• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.442-447
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• 2005

This paper presents an application of overlapping-grid technique for probe feeding simulation. The overlapping grid technique is used to solve contour path problem. In this technique, field interpolation is very important to make communication between two coordinates. By applying overlapping-grid technique, error of contour path in probe feeding simulation is reduced.

• Journal of the Korean Mathematical Society
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• v.34 no.2
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• pp.293-307
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• 1997

In this paper we present the $L^2$-estimation for the kernel $K_n$ of the remaider term for the Gaussian quadrature with respect to one of four Chebyshev weight functions and the error bound of the type on the contour $$ $\mid$R_n(f)$\mid$ \leq \frac{2\pi}{\sqrt{l(\Gamma)}} max_{z\in\Gamma}$\mid$f(z)$\mid$ (\smallint_\Gamma $\mid$K_n(z)$\mid$^2$\mid$dz$\mid$)^\frac{2}{1}, $$ where $l(\Gamma)$ denotes the length of the contour $\Gamma$.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.105-113
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• 2006

This work is concerned with the development of digital contouring controller for multi-axial servosystems. Digital optimal contouring controller is proposed to coordinate each of the controllers of multiple feed drives and specifically improve the contouring performance. The optimal control formation includes the contour error explicitly in the performance index to be minimized. The contouring control is exercised for straight line and circular contours. Substantial improvement in contouring performance is obtained for a range of contouring conditions. Both steady state and transient error measures have been considered. The simulation study presented has established the potential of the proposed controller to improve contouring performance.

• IE interfaces
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• v.8 no.3
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• pp.133-139
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• 1995

Free from curves and surfaces are frequently used in designing engineering products such as car, ship, airplane, and hosing of electronic households. In many aspect, it is very nice to use the cutter radius compensation function of CNC controller when contour machining a 2-dimensional curve. However, if the 2D curve is a parametric spline, it is not easy to apply the cutter radius compensation function of CNC controller to the NC data obtained from many commercial CAM system. This is mainly due to the error magnification effect when offsetting line segments with inevitable round-off error at their vertices. Proposed in this paper is an approach to contour machining a 2D parametric spline while using cutter radius compensation. Some implementation results are included.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.8
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• pp.658-666
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• 1989

In this paper, an efficient algorithm for estimation volume and surface area and a reconstruction algorithm for 3-dimensional graphics are presented.In order to improve computing efficiency, the graph theory is utilized and the algorithm to obtain proper contour points is developed by considering several tolerances. Search for the contour points is limited by the change of curvature of cross sectional contour to provide efficiency in searching the minimum cost path. In computer simulation of these algorithms, the results show that, for the tolerance values of 1.001 and 1.002, the execution time reduced to 66%-80% and the error for the measured value is less than 3%. The reconstructed 3-dimensional images from the cross sections can be analyzed in many directions using the graphic scheme.

• Phonetics and Speech Sciences
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• v.4 no.2
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• pp.51-59
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• 2012

The purpose of this study is to examine the pitch pattern of Korean accentual phrases produced by Chinese Korean-learners in the reading of a Korean text. Korean accentual phrase is determined by a specific F0 contour. And the pitch contour of APs differ depending on their length and the nature of initial segment. In order to examine if Chinese speakers are also aware such a phonetic properties, we have examined the AP pitch contours produced by 15 Chinese speakers differing in proficiency, and compared them to pitch contours produced by six Korean native speakers. The results show that Chinese speakers' pitch errors were observed in initial segment-tone interaction and in type of pitch patterns. However, even though Chines speakers produced the same type of pitch patterns, internal tonal modulation differs from native speakers. Finally, on the basis of theses results, we proposed a teaching method that visualizes the F0 contour.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.3
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• pp.290-296
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• 2005

The contour method is based on the elastic superposition principle, and relies on deformations that occur when a residually stressed part is cut along a plane. During the cut, the part is constrained at a location along the cut so that deformations are restrained as much as possible. The displacement is applied to an elastic FE model of the half. When plasticity is involved in the relaxation process, the superposition principle is no longer valid, and stress error in the resulting measurement of residual stress would be caused. Residual stress states in a laser peened Ti-6Al-4V strip were taken for the FE simulation.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.97-111
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• 1995

In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.71-76
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• 2014

In this paper, we propose a SMMA(Sliced-Multi Modulus Algorithm) adaptive blind equalization algorithm with Flag for high order QAM system. SMMA has improved characteristics by applying the multi contour to MMA. However, SMMA still has a limit that the mismatch problem causes the residual error in the steady state is large. In order to significantly reduce the residual error in the steady state, we propose SMMA, which is controlled by the binary Flag of '1 'or '0' obtained from SMMA and a decision-directed algorithm, and analyze the performance of the proposed algorithm. By computer simulation, it is confirmed that the proposed algorithm has improved performance highly in terms of a residual ISI and a residual error in the steady state compared with MMA and SMMA.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.589-597
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• 2011

In this paper, optimal tuning of a cross-coupled controller linked with the feedforward controller and the disturbance observer is studied to improve contouring and tracking accuracy as well as robustness against disturbance. Previously developed integrated design and optimal tuning methods are applied for developing the robust tuning method. Strict mathematical modeling of the multivariable system is formulated as a state-space equation. Identification processes of the servomechanism are conducted for mechanical servo models. An optimal tuning problem to minimize both the contour error and settling time is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servo control system. Constraints such as relative stability, robust stability and overshoot, etc. are considered for the optimization. To verify the effectiveness of the proposed optimal tuning procedure, linear and circular motion experiments are performed on the xy-table. Experimental results confirm the control performance and robustness despite the variation of parameters of the mechanical subsystems.