• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.247-254
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• 2006

For more accurate navigation, lever arm compensation is considered. The compensation method for GPS and an odometer is introduced and new compensation methods are proposed for an odometer to consider the effect of coordinate transformation errors and the scale factor error. The methods are applied to a GPS/INS/odometer integrated system and the simulation and experimental results show its effectiveness.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.38-41
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• 2001

A new 2-D braided textile metal matrix composite was developed and characterized. The constituent materials consist of PAN type carbon fiber as reinforcements and pure aluminum as matrices. The braided preforms of different braider yarn angles were fabricated. For a fixed bundle size of 12K, three braider yarn angles was selected: $30^{\circ}$, $45^{\circ}$, and $60^{\circ}$. The braided preforms were infiltrated with pure Al by vacuum assisted squeeze casting. Through the investigation of melt pressing methods and the effects of process parameters such as applied pressure, and pouring temperature, the optimal process conditions were identified as follows: applied pressure of 60MPa, pouring temperature of $800^{\circ}C$. Using the measured geometric parameters, 3-D engineering constants of metal matrix composites have been determined from the elastic model, which utilizes the coordinate transformation and the averaging of stiffened and compliance constants based upon the volume of each reinforcement and matrix material.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.188-191
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• 2002

3-D orthogonal woven carbon/Al composites were fabricated using a pressure infiltration casting method. Especially, to minimize geometrical deformation of fiber pattern and $Al_4C_3$ formation, the process parameters of the minimum pressurizing force, melting temperature, delay and holding time of molten aluminum pressurizing was optimized through the PC-controlled monitoring system. Resonant ultrasound spectroscopy (RUS) was utilized to measure the effective elastic constants of 3-D orthogonal woven carbon/Al composites. The CTE measurement was conducted using strain gages in a heating oven.

• Journal of KSNVE
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• v.7 no.4
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• pp.613-620
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• 1997

Steady and unsteady flows between rotating cylinders are of interest on lubrication, convective heat transfer and flow-induced vibration in large rotating machinery. Steady rotating flow is generated by rotating cylinder with constant velocity while the unsteady rotating flow by oscillating cylinder with homogeneoysly oscillating velocity. An analytical method is developed based on the simple radial coordinate transformation for the steady and unsteady rotating flows in concentric annulus. The governing equations are simplified from Navier-Stokes equatins. Considering the skin friction based on the radial variation of circumferential flow velocity, the torques acting on the fixed and the rotating cylinder are evaluated in terms of added-inertia and added-damping torque coefficients. The coefficients are found to be influenced by the oscillatory Reynolds number and the radius ratio of two cylinders; however, the effect of the oscillatory Reynolds number on the coefficients is minor in case of relatively low radius ratio.

• Tribology and Lubricants
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• v.24 no.1
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• pp.14-20
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• 2008

In this paper, the characteristics of trapezoidal air screws is studied. These screws can e applied to the elevator having column driving shaft. The generalized coordinate transformation technique is used to solve incompressible Reynolds' equation because the air lubricated plane is twisted. The transformed equation is discretized by the base of Finite difference method. Using Visual C++ language, a GUI program which can calculate he load carrying capacity for this kind of air screw is developed, then the design variables for these air screws is studied.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.2
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• pp.185-197
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• 1999

Heat transfer and solidification of liquid silicon in von-$K{\acute{a}}rm{\acute{a}}n$ swirling flow is investigated. The moving boundary is fixed for all times by a coordinate transformation, and finite difference method Is used to obtain the instantaneous location of the solid-liquid Interface and the heat transfer from the surfaces of solid and liquid. For small Stefan number or low wall temperature, the transient heat transfer from the surface of solid(QS(t)) is much larger than that from the liquid side of solid-liquid interface(QL(t)) and QL(t) reaches its quasi-steady-state value much faster than QS(t).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.143-149
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• 1993

An approach is presented for efficient numerical integration of the Sormnerfeld type integrals pertinent to the microstrip surface Green's function arising in the problem of an electric current point source on an infinite planar grounded dielectric substrate. This approach, valid for both lossless and lossy dielectric substrates, is based on the deformation of the integration contour via a coordinate transformation and Cauchy's residue theory, and identifies clearly the effects of surface waves. I ts useful application is in a rigorous moment method analysis of micros trip antenna arrays and microstrip guided wave structures. The efficiency and the usefulness of the present approach are emphasized through some numerical calculations of the impedance matrix elements with associated CPU times.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.245-247
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• 1992

We utilize as a processor TMS320C25 (Texas Instrument) in making a driver for a 4 pole PM synchronous servo motor. TMS320C25 has a 32bit ALU and a 16 bit hardware multiplier, and the maximum instruction execution rate is 10MIPS at 40MHz. We adopted a space vector modulation PWM method. An interesting point of this work is that PWM wave is generated by utilizing timer interrupts. Hence, in the rest of time the processor can take care of the other routine such as Park's coordinate transformation and the computation required in the feedback loops. Thus, it mates the hardware circuit very simple. Due to the decrease in the number of components, the motor drive system becomes more fault-tolerant and cost-optimized. Also, more flexibility is gained in changing the control parameters.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.16-20
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• 1988

This paper presents a new algorithm for solving the inverse kinematics in real-time applications. The end-tip movement of each link can be resolved into the basic resolution unit, .DELTA.l, which depends on link length, reduction ratio and resolution of the incremental encoder attached to the joint. When x- and y-axis projection of the end-tip movement are expressed in .DELTA.l unit, projectional increments .DELTA.x and .DELTA.y become -1, 0 or I by truncation. By using the incremental computation with these ternary value and some simple logic rules, a coordinate transformation can be realized. Through this approach, it should be noted that the floating-point arithmetic and the manipulation of trigonometric functions are completely eliminated. This paper demonstrates the proposed method in a parallelogram linkage type, two-link arm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.269-272
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• 1999

It is still hard to measure the strain distribution over entire surface of a medium or large-size stamped part even by using an automated strain measurement system. Several methods which enable to enlarge the measurement range without losing accuracy and precision are suggested in this study, The superposition of images having different high-lightened or damaged part each other results in an enhanced image. A new method for constructing the element connectivity from a line-thinned image makes it possible to identify up to 1,000 elements. And the geometry assembling algorithm is proved very efficient in which the whole area to be measured is divided into several parts ; the coordinate transformation between every two adjacent parts is obtained from the concept of the least square error ; and the 3-D shape or strain distribution over the whole surface is assembled,