• Magazine of the Korean Society of Agricultural Engineers
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• v.12 no.3
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• pp.2013-2018
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• 1970

Abrasion rate of coarse aggregates is an important factor to determine aggregates quality. Allowable limit of abrasion rate of coarse aggregates for concrete is 40% according to K.S. Strength and durability test of concrete with 19 efferent aggregates were made. From this test, it was found that allowable limit of abrasion rate of aggregates can be increased to 43%.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.44-50
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• 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 Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.79-86
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• 2007

Recently, as steel structures become higher and more long-spanned, construction of high-strength steels is increasing gradually. Application of high-strength steel can be possible to make a more light and economic steel structures by reducing thickness and space. To apply a high-strength steel to structure, criteria of high-strength steel for buckling is required. However, current specification is not sufficient for criteria of high-strength steels. In this paper, buckling behavior of high-strength steel truss columns with box sections is investigated by using three-dimensional elastic-plastic finite deformation analysis program. The criteria equation for allowable compressive stress of high-strength steel truss columns with box sections is proposed and confirmed the applicability. It is reasonable form analytical results that formulated equations after finding the upper limit of allowable axial direction compression stresses of high-strength steel truss columns. And new equation is suitable to buckling design of high-strength steel truss columns.

• Journal of Korean Association for Spatial Structures
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• v.3 no.3 s.9
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• pp.85-93
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• 2003

Steel, concrete and their combination materials are the most 6commonly used materials for civil engineering structural systems such as buildings, bridge structures and other structures. Recently, however, fiber reinforced polymer (FRP) composites, a relatively new composite material made of fibers and polymer resins, have been gradually used in structural systems as an alternative structural material. This paper describes a comparison of design strength equations for steel column and FRP composite column based on design philosophies. The safety factors used in allowable stress design (ASD) are relatively higher in FRP structural design than steel structural design. Column critical stress equations of FRP composites column from an experimental study can be represented by Euler elastic buckling equation at the long-range of slenderness, and an exponential form at the short-range of slenderness as defined in Load and Resistance Factor Design (LRFD) of steel column. The column strength of steel and FRP composite columns in large slenderness is independent of material strength, this result verified the elastic buckling equation as derived by Eq. (15) and Eq. (5).

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.7-22
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• 2021

In this study, inverse analysis was performed on the bi-directional axial compressive load test conducted on drilled shafts. And the bearing capacities were analyzed by numerical analysis of various pile tip ground conditions of silt clay, silt sand, sand silt, sand gravel, weathered rock, and soft rock. The bearing capacities were analyzed using the P-S method, the Davisson method, and the allowable sttlement of 25.4 mm. The minimum allowable bearing capacities analyzed by three methods were found to be 19.64 MN ~ 24.96 MN. At this time, the base resistances were sharing a 2% ~ 12% of a head load, shaft resistance were shared 88% ~ 98% of the head load. The greater the strength of pile tip was found to increase the allowable bearing capacity. However, the difference between the maximum allowable bearing capacity and the minimum allowable bearing capacity was 5.32 MN, and the increase in the allowable bearing capacity was only 27% depending on the pile tip.

• Journal of the Korean Geotechnical Society
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• v.35 no.9
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• pp.15-28
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• 2019

Long-term allowable compressive Loads of PHC piles were analyzed based on qualification tests results by 17 small and medium PHC pile producing companies and product specifications by 6 major and 17 small and medium PHC pile producing companies. At the present stage, an average long-term allowable compressive load of PHC pile was designed at 70% level from current design data, and safety factor of 4.0 was applied to long-term allowable compressive loads of PHC pile despite of its excellent quality. Most quality standards of PHC pile are specified at KS F 4306. But compressive strength test method of spun concrete is specified at KS F 2454. As a result of analyzing quality test data supplied by each manufacturer, all quality test results showed higher performances than standard values. Therefore, it was considered that the capacity of PHC pile can be used up to the maximum allowable compressive load of PHC pile when PHC pile is designed.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.89-100
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• 2019

The purpose of this study is to analyze the characteristics of bearing capacity of pre-bored super strength PHC (SSPHC) piles socketed in rocks based on dynamic load test results. Because the SSPHC piles have high compressive concrete strengths compared with those of regular high strength PHC piles, the allowable structural strengths of the SSPHC piles were increased. For optimal design of the super strength PHC piles, the geotechnical bearing capacity of the SSPHC piles should also increased to balance the increased allowable structural strength of the SSPHC piles. Current practices of pile installation apply the same amount of driving energy on both SSPHC and high strength PHC piles. As results of analyzing factors that influence bearing strength of SSPHC piles using dynamic load test, there was no relationship between SPT-N value at pile toe and end bearing capacity. But driving energy effects on end bearing capacity. In case of skin friction, driving energy had no effects. And reasonable method verifying design bearing strength is necessary because end bearing capacity is not considered sufficiently in restrike test results.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.556-561
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• 1988

Shrink-rings (Stress-rings) are used in the fabrication of dies for cold forming and powder compaction processes to increase the allowable pressures for a given die material. Optimum procedures are to minimize a die thickness under the conditions that the stress distributions in the die and stress-rings utilize fully the strength available in each of the die elements. This paper proposes a new approach, where the maximum allowable shrinking pressures are calculated on shrinkage plans in the radial direction and the fractional shrinking pressures below the maximum allowable pressures are used as the design values. Two criteria for the optimal die design are used: Maximum shear stress limit for one-piece dies and zero tensile stress limit for combined dies. A computer program, DIECOM, is developed for illustrating the computer-aided design procedures. Finally, examples for each case are presented in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.51-57
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• 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 Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.333-338
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• 2007

The concept of "Allowable Load Set (ALS)" introduced by the author allows an easy understanding of load and strength characteristics of a structure in relation to its integrity under uncertainties. Two criteria of safety are introduced: A relative safety index denotes the distance to the boundary of the ALS and a normalized safety index is a distance in terms of functional value. They have been utilized in several examples, including multi-body mechanical systems such as a biomechanical system. Both formulations amount to robust designs in the sense that designs most insensitive to uncertainties are obtained in the context of newly defined safety indices, without using any input probability information.