• Communications for Statistical Applications and Methods
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• v.20 no.6
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• pp.455-466
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• 2013

In nested case-control studies, the most common way to make inference under a proportional hazards model is the conditional logistic approach of Thomas (1977). Inclusion probability methods are more efficient than the conditional logistic approach of Thomas; however, the epidemiology research community has not accepted the methods as a replacement of the Thomas' method. This paper promotes the inverse probability weighting method originally proposed by Samuelsen (1997) in combination with an approximate jackknife standard error that can be easily computed using existing software. Simulation studies demonstrate that this approach yields valid type 1 errors and greater powers than the conditional logistic approach in nested case-control designs across various sample sizes and magnitudes of the hazard ratios. A generalization of the method is also made to incorporate additional matching and the stratified Cox model. The proposed method is illustrated with data from a cohort of children with Wilm's tumor to study the association between histological signatures and relapses.

• Journal of Home Health Care Nursing
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• v.20 no.2
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• pp.133-140
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• 2013

Purpose: This study examined the demographic and lifestyle differences between women with osteopenia and those with normal bone mineral density (BMD) to identify risk factors for osteopenia. Method: Participants comprised 381 women age 40-64 years. Data were collected using surveys, BMD measures, and anthropometric parameters. Results: Prevalence of osteopenia was 29.1%; significant differences in age group, job, age at menarche, age at menopause, and body mass index were found between women with osteopenia and those with normal BMD. Logistic regression analysis indicated that advanced age, unemployment, lower body mass index, and lack of exercise in women were significantly associated with osteopenia. Conclusion: This study suggests the need for strategies to improve bone health and continuous cohort studies to identify risk factors.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.19-23
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• 2010

Life cycle and secondary production of Nymphs of Nemoura gemma Ham and Lee were estimated by using specimens collected from a stream in Mt. Jumbong in the central Korean peninsula. N. gemma in the study stream was univoltine. Youngest nymphs were collected in April. They appeared to grow continuously until the emergence in early spring next year. The cohort production interval for the species was estimated as 399 days. The annual secondary production (ash free dry weight) estimated by removal-summation and the size-frequency methods were 582 and $786\;mg\;m^{-2}\;yr^{-1}$, respectively. Gut content analysis showed that N. gemma was a shredder.

• Journal of Korean Dental Science
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• v.3 no.2
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• pp.34-39
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• 2010

In our daily practice, we think about the diagnosis of our patient and get into a situation wherein we have to make a clinical decision. Diagnosis and treatment come from the knowledge and experiences that each dentist should have, but sometimes, we can have doubts on our decisions. "On what evidence did I make such decision? Was that really right?" Drawing our attention these days as a possible answer to this question, evidence-based dentistry seeks to apply the best available evidence gained from the scientific method to medical decision making. To make a good decision, the strength of evidence is assessed. Specifically, randomized controlled trial, systematic review, and meta-analysis are considered the highest level of evidence; cohort study, case control study, case series, animal study, bench test, and biological plausibility follow. With the approach of evidence-based dentistry, we can make objective, scientifically sound clinical decisions. It is also patient-oriented, incorporating clinical experiences and stressing good judgments; thorough and comprehensive, it uses transparent methodology. That is the reason evidence-based dentistry can be better than other assessment methods when we make a clinical decision in modern dentistry.

• Korean Journal of Clinical Pharmacy
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• v.20 no.1
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• pp.30-38
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• 2010

This study was conducted to analyze cost-effectiveness of neoadjuvant chemotherapy for locally advanced head and neck cancer in Korean healthcare setting. We constructed a decision analytical model to estimate total costs and outcomes of paclitaxel+cisplatin (PC) or docetaxel+cisplatin+5-FU (DCF) for 2 years time horizon in 100 patient cohort with locally advanced head and neck cancer. Base analysis showed that cost savings of PC regimen were 379 million Korean Won and 231 million Korean Won in societal and payer's perspectives, respectively, compared to DCF regimen, and life saved was 0.18. PC regimen as a dominant strategy was found to be robust through sensitivity analyses.

• Communications for Statistical Applications and Methods
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• v.23 no.6
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• pp.555-562
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• 2016

Interval censored data often occur in an observational study where the subject is followed periodically. Instead of observing an exact failure time, two inspection times that include it are available. There are several methods to analyze interval censored failure time data (Sun, 2006). However, in the presence of competing risks, few methods have been suggested to estimate covariate effect on interval censored competing risk data. A sub-distribution hazard model is a commonly used regression model because it has one-to-one correspondence with a cumulative incidence function. Alternatively, Klein and Andersen (2005) proposed a pseudo-value approach that directly uses the cumulative incidence function. In this paper, we consider an extension of the pseudo-value approach into the interval censored data to estimate regression coefficients. The pseudo-values generated from the estimated cumulative incidence function then become response variables in a generalized estimating equation. Simulation studies show that the suggested method performs well in several situations and an HIV-AIDS cohort study is analyzed as a real data example.

• 대한예방의학회:학술대회논문집
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• 1998.10b
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• pp.72-73
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• 1998

• Safety and Health at Work
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• v.13 no.2
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• pp.135-140
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• 2022

Background: Coal mining is a hazardous industry. The purpose of the study is to identify the nature of occupational injuries and diseases among coal miners and to determine the factors that affect the rate of injury and duration of time loss from work. Methods: A retrospective cohort study was conducted using accepted workers' compensation claims data of 30,390 Australian coal miners between July 2003 and June 2017. Results: Musculoskeletal and fracture conditions accounted for approximately 60% of claims in all occupational groups. Cox regression analysis showed that older age and female gender were significant predictors of longer time off work. Injury types and occupations were associated with work time loss: mental health conditions, and machine operators and drivers had significantly longer durations of time off work. Conclusion: Future research can further address how these factors led to longer time off work so that coal industry regulators, employers, and healthcare providers can target interventions more effectively to these at-risk workers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.50-51
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• 2021

In this paper, in order to design an image deep learning algorithm using a Lunar New Year image, a preliminary study on the shape and shadow of the image is conducted. In order to perform image deep learning, it is necessary to identify the characteristics of the Lunar New Year image, configure an appropriate label, and proceed with the preprocessing process. Image data is a cohort photo collected by Daejeon University, and based on this, we intend to establish a goal for conducting research from the data.

• Journal of Hospice and Palliative Care
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• v.27 no.2
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• pp.82-86
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• 2024

Purpose: This study examined the quality of life (QoL) and quality of care (QoC) in inpatient hospice settings in Korea before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: Data were obtained from three institutions that participated in two prospective cohort studies. The primary outcomes measured were the QoL of patients with terminal cancer and their family caregivers (FCs), as well as the QoC as perceived by the FCs. Results: Multivariable regression analysis revealed that during the COVID-19 pandemic, both patients and FCs experienced better QoL than before the pandemic, and FCs reported a higher QoC. Conclusion: Health policymakers should consider our findings when planning for future pandemics.