• The Journal of the Korea Contents Association
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• 제16권10호
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• pp.382-392
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• 2016

This study organize a self-directed learning in complex structures. And based on this, It was developed self-directed learning scale for university students. It was a analyzing literature and reviewing previous studies for developed scale. Therefore, Self-directed learning model was configured into motives, performance behaviors, and learning management behaviors. On the basis of this, the present study constructed 19 sub-factors and developed 114 scale items. First, a preliminary scale was developed and its reliability was assessed by administering the scale to 128 students attending A university. The result showed that the reliability of every sub-factor was good and, therefore, the scale was developed with no item removed. To verify the validity of the scale, this study evaluated reliability and construct validity by administering the scale to 674 students going to A university. The reliability and validity of all sub-factors were found to be good. A confirmatory factor analysis was performed to verify construct validity and the result revealed that the first model was not an appropriate model. For this reason, the first model was modified once by taking the model modification index into account and it was found that ${\chi}^2$ (563.254), CFI=.963, NFI=.951, RMSEA=.064. Thus, the model was verified as a valid model. The results of this study imply that it is possible to point out learners' weaknesses and strengths by measuring activities taking place in the learning process in detail.

• Asia Marketing Journal
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• 제11권1호
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• pp.29-38
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• 2009

Estimating the Bass diffusion model often creates a time-interval bias, which leads the OLS approach to overestimate sales at early stages and underestimate sales after the peak. Further, a specification error from omitted variables might raise serial correlations among residuals when marketing actions are not incorporated into the diffusion model. Autocorrelated disturbances may yield unbiased but inefficient estimation, and therefore invalid inference results. This phenomenon warrants a modified approach to estimating the Bass diffusion model. In this paper, the authors propose a modified Bass diffusion model handling autocorrelated disturbances. To validate the new approach, authors applied the method on two different data-sets: CT Scanners in the U.S, and FPD TV sales in Korea. The results showed improved model fit and the validity of the proposed model.

• The Korean Journal of Applied Statistics
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• 제18권2호
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• pp.435-443
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• 2005

Coefficients of determination in logistic regression analysis are defined as various statistics, and their values are relatively smaller than those for linear regression model. These coefficients of determination are not generally used to evaluate and diagnose logistic regression model. Liao and McGee (2003) proposed two adjusted coefficients of determination which are robust at the addition of inappropriate predictors and the variation of sample size. In this work, these adjusted coefficients of determination are applied to variable selection method for logistic regression model and compared with results of other methods such as the forward selection, backward elimination, stepwise selection, and AIC statistic.

• The Korean Journal of Applied Statistics
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• 제34권2호
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• pp.205-223
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• 2021

In this paper, we study a method to determine the existence of unit roots by using the adaptive lasso. The previously proposed method that applied the adaptive lasso to the original time series has low power when there is an unknown trend. Therefore, we propose a modified version that fits the ADF regression model without deterministic component using the adaptive lasso to the detrended series instead of the original series. Our Monte Carlo simulation experiments show that the modified method improves the power over the original method and works well in large samples.

• Journal of the Korean Data and Information Science Society
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• 제22권3호
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• pp.401-412
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• 2011

This study uses a vector error correction model to analyze the daily time series data of the spot price of EUA (European Union Allowance). As endogenous variables, five variables are considered for the analysis, including prices of crude oil, natural gas, electricity and coal in addition to carbon price. Data period is Phase 2 period (April 21, 2008 to March 31, 2010) to avoid Phase 1 period (2005-2007) where the EUA prices were distorted. Unit-root and cointegration test results reveal that all variables have a unit root and cointegration vectors exist, so a vector error correction model is adopted instead of a vector autoregressive model.

• Korean Journal of Optics and Photonics
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• 제18권2호
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• pp.167-170
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• 2007

In this study, clinical data for emmetopia in young Koreans was taken in order to design the finite schematic eye, which had optical properties of real eyes including spherical aberration, astigmatism, field curvature and distortion. Furthermore, the crystalline lens with GRIN medium was optically analyzed, and the finite schematic eye with the GRIN crystalline lens was designed.

• Management & Information Systems Review
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• 제39권2호
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• pp.145-162
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• 2020

This study examines problems with using the conventional analytic hierarchy process (AHP) method and proposes a method of weight adjustment as a modification of AHP. AHP is a method for transforming complex decision problems into a hierarchal structure, which is composed of elements in the upper and lower levels and then using pairwise comparisons to evaluate these elements and subsequently to obtain their relative weights. The elements' relative importance is reliable if the elements in the lower hierarchical levels (sub factors) that comprise each element in the upper hierarchical level (primary factor) are equal in number. In other words, if the number of sub factors is different for each primary factor, a serious error is expected as a result. Therefore, this study proposes a modification of AHP that can avoid such an error when AHP is used. Specifically, an error that arises from different number of sub factors (matrix size) can be overcome by making the number of sub factors identical for each primary factor. The resulting model has been validated through the applications in different AHP hierarchical structures.

• Korean Journal of Social Welfare
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• 제64권4호
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• pp.209-231
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• 2012

Recently, the many anti- stigma program use the 'mental illness is an illness like any other biogenetic illness' approach. This is based on Weiner's attribution affection theory. However, mental illness is difficult to be applied with attribution affection premise because attributing no blame for mental problem(biogenetic cause) leads to fear and dangerousness. We proposed a modified attribution affection model that explains the relations between biogenetic causal belief and social distance. Our model assumed that attributing personal responsibility for each mental problem leads to anger and social distance. And attributing no blame for mental problem(biogenetic causal belief) reinforces perception of dangerousness and social distance. This study presented typical vignettes of schizophrenia, depression and alcoholism according to the diagnosis criteria of DSM-IV to 768 university students randomly. Path analysis was used to test modified attribution affection model. The major findings are, First our original model modified partially for fit index. So final model assumed that i) The more respondents believed personal responsibility, the more anger, the more anger reaction corresponded closely with more social distance. ii) biogenetic causal beliefs leads to a worsening of dangerousness and perception of dangerousness leads to a increasing of social distance. Second, multi-group analysis was conducted to verify how a modified attribution affection model would be applicable to three groups. The result is that there is no difference among three groups. Finding from this research suggest to change anti-stigma program that use medical model.

• Journal of Korean Society of Transportation
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• 제26권4호
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• pp.63-76
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• 2008

The goals of this study are to develop travel time functions based on intersection delay and to analyze the applicability of the functions to traffic assignment models. The study begins with the premise that the existing assignment models can not effectively account for intersection delay time. In pursuing the goals, this study gives particular attention to dividing the link travel time into link moving time and stopped time at node, making the models based on such variables as the travel speed, volume, geometry, and signal data of signalized intersections in Cheongju, and analyzing the applicability of these models to traffic assignment. There are several major findings. First, the study presents the revised percentage of lanes (considering type of intersection) instead of g/C for calculating intersection delay, which is analyzed to be significant in the paired t-test. Second, the assigned results of applying these models to the Cheongju network in EMME/2 are compared with the data observed from a test car survey in Cheongju. The analyses show that the BPR models do not consider the intersection delay, but the modified uniform delay model and modified Webster model are comparatively well fitted to the observed data. Finally, the assigned results of applying these models are statistically compared with the test car survey data in assigned volume, travel time, and average speed. The results show that the estimates from the divided travel time model are better fitted to observed data than those from the BPR model.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2002년도 학술발표회 논문집(II)
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• pp.1223-1229
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• 2002