show the theoretical relationship between the PCA models. In terms of the number of principal components needed for modeling, the PCA model based on HRIR or augmented HRTFs showed more efficient modeling performance than the PCA model based on complex-valued HRTFs. The PCA model based on HRIRs in the time domain and that based on augmented HRTFs in the frequency domain are shown to be theoretically equivalent. Modeling performance of the PCA model based on log-magnitudes of HRTFs cannot be compared with that of other PCA models because the PCA model deals with log-scaled magnitude components only, whereas the other PCA models consider both magnitude and phase components in linear scale.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.628-634
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• 2006

This study was performed to investigate the quality of pre-processed vegetables used in school and institutional food-services. Pre-processed food materials (carrot, potato, and cabbage) frequently used in food-service were collected from 14 various processing company sources. The sensory and physico-chemical qualities of the pre-processed food materials were determined using sensory and instrumental analysis. For the physico-chemical analysis of the food materials, pH, total acidity, hardness, Hunter colorimeter value, reducing sugar and vitamin C content were determined. For the sensory quality evaluation, 15 panelist were trained and consensus was reached on the quality standards of the preprocessed materials (carrot, potato, and cabbage). Finally, appearance, color, texture, off-odor/taste, and overall quality were determined. In the physico-chemical analysis, there were no significant differences among samples collected from various processing companies. In sensory quality evaluations, the color quality of pre-processed potato was lower than that of other materials. From the coefficient correlations and partial least squares regression analysis between sensory and instrumental data, pH, total acidity, colorimeter values, and hardness were considered important components in assessing the quality of pre-processed vegetables.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.77-90
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• 2009

Near Infrared Reflectance Spectroscopy(NIRS) is a quick, accurate, and non-destructive method to measure multiple nutrient components in plant leaves. This study was to acquire a liner regression equation by evaluating the nutrient contents of 'CY2' creeping bentgrass rapidly and accurately using NIRS. In particular, nitrogen fertility is a primary element to keep maintaining good quality of turfgrass. Nitrogen, moisture, carbohydrate, and starch were assessed and analyzed from 'CY2' creeping bentgrass clippings. A linear regression equation was obtained from accessing NIRS values from NIR spectrophotometer(NIR system, Model XDS, XM-1100 series, FOSS, Sweden) programmed with WinISI III project manager v1.50e and ISIscan(R) (Infrasoft International) and calibrated with laboratory values via chemical analysis from an authorized institute. The equation was formulated as MPLS(modified partial least squares) analyzing laboratory values and mathematically pre-treated spectra. The accuracy of the acquired equation was confirmed with SEP(standard error of prediction), which indicated as correlation coefficient($r^2$) and prediction error of sample unacquainted, followed by the verification of model equation of real values and these monitoring results. As results of monitoring, $r^2$ of nitrogen, moisture, and carbohydrate in 'CY2' creeping bentgrass was 0.840, 0.904, and 0.944, respectively. SEP was 0.066, 1.868, and 0.601, respectively. After outlier treatment, $r^2$ was 0.892, 0.925, and 0.971, while SEP was 0.052, 1.577, and 0.394, respectively, which totally showed a high correlation. However, $r^2$ of starch was 0.464, which appeared a low correlation. Thereof, the verified equation appearing higher $r^2$ of nitrogen, moisture, and carbohydrate showed its higher accuracy of prediction model, which finally could be put into practical use for turf management system.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.320-329
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• 1977

p-Phenylenediamine dihydroperchlorate, $C_6H_4N_2H_4{\cdot}2HC1O_4$, crystallizes in space group $P\={1}$ with $a=4.79{\pm}0.02,\;b=9.03{\pm}0.02,\;c=7.12{\pm}0.03{\AA},\;{\alpha}=109.4{\pm}0.2,\;{\beta}=79.6{\pm}0.2,\;r=104.6{\pm}0.2^{\circ},\;Z=1$. The structure has been solved by the Patterson and Fourier methods. The refinement by block-diagonal least-squares cycles gives R = 0.13 for 387 observed reflexions collected on equi-inclination Weissenberg photographs with CuK${\alpha}$ radiation. There are two different types of five hydrogen bonds. The first type consists of one trifurcated N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.ce anaysis of our samples and investigated the variarions in the values of parameters obtained through fitting the theoretical impedance to the experimental impedance. The characters of the dielectric constant and the impedance showed abnormal variations for the 0.2 at K-doped NSBN ceramics, which we were able to interpret in terms of the variations in the number A-site vacancies with the K doping ratio. From these results, A-site vacancies are thought to be space charges that influence the ferroelectric properties of NSBN ceramics.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.307-319
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• 1977

The crystal structure of $N-({\alpha}-dimethyl\;{\beta}-hydroxy)ethyl\;N'-cyclohexyl\;thiourea,\;C_{ll}H_{22}N_2OS)$, has been determined by X-ray diffraction method. The compound crystallizes in the orthorhombic space group Pbca with a = 10.33(3), b = 11.82(3), c = 22.57(4)${\AA}$ and Z = 8. A total of 1414 observed reflections collected by the Weissenberg photographs and was solved by heavy atom method and refined by block diagonal least-squares methods to the R value of 0.13. The cyclohexane ring has a normal chair conformation and the thiourea unit is planar. The primary alcoholic group O-H bonded to C(l) makes an intramolecular hydrogen bond with N(2), which leads to stablize the molecule. There are two independent hydrogen bonds in the structure. One of them is of the type N-H${\cdot}{\cdot}{\cdot}$O intramolecular hydrogen bond with the length 2.71${\AA}$, another is of the type O-H${\cdot}{\cdot}{\cdot}$S intermolecular hydrogen bond with the length 3.21${\AA}$ parallel to the b axis. Apart from the hydrogen bonding system the molecules are held together by van der Waals forces in the crystal.