• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.413-416
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• 2006

This paper presents the analytical results on the heat of hydration and induced thermal cracking of the wall elements in LiNAC that is a radioactive shield concrete structure. This wall elements measuring 1.2 m in thickness and 32 m in length tend to exhibit thermal cracking due to heat of hydration and high constraint effects caused by slab element located in the lower part of structure. In this analysis, four different construction stages were considered to find out the most effective concrete casting method in terms of thermal stress. Among the construction methods adopted in this analysis, the method of installation of construction connection measuring 1.2 m at the both side of wall elements was very effective way to control the thermal stress, resulting in increase thermal cracking index of wall elements in LiNAC structure. Finally, the wall elements in LiNAC structure was cast successfully according to the proposed construction method.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.51-66
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• 2003

최근 용지매입의 제한과 자연환경훼손의 최소화를 도모하는 사회적 환경으로 인해 대단면 근접병설터널 계획이 점차 증가하고 있다. 지금까지는 주로 중앙벽체부의 지지기능을 활용한 2Arch터널의 형태로 도심지 지하철의 정거장이나 고속도로의 일부구간에 계획되고 있으나, 대단면 근접병설터널에 대한 시공실적 및 설계사례가 부족한 국내에서는 이에 대한 역학적 거동과 합리적 시공방안에 대한 연구가 미흡한 실정이다. 따라서, 대단면 근접병설터널에 대한 국내·외의 설계 및 시공사례를 정리·분석하므로서 차후 제한된 구간에서의 터널계획시 합리적인 설계 및 시공이 되고자 하였다. 또한, 최근 도심지 구간에 계획중인 터널의안정성 검토 사례를 중심으로 터널 및 인접구조물, 중앙필러부 및 콘크리트 라이닝에 대한 상세 안정성 검토방법을 고찰함으로써 기존 병설터널의 거동특성과는 구별되는 대단면 근접 병설터널의 안정성 평가기법에 대한 방향을 제안하였다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.148-149
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• 2021

In Japan, ultra-low shrinkage concrete has been developed and commercialized to control drying shrinkage cracks to the limit. However, in the case of South Korea, the study on this technology has not yet been conducted in earnest. Therefore, the study was conducted for the development of ultra-low shrinkage concrete to control the drying shrinkage crack of concrete to the limit, and in this study, after determining the mixture of ultra-low shrinkage concrete, a wall type mock-up specimen was produced to observe the shrinkage behavior of ultra-low shrinkage concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.659-675
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• 2006

Recently, significant progress has been made in performance-based engineering methods that rely mainly on nonlinear static seismic analysis procedures. The Capacity Spectrum Method (CSM) and the Displacement Coefficient Method (DCM) are the representative nonlinear static seismic analysis procedures. In order to evaluate the applicability of the procedures to the seismic evaluation and design process of new and existing structures, the accuracy of both CSM and DCM should be evaluated in advance. The accuracy of seismic responses by the nonlinear static procedures is evaluated in comparison with the shaking table test results for the structural wall specimen subjected to the far field and near field earthquakes. Also conducted are comparative studies where the shaking table test results are compared with those from nonlinear dynamic analysis procedures, i.e., Single-Degree-of-Freedom (SDOF), equivalent SDOF and Multi-Degree-of-Freedom (MDOF) systems.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.49-56
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• 2023

This study proposed a damage location estimation method for automated image-based port infrastructure inspection. Memory efficiency was improved by calculating the homography matrix using feature detection technology and outlier removal technology, without going through the 3D modeling process and storing only damage information. To develop an algorithm specialized for port infrastructure, the algorithm was optimized through ground-truth coordinate pairs created using images of port infrastructure. The location errors obtained by applying this to the sample and concrete wall were (X: 6.5cm, Y: 1.3cm) and (X: 12.7cm, Y: 6.4cm), respectively. In addition, by applying the algorithm to the concrete wall and displaying it in the form of an exterior damage map, the possibility of field application was demonstrated.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.465-474
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• 2014

This is a comparative study that shows the overall environmental impacts from concrete structures when different compressive strength of concrete applied to structural systems having the same reference flow with different durability. A total of 24 MPa, 40 MPa and 60 MPa cases is analyzed to define the characteristic using end-point perspective LCA methodology including the stages of production, construction, maintenance and disposal. As results, global warming, non-renewable energy and respiratory inorganics problems are the major issues for assessing environmental impacts of concrete products.

• Journal of the Korea Institute of Building Construction
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• v.23 no.2
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• pp.197-207
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• 2023

Concrete is a widely used material due to its excellent compressive strength and durability. However, depending on the surrounding environment and the characteristics of the materials used in the construction, various defects may occur, such as cracks on the surface and subsidence of the structure. The detects on the surface of the concrete structure occur after completion or over time. Neglecting these cracks may lead to severe structural damage, necessitating regular safety inspections. Traditional visual inspections of concrete walls are labor-intensive and expensive. This research presents a deep learning-based semantic segmentation model designed to detect cracks in concrete walls. The model addresses surface defects that arise from aging, and an image augmentation technique is employed to enhance feature extraction and generalization performance. A dataset for semantic segmentation was created by combining publicly available and self-generated datasets, and notable semantic segmentation models were evaluated and tested. The model, specifically trained for concrete wall fracture detection, achieved an extraction performance of 81.4%. Moreover, a 3% performance improvement was observed when applying the developed augmentation technique.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.621-637
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• 2006

Although the approaches implementing strut-tie models are the valuable tools for designing discontinuity regions of structural concrete, the approaches of the current design codes have to be improved for the design of structural concrete subjected to complex loading and geometrical conditions because of the uncertainties in the selection of strut-tie model, in the use of an indeterminate strut-tie model, and in the effective strengths of struts and nodal zones. To improve the uncertainties, a grid struttie model approach is proposed in this study. The proposed approach, allowing to perform a consistent and effective design of structural concrete, employs an initial grid strut-tie model in which various load combinations can be considered. In addition, the approach performs an automatic selection of an optimal strut-tie model by evaluating the capacities of struts and ties using a simple optimization algorithm. The validity and effectiveness of the proposed approach is verified by conducting the analysis of the four reinforced concrete deep beams tested to failure and the design of shearwalls with two openings.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.45-55
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• 2022

Because boundary confinement details proposed in the current design standards are significantly inferior in workability and production quality, it is necessary to develop boundary confinement details of RC structural walls that are capable of ensuring seismic performance and workability. With the recent development of the wire rod manufacturing technology, various pre-fabricated continuous hoop details can be manufactured. In this study, an analysis was conducted on the moment-curvature relationship of RC structural walls to which the pre-fabricated continuous hoop details were applied. According to the nonlinear cross-section analysis, the RC structure wall to which the details of the pre-fabricated continuous hoop details are applied can ensure seismic performance as the area of the pre-fabricated continuous hoop increases. Based on these research results, when applying the pre-fabricated continuous hoop in detail, it is necessary to secure the area of the pre-fabricated continuous hoop as much as the area of the existing boundary confinement.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.14-20
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• 2008

In this numerical study, the leakage safety of the LNG tank in which is constructed by membrane inner tank-plywood-polyurethane form-plywood-prestressed concrete structures has been presented for four leakage analysis models. The LNG leak criterion of the tank wall with a storage capacity of $200,000\;m^3$ is analyzed based on the thermal resistance technique. This means that if the cryogenic temperature of a leaked LNG is detected at the outer side of the PC wall, it may be leaked through the wall thickness of the tank. The calculated results based on the thermal resistance method between two walls show that the plywood, PUF, and another plywood walls may block the leakage of the leaked LNG even though the strength of these walls is already collapsed by a leaked LNG pressure. But, the leaked LNG may pass the thickness of the prestressed concrete wall for a period of elapsed time even though the PC outer tank supports the leaked LNG pressure. Thus, the PC outer tank may extend the leakage time of a leaked LNG.