• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.510-519
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• 2019

The aim of this study was to set a defect classification framework and evaluate the defect risks in apartment buildings For this, approximately 15,056 defect items for 133 apartment buildings were examined. As a result of the analysis, the major defect of the RC work was cracks, which were found mainly in public locations. Moreover, the RC work was found to exhibit a high defect risk of water problem and surface appearance, which are highly connected with cracks. Second, the finish work has a high defect risk because it is composed of various work types, and there are many kinds of materials and construction parts involved. Third, the major defects of the waterproof work were incorrect installation and missing tasks, which have high defect risks in the garage. This is because defects that require rework occur mainly in the underground garage. Based on these results, this study proposed countermeasures for defect risk management to be considered in the construction, handover, post-handover, and occupancy phases. These have been set in detail based on the three zones: low frequency high severity (LFHS), low frequency low severity (LFLS), and high frequency low severity (HFLS).

• Fire Science and Engineering
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• v.33 no.4
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• pp.16-27
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• 2019

A burning test was conducted on the smoke and combustion gases generated from cypress wood treated with sodium silicate, 3-aminopropyltrimethoxysilane sol, 3-(2-aminoethylamino)propylmethyldimethoxysilane sol, and 3-(2-aminoethylamino) propyltrimethoxysilane sol. The silicone compound sol was applied to each of the cypress wood specimens three times with a brush. The smoke and combustion generation gas were analyzed using a cone calorimeter (ISO 5660-1) and the smoke was also evaluated by applying new smoke risk assessment method. The smoke performance index (SPI) of the cypress treated with silicone compound increased 1.66 to 8.42 times and the smoke growth index (SGI) was 11.8 to 88.2%, respectively. The smoke intensity (SI) is expected to be 1.0~50.5% lower than that of the base specimens, resulting in lower smoke and fire hazards. The third maximum carbon monoxide (CO_peak) concentration of the specimens treated with silicone compounds was 22.5~33.3% lower than that of the base specimens. On the other hand, it produced potentially fatal toxicity that was 1.48~1.72 times higher than the US Occupational Safety and Health Administration (OSHA) acceptance standard (PEL). Cypress wood itself produced a high carbon monoxide concentration, but the silicon compound played a role in reducing this level.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.103-116
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• 2017

We studied the actual condition of work environment and work morale according to the type of employment of service workers by using the raw data of the Fourth Work Environment Survey (2014) conducted by the Institute of Occupational Safety and Health. In this study, the condition of work environment were composed of work posture, emotional labor, and work autonomy. Also, dimensions related to work morale were composed of competence, job satisfaction, social support, and job stress. In addition, the employment was classified into three types of regular workers, temporary workers, and daily workers. The results showed that temporary and daily workers were more likely to work in a less favorable environment than regular workers, and there was a close correlation between work environment and work morale. Based on this study, it is possible to know about the actual situation and problems of the service workers, and it is hoped that company can search for measures to increase the working environment and work morale of the workers in order to provide better service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3260-3269
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• 2014

The construction industry has strong ties with other industries, and so construction company insolvency also has a strong influence on other industries. Prediction models addressing the insolvency of construction company have been well studied. Although factors contributing to insolvency must precede those of predictions of insolvency, studies on these contributing factors are limited. The purpose of this study is to analyze the influence of changes in the housing market on construction company insolvency by using the Vector Error Correction Model. Construction companies were divided into two groups, and the expected default frequency(EDF), which indicates insolvency of each company was measured through the KMV model. The results verified that 10 largest construction companies were in a better financial condition compared to relatively smaller construction companies. As a result of conducting impulse response analysis, the EDF of large companies was found to be more sensitive to housing market change than that of small- and medium-sized construction companies.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.670-676
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• 2018

Experiments on combustion gases generation of untreated cypress specimens or treated with boric acid, ammonium pentaborate, and boric acid/ammonium pentaborate additive were carried out. Test specimens were painted three times with 15 wt% boron compound aqueous solutions. After drying, the generation of combustion gas was analyzed using a cone calorimeter (ISO 5660-1). As a result, comparing to untreated specimen, the smoke performance index (SPI) of the specimens treated with the boron compound increased by 1.37 to 2.68 times and the smoke growth index (SGI) decreased by 29.4 to 52.9%. The smoke intensity (SI) of the specimens treated with boron compounds is expected to be 1.16 to 3.92 times lower than that of untreated specimens, resulting in lower smoke and fire hazards. Also, the maximum carbon monoxide ($CO_{peak}$) concentration of specimens treated with boron compounds was 12.7 to 30.9% lower than that of untreated specimens. However, it was measured to produce fatal toxicities from 1.52 to 1.92 times higher than that of permissible exposure limits (PEL) by Occupational Safety and Health Administration (OSHA). The boron compounds played a role in reducing carbon monoxide, but it did not meet the expectation of reduction effect because of the high concentration of carbon monoxide in cypress itself.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.5
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• pp.449-460
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• 2015

Carbonaceous aerosol is generally classified into OC (organic carbon) and EC (elemental carbon) by thermal optical analysis. Both NIOSH (National institute of occupational safety and health) with high temperature (HighT) and IMPROVE-A (Interagency monitoring of protected visual environments) with low temperature (LowT) protocols are widely used. In this study, both protocols were applied for ambient $PM_{2.5}$ samples (Daejeon, Korea) in order to underpin differences in OC and EC measurements. An excellent agreement between NIOSH and IMPROVE-A protocol was observed for TC (total carbon). However, significant differences between OC and EC appeared and the differences were larger for EC than OC. The main differences between two protocols are temperature profile and charring correction method. For the same charring correction method, HighT_OC was 10% higher than LowT_ OC, while HighT_EC was 15% and 33% lower than LowT_EC for TOT (thermal-optical transmittance) and TOR (thermal-optical reflectance), respectively. This difference may be caused by the temperature of OC4 in He step and possibly difference in POC (pryorilized OC) formation. For the same temperature profile, OC by TOT was about 26% higher than that by TOR. In contrast, EC by TOT was about 50% lower than that by TOR. POC was also dependent on both temperature profile and the charring correction method, showing much distinctive differences for the charring correction method (i.e., POC by TOT to POC by TOR ratio is about 2). This difference might be caused by different characteristics between transmittance and reflectance for monitoring POC formation within filters. Results from this study showed that OC and EC depends on applied analysis protocol as shown other studies. Because of the nature of the thermal optical analysis, it may not be possible to have an absolute standard analysis protocol that is applicable for any ambient $PM_{2.5}$. Nevertheless, in order to provide consistent measurement results for scientists and policy makers, future studies should focus on developing a harmonized standard analysis protocol that is suitable for a specific air domain and minimizes variations in OC and EC measurement results. In addition, future elaborate studies are required to find and understand the causes of the differences.

• Journal of Ginseng Research
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• v.43 no.2
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• pp.242-251
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• 2019

Background: Korean Red Ginseng has been widely used in traditional oriental medicine for a prolonged period, and its pharmacological effects have been extensively investigated. In addition, Angelica gigas and deer antlers were also used as a tonic medicine with Korean Red Ginseng as the oriental herbal therapy. Methods: This study was conducted to evaluate the potential toxicological effect of KGC-HJ3, Korean Red Ginseng with angelica gigas and deer antlers, on reproductive and developmental functions including fertility, early embryonic development, maternal function, and embryo-fetal development. KGC-HJ3 was administered by oral gavage to Sprague-Dawley rats (22 animals per sex per group) at dose levels of 0 mg/kg (control), 500 mg/kg, 1000 mg/kg, and 2000 mg/kg to evaluate the potential toxicological effect on fertility and early embryonic development. In addition, KGC-HJ3 was also administered by oral gavage to mating-proven Sprague-Dawley rats (22 females per group) during the major organogenesis period at dose levels of 0 mg/kg (control), 500 mg/kg, 1000 mg/kg, and 2000 mg/kg to evaluate the potential toxicological effect on maternal function and embryo-fetal development. Results and conclusion: No test item-related changes in parameters for fertility, early embryonic development, maternal function, and embryo-fetal development were observed during the study period. On the basis of these results, it was concluded that KGC-HJ3 did not have toxicological potential on developmental and reproductive functions. Therefore, no observed adverse effect levels of KGC-HJ3 for fertility, early embryonic development, maternal function, and embryo-fetal development is considered to be at least 2000 mg/kg/day.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.68-77
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• 2013

Derived Investigation levels(DILs) were calculated to protect the workers from the effects of both radiological hazard and chemical toxicity by uranium intake. Investigation Levels(ILs) of committed effective dose of 2 mSv $y^{-1}-6$ mSv $y^{-1}$ and uranium concentration of 0.3 ${\mu}g$ $g^{-1}$ in kidney, based on Korean Nuclaer Safety Act, Korean Occupational Safety and Health Act and current scientific studies of uranium intake were assumed. DILs of radiological hazard and chemical toxicity were then calculated based on the concentration of uranium in air of workplace, the lung monitoring and urine analysis, respectively. As a result, in case of the nuclear fuel fabrication plant where 3.5% enriched uranium is handled, derived investigation level(DIL) for the control of the concentration of uranium in the air of workplace assumed with 15-min acute inhalation was 0.6 mg $m^{-3}$ for all types of uranium. DILs for the control of the average concentration of uranium in air of workplace, assuming an 8-hour workday, were 15.21 ${\mu}g$ $m^{-3}$ of Type F uranium, 0.41-1.23 Bq $m^{-3}$ and 0.13-0.39 Bq $m^{-3}$ for Type M and Type S uranium, respectively. DILs for the lung monitoring assumed with a period of 6-month interval were 0.37-1.11 Bq and 0.39-1.17 Bq in acute and chronic inhalation for Type M, respectively and 0.30- 0.91 Bq and 0.19-0.57 Bq in acute and chronic inhalation for Type S, respectively. Since a detection limit of typical germanium detector for the measurement of 235U activity is 4 Bq, DILs calculated for the lung monitoring were not appropriate. DILs for urine analysis, for which an interval was assumed to be 1 month, were 14.57 ${\mu}g$ $L^{-1}$ based on chemical toxicity after acute inhalation. In addition, acute and chronic inhalation of Type M were calculated 2.85-8.58 ${\mu}g$ $L^{-1}$ and 1.09-3.27 ${\mu}g$ $L^{-1}$ based on the radiological hazard, respectively.

• Journal of the Ergonomics Society of Korea
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• v.36 no.3
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• pp.183-196
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• 2017

Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. Basically, the difference between univariate and multivariate analysis is that univariate analysis deals with one predictor variable at a time, whereas multivariate analysis deals with multiple predictor variables combined in a predetermined manner. The univariate analysis could show how each variable is associated with epicondyle pain. This may allow more appropriate weighting factors to be determined and therefore improve the performance of the EEM.