• 한국수자원학회논문집
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• 제55권4호
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• pp.267-278
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• 2022

최근 국내에서는 집중호우로 인해 홍수피해가 자주 발생하고 있으며 피해규모가 증가하고 있다. 특히 도시지역은 인구와 재산이 밀집되어 있어 홍수에 매우 취약한 지역이며, 매년 하수관거 설계빈도 이상의 강우 발생 등으로 인해 내수침수 피해가 발생하고 있다. 각 지자체에서는 홍수피해 저감을 위해 기상청에서 전국적으로 동일한 강우기준에 따라 발령하는 호우특보를 통해 홍수피해 대비 및 대응을 실시하고 있다. 하지만 서울특별시는 25개 자치구가 밀집되어 있지만 자치구별로 기후, 지형, 방재 등 지역특성 및 홍수피해 특성이 상이한 실정이다. 이에 따라 본 연구에서는 서울특별시 25개 자치구를 대상으로 지역특성을 고려한 엔트로피 가중치 및 유클리드 거리를 활용하여 자치구별 홍수취약도를 산정하고, 확률강우량 및 과거 홍수피해 강우량을 기반으로 강우기준을 산정하였다. 그 결과 자치구별 2단계 강우기준은 기상청의 호우주의보 기준, 4단계 강우기준은 호우특보 기준과 크게 차이가 나지 않는 것으로 분석되었다. 또한 기후노출이 높고 적응도가 낮은 서울 북부지역이 상대적으로 홍수취약도가 높아 강우기준이 낮게 산정되었다. 이에 따라 서울 북부지역은 상대적으로 낮은 강우기준에 따라 선제적으로 홍수대응이 가능할 것으로 판단된다. 향후 지역특성 및 피해특성을 고려하여 산정된 자치구별 강우기준을 활용하여 기상예측자료의 적용성을 검토하고, 선제적인 홍수대응방안 마련을 위한 연구를 수행할 예정이다.

• 한국산업보건학회지
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• 제24권4호
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• pp.425-435
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• 2014

Objectives: This study was performed in order to establish reliable and relative selection criteria for hazardous substances requiring management(HSRM) in the Occupational Safety and Health Act in Korea. Methods: To determine the relative criteria and weight of evidence for HSRM, we analyzed the difference between the selection method of priority substances in studies by KOSHA(Korea Occupational Safety and Health Agency) and the European Union Risk Ranking Method(EURAM). In addition, 597 hazardous substances with exposure limit valueswereanalyzed and the posted health hazards classification by MOEL(Ministry of Employee and Labor), MOE(Ministry of Environment), and EU CLP(Classification, Labelling and Packaging regulation) were compared based on GHS(Globally Harmonized System of classification and labelling of chemicals) criteria. The existing HSRM(167 substances) were evaluated for suitability by the proposed criteria in this study. Results: As a result of this study, the criteria and procedures for selecting HSRM in the Occupational Safety and Health Act were arranged utilizing GHS health hazard classification results, occupational disease cases and domestic use situations. Conclusions: The applicability of the proposed criteria was proved via the evaluation of existing HSRM(167 substances). Most HSRM (161 substances) were found to correspond to a significant health effect or substantial health effect. The question of whether to include the six substances that have been found to have general health effects as HSRM would be require further research.

• 터널과지하공간
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• 제9권2호
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• pp.158-167
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• 1999

주관적이고 정성적인 암판정 방법들 때문에 굴착될 토충과암석의 물량과 이에 따른 굴착비용 산정시에 일반적으로 어려움이 많다. 그러므로 본 논문은 굴착 목적에서 서울 화강암에 대하여 객관적이고 정량적이고 쉽게 적용될 수 있는 암반판정 방법들을 제시한다. 슈미트해머와 점하중강도 시험들은 서울 화강암의 암석에 대한 일축압축강도를 정량적으로 추정하기 위한 신뢰도가 높고 손쉽게 수행할 수 있는 방법들로서 입중되었다. 또한 지표면에서 약 12m 깊이인 천부지역의 화강암 암반상태를 확인하기 위하여, 지반조건을 직접 관찰할 수 있는 수직 절취사면의 최상부에서 현장 탄성파탐사 방법이 사용되었다. 이로서 현장 탄성파탐사로서 암반 상태 및 깊이를 판단하는 신뢰성을 확인할 수 있었는데 매우 정확한 1 m의 오차만 있었다. 그러므로 비교적 천부인 서을 화강암 암반의 굴착난이도 상태를 판단하기 위하여 현장에서 절취사면에 대한 정밀 지반조사방법은 매우 유용하고 경제적인 방법으로서 고려될 수 있다.

• 한국인터넷방송통신학회논문지
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• 제14권6호
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• pp.7-12
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• 2014

SNS는 친구들의 친목과 인맥유지를 위한 순기능을 가지고 있다. 그러나 각종 기업, 개인 스패머들이 팔로잉을 통해 스팸 트윗하여 다수의 이용자들에게 노출, 불편을 끼치고 있다. 기존 연구에서 이러한 스팸 트윗에 대해 연구를 실시한경우가 있다. 그러나 정교함의 부족함과 여러 원인들로 인해 보다 정확한 분류 및 검출이 어려운 결과를 나타내었다. 본 논문에서는 스패머들의 특징, 분류기준, 분류방법에 대해 기술하였다. 또한 이러한 특징 중 링크율과 자신을 팔로워한 부류와 자신이 팔로잉한 부류와의 차이를 통하여 스패머 계정에 대한 분류기준을 제시하였다. 실험은 무작위 스팸 계정과 일반 계정을 선정하였으며 분류기준에 따라 진행하였다. 결과로 스팸 계정은 링크율 68%, 팔로워 / 팔로잉 비율은 27581.5 였고 일반 계정은 6.12%, 팔로워 / 팔로잉 비율은 1.26 였다.

• 한국산업보건학회지
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• 제24권1호
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• pp.91-102
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• 2014

Objectives: This study was performed in order to devise a procedure for supplementing the Special Management Materials in the Occupational Safety and Health Act and recommend candidate materials. The results are expected to be used as fundamental data for classification and criteria necessary to manage Special Management Materials in workplaces. Also, they are expected to be used as a basis for selecting target materials to nominate as additional Special Management Material. Methods: We investigated the selection standards for candidates and review ranges of data sources to nominate Special Management Materials. The substances classified as GHS(Globally Harmonized System of classification and labeling of chemicals) category 1A(known to have carcinogenic potential and reproductive toxicity for humans) or 1B(presumed to have carcinogenic potential and reproductive toxicity for humans) carcinogens and reproductive toxicants among the Controlled Hazardous Substances of the Regulation on Occupational Safety and Health Standards and substances with OELs(Occupational Exposure Limits) were inspected as the candidates for Special Management Materials. Conclusions: A seven-step procedure for selecting candidates to designate as Special Management Materials was suggested, including the setting of target chemicals for evaluation, classification of CMR(Carcinogens, Mutagens or Reproductive toxicants) by GHS classification and criteria, suggestion and selection of the candidates, and more. This study recommends 58 chemicals as qualified candidates to supplement the Special Management Materials.

• 대한치과의사협회지
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• 제57권3호
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• pp.149-160
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• 2019

Atrophic alveolar ridge of maxillary anterior area is commonly observed after the extraction of teeth in patients with severely compromised periodontal disease, causing difficulties with implant placement. Successful esthetics and functional implant rehabilitation rely on sufficient bone volume, adequate bone contours, and ideal implant positioning and angulation. The present case report categorized the ridge augmentation techniques using guided bone regeneration (GBR) on the maxillary anterior site by Seibert classification. Case I patient presented for implant placement in the position of tooth #11. The alveolar ridge was considered a Seibert classification I ridge defect. Simultaneous implant placement and GBR were performed. Eight months after implantation, clinical and radiological examinations were performed. Case III patient presented with discomfort due to mobility of the upper maxillary anterior site. Due to severe destruction of alveolar bone, teeth #11 and #12 were extracted. After three months, the alveolar ridge was considered a Seibert classification III ridge defect. A GBR procedure was performed; implantation was performed 6 months later. Approximately 1-year after implantation, clinical and radiological examinations were performed. During the whole treatment period, healing was uneventful without membrane exposure, severe swelling, or infection in all cases. Radiographic and clinical examinations revealed that atrophic hard tissues and buccal bone contour were restored to the acceptable levels for implant placement and esthetic restoration. In conclusion, severely resorbed alveolar ridge of the maxillary anterior area can be reconstructed with ridge augmentation using the GBR procedure so that dental implants could be successfully placed.

• Communications for Statistical Applications and Methods
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• 제23권1호
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• pp.1-20
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• 2016

Causal inference methodologies have been developed for the past decade to estimate the unconfounded effect of an exposure under several key assumptions. These assumptions include, but are not limited to, the stable unit treatment value assumption, the strong ignorability of treatment assignment assumption, and the assumption that propensity scores be bounded away from zero and one (the positivity assumption). Of these assumptions, the first two have received much attention in the literature. Yet the positivity assumption has been recently discussed in only a few papers. Propensity scores of zero or one are indicative of deterministic exposure so that causal effects cannot be defined for these subjects. Therefore, these subjects need to be removed because no comparable comparison groups can be found for such subjects. In this paper, using currently available causal inference methods, we evaluate the effect of arbitrary cutoffs in the distribution of propensity scores and the impact of those decisions on bias and efficiency. We propose a tree-based method that performs well in terms of bias reduction when the definition of positivity is based on a single confounder. This tree-based method can be easily implemented using the statistical software program, R. R code for the studies is available online.

• Safety and Health at Work
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• 제6권4호
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• pp.353-356
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• 2015

Background: In 2012, the Alaska Section of Epidemiology investigated personnel potentially exposed to a Brucella suis isolate as it transited through three laboratories. Methods: We summarize the first implementation of the United States Centers for Disease Control and Prevention 2013 revised recommendations for monitoring such exposures: (1) risk classification; (2) antimicrobial postexposure prophylaxis; (3) serologic monitoring; and (4) symptom surveillance. Results: Over 30 people were assessed for exposure and subsequently monitored for development of illness. No cases of laboratory-associated brucellosis occurred. Changes were made to gaps in laboratory biosafety practices that had been identified in the investigation. Conclusion: Achieving full compliance for the precise schedule of serologic monitoring was challenging and resource intensive for the laboratory performing testing. More refined exposure assessments could inform decision making for follow-up to maximize likelihood of detecting persons at risk while not overtaxing resources.

• Safety and Health at Work
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• 제6권4호
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• pp.279-288
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• 2015

Background: In this study, the measurement of job stress of electric overhead traveling crane operators and quantification of the effects of operator and workplace characteristics on job stress were assessed. Methods: Job stress was measured on five subscales: employee empowerment, role overload, role ambiguity, rule violation, and job hazard. The characteristics of the operators that were studied were age, experience, body weight, and body height. The workplace characteristics considered were hours of exposure, cabin type, cabin feature, and crane height. The proposed methodology included administration of a questionnaire survey to 76 electric overhead traveling crane operators followed by analysis using analysis of variance and a classification and regression tree. Results: The key findings were: (1) the five subscales can be used to measure job stress; (2) employee empowerment was the most significant factor followed by the role overload; (3) workplace characteristics contributed more towards job stress than operator's characteristics; and (4) of the workplace characteristics, crane height was the major contributor. Conclusion: The issues related to crane height and cabin feature can be fixed by providing engineering or foolproof solutions than relying on interventions related to the demographic factors.

• Safety and Health at Work
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• 제8권3호
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• pp.258-266
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• 2017

Background: Welders are exposed to many known and suspected carcinogens. An excess lung cancer risk among welders is well established, but whether this is attributable to welding fumes is unclear. Excess risks of other cancers have been suggested, but not established. We investigated welding cancer risks in the population-based Canadian Census Health and Environmental Cohort. Methods: Among 1.1 million male workers, 12,845 welders were identified using Standard Occupational Classification codes and followed through retrospective linkage of 1991 Canadian Long Form Census and Canadian Cancer Registry (1992-2010) records. Hazard ratios (HRs) were calculated using Cox proportional hazards models based on estimated risks of lung cancer, mesothelioma, and nasal, brain, stomach, kidney, and bladder cancers, and ocular melanoma. Lung cancer histological subtypes and risks by industry group and for occasional welders were examined. Some analyses restricted comparisons to blue-collar workers to minimize effects of potential confounders. Results: Among welders, elevated risks were observed for lung cancer [HR: 1.16, 95% confidence interval (CI): 1.03-1.31], mesothelioma (HR: 1.78, 95% CI: 1.01-3.18), bladder cancer (HR: 1.40, 95% CI: 1.15-1.70), and kidney cancer (HR: 1.30, 95% CI: 1.01-1.67). When restricted to blue-collar workers, lung cancer and mesothelioma risks were attenuated, while bladder and kidney cancer risks increased. Conclusion: Excess risks of lung cancer and mesothelioma may be partly attributable to factors including smoking and asbestos. Welding-specific exposures may increase bladder and kidney cancer risks, and particular sources of exposure should be investigated. Studies that are able to disentangle welding effects from smoking and asbestos exposure are needed.