• 한국안광학회지
• /
• 제13권4호
• /
• pp.121-126
• /
• 2008

목적: 단안 과교정 및 저교정으로 유발된 부동시에서 정상적인 양안시기능을 유지하기 위해 필요한 최소한의 교정도수를 알아보고자 하였다. 방법: 안질환의 병력이 없는 20대의 성인 남녀를 대상으로 우위안 및 비우위안에 각각 과교정 및 저교정으로 부동시를 유발한 후 40 cm의 근거리에서 Titmus-fly stereotest 시표로 입체시를 측정하였다. 결과: 우위안 또는 비우위안에 구면렌즈를 부가하여 부동시를 유발한 경우, 가입도수의 증가에 따라 입체시는 감소하였으며 특히 (+)구면렌즈 가입에 따른 최초의 입체시 감소는 (-)구면렌즈 가입에 의한 입체시 감소보다 현저하였다. 또한 우위안에 유발시킨 부동시의 경우가 비우위안에 유발시킨 부동시보다 입체시 감소의 정도가 두드러졌다. 결론: 유발된 부동시에서 입체시는 비우위안을 완전교정하고 우위안에 (+)구면렌즈 도수를 증가시킬수록 두드러지게 감소하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.690-695
• /
• 2000

This article deals with the analytic results on the development and application of the Spherical CVT. The Spherical CVT is marked by its simple configuration, the infinite torque multiplication characteristic, and the smooth transitions between forward/neutral/reverse states of output speed. In this study, we describe the conceptual principles behind the Spherical CVT and some applications of it, which we developed recently. And, we propose the shifting algorithm based on the analytic consideration of CVT powertrain system. Contrary to conventional shifting algorithms using the OOL(optimal operating line) of the power source, the proposed shifting algorithm is represented as a $2^{nd}$ order equation in an explicit form, and it reveals the possibility of theoretic design of all optimal controller. As an example, we present numerical results that demonstrate the energy saving possible and the proposed shifting algorithm from the use of the Spherical CVT over standard reduction gear unit, using an ideal dc motor model.

• 한국정밀공학회지
• /
• 제25권2호
• /
• pp.43-48
• /
• 2008

This paper proposes a new method for measuring the power of spherical and cylindrical lens with 6 points light source, which is composed of a LED and six holes, and magnification ellipse fitting algorithm. Each measured diagonal length of 6 points light source is determined by the target lens power. After finding the center position of each light point with threshold method, 3 axis-diagonal lengths were calculated. The long axis and short axis power of cylindrical lens can be calculated by using magnification ellipse fitting algorithm with the magnification relationships between the initial diagonal lengths and the measured diagonal lengths changed by lens power.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.838-839
• /
• 2011

The spherical motor is very valuable actuator, because the motor can operate as multi-degree of freedom rotation. Especially, the motor is useful machine for robot's joint by reason of high efficiency, compact size, high power, precise control, etc. These characteristics of spherical motor have to require continuously research. Therefore, in this paper, two different types of spherical motor are compared and double-airgap spherical motor as novel stucture is introduced.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.647-650
• /
• 2001

In case of bent axis type axial piston hydraulic pump or motor, hydrostatic bearing used to achieve the lubrication effect on the mechanical sliding contact areas between the following pairs ; piston shoe and swash plate, valve plate and cylinder block, piston and cylinder block, etc. In this research, we designed two pairs of spherical ball joint in witch connecting rod piston end. The one is not hydrostatic bearing, the other is designed with spherical hydrostatic bearing in point of view minimum pumping power loss. By varying supply pressure on the piston, we can know that it is possible to reduce the friction torque by using hydrostatic bearing designed one. Finally, by comparing the results of driving torque between the two models, it was verified that the spherical hydrostatic bearing is well designed.

• 대한기계학회논문집
• /
• 제18권10호
• /
• pp.2501-2513
• /
• 1994

In this paper, a compact, light-weight, universal, spherical 3-degree-of-freedom, parallel-structured manual controller with high reflecting-force capability is implemented. First, the position analysis, kinematic modeling and analysis, force reflecting transformation, and applied force control schemes for a parallel structured 3 degree-of-freedom spherical system have been described. Then, a brief description of the system integration, its actual implementation hardware, and its preliminary analysis results are presented. The implemented parallel 3 degree-of-freedom spherical module is equipped with high gear-ratio reducers, and the friction due to the reducers is minimized by employing a force control algorithm, which results in a "power steering" effect for enhanced smoothness and transparency (for compactness and reduced weight).d weight).

• 전기학회논문지
• /
• 제57권8호
• /
• pp.1362-1370
• /
• 2008

This paper describes the design and characteristic analysis of a novel 3-DOF(Degree of Freedom) spherical motor. For multi DOF actuating, several numbers of motors have been used. By the using of normal motors they connected each other in single joint, is necessary to a several type of complex power transmission devices. The 3-DOF spherical motor can drive roll, pitch, and yaw motion in only one unit and it is not necessary to use additional gears and links parts. Therefore the using of 3-DOF spherical motor can eliminate; combined effects of inertia, backlash, non-linear friction, and elastic deformation of gears. In this paper, we propose the novel structured 3-DOF spherical motor and derive its principles of operation. Firstly, we designed concept model of novel structured 3-DOF spherical motor. Next, we derive the control method by calculating the currents. Also, to have intuitive driving control, we express the rotor position in equivalent angle-axis system and determine the exciting period of currents from the calculation result of the currents. To verify the control method, we calculated the currents by the position of rotor. and then we analyzed the characteristics by 3D Finite Element Method when the calculated currents are excited.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권8호
• /
• pp.863-869
• /
• 2006

A new CVT, the inner spherical traction CVT (ISCVT) is introduced. Transmission of the most scooters is the self-controlled variable pulley-belt type of CVT having some disadvantages in the fuel consumption and the limitation of the transmittable power due to the slippage between the belt and pulley. Unlike this, ISCVT controlled directly by driver is more efficient and the contact mechanism having the same line of contact normal of the spherical rotors of different radii on common center causes that the power density and torque capacity are remarkably improved. The prototype with the specifications of 50cc scooter is designed and tested.

• Steel and Composite Structures
• /
• 제18권3호
• /
• pp.693-709
• /
• 2015

In this article, nonlinear free vibration behaviour of functionally graded spherical panel is analysed. A nonlinear mathematical model is developed based on higher order shear deformation theory for shallow shell by taking Green-Lagrange type of nonlinear kinematics. The material properties of functionally graded material are assumed to be varying continuously in transverse direction and evaluated using Voigt micromechanical model in conjunction with power-law distribution. The governing equation of the shell panel is obtained using Hamilton's principle and discretised with the help of nonlinear finite element method. The desired responses are evaluated through a direct iterative method. The present model has been validated by comparing the frequency ratio (nonlinear frequency to linear frequency) with those available published literatures. Finally, the effect of geometrical parameters (curvature ratio, thickness ratio, aspect ratio and support condition), power law indices and amplitude of vibration on the frequency ratios of spherical panel have been discussed through numerical experimentations.

• International Journal of Automotive Technology
• /
• 제8권5호
• /
• pp.593-598
• /
• 2007

A new continuously variable transmission for bicycles(B-CVT) is developed by using a traction drive mechanism having inner and outer spherical rotors. The B-CVT has high power efficiency, large torque capacity, improved drivability and good packageability. The ratio change mechanism for the B-CVT is very simple, in contrast with other traction drive CVTs. After completing a conceptual design, a performance analysis and a detail design, a prototype of the B-CVT has been manufactured. The prototype has rated power of 100 watts, pedal speed of 6 rad/s and an overall speed ratio of 1.0-4.0. A bench test and an actual bicycle test have been performed to verify the practicability of the B-CVT.