• Title/Summary/Keyword: Lift-up

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Slip Detection of Robot Gripper with Flexible Tactile Sensor (유연 촉각 센서를 이용한 로봇 그리퍼의 미끄러짐 감지)

  • Seo, Ji Won;Lee, Ju Kyoung;Lee, Suk;Lee, Kyung Chang
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.2
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    • pp.157-164
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    • 2014
  • In this paper, we design a gripping force control system using tactile sensor to prevent slip when gripper tries to grasp and lift an object. We use a flexible tactile sensor for measuring uniplanar pressure on gripper's finger and develop an algorithm to detect the onset of slip using the sensor output. We also use a flexible pressure sensor to measure the normal force. In addition, various signal processing techniques are used to reduce noise included in the sensor output. A 3-finger gripper is used to grasp and lift up a cylindrical object. The tactile sensor is attached on one of fingers, and sends output signals to detect slip. Whenever the sensor signal is similar to the slip pattern, gripper force is increased. In conclusion, this research shows that slip can be detected using the tactile sensor and we can control gripping force to eliminate slip between gripper and object.

ANALYSIS OF UNSTEADY OSCILLATING FLOW AROUND TWO DIMENSIONAL AIRFOIL AT HIGH ANGLE OF ATTACK (고받음각 2차원 에어포일 주위의 비정상 유동의 진동 특성에 관한 연구)

  • Yoo, J.K.;Kim, J.S.
    • Journal of computational fluids engineering
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    • v.18 no.1
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    • pp.1-6
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    • 2013
  • Missile and fighter aircraft have been challenged by low restoring nose-down pitching moment at high angle of attach. The consequence of weak nose-down pitching moment can be resulting in a deep stall condition. Especially, the pressure oscillation has a huge effect on noise generation, structure damage, aerodynamic performance and safety, because the flow has strong unsteadiness at high angle of attack. In this paper, the unsteady aerodynamics coefficients were analyzed at high angle of attack up to 50 degrees around two dimensional NACA0012 airfoil. The two dimensional unsteady compressible Navier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-Order Compact) scheme. The flow conditions are Mach number of 0.3 and Reynolds number of $10^5$. The lift, drag, pressure, entropy distribution, etc. are analyzed according to the angle of attack. The results of average lift coefficients are compared with other results according to the angle of attack. From a certain high angle of attack, the strong vortex formed by the leading edge are flowing downstream as like Karman vortex around a circular cylinder. The primary and secondary oscillating frequencies are analyzed by the effects of these unsteady aerodynamic characteristics.

Improving the Self-starting Performance of a VAWT (수직축 풍차의 자기동 성능 개선)

  • Cheong, Seon-Hwan;Choi, Seong-Dae;Shon, Jae-Yul;Mag-isa, Alexander;Kim, Shin-Ho;Choi, Myoung-Su
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.4
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    • pp.13-20
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    • 2006
  • The inherent problem of a Darrieus wind turbine is its inability to self-start. Usually, a motor is used to provide angular acceleration until lift forces are produced in the airfoil blades or up until the turbine can already sustain its speed on its own. This paper describes a method of improving the self-starting of an H-type Darrieus vertical axis wind turbine (VAWT) by incorporating a helical Savonius turbine thus utilizing a drag-lift combination. The effect of each turbine in the combination relative to each other is investigated by testing a prototype windmill consisting of three NACA 0015 airfoil blades combined with a Savonius rotor with a helix angle of 180 degrees and whose swept area equals 30% of the entire turbine.

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The Development and Application of Sound Quality Index for the Improving Sound Quality to Road Vehicle Power Window System (차량 윈도우 리프트 음질 향상을 위한 음질 지수 제작 및 개선에의 응용)

  • Kim, Seong-Hyeon;Park, Dong-Chul;Jo, Hyeon-Ho;Seong, Won-Chan;Kang, Yeon-June
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.525-530
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    • 2013
  • With the increasing the importance of emotional quality of vehicle, the sound quality of systems with electric motor components has become increasingly important. Electric motors are used for windows, seats, sun roof, mirrors, steering columns, windshield wiper, climate control blowers, etc. In this paper, a study was conducted to identify sound quality factors that contribute to customer's satisfaction and preference of the window lift system. Jury test for subjective evaluation was carried out and sound quality index was developed. Averaged sound pressure level and sharpness were significant factors when glass moves down. Also, maximum loudness at stop section and averaged loudness were significant factor when glass moves up. Noise source identification was carried out for the reduced the loudness and sharpness during glass transferred section and impulsive noise at stop section, Using the source identification result, several improvement points were applied. And finally, the degree of sound quality improvement was judged using sound quality index.

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Bidirectional DC-DC Converter Based on Quasi-Sepic for Battery Charging System

  • Zhang, Hailong;Chen, Yafei;Kim, Dong-Hee;Park, Sung-Jun;Park, Seong-Mi
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.2_1
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    • pp.139-147
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    • 2020
  • In order to satisfy the voltage levels of the low voltage battery side and high voltage DC bus, a high voltage gain with bidirectional operation is required. In this system, the cost effectiveness of the design is a critical factor; therefore, the system should be designed using a small number of components. This paper propose a novel bidirectional converter composed with a quasi-sepic and switched-indictor network. The proposed converter consists a small number of components with a high voltage gain ratio. Detailed analysis are made with respect to the operating mode, number of components, voltage and current ripple and efficiency. To verify performance of the proposed converter, simulation was performed is this paper. The simulation results are shown to verify the feasibility and performance of the proposed bidirectional converter.

Measured aerodynamic coefficients of without and with spiked blunt body at Mach 6

  • Kalimuthu, R.;Mehta, R.C.;Rathakrishnan, E.
    • Advances in aircraft and spacecraft science
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    • v.6 no.3
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    • pp.225-238
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    • 2019
  • A spike attached to a blunt nosed body significantly alters its flow field and influences the aerodynamic coefficients at hypersonic speed. The basic body is an axisymmetric, with a hemisphere nose followed by a cylindrical portion. Five different types of spikes, namely, conical aerospike, hemisphere aerospike, flat-face aerospike, hemisphere aerodisk and flat-face aerodisk are attached to the basic body in order to assess the aerodynamic characteristic. The spiked blunt body without the aerospike or aerodisk has been set to be a basic model. The coefficients of drag, lift and pitching moment were measured with and without blunt spike body for the length-to-diameter ratio (L/D) of 0.5, 1.0, 1.5 and 2.0, at Mach 6 and angle of attack up to 8 degrees using a strain gauge balance. The measured forces and moment data are employed to determine the relative performance of the aerodynamic with respect to the basic model. A maximum of 77 percent drag reduction was achieved with hemisphere aerospike of L/D = 2.0. The comparison of aerodynamic coefficients between the basic model and the spiked blunt body reveals that the aerodynamic drag and pitching moment coefficients decrease with increasing the L/D ratio and angle of attack but the lift coefficient has increasing characteristics.

Analysis of dynamic behavior of Railroad Steel Bridges According to Bridge Bearing Types (교량받침 형식에 따른 판형교 동적 분석)

  • Choi, Eun-Soo;Choi, Seung-Hwan
    • Journal of the Korean Society for Railway
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    • v.15 no.1
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    • pp.62-70
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    • 2012
  • Dynamic behaviors of line type bearings, spherical bearings and disk bearings which are being used for railway steel bridges are investigated, and that of the bridges is also analyzed. For the purpose, the vertical displacements of the three bearings including fixed and expansion type are measured and analyzed. Also, the deformation of the PTFE plate placed inside of spherical and disk bearings of expansion type is measured and its effect on the dynamic behavior of the bridges is discussed. The up-lift phenomenon at the bearings installed for the steel bridges is estimated. The vertical displacements at mid-span of the bridges are compared according to the bearing types. Finally, the 1st mode natural frequencies are estimated and the relationship to the vertical displacement is discussed.

A Study on the Performance of Surface UV Printing Device for Power Indicator Production (파워인덕터 생산용 표면 UV 인쇄장치 성능 연구)

  • Hyun-Mu Lee;So-Mi An;Sung-Min Ahn;Jeong-Hwan Seo;Byoung-Jo Jung;Sung-Lin Kang
    • Journal of Advanced Technology Convergence
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    • v.2 no.4
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    • pp.1-6
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    • 2023
  • Research on power inductor surface UV printing equipment using cylindrical magnets can prevent damage to quality consumable materials (making plates, Squeegees) during printing and improve printing quality by applying technology to prevent product from flipping or standing up when fixing the product by making the magnetic formation of cylindrical magnets form up and down. The development of cylindrical magnets that changed the direction of magnetic force will stabilize the fixing method for metal products made by powder compression, increasing the production capacity for small products. Finally, by studying the power inductor surface UV printing device using cylindrical magnets, it can be differentiated from the spray and deeping methods that were being worked on, production will be greatly improved, and as a result, cost reduction and competitive production will be possible.

Innovative Methodology for Assembling Jack up Leg of 205m on ground of Ultra

  • Yang, Yeong-Tae;Sim, Song-Seop;Lee, Seung-Yeop;Hwang, Oe-Ju;Sin, Bong-Yeong
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.87-92
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    • 2003
  • Generally, in jack up rig design for harsh environment, its leg height is a major factor for achieving a sufficient serviceability & operability in terms of the worst environment and the workable depth. Due to difficulties in constructing such a high-slender leg, inaccessibility of yard fabrication equipment, etc. the construction of Jack up rig fur harsh deep sea has not been common. Method using heavy crawler crane, fabrication tower or extension by the floating crane vessel is still conventional construction but, considering high cost fur mobilizing heavy lift vessel (HLV) or additional marine work for implementing preload / full height test at sea, the ground-base construction is much advantageous. Air skidding method (ASM hereafter) is ground-based construction methodology, newly developed due to such requests. ASM could also be extended to similar engineering fields. This paper presents the operating sequence, design parameters and procedure which were verified through successful operation at the end of May 2002.

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

  • Kim, D.S.;Bae, S.K.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.3
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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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