• Resources Recycling
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• v.27 no.3
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• pp.66-77
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• 2018

The import amount of rare metal in Korea is about 6,034 million USD, but the self-sufficiency of rare metals is about only 1%. In order to secure the stable supply of rare metals, it is necessary to operate an efficient stockpile system. In this study, we established a system to assess the adequacy of stockpiles by quantifying the risk factors of tangible and intangible risks in order to establish an efficient stockpile strategy. The model developed in this study aims to select the rare metals that need to be stockpiled first and to suggest the direction of the stockpiling policy in accordance with technological change and market change from the mid and long term viewpoint. The evaluation results derived from the model can quantitatively measure the security level of each rare metal and enable relative comparison between the rare metals using criticality matrix. Therefore, it is expected that more efficient stockpile policy will be possible if the proposed model is utilized in the future policy making.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.639-645
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• 2015

Recently, a study on the commercialization of Rope type Platform Safe Door (RPSD) technology has commenced. The study focuses on RPSD, in which a rope screen ascends to allow safe passage from the platform to the transit vehicle in aboveground stations. Currently, a pilot installation has taken in place with Daegu Metro Line 2 in MoonYang station starting from March of 2013. However, there is a need to select an appropriate pilot installation's object for the improvement in the future RPSD. An appropriate designation would correspond with the needs of the railroad corporation and as a historic railway platform with safe facilities. This study tried to usa Analytic Hierarchy Process (AHP) to determine the priority of the KTX stations to attain a list of appropriate designations for future RPSD installations by analyzing the followings: management of the facilities, operational risks, and intent of business projects. As a case study, it was applied to the evaluation of the KTX stations. For the application, it used relative measurement to calculate the weight of upper level structuring, and absolute measurement for low level structuring instead of pairwise comparisons.

• Journal of Preventive Medicine and Public Health
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• v.41 no.3
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• pp.147-152
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• 2008

Objectives : Fluoridation of drinking water is known to decrease dental caries, particularly in children. However, the effects of fluoridated water on bone over several decades are still in controversy. To assess the risk of hip fracture related to water fluoridation, we evaluated the hip fracture-related hospitalizations of the elderly between a fluoridated city and non-fluoridated cities in Korea. Methods : Cheongju as a fluoridated area and Chungju, Chuncheon, Suwon, Wonju as non-fluoridated areas were chosen for the study. We established a database of hip fracture hospitalization episode based on the claims data submitted to the Health Insurance Review Agency from January 1995 to December 2002. The hip fracture hospitalization episodes that satisfied the conditions were those that occurred in patients over 65 years old, the injuries had a hip fracture code (ICD-9 820, ICD-10 S72) and the patients were hospitalized for at least 7days. A total of 80,558 cases of hip fracture hospitalization episodes were analyzed. Results : The admission rates for hip fracture increased with the age of the men and women in both a fluoridated city and the non-fluoridated cities (p<0.01). The relative risk of hip fracture increased significantly both for men and women as their age increased. However, any difference in the hip fracture admission rates was not consistently observed between the fluoridated city and the non-fluoridated cities. Conclusions : We cannot conclude that fluoridation of drinking water increases the risk of hip fracture in the elderly.

• The Journal of Korea Robotics Society
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• v.11 no.4
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• pp.262-269
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• 2016

Flight of an autonomous unmanned aerial vehicle (UAV) generally consists of four steps; take-off, ascent, descent, and finally landing. Among them, autonomous landing is a challenging task due to high risks and reliability problem. In case the landing site where the UAV is supposed to land is moving or oscillating, the situation becomes more unpredictable and it is far more difficult than landing on a stationary site. For these reasons, the accurate and precise control is required for an autonomous landing system of a UAV on top of a moving vehicle which is rolling or oscillating while moving. In this paper, a vision-only based landing algorithm using dynamic gimbal control is proposed. The conventional camera systems which are applied to the previous studies are fixed as downward facing or forward facing. The main disadvantage of these system is a narrow field of view (FOV). By controlling the gimbal to track the target dynamically, this problem can be ameliorated. Furthermore, the system helps the UAV follow the target faster than using only a fixed camera. With the artificial tag on a landing pad, the relative position and orientation of the UAV are acquired, and those estimated poses are used for gimbal control and UAV control for safe and stable landing on a moving vehicle. The outdoor experimental results show that this vision-based algorithm performs fairly well and can be applied to real situations.

• Journal of Korean Society for Quality Management
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• v.48 no.1
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• pp.125-147
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• 2020

Purpose: This study would measure the users'perceived overall quality level of A automobile Company, which has leading market power in the domestic automobile market and analyze the causal relationships in the quality value process Model to quality capability, customer value and loyalty based on that. Especially, this study would analyze the relative impacts of the users'perceived risks appearing in the quality value process model of the formation of Quality Factors(QF), Customer Value(CV), and Customer Loyalty(CL) and analyze the moderating effect of the causal relationships among the components. Methods: For an analysis of causal relationships connected to QF, CV, and CL of the customers who purchased Auto manufacturer A's automobile users, 179 users who used within 3 years were utilized as samples for the analysis. As for QF, based on the Garvin(1988), the QF of automobiles were redesigned. For a structural equation analysis of the entire research model, the PLS(S(Partial Least Square) model was utilized. Results: As a result of an analysis, R2 of CV and CL was 0.652 for CV and 0.664 for CL, which was a very stable Goodness of fit. As a result of an analysis of the hypotheses of QF and CV, automobile performance, conformance, aesthetics, serviceability, and durability. In addition, it turned out that the perceived risk had a moderating effect on convenience, service availability, and perceived quality. Conclusion: This study found that the perceived quality risk appearing among automobile users had negative effects on the quality value process model to QF, CV and CL. In contrast, there were factors not affecting the users'quality value process in spite of the perceived risk. These factors can suggest important managerial implications in that they can be utilized as Auto manufacturer A's market-dominant strengths.

• Journal of Ginseng Research
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• v.40 no.3
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• pp.269-277
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• 2016

Background: The findings of currently available studies are not consistent with regard to the association between the risk of cancer and ginseng consumption. Therefore, we aimed to evaluate this association by conducting a meta-analysis of different studies. Methods: To systematically evaluate the effect of ginseng consumption on cancer incidence, six databases were searched, including PubMed, Ovid Technologies, Embase, The Cochrane Library, China National Knowledge Infrastructure, and Chinese VIP Information, from 1990 to 2014. Statistical analyses based on the protocol employed for a systematic review were conducted to calculate the summary relative risks (RRs) and 95% confidence intervals (CIs). Results: We identified nine studies, including five cohort studies, three case-control studies, and one randomized controlled trial, evaluating the association between ginseng consumption and cancer risk; these studies involved 7,436 cases and 334,544 participants. The data from the meta-analysis indicated a significant 16% lower risk of developing cancer in patients who consumed ginseng (RR = 0.84, 95% CI = 0.76-0.92), with evidence of heterogeneity (p = 0.0007, $I^2$ = 70%). Stratified analyses suggested that the significant heterogeneity may result from the incidence data for gastric cancer that were included in this study. Publication bias also showed the same result as the stratified analyses. In addition, subgroup analyses for four specific types of cancer (colorectal cancer, lung cancer, gastric cancer, and liver cancer) were also performed. The summary RRs for ginseng intake versus no ginseng consumption were 0.77 for lung cancer, 0.83 for gastric cancer, 0.81 for liver cancer, and 0.77 for colorectal cancer. Conclusion: The findings of this meta-analysis indicated that ginseng consumption is associated with a significantly decreased risk of cancer and that the effect is not organ specific.

• Safety and Health at Work
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• v.11 no.1
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• pp.109-117
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• 2020

Background: Ammonia and hydrogen sulfide are harmful gases generated during aerobic/anaerobic bacterial decomposition of livestock manure. We evaluated ammonia and hydrogen sulfide concentrations generated from workplaces at livestock farms and determined environmental factors influencing the gas concentrations. Methods: Five commercial swine farms and five poultry farms were selected for monitoring. Real-time monitors were used to measure the ammonia and hydrogen sulfide concentrations and environmental conditions during the manure-handling processes. Monitoring was conducted in the manure storage facility and composting facility. Information on the farm conditions was also collected through interview and walk-through survey. Results: The ammonia concentrations were significantly higher at the swine composting facilities (9.5-43.2 ppm) than at other manure-handling facilities at the swine and poultry farms, and high concentrations of hydrogen sulfide were identified during the manure agitation and mixing process at the swine manure storage facilities (6.9-19.5 ppm). At the poultry manure-handling facilities, the ammonia concentration was higher during the manure-handling processes (2.6-57.9 ppm), and very low hydrogen sulfide concentrations (0-3.4 ppm) were detected. The air temperature and relative humidity, volume of the facility, duration of manure storage, and the number of animals influenced the gas concentrations. Conclusion: A high level of hazardous gases was generated during manure handling, and some levels increased up to risk levels that can threaten workers' health and safety. Some of the farm operational factors were also found to influence the gas levels. By controlling and improving these factors, it would be possible to protect workers' safety and health from occupational risks.

• Nuclear Engineering and Technology
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• v.21 no.3
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• pp.171-185
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• 1989

On the basis of equal health hazard risk, economic assessment of nuclear was compared with that of coal for the expansion planning of electric power generation in the year 2000. In comparing health risks, the risk of coal was roughly ten times higher than that of nuclear according to various previous risk assessments of energy system. The zero risk condition can never be achievable. Therefore, only excess relative health risk of coal over nuclear was considered as social cost. The social cost of health risk was estimated by calculation of mortality and morbidity costs. Mortality cost was ＄250,000 and morbidity cost was ＄90,000 in the year 2000.(1986US＄) Through Cost/Benefit Analysis, the optimal emission standards of coal-fired power generation were predicted. These were obtained at the point of least social cost for power generation. In the year 2000, the optimal emission standard of SOx was analyzed as 165ppm for coal-fired power plants in Korea. From this assessment, economic comparison of nuclear and coal in the year 2000 showed that nuclear would be more economical than coal, whereas uncertainty of future power generation cost of nuclear would be larger than that of coal.

• The Korean Journal of Food And Nutrition
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• v.12 no.3
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• pp.279-289
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• 1999

This study was conducted to investigate the physical characteristics and risk factors for hyperchol-esterolemia (HC) in Korean. 344 adult men who took the annual health check-ups at D or J hospitals were participated in this cross-sectional study. The subjects were grouped by plasma total cholesterol level in to three groups: normal cholesterolemic (n=139) borderline hypercholesterolemic(n=93) and hypercholesterolemic (n=112) groups. The data of height weight and plasma cholesterol level were col-lected from medical records. Body circumferences(midarm, waist, hip, and thight) skinfold thicknesses (biceps, triceps, subcostal, abdomen, and suprailic), and body composition (fat mass and fat free mass) were measured. Body mass index (BMI) height/weight ratio (HWR) waist/hip circumference ratio (WHR) waist/ thigh circumference ratio (WTR) central skinfold thickenss (CSF) and peripheral skin-fold thickness were calculated. The subjects with HC had significantly higher weight BMI waist cir-cumference skinfold thickness and body fat mass than those of the normal subjects. The relative and attributable risks on HC were 1.61 and 0.17 for obesity (BMI$\geq$25) 1,30 and 0.11 for upper body obesity (WTR$\geq$1.30) and 1.54 and 0.18 for central body obesity (CSF$\geq$95.7). Plasma total cholesterol level was positively correlated with several antropometric parameters: BMI (p<0.001) weight(p<0.001) waist circumference(p<0.001) and skinfold thickness of abdomen (p<0.001) spraillic (p<0.01) triceps(p<0.01) subcostal (p<0.01) and biceps (p<0.05) In conclusion the major influencing factors to plasma cholesterol level was BMI. Among the each physical parameters the circumference of waist the skinfol-d thickness of abdomen and the percentage of body fat were closely related to plasma cholesterol level. The important risk factor for hypercholesterolemia was obesity specially upper body obesity and central body obesity.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1193-1201
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• 2016

In epidemiology or etiology, we are often interested in identifying areas of elevated risk, so called, hot spot or cluster. Many existing clustering methods only tend to a result if there exists any clustering pattern in study area. Recently, however, lots of newly introduced clustering methods can identify the location, size, and shape of clusters and test if the clusters are statistically significant as well. In this paper, one of most commonly used clustering methods, scan statistic, and its implementation SaTScan software, which is freely available, will be introduced. To exemplify the usage of SaTScan software, we used cancer data from the SEER program of National Cancer Institute of U.S.A.We aimed to help researchers and practitioners, who are interested in spatial cluster detection, using female lung cancer mortality data of the SEER program.