• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.169-179
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• 1998

Plane mirror type laser interferometers are popularly being used in many modern ultraprecision machines, as they can perform simultaneous measurements of multiple axis positions with nanometer resolution capabilities. One important issue in this application of laser interferometers is to provide a good level of alignment between the reflecting mirrors and the laser beams so that measurement errors due to undesirable coupling effects can be avoided in multiple axis measurements In this investigation, a thorough metrological analysis is given to develop an suitable mathematical model for a precision x-y stage in which the orthogonality misalignment between the reflecting mirrors significantly affects overall x-y mea-surement results. Then a noble calibration method is suggested in which two-dimensional displacement sensors of moire gratings of concentric circles are used to realize the reversal principle of orthogonality evaluation in situ. Finally, actual experimental results are discussed to verify that the suggested method can effectively calibrate the orthogonality error with an uncertainty of 0.2667 arcsec.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3C
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• pp.170-174
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• 2011

We introduce the network coding which cooperative communication for two-way relay channel. We propose a new network coding scheme using orthogonality for cooperative communication system. The proposed network coding scheme via orthogonal mapping shows better BER performance because proposed scheme weakens error propagation which is disadvantage of DF scheme. And proposed scheme maintains same throughput compared to conventional scheme.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.159-166
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• 1987

A new family of sinusoidal orthogoal trnasform is introduced. For a derivation, a parametric sinusoidal matrix whose transform might be implemented by a suitable FFT algorithm is modeled basically on the analogy of well-known sinusoidal transform such as DCT,SCT, etc., and its orthogonality condition is calculated. The parameters satisfying orthogonality condition are determined, in a sense, by particular solution after trial and error. However more than then transform matrices not yet known are obtained. It is also shown that these transforms can be computed by a DFT. of an image.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1540-1545
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• 2001

This paper is concerned with the reverse link performance of multi-code CDMA systems in multipath fading environments. The degree of orthogonality loss among multiple spreading code channels is characterized as the orthogonality factor. It depends on various system parameters including multipath power profiles of propagation channels and the number of Paths resolved at a Rake receiver. The effect of the parameters on the system performance is then investigated in terms of bit error rate and required signal quality. The results show that multipath delay power profiles dominantly affect mutual interference among multi-code channels and multipath combining gain by bandwidth expansion is not so great due to the increase of the mutual interference. Moreover, the orthogonality factor is derived as the value of between (1/m) and 1.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.50-57
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• 2010

A high precision air bearing stage has been developed and calibrated. This linear-motor driven stage was designed to transport a glass or wafer with the X and Y following errors in nanometer regime. To achieve this level of precision, bar type mirrors were adopted for real time ${\Delta}X$ and ${\Delta}Y$ laser measurement and feedback control. With the laser wavelength variation and instability being kept minimized through strict environment control, the orthogonality of this type of control system becomes purely dependent upon the surface flatness, distortion, and assembly of the bar mirrors. Compensations for the bar mirror distortions and assembly have been performed using the self-calibration method. As a result, the orthogonality error of the stage was successfully decreased from $0.04^{\circ}$ to 2.48 arcsec.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.46-50
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• 2001

Adaptive signal processing is used to acoustic echo canceller. adaptive noise canceller and adaptive algorithm among adaptive algorithms is mainly used because the structure is simple and computa LMS algorithm has trade-off between the converge speed and the steady state error. In this paper, step-size of adaptive algorithm is varied with orthogonality Principles of optimal filter to get fasts though small steady state error. Time varying step-size is determined proportional to the maximum vector of LMS algorithm. As results of simulations, the adaptive algorithm with proposed time-v compared with conventional ones.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.303-305
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• 1993

Walsh function and transform are important analytical tools for control theory and signal processing and have wide applications in those fields, especially in the field of digital communications. Therefore there is a need for a Walsh function generator in order to realize certain applications. And a number of different desists are known. But desist and implementation of such a generator through hardware logic nay give rise to orthogonality error. To develop Walsh function generator which gets rid of orthogonality error, this paper presents a microprocessor based design and implementation method.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.1
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• pp.64-71
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• 1994

In this paper, we propose orthogonal integer transform(OIT) with general form. Considering the orthogonality and magnitude value order of the DCT Matrix whose performance is found to be close to that of the KLT, known to be optimal. The proposed OIT matrix is composed of values minimizing Hibert-Schmidt norm among integer values which satisfy the condition of orthogonality and the relative magnitudes of the DCT matrix. Comparing the OIT with the DCT, CMT, and ICT in error characteristics, transform efficiency, and maximum reducible bit, it is shown that the performance of the OIT compares more closely to that of the KLT relative to the performances of the DCT, CMT, and ICT when N=8.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.379-382
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• 2002

Among the CMM calibration techniques, the calibration with standard specimen is most accurate way to acquire the required precision. When there is no standard specimen, the calibration of CMM with itself is possible. This calibration method is called "self-calibration". In this paper, we developed self-calibration algorithm for CMM XY plane. It is possible to calculate the in-plane error and out-of-plane error of CMM with 3 different measurement of same artifact. Experimental result shows that the non-orthogonality error is dominant in in-plane error and the self-calibration result and laser interferometer measured result have almost same value.ame value.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.885-895
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• 2004

Generally, automatic design is carried out with computer simulation and the simulation models are established by investigating the correlations between the simulation and real experiments. Therefore, the experiment results are utilized as complimentary data although they are considered to be precise. Orthogonal arrays have been adopted for discrete design. A method is proposed to directly exploit the experiment results in the design process with orthogonal arrays. Experiments are allocated to some rows of an orthogonal array and computer simulations are allocated to the others. A rule for the allocation is found to keep the orthogonality. Error analysis of the design results is performed. Mathematical examples are made to verify the validity of the proposed method. Error models are defined with the examples and the design solutions from the examples are discussed.