• Structural Engineering and Mechanics
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• 제29권6호
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• pp.689-707
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• 2008

This study presents a method to evaluate the seismic risk of an extradosed bridge with seismic isolators of lead rubber bearings (LRBs), and also to show the effectiveness of the LRB isolators on the extradosed bridge, which is one of the relatively flexible and lightly damped structures in terms of seismic risk. Initially, the seismic vulnerability of a structure is evaluated, and then the seismic hazard of a specific site is rated using an earthquake data set and seismic hazard maps in Korea. Then, the seismic risk of the structure is assessed. The nonlinear seismic analyses are carried out to consider plastic deformation of bridge columns and the nonlinear characteristics of soil foundation. To describe the nonlinear behaviour of a column, the ductility demand is adopted, and the moment-curvature relation of a column is assumed to be bilinear hysteretic. The fragility curves are represented as a log-normal distribution function for column damage, movement of superstructure, and cable yielding. And the seismic hazard at a specific site is estimated using the available seismic hazard maps. The results show that in seismically-isolated extradosed bridges under earthquakes, the effectiveness of the isolators is much more noticeable in the columns than the cables and girders.

• Earthquakes and Structures
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• 제19권6호
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• pp.471-484
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• 2020

Previous earthquakes show that, structural safety evaluations should include the evaluation of nonstructural components. Failure of nonstructural components can affect the operational capacity of critical facilities, such as hospitals and fire stations, which can cause an increase in number of deaths. Additionally, failure of nonstructural components may result in economic, architectural, and historical losses of community. Accelerations and random vibrations must be under the predefined limitations in structures with high technological equipment, data centers in this case. Failure of server equipment and anchored server racks are investigated in this study. A probabilistic study is completed for a low-rise rigid sample structure. The structure is investigated in two versions, (i) conventional fixed-based structure and (ii) with a base isolation system. Seismic hazard assessment is completed for the selected site. Monte Carlo simulations are generated with selected parameters. Uncertainties in both structural parameters and mechanical properties of isolation system are included in simulations. Anchorage failure and vibration failures are investigated. Different methods to generate fragility curves are used. The site-specific annual hazard curve is used to generate risk curves for two different structures. A risk matrix is proposed for the design of data centers. Results show that base isolation systems reduce the failure probability significantly in higher floors. It was also understood that, base isolation systems are highly sensitive to earthquake characteristics rather than variability in structural and mechanical properties, in terms of accelerations. Another outcome is that code-provided anchorage failure limitations are more vulnerable than the random vibration failure limitations of server equipment.

• Toxicological Research
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• 제13권1_2호
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• pp.49-54
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• 1997

PCBs are classified as B2 (Probable human carcinogen) based on the induction of hepatocellular carcinomas in rats and mice from IRIS (Integrated Risk Information System). About 20 years ago, PCBs were phased out for electrical use in Korea, but PCBs were continuously used in the other field. Lately, there has been increasing concern on possible effects of contaminated soil to the other environment and human health. The purpose of this study is to determine PCBs level in soil at some site and to assess the human exposure doses according to exposure routes for people living within sites which expected to be exposed to PCBs. Pollution level of PCBs on the site was monitored using gas liquid chromatography. To assess the transport of PCBs in soil to plant and to air, various transfer factors(diffusion coefficient, bioconcentration factor etc.) were considered in simple calculations. To calculate the residential exposure doses by routes, some equations were considered using assumption value, which define inhalation, ingestion (soil, plant) and derreal uptake pathway. Computated results will be used as risk assessment information for human health evaluation on contaminated soil.

• Journal of Korean Neurosurgical Society
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• 제61권5호
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• pp.645-652
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• 2018

Objective : This study aimed to investigate the rates, types, and risk factors of surgical site infection (SSI) following intracranial neurosurgical procedures evaluated by a Korean SSI surveillance system. Methods : This was a prospective observational study of patients who underwent neurosurgical procedures at 29 hospitals in South Korea from January 2017 to June 2017. The procedures included craniectomy, craniotomy, cranioplasty, burr hole, and ventriculoperitoneal shunt. Univariate and multivariate logistic regression analyses were performed. Results : Of the 1576 cases included, 30 showed infection, for an overall SSI rate of 1.9%. Organ/space infection was the most common, found in 21 out of the 30 cases (70%). Staphylococcus aureus was the most common (41%) of all bacteria, and Serratia marcescens (12%) was the most common among gram-negative bacteria. In univariate analyses, the p-values for age, preoperative hospital stay duration, and over T-hour were <0.2. In a multivariate analysis of these variables, only preoperative hospital stay was significantly associated with the incidence of SSI (p<0.001), whereas age and over T-hour showed a tendency to increase the risk of SSI (p=0.09 and 0.06). Conclusion : Surveillance systems play important roles in the accurate analysis of SSI. The incidence of SSI after neurosurgical procedures assessed by a national surveillance system was 1.9%. Future studies will provide clinically useful results for SSI when data are accumulated.

• 한국가스학회지
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• 제21권3호
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• pp.9-16
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• 2017

위험물을 취급하는 사업장에서 인근에 미치는 영향을 평가할 때 독성물질의 누출은 가장 관심있는 분야중의 하나이다. 대표적인 시설로서 염산 생산시설을 선정하여 공정정보로부터 사고 시나리오를 선정하고 독성물질 누출시 사업장외로 영향을 미치는 사고 시나리오를 선정하여 환경부의 지침에 따라서 평가하였다. ALOHA를 활용하여서 최악의 사고 시나리오를 비롯한 사고 시나리오를 평가하였으며 이들의 사고시 피해완화대책도 살펴보았다. 평가결과 염산생산시설은 현재의 안전조치가 충분하여서 추가의 개선대책이 필요하지 않은 것으로 판명되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권3호
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• pp.13-23
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• 2019

The purpose of this study is to suggest conceptual models based on finite numerical method that can be used to assess contaminant transport through subsurface and estimate exposed concentration at contaminated site. This study tested various assumptions of the numerical models for contaminant transport in unsaturated and saturated zones to simulate the pathways to the human exposal point. For this purpose, models for seven possible scenarios of contaminant transport were simulated using the numerical code MODFLOW and MT3D. The simulation results that showed different peak concentrations and travel times were compared. In conclusion, the potential utility of the numerical models in the site specific risk analysis suggested as well as future research ramifications.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.189-190
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• 2019

Designers and builders are omitting structural design and relying on workers' experience, due to the lack of awareness of the importance of scaffolding in domestic construction sites, and there is a high probability of collapsing accidents such as inappropriate wall joint installation and non-compliance with work procedures. Therefore, risk factors were analyzed in detail and major risk factors were derived from opinions of site managers and scaffolding experts in this study.

• 대한안전경영과학회지
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• 제12권3호
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• pp.1-11
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• 2010

Establishing a framework, to explain the path to safety accidents considering major safety management factors such as physical conditions including on-site activities and workplace, as well as human factors as to labor, supervisors, or managers, would be effective as the basis to control project's risks by preventing disasters. Therefore, this study aimed to clarify the mechanism in safety management and disaster occurrence. In order to accomplish the purpose, it identified and classified the factors related to accidents, reviewed the causal relationships among them, and suggested the influence diagram. The results of this research are expected to contribute to reinforcing the preventive management, and facilitating the development of integrated site control system based on safety risks.

• 한국해양학회지:바다
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• 제21권4호
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• pp.125-133
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• 2016

본 연구는 통영연안의 오염 현황을 파악하기 위하여 표층퇴적물의 유기물 분포 특성, 미량금속의 공간적인 분포 특성과 오염도 및 생태계 위해성평가를 하였다. 총질소(Total nitrogen, TN), 총유기탄소(Total organic carbon, TOC)와 산 휘발성 황화물(Acid volatile sulfide, AVS)은 협수로에 위치한 정점 35-38에서 높은 농도를 나타내었다. Cd, Cr, Ni, Co, Hg, Zn의 공간적 분포양상은 유사하였으며, 이와 달리 Cu는 협수로에서 높은 농도를 나타내었다. 미량금속 원소의 오염도를 농축계수(Enrichment Factor, EF)로 평가한 결과, Cd이 모든 정점에서 오염되지 않은 상태(No enrichment), Pb, Cr, Ni, Co, Zn, Hg이 약간 오염상태(Minor enrichment), Cu가 약간~중간 오염상태(minor-moderate enrichment)의 오염도를 나타냈다. 미량금속에 의한 생태위해성 수준은 오비도와 미륵도 사이의 협수로 정점에서 국지적으로 생태계에 잠재적 위해성이 있는 것으로 나타났다.

• 한국환경과학회지
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• 제19권6호
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• pp.671-680
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• 2010

The present study evaluated residential exposure to atmospheric formaldehyde and acetaldehyde according to distance from the a dyeing industry complex (DIC). This purpose was achieved by measuring concurrently the outdoor air concentrations in residences near the DIC and a certain distance away, plus the outdoor air concentrations at two industrial areas within the DIC boundary. Formaldehyde concentrations (median values of 24.3 and $22.5{mu}g/m^3$ in IS1 and IS2, respectively) were higher than acetaldehyde concentrations (median values of 7.4 and $7.3{mu}g/m^3$ in IS1 and IS2, respectively) at both sites. However, there was no significant difference in the industrial outdoor air concentrations of both formaldehyde and acetaldehyde between the two sites. In addition, the median formaldehyde concentration from the residential site near the DIC (RS1) was about 1.5 times higher than that from the residential site far away from the DIC(RS2), and the median acetaldehyde concentration from RS1 was about 1.3 times higher than that from RS2. It is noteworthy that the mean or median risk as well as these maximum risks are well above the USEPA's permissible risk level of $10^{-6}$ from environmental exposure. This suggests that appropriate management for formaldehyde and acetaldehyde is necessary in order to decrease risk of the residents of study areas, regardless of the distance from the DIC.