• Imaging Science in Dentistry
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• v.32 no.1
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• pp.27-33
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• 2002

Purpose: To evaluate the influence of threshold value of computed tomography on the accuracy of rapid prototyping (RP) medical model Material and Methods : CT datas of a human dry skull were transferred from CT scanner via compact disk to a personal computer (PC). 3-dimensional image reconstruction on PC by V-works/sup TM/ 3.0 (CyberMed. Inc.) software and RP models fabrication were followed. 2-RP models were produced by threshold value of 500 and 800 selected in surface rendering process. Linear measurements between arbitrary 12 anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared. Thus, the accuracy of 500 RP and 800RP models was respectively evaluated. Results: There was mean difference (% difference) in absolute value of 2.27 mm (2.73%) between linear measurements of dry skull and 500 RP model. There was mean difference (% difference) in absolute value of 1.94 mm (2.52%) between linear measurements of dry skull and 800 RP model. Conclusion: Slight difference of threshold value in rendering process of 3-D modelling made a influence on the accuracy of RP medical model.

• Design Convergence Study
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• v.16 no.3
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• pp.17-37
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• 2017

The purpose of this study is to evaluate the value of the center of age-friendly goods to confirm the public value of the center. 152 elderly participants, either who have utilized the center themselves or who have experienced the center indirectly through the image have participated in the study. The experience of age-friendly product center was evaluated by the contingent valuation method, which is widely used in the public services. A double-bounded dichotomous choice (DB-DC) log-logistic model and a log-normal model were conducted. As the result of the estimation, the truncated mean of the log-logistic model was 3,401 Korean won, with the mean of 4,937 won. In addition, the truncated mean of the log-normal model was 3,433 won, with the mean of 4,144 won. Elderly who have not experienced the center placed a higher value on the center, compared to the experienced elderly. The results imply the necessity to enlarge the opportunity for future suppliers to experience the center for age-friendly products, in order to improve their objective understandings. In addition, the necessity of expanding exhibition products and applying age-friendly designs is proposed, to offer various attractive experiences to elderly.

• East Asian mathematical journal
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• v.5 no.1
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• pp.95-110
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• 1989

In a general variance component model, nonnegative quadratic estimators of the components of variance are considered which are invariant with respect to mean value translaion and have minimum bias (analogously to estimation theory of mean value parameters). Here the minimum is taken over an appropriate cone of positive semidefinite matrices, after having made a reduction by invariance. Among these estimators, which always exist the one of minimum norm is characterized. This characterization is achieved by systems of necessary and sufficient condition, and by a cone restricted pseudoinverse. In models where the decomposing covariance matrices span a commutative quadratic subspace, a representation of the considered estimator is derived that requires merely to solve an ordinary convex quadratic optimization problem. As an example, we present the two way nested classification random model. An unbiased estimator is derived for the mean squared error of any unbiased or biased estimator that is expressible as a linear combination of independent sums of squares. Further, it is shown that, for the classical balanced variance component models, this estimator is the best invariant unbiased estimator, for the variance of the ANOVA estimator and for the mean squared error of the nonnegative minimum biased estimator. As an example, the balanced two way nested classification model with ramdom effects if considered.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.499-507
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• 2018

Agricultural meteorological information is an important resource that affects farmers' income, food security, and agricultural conditions. Thus, such data are used in various fields that are responsible for planning, enforcing, and evaluating agricultural policies. The meteorological information obtained from automatic weather observation systems operated by rural development agencies contains missing values owing to temporary mechanical or communication deficiencies. It is known that missing values lead to reduction in the reliability and validity of the model. In this study, the hierarchical Bayesian spatio-temporal model suggests replacements for missing values because the meteorological information includes spatio-temporal correlation. The prior distribution is very important in the Bayesian approach. However, we found a problem where the spatial decay parameter was not converged through the trace plot. A suitable spatial decay parameter, estimated on the bias of root-mean-square error (RMSE), which was determined to be the difference between the predicted and observed values. The latitude, longitude, and altitude were considered as covariates. The estimated spatial decay parameters were 0.041 and 0.039, for the spatio-temporal model with latitude and longitude and for latitude, longitude, and altitude, respectively. The posterior distributions were stable after the spatial decay parameter was fixed. root mean square error (RMSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and bias were calculated for model validation. Finally, the missing values were generated using the independent Gaussian process model.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.15
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• pp.6115-6120
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• 2014

Background: To compare the KKU-model rectal tube (KKU-tube) and the conventional rectal tube (CRT) for checking rectal doses during high-dose-rate intracavitary brachytherapy (HDR-ICBT) of cervical cancer. Materials and Methods: Between February 2010 and January 2011, thirty -two patients with cervical cancer were enrolled and treated with external beam radiotherapy (EBRT) and intracavitary brachytherapy (ICBT). The KKU-tube and CRT were applied intrarectally in the same patients at alternate sessions as references for calculation of rectal doses during ICBT. The gold standard references of rectum anatomical markers which are most proximal to radiation sources were anterior rectal walls (ARW) adjacent to the uterine cervix demonstrated by barium sulfate suspension enema. The calculated rectal doses derived from actual anterior rectal walls, CRT and the anterior surfaces of the KKU-tubes were compared by using the paired t-test. The pain caused by insertion of each type of rectal tube was assessed by the visual analogue scale (VAS). Results: The mean dose of CRT was lower than the mean dose of ARW ($Dmean_0-Dmean_1$) by $80.55{\pm}47.33cGy$ (p-value <0.05). The mean dose of the KKU-tube was lower than the mean dose of ARW ($Dmean_0-Dmean_2$) by $30.82{\pm}24.20cGy$ (p-value <0.05). The mean dose difference [($Dmean_0-Dmean_1$)-($Dmean_0-Dmean_2$)] was $49.72{\pm}51.60cGy$, which was statistically significant between 42.32 cGy -57.13 cGy with the t-value of 13.24 (p-value <0.05). The maximum rectal dose by using CRT was higher than the KKU-tube as much as 75.26 cGy and statistically significant with the t-score of 7.55 (p-value <0.05). The mean doses at the anterior rectal wall while using the CRTs and the KKU-tubes were not significantly different (p-value=0.09). The mean pain score during insertion of the CRT was significantly higher than the KKU-tube by a t-score of 6.15 (p-value <0.05) Conclusions: The KKU-model rectal tube was found to be an easily producible, applicable and reliable instrument as a reference for evaluating the rectal dose during ICBT of cervical cancer without negative effects on the patients.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.415-424
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• 2013

Purpose: This study is to present a standard value for clinical crown angulation and inclination required in laboratory process and see if the value can be used for actual laboratory process. Methods: In order to find out a standard value for clinical crown angulation and inclination, this study made a study model of normal occlusion of 21 females in twenties. The clinical crown angulation and inclination of both six-maxillary and six-mandibular anterior teeth are measured by Set-up Model Checker. From the measured value above, the mean and standard deviation of the twelve teeth are obtained, and then the mean of the teeth between right and left side is calculated. Results: Each clinical crown angulation of maxillary central incisor, lateral incisor, and canine is like this; $1.0^{\circ}{\pm}1.3^{\circ}$, $3.0^{\circ}{\pm}1.3^{\circ}$, and $5.0^{\circ}{\pm}1.4^{\circ}$. In case of mandibular, each degree is like this; $0.6^{\circ}{\pm}1.1^{\circ}$, $1.5^{\circ}{\pm}1.1^{\circ}$, and $4.1^{\circ}{\pm}1.1^{\circ}$. Each clinical crown inclination of maxillary central incisor, lateral incisor, and canine is like this; $6.1^{\circ}{\pm}1.8^{\circ}$, $4.5^{\circ}{\pm}1.9^{\circ}$, and $-6.2^{\circ}{\pm}1.4^{\circ}$. In case of mandibular, each degree is like this; $0.3^{\circ}{\pm}1.5^{\circ}$, $0.3^{\circ}{\pm}1.8^{\circ}$, and $-7.5^{\circ}{\pm}1.8^{\circ}$. Conclusion: As the result, the mean value for clinical crown angulation and inclination can be referred to actual laboratory process. However, the mean value is different from those of the precedent study and an unsatisfied one for adopting the standard value.

• Journal of the Korean Data and Information Science Society
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• v.26 no.2
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• pp.535-545
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• 2015

In a various range of applications including hydrology, the type-I extreme value distribution has been extensively used as a probabilistic model for analyzing extreme events. In this paper, we introduce methods for estimating the scale parameter of the type-I extreme value distribution. A simulation study is performed to compare the estimators in terms of mean-squared error and bias, and the obtained results are provided.

• The Korean Journal of Applied Statistics
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• v.21 no.5
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• pp.835-843
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• 2008

In this paper, we investigate a Bayesian inference for software reliability models based on mean value functions which take the form of the mixture of beta distribution functions. The posterior simulation via the Markov chain Monte Carlo approach is used to produce estimates of posterior properties. Its applicability is illustrated with two real data sets. We compute the predictive distribution and the marginal likelihood of various models to compare the performance of them. The model comparison results show that the model based on the beta-mixture performs better than other models.

• International Journal of Reliability and Applications
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• v.7 no.2
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• pp.155-166
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• 2006

Many software reliability growth models (SRGMs) based on nonhomogeneous Poisson process (NHPP) have been developed and applied in practice. NHPP SRGMs are characterized by their mean value functions. Mean value functions are usually derived from differential equations representing the fault detection/removal process during testing. In this paper such differential equations are regarded as frameworks for generating mean value functions. Currently available frameworks are theoretically discussed with respect to capability of representing the fault detection/removal process. Then two general frameworks are proposed.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.252-252
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• 2011

Rainfall-runoff models are calibrated and validated by using a same data set such as observations. The past climate change effects the present rainfall pattern and also will effect on the future. To predict rainfall-runoff more preciously we have to consider the climate change pattern in the past, present and the future time. Thus, in this study, the climate change represents changes in mean precipitation and standard deviation in different patterns. In some river basins, there is no enough length of data for the analysis. Therefore, we have to generate the synthetic data using proper distribution for calculation of precipitation based on the observed data. In this study, Kajiyama model is used to analyze the runoff in the dry and the wet period, separately. Mean and standard deviation are used for generating precipitation from the gamma distribution. Twenty hypothetical scenarios are considered to show the climate change conditions. The mean precipitation are changed by -20%, -10%, 0%, +10% and +20% for the data generation with keeping the standard deviation constant in the wet and the dry period respectively. Similarly, the standard deviations of precipitation are changed by -20%, -10%, 0%, +10% and +20% keeping the mean value of precipitation constant for the wet and the dry period sequentially. In the wet period, when the standard deviation value varies then the mean NSE ratio is more fluctuate rather than the dry period. On the other hand, the mean NSE ratio in some extent is more fluctuate in the wet period and sometimes in the dry period, if the mean value of precipitation varies while keeping the standard deviation constant.