• Tuberculosis and Respiratory Diseases
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• v.47 no.4
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• pp.498-506
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• 1999

Background : The causes of solitary pulmonary nodule are many, but the main concern is whether the nodule is benign or malignant. Because a solitary pulmonary nodule is the initial manifestation of the majority of lung cancer, accurate clinical and radiologic interpretation is important. Bayes' theorem is a simple method of combining clinical and radiologic findings to estimate the probability that a nodule in an individual patients is malignant. We estimated the probability of malignancy of solitary pulmonary nodules with a specific combination of features by Bayesian approach. Method : One hundred and eighty patients with solitary pulmonary nodules were identified from multi-center analysis. The hospital records of these patients were reviewed and patient age, smoking history, original radiologic findings, and diagnosis of the solitary pulmonary nodules were recorded. The diagnosis of solitary pulmonary nodule was established pathologically in all patients. We used to Bayes' theorem to devise a simple scheme for estimating the likelihood that a solitary pulmonary nodule is malignant based on radiological and clinical characteristics. Results : In patients characteristics, the probability of malignancy increases with advancing age, peaking in patients older than 66 year of age(LR : 3.64), and higher in patients with smoking history more than 46 pack years(LR : 8.38). In radiological features, the likelihood ratios were increased with increasing size of the nodule and nodule with lobulated or spiculated margin. Conclusion : In conclusion, the likelihood ratios of malignancy may improve the accuracy of the probability of malignancy, and can be a guide of management of solitary pulmonary nodule.

• Journal of KIISE:Software and Applications
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• v.30 no.3_4
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• pp.239-250
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• 2003

Recent recommender system user a method of combining collaborative filtering system and content based filtering system in order to slove the problem of the Sparsity and First-Rater in collaborative filtering system. In this paper, to make up for the prediction accuracy in hybrid Recommender system, the harmonic mean weight(CBCF_harmonic_mean) is used for calculating the user similarity weight. After setting up the threshold as 45 considering the performance of content based filtering, we apply significance weight of n/45 to user similarity weight. To estimate the performance of the proposed method, it if compared with that of combing both the existing collaborative filtering system and the content- based filtering system. As a result, it confirms that the suggested method is efficient at improving the prediction accuracy as solving problems of the exiting collaborative filtering system.

• Journal of Preventive Medicine and Public Health
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• v.40 no.3
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• pp.233-238
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• 2007

Objectives : We aimed to assess the relationship between long-term exposure to air pollution and lung cancer in the Republic of Korea. Methods : Using the Annual Report of Ambient Air Quality in Korea, Annual Report of National Cancer Registration, and Annual Report on the Cause of Death Statistics, we calculated the standardized mortality ratio (SMR) and standardized incidence ratio (SIR) of lung cancer for both sexes in 74 areas from 7 Korean metropolitan cities. We performed random intercept, Poisson regression using empirical Bayes method. Results : Both SMRs and SIRs in the 7 metropolitan cities were higher in women than in men. Mean SIRs were 99.0 for males and 107.0 for females. The association between $PM_{10}$ and lung cancer risk differed according to gender. $PM_{10}$ was not associated with the risk of lung cancer in males, but both incidence and mortality of lung cancer were positively associated with $PM_{10}$ in females. The estimated percentage increases in the rate of female lung cancer mortality and incidence were 27% and 65% at the highest $PM_{10}$ category $({\geq}70\;{\mu}g/m^3)$, compared to the referent category $({\geq}50\;{\mu}g/m^3)$. Conclusions : Long-term exposure to $PM_{10}$ was significantly associated with female lung cancer incidence in 7 Korean metropolitan cities. Further study is undergoing to estimate the relative risk of $PM_{10}$ using multi-level analysis for controlling individual and regional confounders such as smoking and socioeconomic position.

• The Korean Journal of Pain
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• v.34 no.4
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• pp.509-533
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• 2021

Background: Postherpetic neuralgia (PHN) is a refractory complication of herpes zoster (HZ). To prevent PHN, various strategies have been aggressively adopted. However, the efficacy of these strategies remains controversial. Therefore, we aimed to estimate the relative efficacy of various strategies used in clinical practice for preventing PHN using a network meta-analysis (NMA). Methods: We performed a systematic and comprehensive search to identify all randomized controlled trials. The primary outcome was the incidence of PHN at 3 months after acute HZ. We performed both frequentist and Bayesian NMA and used the surface under the cumulative ranking curve (SUCRA) values to rank the interventions evaluated. Results: In total, 39 studies were included in the systematic review and NMA. According to the SUCRA value, the incidence of PHN was lower in the order of continuous epidural block with local anesthetics and steroids (EPI-LSE), antiviral agents with subcutaneous injection of local anesthetics and steroids (AV + sLS), antiviral agents with intracutaenous injection of local anesthetics and steroids (AV + iLS) at 3 months after acute HZ. EPI-LSE, AV + sLS and AV + iLS were also effective in preventing PHN at 1 month after acute HZ. And paravertebral block combined with antiviral and antiepileptic agents was effective in preventing PHN at 1, 3, and 6 months. Conclusions: The continuous epidural block with local anesthetics and steroid, antiviral agents with intracutaneous or subcutaneous injection of local anesthetics and a steroid, and paravertebral block combined with antiviral and antiepileptic agents are effective in preventing PHN.

• The Korean Journal of Applied Statistics
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• v.35 no.2
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• pp.217-227
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• 2022

Quantile regression is widely used in many fields based on the advantage of providing an efficient tool for examining complex information latent in variables. However, modern large-scale and high-dimensional data makes it very difficult to estimate the quantile regression model due to limitations in terms of computation time and storage space. Divide-and-conquer is a technique that divide the entire data into several sub-datasets that are easy to calculate and then reconstruct the estimates of the entire data using only the summary statistics in each sub-datasets. In this paper, we studied on a variable selection method using Bayes information criteria by applying the divide-and-conquer technique to the penalized quantile regression. When the number of sub-datasets is properly selected, the proposed method is efficient in terms of computational speed, providing consistent results in terms of variable selection as long as classical quantile regression estimates calculated with the entire data. The advantages of the proposed method were confirmed through simulation data and real data analysis.

• Journal of Korea Water Resources Association
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• v.46 no.1
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• pp.13-24
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• 2013

The main objective of this study was to develop a new regional frequency analysis model based on hierarchical Bayesian model that allows us to better estimate and quantify model parameters as well as their associated uncertainties. A Monte-carlo experiment procedure has been set up to verify the proposed regional frequency analysis. It was found that the proposed hierarchical Bayesian model based regional frequency analysis outperformed the existing L-moment based regional frequency analysis in terms of reducing biases associated with the model parameters. Especially, the bias is remarkably decreased with increasing return period. The proposed model was applied to six weather stations in Jeollabuk-do, and compared with the existing L-moment approach. This study also provided shrinkage process of the model parameters that is a typical behavior in hierarchical Bayes models. The results of case study show that the proposed model has the potential to obtain reliable estimates of the parameters and quantitatively provide their uncertainties.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1249-1258
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• 2015

DGAT1(diacylglycerol O-acyltransferase1) gene is well known as a major gene of milk production in dairy cattle. This study was conducted to investigate how the DGAT1 gene effect on milk yield was appeared from the genome wide association (GWA) using high density whole genome SNP chip. The data set used in this study consisted of 353 Korean Holstein sires with 50k SNP genotypes and deregressed estimated breeding values of milk yield. After quality control 41,051 SNPs were selected and locations on chromosome were mapped using UMD 3.1. Bayesian regression of BayesB method (pi=0.99) was used to estimate the SNP effects and genomic breeding values. Percentages of variance explained by 1 Mb non-overlapping windows were calculated to detect the QTL region. As the result of this study, top 1 and 3 of 2,516 windows were seen around DGAT1 gene region and 0.51% and 0.48% of genetic variance were explained by these two windows. Although SNPs on the DGAT1 gene region are excluded in commercial 50k SNP chip, the effect of DGAT1 gene seem to be reflected on GWA by the SNPs which are in linkage disequilibrium with DGAT1 gene.

• Journal of the Korean Data and Information Science Society
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• v.24 no.4
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• pp.689-699
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• 2013

This paper studies the partial credibility application method by assuming the empirical prior or noninformative prior informations in auto insurnace business where intensive rating segmentation is expanded because of premium competition. Expanding of rating factor segmetation brings the increase of pricing cells, as a result, the number of cells for partial credibility application will increase correspondingly. This study is trying to suggest more accurate estimation method by considering the Bayesian framework. By using empirically well-known or noninformative information, inducing the proper posterior distribution and applying the Bayes estimate which is minimizing the error loss into the credibility method, we will show the advantage of Bayesian inference by comparison with current approaches. The comparison is implemented with square root rule which is a widely accepted method in insurance business. The convergence level towarding to the true risk will be compared among various approaches. This study introduces the alternative way of redcuing the error to the auto insurance business fields in need of various methods because of more segmentations.

• The Korean Journal of Applied Statistics
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• v.26 no.2
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• pp.267-280
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• 2013

College tuition is a significant economic, social, and political issue in Korea. We conduct a Bayesian analysis of a hierarchical model to address the factors related to college tuition based on a survey data collected by Statistics Korea. A binary response variable is selected depending on if more than 70% of tuition costs are supported by parents, and a hierarchical Probit model is constructed with areas as groups. A set of explanatory variables is selected from a factor analysis of available variables in the survey. A Markov chain Monte Carlo algorithm is used to estimate parameters. From the analysis results, income and stress are significantly related to college tuition support from parents. Parents with high income tend to support children's college tuition and students with parents' financial support tend to be mentally less stressed; subsequently, this shows that the economic status of parents significantly affects the mental health of college students. Gender, a healthy life style, and college satisfaction are not significant factors. Comparing areas in terms of the degrees of correlation between stress/income and tuition support from parents, students in Kangwon-do are the most mentally stressed when parents' support is limited; in addition, the positive correlation between parents support and income is stronger in big cities compared to provincial areas.

• Journal of Chest Surgery
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• v.22 no.3
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• pp.425-435
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• 1989

The solitary pulmonary nodule is considered as a round or ovoid lesion with sharp, circumscribed borders, surrounded by normal appearing lung parenchyme on all sides, and found on a simple chest X-ray without any particular symptoms or signs. There is a wide spectrum of pathologic conditions in the solitary pulmonary nodules prove to be malignant tumors, either primary or metastatic. Most Benign granulomas and other benign conditions can also be seen as solitary nodules. The resection of solitary malignant nodules results in a surprisingly high 5-year survival rate. On the contrary, most benign nodules do not need to be resected and a period of prolonged observation and nonsurgical management is usually indicated. Therefore, the best approach to the controversial management of solitary pulmonary nodules depends on finding factors affecting the probability of malignancy. In this article, clinical records and chest roentgenographies of 60 patients operated on over the past 8 years at the Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital were reviewed. There were 15 malignant nodules and 45 benign nodules and the prevalence of malignancy was 25%. The most common pathologic entity was tuberculoma [21 cases]. The mean age was 55.5*9.6 years in the malignant group, 45.8>12.5 years in the benign group and there was a significant statistical difference between the two groups [P < 0.05]. The malignant ratio in each age group increased with advancing age. The average smoking amount was 35.6*12.9 cigarettes per day in malignant smokers, 20.9* 12.0 cigarettes per day in benign smokers, and there was a significant statistical difference between the two groups [p< 0.05]. The malignant ratio also increased with the increasing smoking amount. Comparing the appearance of the nodule on chest films, 6 calcifications and 7 cavitations were found only in benign nodules, not in malignant nodules. Therefore, calcification and cavitation can be considered as preferential findings for benignity. Previous cancer history was also a significant factor deciding the prognosis of the nodule [p< 0.05]. The average diameter on chest X-ray was 3.07*0.82 cm in malignant nodules, 3.25*1.04 cm in benign nodules and there was no significant statistical difference between the two groups [p< 0.05]. The author used Bayes theorem to develop a simple method for combining individual clinical or radiological factors of patients with solitary nodules into an overall estimate of the probability that the nodule is malignant. In conclusion, patient age, smoking amount, appearance of nodule on chest film such as calcification and cavitation, and previous cancer history were found to be strongly associated with malignancy, but size of nodule was not associated with malignancy. Since these prognostic factors have been found retrospectively, prospective controlled studies are needed to determine whether these factors have really prognostic significance.