• 비파괴검사학회지
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• 제20권4호
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• pp.290-295
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• 2000

최근 역타시공법 등에 의한 콘크리트 구조물의 시공이 증가 추세에 있다. 이 경우, 자주 발생되는 신 구타설 콘크리트 시공이음부의 공극은 향후 구조물의 구조적인 특성과 내구성 등에 큰 영향을 미치게 된다. 그러나 현재 제안되고 있는 비파괴 검사법으로는 효과적으로 이음부 공극을 평가하기에 많은 한계가 있다. 본 연구에서는 시공이음부의 콘크리트 충전상태를 평가하기 위해 철골철근 콘크리트와 무근 콘크리트 시험체내에 공극을 모의제작한 후, 초음파속도 측정을 실시하고, 화상처리기법을 이용하여 비교적 용이하게 해석 가능한 방법에 대해 검토하였다.

• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.313-322
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• 2020

The recognition of the risk hazards is a vital step to effectively prevent accidents on a construction site. The advanced development in computer vision systems and the availability of the large visual database related to construction site made it possible to take quick action in the event of human error and disaster situations that may occur during management supervision. Therefore, it is necessary to analyze the risk factors that need to be managed at the construction site and review appropriate and effective technical methods for each risk factor. This research focuses on analyzing Occupational Safety and Health Agency (OSHA) related to risk zone identification rules that can be adopted by the image recognition technology and classify their risk factors depending on the effective technical method. Therefore, this research developed a pattern-oriented classification of OSHA rules that can employ a large scale of safety hazard recognition. This research uses joint reasoning of risk zone Identification and numeric input by utilizing a stereo camera integrated with an image detection algorithm such as (YOLOv3) and Pyramid Stereo Matching Network (PSMNet). The research result identifies risk zones and raises alarm if a target object enters this zone. It also determines numerical information of a target, which recognizes the length, spacing, and angle of the target. Applying image detection joint logic algorithms might leverage the speed and accuracy of hazard detection due to merging more than one factor to prevent accidents in the job site.

• 한국강구조학회 논문집
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• 제16권3호통권70호
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• pp.377-385
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• 2004

본 논문에서는 강판-콘크리트 벽체구조에 부착되는 기기를 지지하기 위하여 설치되는 지지대와 벽채와의 접합 성능을 파악하기 위하여 구조실험 및 유한요소해석을 수행하였다. 구조실험은 9개의 시험체를 제작하여 파괴모드 및 최대내력을 파악하였으며 유한요소해석모델을 작성하여 이를 실험결과와 비교 검증한 후 강판두께, 스터드 볼트 간격, 지지대의 위치 및 크기 등의 영향인자가 벽체 접합부의 거동 및 내력에 미치는 변화를 살펴보았다. 해석 시험체의 하중-변형의 관계로부터 시험체의 항복내력 및 최대내력을 정의 하였으며 향후 항복선 해석을 위한 토대를 마련하였다.

• 한국강구조학회 논문집
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• 제22권5호
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• pp.435-443
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• 2010

현행 송전강관철탑의 경우 허용응력 설계개념을 도입한 철탑설계기준을 적용하여 설계, 제작되고 있다. 이 철탑설계기준의 압축재의 설계 강도 결정은 압축재의 허용좌굴응력에 의하여 결정되고 있으나 이는 접합부의 내력을 고려치 않은 값이다. 부재가 압축좌굴내력에 도달하기 전에 접합부의 변형으로 인하여 국부변형에 의한 접합부 파괴가 발생할 수 있다. 따라서 본 연구에서는 접합부의 보강형태별로 접합부내력을 산출하고 이를 데이터베이스화한 후 지난 연구에서 도출한 등가비선형해석기법의 부재내력과의 상호 비교를 통하여 부재파괴와 접합부파괴의 선행 여부를 판별할 수 있는 실용적인 평가 및 설계 기법을 제시하였다.

• 한국강구조학회 논문집
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• 제11권1호통권38호
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• pp.23-31
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• 1999

결합부위의 해석을 위하여, 계산 효율과 정확성이 모두 뛰어난 단순모델의 사용이 필요한 경우가 많다. 이 단순모델은 결합부위의 특성을 잘 묘사하는 파라미터들로 구성된다. 이들 파라미터의 값은 실험을 통하여 얻어지게 된다. 따라서 단순모델은 실험에서 사용된 하중하에서는 결합부위의 거동을 잘 묘사하지만, 그외 다른 하중하에서는 결합부위의 거동을 어느 정도 구현할지 알 수 없다. 따라서 단순모델의 정확성을 객관적으로 얻을 수 있는 방법이 필요하게 된다. 본 연구에서는 역최적화 (antioptimization) 개념으로 최악의 하중조건을 정의하여, 이 하중하에서 단순모델의 정확성을 평가하는 방법을 제시하였다. 최악의 하중조건 하에서, 용접으로 체결된 3차원 결합부위의 단순모델과 2차원 구조물에서의 결합부위 단순모델의 정확성을 평가하였다.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.89-102
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• 2021

Rapid construction of prefabricated bridges requires minimizing the field work of precast members and ensuring structural stability and constructability. In this study, we conducted experimental and analytical investigations of transverse joints of prefabricated T-girder bridge superstructures to verify the flexural performance and serviceability. In addition, we conducted parametric studies to identify the joint parameters. The results showed that both the segmented and continuous specimens satisfied the ultimate flexural strength criterion, and the segmented specimen exhibited unified behavior, with the flexural strength corresponding to that of the continuous specimen. The segmented specimens exhibited elastic behavior under service load conditions, and the maximum crack width satisfied the acceptance criteria. The reliability of the finite element model of the joint was verified, and parametric analysis of the convexity of the joint section and the compressive strength of the filler concrete showed that the minimum deflection and crack width occurred at a specific angle. As the strength of the filler concrete increased, the deflection and crack width decreased. However, we confirmed that the reduction in the crack width was hardly observed above a specific strength. Therefore, a design suitable for prefabricated bridges and accelerated construction can be achieved by improving the joint specifications based on the required criteria.

• 한국산업융합학회 논문집
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• 제25권1호
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• pp.87-99
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• 2022

We propoes a study on the dynamic characteristics analysis and position control of 5-degree multi-joint manipulators for untact remote working at construction sites and manufacturing plants. The main frame of freedom multi-joint manipulator consists of five elements, boom cylinder, boom cylinder, arm cylinder, bucket cylinder, and rotation joint and link. In addition, the main purpose of the proposed system is to realize the work of the manufacturing process or construction site by remote control. Motion control of the entire system is a servo valve control method by hydraulic servo cylinders for one to four joints, and a servo motor control method is applied for five joints. The reliability of the proposed method was verified through performance experiments by computer simulation.

• Structural Engineering and Mechanics
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• 제48권2호
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• pp.221-239
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• 2013

This paper focuses on a development of strut-and-tie model (STM) to predict the capacity of an improved longitudinal joint for decked bulb-tee bridge systems. Nine reinforced concrete beam/slab specimens anchored by spliced headed bars with different details were tested. Test results were evaluated and compared with an anticipation of the validated STM. The proposed STM provides a lower bound of the ultimate capacity of the joint zone. It shows that the lap length of headed bars has a significant effect on structural behaviors of the improved joint. To develop a full strength joint, the range of the lap length can be determined by the strength and compatibility requirement. Design recommendations to spliced headed bars, concrete strength, as well as lacer bars in the joint zone are proposed for developing a full strength joint.

• Advances in Computational Design
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• 제4권4호
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• pp.343-365
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• 2019

Among the themes related to earthquake countermeasures at construction sites, those for tower cranes are particularly important. An accident involving the collapse of a crane during the construction of a skyscraper has serious consequences, such as human injury or death, enormous repair costs, and significant delays in construction. One of the causes of deadly tower crane collapses is the destruction of the site joints of the tower crane mast. This paper proposes a new design method by static elastoplastic finite element analysis using a supercomputer for the design of the end plate-type tensile bolted joints, which are generally applied to the site joints of a tower crane mast. This new design method not only enables highly accurate and reliable joint design but also allows for a design that considers construction conditions, such as the introduction of a pre-tension axial force on the bolts. By applying this new design method, the earthquake resistance of tower cranes will undoubtedly be improved.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.131-132
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• 2020

Recently, interest in OSC(Off Site Construction) is increasing due to the trend of a decrease in skilled workers and an increase in labor costs. In this regard, PC(Precast Concrete) is being reviewed for apartments, the most common type of housing in Korea. As the biggest concern for PC apartment houses, civil complaints such as inter-floor noise and leakage were presented. In this study, the details of the joints were reviewed based on the past cases of PC apartments, and the details of the recently constructed or planned PC apartments were investigated. Through this, the leakage path in the past was analyzed through the existing research literature and data, and a discussion was conducted on the direction for a detailed proposal of an improved joint in the future.