• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.143-152
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• 1999

We have studied a denoising technique involving wavelet transform for improving the quality of geophysical data during the preprocessing stage. To assess the effectiveness of this technique, we have made synthetic data contaminated by random noises and compared the results of denoising with those obtained by conventional low-pass filtering. The low-pass filtering of the sinusoidal signal having a sharp discontinuity between the first and last sample values shows apparent errors related to Gibbs' phenomena. For the case of bump signal, the low-pass filtering induces maximum errors on peak values by removing some high-frequency components of signal itself. The wavelet transform technique, however, denoises these signals with much less adverse effects owing to its pertinent properties on locality of wavelet and easy discrimination of noise and signal in the wavelet domain. The field data of gravity tide are denoised by using soft threshold, which shrinked all the wavelet coefficients toward the origin, and the G-factor is determined by comparing the denoised data and theoretical data.

• Educational Technology International
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• v.25 no.1
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• pp.93-127
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• 2024

This study evaluates the effect of structured debriefing for a business simulation game for university students. The program provides an authentic learning experience of real-world business management by allowing learners to make decisions related to R&D, marketing, production, and finance through a business simulation game, and check the results in real time. In 2022, University A and B each ran a business simulation game-based program as an extra-curricular activity. University A conducted a traditional instructor-led debriefing where the instructor explained the summarized process and results, while University B implemented a structured debriefing which had been developed based on Gibbs' and 3D models. To assess the effect of the structured debriefing compared to the traditional instructor-led debriefing, business knowledge and entrepreneurship competencies were measured three times. Repeated measures ANOVA was used to test for the differences between the two groups and to examine interaction effects between group and time. The structured debriefing group achieved statistically significantly higher academic scores than the traditional instructor-led debriefing group at the post-test and in 2 weeks. There was no statistically significant difference between the groups in terms of entrepreneurship competencies. There was no interaction effect between group and time, both in academic achievement and in entrepreneurship competencies. In conclusion, the simulation game-based program integrated with the structured debriefing session is more likely to have a stronger impact on academic achievement and its retention.

• Korean Management Science Review
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• v.32 no.2
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• pp.69-78
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• 2015

This paper considers a Bayesian Poisson model for multivariate count data using multiplicative rates. More specifically we compose the parameter for overall arrival rates by the product of two parameters, a common effect and an individual effect. The common effect is composed of autoregressive evolution of the parameter, which allows for analysis on seasonal effects on all multivariate time series. In addition, analysis on individual effects allows the researcher to differentiate the time series by whatevercharacterization of their choice. This type of model allows the researcher to specifically analyze two different forms of effects separately and produce a more robust result. We illustrate a simple MCMC generation combined with a Gibbs sampler step in estimating the posterior joint distribution of all parameters in the model. On the whole, the model presented in this study is an intuitive model which may handle complicated problems, and we highlight the properties and possible applications of the model with an example, analyzing real time series data involving customer arrivals to a large retail store.

• Archives of Pharmacal Research
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• v.7 no.2
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• pp.109-113
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• 1984

The critical micelle concentration (CMC) of crude ginseng saponin in water was determined by fluorometry and surface-tension measurement. These two methods gave the the CMC value, 0.015g/100ml AND 0.013G/100ml, respectively. The surface excess of the saponin and the area occupied by a saponin molecule at the monolayer adsorbed at air and waterinterface were calculated employing Gibbs adsorption equation. The presence of salt increased the surface activity of the saponin: it decreased the CMC, the surface tension at the CMC and the area occupied by a saponin molecule at the monolayer, which should be due to the salting-out effect of the salt.

• Communications for Statistical Applications and Methods
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• v.21 no.1
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• pp.45-60
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• 2014

We introduce a MCMC sampling for a generalized linear normal random effects model with the ordered probit link function based on latent variables from suitable truncated normal distribution. Such models have proven useful in practice and we have observed numerically reasonable results in the estimation of fixed effects when the random effect term is provided. Applications that utilize Korean Welfare Panel Study data can be difficult to model; subsequently, we find that an ordered probit model with the random effects leads to an improved analyses with more accurate and precise inferences.

• Communications for Statistical Applications and Methods
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• v.22 no.6
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• pp.625-637
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• 2015

We develop a Bayesian clustering procedure based on a Dirichlet process prior with cluster specific random effects. Gibbs sampling of a normal mixture of linear mixed regressions with a Dirichlet process was implemented to calculate posterior probabilities when the number of clusters was unknown. Our approach (unlike its counterparts) provides simultaneous partitioning and parameter estimation with the computation of the classification probabilities. A Monte Carlo study of curve estimation results showed that the model was useful for function estimation. We find that the proposed Dirichlet process mixture model with cluster specific random effects detects clusters sensitively by combining vague edges into different clusters. Examples are given to show how these models perform on real data.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1183-1186
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• 2007

A shake-flask method was used to determine the n-octanol/water partition coefficients of sulfamethazine, sulfadimethoxine, sulfamethoxydiazine, sulfamonomethoxine, sulfamethoxazole, sulfaquinoxaline and sulfachloropyrazine from (298.15 to 333.15) K. The results showed that the n-octanol/water partition coefficient of each sulfonamide decreased with the increase of temperature. Based on the fluid phase equilibrium theory, the thermodynamic relationship of n-octanol/water partition coefficient depending on the temperature is proposed, and the changes of enthalpy, entropy, and the Gibbs free energy function for sulfonamides partitioning in n-octanol/ water are determined, respectively. Sulfonamides molecules partitioning in n-octanol/water is mainly an enthalpy driving process, during which the order degrees of system increased. The temperature effect coefficient of n-octanol/water partition coefficient is discussed. The results show that its magnitude is the same as that of values in the literature.

• Journal of the Korean Data and Information Science Society
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• v.26 no.3
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• pp.755-762
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• 2015

One of the main objectives of the U.S. Census Bureau is the proper estimation of median household income for small areas. These estimates have an important role in the formulation of various governmental decisions and policies. Since direct survey estimates are available annually for each state or county, it is desirable to exploit the longitudinal trend in income observations in the estimation procedure. In this study, we consider Fay-Herriot type small area models which include time-specific random effect to accommodate any unspecified time varying income pattern. Analysis is carried out in a hierarchical Bayesian framework using Markov chain Monte Carlo methodology. We have evaluated our estimates by comparing those with the corresponding census estimates of 1999 using some commonly used comparison measures. It turns out that among three types of time-specific random effects the small area model with a time series random walk component provides estimates which are superior to both direct estimates and the Census Bureau estimates.

• Journal of the Korean Ceramic Society
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• v.23 no.3
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• pp.35-43
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• 1986

The equilibrium dsorption of starch on activated alumina and kaolin was studied to provide the fundamental data for investigating the effect of polymer adsorption on the flocculation of solid particles. The new polymer adsor-ption model(PAH-FH) predicting the adsorption equilibria of polymers on the solid surface has been developed using the solution theory and the concepts of Gibbs dividing surface in conjunction with the Flory-Huggins eq-uation and the adsorption behaviors of polymers were examined by this model The accurate adsorption equilibrium data of starch on alumina and kaolin were determined within the tempera-ture range of 298-318K by the ignition loss method. Using these experimenta data the model developed in this study was evaluated. It was shown that this model could predict the adsorption isotherm more accura-tely than the Langmuir model as well as could describe the characteristics of the adsorption equilibria through model parameters.

• Communications for Statistical Applications and Methods
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• v.21 no.2
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• pp.193-200
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• 2014

It was recognized by some researchers that the disturbance variance in a censored regression model is frequently underestimated by the maximum likelihood method. This underestimation has implications for the estimation of marginal effects and asymptotic standard errors. For instance, the actual coverage probability of the confidence interval based on a maximum likelihood estimate can be significantly smaller than the nominal confidence level; consequently, a Bayesian estimation is considered to overcome this difficulty. The behaviors of the maximum likelihood and Bayesian estimators of disturbance variance are examined in a fixed effects panel regression model with a limited dependent variable, which is known to have the incidental parameter problem. Behavior under random effect assumption is also investigated.