• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.551-556
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• 2007

In this paper, the contents of numerical in the innovative tender design of the super long-span suspension bridge to be constructed between Myodo and are introduced. The total span length of the bridge, of which the main span is the third in the world so far, reaches 2,260km, and the has the floating type girder which has no vertical points at pylon. Judging from the condition of navigation, wind climate on, and construction cost, it is inevitable to make the central span 1,545m and to the technical level applied to the structural components in the existing suspension system. To realize the innovative super long-span suspension bridge, the close numerical investigations for the structural capacity, aerodynamic serviceability, and dynamic serviceability are carried out by various tools of computational mechanics.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.237-246
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• 2017

In the present paper a new Neuro-Wavelet control algorithm is proposed based on a cost function to actively control the vibrations of structures under earthquake loads. A wavelet neural network (WNN) was developed to train the control algorithm. This algorithm is designed to control multi-degree-of-freedom (MDOF) structures which consider the geometric and material non-linearity, structural irregularity, and the incident direction of an earthquake load. The training process of the algorithm was performed by using the El-Centro 1940 earthquake record. A numerical model of a three dimensional (3D) three story building was used to accredit the control algorithm under three different seismic loads. Displacement responses and hysteretic behavior of the structure before and after the application of the controller showed that the proposed strategy can be applied effectively to suppress the structural vibrations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.338-343
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• 2005

We have evaluated the structural integrity of a sandwich composite train roof which can find a lightweight, cost saving solution to large structural components for rail vehicles in design stages. The sandwich composite train roof was 11.45 meter long and 1.76 meter wide. The reinforced frame was inserted in sandwich panels to improve the structural performance of train roof structure and had the shape of hollow rectangular box. The finite-element analysis was used to calculate the stresses, deflections and natural frequencies of the sandwich composite train roof against the weight of air-condition system. The 3D sandwich FE model was introduced to simulate the hollow aluminum frames which jointed to both sides of the sandwich train roof. The results shown that the structural performance of a sandwich composite train roof under load conditions specified was proven and the use of aluminum reinforced frame was beneficial with regard to weight savings in comparison to steel reinforced frame.

• Structural Engineering and Mechanics
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• 제69권3호
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• pp.307-315
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• 2019

This paper proposes a chattering-free sliding mode control (CFSMC) method for seismically excited structures. The method is based on a fuzzy logic (FL) model applied to smooth the control force and eliminate chattering, where the switching part of the control law is replaced by an FL output. The CFSMC is robust and keeps the advantages of the conventional sliding mode control (SMC), whilst removing the chattering and avoiding the time-consuming process of generating fuzzy rule basis. The proposed method is tested on an 8-story shear frame equipped with an active tendon system. Results indicate that the new method not only can effectively enhance the seismic performance of the structural system compared to the SMC, but also ensure system stability and high accuracy with less computational cost. The CFSMC also requires less amount of energy from the active tendon system to produce the desired structural dynamic response.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.188-195
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• 2022

Although issuing change orders is a common practice in the construction phase of any project, non-structural utility subcontractors are struggling and seek to find a way to reduce change orders. Therefore, this paper presents the analysis results on change orders to cultivate possible suggestions and solutions on how to reduce or minimize change orders in mechanical, electrical, and plumbing (MEP) works. Change orders in non-structural utility works are analyzed based on six categories such as rerouting and change of location, changes in weight, rejected design by Office of Statewide Health Planning and Development, District Structural Engineer, or the Structural Engineer of Record, unforeseen conditions, changed equipment, and owner-initiated change. The analysis findings showed that rerouting and changing location is the most significant cause, followed by unforeseen conditions. The results not only contribute to the existing body of knowledge on change order research area, but also help MEP contractors reduce the time and cost of change orders.

• 국제초고층학회논문집
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• 제12권4호
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• pp.321-333
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• 2023

Structural health monitoring is a technology or research field that extends the service life of structures and contributes to the prevention of disaster accidents by continuously evaluating the safety, stability, and serviceability of structures as well as allowing timely and proper maintenance. However, the contact-type sensors used for it require considerable time, cost, and labor for installation and maintenance. As an alternative, computer vision has attracted attention recently. Computer vision has the potential to make quality, deformation, and damage monitoring for structures contactless and automated. In this study, research cases in which computer vision was utilized for structural health monitoring are introduced, and its effects and limitations are summarized. Therefore, the applicability and future research directions of computer vision-based structural health monitoring are discussed.

• 한국건축시공학회지
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• 제12권4호
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• pp.386-392
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• 2012

In this study, life cycle cost (LCC) is analyzed according to insulation panel system type using a deterministic LCC analysis method. Through this analysis, it was found that the construction cost in the deterministic LCC analysis for Ceramic panels was low compared to the construction cost for metal and stone panels. Also, the difference in cost between the Ceramic panel and the metal panel was about 2 times. In the area of maintenance cost, it was found to be similar to the previously analyzed construction cost, in which the metal panel has the highest cost due to the high cost of construction and the frequent need for maintenance. In the case of the stone panel, a small difference in cost is shown compared with that of the Ceramic panel, but the cost is higher than the Ceramic panel. Regarding the cost of waste disposal, the Ceramic panel can reduce the cost by at least 1.5 times and up to 2 times compared to other panel systems. Finally, in the analysis of sensitivity according to changes in discount rates, the Ceramic panel and metal panel systems have a similar cost, and the cost of the metal panel is a bit larger than that of other panel systems. Thus, in the subjects used in the analysis, the Ceramic panel system shows the highest economic benefits.

• Structural Monitoring and Maintenance
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• 제10권2호
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• pp.133-154
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• 2023

Obscured structural members are mostly under-evaluated during condition assessment due to lack of visual inspection capability. Insufficient information about the integrity of these structural members poses a significant risk for public safety. Time domain reflectometry (TDR) is a novel approach in structural health monitoring (SHM). Ordinary coaxial cables "as is" without a major modification are not suitable for SHM with TDR. The objective of this study is to propose a practical and cost-effective modification approach to commercially available coaxial cables in order to use them as a "cable sensor" for damage detection with the TDR equipment for obscured structural members. The experimental validation and assessment of the proposed modification approach was achieved by conducting 3-point bending tests of the model piles as a representative obscured structural member. It can be noted that the RG59/U-6 and RG6/U-4 cable sensors expose higher strain sensitivity in comparison with non-modified "as is" versions of the cables used. As a result, the cable sensors have the capability of sensing both the presence and the location of a structural damage with a maximum aberration of 3 cm. Furthermore, the crack development can be monitored by the RG59/U-6 cable sensor with a simple calibration.

• 한국전산구조공학회논문집
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• 제30권6호
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• pp.567-576
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• 2017

본 연구는 BIM 도입 효과를 극대화할 수 있는 현장 적용성 확보에 중점을 둔 철근콘크리트 골조공사의 BIM 견적모델 작성과 BIM기반 견적 업무 프로세스를 표준화한 가이드라인을 제시하는 것을 목적으로 한다. 이를 위하여 기존 지침 및 가이드라인의 BIM 견적모델 작성 범위 및 방식을 고찰하고, 철근콘크리트공사 수량산출 견적 지침 및 기준을 분석하며, 기존 견적 방식과 BIM기반 견적 방식에 대해 비교분석한다. 이를 통하여 BIM기반 견적 업무의 표준 프로세스를 수립하고, 콘크리트/거푸집/철근 견적모델의 작성 및 수량산출 기준을 도출하며, 철근콘크리트공사 BIM기반 수량산출 및 견적 업무의 성과물 목록 및 양식을 제시한다. 본 연구를 통해 작성된 BIM 견적 가이드라인은 BIM기반의 새로운 기술환경에 대한 진입장벽을 낮추고, 견적의 정확성 극대화를 통한 원가절감을 실현하며, BIM 업무와 건설산업의 생산성과 부가가치를 증대시켜, 궁극적으로 건설사업 전 생애주기에서 생산되는 정보를 통합 관리할 수 있는 기반을 구축하고 BIM 생태계를 조성하는데 기여할 것으로 기대한다.

• 한국주거학회논문집
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• 제23권2호
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• pp.69-77
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• 2012

The purpose of this study was to explore housing cost burden of young single- or two-person households in the United States who have recently moved for job-related reasons. Total 580 households were selected from 2009 American Housing Survey public-use microdata for data analysis. The findings are as follows: (1) Targeted single-person households were characterized as younger households with higher educational attainment, lower household income, and greater proportion of renters, multifamily housing residents and households with housing cost burden than other households; (2) two-person households showed a higher income level and lower housing cost burden; (3) characteristics that showed significant influences on housing cost burden were household size, householder's age, gender, race and educational attainment, household income level and tenure type; and (4) a linear combination of household size, household income, whether or not a low-income household, residency in metropolitan area, and home structural type were found to be most efficient to predict a single- or two-person household's housing cost burden regardless of the household size.