• Journal of Korean Society for Quality Management
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• v.12 no.1
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• pp.35-44
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• 1984

Spandex is a elastomeric fiber in which the-fiber-forming substance is a long chain polymer consisting of at least 85% segmented polyurethane. In the polyurethanes there are the additional oxygen atoms in the main chains of the molecule. The effect of these oxygen atoms is to make the molecule flexible. From a physical point of view, elasicity and recovery from stretch are the most important properties of polyurethane, so its use had now expanded into many knitting industry. In this paper, we wish to Test the effect of some finishing conditions on the quality of polyurethane.

• Proceedings of the Safety Management and Science Conference
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• 2008.11a
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• pp.303-316
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• 2008

For the past 25 years, Korean semiconductor has experienced enormous growth to be the highest production country in the world. Semiconductor industry is very time sensitive and driven by technology and process, and requires 24-hour full operation. The environment includes many different types of equipment, utilities, different gases and toxic chemicals as well as high voltage electricity. We have performed a survey with 3-shift engineers and workers in one line. The content of the questionnaire was about the correlation between fatigue and performance shaping factor (work type and work ability), and as a result we were able to deduce the correlation, p-value and the pattern of scatter plot. The shape of the model was made of 4 blocks for fatigue, 5 blocks for work type and 5 blocks for work ability, i. e. 14 blocks in total. As a conclusion to this findings, there was a correlation between fatigue and work type and work ability specifically in semiconductor industry, and we need some effort to reduce this.

• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.141-151
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• 2007

The current standards and specifications for the road pavement construction have been developed based on materials and construction methods. The pavements constructed in accordance with those specifications do not guarantee high performance of pavements since they do not consider long-term performance of pavements. Therefore, as part of the study to develop performance-based construction standards for pavements, the payment adjustment methods based on the pavement performance are currently being developed. This paper presents preliminary studies performed to develop the payment adjustment methods when there is deficiency in the concrete slab thickness that is one oi the most important factors for the pavement design and construction. First, the payment adjustment methods in USA were investigated. Then, the AASHTO failure equation, the relationship between slab thickness and stress, and the relationship between stress level and pavement life were employed to propose the payment adjustment concepts based on the pavement performance for the deficient slab thickness. The variation in the slab thickness according to measurement locations was investigated by taking cores. In addition, the measurement methods of slab thickness and the variation of measured thicknesses depending on performers were analyzed, and finally the methodology to develop the thickness deficiency ranges for the use in the payment adjustment methods was proposed.

• The Korean Journal of Food And Nutrition
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• v.26 no.3
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• pp.485-491
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• 2013

Rhodiola spp. and red ginseng have been used for food and medicinal applications in disease chemoprevention in many Asian countries. Increased oxidative stress by reactive oxygen species (ROS) has been proposed to be a major cause of muscle fatigue. The present study was designed to investigate the protective effects of a fermented hot-water extract mixture from Rhodiola sachalinensis and red ginseng (MFR) on cell damage and the antioxidant enzyme system in $H_2O_2$-induced oxidative stress in skeletal muscle cells. C2C12 myoblasts were treated with various concentrations of NFR (non-fermented Rhodiola sachalinensis extract), FR (fermented hot-water extract from Rhodiola sachalinensis) and MFR for up to 5 days after the standard induction of differentiation, followed by semi-quantitative RT-PCR. MFR treatment dose-dependently protected oxidative damage of C2C12 cells. The treatment with MFR also enhanced mRNA expressions of MyoD, Cu/Zn SOD, Mn-SOD and GPX up to 16%. These results indicate that MFR exerts an anti-oxidative effect through a mechanism (s) that may involve the up-regulation of antioxidant enzymes, which may be important for the cellular redox environment in muscle cells.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.733-740
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• 2017

'The facilities standards of water supply' issued by the Ministry of Environment in 2004 indicates that expansion joints cannot be used in welding water supply steel pipes. However, their reason is not clear and it is difficult to confirm the stability of the steel pipe for a water supply pipeline. The purpose of this study is to determine whether or not an expansion joint is necessary to improve the stability of water supply in steel pipe through a displacement analysis of the pipework. The test results are as follows. Firstly, it was found that expansion and contraction of the water supply steel pipe (D 2,400 mm) occur repeatedly in 4 cycles per year, and the maximum expansion and contraction amount of the pipe is 13.03 mm in 1.24 km pipelines. Secondly, the thermal stress caused by expansion and contraction of the steel pipe is $13.7{\sim}36.1kgf/cm^2$ according to the burial depth (0~4 m). The main comparison factors to determine the stability of the steel pipe (STWW 400) were the allowable tensile strength and the fatigue limit, which were computed to be $4,100kgf/cm^2$ and $1,840kgf/cm^2$, respectively. Finally, the thermal stress of the steel pipe is very small compared to the allowable tensile stress and fatigue stress. Therefore, thermal stress does not affect the stability of the steel pipe, although the expansion and contraction of the steel pipe occurs by temperature changes. In conclusion, the study demonstrated that expansion joints are not required in water supply steel pipelines.

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.405-414
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• 2006

The purpose of this study was to find out morbidity rate and pattern of occupational disease and affect of variables related disease of Fishing crew The subjects this study were 624 Fishing crew who took education course in Korea Institute of Maritime and Fisheries Technology. This questionnaire was focused on finding the basic data for prevention of occupational disease and promotion health on the Fishing crew The collected data were analyzed by using descriptive statistics, Chi-square, cross tab by SPSS package. The result of this study are as follow. 1)The morbidity rate within recent 12 months was 70.2%. there were significant differences of occurred disease in age, rank, perceived health status, fatigue symptoms, rest time, workload, overtime duration 2) the more aging(p<0.01), perceived fatigue(p<0.01), workload(p<0.01), overtime(p<0.05) and the less perceived health status(p<0.01), rest time(p<0.01), the higher morbidity rate 3) Considering disease unable to work more than 4 hour, the number of those who had musculoskeletal disease were 20.9%, which revealed the highest rate, digestive disease 14.3%, traumatic disease 13.5%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.29-38
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• 2006

The purpose of this study was to find out morbidity rate and pattern of occupational disease and affect of variables related disease of Fishing sailors' The subjects this study were 624 fisheries sailors' who took education course in Korea Institute of Maritime and Fisheries Technology. This questionnaire was focused on finding the basic data for prevention of occupational disease and promotion health on the fishing sailors' The collected data were analyzed by using descriptive statistics, Chi-square, cross tab by SPSS package. The result of this study are as follow. 1)The morbidity rate within recent 12 months was 70.2%. there were significant differences of occurred disease in age, rank, perceived health status, fatigue symptoms, rest time, workload, overtime duration 2) the more aging(p<0.01), perceived fatigue(p<0.01), workload(p<0.01), overtime(p<0.05) and the less perceived health status(p<0.01), rest time(p<0.01), the higher morbidity rate 3) Considering disease unable to work more tlnn 4 hour, the number of those who had musculoskeletal disease were 20.9%, which revealed the highest rate, digestive disease 14.3%, traumatic disease 13.5%.

• Clinical and Experimental Pediatrics
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• v.45 no.11
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• pp.1340-1345
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• 2002

Purpose : We studied the prevalence of snoring and its association with diseases, obesity and environmental factors, as well as sleep disturbance arising from snoring, in school-aged children. Methods : The survey was performed by a special questionnaire on 1,707 children at elementary schools from 1 to 30 July 2001 in Gwangju City. The prevalence of snoring, associated factors, and sleep disturbance were evaluated. Results : 266(16.5%) of the children snored at least once a week. 73(4.3%) of the children snored almost every day. Regarding the associated factors of snoring : There was a statistically significant difference between snoring and nonsnoring groups due to gender, obesity, sinusitis, tonsillar hypertrophy, bronchial asthma and allergic rhinitis. Of them, male gender, tonsillar hypertrophy, and obesity were significant risk factors for development of snoring. Especially, the odds ratio increased to 1.048(CI, 1.004-1.659), 1.748(CI, 1.175-2.599), and 2.266(CI, 1.300-3.950) in children with an obesity index of 20-29%, 30-49%, ${\geq}50%$, respectively. There was a statistically significant association of snoring with decreased sleep duration, sleep talking, and drowsiness during the day as a result of sleep disturbance. Conclusion : 16.5% of school-aged children snored at least once a week. The association of snoring with tonsillar hypertrophy, obesity and gender as risk factors was demonstrated in this study.

• Korean Journal of Psychosomatic Medicine
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• v.26 no.2
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• pp.77-85
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• 2018

Objectives : This study aimed to investigate the level of distress using the distress thermometer (DT) and the factors associated with distress in postoperative breast cancer (BC) patients. Methods : DT and WHOQOL-BREF (World Health Organization Quality of Life Scale Abbreviated Version) along with sociodemographic variables were assessed in patients undergoing surgery for their first treatment of BC within one week postoperatively. The distress group consisted of participants with a DT score ${\geq}4$. The prevalence and associative factors of distress were examined by descriptive, univariable, and logistic regression analysis. Results : Three hundred seven women were recruited, and 264 subjects were finally analyzed. A total of 173 (65.5%) were classified into the distress group. The distress group showed significantly younger age (p=0.045), living without a spouse (p=0.032), and worse quality of life (QOL) as measured by overall QOL (p=0.009), general health (p=0.005), physical health domain (p<0.000), and psychological health domain (p=0.002). The logistic regression analysis showed that patients aged 40-49 years were more likely to experience distress than those aged ${\geq}60years$ (Odds ratios [OR]=2.992, 95% confidence interval [CI] 1.241-7.215). Moreover, the WHOQOL-BREF physical health domain was a predictive factor of distress (OR=0.777, 95% CI 0.692-0.873). Conclusions : A substantial proportion of patients are experiencing significant distress after BC surgery. It would be expected that distress management, especially in the middle-aged patients and in the domain of physical QOL (e.g., pain, insomnia, fatigue), from the early BC treatment stage might reduce chronic distress.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.4
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• pp.277-282
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• 2014

Recently, much attention has been paid to nonlinear ultrasonic technology as a potential tool to assess hidden damages that cannot be detected by conventional ultrasonic testing. One nonlinear ultrasonic technique is measurement of the resonance frequency shift, which is based on the hysteresis of the material elasticity. Sophisticated measurement of resonance frequency is required, because the change in resonance frequency is usually quite small. In this investigation, the nonlinear electromagnetic acoustic resonance (NEMAR) method was employed. The NEMAR method uses noncontact electromagnetic acoustic transducers (EMATs) in order to minimize the effect of the transducer on the frequency response of the object. Aluminum plate specimens that underwent three point bending fatigue were tested with a shear wave EMAT. The hysteretic nonlinear parameter ${\alpha}$, a key indicator of damage, was calculated from the resonance frequency shift at several levels of input voltage. The hysteretic nonlinear parameter of a damaged sample was compared to that of an intact one, showing a difference in the values.