• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.207-220
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• 1999

Model tests were performed to investigate the failure modes in embankments on soft ground supported by piles with cap beams. In the model tests, Jumunjin standard sand was placed on simulated cap beams and soft ground. The cap beams are placed perpendicular to the longitudinal axis of the embankment. The colored sand and the Jmniin standard sand were placed one after the other above cap beams and soft ground to make lateral stripes with 3mm thickness in the embarkment. The colored sand was prepared by coating the Jumunjin sand with black lead powder. The photographs illustrate the two characteristic modes of failure in embarkments. One is the soil arching failure and the other is the punching shear failure. The failure mode depends on the height of embankment and the space between cap beams. That is, if the embankment is high enough compared with the space between cap beams, it will fail in arching failure. On the other hand if the embarkment is relatively low or the space between piles is too wide, it will fail in punching shear failure. The soil arching develops in embarkment as a semicylindrical arch with a thickness equal to the width of the cap beam. And the soil wedge developed above the cap beams remains intact during both arching and punching failures. The boundary of punching shear failure of the displaced soil mass can be defined on the basis of observation of the photographs.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.319-326
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• 2009

Two parallel wide flange built-up beams are widely used as struts in resisting lateral earth pressure because of the effectiveness in structure and construction. In a certain structural system, the reinforced concrete columns are to be placed at the intersection where two perpendicular beams cross each other, the square part of the joint being filled with concrete. In the punching shear mechanism of the beam-column joint, the radial deformation caused due to shear cracking will be constrained by the spring action of the squarely encompassed beam flanges. As a result, the punching shear strength of the joint concrete can be expected to be increased. To verify this phenomenon experiments have been performed for various constraining elements and distances between columns and constraints. Test results are compared with the approximation analysis formula which has been proposed in this study, based on the code formula. The results calculated by the proposed equation show comparatively close agreement with the punching shear strength detected from the test.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.285-289
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• 2015

With the miniaturization with both high functionality and high integrity of the probe cards, the highly precise laser punching on the zero-shrinkage high strength substrate has attracted more attention recently. Taper occurrence during laser-punching on green sheets appears as a problem in process. The size (diameter) difference between the entrance hole and the exit hole in tapered holes appeared to be inversely proportional to the hole size itself. To suppress taper occurrence, two-stage punching was adopted as the size of second hole was varied from $70{\mu}m$ to $79{\mu}m$ when punching $80{\mu}m$ via holes on the substrate with thickness of $380{\mu}m$. The minimal taper ratio of 11.9 % appeared with second hole size between 70 to $79{\mu}m$ before sintering. Taper ratio reduced to 7 % after zero-shrinkage sintering. The size difference between first hole and second hole appeared minimal when the size of second hole was 95~97 % to that of first hole.

• Journal of the Korean Geotechnical Society
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• v.26 no.3
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• pp.35-45
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• 2010

The mechanism of load transfer by punching shear in pile-supported embankments is investigated. Based on the geometric configuration of the punching shear observed in sand fills on soft ground, a theoretical analysis is carried out to predict the embankment loads transferred on a cap beam according to punching shear developed in pile-supported embankments. The equation presented by the theoretical analysis was able to consider the effect of various factors affecting the vertical loads transferred on the cap beam. The reliability of the presented theoretical equation is investigated by comparing it with the results of a series of model tests. The model tests were performed on cap beams, which had two types of width; one is narrow width and the other is wide width. Sand filling was performed through seven steps. Two types of loading pattern were applied at each filling step; one is the long-term loading, in which sand fills at each filling step were kept for 24 hours, the other is the short-term loading, in which sand fills at each filling step were kept for 2 hours. The vertical loads measured in all model tests show good agreement with the ones predicted by the theoretical equation. Finally, the predicted vertical loads also show good agreement with the vertical loads measured in a well-instrumented pile-supported embankment in field, where cap beams were placed on too wide space.

• 소프트웨어공모대전
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• s.4
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• pp.171-185
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.231.2-231
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• 2002

• The monthly packaging world
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• s.356
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• pp.88-93
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• 2022

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.71-74
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• 2007

Substitution of the stacked antenna for the normally pressed antenna in the mobile phone was tried for the purpose of decreasing its size. However, reduced size resulted in the difficulties obtaining the targeted characteristics with the bandwidth over 70MHz. The cross-section of the vias in the low temperature co-firing ceramics process was studied to find out effects on the bandwidth characteristics. Circular and rectangular cross-section of the via beneath different types of antenna patterns were simulated. Better bandwidth characteristics were acquired for the larger diameter of the circular section and for the rectangular section as the cross-section area increased. From the viewpoint of the shape of the cross-section, rectangular area showed better characteristics than the circular area with the same longest length in the cross-section.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.39-55
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• 1999

Geotextile composites to improve the weather ability were composed of recycled polyester geotextile with carbon black as ultraviolet stabilizer and polypropylene geotextile by needle-punching method, and evaluated physical properties, ultraviolet resistance and chemical stability. Retention ratio of tensile properties of non woven polypropylene geotextiles were decreased about 50% by the exposed condition with ultraviolet but those of geotextile composites were slightly decreased than polypropylene geotextiles. Geotextile composites which have larger weights of polyester geotextile were more stable against ultraviolet. For chemical stability, the changes of tensile properties of geotextile composites were in the range of -20~＋10% at the various chemical conditions.

• International Journal of Concrete Structures and Materials
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• v.6 no.2
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• pp.111-121
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• 2012

The research presented in this paper analytically examines the fire performance of flat plate buildings. The modeling parameters for the mechanical and thermal properties of materials are calibrated from relevant test data to minimize the uncertainties involved in analysis. The calibrated models are then adopted to perform a nonlinear finite element simulation on a flat plate building subjected to fire. The analysis examines the characteristics of slab deflection, in-plane deformation, membrane force, bending moment redistribution, and slab rotational deformation near the supporting columns. The numerical simulation enables the understanding of structural performance of flat plate under elevated temperature and, more importantly, identifies the high risk of punching failure at slab-column connections that may trigger large-scale failure in flat plate structures.