• Explosives and Blasting
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• v.22 no.3
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• pp.57-64
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• 2004

There are two major types of underwater blasting at Korea, bridges and harbor construction work. Pier blasting for lay the foundation bridges construction is used dry excavation working (drilling and charging) after pump out water and then fire pump in water that is same as bench blasting. In contrast, underwater blasting for harbor construction and increase of harbor load depth is used to barge with digging equipment that is in oder to drilling on the surface and blasting work(charge, hook-up) under water. Thus, there are need to special concern such as charge method and hook-up method different from tunnel blasting work and bench blasting work. If do not use special concern breaks out dead pressure and mis fire because of there are so many difficult condition such as water pressure, obstruct field of vision. In this study underwater blasting at Busan Harbor Construction have consider with special concern that is plastic pipe charge method used to MegaMITE I and specialized buoy hook- up method make far initial system detonate on the surface used to TLD. The results is designed blast pattern charge per delay effect an inspection of verify between predict velocity and measure velocity. minimized break out mis fire consideration charge method, hook up method. According to result best underwater blasting design is 105mm drilling dia, MeGAMITE II, HiNLL Plus(non electric detonator).

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.255-263
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• 1998

Dust-free garment prevents contamination which otherwise is caused by skin and clothes to protect from dust or dirt. Therefore, it requires high performance and should function as a working clothes. Clothes are a medium between human and thermal environmental system, and it is required to study human enviroment to ensure comfortableness of clothes and to satisfactorily go along with enviroment .This study investigates the physical and physiological features of dust-free garment used in the clean room at a semiconductor factory in oredr to scientifically clarify what the dust-free garmint is as well as to contribute to the design and development of high performance material and clothes. Three kinds of dust-free fabrics (DFG-I, DFG-II, DFG-III) which are being developed by a local company are used to manufacture dust-free garment. These dust-free garments are dressed and tested in such an enviroment as similar to semiconmemts with temperature at 23${\pm}$1$^{\circ}C$ and humidity at 50${\pm}$5%RH in order to investigate the thermo physiological and psychological features of human body. The results of this study are as follows. The results of this study are as follows. 1.The mean skin temperature was significantly different among the clothes, subjects and experimental time. Temperature tends to rise from the time of exercising load. Continuous motion coupled sealed clothes prevents heat transmittance, and temperature rises in the order of DFG-l, DFG-ll and DFG-lll as time course. 2.As for the skin temperature by local timperature is minimun on the head and torso and increares remarkably at the terminal part of human body. 3. As for the body mass loss was significantly higher in DFG-lll than DFG-l and DFG-ll. 4. Though there is no significant difference in the temperature within clothes among the kind of clothes temperature is 1$^{\circ}C$ higher in the back. Temperature within all the dust-free garments 29.7$^{\circ}C$ in the back and 31.3$^{\circ}C$ in the chest which belong to the comfort zone(31-33$^{\circ}C$). The relative humidity is 39.7%RH in the chest and 33.8%RH in the back which is slightly below the comfort zone(40-60%RH) 5. The thermal sensation belong to the comfort zone regardless of the kinds of clothes. The subjects feels a slight fatigue as times goes. As for the subjective sense of subjects the mean skin temperature as well as temperature and humidity within clothes show similar tendency. This means that they relate with each other.

• Journal of dental hygiene science
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• v.15 no.3
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• pp.280-286
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• 2015

The purpose of this study was to examine dental hygienist's emotional labor, burnout and turnover intention. Data were collected from 215 dental hygienists working at hospitals and dental clinics through self-administered questionnaire, and analyzed by statistical analysis using t-test, ANOVA, Pearson's correlation coefficient and multiple regression analysis. The main findings of the study are as follows: the higher the educational level of dental hygienists, and the bigger the size of dental institutions they work, and the lower the monthly income of dental hygienists, the higher the level of emotional labor of dental hygienists. Burnout was influenced on emotional labor and turnover intention. Emotion labor and turnover intention were influenced on burnout. Tenure under 5 years, five-day workweek (non), emotional burnout were found to have significant effects on the turnover intention. Dental hygienists were doing relatively high emotional labor, and it influences his burnout experience and turnover intention. It is needed to make the workplace better environment which can secure appropriate work load and rewards, and education programs etc.

• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.136-143
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• 2009

The injuries as a result of fall accidents is the one of the most common kind of injuries in Korea, especially fall from height is the top most common kind for fatal injuries. Futhermore, the number of fall injuries in manufacturing industry has been steadily increasing from 2000 to 2007. In 2007 the number of fall fatal injuries increased 10.6 % in comparison with the number in 2006. These numbers are 6~17 times higher than those for foreign countries such as the U.K and the USA. So, it is needed to make a study to reduce these numbers for manufacturing industry. To get the goals, we did research as followings. First, this study analyzed statistics by industry, by fall height, by common agent and so on to gain an insight into real aspect of fall injuries. It showed that ladder is the commonly cited agent for manufacturing industry, and 3 risky activities ; the ladder work, the load/unload work, and the maintenance work. Secondly, this study made a survey of manufacturing workers for their understandings of the most 3 risky activities. It showed that 'tendency to work easily' and 'difficulty of applying measures due to inherent working conditions' are main reasons for workers not to implement the preventive measures against the fall accidents. Thirdly, this study tested the slip characteristics of ladder base and lungs. The tests were done based on ANSI standard and KS. In addition to the standard condition, this study performed slip tests in wet and sandy conditions and compared the results with the those of standard condition. It showed that friction coefficient is standard condition > wet condition > sandy condition, and the friction coefficient of ladder for sandy condition is measured to be reduced by 63.9% compared with that for standard condition. Finally, this study developed safety work models for using of portable ladders in consideration of the safety standards of foreign countries such as the U.K, the USA, and the Australia.

• Journal of dental hygiene science
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• v.11 no.6
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• pp.553-562
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• 2011

This study was purposed to evaluate the level of occupational stress and the work-related factors of occupational stress in dental hygienists. The study was conducted during the period from May to October 2010 with study population consisted of 316 dental hygienists. The occupational stress was estimated with questionnaire of the Korean Occupational Stress Scale(KOSS) and the work-related factors were consisted with 9 work characteristics. Data analysis was performed with t-test, ANOVA and multiple regression analysis using SPSS(win ver 18.0) program. The level of occupational stress was $52.42{\pm}4.95$ in dental hygienists. The levels of sub-scales for occupational stress were $64.56{\pm}12.17$ in interpersonal conflict, $59.85{\pm}13.59$ in physical environment, $54.60{\pm}13.51$ in organizational system, $52.37{\pm}11.47$ in job demand, $51.71{\pm}10.58$ in lack of reward, $48.14{\pm}12.97$ in insufficient job control, $46.68{\pm}9.25$ in job insecurity, $41.46{\pm}15.98$ in occupational climate, respectively. According to multiple regression analysis, physical burden and daily repetitive working hour were work-related factors of occupational stress in dental hygienists. To conclude, the occupational stress in dental hygienists was higher than mean score of reference values of occupational stress in Korean workers and methods for reducing work load and work hours considering work characteristics of dental hygienist are needed to prevent occupational stress in dental hygienists.

• Korean Journal of Community Nutrition
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• v.4 no.1
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• pp.83-94
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• 1999

This study was carried out to investigate the general characteristics of public health nutritionists, the current status of nutrition services operation, the recognition about nutrition services of public health center related man power, the job satisfaction and self-assessment and the need for a retraining course of public health nutritionists. The subjects were 58 public health nutritionists who responded to the questionnaire distributed at the annual retraining program in 1998. The results of this study are summarized as follows. 1) 46.5% of the nutritionists were 26-30 years old, 62.1% were 4 year university graduates 74.1% were food and nutrition majors and 51.7% were daily workers. 2) Among the public health center-related manpower, the recognition about nutrition services was the highest for the manager of family health section, followed by the head of public health centers, and then the general nurse in public health centers. 3) The ranking of the reasons for job satisfaction of the public health nutritionists was, relationship with colleagues(3.84), inhabitants response after nutrition counselling(3.53), specialized value realization/conviction about duty(3.35), contents of the work(3.10), value achievement(3.08), self achievement/development(3.00), self discretion(2.92), participation in policy decisions(2.90), work load(2.75), chance of retraining and acquisition of new information(2.73), working environment(2.69), supervisio $n^port by superiors(2.67), salary(2.38), supply of necessary education material, technique(2.37), and budget security(2.22). 4) The satisfaction of the inhabitant's responses after nutrition counseling was the highest among the 4 year university graduates(p<0.05), the satisfaction of the specialized value realization/conviction about duty was the highest among the nutritionists 26-30 years old(p<0.05). Food and nutrition majors(p<0.05) and those having worked less than 3-5years at public health centers also showed much satisfaction(p<0.05). Satisfaction with the salary was the lowest among the food and nutrition majors(p<0.01) and daily workers(p<0.001). The satisfaction with the participation in policy decisions was the lowest among the daily workers(p<0.01). 5) The ranking for the level of self-assessment were, nutrition and dietetic practice(2.92), communication(2.80), management(2.77), public health science and practice(2.66)(p<0.01). The general characteristics such as the level of education, major, employment condition, current public health center's tenure, and charge experience of the nutrition guidance work were not significantly related to self-assessment except the management part(p<0.05). The higher the satisfaction of specialized value realization/conviction about the duty, the better the total score on the self-assessment(p<0.05)..

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.175-181
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• 2004

This study is about a section where underground water level occurs at the underground 5m depth by the excavation of the ground, as a stream is adjacent to a excavation section of High Speed Railway ${\bigcirc}{\bigcirc}$ Station construction sections and a reservoir being always full of water is located at the left side of the construction section. Therefore this test is executed for the design and construction of buoyance anchors able to permanently prevent buoyance by the underground water level at working and for the stable construction and permanent smooth maintenance of structures. In this test, bar type anchors are divided according to their length and standard to execute test-anchor test, and In spot test, 9 test-anchors test, proof test to construction process, suitability test and acceptance test are executed 4 times to 9 test-anchors by dividing anchors according to the length of permanent anchor, the outer diameter of bar and boring diameter. Standard motion characteristic centering on load transmission and break mechanism of bar-type anchors for the prevention of buoyance will be showed in the thesis.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.249-257
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• 2018

The number of deaths for railway traffic accidents is mainly caused by working close to the track, or when unauthorized passage pass through the track. The safety fences are being used to ensure safety for workers close to the track, and to improve the efficiency of the work, without interfering with the passage of trains. However, a safety fence for railway tracks needs to be examined to see if it will interfere with the passage of trains. The purpose of this study is to analyze the safe distance between train and safety fence developed in Korea. In addition, the lateral load condition of wind pressure by trains is estimated and numerical analysis is carried out according to the installation intervals of railway safety fences. It has been confirmed that the proper spacing between the train and the railway safety fence should be at least 200 mm from the vehicle limit, and that the proper spacing of railway safety fence must be calculated in consideration of the wind pressure by trains.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.796-805
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• 2020

Purpose: A static loading test was performed to evaluate the ultimate flexural strength of a girder in which 80MPa high-strength concrete was synthesized on the compressive flange of the I-shape steel girder. Method: This test is designed and fabricated two types of specimens with different shear-connection specifications, and evaluated their ultimate flexural behavior until reaching the extreme event limit states. In addition, the ultimate strength was evaluated by comparing the test results and the results of the strain compatibility method. Result: By confirming the displacement within 0.02mm as a result of the relative slip measurement, it was verified that the two specimens secured perfect bonding. Therefore, the difference in the shear specification does not have a great effect on the stiffness, and if the specimens are completely synthesized, there is no difference in the behavior until it reaches the extreme-event limit states. Conclusion: The girder to be tested has a working load within the elastic range and meets the usability requirements for allowable deflection. Therefore, even if a part of the casing is subjected to the tensile force at the level of cracking, the deck will first reach the compression failure due to the role of the reinforcing bar.

• Journal of the Korean GEO-environmental Society
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• v.20 no.11
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• pp.11-22
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• 2019

Limit state design (LSD) and allowable stress design (ASD) are two main types of soil nailing design methodologies. In the LSD method, stability is determined by applying individual coefficients to ground strength, working load and etc. The ASD method calculates the safety factor and compares it with the minimum safety factor to determine the stability. The global design trend of soil nailing system is changing from the ASD method to the LSD method. The design method in Korea still adopts the ASD philosophy while others mostly do the limit state design. In this study, four soil nail design methods, 'FHWA GEC 7' in U.S. (2015), 'Clouterre' in France (1991), 'Soil nailing - best practice guidance' in U.K. (2005), 'Geoguide 7' in Hongkong (2008), and 'Design guide for slope in construction work' in Korea (2016) were applied to the evaluation of the stability and the results were analyzed comparatively in brief. It is revealed that the design method of 'the overall stability of soil nail walls' in Korea is the most conservative and next those by FHWA, Clouterre and CIRIA become more conservative in order. However, the difference of results obtained from FHWA and Clouterre is negligible. Also, this study found out that efforts to improve domestic design criterion are needed.