• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.515-518
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• 1994

Holographic interferometry is a useful whole-field nondestructive testing for measuring deformations and vibrations of engineering structure. A diverging beam is used as a light source int the most of holographic interferometer practically. For a relatively small object the optical arrangement using a collimated light source has no difficulty in use technically, but for a large object it is difficult to use a collimated beam. In this study we calculate the error of measured displacement from the sensitivity vector dominated by the geometry of optical arrangement for holographic interferometer and show the result obtained with 2-D plots. A Plane surface and a cylindrical surface were chosen as objects to be calculated and computer analysis was carried out for the cases of a diverging beam and a collimated one.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.696-702
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• 2015

This paper suggests a new method for making a navigation path by using Bezier curve in order to improve the navigation performance used to avoid obstacles during a robot soccer game. We analyzed the advantages and disadvantages of both vector-field and limit-cycle navigation methods, which are the mostly widely used navigation methods for avoiding obstacles. To improve the disadvantages of these methods, we propose a new design technique for generating a more proper path using Bezier curve and describe its advantages. Using computer simulations and experiments, we compare the performance of vector-field navigation with that of Bezier curve navigation. The results prove that the navigation performance using Bezier curve is relatively superior to the other method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.161-163
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• 2007

기존의 텍스트 추출을 위한 이진화 방법은 입력 이미지를 명도 이미지로 변환한 뒤 이진화 하는 방법을 사용하였다. 이러한 방법은 칼라 이미지에서는 극명히 구분되는 색이라 할지라도 명도 이미지로 변환하는 과정에서 같은 밝기를 같게 되는 경우(예를 들어, 배경은 붉은색, 텍스트는 초록색), 텍스트를 추출하는 데 어려움이 있다. 본 논문에서는 이러한 문제를 해결하기 위해 입력 이미지를 R, G, B로 분리하고 각각을 이진화 하여 텍스트를 추출하고 다해상도 웨이블릿(Wavelet) 변환을 이용하여 텍스트의 획 특징을 추출하여 추출된 특징들을 SVM(Support Vector Machine) 분류기로 검증하여 최종 텍스트 영역을 확정한다. 제안한 방법을 적용함으로써 명도 정보만으로는 추출하기 어려웠던 텍스트 영역을 효과적으로 추출하고 텍스트와 구별하기 어려운 영역을 획수준으로 검증할 수 있었다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.943-948
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• 1994

The vector sum excited linear prediction(VSELP) coding gives high quality of synthetic speech at bit rates as low as 4.8kbps, but its computational complexity is prohibitive for real time applications. In this paper, we propose a method to reduce the computations of the VSELP codebook search procedure. The proposed method reduces the search space efficiently, before applying every linear combination of the basis vectors to the codebook search procedure. It decides whether is can fix the combination coefficient of each basis vector using heuristics so that the number of combinations decreases. It has been shown that the proposed method retains good quality of synthetic speech and reduces the computations of codebook search procedure by more than 40% of the origin.

• Nuclear Engineering and Technology
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• v.4 no.1
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• pp.11-22
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• 1972

Determination of a two-point boundary value problem is the key of finding the control function u(t) with the application of the fundamental idea of Minimum principle. The late development shows the discovery of the initial costate vector for the solution of a two-point value problem. As a new technique of determining the optimal control function, Newton's Sequential method is examined about a number of engineering problems and found available.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2004-2007
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• 2002

In the linear combination type stereophonic echo canceller, it is known not to converge the coefficient vector of the adaptive filter to a correct echo path. In this report, we analyze the convergence value of the filter coefficient vector of the stereo echo canceling algorithm using input signals of all channels in relation to this problem. In this analysis, one of the two inputs to the un-known system and adaptive one are assumed to be a delayed and attenuated version of the other signal as a model of the input signal with a strong cross-correlation. As a result, it is shown for the coefficient vectors not to converge to echo paths, and nor to converge to the value which depends on the time delay and the attenuation of the input signal. We show that the computer simulation result are corresponding to our analytical results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.509-513
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• 2002

This paper presents a semi-blind Minimum Mean Square Error (MMSE) beamforming adaptive algorithm used far OFDM/CDMA combined system. The proposed algorithm exploits the transmitting pilot signal in the initial period of the transmission to update the weight vector. Then it applies the blind adaptive period to update the weight vector, in which the pilot signal is no longer used. The derivation of the algorithm based on the Mean Square Error (MSE) criterion is also presented. Computer simulation is carried out to verify the performance of the proposed approach.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.509-516
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• 2015

The overmodulation characteristics of a carrier-based medium vector pulse width modulation (CBMVPWM) are examined in this study. CBMVPWM can completely eliminate leakage currents in a three-phase, three-level inverter using only the switching states with the same common mode voltage even in an overmodulation operation. The analytic equations for the magnitude of the output voltage and the switching frequency are derived for overmodulation operation, and the effect of dead time on the leakage current is demonstrated. This study presents the operating principle of CBMVPWM, basic overmodulation features, and simulations and experiments for operating verification.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1236-1238
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• 2000

This paper considers the problem of eliminating harmonics in the inverter output waveforms. The approach is based on the minimization of the current harmonics in the induction motor by space vector modulation method. Reference voltage is compensated with injection of controlled current harmonics which are calculated to reduce current harmonics through sampled current harmonic analyzing algorithm. The theoretical analysis is carried out using computer simulation. It is verified that proposed SVM technique could reduce current harmonic component and improve THD.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.4
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• pp.30-35
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• 2009

Effective-pivot effects on the thrust vector control performance of the flexible seal nozzle to be used to control the flight direction of missile were investigated by computer simulation. $2^3$-Design of experiment technique was applied and ADMAS was used for the surrogate technique. As a result, radial pivot position had more influence upon the nozzle actuating performance than axial pivot position. Connecting method of actuator was also important factor in determining effective-pivot effects on the thrust vector control performance of the flexible seal nozzle.