• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.1
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• pp.9-19
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• 2012

Objectives: The aim of this study is to critically review the exposure surrogates and estimates used to associate health effects in wafer fabrication workers such as spontaneous abortion and cancer, as well as to identify the limitations of retrospective exposure assessment methods Methods: Epidemiologic and exposure-assessment studies of wafer fabrication operations in the semiconductor industry were collected. Retrospective exposure-assessment methods used in cancer risk and mortality and reproductive toxicity were reviewed. Results: Eight epidemiologic papers and two reports compared cancer risk among workers in wafer fabrication facilities in the semiconductor industry with the risk of the general population. Exposure surrogates used in those cancer studies were fabrication(vs. non-fabrication), employment duration, manufacturing eras, job title (operator vs. maintenance worker) and qualitative classifications of agents without assessing specific agent or job-specific exposure. In contrast, specific operation, job title and agents were used to classify the exposure of fabrication workers, contributing to finding a significant association with spontaneous abortion (SAB). Conclusion: Further epidemiologic studies of fabrication workers using more refined exposure assessment methods are warranted in order to examine the associations between fabrication work, environment, and specific agents with cancer risk or mortality as used in SAB epidemiologic studies.

• Journal of Digestive Cancer Research
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• v.5 no.1
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• pp.32-36
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• 2017

In unresectable stage IV colorectal cancer, the role of palliative surgery is not defined clearly. The palliative surgery can be categorized into two surgeries; first, palliative primary tumor resection; second, palliative metastatectomy. Several retrospective studies reported initial palliative systemic chemotherapy in unresectable stage IV colorectal cancer did not increase primary tumor related complications such as obstruction, perforation and hemorrhage, so they insisted that primary tumor resection in asymptomatic stage IV colorectal cancer should be preserved. However, in terms of overall survival and cancer-specific or progression-free survival, several retrospective studies, especially using population-based big data, reported favored survivals in palliative primary tumor resection group. And also several studies reported that palliative metastatectomy such as liver resection without resection of lung metastasis showed better overall survivals. But those results from those studies came from retrospective studies and are likely to be affected by selection bias. Prospective randomized studies are needed to define the benefit of palliative primary tumor resection and metastatectomy in unresectable stage IV colorectal cancer. However, based on the updated evidences, the dogma that palliative primary tumor resection should be preserved in asymptomatic unresectable stage IV colorectal cancer should be questioned.

• Toxicological Research
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• v.35 no.4
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• pp.319-330
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• 2019

Adverse drug reactions (ADRs) constitute key factors in determining successful medication therapy in clinical situations. Integrative analysis of electronic medical record (EMR) data and use of proper analytical tools are requisite to conduct retrospective surveillance of clinical decisions on medications. Thus, we suggest that electronic medical recording and human genetic databases are considered together in future directions of pharmacovigilance. We analyzed EMR-based ADR studies indexed on PubMed during the period from 2005 to 2017 and retrospectively acquired 1161 (29.6%) articles describing drug-induced adverse reactions (e.g., liver, kidney, nervous system, immune system, and inflammatory responses). Of them, only 102 (8.79%) articles contained useful information to detect or predict ADRs in the context of clinical medication alerts. Since insufficiency of EMR datasets and their improper analyses may provide false warnings on clinical decision, efforts should be made to overcome possible problems on data-mining, analysis, statistics, and standardization. Thus, we address the characteristics and limitations on retrospective EMR database studies in hospital settings. Since gene expression and genetic variations among individuals impact ADRs, pharmacokinetics, and pharmacodynamics, appropriate paths for pharmacovigilance may be optimized using suitable databases available in public domain (e.g., genome-wide association studies (GWAS), non-coding RNAs, microRNAs, proteomics, and genetic variations), novel targets, and biomarkers. These efforts with new validated biomarker analyses would be of help to repurpose clinical and translational research infrastructure and ultimately future personalized therapy considering ADRs.

• Cartoon and Animation Studies
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• s.46
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• pp.107-128
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• 2017

Time is an indispensable element in creating a story. This makes comics artists use various time techniques such as prolepsis, summary, ellipsis and flashback to increase immersion in story when they create comics. This is intended to make a study on retrospective structure among various temporal structures. Retrospective structure means progress in different time sequence, and increases immersion by making readers become strained or relaxed. Besides, retrospective structure plays a role of increasing or decreasing the pace of story. The person who systematically put the retrospective structure into shape is $G\acute{e}rard$ Genette. He in his book "Narrative Discourse" classified retrospective structure into three types. These are made up of structure of analepse externes, analepse internes and analepse mixted. This makes a study on retrospective structure in narrative comics based on $G\acute{e}rard$ Genette's retrospective structure. To this end, Kang Full's webtoon was analyzed. The reason to analyze Kang Full's is that this work has storyline where things happening in parental generation is interwined with things in offspring generation, accordingly this is work suitable for studying the retrospective structure. This study is intended to examine whether three retrospective structures suggested by $G\acute{e}rard$ Genette are actually used through an analysis of , and as a result, it is intended to prove the fact that retrospective structure has an effect on immersion in work.

• Journal of Korean Society for Quality Management
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• v.22 no.4
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• pp.111-119
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• 1994

We consider logistic models based on retrospective, case-control data with stratified samples and study the Weighted Exogeneous Sampling Maximum Likelihood (WESMU) We develop a consistent estimator of the asymptotic covariance matrix of the WESML estimator.

• Safety and Health at Work
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• v.9 no.3
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• pp.249-256
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• 2018

This article aims to provide a systematic review of the exposure assessment methods used to assign wafer fabrication (fab) workers in epidemiologic cohort studies of mortality from all causes and various cancers. Epidemiologic and exposure-assessment studies of silicon wafer fab operations in the semiconductor industry were collected through an extensive literature review of articles reported until 2017. The studies found various outcomes possibly linked to fab operations, but a clear association with the chemicals in the process was not found, possibly because of exposure assessment methodology. No study used a tiered assessment approach to identify similar exposure groups that incorporated manufacturing era, facility, fab environment, operation, job and level of exposure to individual hazardous agents. Further epidemiologic studies of fab workers are warranted with more refined exposure assessment methods incorporating both operation and job title and hazardous agents to examine the associations with cancer risk or mortality.

• Journal of Preventive Medicine and Public Health
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• v.54 no.2
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• pp.153-159
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• 2021

Objectives: Life course exposure to passive smoke may predict health, but there are few validated measures. We tested the reliability and validity of a retrospective life course passive smoking questionnaire. Methods: Participants from the third follow-up of the Childhood Determinants of Adult Health study (2014-2019, ages 36-49 years) retrospectively reported mother/father/other household member smoking when living at home during childhood, including duration (years) and smoking location (never/sometimes/always inside house). The severity of exposure index (SEI; sum of mother/father/other years smoked multiplied by smoking location), cumulative years of exposure (CYE; sum of mother/father/other years), and total household smokers (THS) were derived. The reliability of retrospective passive smoking reports was examined with intraclass correlation coefficients (ICCs) using household smoking reported 34 years earlier in 1985 by participants when aged 7-15 years. Construct validity was examined by correlating retrospective passive smoking with participants' smoking in adulthood and lung function in childhood and adulthood. Results: Among 2082 participants (mean±standard deviation [SD], 45.0±2.5 years; 55.2% females), THS ranged from 0 to 5 (mean±SD, 0.9±1.0), CYE ranged from 0 to 106 (mean±SD, 10.5±13.9), and SEI ranged from 0 to 318 (mean±SD, 24.4±36.0). Retrospective measures showed moderate agreement with total household smokers reported in childhood (ICC, 0.58 to 0.62). The retrospective measures were weakly but significantly (p<0.05) correlated with participants' smoking (r=0.13 to 0.15) and lung function (r= -0.05 to -0.06). Conclusions: The retrospective passive smoking questionnaire showed reasonable reliability and validity. This measure may be useful for epidemiological studies.

• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.12-21
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• 2011

The objective of this study is to review retrospective exposure assessment methods used in wafer fabrication operations to determine whether adverse health effects including mortality or cancer incidence are related to employment in particular work activities and to recommend an appropriate approach for retrospective exposure assessment methods for epidemiological study. The goal of retrospective exposure assessment for such studies is to assign each study subject to a workgroup in such a way that differences in exposure within the workgroups are minimized, as well as to maximize the contrasts in exposure between workgroups. To reduce the misclassification of exposure and to determine if adverse health effects including mortality or cancer incidence are related to particular work activities of wafer fabrication workers, a minimum requirement of work history information on the wafer manufacturing eras, job and department at which they were exposed should be assessed. Retrospective assessment of the task that semiconductor workers performed should be conducted to determine not only the effect of a particular job on the development of adverse health effects including mortality or cancer incidence, but also to adjust for the healthy worker effect. In order to identify specific hazardous agents that may cause adverse health effects, past exposure to a specific agent or agent matrices should also be assessed.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3660-3671
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• 2022

A new methodology to derive a dose constraint for radioactive effluent from a unit of nuclear power plant (NPP) through retrospective assessment was developed to reflect operational flexibility in line with international standards. The new dose constraint can retain the safety margin between the offsite dose and the past dose constraints. As case studies, the new approach was applied to 24 Korean NPPs to address the limitations of the existing seven dose constraints that do not fully comply with current international radiation protection standards. Therefore, an effective dose constraint for Korean NPPs was proposed as no less than 0.15 mSv/y, which is comparable to the international practices and previous studies (0.05-0.3 mSv/y). Although the lower bound of the equivalent dose constraint was calculated as 0.17 mSv/y, it is not proposed in this study since the compliance with the derived effective dose constraint can prevent accompanied equivalent doses to any organs from exceeding equivalent dose limits. The new framework and the case studies are expected to contribute toward and support the revision of existing dose constraints for radioactive effluent from NPPs, ensuring better compliance with the current international safety standards as well as reflect the operational flexibility in practice.

• The Journal of Korean Medicine
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• v.31 no.1
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• pp.14-22
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• 2010

Objectives: This study aimed to evaluate any clinical research regarding asthma published by the Korean Oriental Medical Society and its sub-societies for future rigorous clinical research. Methods: Every article relevant to asthma was initially obtained from journals in the Korean Oriental Medical Society and its sub-societies by electronic search at journal web sites or manual search. Journals were limited to those registered by the Korea Research Foundation. From initial findings, two independent reviewers selected clinical articles and these articles were further analyzed separately into predefined criteria according to prospective and retrospective studies. For prospective studies, quality assessment was also conducted. Results: From 99 articles initially obtained, 19 were finally analyzed. 14 were prospective whereas 5 were retrospective. Among the prospective articles, there were no randomized controlled trials and the non-randomized studies had no control groups, with several problems of quality regarding pre-calculated study size and unbiased assessment. None of the retrospective studies described asthma diagnosis objectively and outcome measures were either non-relevant to asthma or non-validated. Conclusions: Well-designed randomized controlled studies for asthma are needed and more rigorous non-randomized controlled studies should be conducted.