• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.62.2-62.2
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• 2016

We present a newly developed algorithm based on a Bayesian method for 2D tilted-ring analysis of disk galaxies which operates on velocity fields. Compared to the conventional ones based on a chi-squared minimisation procedure, this new Bayesian-based algorithm less suffers from local minima of the model parameters even with high multi-modality of their posterior distributions. Moreover, the Bayesian analysis implemented via Markov Chain Monte Carlo (MCMC) sampling only requires broad ranges of posterior distributions of the parameters, which makes the fitting procedure fully automated. This feature is essential for performing kinematic analysis of an unprecedented number of resolved galaxies from the upcoming Square Kilometre Array (SKA) pathfinders' galaxy surveys. A standalone code, the so-called '2D Bayesian Automated Tilted-ring fitter' (2DBAT) that implements the Bayesian fits of 2D tilted-ring models is developed for deriving rotation curves of galaxies that are at least marginally resolved (> 3 beams across the semi-major axis) and moderately inclined (20 < i < 70 degree). The main layout of 2DBAT and its performance test are discussed using sample galaxies from Australia Telescope Compact Array (ATCA) observations as well as artificial data cubes built based on representative rotation curves of intermediate-mass and massive spiral galaxies.

• The Korean Journal of Applied Statistics
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• v.26 no.3
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• pp.441-452
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• 2013

This study analyzed the relationship between key film and a box office record success factors based on movies released in the first quarter of 2013 in Korea. An over-fitting problem can happen if there are too many explanatory variables inserted to regression model; in addition, there is a risk that the estimator is instable when there is multi-collinearity among the explanatory variables. For this reason, optimal variable selection based on high explanatory variables in box-office performance is of importance. Among the numerous ways to select variables, LASSO estimation applied by a generalized linear model has the smallest prediction error that can efficiently and quickly find variables with the highest explanatory power to box-office performance in order.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.7
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• pp.1184-1196
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• 2010

Several applications of body scanning technology have been commercialized or are currently under development. The virtual fit from 3D scans is most advanced form of virtual try-on. This article is an analysis of the comparison of user preferences for domestic versus foreign 3D virtual try-on systems. For this study, domestic i-Fashion Mall (www.ifashionmall.co.kr) and a Canadian company, My Virtual Model (www.mvm.com) were selected as the most representative online retailers that offer a virtual try-on system. The respondents were comprised of 70 Korean female college students in the age group 20-29. A five point Likert scale was used to evaluate the degree of the preference of virtual avatar and try-on images. T-test, cross table, and a chi-square independence test were conducted for data analysis. The results are as follow. 1. The representation about current looks according to each virtual fit image indicates that MVM is more accurate than i-Fashion Mall. 2. About decision confidence, respondents have decision confidence in i-Fashion Mall in the case of the avatar image; however, respondents have confidence in MVM or the fit image. 3. There were no significant differences in among waist size groups in accuracy, trust of each avatar image, while there were significant differences among waist size groups in the accuracy and trust of each virtual fit image. 4. About ease of use, respondents answered that i-Fashion Mall is superior to MVM. 5. The respondents prioritized the ‘fitting report’ of i-Fashion Mall and ‘Weight loss’ of MVM over other functionalities.

• Computers and Concrete
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• v.31 no.4
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• pp.349-358
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• 2023

This paper describes an in-depth analysis on flexural strength of a girder-deck system experiencing a strand debonding damage with various strengthening systems, based on finite element software ABAQUS. A detailed finite element analysis (FEA) model was developed and verified against the relevant experimental data performed by other researchers. The proposed analytical model showed a good agreement with experimental data. Based on the verified FE model, over a hundred girder-deck systems were investigated with the consideration of following variables: 1) debonding level, 2) span-to-depth ratio (L/d), 3) strengthening type, 4) strengthening material thickness. Based on the data above, a new detailed analytical model was developed and proposed for estimating residual flexural strength of the strand-debonding damaged girder-deck system with strengthening systems. It was demonstrated that both finite element model and analysis model could be used to predict flexural behaviors for debonding damaged prestressed girder-deck systems. Since the strands are debonding from surrounding concrete over a certain zone over the length of the beam, the increase of strain in strands can be linked with a ratio ψ, which is L_p/c. The analytical model was proposed and developed regarding the ratio ψ. By conducting procedure of calculating ψ, the ψ value varies from 9.3 to 70.1. Multiple nonlinear regression analysis was performed in Software IBM SPSS Statistics 27.0.1 to derive equation of ψ. ψ equation was curved to be an exponential function, and the independent variable (X) is a linear function in terms of three variables of debonding level (λ), span length (L), and amount of strengthening material (A_s). The coefficient of determinate (R²) for curve fitting in nonlinear regression analysis is 0.8768. The developed analytical model was compared to the ultimate capacities computed by FEA model.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.31-38
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• 2014

The purpose of this study is to make virtual machine using a 3D modeller to perform reverse engineering. Through the intuitive designer's ability, approximated model of the object is created and used to extract the data and NC tool path. The extracted data make approximated curve by using NURBS curve fitting. And the curve is used to remodel. From these series of process, the final reverse engineering data of the objects can be obtained. Two conclusions are drawn from this study. First, initial deviation of the intuitive model is one of the important factors that determine the number of repetitions of the experiment. Due to the characteristic of intuitive curve, after a certain number of repetitions the average deviation increase and radiate rather than decrease.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.3-6
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• 2001

Various Parameters such as stream velocities, discharges, and dispersion coefficients of dissolved solutes were estimated by fitting 1-D nonreactive solute transport model to the time-series chemistry data. This study was done for the reaches of Mankyung River lower than the Jeonju Wastewater Treatment Plant (Jeonju WTP). Korea. Concentrations of inorganic chemicals in the stream waters are strongly influenced by mixing with the chemically distinct effluent from Jeonju WTP. Sulfate, EC. and the total major cation were proved to be nearly conservative in the study area front their relationships with chloride, the conservative chemical species. The solute transport model was constrained to the time-series concentrations for these 4 conservative species. The variations of concentration and discharge of Jeonju WTP were used as input parameters, and the stream velocities, dispersion coefficients, and concentrations and discharges of some inflows were optimized. The differences between the observed arid simulated values for alkalinities and nitrates are inversely correlated and show diurnal fluctuations, indicating the photosynthesis. The parameters obtained front this mode] range from 550 to 774 kcmd (stream discharge at the outlet of the study area), from 0.06 to 0.10 m/sec (flow velocity), and from 0.7 to 6.4 m$^2$/sec (dispersion coefficient). The history of Jeonju WTP discharge was well predicted when optimized, indicating the validity of the model results.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1813-1824
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• 2022

This paper shows the verification work of SARAX code system in the reactor core transient calculation based on the simplified EBR-II Benchmark. The SARAX code system is an analysis package developed by Xi'an Jiaotong University and aims at the advanced reactor R&D. In this work, a neutron-photon coupled power calculation model and a spatial-dependent reactivity feedback model were introduced. To verify the models used in SARAX, the EBR-II SHRT-45R test was simplified to an ULOF transient with an input flowrate change curve by fitting from reference. With the neutron-photon coupled power calculation model, SARAX gave close results in both power fraction and peak power prediction to the reference results. The location of the hottest assembly from SARAX and reference are the same and the relative power deviation of the hottest assembly is 2.6%. As for transient analysis, compared with experimental results and other calculated results, SARAX presents coincident results both in trend and absolute value. The minimum value of core net reactivity during the transient agreed well with the reported results, which ranged from -0.3$ to -0.35$. The results verify the models in SARAX, which are correct and able to simulate the in-core transient with reliable accuracy.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.31-36
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• 2006

By analyzing the Ge 34 core-level photoelectron spectrum, we studied the structure of the $Li/Ge(111)-3\times1$ surface. Two surface related components tying on either side of the main bulk peak were identified in the Ge 3d spectrum. The existence and the position of the two surface components in the core-level spectrum from $Li/Ge(111)-3\times1$ is similar to those of the $Li/Ge(111)-3\times1$, suggesting the similarities in structure of the two surfaces. The core-level photoelectron spectra of the Li-induced $Li/Ge(111)-3\times1$ surface are well consistent with the honeycomb-chain-channel model, which was proposed as the structure of the $Si/Ge(111)-3\times1$ induced by alkali metals.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.141.2-141.2
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• 2011

We present physical parameters of the detached eclipsing binary KIC3858884, which has a d-Scuti type pulsating secondary component. To derive orbital elements from radial-velocity curve, high-resolution Echelle spectra were obtained at the Bohyunsan Optical Astronomy Observatory in Korea. The BOES spectra and Kepler photometric data were analyzed with JKTEBOP and Wilson-Devinney model for eclipsing light-curve synthesis and Period04 for pulsation frequency analysis. After the iterative curve fitting, we determined physical parameters of KIC3858884 as $M_1=2.02{\pm}0.23M_{\odot}$, $M_2=2.02{\pm}0.16M_{\odot}$, $R_1=3.61{\pm}0.12R_{\odot}$, $R_2=2.84{\pm}0.10R_{\odot}$, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.709-721
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• 2008

This paper is to test the applicability of ModKIMSTORM (Modified KIneMatic Wave STOrm Runoff Model) by applying it to Namgangdam watershed of $2,293km^2$. Model inputs (DEM, land use, soil related information) were prepared in 500 m spatial resolution. Using five typhoon events (Saomi in 2000, Rusa in 2002, Maemi in 2003, Megi in 2004 and Ewiniar in 2006) and two storm events (May of 2003 and July of 2004), the model was calibrated and verified by comparing the simulated streamflow with the observed one at the outlet of the watershed. The Pearson's coefficient of determination $R^2$, Nash and Sutcliffe model efficiency E, the deviation of runoff volumes $D_v$, relative error of the peak runoff rate $EQ_p$, and absolute error of the time to peak runoff $ET_p$ showed the average value of 0.984, 0.981, 3.63%, 0.003, and 0.48 hr for 4 storms calibration and 0.937, 0.895, 8.08%, 0.138, and 0.73 hr for 3 storms verification respectively. Among the model parameters, the stream Manning's roughness coefficient was the most sensitive for peak runoff and the initial soil moisture content was highly sensitive for runoff volume fitting. We could look into the behavior of hyrologic components from the spatial results during the storm periods and get some clue for the watershed management by storms.