• Journal of the Korean Association of Geographic Information Studies
• /
• v.22 no.4
• /
• pp.181-196
• /
• 2019

Floods can be caused by a variety of factors, and the main cause of floods is the exceeding of urban drainage system or river capacity. In addition, rainfall frequently occurs that causes large watershed runoff. Since the existing methodology of preparing for flood risk map is based on hydraulic and hydrological modeling, it is difficult to analyse for a large area because it takes a long time due to the extensive data collection and complex analysis process. In order to overcome this problem, this study proposes a methodology of mapping for flood vulnerable area that considered the surface runoff mechanism. This makes it possible to reduce the time and effort required to estimate flood vulnerabilities and enable detailed analysis of large areas. The target area is Seoul, and it was confirmed that flood damage is likely to occur near selected vulnerable areas by verifying using 2×2 confusion matrix and ROC curve. By selecting and prioritizing flood vulnerable areas through the surface runoff mechanism proposed in this study, the establishment of systematic disaster prevention measures and efficient budget allocation will be possible.

• Journal of the Korean Society of Radiology
• /
• v.11 no.4
• /
• pp.227-234
• /
• 2017

This study evaluated the usefulness of the elasticity score and strain ratio in the differential diagnosis of benign and malignant nodules in thyroid elastography. We performed a retrospective analysis based on the results of fine needle aspiration cytology. The Chi-square test and the Mann-Whitney U test were used to analyze the difference between the five degrees of elasticity score and strain ratio according to the benign and malignant thyroid nodules. ROC curve analysis was used to determine the elasticity score and the best cut-off value of the strain ratio for the prediction of malignant nodules. There was a statistically significant difference (p=0.000) between the homogeneity of the elasticity score and the difference of the strain ratio between the benign and malignant nodule groups. On the ROC curve analysis, the elasticity score and the srain ratio for predicting benign and malignant nodules were determined as AUC 0.842, 0.700, cut-off value 3, 2.49 (p=0.001). Therefore, the elasticity score and strain ratio may be useful in the differential diagnosis of thyroid nodules.

• Proceedings of the Korean Statistical Society Conference
• /
• 2002.11a
• /
• pp.287-292
• /
• 2002

최근 여러 분야에서 로지스틱 회귀에 대한 필요성과 그 응용이 급증하면서 이를 분석하기 위한 통계패키지가 많이 개발되어 사용되고 있다. 이 논문에서는 자료의 유형에 따라 활용할 수 있는 여러 형태의 로지스틱 회귀모형을 간단히 살펴보고, SPSS, SAS, STATA, MINITAB과 같은 통계패키지를 사용하여 로지스틱 회귀모형에 적용할 때 각각 다룰 수 있는 범위와 그 특징에 대해 다룬다.

• Journal of radiological science and technology
• /
• v.14 no.2
• /
• pp.33-36
• /
• 1991

• Journal of Convergence for Information Technology
• /
• v.10 no.12
• /
• pp.146-155
• /
• 2020

This study was to evaluate the usefulness of gamma glutamyl transferase (GGT) as a surrogate marker predicting metabolic syndrome. 7,155 non obese men over the age of 20 were studied as subjects. The criteria for diagnosing MetS were the National Cholesterol Education Program - Third Adult Treatment Panel (NCEP-ATP III). The risk of developing MetS according to GGT was conducted logistic regression analysis, and the ROC (receiver operating characteristic) curve was obtained to confirm GGT ability to predict the risk of MetS. Regardless of age and body mass index, MetS had a 7.09 times higher risk of onset in the fourth quartile than in the first quartile of GGT (p<0.001). The AUC (area under the curve) of GGT for the diagnosis of MetS was 0.715, and the cutoff value of GGT was 40.0 U/L, the sensitivity was 65.0%, and the specificity was 70.2%. Therefore, GGT is considered to be a useful diagnostic index for diagnosing MetS.

• Tuberculosis and Respiratory Diseases
• /
• v.44 no.3
• /
• pp.611-620
• /
• 1997

Objectives : The differentiation of tuberculous effusion from the other causes of exudative pleural effusion remained difficult even with aids of biochemical analyses and pleural biopsy. As the pathophysiology of tuberculous pleural effusion is an enhanced cell mediated immunity, Adenosine deaminase(ADA) and various eytokines including Inteferon-$\gamma$, tumor necrosis factor alpha(TNF-$\alpha$) are considered as useful diagnostic tools in differentiating exudative pleural effusion. The author would like to demonstrate the diagnostic usefulness of TNF-$\alpha$ in the differentiation of exudative pleural effusion, and compared the discriminating ability of TNF-$\alpha$ with ADA. Methods : Pleural fluids obtained from 80 patients (tuberculous : 39, malignant : 31, parapneumonic : 10) with exudate pleural effusions were processed for cell counts and biochemical analysis including ADA and TNF-$\alpha$. Results : Tuberculous pleural fluid showed higher levels of ADA and TNF-$\alpha$, $48.7{\pm}32.7U/L$ and $184.1{\pm}214.2pg/mL$ than that of non-tuberculous effusion $26.0{\pm}41.3U/L$ and $44.1{\pm}114.2pg/mL$, respectively (ADA, TNF-$\alpha$, p < 0.05, p < 0.01). Receiver operating characteristics(ROC) curves were generated for ADA and TNF-$\alpha$ and the best cut-off value for adenosine deaminase and TNF-$\alpha$were considered as 30U/L and 15pg/ml, respectively. Comparing the area under the ROC curves, there was no significant difference between ADA and TNF-$\alpha$. Conclusion : For the differential diagnosis of tuberculous pleural effusion from the other causes of exudative pleural effusions, TNF-$\alpha$ as well as ADA was considered as useful diagnostic method. However adding TNF-$\alpha$ to ADA has no further diagnotic benefit than ADA alone.

• The Korean Journal of Applied Statistics
• /
• v.32 no.5
• /
• pp.653-669
• /
• 2019

The development of new media has gradually decreased the use of newspapers, which had previously occupied the largest share of media. Subscriptions have declined gradually and fell to 14 percent in 2016. This study explores the effects of Newspaper reader's characteristics on regular newspaper subscriptions. The data used for analysis was provided by the Korean Press Foundation and Media Audience Awareness Survey Data in 2016 and 2017. We considered gender, age, education, income, number of days of reading, reading time and amount of reading as the characteristics of the reader. Multiple logistic regression was fitted and interpreted to see what characteristics affect regular subscription.

• The Korean Journal of Applied Statistics
• /
• v.22 no.3
• /
• pp.569-584
• /
• 2009

Edge detection in images has been widely used in image processing system and computer vision. Morphological edge detection has used structuring elements with fixed shapes. This paper presents morphological operators with non-fixed shape kernels, or amoebas, which take into account the image contour variations to adapt their shape. Experimental results are analyzed in both qualitative analysis through visual inspection and quantitative analysis with PFOM and ROC curves. The Experiments demonstrate that these novel operators outperform classical morphological operations with a fixed, space-invariant structuring elements for edge detection applications.

• The Korean Journal of Applied Statistics
• /
• v.23 no.1
• /
• pp.13-28
• /
• 2010

Assuming a mixture distribution for credit evaluation studies, we discuss estimating threshold methods to minimize errors that default borrowers are predicted as non defaults or non defaults are regarded as defaults. A method by using statistical hypotheses tests, the most powerful test and generalized likelihood ratio test, for the probability density functions which are defined with the score random variable and the parameter space consisted of only two elements such as the default and non default states is proposed to estimate a threshold. And anther optimal thresholds to maximize classification accuracy measures of the accuracy and the true rate for ROC and CAP curves are estimated as equations related with these probability density functions. Three kinds of optimal thresholds in terms of the hypotheses testing, the accuracy and the true rate are obtained from normal random samples with various means and variances. The sums of the type I and type II errors corresponding to each optimal threshold are obtained and compared. Finally we discuss about their efficiency and derive conclusions.

• The Korean Journal of Applied Statistics
• /
• v.31 no.5
• /
• pp.573-585
• /
• 2018

In this study, we fit the logistic regression model and naïve Bayesian classifier model using 11 risk factors to predict the incidence rate probability for type 2 diabetes mellitus. We then introduce how to construct a nomogram that can help people visually understand it. We use data from the 2013-2015 Korean National Health and Nutrition Examination Survey (KNHANES). We take 3 interactions in the logistic regression model to improve the quality of the analysis and facilitate the application of the left-aligned method to the Bayesian nomogram. Finally, we compare the two nomograms and examine their utility. Then we verify the nomogram using the ROC curve.