• 한국안전학회지
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• 제26권3호
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• pp.15-22
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• 2011

Explosion and fire cause about 30 reported industrial major accidents a year by ignition source which discharge of electrostatic generated to flammable gas, vapor, dust and mixtures. It brings economically and humanly very large loss that accident was caused by fire and explosion from electrostatic discharge. Thus, it is very important that electrostatic discharge energy is to be control below not to be igniting flammable mixtures. There are two kinds of analysis model for electrostatic discharge, human body model and machine model. Human body model is available the parameter of human's electrical equivalent that capacitance is 100 pF, resistance is $1.5k{\Omega}$. To simulate and visualize the electrostatic discharge from human body need a very expensive and high voltage simulator. In this paper, we measured the value of capacitance and resistance concerned with test materials and sizing of specimen and the value of charged voltage concerned with test specimen and distance to develop an electrostatic charge/discharge simulating tool for teaching with which concerned industrial employee and students. The result of experiments, we conformed that the minimum ignition energy of methane-oxygen mixtures meets well the equation $W=1/2CV^2$, and found out that the insulating material and sizing of equivalent value having human body mode are the poly ethylene of 200 mm and 300 mm of diameter. Developed electrostatic charge/discharge simulating tool has many merits; simple mechanism, low cost, no need of electric power and so on.

• 한국안전학회지
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• 제23권6호
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• pp.14-20
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• 2008

A large number of accidents have been occurred in the domestic shipbuilding industry. Its number of accidents is approximately twice than that of manufacturing industry and three times larger than that of whole industry in general. There are several reasons that make it hard to control the accidents. First, it is because the shipbuilding industry is composed of many subcontractors who may need improvement in safety education and safety management. Second, the shipyard environments are exposed to lots of hazards such as high elevation works, isolated workspaces, heavyweight and huge structures/components. Last, the shipbuilding industry has grown too rapidly in a short period. For that reason, the safety management standards and safety consciousness could not catch up the speed of its development. In this study, it is suggested to use a more efficient and easier way to conduct safety management using a web-based safety management system for the shipbuilding industry. This system is composed of four main parts, which is available for self-auditing with legal support. Those are checklists based safety and health evaluation, safety inspection, user shared accident database and user shared bulletin board. It is expected that this system can help us to reduce risks in the shipbuilding industry considerably.

• Journal of Preventive Medicine and Public Health
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• 제35권4호
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• pp.351-358
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• 2002

Objective : To evaluate the relationship between physical activity and the risk of hip fracture in the elderly Korean people. Methods : The study population was a Physical Activity Subcohort (n=8,908) extracted from the Korean Elderly Pharmacoepidemiological Cohort (KEPEC). Physical activity information was obtained from a mailed questionnaire surveys. The outcome data was collected from claims data gathered between Jan. 1993 and Dec. 1998. A hospital survey relating to potential cases was conducted to confirm the final diagnoses. The abstracted data was reviewed by a medical doctor before the final diagnoses were confirmed. A mailing questionnaire survey was performed to obtain information on potentially confounding variables, including alcohol intake, smoking habits, weight, height and postmenopausal duration. There were 79 confirmed cases hospitalized due to hip fractures between Jan. 1993 and Dec. 1998. Relative risk of physical activity scores on the hip fracture, and their 95% confidence intervals, were estimated by a Cox's proportional hazard model using SAS for Windows ver.6.12. Results : Compared to the reference group, the adjusted relative risk of hip fracture associated with the most physical active category: after controlling for age, weight and alcohol intake in the males, and for weight, alcohol intake and postmenopausal duration in the females, were 1.04 (95% CI=0.35-3.06) and 0.f4 (95% CI=0.26-0.77), respectively. Conclusions : Physical activity may protect elderly women from hip fracture.

• Journal of Preventive Medicine and Public Health
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• 제35권4호
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• pp.305-312
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• 2002

Objectives : The reproductive history of women has been suggested to have a possible influence on the risk of osteoporotic fractures. The purpose of this study was to assess the association between reproductive history and hip fractures in the elderly women. Methods : The study subjects were drawn from women members of the Korean Elderly Pharmacoepidemiologic Cohort (KEPEC), aged 65 years or over, whose reproductive histories were available, and who were beneficiaries of the Korea Medical Insurance Corporation (KMIC) in 1993 and lived in Busan city, Korea. The information on reproductive histories, and possible confounders, were collected from mailed questionnaires. Potential hip fracture cases were collected from the claims data obtained between 1993 and 1998, with a hospital survey conducted to confirm the final diagnoses. Rate ratios and their 95% confidence intervals, were calculated using a Cox's proportional hazard model. Results : Following up 5,215 women for 6 years, 51 cases were confirmed with hip fractures. When adjusted for age, weight and physical activity, the rate ratio of hip fractures in women who had given birth three or more times was 0.56 (95% CI: 0.25-1.25), compared with those who had given birth two or less times. When adjusted for age, number of births, weight and physical activity, the rate ratio in women who first gave birth when younger than 22 years was 0.60 (95% CI: 0.34-1.08) compared with those who had giving birth at 22 years or older. Conclusions : According to these findings, an early age when first giving birth might decrease the risk of hip fractures in elderly Korean women.

• Nutrition Research and Practice
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• 제11권6호
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• pp.492-499
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• 2017

BACKGROUND/OBJECTIVES: This study aimed to investigate the association of dietary patterns with overweight risk and all-cause mortality in pediatric cancer patients. SUBJECTS/METHODS: Prospective cohort study was undertaken; 83 cancer patients admitted to the pediatric cancer ward at a university hospital in Seoul were included and followed for obesity and death over 24 months. Food consumption data were collected from patients using validated meal order sheets for breakfast, lunch, and dinner at the pediatric cancer ward over 3 days. Using principal component analysis, three dietary patterns were derived from 29 food groups. RESULTS: Eighteen deaths occurred among the patient cohort during the follow-up period. The "spicy & fried meat and fish" dietary pattern was positively associated with overweight risk at both baseline [odds ratio (OR) = 4.396, 95% confidence interval (CI) = 1.111-17.385, P for trend = 0.023] and after 6 months (OR = 4.088, 95% CI = 1.122-14.896, P for trend = 0.025) as well as all-cause mortality (hazard ratios = 5.124, 95% CI = 1.080-24.320, P for trend = 0.042), when comparing the highest and lowest tertiles after adjusting for covariates. The "fish, egg, meat, and fruits & vegetables" dietary pattern was associated with lower overweight risk after 24 months (OR = 0.157, 95% CI = 0.046-0.982, P for trend = 0.084). CONCLUSION: The results imply that dietary patterns might be associated with weight gain and premature death among pediatric cancer patients.

• Journal of Korean Medical Science
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• 제33권48호
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• pp.312.1-312.10
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• 2018

Background: Obesity is related to several comorbidities and mortality, but its relationship with acute kidney injury (AKI) and long-term mortality remain undetermined in patients undergoing coronary artery bypass grafting. Methods: Data from 3,018 patients (age ${\geq}18$ years) who underwent coronary artery bypass graft surgery from two tertiary referral centers were retrospectively reviewed between 2004 and 2015. Obesity was defined using the body mass index, according to the World Health Organization's recommendation. The odds and hazard ratios in post-surgical, AKI, and all-cause mortality were calculated after adjustment for multiple covariates. Patients were followed for $90{\pm}40.9$ months (maximum: 13 years). Results: Among the cohort, 37.4%, 2.4%, 21.1%, 35.1%, and 4.0% of patients were classified as normal weight, underweight, overweight-at-risk, obese I, and obese II, respectively. Post-surgical AKI developed in 799 patients (26.5%). Patients in the obese groups (overweight-at-risk to obese II) had a higher risk of AKI than did those in the normal-weight group. During the follow-up period, 787 patients (26.1%) died. Underweight patients had a higher risk of mortality than did normal-weight patients, whereas overweight-at-risk, obese I, and obese II patients showed better survival rates. Conclusion: After coronary artery bypass graft surgery, obese patients encountered a high risk of AKI, and underweight patients exhibited a low chance of survival. Awareness of both obese and underweight statuses should be raised in these patients.

• Gut and Liver
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• 제12권6호
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• pp.633-640
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• 2018

Background/Aims: Obesity is a risk factor for gastroesophageal reflux disease (GERD), with several studies demonstrating positive associations between body mass index (BMI) and GERD symptoms. However, little is known about the effect of BMI changes on erosive esophagitis (EE). In this study, we investigated whether BMI reduction could resolve EE. Methods: A retrospective cohort study was performed to assess the natural course of EE according to changes in BMI. Participants undergoing health check-ups from 2006 to 2012 were enrolled, and 1,126 subjects with EE were included. The degree of esophagitis was measured by upper endoscopy and serially checked over a 5-year follow-up. Logistic regression and Cox proportional hazards models were used to investigate the association between BMI reduction and EE resolution. Results: Substantial weight loss is associated with EE resolution. The adjusted odds ratio for EE resolution was 1.44 (95% confidence interval [CI], 1.09 to 1.92) among participants with a decrease in BMI compared to those with no decrease in BMI. The EE resolution rate was related to the degree of BMI reduction. The effect of weight loss on EE resolution was higher among subjects who lost more weight. Compared with subjects with no decrease in BMI, the hazard ratios for EE resolution were 1.09 (95% CI, 0.89 to 1.35), 1.31 (95% CI, 1.01 to 1.72) and 2.12 (95% CI, 1.44 to 3.12) in subjects with BMI reductions of ${\leq}1$, 1-2, and >$2kg/m^2$, respectively. Conclusions: EE resolution is associated with a decrease in BMI, and weight loss is potentially an effective GERD treatment.

• 당뇨병
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• 제19권3호
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• pp.135-139
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• 2018

The sodium-glucose cotransporter-2 inhibitor (SGLT2i) is a new anti-hyperglycemic agent that have function to concomitantly inhibit the reabsorption of glucose and sodium in the renal proximal convoluting tubule. Recent two cardiovascular outcome trials showed that a lower risk of cardiovascular events with SGLT2i in people with type 2 diabetes. In addition, prior real-world data demonstrated similar SGLT2i effects, but these studies were limited to the United States and Europe. Thus, the CVD-REAL (Comparative Effectiveness of Cardiovascular Outcomes in New Users of Sodium-Glucose Cotransporter-2 Inhibitors) 2 Study was investigated cardiovascular outcomes in those initiated on SGLT2i versus other glucose-lowering drugs (oGLDs) across 6 countries in the Asia Pacific, the Middle East, and North American regions. In Korea, 336,644 episodes of initiation in SGLT2i or oGLD group between September 2014 and December 2016 were identified in Korea National Health Insurance database after propensity score matching. SGLT2i users was associated with a lower risk of all-cause death (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.67~0.77), hospitalization for heart failure (HHF) (HR, 0.87; 95% CI, 0.82~0.92), all-cause death or HHF (HR, 0.81; 95% CI, 0.78~0.85), myocardial infarction (HR, 0.81; 95% CI, 0.74~0.89), and stroke (HR, 0.82; 95% CI, 0.78~0.86) compared with oGLD users. In conclusion, initiation of SGLT2i had a lower risk of cardiovascular events in people with type 2 diabetes compared with oGLDs.

• Earthquakes and Structures
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• 제17권5호
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• pp.511-519
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• 2019

The concrete gravity dam is one of the most important parts of the nation's infrastructure. Besides the benefits, the dam also has some potentially catastrophic disasters related to the life of citizens directly. During the lifetime of service, some degradations in a dam may occur as consequences of operating conditions, environmental aspects and deterioration in materials from natural causes, especially from dynamic loads. Cumulative Absolute Velocity (CAV) plays a key role to assess the operational condition of a structure under seismic hazard. In previous researches, CAV is normally used in Nuclear Power Plant (NPP) fields, but there are no particular criteria or studies that have been made on dam structure. This paper presents a method to calculate the limitation of CAV for the Bohyeonsan Dam in Korea, where the critical Peak Ground Acceleration (PGA) is estimated from twelve sets of selected earthquakes based on High Confidence of Low Probability of Failure (HCLPF). HCLPF point denotes 5% damage probability with 95% confidence level in the fragility curve, and the corresponding PGA expresses the crucial acceleration of this dam. For determining the status of the dam, a 2D finite element model is simulated by ABAQUS. At first, the dam's parameters are optimized by the Minitab tool using the method of Central Composite Design (CCD) for increasing model reliability. Then the Response Surface Methodology (RSM) is used for updating the model and the optimization is implemented from the selected model parameters. Finally, the recorded response of the concrete gravity dam is compared against the results obtained from solving the numerical model for identifying the physical condition of the structure.

• Imaging Science in Dentistry
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• 제51권3호
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• pp.223-235
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• 2021

Purpose: This study aimed to summarize the impact of neck and head radiation treatment on maxillofacial structures detected on panoramic radiographs. Materials and Methods: In this systematic review, the authors searched PubMed Central, Embase, Scopus, Cochrane Central Register of Controlled Trials, Web of Science, and Google Scholar for original research studies up to February 2020 that included the following Medical Subject Headings keywords: words related to "radiotherapy" and synonyms combined with keywords related to "panoramic radiography" and "oral diagnosis" and synonyms. Only original studies in English that investigated the maxillofacial effects of radiotherapy via panoramic radiographs were included. The quality of the selected manuscripts was evaluated by assessing the risk of bias using Cochrane's ROBINS-I tool for non-randomized studies. Results: Thirty-three studies were eligible and included in this review. The main objectives pertained to the assessment of the effects of radiation on maxillofacial structures, including bone architecture alterations, periodontal space widening, teeth development abnormalities, osteoradionecrosis, and implant bone loss. The number of participants evaluated ranged from 8 to 176. Conclusion: The interaction between ionizing radiation and maxillofacial structures results in hazard to the tissues involved, particularly the bone tissue, periosteum, connective tissue of the mucosa, and endothelium. Hard tissue changes due to radiation therapy can be detected on panoramic radiographs.