• Title/Summary/Keyword: Free-surface motion

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Joint Mobilization Techniques of the Shoulder Joint Dysfunction (견관절 장애와 관절 가동운동(mobilization))

  • Kim, Suhn-Yeop
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.2 no.1
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    • pp.39-49
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    • 1996
  • The techniques of joint mobilization and traction are used to improve joint mobility or to decrease pain by restoring accessory movements to the shoulder joints and thus allowing full, nonrestriced, pain-free range of motion. In the glenohumeral joint, the humeral head would be the convex surface, while the glenoid fossa would be the concave surface. The medial end of the clavicle is concave anterioposteriorly and convex superioinferiorly, the articular surface of the sternum is reciprocally curved. The acromioclavicular joint is a plane synovial joint between a small convex facet on lateral end of the clavicle and a small concave facet on the acromion of the scapula. The relationship between the shape of articulating joint surface and the direction of gliding is defined by the convex-concave rule. If the concave joint surface is moving on a stationary convex surface, gliding occur in the same direction as the rolling motion. If the convex surface is moving on a stationary concave surface, gliding will occur in an opposite direction to rolling. Hypomobile shoulder joint are treated be using a gliding technique.

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IMPROVEMENT OF MPS METHOD IN SIMULATING VIOLENT FREE-SURFACE MOTION AND PREDICTING IMPACT-LOADS (유체 충격 하중 예측을 위한 MPS법의 개량)

  • Hwang, S.C.;Lee, B.H.;Park, J.C.
    • Journal of computational fluids engineering
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    • v.15 no.1
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    • pp.71-80
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    • 2010
  • The violent free-surface motions and the corresponding impact loads are numerically simulated by using the Moving Particle Semi-implicit (MPS) method, which was originally proposed by Koshizuka and Oka (1996) for incompressible flows. In the original MPS method, there were several shortcoming including non-optimal source term, gradient and collision models, and search of free-surface particles, which led to less-accurate fluid motions and non-physical pressure fluctuations. In the present study, how those defects can be remedied is illustrated by step-by-step improvements in respective processes of the revised MPS method. The improvement of each step is explained and numerically demonstrated. The numerical results are also compared with the experimental results of Martin and Moyce (1952) for dam-breaking problem. The current numerical results for violent free-surface motions and impact pressures are in good agreement with their experimental data.

Vibration analysis of inhomogeneous nonlocal beams via a modified couple stress theory incorporating surface effects

  • Ebrahimi, Farzad;Safarpour, Hamed
    • Wind and Structures
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    • v.27 no.6
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    • pp.431-438
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    • 2018
  • This paper presents a free vibration analysis of size-dependent functionally graded (FG) nanobeams with all surface effects considerations on the basis of modified couple stress theory. The material properties of FG nanobeam are assumed to vary according to power law distribution. Based on the Euler-Bernoulli beam theory, the modeled nanobeam and its equations of motion are derived using Hamilton's principle. An analytical method is used to discretize the model and the equation of motion. The model is validated by comparing the benchmark results with the obtained results. Results show that the vibration behavior of a nanobeam is significantly influenced by surface density, surface tension and surface elasticity. Also, it is shown that by increasing the beam size, influence of surface effect reduces to zero, and the natural frequency tends to its classical value.

Study on Roll Motion Characteristics of a Rectangular Floating Structure in Regular Waves (규칙파 중 사각형 부유식 구조물의 횡동요 운동특성에 대한 연구)

  • Kim, Min-Gyu;Jung, Kwang-Hyo;Park, Sung-Boo;Lee, Gang-Nam;Park, Il-Ryong;Suh, Sung-Bu
    • Journal of Ocean Engineering and Technology
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    • v.33 no.2
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    • pp.131-138
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    • 2019
  • This study focused on the roll motion characteristics of a two-dimensional (2D) rectangular floating structure under regular beam sea conditions. An experiment was conducted in a 2D wave tank for a roll free decay test in calm water and the roll motion in a range of regular waves with and without heave motion to investigate the motion response and heave influence on the roll motion. A numerical study was carried out using Reynolds-averaged Navier Stokes (RANS)-based CFD simulations. A grid convergence test was conducted to accurately capture the wave condition on the free surface based on the overset mesh and wave forcing method. It was found in the roll free decay test that the numerical results agreed well with the experimental results for the natural roll period and roll damping coefficient. It was also observed that the heave motion had an impact on the roll motion, and the responses of the heave and roll motion from the CFD simulations were in reasonable agreement with those from the experiment.

A Study on Application of PIV to Sloshing Phenomenon inside Rectangular Tank (장방형탱크 내부 슬로싱 현상에 관한 PIV적용에 관한 연구)

  • Kim, K.S.;Choi, J.Y.;Cho, D.H.
    • Proceedings of KOSOMES biannual meeting
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    • 2009.06a
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    • pp.85-86
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    • 2009
  • The sloshing phenomenon can be defined as the nonlinear movement of the free-surface of liquids inside tanks. It generates dynamic loads on the tank structure and thus becomes a problem of relative importance in the design of marine structures. The present study describes a experiment of the sloshing of flows with free-surface which contained in a rectangular tank moving in pitching motion.

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Training-Free sEMG Pattern Recognition Algorithm: A Case Study of A Patient with Partial-Hand Amputation (무학습 근전도 패턴 인식 알고리즘: 부분 수부 절단 환자 사례 연구)

  • Park, Seongsik;Lee, Hyun-Joo;Chung, Wan Kyun;Kim, Keehoon
    • The Journal of Korea Robotics Society
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    • v.14 no.3
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    • pp.211-220
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    • 2019
  • Surface electromyogram (sEMG), which is a bio-electrical signal originated from action potentials of nerves and muscle fibers activated by motor neurons, has been widely used for recognizing motion intention of robotic prosthesis for amputees because it enables a device to be operated intuitively by users without any artificial and additional work. In this paper, we propose a training-free unsupervised sEMG pattern recognition algorithm. It is useful for the gesture recognition for the amputees from whom we cannot achieve motion labels for the previous supervised pattern recognition algorithms. Using the proposed algorithm, we can classify the sEMG signals for gesture recognition and the calculated threshold probability value can be used as a sensitivity parameter for pattern registration. The proposed algorithm was verified by a case study of a patient with partial-hand amputation.

A Study of Site-Specific Design ground Motions in Earthquake-Resistant Design for Geotechnical Structures (지반구조물 내진설계시 부지특성을 고려한 설계 지반운동연구)

  • 권수영;박인준
    • Journal of the Earthquake Engineering Society of Korea
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    • v.4 no.2
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    • pp.37-46
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    • 2000
  • 본 논문에서는 부지특성을 고려한 설계지반운동의 산정방법을 연구하였으며 그 해석결과를 지반 구조물의 내진설계에 적용하는 방법을 제안하였다 지진응답 해석시 사용되는 설계응답스펙트럼과 설계시간 이력등의 입력운동의 통제점 위치가 지반구조물 내진설동 지층내 암반운동 그리고 노두운동을 사용하는 방법으로 나눌 수 있고 이에 따라 작용 설계지진운동이 변화하므로 지반구조물의 경계조건에 적합한 방법을 사용하여야 한다.

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A Study on the Deformation control of Free Surface of Magnetic Fluid (자성유체 자유표면의 형상 제어에 관한 연구)

  • 안창호;김대영;지병걸;이은준;박명관
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.297-300
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    • 2002
  • In this study, the deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. While applied magnetic fields are induced by 4$\times$4 electromagnet located under the magnetic fluid, the surface of the magnetic fluid is formed the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body farce. In case, magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. thus, the device of a magnetic fluid proposed the surface actuator. The device of surface deformation as well comparison between numerical simulation and experiments as will be presented.

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Motion Analysis of an Underwater Vehicle Running near Wave Surface (파랑수면 근처에서 항주하는 수중운동체의 운동해석)

  • Yoon, Hyeon Kyu;Ann, Seong Phil;Jung, Chulmin;Kim, Chan-Ki
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.3
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    • pp.395-403
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    • 2016
  • A cylinder-type underwater vehicle for military use that is running near the free surface at the final homing stage to hit a surface ship target is affected by wave force and moment. Since wave can affect an underwater vehicle running at the depth less than half of the modal wave length, it is important to confirm that the underwater vehicle can work well in such a situation. In this paper, wave force and moment per unit wave amplitude depending on wave frequency, wave direction, and vehicle's running depth were calculated by 3-Dimensional panel method, and the numerical results were modeled in external force terms of six degrees of freedom equations of motion. Motion simulation of the underwater vehicle running in various speed, depth, and sea state were performed.

A Study on the Surface Control of a Magnetic Fluid (자성유체의 표면제어에 관한 연구)

  • Shin, J.O.;Rhee, E.J.;Park, M.K.
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.65-69
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    • 2001
  • In this study, the deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed. In case, magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage Sealing and the surface actuator. The device of surface deformation as well comparison between numerical simulation and experiments as will be presented.

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