• Communications for Statistical Applications and Methods
• /
• 제8권1호
• /
• pp.127-135
• /
• 2001

In this paper, we consider a simple method for testing the assumption of independent censoring on the basis of a Cox proportional hazards regression model with a time-dependent covariate. This method involves a two-stage sampling in which a random subset of censored observations is selected and followed-up until their true survival times are observed. Lee and Wolfe(1998) proposed an adjusted estimate of the survivor function for the dependent censoring under a proportional hazards alternative. This paper extends their result to obtain a bootstrap confidence interval for the adjusted survivor function under the dependent censoring. The proposed procedure is illustrated with an example of a clinical trial for lung cancer analysed in Lee and Wolfe(1998).

• International Journal of Advanced Culture Technology
• /
• 제9권4호
• /
• pp.61-70
• /
• 2021

At a time when children of multicultural families have begun to enter adolescence in Korea, this study examined the effects of parental support and bicultural acceptance on the career attitude maturity of multicultural adolescents. This study tried to derive the implications related to the career path of multicultural adolescents by verifying the effects of self-esteem on the relationship between parental support, bicultural acceptance, and career attitude maturity. Using the 8th Multicultural Adolescent Panel Survey data (MAPS), the relative influence of antecedent variables on career attitude maturity was confirmed by hierarchical regression analysis of the data from 1,197 respondents. Model 1 included gender and parental support, Model 2 added bicultural acceptance to Model 1, and Model 3 added self-esteem to Model 2. As a result of the study, in Model 1, women had higher career attitude maturity than men, and the more supportive their parents were, the more positive the level of career attitude maturity. The adjusted R2 of Model 1 was .058, which did not have much influence. In Model 2, gender, parental support, and bicultural acceptance had statistically significant effects on career attitude maturity, and the amount of change in F was also significant. The adjusted R2 of Model 2 was .132. In Model 3, parental support was not statistically significant, and gender, bicultural acceptance, and self-esteem had statistically significant effects on career attitude maturity. The amount of change in F was statistically significant and the adjusted R2 was .185. That is, it was confirmed that the more the women, the more the bicultural acceptance, and the higher the self-esteem, the more prepared and determined the career path. Based on the research results, the implications related to career preparation of multicultural adolescents were presented.

• 통상정보연구
• /
• 제11권2호
• /
• pp.111-126
• /
• 2009

This study analysed determinants of Foreign Direct Investment to ASEAN+ 3 member nations using panel data for which cross-sectional data are combined with time series data. The data for the analysis included the amount of FDI, GDP, and indexes of economic independence. This study collected data from six nations(Indonesia, Malaysia, Philippines, Singapore, Thailand, Vietnam) whose data were easily available, China and Japan from 2003 to 2007 and analysed them. The results are summarized as follows: Using the pooled OLS method, we found Model 2 had the highest explanatory power whose adjusted R-squared was 89.4%, which accounted for about 89% of foreign investment. Using the fixed effect model, Model 2 had the highest explanatory power whose adjusted R-squared was 96.8%, which accounted for about 97% of foreign investment. Using the probability effect model, Model 5 had the highest explanatory power, but in respect to its statistical significance, only GDP was 1% significant and the rest variables had no significance.

• ETRI Journal
• /
• 제31권2호
• /
• pp.237-239
• /
• 2009

A whole-body voxel model of a 7-year-old male volunteer was developed from 384 axial magnetic resonance images (MRIs). The MRIs were acquired with intervals of 3 mm for the entire body in a body coil. In order to reduce the MRI acquisition time for the child, the repetition and echo times under T1 weighted image were chosen to be 566 ms and 8 ms, respectively. The MRIs were classified according to 30 types of tissues with known electrical parameters. The developed voxel model was adjusted to the physical average of 7-year-old Korean boys. The body weight of the adjusted model, calculated with the mass tissue densities, is within a 6% difference from the 50th percentile weight.

• 한국정밀공학회지
• /
• 제11권2호
• /
• pp.50-64
• /
• 1994

Cutter deflections in the ball-end milling process is one of the main causes of the machining errors on a free-form surface. In order to avoid machining errors in this process, a methodology avoiding these machining errors on the free-form surfaces has been developed. In this method, feedrates in the finish cuts are adjusted for the prevention of machining errors. A model for the prediction of machining errors on the free-form surface is analytically derived as a function of feed and normal vector at the surface of contact point by the cutter. This model is applied to the dertermination of the adjusted feedrates which satisfy the machining tolerance of the surface. In the finish cuts of a simple curved surface, the suggested model is examined by the measurements of the generated machining error on this surface. And also, this surface is machined with the adjusted feedrates for the given machining tolerance. The measured machining errors on this surface are compared with the given tolerance. In this comparisons, it is shown that the predicted errors are fairly good agreement with the test results.

• 대한교통학회지
• /
• 제13권1호
• /
• pp.125-152
• /
• 1995

The purposes of this study are twofold ; (1) to investigate the accuracy of estimation power of the individual models. such as those of Highway Capacity Nanual (HCM), Korea Highway Capacity Manual (KHCM), and NationalCooperative Highway Research Program(NCHRP) Report339 ; and (2) to develop an adjusted delay model which can be applied to the signal control system in urban areas. The study is mainly focused on four subjects related to the research purposes, which are as follows ; (1) characteristecs of exsisting delay models ; (2) inherent problems in exsisting delay models : (3) validation of the proposed model by the comparison of observed delay with estimated delay :and (4) a method which can be applied to develop an appropriate delay model for actrual signal control systems by the adjusted fact of the proposed model.

• 운동영양학회지
• /
• 제25권1호
• /
• pp.35-41
• /
• 2021

[Purpose] This pilot study aimed to develop a regression model to estimate the excess post-exercise oxygen consumption (EPOC) of Korean adults using various easy-to-measure dependent variables. [Methods] The EPOC and dependent variables for its estimation (e.g., sex, age, height, weight, body mass index, fat-free mass [FFM], fat mass, % body fat, and heart rate_sum [HR_sum]) were measured in 75 healthy adults (31 males, 44 females). Statistical analysis was performed to develop an EPOC estimation regression model using the stepwise regression method. [Results] We confirmed that FFM and HR_sum were important variables in the EPOC regression models of various exercise types. The explanatory power and standard errors of estimates (SEE) for EPOC of each exercise type were as follows: the continuous exercise (CEx) regression model was 86.3% (R²) and 85.9% (adjusted R²), and the mean SEE was 11.73 kcal, interval exercise (IEx) regression model was 83.1% (R²) and 82.6% (adjusted R²), while the mean SEE was 13.68 kcal, and the accumulation of short-duration exercise (AEx) regression models was 91.3% (R²) and 91.0% (adjusted R²), while the mean SEE was 27.71 kcal. There was no significant difference between the measured EPOC using a metabolic gas analyzer and the predicted EPOC for each exercise type. [Conclusion] This pilot study developed a regression model to estimate EPOC in healthy Korean adults. The regression model was as follows: CEx = -37.128 + 1.003 × (FFM) + 0.016 × (HR_sum), IEx = -49.265 + 1.442 × (FFM) + 0.013 × (HR_sum), and AEx = -100.942 + 2.209 × (FFM) + 0.020 × (HR_sum).

• 디지털융복합연구
• /
• 제13권2호
• /
• pp.215-225
• /
• 2015

본 연구는 무릎관절치환술의 효율적 재원일수 관리를 위해 퇴원손상심층조사 자료를 이용하여 무릎관절치환술에 대한 중증도 보정 재원일수 모형을 개발하고, 이를 기반으로 무릎관절치환술의 재원일수 변이요인을 파악하고자 하였다. 수집된 퇴원손상심층조사 자료 중 무릎관절치환술 환자 4,102명을 대상으로 동반상병 보정 방법 및 데이터마이닝 기법을 이용하여 무릎관절치환술 환자에 대한 중증도 보정 재원일수 모형을 개발한 결과 CCS 동반상병 보정 방법을 이용한 의사결정나무 모형이 가장 우수하였으며, 무릎관절치환술 환자의 재원일수에 영향을 미치는 요인은 관절염 동반유무, 성, 입원경로 등으로 나타났다. 개발된 중증도 보정 모형을 기반으로 무릎관절치환술 환자의 적정 재원일수와 실제 재원일수의 차이를 파악한 결과 진료비지불방법, 병상규모, 의료기관 소재지 모두 통계적으로 유의한 차이가 있었다. 따라서 무릎관절치환술 환자의 재원일수 변이를 줄이고 효율적으로 관리하기 위해서는 과잉 진료에 대한 모니터링 등에 정책적 방안 마련이 필요하다.

• 보건의료산업학회지
• /
• 제9권2호
• /
• pp.81-88
• /
• 2015

The purpose of this study was to compare the risk-adjusted in-hospital mortality for craniotomies between logistic regression and multilevel analysis. By using patient sample data from the Health Insurance Review & Assessment Service, in-patients with a craniotomy were selected as the survey target. The sample data were collected from a total number of 2,335 patients from 90 hospitals. The sample data were analyzed with SAS 9.3. From the results of the existing logistic regression analysis and multilevel analysis, the values from the multilevel analysis represented a better model than that of logistic regression. The intra-class correlation (ICC) was 18.0%. It was found that risk-adjusted in-hospital mortality for craniotomies may vary in every hospital. The agreement by kappa coefficient between the two methods was good for the risk-adjusted in-hospital mortality for craniotomies, but the factors influencing the outcome for that were different.

• 한국산학기술학회논문지
• /
• 제12권6호
• /
• pp.2668-2676
• /
• 2011

손상입원환자의 재원일수 변이요인을 분석하기 위해 질병관리본부의 퇴원손상환자 자료를 이용하여 재원일수 중증도 보정모형을 개발하였다. 이 모형을 적용, 보정값을 산출하고 실측값과의 차이를 이용하여 재원일수를 표준화한 후 재원일수의 변이를 분석하였다. 입원손상환자의 중증도 보정 재원일수에 영향을 미치는 주요 요인은 중증도, 수술유무, 연령, 손상기전, 입원경로 등으로 나타났다. 의사결정나무 모형에 의하여 재원일수의 보정값을 산출하여 실측값과의 차이를 분석한 결과 병원규모(병상수)별, 보험유형별, 기관 소재지별로 통계적으로 유의한 차이가 있는 것으로 나타났다. 따라서 재원일수의 변이를 줄이기 위해 국가차원에서 진료행위프로토콜을 개발하여 의료기관에서 이를 활용하도록 유도하고, 더 나아가 이를 체계적으로 평가하여 지속적으로 노력하여야 할 것이다.