• International Journal of Highway Engineering
• /
• v.10 no.4
• /
• pp.269-279
• /
• 2008

This study was conducted to develop the design methodology of transverse post-tensioning for the prestressed concrete pavement (PSCP). The transverse stress distribution was analyzed when the transverse anchor spacing changed. The tensile stress distribution in the PSCP slab due to the environmental and vehicle loads was also investigated. The reasonable methods were discussed to determine the design loads including environmental and vehicle loads and the PSCP allowable tensile stress used for the basis of the selection of the stress application amount from the tensioning. The results of this study showed that as the transverse anchor spacing increased, the range of the stress loss became larger and the stress loss was significant near the shoulder. The design of the transverse post-tensioning can be performed by obtaining the stresses under the design loads and by considering the allowable tensile stress; however, the tensile stresses at different locations such as the shoulder, wheel pass, and slab interior should also be checked and kept below the allowable tensile stress.

• Architectural research
• /
• v.9 no.1
• /
• pp.31-37
• /
• 2007

This study presents the so-called Modified Allowable Stress Design (MASD) method for structural designs. The objective of this study is to qualitatively estimate uncertainties of tensile steel member's cross-sectional structural designs and find the optimal resulting design which can resist all uncertainty cases. The design parameters are assumed to be interval associated with lower and upper bounds and consequently interval methods are implemented to non-stochastically produce design results including the structural uncertainties. By seeking optimal uncertainty combinations among interval parameters, engineers can qualitatively describe uncertain design solutions which were not considered in conventional structural designs. Under the assumption that structures have basically uncertainties like displacement responses, the safety range of resulting designs is represented by lower and upper bounds depending on given tolerance error and structural parameters. As a numerical example uncertain cross-sectional areas of members that can resist applied loads are investigated and it demonstrates that the present design method is superior to conventional allowable stress designs (ASD) with respect to a reliably structural safety as well as an economical material.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.111-114
• /
• 1999

SFRC(Steel Fiber Reinforced Concrete) has advantage of crack resistance and ductility failure behavior. But the study which investigated about effect of steel fiber under bearing stress is not to be enough, and it does not be sure of criterion of SFRC for allowable bearing stress formula in internal specification. The purpose of this study is to clear the influence of SFRC on the bearing capacity and ductility of material through static loading test. additionally, arrive an allowable bearing stress formula for SFRC and examine mechanical behaviro by the 3-D finite element analysis.

• Journal of the Korean Society of Safety
• /
• v.18 no.4
• /
• pp.44-50
• /
• 2003

Design method for involute bevel gears is developed. The developed gear design system can design the optimized gear that minimize the number of pinion teeth with face tooth. Method of optimization is MS(matrix search) which is developed from this study. Design variables are pressure angle 20., transmitted power, gear volume, gear ratio, allowable contact stress and allowable bending stress. etc. Gears design method developed this study can be applied to the plane, helicopter, printer, machine tools.

• Journal of Korea Water Resources Association
• /
• v.41 no.2
• /
• pp.137-147
• /
• 2008

Critical and allowable shear stress acting on the mattress revetment, is presented in this study. First of all, shear stress at each spot is computed when the hydraulic power act on the waterway. Secondly, median diameter of the filling rocks is computed using shear stress and Shields coefficient which are used to decide the critical motion of the particle. Finally, the range of critical and allowable shear stress is estimated which meet the particle stability and indicated that the mattress is a stable hydraulic structure in comparison with the riprap. Therefore the required median diameter of riprap is three times higher than that of mattress. Contrarily, this study also analyzed that resisting power of mattress to shear stress is three times higher than that of riprap on the same size.

• Plant Journal
• /
• v.8 no.2
• /
• pp.52-58
• /
• 2012

Pipe means the connection of the tube in order to transfer fluid from one device to another device. The piping stress analysis is to analyze the structural stability considering the location and the features of piping support after completing the piping design, The allowable stresses comply with the requirements of the relevant standards by examining whether the support of the function and location of pipe or re-operation is confirmed. Allowable stresses are to make sure that the maximum stress should not exceed the allowable stress presented in the ASME B31.1 POWER PIPING code. ASME B31.1 POWER PIPING code ensures a smooth stress analysis can be performed during the initial pipe stress analysis as provided in the case of straight pipe to the horizontal distance between the supports. However, because there is no criteria set in the case of curved pipe, the optimum pipe supporting points were studied in this paper. As mentioned about the curved pipe, loads applied to the support of the position of 17% and 83% of the position relative to the elbow part have results similar to the load acting on the support of straight pipe.

• Journal of the Korean Society of Safety
• /
• v.16 no.3
• /
• pp.99-105
• /
• 2001

This paper presents results km a series of model tests oil vertically loaded single piles to compare the behaviors of H and pipe piles under the same ground condition. The aims of this paper were to compare the bearing capacity of H-pile md pipe piles under in the same ground condition and to estimate the effect of gravity acceleration and relative soil density. Relative density of soil were made to be 40%, 80% and embedded length of pile on sand was increased by 10, 12, 14, 16 times of the diameter of pile, respectively. As a results of test series, allowable load of H-pile is from 6.4% to 18.2% larger than allowable load of pipe pile in relative density 80% and from 9.1% to 39.4% larger than allowable load of pipe pile in relative density 40%. As a results of numerical analysis, we were predicted behaviour of stress-displacement of pile with model test. In the case of relative density 80% and 40%, bearing capacity of H pile represent from 17.74% to 18.6% larger than allowable load of pipe pile.

• Tribology and Lubricants
• /
• v.27 no.3
• /
• pp.147-155
• /
• 2011

The ceramic coatings are excellent materials of cutting tools and sliding parts. To evaluate the wear characteristics of very thin ceramic coated layer, it is very important to investigate its wear process microscopically. An effective method for investigating the wear of a thin layer is the observation of wear process in microscopic detail using in-situ system. In this study, using the SEM Tribosystem as in-situ system, the microscopic wear mode of TiN coatings was investigated in repeated sliding. As results, four modes were observed for TiN coatings: Ploughing, powder formation, flake formation and coating delimitation. The observation of the microscopic wear by in-situ system can clarify the allowable stress of TiN coating.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.4
• /
• pp.51-57
• /
• 1998

It is common to assume identical allowable safety factors in static strength defined by mean stress and in fatigue, defined by stress amplitude. Under the load with asymmetrical cycles the safety factor is not the same. In this paper, with the consideration of unequal allowable safety (actors a general method for estimating fatigue reliability of a machine element under a combined state of stress is derived based on the theory proposed by Prof. Kececioglu and a normal distribution. The calculation of fatigue reliability fur limited life is discussed with example.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.11a
• /
• pp.239-241
• /
• 2004

Stress intensity factor of semi-circular crack front was calculated by FEM, and also allowable crack size which doesn‘t break out the fracture by SCC in residual stress field of STS materials. Allowable crack size was increased with compressive residual stress provided by shot peening on material surface, and with magnitude of compressive residual stress for depth direction.