• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.123-128
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• 2007

Already, core wall construction method for apartment wall structure and general building special areas applied the engineering method's appropriate examination. Also, trial and error depending on slip-form method is a good examination opportunity to consider. In the present paper's slip-form engineering method l)Casting concrete to slab in sliding 2)RC structure + SRC structure (part of segment) 3)Inside segment variation(straight line-diagonal-circle) are together while determining whether it is possible not to carry out actual construction work on the structure. Finally, small problems continuously appear on actual slip-form method application, design and engineering, starting with planning thoroughly the field examination and diagnosing the atmosphere, minimizing cost, secure work safety facilities characterized by good quality, slip-form research extension, development and decision-making.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.184-192
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• 2010

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete (RC) structures, and the concept of the effective moment of inertia has been generally used for its estimation. However, the actual service load applied on an existing RC beam may not be easily obtained, for which the estimation of beam deflection by existing methods can be difficult to obtain. Therefore, based on the correlation between cracks and deflection in a RC beam, this study proposed a method to estimate the deflection of RC beams directly from the condition of cracks not using the actual loads acting on the member as its input data. The proposed method extensively utilized the relationships among sums of crack widths, average strains, and curvatures, and modification factors obtained from regression analysis were also introduced to improve its accuracy. The deflections of members were successfully estimated by the proposed method independent from applied loads, which was also easy to apply compared to the existing methods based on the effective moment of inertia.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.150-150
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• 2015

최근 하천의 수위조절 기능을 수행하는 보 건설이 증대되고 있다. 보는 원활한 용수공급을 위해 필수적인 구조물이지만, 하천 횡단 구조물의 특성상 유사퇴적에 의한 통수단면적 감소, 홍수위험도 증가, 수질악화 등의 문제를 내포하고 있다. 이를 해결하기 위해 유사시 유사배출이 가능하고 수문개도를 통한 통수단면적 조절로 홍수위험도를 감소시킬 수 있는 가동보를 고정보와 병용해서 적용하는 추세이다. 가동보는 수문 운영 방식에 따라 하류의 흐름상태가 다양하게 나타나며, 흐름 상태에 따라 하도 및 구조물에 미치는 영향도 달라진다. 그러나 기존 가동보 및 보 하류 구조물의 설계 시 일반적으로 수문 운영조건을 고려하지 않고, 홍수위 조건을 최악조건으로 고려하는 한계가 있다. 본 연구에서는 3차원 수치모델(FLOW-3D)을 활용하여 가동보의 운영에 따라 발생하는 다양한 흐름조건이 보 하류에 미치는 영향을 검토하고자 한다. 수치모델의 검증을 위해 기존 수행된 수리실험과의 비교를 수행하였고, 홍수위 조건(수문 전문개도) 및 관리수위 조건(수문 일부개도)에서 수치모의를 수행하였다. 보 상류, 직하류, 도수종점에서 발생하는 단면최대유속, 바닥전단 응력, Froude 수 등의 수리특성을 분석하였고, 상하류간 수심차와 수문개도높이의 비와 접근유속과 보 직하류에서 유출되는 유속의 비로 무차원화하여 관계를 분석하였다. 또한 홍수위 조건과 관리수위 조건에서 발생하는 수리특성을 비교함으로써, 보 하류부 구조물 설계 시 반영할 최악조건을 예측하고, 수문운영이 하류부에 미칠 수 있는 영향을 가시적으로 확인할 수 있었다. 향후 상류의 유량조건 및 상하류 수위차에 따른 가동보의 운영조건이 보 하류의 안정성 지표산정에 활용될 수 있기 위해 보다 심도있는 연구 수행이 필요하다.

• The Journal of Korean Institute of Information Technology
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• v.15 no.12
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• pp.165-171
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• 2017

This paper proposes a method of support-generation using morphological image processing instead of geometric calculations. The geometric computational cost is dependent on the shape, but our method is independent on the shape. For obtaining the external support area for extrusion shape, we represents morphological operations between two sliced layer images and shows results of each operation stages. Internal support area is evaluated from erosion and opening operations with the sliced-layer image. In these support areas, the supporter image is generated using the designed support structures. Also, we made a DLP printer and the STL model included supporter-structure is printed by the DLP printer. We confirmed the necessity of support-generation method with the support structures individually dependent on materials by looking at the printed results.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.171-186
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• 2010

It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than in the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system or change of ground condition happen during construction process, lots of axial force can be induced in some struts, which threaten the safety of construction. This paper introduces two examples of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, which were measured in the sections of two examples that are 50 meters apart in one construction site and have almost similar design and construction conditions were analysed, the similarity and difference between measurement results of two examples were compared and investigated. This article aims to improve and develop the technique of design and construction in future projects having similar ground condition and supporting method.

• Journal of Korean Society of Steel Construction
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• v.24 no.5
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• pp.535-547
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• 2012

PSRC column is a concrete encased steel angle column. In the PSRC column, the steel angles placed at the corner of the cross-section resists bending moment and compression load. The lateral re-bars welded to steel angles resist the column shear and the bond between the steel angle and concrete. In the present study, current design procedures in KBC 2009 were applied to the flexure-compression, shear, and bond design of the PSRC composite column. To verify the validity of the design method and failure mode, simply supported 2/3 scaled PSRC and correlated SRC beams were tested under two point loading. The test parameters were the steel angle ratio and lateral bar spacing. The test results showed that the bending, shear, and bond strengths predicted by KBC 2009 correlated well with the test results. The flexural strength of the PSRC specimens was much greater than that of the SRC specimen with the same steel ratio because the steel angles were placed at the corner of the column section. However, when the bond resistance between the steel angle and concrete was not sufficient, brittle failures such as bond failure of the angle, spalling of cover concrete, and the tensile fracture of lateral re-bar occurred before the development of the yield strength of PSRC composite section. Further, if the weldability and toughness of the steel angle were insufficient, the specimen was failed by the fracture of the steel angle at the weld joint between the angle and lateral bars.

• Journal of the Korea Concrete Institute
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• v.17 no.3 s.87
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• pp.393-400
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• 2005

Steel encased composite columns have been used for buildings and piers of bridges. Since the column section for the pier is relatively larger than that of building columns, economical steel ratio needs to be investigated for the required performance. Composite action between concrete and embedded steel sections can be obtained by bond and friction. However, the behavior of the column depends on the load introduction mechanism. Compression can be applied to concrete section, steel section and composite section. In this paper, experiments on shear strength of the steel encased composite column were performed to study the effect of confinement by transverse reinforcements, mechanical interlock by holes, and shear connectors. Bond strength obtained from the tests showed considerably higher value than the design value. Confinement, mechanical interlock and stud connectors Increased the shear strength and these values can be used effectively to obtain composite action of Steel Reinforced Concrete(SRC) columns.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.331-341
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• 2012

Granitoid rocks are generally high-quality rock from a geotechnical perspective, because they rarely contain systematic joints or fragmented fault zones. Although the rock type at the Sanhak site is granite, a collapsed slope has a deep soil layer and shows no residual structures such as discontinuities or faults; surface avalanches from this slope can be observed in several places. To study the stability of this slope, we investigated rainfall duration, variation in pore-water pressure, and the factor of safety considering three cases (current cross-section, initial planning cross-section, revised planning cross-section). With increasing duration of rainfall, the groundwater level rises, up to 20 m in height from ground surface. In the initial planning cross-section, safety was secure for rainfall of 2 days duration, but inadequate for rainfall of 4 days duration. In the revised planning cross-section, however, safety factors were secure for rainfall of 4 days duration. Therefore, to ensure permanent stability at the Sanhak site, a slope degree of 1:1.8 should be maintained during cutting.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.33-42
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• 2002

Ground reaction curve is a very important information for evaluating the side wall displacements and installation time of the tunnle support. The ground reaction curve can be estimated by analytical closed form solutions derived on the supposition of circular section and isotropic stress condition. The conditions of stress field and tunnel configurations, however, are quite different in practice. Therefore, it is necessary to investigate the effects of stress anisotropy and tunnel configurations in order to use simply in practical design. This paper describes a study of influence factors in the ground reaction curve. In order to evaluate the applicability of analytical closed form solution in practical design, two sets of parametric studies were carried out by numerical analysis in elastic tunnel behaviour: one set of studies investigated the influence of the K and the other set investigated the influence of the tunnel configurations such as circular and horse-shoe shape. In the studies, K value varies between 0.5 and 3.0, initial ground vertical stress varies between 5～30MPa far each K values. The results indicated that the self-supportability of ground is larger in the ground having lower K value. However, it is suggested that the applicability of closed form solution may not be adequate to determine directly the installation time of the support and self-supportability of ground. It is necessary to consider stress anisotropy and tunnel configurations.

• Fire Science and Engineering
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• v.25 no.6
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• pp.83-88
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• 2011

This study presented the structure and characteristics of vinyl cords used for wiring electric equipment and appliances and analyzed the photographs of damaged flat-type vinyl cords (VFF, $1.25mm^2$) and the metallic cross-sectional structure of melted conductors. Normal VFFs were made by twisting several strands together and the surface of the conductor was red brown. In addition, from the analysis of the metallic structure of the conductor, it was found that its grains had been elongated. The surface of a VFF damaged by normal flame showed no sheen with carbonized insulation material fused on the conductor surface. In addition, from the analysis of the cross-sectional structure of the melted area, it was found that voids of a certain shape were formed on it but that the cord's own elongation structure could not be checked. The cross-sectional analysis of the melted conductor damaged by the external flame applied to a VFF to which electric current was being applied showed no elongation structure for each cord, and revealed that irregular voids and a columnar structure had grown. The surface of the VFF damaged by overcurrent was uniformly carbonized and the cross-sectional structure analysis of the melted conductor revealed that the dendritic structure had grown. The analysis of the characteristics of the VFF melted by short-circuit showed that even though some part of the surface was contaminated, it showed little sheen and that the area rebounded by melting was round in shape. In addition, the cross-sectional structure analysis using a metallurgical microscope showed the boundary surface and columnar structure and revealed an amorphous structure like normal copper at areas other than the melted conductor.