• 제목/요약/키워드: Lifting an object

검색결과 34건 처리시간 0.022초

삼각형 패널 상에 선형적으로 분포된 다이폴 강도를 갖는 패널법의 정식화 (Formulation of the Panel Method with Linearly Distributed Dipole Strength on Triangular Panels)

  • 오진안;이진태
    • 대한조선학회논문집
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    • 제57권2호
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    • pp.114-123
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    • 2020
  • A high-order potential-based panel method based on Green's theorem, with piecewise-linear dipole strength on triangular panels, is formulated for the analysis of potential flow around a three-dimensional wing. Previous low-order panel methods adopt square panels with piecewise-constant dipole strength, which results in inherent errors. Square panels can not represent a high curvature lifting body, such as propellers, since the four vertices of the square panel do not locate at the same flat plane. Moreover the piecewise-constant dipole strength induces inevitable errors due to the steps in dipole strength between adjacent panels. In this paper a high-order panel method is formulated to improve accuracy by adopting a piecewise linear dipole strength on triangular panels. Firstly, the square panels are replaced by triangular panels in order to increase the geometric accuracy in representing the shape of the object with large curvature. Next, the step difference of the dipole strength between adjacent panels is removed by adopting piecewise-linear dipole strength on the triangular panels. The calculated results by the present method is compared with analytical ones for simple non-lifting geometries, such as ellipsoid. The results for an elliptic wing with zero thickness at finite angle of attack are compared with Jordan's results. The comparison shows reasonable agrements for the both lifting and non-lifting bodies.

에어밸런서 공압 회로의 설계 및 성능 실험 (Pneumatic circuit design and Performance test of Air balancer)

  • 김동수;배상규
    • 유공압시스템학회논문집
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    • 제3권3호
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    • pp.20-24
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    • 2006
  • Air balancer is a conveyance cargo-handling machine, used in assembly and process lines of car and machining industries. This can lift up an object, the weight of which is from 5 to 200 kg, and moves it to a position. As industrial technologies evolve, it is required to move an object and fit it into a specified position with greater accuracy, rather than performing simple tasks such as lifting objects up and down as conventional ones do. There is also a demand to handle an object with one hand, rather than with two hands,. Through designs of manifold unit for an air balancer function, pilot regulator unit to keep pressure constant, hand unit for an accurate load perception function, and air balancer circuit, this study enables everybody to work it with ease and convenience. Experiments and comparisons were conducted for the performance evaluation of the circuit.

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Experimental and numerical study on coupled motion responses of a floating crane vessel and a lifted subsea manifold in deep water

  • Nam, B.W.;Kim, N.W.;Hong, S.Y.
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제9권5호
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    • pp.552-567
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    • 2017
  • The floating crane vessel in waves gives rise to the motion of the lifted object which is connected to the hoisting wire. The dynamic tension induced by the lifted object also affects the motion responses of the floating crane vessel in return. In this study, coupled motion responses of a floating crane vessel and a lifted subsea manifold during deep-water installation operations were investigated by both experiments and numerical calculations. A series of model tests for the deep-water lifting operation were performed at Ocean Engineering Basin of KRISO. For the model test, the vessel with a crane control system and a typical subsea manifold were examined. To validate the experimental results, a frequency-domain motion analysis method is applied. The coupled motion equations of the crane vessel and the lifted object are solved in the frequency domain with an additional linear stiffness matrix due to the hoisting wire. The hydrodynamic coefficients of the lifted object, which is a significant factor to affect the coupled dynamics, are estimated based on the perforation value of the structure and the CFD results. The discussions were made on three main points. First, the motion characteristics of the lifted object as well as the crane vessel were studied by comparing the calculation results. Second, the dynamic tension of the hoisting wire were evaluated under the various wave conditions. Final discussion was made on the effect of passive heave compensator on the motion and tension responses.

미지 물체의 구속상태에 관한 실시간 추정방법 (Estimation Method for Kinematic Constraint of Unknown Object by Active Sensing)

  • 황창순
    • 대한기계학회논문집A
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    • 제29권2호
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    • pp.188-200
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    • 2005
  • Control of a multi-fingered robotic hand is usually based on the theoretical analysis for kinematics and dynamics of fingers and of object. However, the implementation of such analyses to robotic hands is difficult because of errors and uncertainties in the real situations. This article presents the control method for estimating the kinematic constraint of an unknown object by active sensing. The experimental system has a two-fingered robotic hand suspended vertically for manipulation in the vertical plane. The fingers with three degrees-of-freedom are driven by wires directly connected to voice-coil motors without reduction gears. The fingers are equipped with three-axis force sensors and with dynamic tactile sensors that detect slippage between the fingertip surfaces and the object. In order to make an accurate estimation for the kinematic constraint of the unknown object, i.e. the constraint direction and the constraint center, four kinds of the active sensing and feedback control algorithm were developed: two position-based algorithms and two force-based algorithms. Furthermore, the compound and effective algorithm was also developed by combining two algorithms. Force sensors are mainly used to adapt errors and uncertainties encountered during the constraint estimation. Several experimental results involving the motion of lifting a finger off an unknown object are presented.

타워크레인 텔레스코핑 작업의 안전리스크 대응방안 연구 (A Study on the Safety Risk of Telescoping Work of Tower Cranes)

  • 이동훈;최재휘;김선국
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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    • pp.9-13
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    • 2009
  • As recent construction projects are bigger and higher, the importance of lifting is increasing. In construction sites tower cranes are an essential lifting equipment covering were than 50% of all construction activities. But due to neglect of safety supervision, tower crane-related accidents are frequently taking place. Since most of construction activities is done in heights, the accidents are more likely to be catastrophic. According to an analysis of the causes of tower crane-related accidents, 49% of all accidents claimed for certain periods($1999{\sim}2003$) occurred in the process of telescoping work. Therefore, this research is conducted with the object of analyzing telescoping work of tower cranes and presenting solutions against safety risk. It is expected that the results of this study can be used as useful basic data or material when preparing for effective safety management for tower cranes.

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Creating Deep Learning-based Acrobatic Videos Using Imitation Videos

  • Choi, Jong In;Nam, Sang Hun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제15권2호
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    • pp.713-728
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    • 2021
  • This paper proposes an augmented reality technique to generate acrobatic scenes from hitting motion videos. After a user shoots a motion that mimics hitting an object with hands or feet, their pose is analyzed using motion tracking with deep learning to track hand or foot movement while hitting the object. Hitting position and time are then extracted to generate the object's moving trajectory using physics optimization and synchronized with the video. The proposed method can create videos for hitting objects with feet, e.g. soccer ball lifting; fists, e.g. tap ball, etc. and is suitable for augmented reality applications to include virtual objects.

Approximate calculation of the static analysis of a lifted stay cable in super-long span cable-stayed bridges

  • Zhao, Xinwei;Xiao, Rucheng;Sun, Bin
    • Structural Engineering and Mechanics
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    • 제74권5호
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    • pp.635-655
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    • 2020
  • The sag effect of long stay cables is one of the key factors restricting further increase in the span of cable-stayed bridges. Based on the formerly proposed concept of long stay cables lifted by an auxiliary suspension cable in cross-strait cable-stayed bridges, corresponding static approximate calculations and analytical theory based on catenary and parabolic cable configurations are established. Taking a main span 1400 m cable-stayed bridge as the research object, three typical lifting conditions and the whole process of auxiliary cable lifting are analyzed and discussed. The results show that the sag effect is effectively reduced. The support efficiency is only improved when the cables are lifted above the original cable chord. Reduction of the horizontal component force of the cable is limited. The equivalent elastic modulus and the vertical support stiffness of the lifted cables are significantly increased with increased horizontal projection length and not sensitive to the change of the lifting point position. The scheme of lifting the cable to the chord midpoint is more economical because of the less steel required for the auxiliary suspension cable, but its effect on improving the vertical support efficiency is limited. The support efficiency is better when the cable is lifted to the cable end tangential to the original cable chord, but the lifting force and the cross-sectional area of the auxiliary suspension cable are doubled. The approximate calculation results of the lifted cables are very close to the numerical analysis results, which verifies the applicability of the approximation method proposed in this study. The results of parabolic approximation calculations are approximately equal to that of catenary cable geometry. As the parabolic approximation analysis theory of lifted cables is more convenient in mathematical processing, it is feasible to use parabolic approximation analysis theory as the analytical method for the conceptual design of lifted cables of super-long span cable-stayed bridges.

컨테이너 터미널의 ALV 시스템을 위한 시뮬레이션 모형 (A Simulation Model for an ALV System at a Container Terminal)

  • 배종욱;최상희;김창현;박순오
    • 한국시뮬레이션학회논문지
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    • 제17권4호
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    • pp.29-39
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    • 2008
  • 최근 본선작업의 대기시간을 단축할 수 있는 효율적인 이송장비로 ALV(Automated Lifting Vehicle)가 연구되고 있다. 그러나 ALV와 다른 하역장비의 연계에 대한 구체적인 분석을 수행한 후 동적 요소들을 반영한 연구는 미흡하다. ALV의 수행도는 동적 환경하의 자가하역 작업, 차량간 방해, 가용한 작업 공간의 점유에 크게 좌우된다. 그러므로 ALV 시스템이 도입된 컨테이너 터미널의 생산성을 평가하는 것은 매우 어렵다. 따라서ALV시스템에 적합한 운영 규칙을 갖춘 시뮬레이션 모형으로 개발되어야 한다. 또한 모형은 연계작업과 차량 주행의 특성을 고려해야 한다. 본 연구는 수평형 컨테이너 터미널을 가정하고 하역작업 과정을 분석하고 시뮬레이션 모형에 필요한 주요 운영 규칙을 제시하였다. 그리고 객체지향 시뮬레이션 소프트웨어인 Anylogic을 이용하여 ALV 시스템에 기반한 컨테이너 터미널 시뮬레이션 모형을 개발하였다.

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대평판 이송을 위한 비접촉 헤드 설계 (Design of Non-Contact Pick-Up Head for Carrying Large Flat Sheets)

  • 김준현;김영글;안성욱;김용성
    • 한국생산제조학회지
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    • 제22권6호
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    • pp.937-944
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    • 2013
  • This paper describes an improved model that can be used for configuring a non-contact pneumatic head to handle a large sheet of glass. The cylindrical head model is of a large size (70 mm). It operates on vortex flow, which can simultaneously generate suction and repulsion over the flat object's surface. The head allows for the minimal non-contact lifting of objects weighing over 3N by using reference conditions (working pressure and head dimensions). Additionally, a functional flow-guide is applied for inducing a developing tangential vortex flow to increase suction and repulsion to the reference head. The cylindrical flow-guide is associated with relatively low tangential velocity. The improved model generates greater lifting force than the reference model, as verified experimentally.

고압 피스톤 펌프용 슬리퍼 베어링의 변형 특성에 관한 연구 (A Study on the Deformation Characteristics of a Slipper Bearing for High Pressure Piston Pump)

  • 고성위;김병탁
    • 한국해양공학회지
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    • 제23권5호
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    • pp.39-44
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    • 2009
  • The hydrostatic slipper bearing is generally used in high pressure axial piston pumps to support the load generated from two surfaces which are sliding relatively at low speed. The object of the bearing is to remove the possibility of direct contact by maintenance of an adequate oil film thickness between two metal surfaces. Because the bearing performance is influenced by the bearing deformation, it is highly dependent on the injection pressure, the bearing surface profile and so on. In this study, the deformation characteristics of a hydrostatic slipper bearing is investigated according to the injection pressure by the finite element analysis. In the analysis, the special boundary condition to take the fluid-structure interaction (FSI) into account is used on the interactive surface. The results, such as bearing deformation, stress and lifting force, obtained from the fully coupled analysis are compared with those from the single step sequential method.