• The Korean Journal of Applied Statistics
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• v.25 no.2
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• pp.261-267
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• 2012

In constructing a credit scorecard, each characteristic variable is divided into a few attributes; subsequently, weights are assigned to those attributes in a process called coarse classification. While partitioning a characteristic variable into attributes, one should determine appropriate cutpoints for the partition. In this paper, we propose a cutpoint selection method via penalization. In addition, we compare the performances of the proposed method with classification spline machine (Koo et al., 2009) on both simulated and real credit data.

• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.1-8
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• 2002

Categorizing prognostic factors is very useful for a disease diagnosis, determination of treatment and study eligibility criteria. Methods often used to categorize factors are to select a cutpoint by biological theory, by graphical examination, by the minimum p-value approach. The last method involves multiple testing, and several methods for adjusting p-values have been developed. This study determines the cutpoint of tumor size to separate patients of high risk of relapse after hepatic resection of hepatocellular carcinoma.

• The Journal of Korean Academic Society of Nursing Education
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• v.21 no.2
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• pp.215-226
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• 2015

Purpose: This study aimed to develop a self-assessment tool to evaluate program outcomes of nursing students in Korean nursing undergraduate education. Methods: The instrument development process consisted of literature review, focus group interviews, and item validation. A total of 117 items were analyzed through content validity testing. Data was gathered from 302 nursing students in Korea and analyzed using SPSS 21.0. Results: To construct validity, principal component analysis and Varimax rotation were used, and 12 factors, with a cumulative explanatory variance of 69.16%, were determined from 79 items. For internal consistency and reliability, Cronbach's ${\alpha}$ was .91. The half-split reliability results were .84 and .85, and the ROC curve showed an optimal cutpoint at 227. A five-point Likert scale was used for scoring. Conclusion: This instrument was found to have fair validity and reliability as a self-assessment tool for nursing student learning outcomes. Therefore, it can be used to evaluate program outcomes indirectly in nursing schools.

• Communications for Statistical Applications and Methods
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• v.31 no.1
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• pp.155-178
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• 2024

Regression discontinuity (RD) design is one of the most widely used methods in causal inference for estimation of treatment effect when the treatment is created by a cutpoint from the covariate of interest. There has been little attention to RD design, although it provides a very useful tool for analysis of treatment effect for censored data. In this paper, we define the causal effect for survival function in RD design when the treatment is assigned deterministically by the covariate of interest. We propose estimators of this causal effect for survival data by using transformation, which leads unbiased estimator of the survival function with local linear regression. Simulation studies show the validity of our approach. We also illustrate our proposed method using the prostate, lung, colorectal and ovarian (PLCO) dataset.

• Journal of Korean Academy of Nursing
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• v.29 no.3
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• pp.585-595
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• 1999

The purpose of this study was to examine the predictors of burnout among informal caregivers of older adults. One hundred thirty seven caregivers who had provided care to older adults over 60 years of age for more than one month were included in the study. Most of the caregivers were white (91%) and female (78%). Mean ages of the caregivers were 64 years and 78% of them were married. Seventy percent of the older adults suffered from Alzheimer and related disease. In this study, caregivers reported that they experienced burnout once a month. The scores of emotional exhaustion and reduced personal accomplishment of the caregivers were in the moderate burnout range. To examine the predictors of burnout, discriminant analysis was used. Caregivers were divided by two groups based on the sum of scores (cutpoint＝6) on three dimensions of burnout after each dimension was categorized into high(3), moderate(2), and low(1). Nine predictors were included in the analysis : Caregiver's age, employment status, Instrumental Activities of Daily Living (IADL) of the older adult, presence of dementia of the older adult, caregiver's empathy toward the older adult (emotional and cognitive), and 3 coping strategies (negative, problem-focused, cognitive reconstructioning). Caregivers who reported high burnout showed higher cognitive empathy toward the older adults than those who showed low burnout. Caregivers who experienced high burnout used negative coping more often, and cognitive reconstructioning coping and problem focused coping less often than their counterparts. Wilks' Lambda was .78 indicating that differences between the two groups were significant. Cognitive empathy and cognitive reconstructioning coping showed high standardized canonical discriminat function coefficients over .40. Discriminant function with 9 predictors correctly classified 71% of the sample. In conclusion, informal caregivers also experienced certain level of burnout. Cognitive empathy and coping strategies predicted burnout experience of the caregivers. Based on this study, nursing intervention to the informal caregivers to improve their cognitive empathy toward the older adults and to modify their coping strategies in a way to reduce burnout experience can be applied. Further research to develop effective nursing interventions for the purpose of reducing burnout experience by modifying predictors was suggested.

• Journal of agricultural medicine and community health
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• v.24 no.2
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• pp.301-314
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• 1999

To evaluate the ischemic heart disease risk factors and analysis on the its relationship between risk factors and ischemic heart disease on EKG findings in a rural area, We conducted cross-sectional health screening test for 1304 persons aged over 30 years. Blood pressure, total cholesterol, HDL cholesterol, fasting blood glucose, BMI and Waist/hip ratio, smoking data and EKG data were collected. Hypertension was classified by the sixth report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure and the cutpoints of hyperlipidemia was used National Cholesterol Education Program. The cutpoint of hyperglycemia was used National Diabetes Data Group and those for obese was 30%. The results obtained were as follows; 1. Prevalence of definitive hypertension was 41.2% in males and 41.6% in females. The prevalence of hypertension showed Increasing tendency according to age increase(p<0.05). 2. Prevalence of hyperlipidemia was 20.6% in males and 20.4% in female. In females prevalence of hyperlipidemia showed increasing tendency according to age increase(p<0.001). 3. Prevalence of obese was 23.4% in males and 28.8% in females. Upper body type was predominant in females, but lower body type was predominant in males. 4. Prevalence of hyperglycemia was 11.0% in males and 12.1% in females. The prevalence of hyperglycemia showed increasing tendency according to age increase(p<0.01). 5. The smoking rate was 63.7% in males and 2.6% in females. 6. On the EKG findings, the prevalence of myocardial ischemia and myocardial infarction was 6.7% in males and 7.5% in females. 7. The prevalence of Ischemic heart disease was higher in hypertension than normal in females and higher in obese than normal in males. In males and females the prevalence of ischemic heart disease was higher in hyperglycemia than normal and higher in upper body type than lower body type. But there is no statistical association among them.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.153-160
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• 2009

A PM10 (aerodynamic diameter${\leq}$10 ${\mu}m$) sampler is used to quantify the potential human exposure to suspended particulate matter (PM) and to comply with the governmental regulation. This study was conducted to compare and evaluate the same PM10 cutpoint and different slopes between United States Environmental Protection Agency (USEPA) PM10 sampling criterion and American Conference of Governmental Industrial Hygienists/$Comit\acute{e}$ $Europ\acute{e}en$ de Normalization/International Organization for Standardization thoracic PM10 sampling criterion through theory and experiment. Four PM10 samplers according to the USEPA criterion and one RespiCon sampler in accordance with the thoracic PM10 criterion were used in the present study. In addition, one DustTrak monitor was used to measure real time PM10 mass concentrations. All six aerosol samplers were tested in a PM generation chamber using polydisperse fly ash. Theoretical mass concentrations were calculated by applying the measured particle size distribution characteristics (geometric mean = 6.6 ${\mu}m$, geometric standard deviation = 1.9) of fly ash to each sampling criterion. The measured mass concentrations through a chamber experiment were consistent with theoretical mass concentrations in that a RespiCon sampler with the thoracic PM10 criterion collected less PM than a PM10 sampler with the USEPA criterion. The overall chamber experiment results indicated, when a PM10 sampler was used as a reference sampler, that (1) a RespiCon sampler had a normalizing factor of 1.6, meaning that this sampler underestimated an average 60% of PM10 mass sampled from a PM10 sampler, and (2) a DustTrak real-time monitor using a PM10 inlet had a calibration factor of 2.1.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.739-746
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• 2010

The purposes of this study are 1) to develop an advanced chamber system within ${\pm}10%$ of air velocity at the particulate matter (PM) collection area, 2) to research theoretical characteristics of PM10 and PM2.5 samplers, 3) to assess the performance characteristics of PM10 and PM2.5 samplers through chamber experiments. The total six one-hour experiments were conducted using the cornstarch with an mass median aerodynamic diameter (MMAD) of $20\;{\mu}m$ and an geometric standard deviation of 2.0 at the two different air velocity conditions of 0.67 m/s and 2.15 m/s in the chamber. The aerosol samplers used in the present study are one APM PM10 and one PM2.5 samplers accordance with the US federal reference methods and specially designed three mini-volume aerosol samplers (two for PM10 and one for PM2.5). The overall results indicate that PM10 and PM2.5 mini-volume samplers need correction factors of 0.25 and 0.39 respectively when APM PM samplers considered as reference samplers and there is significant difference between two mini-volume aerosol samplers when a two-way analysis of variance is tested using the measured PM10 mass concentrations. The PM10 and PM2.5 samplers with the cutpoints and slopes (PM10: $10{\pm}0.5\;{\mu}m$ and $1.5{\pm}0.1$, PM2.5: $2.5{\pm}0.2\;{\mu}m$ and $1.3{\pm}0.03$) theoretically collect the ranges of 86~114% and 64~152% considering the cornstarch characteristics used in this research. Furthermore, the calculated mass concentrations of PM samplers are higher than the ideal mass concentrations when the airborne MMADs for the cornstarch used are smaller than the cutpoints of PM samplers and the PM samplers collected less PM in another case. The chamber experiment also showed that PM10 and PM2.5 samplers had the bigger collection ranges of 37~158% and 55~149% than the theocratical calculated mass concentration ranges and the relatively similar mass concentration ranges were measured at the air velocity of 2.15 m/s comparing with the 0.67 m/s.