• 한국정밀공학회지
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• 제20권4호
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• pp.151-157
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• 2003

A new type of precision actuator is developed using piezoelectric bimorphs. This type of actuator is applicable for the flat surface or in-pipe system and can make forward and backward motion. Two bimorphs are linked serially and two different phased voltages are applied to each bimorph. Therefore, The end of the bimorph makes ellipsoidal motion. The device moves by the friction force between the rubber attached at the bimorph end and the inner surface of the pipe. As the results, the driving range of the device is about 0~18Hz and the device guarantees very high linearity at low frequency, 0~1 Hz. The maximum velocity of the device is about 6mm/s at 10Hz. The developed mechanism is very simple and use piezoelectric bimorph. So, it is possible to miniaturize and educe the power consumption.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.869-872
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• 2001

A new in-pipe locomotive mechanism is developed using piezoelectric bimorphs. Two bimorphs are linked serially and produce an ellipsoidal motion at the end of bimorph. The device moves by the friction force between the rubber attached at the bimorph end and the inner surface of the pipe. The developed mechanism is very simple and need relatively small power compared to a conventional multi-layer piezoelectric motor.

• 한국멀티미디어학회논문지
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• 제6권3호
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• pp.444-454
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• 2003

심장 운동의 분석은 인체에 혈액을 공급하는 역할에 대한 평가이다. 심근의 움직임을 평가하기 위해서 본 논문에서는 좌심실 심근 모델을 수학적으로 구축하였으며, 심장의 움직임에 대한 파라미터를 이용하여 운동성을 상세화 하였다. 구축한 모델을 심장의 생화학적 반응을 보이는 게이트 심근 SPECT 영상에 적용시켜서, 모델과 게이트 심근 SPECT 영상 사이의 운동성을 분석하였다. 심근 모델은 sinusoidal 함수를 이용한 3차원 super-ellipsoidal 모델을 기반으로 생성하였으며 움직임과 형태의 변화를 주기 위한 파라미터 함수를 이용하여 좌심실 심근의 형태와 움직임에 대한 유사성을 모델화 하였다. 이 모델과 심근 게이트 SPECT 영상 데이터와 LSF 알고리즘을 이용하여 fitting 시킨 후 생성된 모델을 토대로 하여 심근 게이트 SPECT 영상의 영역별 운동성 방향과 크기를 산출하여 분석하였으며, 지역적 운동성의 표현을 위해 심장기능 평가에 사용되는 Bull's Eye형식의 map을 만들었다. SPECT를 이용한 심장의 기능평가로 움직임과 수축능, 혈류 등을 이용해서 하고 있으나 운동량에 대한 평가는 없다. 본 논문에서 제안한 모델을 이용한 심근 SPECT의 운동성 분석은 심장 기능 평가에 유용한 지표가 될 것으로 기대한다.

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.209-220
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• 1998

The stability problem of steady motion of a rigid body with multi-elastic appendages and multi-liquid-filled cavities, in the presence of no external forces or torque, is considered in this paper. The flexible appendages are modeled as the clamped -free-free-free rectangular plates, or/and as the discrete mass- spring sub-system. The motion of liquid in every single ellipsoidal cavity is modeled as the uniform vortex motion with a finite number of degrees of freedom. Assuming that stationary holonomic constraints imposed on the body allow its rotation about a spatially fixed axis, the equation of motion for such a systematic configuration can be very complex. It consists of a set of ordinary differential equations for the motion of the rigid body, the uniform rotation of the contained liquids, the motion of discrete elastic parts, and a set of partial differential equations for the elastic appendages supplemented by appropriate initial and boundary conditions. In addition, for such a hybrid system, under suitable assumptions, their equations of motion have four types of first integrals, i.e., energy and area, Helmholtz' constancy of liquid - vortexes, and the constant of the Poisson equation of motion. Chetaev's effective method for constructing Liapunov functions in the form of a set of first integrals of the equations of the perturbed motion is employed to investigate the sufficient stability conditions of steady motions of the complete system in the sense of Liapunov, i.e., with respect to the variables determining the motion of the solid body and to some quantities which define integrally the motion of flexible appendages. These sufficient conditions take into account the vortexes of the contained liquids, the vibration of the flexible components, and coupling among the liquid-elasticity solid.

• 대한의용생체공학회:의공학회지
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• 제31권6호
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• pp.487-493
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• 2010

In this study, the circular friction massage technique was performed on the trapezius, the levator scapulae, and the deltoid muscles to collect the information on massage pressures and positions, and thus to utilize it in professional massage system design. Massage motion was measured with the 3-D motion capture system and finger pressures were simultaneously obtained with grip sensors. Massage motions, pressure patterns, and pressure times were different on each muscle, and the motion trajectory was similar to the ellipsoidal shape. The trapezius had higher pressure, longer massage time, and larger impulse than other muscles. These results could be useful to design a massage system based on biomechanical analysis. In order to improve massage effect, it is also strongly recommended that the tip of the system be similar with that of a human thumb in shape and material.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2483-2503
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• 2016

Traffic congestion is a severe problem in many modern cities around the world. Real-time and accurate traffic congestion identification can provide the advanced traffic management systems with a reliable basis to take measurements. The most used data sources for traffic congestion are loop detector, GPS data, and video surveillance. Video based traffic monitoring systems have gained much attention due to their enormous advantages, such as low cost, flexibility to redesign the system and providing a rich information source for human understanding. In general, most existing video based systems for monitoring road traffic rely on stationary cameras and multiple vehicle tracking method. However, most commonly used multiple vehicle tracking methods are lack of effective track initiation schemes. Based on the motion of the vehicle usually obeys constant velocity model, a novel vehicle recognition method is proposed. The state of recognized vehicle is sent to the GM-PHD filter as birth target. In this way, we relieve the insensitive of GM-PHD filter for new entering vehicle. Combining with the advanced vehicle detection and data association techniques, this multiple vehicle tracking method is used to identify traffic congestion. It can be implemented in real-time with high accuracy and robustness. The advantages of our proposed method are validated on four real traffic data.

• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.241-257
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• 2014

The modern development in design of airships and aerostats has led to unconventional configurations quite different from the classical ellipsoidal and spherical ones. This new class of air-vehicles presents a mass-to-volume ratio that can be considered very similar to the density of the fluid displaced by the vehicle itself, and as a consequence, modeling and simulation should consider the added masses in the equations of motion. The concept of added masses deals with the inertia added to a system, since an accelerating or decelerating body moving into a fluid displaces a volume of the neighboring fluid. The aim of this paper is to provide designers with the added masses matrix for more than twenty Lighter Than Air vehicles with unconventional shapes. Starting from a CAD model of a given shape, by applying a panel-like method, its external surface is properly meshed, using triangular elements. The methodology has been validated by comparing results obtained with data available in literature for a known benchmark shape, and the inaccuracies of predictions agree with the typical precision required in conceptual design. For each configuration, a CAD model and a related added masses matrix are provided, with the purpose of assisting the practitioner in the design and flight simulation of modern airships and scientific balloons.

• Structural Engineering and Mechanics
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• 제56권6호
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• pp.959-982
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• 2015

In this study, a non-stationary random earthquake Clough-Penzien model is used to describe earthquake ground motion. Using stochastic direct integration in combination with an equivalent linear method, a solution is established to describe the non-stationary response of lead-rubber bearing (LRB) system to a stochastic earthquake. Two parameters are used to develop an optimization method for bearing design: the post-yielding stiffness and the normalized yield strength of the isolation bearing. Using the minimization of the maximum energy response level of the upper structure subjected to an earthquake as an objective function, and with the constraints that the bearing failure probability is no more than 5% and the second shape factor of the bearing is less than 5, a calculation method for the two optimal design parameters is presented. In this optimization process, the radial basis function (RBF) response surface was applied, instead of the implicit objective function and constraints, and a sequential quadratic programming (SQP) algorithm was used to solve the optimization problems. By considering the uncertainties of the structural parameters and seismic ground motion input parameters for the optimization of the bearing design, convex set models (such as the interval model and ellipsoidal model) are used to describe the uncertainty parameters. Subsequently, the optimal bearing design parameters were expanded at their median values into first-order Taylor series expansions, and then, the Lagrange multipliers method was used to determine the upper and lower boundaries of the parameters. Moreover, using a calculation example, the impacts of site soil parameters, such as input peak ground acceleration, bearing diameter and rubber shore hardness on the optimization parameters, are investigated.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.451-462
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• 2024

In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the remote steering system's conceptual design and simulation analysis. A Square Corrugated Waveguide (SCW) of 65 × 65 mm has been designed with an optimized length of 9.35 m. By changing the relative length of the waveguide, the transmission efficiency of the SCW is optimized within the range of steering angles ±12°. Different error factors are investigated in detail, and corresponding acceptable error ranges are provided. Considering these error factors and ignoring ohmic losses and thermal effects, the relative transmission efficiency of the SCW is estimated to be >98 % within the steering angle range. A matching steering unit for the SCW is designed, which consists of an ellipsoidal focusing mirror and a steerable flat mirror. The detailed design of the steerable mirror motion trajectory is presented. Also, the influence of the possible beam incident errors caused by the steering unit on the transmission efficiency is analyzed in detail.