• Journal of Gastric Cancer
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• v.12 no.2
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• pp.88-98
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• 2012

Purpose: Local recurrence, due to residual tumor, may occur after endoscopic resection for early gastric cancer. The aims of this study are to evaluate the predictive factors for local recurrence, and suggest an appropriate follow-up biopsy strategy. Materials and Methods: We retrospectively reviewed 396 early gastric cancers from 372 consecutive patients, who underwent endoscopic resection between January 2002 and April 2008. Cumulative recurrence rates were determined by the Kaplan-Meier method, and Cox proportional hazard analysis was used to determine the risk factors for local recurrence. Results: Local recurrence at the endoscopic resection site was found in 17 cases, among the total 396 lesions, during a median follow-up period of 48 months. The 5-year cumulative local recurrence rate was 4.8%. Multivariate analyses determined that tumor involvement at the lateral resection margin [hazard ratio: 35.9; P<0.001], uncheckable lateral resection margin [hazard ratio: 16.8; P<0.001], uncheckable or involved deep resection margin [hazard ratio: 3.76; P=0.047], and piecemeal resection [hazard ratio: 3.95; P=0.007] were associated with local recurrence. If a lesion was positive for any of these risk factors, the 5-year cumulative recurrence rate was 27.0%, while local recurrence was not found in any lesion that lacked these risk factors. Most episodes of recurrence were found during the first or second follow-up endoscopic biopsy at the ulcer scar. Conclusions: Routine follow-up biopsies at the endoscopic resection site might be unnecessary in cases where an early gastric cancer lesion was endoscopically resected en bloc with tumor-free lateral and deep margins.

• Journal of Soil and Groundwater Environment
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• v.24 no.5
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• pp.11-16
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• 2019

In this study, a reliable number of soil samples for TPH fractionation was investigated in order to perform risk assessment. TPH was fractionated into volatile petroleum hydrocarbons (VPH) with three subgroups and extractable petroleum hydrocarbons (EPH) with four subgroups. At the study site, concentrations of each fraction were determined at 18 sampling points, and the 95% upper confidence limit (UCL) value was used as an exposure concentration of each fraction. And then, 5 sampling points were randomly selected out of the 18 points, and an exposure concentration was calculated. This process was repeated 30 times, and the results were compared statistically. Exposure concentrations of EPH obtained from 18 points were 99.9, 339.1, 27.3, and 85.9 mg/kg for aliphatic $C_9-C_{18}$, $C_{19}-C_{36}$, $C_{37}-C_{40}$, and aromatic $C_{11}-C_{22}$, respectively. The corresponding exposure concentrations obtained from 5 points were 139.8, 462.8, 35.1 and 119.4 mg/kg, which were significantly higher than those from 18 points results (p <0.05). Our results suggest that limited number of samples for TPH fractionation may bias estimation of exposure concentration of TPH fractions. Also, it is recommended that more than 30 samples need to be analyzed for TPH fractionation in performing risk assessment.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.287-294
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• 2017

Recently the construction project is becoming large-sized, complicated, and modernize. This has increased the uncertainty of construction risk. Therefore, studies should be followed regarding scientifically identifying the risk factors, quantifying the frequency and severity of risk factors in order to develop a model that can quantitatively evaluate and manage the risk for response the increased risk in construction. To address the problem, this study analyze the probability distribution of risk causes, the probability of occurrence and frequency of the specific risk level through Monte Carlo simulation method based on the accident data caused at construction sites. In the end, this study derives quantitative analysis by analyzing the amount of risk and probability distributions of accident causes. The results of this study will be a basis for future quantitative risk management models and risk management research.

• Journal of Construction Engineering and Project Management
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• v.6 no.2
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• pp.1-7
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• 2016

Construction in the UK is the second most dangerous industry in terms of fatal and minor injuries according to the 2014 report of HSE. The use of mobile devices such as iPad, Tablets and Smart phones on the live construction projects is also on the increase in the UK due to the 2016 - Level 2 BIM (Building Information Modelling) implementation target, set by the UK Government. Hence, the use of such devices may become a distraction from work activities on the construction sites and will cause a major risk to the end users. The subject of improving safety of BIM use is widely researched, but there is a gap in knowledge about the actual use of the mobile devices and perception of 'Site BIM', on the construction site activities. The main gap identified in the 'Site BIM' is the health and safety aspect of using such devices on the construction sites. A safer way of working with such devices needs to be identified to avoid any potential site hazards and fatalities before the widespread use of the devices are found on the construction projects. In that context, the paper is aimed to highlight the safety issues that are required to address for the successful implementation of the mobile devices for safer use of the 'Site BIM'. Questionnaire survey was used to collect the site information among construction professionals in the UK. The survey findings suggested that a proactive approach may be helpful to stop potential hazards and risks causing by the use of mobile devices and potential measures need to be identified before any injuries and incidents occur. The paper concludes that training, changing size of mobile devices and ensuring a separate induction training for 'Site BIM' tools will improve the health and safety of the end users of the mobile devices at the live construction sites.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1169-1174
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• 2015

Risk-Risk-based inspection (RBI) has been developed in order to identify risky equipments that can cause major accidents or damages in large-scale plants. This assessment evaluates the equipment's risk, categorizes their priorities based on risk level, and then determines the urgency of their maintenance or allocates maintenance resources. An earlier version of the risk-based assessment software is already installed within the equipment management system; however, the assessment is based on examination by an inspector, and the results can be influenced by his subjective judgment, rather than assessment being based on failure probability. Moreover, the system is housed within a server, which limits the inspector's work space and time, and such a system can be used only on site. In this paper, the development of independent risk-based assessment software is introduced; this software calculates the failure probability by an analytical method, and analyzes the field inspection results, as well as inspection effectiveness. It can also operate on site, since it can be installed on an independent platform, and has the ability to generate an I/O function for the field inspection results regarding the period for an optimum maintenance cycle. This program will provide useful information not only to the field users who are participating in maintenance, but also to the engineers who need to decide whether to extend the lifecycle of the power machinery or replace only specific components.

• The Journal of Engineering Geology
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• v.31 no.2
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• pp.135-148
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• 2021

Ground subsidence risk ratings obtained from the site investigation during pre-excavation stages could be changed depending on the parameters revealed during construction activities. A method of correcting the pre-excavation ground subsidence risk ratings based on the site conditions observed in the field is suggested in this study. The elevation of groundwater table during the excavation may be different from the predicted value depending on the application of waterproofing methods and construction conditions. The drastic drawdown of groundwater table during the excavation could cause ground subsidence due to soil volume decrease related to consolidation or compression of the ground, whereas the rising of groundwater table caused by the intense rainfall may result in a high potential for ground subsidence due to heaving or boiling of the excavation bottom. Excessive displacements of retaining walls or ground settlements may cause ground subsidence, which also results in a high risk of ground subsidence caused by the destruction of buried pipelines. Reevaluation of ground subsidence risk ratings is suggested considering the fluctuation of groundwater table, condition of groundwater leakage, measured ground displacements, and soil types. Finally, the ground subsidence risk rating system is improved for better evaluation by using 12 factors in 5 categories.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.150-156
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• 2018

As the types and usage of chemical increase, modern countries should protect their health and environment from the risk of hazardous chemical. Chemical accidents not only affect humans but also cause huge losses to the environment. Moreover, since its effects do not end in a short period of time, it is necessary to identify the extent of the damage and establish a prevention and response system in advance. In 2015, the Chemical Substances Management Act provided a system for assessing the impact on the people and the environment around the workplace. However, it is difficult to quantitatively evaluate the impact on environmental factors such as vegetation and aquatic, with the current hazard assessment methods. The purpose of this study is to analyze the quantitative risk of environmental receptors. This study improved the existing risk assessment formula by using the environmental vulnerability index and established the end point concentration criterion which can estimate the damage range to environmental media. To verify the results of the study, a virtual accident scenario was selected and a case study was conducted. As a result, the extent of impact on the environmental medium can be calculated, and the degree of environmental risk of the zone can be quantified through the risk analysis considering the environmental vulnerability. This study is expected to increase the reliability of the reliability of the existing risk anaylsis method beacause it is a risk analysis method that can be applied when the environmental factors are absolutely necessary and when the residents and environment are complex.

• Journal of the Korean Home Economics Association
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• v.45 no.5
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• pp.95-119
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• 2007

The purpose of this study was to investigate the shopping values(utilitarian and hedonic values) sought and the risks(economic, functional, socio-psychological, and privacy) perceived by consumers who participate in Internet auctions by determining the factors that affect their shopping values and risk perceptions. Empirical data were collected by an Internet survey of netizens who were interested in and had experience in Internet auctions. Questionnaires were distributed to the subjects through an Internet survey site and at an Internet auction cafe. A total of 300 questionnaires were analyzed. The results showed that consumers showed a slightly greater pursuit of a utilitarian value than a hedonic outcome in their Internet auction practices; however the outcomes pursued by consumers in their teens and twenties tended to be more hedonic than utilitarian. Consumers with a higher level of innovation, self-confidence in purchase, and need for information searching showed a greater pursuit of utilitarian and hedonic outcomes. The group of consumers with a higher expectation for legal protection pursued a more utilitarian outcome, whereas the group of consumers with higher influence from the reference group pursued a more hedonic outcome. The consumers showed that they perceived functional risk as boing most serious, followed by privacy risk, economic risk, and socio-psychological risk. Subjects with higher degrees of innovation, self-confidence in purchase and self-control perceived economic risk as critical. Functional risk was perceived to be highest in the group of consumers with self-control and a need for information searching, whereas socio-psychological risk was perceived to be highest in the group of consumers showing more self-control. Privacy risk was perceived to be highest in the group of consumers with a higher degree of innovation and lowest in both groups of higher and lower affection. Both economic and privacy risks were perceived to be lower in the group of lower pursuit of a hedonic outcome.

• Earthquakes and Structures
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• v.24 no.4
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• pp.275-288
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• 2023

Based on the crucial role of high-speed railway bridges (HSRBs) in the safety of high-speed railway operations, it is an important approach to mitigate earthquake hazards by proceeding with seismic risk assessments in their whole life. Bridge seismic risk assessment, which usually evaluates the seismic performance of bridges from a probabilistic perspective, provides technical support for bridge risk management. The seismic performance of bridges is greatly affected by the degradation of material properties, therefore, material damage plays a nonnegligible role in the seismic risk assessment of the bridge. The effect of material damage is not considered in most current studies on seismic risk analysis of bridges, nevertheless. To fill the gap in this area, in this paper, a nonlinear dynamic time-history analysis has been carried out by establishing OpenSees finite element model, and a seismic vulnerability analysis is carried out based on the incremental dynamic analysis (IDA) method. On this basis, combined with the site risk analysis, the time-dependent seismic risk analysis of an offshore three-span HSRB in the whole life cycle has been conducted. The results showed that the seismic risk probabilities of both components and system of the bridge increase with the service time, and their seismic risk probabilities increase significantly in the last service period due to the degradation of the material strength, which demonstrates that the impact of durability damage should be considered when evaluating the seismic performance of bridges in the design and service period.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.14-21
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• 2016

This study evaluated the applicability of stabilization of arsenic (As)-contaminated soil with iron (Fe) oxides at the former Janghang smelter site. Three Fe oxides (magnetite, goethite, and hematite) were tested as stabilizing agents to one soil sample collected from the study site. Amendment of 5% of magnetite, goethite, or hematite for one week showed the 64, 58, and 36% of reduction of the SBRC (Solubility/Bioavailability Research Consortium)-extractable (bioaccessible) As, respectively. Duration of stabilization more than one week did not show an additional reduction in SBRC-extractable As. Amendment of 5% of magnetite, which showed the highest As stabilization efficiency, was applied to 24 soil samples collected from the same site for one week, and 72% of reduction in the bioaccessible As was observed. The potential carcinogenic human health risk at the study site caused by As was $1.7{\times}10^{-5}$, which could be reduced to $8.1{\times}10^{-6}$ by the amendment of 5% magnetite for one week.