• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.409-410
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• 2010

Since the 1980s with the development of construction techniques over 100 floors above 50 floors of the skyscraper was in progress. The advent of high-rise buildings due to an increase in foundation thickness was inevitable. at the moment, construction period and economic efficiency can be improved from decrease of the foundation thickness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.981-986
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• 2003

In order to investigate the possibility of processing of brittle material by ball impact, the effects of boundary conditions about impact damage of soda-lime glass by small spheres were evaluated experimentally. It was investigated that crack appearance developed in soda-lime glass with boundary conditions of without sealing, single-sealing and double-sealing by impact velocity. The double-sealing was most effective in the development of perfect cone than other boundary condition. In case of double-sealing condition, PVC and Polyurethane sealing were more effective in producing a perfect cone formation than other sealing materials. The impact velocity range over which perfect cones were formed was influenced by both the contact area and diameter of impact particle.

• Structural Engineering and Mechanics
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• v.52 no.4
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• pp.767-786
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• 2014

This paper presents the design of reinforced concrete circular footings subjected to axial load and bending in two directions using a new model. The new model considers the soil real pressure acting on contact surface of the circular footings and these are different, with a linear variation in the contact area, these pressures are presented in terms of the axial load, moments around the axis "X" and the axis "Y". The classical model takes into account only the maximum pressure of the soil for design of footings and it is considered uniform at all points of contact area. Also, a comparison is presented in terms of the materials used (steel and concrete) between the two models shown in table, being greater the classical model with respect the new model. Therefore, the new model is the most appropriate, since it is more economic and also is adjusted to real conditions.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.597-602
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• 2006

Bulk plastic forming characteristics were studied for the magnesium alloy, AZ31 in warm backward extrusion. Effects of process conditions such as extrusion ratio, forming temperature, and punching speed were investigated respectively. Variation of microstructure induced by the warm backward extrusion process was observed. Microstructure of the work piece showed evidences of recrystallization under the experiment conditions. It is estimated that in specific punch speed region fast stroke accelerates recrystllization and reduces the forming load.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.32-35
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• 1998

The material properties and forrnabilities of tailored blanks are evaluated by experimental tests. In the tensile test, the gradient of strength coefficients of the heat affected zone associated with the welded line width represents the quality of a welded part. In the hemispherical dome punching test, the plane strain state of the welded line is observed. In the squared cupping test, the thin side is stretched more than the thick side in the stretch mode, while both sides are similarly stretched in the draw mode. In the 2D draw test, FLCo is measured in a simple manner and the forming defects of the tailored blanks with the same thickness are found.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.791-796
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• 2000

Purpose of this study is to analyze the characteristics and reinforcement effects of restored the RC bridge deck with small precast panel through static load tests and to provide the basic information for the damaged slab decks. In the tests for realizing movement of general RC bridge slabs, 6 samples are prepared and tested. All reinforced samples are restored with 1 or 2-layers precast panels by epoxy mortar. The movement of restored slabs is analyzed and compared with the behavior of non-restored slabs. In result of these tests, tension cracks due to bending moment are show, and after static load test there happens finally a punching shear failure, which is the general type of RC bridge failure. The tests show that restoration of the RC slab results in increasing of loading capacity about 30~50% an restoring panels are stick to slab and moving with slab under loading test.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.415-420
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• 2003

This Study is performed to analyze the behavior of inverted T-shaped Composite Basement Wall(CBW). For this, it is purposed to analyze the failure mechanisms of inverted T-shaped composite basement wall and propose the method of evaluating strength for design. The failure mechanisms would be devided into 4 type mechanisms from previous experimental results, that is hanger failure, punching shear failure, flexural failure and the buckling of H-pile. A strength evaluation procedure for CBW is induced by analyzing respective failure mechanism. Then, the strength for actual structure consisted of inverted T-shaped composite basement wall was evaluated and the expected failure mechanism was determined.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.421-426
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• 2003

For the replacement of deteriorated concrete decks or wider-span slab, composite slab could be very attactive due to higher stiffness and strength. Based on the previous research, a modified I-beam composite hollow slab was suggested. In order to investigate the static flexural behavior of the proposed composite slab and to suggest its flexural design method, experiments were performed. Judging from the tests, a composite slab with I-beam having a semi-circle hole showed better structural performance. The effect of web details on the flexural stiffness was negligible. Flexural stiffness, ultimate strength, and ductility of the composite slabs were significantly greater than the RC slab due to composite action. While the failure of the RC slab was punching shear failure, the composite hollow slab showed flexural cracking and failure by yielding of the I-beams and crushing of concrete. Therefore, the current one-way design concept is appropriate for the design of I-beam composite hollow slab.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.518-523
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• 2003

In domestic composite bridges, it has been reported that most failure is occurred in deck and the type of failure was mainly punching shear failure. Therefore to increase a life of bridges and reduce maintenance costs, an improvement of a durability of slabs is needed. In these respects, precast deck can be very useful. In a composite bridge with precast decks, it is required to notice behavior of transverse joints between decks. In this paper, bending tests of precast deck with loop joints were conducted. From the results, the validity of loop joints for continuity of deck was observed and especially an interval of loop joint, diameter of loop and reinforcement were checked.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.792-796
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• 2000

With the development of micro machining, it becomes an important part to fabricate an electrode which has tens of ${\mu}m$ or less. There are two methods to get a narrow hole; non-contact type such as EDM(Electro-discharge machining) and contact type such as punching. A punch which has a tapered shape with a cylindrical tip is fabricated in this paper. To make this punch, a method which was used to fabricate a cylindrical shape by electrochemical process was applied. The control factors for the shape and their limits are verified through an experiment.