• Title/Summary/Keyword: A-frame method

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A Study on a Visual Sensor System for Weld Seam Tracking in Robotic GMA Welding (GMA 용접로봇용 용접선 시각 추적 시스템에 관한 연구)

  • 김동호;김재웅
    • Journal of Welding and Joining
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    • v.19 no.2
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    • pp.208-214
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    • 2001
  • In this study, we constructed a visual sensor system for weld seam tracking in real time in GMA welding. A sensor part consists of a CCD camera, a band-pass filter, a diode laser system with a cylindrical lens, and a vision board for inter frame process. We used a commercialized robot system which includes a GMA welding machine. To extract the weld seam we used a inter frame process in vision board from that we could remove the noise due to the spatters and fume in the image. Since the image was very reasonable by using the inter frame p개cess, we could use the simplest way to extract the weld seam from the image, such as first differential and central difference method. Also we used a moving average method to the successive position data or weld seam for reducing the data fluctuation. In experiment the developed robot system with visual sensor could be able to track a most popular weld seam. such as a fillet-joint, a V-groove, and a lap-joint of which weld seam include planar and height directional variation.

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Economic Analysis of Connection and Anchorage Methods of Bottom Rebar for Composite Precast Concrete Girder (합성 PC 보의 하부철근 이음 및 정착방법에 따른 경제성 검토)

  • Cho, Wonhyun;Lim, Chaeyeon;Kim, Sunkuk
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.05a
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    • pp.11-12
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    • 2015
  • Green Frame is a Rahmen structure made of composite precast concrete members. According to the concrete design code, a lower rebar of precast concrete girder, should be extended to the inner precast concrete column. However, such extension of lower rebar may sharply reduce its constructability. To satisfy the criteria, the connection and anchorage of beam rebar should be taken into consideration, yet it is difficult to use lapping as it is not easy to ensure enough space when Green Frame method is adopted. To solve this, a new method of lower rebar connection and anchorage was developed, and this study is intended to review economic feasibility prior to applying the method developed onto sites. The study result can be used as basic data for selection of the optimal joint and anchorage method for lower rebar of the green frame construction.

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Free vibration and harmonic response of cracked frames using a single variable shear deformation theory

  • Bozyigit, Baran;Yesilce, Yusuf;Wahab, Magd Abdel
    • Structural Engineering and Mechanics
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    • v.74 no.1
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    • pp.33-54
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    • 2020
  • The aim of this study is to calculate natural frequencies and harmonic responses of cracked frames with general boundary conditions by using transfer matrix method (TMM). The TMM is a straightforward technique to obtain harmonic responses and natural frequencies of frame structures as the method is based on constructing a relationship between state vectors of two ends of structure by a chain multiplication procedure. A single variable shear deformation theory (SVSDT) is applied, as well as, Timoshenko beam theory (TBT) and Euler-Bernoulli beam theory (EBT) for comparison purposes. Firstly, free vibration analysis of intact and cracked frames are performed for different crack ratios using TMM. The crack is modelled by means of a linear rotational spring that divides frame members into segments. The results are verified by experimental data and finite element method (FEM) solutions. The harmonic response curves that represent resonant and anti-resonant frequencies directly are plotted for various crack lengths. It is seen that the TMM can be used effectively for harmonic response analysis of cracked frames as well as natural frequencies calculation. The results imply that the SVSDT is an efficient alternative for investigation of cracked frame vibrations especially with thick frame members. Moreover, EBT results can easily be obtained by ignoring shear deformation related terms from governing equation of motion of SVSDT.

A Case Study on Explosive Demolition of Boiler Building of Steel Frame Structure (보일러동 철골구조물 발파해체 시공사례)

  • Park, Hoon;Nam, Sung-Woo;Noh, You-Song;Suk, Chul-Gi
    • Explosives and Blasting
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    • v.40 no.3
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    • pp.66-76
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    • 2022
  • Recently, the demand for the dismantling of old industrial complexes has been increasing, and the construction of restoring the dismantled industries to their original natural environment is underway. In this case, the felling method was applied to the explosive demolition method to dismantle a large steel frame structure in an old industrial complex. We used a charging container to cut the steel frame structure that generates a metal jet. The thickness of the thick steel structure in the blasting section was controlled by gouging which a method of digging deep groove by gas and oxygen flame or arc thermal. As a result of the explosive demolition, the steel frame structure collapsed precisely according to the estimated direction. The explosive demolition was completed without causing any damage to the surrounding facilities.

Structural Optimal Design of the Frame of a Desktop Servo Pressing Machine (탁상용 압입기 프레임의 구조최적설계)

  • Lee, Boo-Youn;Jung, Jin-Uk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.7
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    • pp.3142-3150
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    • 2013
  • Present research deals with an optimal design of the C-type frame of a desktop pressing machine to minimize its deformation which plays an important role in accuracy of the machine. Deformation pattern of the frame is analyzed by the finite element method. Design parameters are defined for the frame to derive an optimal design. Displacement and weight sensitivities of the parameters are analyzed using the method of the parametric study. On the basis of the response curves for the parameters, optimal designs of the frame are proposed. Effectiveness of the optimal design is verified by analyses in the viewpoint of the deformation and weight of the frame. Deformation of the optimized frame without increase of the weight is 87.5 % of the original frame.

On determining seismic anchor force of anchoring frame structure supporting three-stage slope

  • Lin, Yu-liang;Lu, Li;Li, Ying-xin;Xue, Yuan;Feng, Zhi-jun;Wang, Zhi-meng;Yang, Guo-lin
    • Geomechanics and Engineering
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    • v.22 no.3
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    • pp.265-275
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    • 2020
  • As a flexible supporting structure, the anchoring frame structure is widely adopted to support multistage slopes in high earthquake-intensity area for its effectiveness and practicality. The previous study indicates that the anchor of anchoring frame structure is the most likely to be damaged during earthquakes. It is crucial to determine the pull-out capacity of anchor against seismic force for the seismic design of anchoring frame structure. In this study, an analytical model of a three-stage slope supported by anchoring frame structure is established, and the upper bound method of limit analysis is applied to deduce the seismic anchor force of anchoring frame structure. The pull-out capacity of anchor against seismic force of anchoring frame structure at each stage is obtained by computer programming. The proposed method is proved to be reasonable and effective compared with the existing published solution. Besides, the influence of main parameters on the pull-out capacity of anchor against seismic force is analyzed to provide some recommendations for the seismic design of anchoring frame structure.

An Improved Joint Detection of Frame, Integer Frequency Offset, and Spectral Inversion for Digital Radio Mondiale Plus

  • Kim, Seong-Jun;Park, Kyung-Won;Lee, Kyung-Taek;Choi, Hyung-Jin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.2
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    • pp.601-617
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    • 2014
  • In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

Experimental and numerical investigation of RC frames strengthened with a hybrid seismic retrofit system

  • Luat, Nguyen-Vu;Lee, Hongseok;Shin, Jiuk;Park, Ji-Hun;Ahn, Tae-Sang;Lee, Kihak
    • Steel and Composite Structures
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    • v.45 no.4
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    • pp.563-577
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    • 2022
  • This paper presents experimental and numerical investigations of a new seismic enhancement method for existing reinforced concrete (RC) frames by using an external sub-structure, the hybrid seismic retrofit method (HSRM) system. This retrofit system is an H-shaped frame bolt-connected to an existing RC frame with an infilled-concrete layer between their gaps. Two RC frames were built, one with and one without HSRM, and tested under cyclic loading. The experimental findings showed that the retrofitted RC frame was superior to the non-retrofitted specimen in terms of initial stiffness, peak load, and energy dissipation capacity. A numerical simulation using a commercial program was employed for verification with the experiments. The results obtained from the simulations were consistent with those from the experiments, indicating the finite element (FE) models can simulate the seismic behaviors of bare RC frame and retrofitted RC frame using HSRM.

An Improved Method of Guaranteeing Frame Rates of Avionics Simulator based on HMD Motion

  • Lee, Jeong-Hoon;Jo, Yong-Il;Kim, Kyong Hoon
    • Journal of the Korea Society of Computer and Information
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    • v.23 no.7
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    • pp.57-62
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    • 2018
  • In this paper, we propose an improved algorithm for rendering method to guarantee frame rates based on HMD (Head Mounted Display) motion in an avionics simulator. One of important issues in HMD simulators is to guarantee frame rates despite fast motion of HMD which is more rapid than the aircraft's moving speed to maintain a quality of images. Therefore, we propose an algorithm considering the moving speed of a pilot's head: Improved Speed-Based LOD (Level-Of-Detail) Control (ISBLC). In the proposed algorithm, frame rates are improved by changing dynamic LOD which determines details of objects for rendering images. Throughout the experiments, we show the average frame rates are achieved up to 60 and minimum frame rates are guaranteed up to 40. The proposed algorithms will be used HMD simulation in avionics simulators.

Investigation of nonlinear behaviour of reinforced concrete frames having different stiffening members

  • Gursoy, Senol
    • Computers and Concrete
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    • v.13 no.5
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    • pp.679-694
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    • 2014
  • The selected carrier systems of reinforced concrete frame buildings are quite important on structural damages. In this study are examined comparatively nonlinear behaviours of reinforced concrete frames which having different stiffening members under a horizontal load. In that respect, the study consists of six parametric models. With this purpose, nonlinear structural analyses of reinforced concrete frames which having different stiffening members were carried out with LUSAS which uses the finite element method. Thus, some conclusions and recommendations to mitigate the damage of reinforced concrete buildings in the future designs are aimed to present. The obtained results revealed that in terms of performance, the x-shaped diagonal elements can be used as an option to shear walls. In addition, it was found that frame-2, frame-3 and frame-4 showed a better performance than traditional frame system (frame-1).