• Biomedical Science Letters
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• v.11 no.2
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• pp.143-152
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• 2005

To investigate the exposure effect of polycyclic aromatic hydrocarbons (PAHs), we analyzed the relationship between urinary 8-hydroxydeoxyguanosine (8-OHdG) concentration and PAHs exposure. The study population contained 44 workers in steel-pipe coating and paint manufacture industries. We measured airborne total PAHs as an external dose, urinary 1-hydroxypyrene (1-OHP) as an internal dose of PAHs exposure, and urinary 8-OHdG as an effective dose of oxidative DNA damage. There was significant correlation between the urinary concentration of l-OHP and the environmental concentration of PAHs, pyrene, urinary cotinine, AST, and GGT. The mean of urinary 8-OHdG was $17.07\pm1.706{\mu}g/g$ creatinine in workers exposed to airborne PAHs. There was significant correlation between the urinary concentration of 8-0HdG and the airborne concentration of PAHs. From the results of stepwise multiple regression analysis about 8-OHdG, significant independents was total PAHs. In this study, there were significant correlation between the urinary concentration of 8-OHdG and the airborne concentration of PAHs. The urinary 1-OHP was effective index as a biomarker of airborne PAHs in workplace. But it was influenced by non-occupational PAHs source, smoking and biomarkers of liver function test.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.41-48
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• 2012

In this study the negative skin friction test of foundation pile was performed in order to monitor the negative skin frictional force acting on the steel pipe pile installed in soft soil. The monitored frictional stresses obtained from the long-term loading test. Through the long-term frictional stress monitoring test, the economical period for the construction of the superstructure was determined. The following conclusion were derived from this study: (1) In soft soil, negative skin friction increases with the increase in the rate of settlement. (2) In the friction relationship graph, the period where there is no frictional strain increase is verified and the time for the construction of the superstructure is determined. (3) The pile loading test was performed and the negative skin friction was compared with the test results. It was determined that the negative skin friction after driving was larger than the negative skin friction obtained from the loading test. 15 days after the construction, the monitored value was similar with the theoretical data. (4) It was determined that even during the occurrence of negative skin friction an economical construction management can be performed using the long-term monitoring method of negative skin friction.

• Tribology and Lubricants
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• v.30 no.2
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• pp.124-129
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• 2014

The piping system accounts for a large portion of the machinery structure of a plant, and is considered as a very important mechanical structure for plant safety. Accordingly, it is used in most energy plants in the nuclear, gas, and heavy chemical industries. In particular, the piping system for a nuclear plant is generally complicated and uses the reactor and its cooling system. The piping equipment is exposed to diverse loads such as weight, temperature, pressure, and seismic load from pipes and fluids, and is used to transfer steam, oil, and gas. In ultrasound infrared thermography, which is an active thermography technology, a 15-100 kHz ultrasound wave is applied to the subject, and the resulting heat from the defective parts is measured using a thermography camera. Because this technique can inspect a large area simultaneously and detect defects such as cracks and delamination in real time, it is used to detect defects in the new and renewable energy, car, and aerospace industries, and recently, in piping defect detection. In this study, ultrasound infrared thermography is used to detect information for the diagnosis of nuclear equipment and structures. Test specimens are prepared with piping materials for nuclear plants, and the optimally designed ultrasound horn and ultrasound vibration system is used to determine damages on nuclear plant piping and detect defects. Additionally, the detected images are used to improve the reliability of the surface and internal defect detection for nuclear piping materials, and their field applicability and reliability is verified.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.212-223
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• 2015

Purpose: Physical properties of Detarium microcarpum seeds were investigated as a function of moisture content to explore the possibility of developing bulk handling and processing equipment. Methods: Seed size, surface area, and 1,000-seed weight were determined by measuring the three principal axes, measuring area on a graph paper, and counting and weighing seeds. Particle and bulk densities were determined using liquid displacement and weight in a measuring cylinder, respectively. Porosity was computed from particle and bulk densities. Roundness and sphericity were measured using shadowgraphs. Angle of repose and static and kinetic coefficients of friction were determined using the vertical cylindrical pipe method, an inclined plane, and a kinetic coefficient of friction apparatus. Results: In the moisture range of 8.2%-28.5% (db), the major, intermediate, and the minor axes increased from 2.95 to 3.21 cm, 1.85 to 2.61 cm, and 0.40 to 1.21 cm, respectively. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose increased from 354.62 to $433.19cm^2$, 3.184 to 3.737 kg, 1060 to $1316kg/m^3$, and 30.0% to 53.1%, respectively, whereas bulk density decreased from 647.6 to $617.2kg/m^3$. Angle of repose increased from $13.9^{\circ}$ to $28.4^{\circ}$. Static and kinetic coefficients of friction varied between 0.096 and 0.638 on different structural surfaces. Conclusions: Arithmetic mean, geometric mean, and equivalent sphere effective diameters determined at the same moisture level were significantly different from each other, with the arithmetic mean diameter being greatest. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose all increased linearly with moisture content. Bulk density decreased linearly with moisture content. The coefficients of friction had linear relationships with moisture content. The highest values of static and kinetic coefficients of friction were observed on galvanized steel and hessian fabric, respectively, whereas the lowest values were observed on fiberglass.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.5-21
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• 2012

In our country, in the case of traditional design of pile foundations, only a design depending on end bearing has been performed. However, through the load transfer measurement data that have been carried out for in-situ piles, it was known that skin frictional force was mobilized greatly. In this study, through the analysis of the load transfer test cases of driven steel pipe piles and large-diameter drilled shafts, load bearing aspects of pile foundation depending on pile construction methods and pile load test methods were established. The average sharing ratios of skin frictional force were independent of pile types, pile load test methods, relative pile lengths, pile diameters and soil types. Because the average sharing ratios were over 50%, the case pile foundations mostly behaved as a friction pile and the extremely partial case pile foundation behaved as a combined load bearing pile.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.95-100
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• 2004

H-pile can be more easily driven than pipe pile by pile driver and shows high skin friction and plugging effect. And lately It is well grown that the high strength H-pile has been widely used f3r pile foundations. To compare the skin frictions of H piles under different density soil conditions, this paper presents results of a series of model tests on vertically loaded group piles. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements $(2\times2,\;3\tunes3)$, pile space(2D, 4D, 6D), and soil density$(D_r=40\%,\;80\%)$ were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that compression load for group piles increases as number of piles increase and piles space ratic decrease to $D_r=40\%$ of soil density. The analysis also found that the theoretical value of skin friction for group piles is greater than practical value as piles space ratio increases to $D_r=40\%$ of soil density. Piles showed the greatest difference of the skin friction in case that the pile space ratio(S/D) is 6. The theoretical value by Meyerhof and DM-7 showed 1.83 times and 1.32 times respectively as great as practical value in case of S/D=6 and $2\times2$.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.4
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• pp.15-25
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• 2018

The accident risk at the construction workplace associated with agricultural engineering is comparatively higher than those of other fields due mainly to its complex work types and processes. Agricultural engineering deals with a variety of agricultural infrastructures from irrigation and drainage facilities to giant-scale coastal reclamation land infrastructures. The characteristics that most agricultural projects have conducted on a small-scale even worsen the situation drawing low attentions to risk management. Therefore, systematical risk assessment that focuses on details of agricultural construction work process is required in order to enhance safety management capacity and to prevent repetitive accidents ultimately. This study aims to categorize construction work types and processes of agricultural construction works, and to quantitatively assess the accident risk of them based on accident analysis. Regarding classification of construction works, actual 827 accident cases were thoroughly reviewed and coded by their construction site, facility and work type, project scale and so on. Most accidents (71.8 % of total cases) occurred in small-scale construction workplaces with less than 5 billion Korean won project budget. And those accidents related to agricultural infrastructure project (37.4%) and agricultural water development project (22.4%). In terms of work types, accidents frequently took place in form-work followed by pipe installation work, steel bar work and concrete work. The potential risks were compared with actual outbreak of accidents based on Analytic Hierarchy Process (AHP). The results show that the potential conditions of accident expected to be took place is somewhat different from the actual conditions where accidents actually happened. This implicates that risk management manuals or education needs to be adjusted by reflecting unexpected circumstances. Overall, this study is meaningful in that the results could be foundations as to strengthen risk management capacity for agricultural engineering projects.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.97-106
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• 2004

In case of tunnel construction with a shallow soil cover in cohesionless soils or highly weathered rocks, reinforcement measures are required for a tunnel stability during the tunnel construction. Recent developments show that the use of Umbrella Arch Method(UAM) as tunnel reinforcement and water cut-off in domestic projects has increased. Unfortunately, guidelines for the design and construction of UAM have not been established, only empirical designs and applications in tunnel construction have been performed so far. In this study, behaviour of the steel pipes installed on the tunnel roof was analyzed through the monitoring of bending and axial stresses of the pipes with the advance of the tunnel face. The monitoring results were used in the establishment of the loading mechanism around the pipe. This paper suggests, the guidelines used in the determination of the total length, overlapping length and lateral spacing of the reinforcing pipes obtained from the established loading mechanism.

• Journal of Korean Association for Spatial Structures
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• v.15 no.1
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• pp.65-73
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• 2015

This paper presents the structural model verification process of whole wind turbine blade including blade model which proposed in Part1 paper. The National Renewable Energy Laboratory (NREL) Phase VI wind turbine which the wind tunnel and structural test data has publicly available is used for the study. In the Part1 of this paper, the processes of structural model development and verification process of blade only are introduced. The whole wind turbine composed by blade, rotor, nacelle and tower. Even though NREL has reported the measured values, the material properties of blade and machinery parts are not clear but should be tested. Compared with the other parts, the tower which made by steel pipe is rather simple. Since it does not need any considerations. By the help of simple eigen-value analysis, the accuracy of structural stiffness and mass value of whole wind turbine system was verified by comparing with NREL's reported value. NREL has reported the natural frequency of blade, whole turbine, turbine without blade and tower only models. According to the comparative studies, the proposed material and mass properties are within acceptable range, but need to be discussing in future studies, because our material properties of blade does not match with NREL's measured values.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3A
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• pp.131-138
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• 2012

This paper aims to present accurately analytical modeling method for underpinning using uncertainty reduction, obtained from comparison between numerical analysis and Site measuring data during construction and service stages. Combination of various conditions should be considered for using numerical analysis to predict the behavior of the structure accurately, even though complexly considered the conditions, real construction should be secured the stability by applying the actual instrument measurement data because predicted results are including the considerable uncertainty. In order to secure the stability during construction, the real time instrument measurements together with numerical analysis results performed before construction state are complementary used actively. From the results of this study, the significant settlements are occurred not only in underpass structure of adjacent excavation area but also in the permanent steel pipe structures were analyzed. From the site measurement results of underpass settlement, the settlements are occurred in every stages of excavation, furthermore observed tendency is asymmetrical excavation patterns are settled more than symmetrical excavation patterns. The essential consideration points for numerical analysis are construction sequence, the direction of the existing facilities, the methods of elements modeling, the applied factors for nature of material and different results would be occurred depending upon inputting the above factors.