• 한국융합학회논문지
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• 제8권11호
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• pp.15-20
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• 2017

최근 IT 산업의 발전으로 다양한 분야에서 컴퓨터 융합 기술에 대한 관심이 높아지고 있다. 특히 반도체 분야에서 생산 공정에 반도체 소자의 결함을 검사하기 위하여 카메라와 컴퓨터를 융합한 비전 시스템을 많이 사용하고 있다. 이러한 영상 관련 시스템들은 데이터를 처리하는 과정에서 열화 현상이 발생하기에 주유한 요인인 잡음을 제거하기 위한 다양한 연구가 이루어지고 있다. 이에 본 논문에서는 BGA 패키지 소자를 대상으로 양산 과정에서 결함을 사전에 인식하여 불량을 검출하기 위하여 영상 데이터의 잡음제거에 많이 사용하고 있는 가우시안 필터, 미디언 필터, 평균 필터를 이용한 측정 시스템을 제안한다. 제안 시스템을 BGA 패키지 생산 공정에 적용하면 신속하게 양품과 불량을 판정할 수 있어 생산성이 향상될 것으로 기대된다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.268-271
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• 2003

There are several methods for the design of 2D filter. Notable among them is McClellan transform method. This transform allows us to obtain a high order 2D FIR filter through mapping the 1D frequency points of a 1D prototype FIR filter onto 2D frequency contours. We design 2D filter using this transform. Then we notice for mapping deviation of the 2D filter. In this paper, Quadratic programming (QP) method allows us to obtain coefficients of McClellan transform. Then we compare deviation of QP method with least-squares(LS) method. Elliptic filter is used for comparison. The optimal cutoff frequencies of a 1D filter are obtained directly from the QP method. Also several problem of LS method are solved.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.165-168
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• 2000

In this paper, the polyphase filter which has good ripple characteristic in the passband is proposed. This filter consists of the digital all-pass filter of parallel structure and it is the half-band filter with all zeros in unit circle. To approach easily in designing hardware, we determined the coefficients to the 16bit 1.15 format. To evaluate the performance of this filter, we analyzed the phase characteristic in each branch and simulated each filter with small coefficients. From the result, we have got to good ripple characteristic and also analyzed the fifth and the seventh, and compared them with four part : ripple, group delay, transition bandwidth, stopband attenuation.

• ETRI Journal
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• 제33권5호
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• pp.695-703
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• 2011

The number of adders and critical paths in a multiplier block of a multiple constant multiplication based implementation of a finite impulse response (FIR) filter can be minimized through common subexpression elimination (CSE) techniques. A two-bit common subexpression (CS) can be located recursively in a noncanonic sign digit (CSD) representation of the filter coefficients. An efficient algorithm is presented in this paper to improve the elimination of a CS from the multiplier block of an FIR filter so that it can be realized with fewer adders and low logical depth as compared to the existing CSE methods in the literature. Vinod and others claimed the highest reduction in the number of logical operators (LOs) without increasing the logic depth (LD) requirement. Using the design examples given by Vinod and others, we compare the average reduction in LOs and LDs achieved by our algorithm. Our algorithm shows average LO improvements of 30.8%, 5.5%, and 22.5% with a comparative LD requirement over that of Vinod and others for three design examples. Improvement increases as the filter order increases, and for the highest filter order and lowest coefficient width, the LO improvements are 70.3%, 75.3%, and 72.2% for the three design examples.

• ETRI Journal
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• 제34권3호
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• pp.379-387
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• 2012

In this paper, an error compensation technique for a dead reckoning (DR) system using a magnetic compass module is proposed. The magnetic compass-based azimuth may include a bias that varies with location due to the surrounding magnetic sources. In this paper, the DR system is integrated with a Global Positioning System (GPS) receiver using a finite impulse response (FIR) filter to reduce errors. This filter can estimate the varying bias more effectively than the conventional Kalman filter, which has an infinite impulse response structure. Moreover, the conventional receding horizon Kalman FIR (RHKF) filter is modified for application in nonlinear systems and to compensate the drawbacks of the RHKF filter. The modified RHKF filter is a novel RHKF filter scheme for nonlinear dynamics. The inverse covariance form of the linearized Kalman filter is combined with a receding horizon FIR strategy. This filter is then combined with an extended Kalman filter to enhance the convergence characteristics of the FIR filter. Also, the receding interval is extended to reduce the computational burden. The performance of the proposed DR/GPS integrated system using the modified RHKF filter is evaluated through simulation.

• 한국산업융합학회 논문집
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• 제26권6_2호
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• pp.1163-1169
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• 2023

In this study, the flow characteristics of the filter system were analyzed due to the effect of the density of the filter in the triple filter system. Flow analysis was performed as a flow passing through a porous medium. The flow characteristics of each filter system were analyzed by arranging filters with different densities in the forward flow flow and the reverse flow. The arrangement order of the triple filters was excellent in the case of forward fluid flow and in the case of higher density from the inside to the outside filter. In the reverse flow filter system, the performance of the system was the best in the case of reverse order filter arrangement. As a result of the analysis, Case II, which showed a pressure drop rate of 5.65% for forward flow, was the best in the reverse direction with a pressure drop rate of 14.25%. Considering reverse and forward flows, it was found that the optimal filter arrangement was most effective when the intermediate filter was the densest, and the inner or outer filter was less dense.

• 한국융합학회논문지
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• 제4권4호
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• pp.41-48
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• 2013

Observer design for system with unknown input was carried out. First, Kalman filter was considered to estimate system state with White noise. With the results of Kalman filter design, state observer, controller properties, including controllability and observability, and the Kalman filter structure and algorithm were also studied. Kalman filter algorithm was applied to Position and velocity measurement based on Kalman filter with white noise, and it was constructed and achieved by programming based on Matlab programming. Finally, observer for system with unknown input was constructed with the help of Gershgorin's disc theorem. With the designed observer, system states was constructed and applied to system with unknown input. By simulation results, estimation performance was verified. In this project, state feedback control theory, observer theory and relevant design procedure, as well as Kalman filter design were understood and used in practical application.

• 정보처리학회논문지A
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• 제11A권2호
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• pp.203-206
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• 2004

저자는 등각사상을 구하기 위한 기존의 여러 Theodorsen 방정식의 해법 중 가장 유효한 해법으로 알려져 있는 Wegmann의 방법을 다룬바 있다. Wegmann의 방법으로 수치실험을 한 결과 난이도가 높다고 예상되는 문제에 있어 수렴했다가 발산을 하는 불안정현상이 나타났으며 수렵하지 않는 불안정현상의 원인을 분석하여 저주파필터를 적용한 새로운 반복법을 제안하였다. 원래의 Wegmann 반복법으로는 발산하는 모튼 문제에 있어서 새로 제안한 방법에 의해서 수렴하는 수치실험 결과를 얻었는데 본 논문에서는 저주파필터를 적용한 Wegmann해법에 의해 실험적으로 수렴한 결과를 Fourier 분석기법에 의해 이론적으로 증명한다.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.615-621
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• 2023

In this study, flow analysis of single, double, and triple filter systems of cylindrical structures was performed to analyze the flow characteristics of each filter. As a result of the flow analysis of the filter system, the number of filters and the pressure drop rate tend to be proportional to each other. It was found that the area passing through the inside of the filter had almost the same pressure. The maximum pressure drop rate of the triple filter system was about 14.9% for the forward-flow and about 12.4% for the reverse-flow. It was determined that the performance of the filter was stable within 20% of the allowable pressure drop rate of the filter system, which is the standard presented to the Korea Water Technology Certification Institute(KWTCI). In the future, a study on the decompression characteristics of the filter system according to the effect of the arrangement interval and filter density of the triple filter will be conducted.

• The Journal of the Acoustical Society of Korea
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• 제27권2E호
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• pp.64-68
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• 2008

This paper investigates noise reduction performance and performs convergence analysis of a Variable Error Data Normalized Step-Size Least Mean Square(VEDNSS LMS) algorithm. Adopting VEDNSS LMS results in higher system complexity, but noise is reduced providing fast convergence speed Mathematical analysis demonstrates that tap coefficient misadjustment converges. This is confirmed by computer simulation with the proposed algorithm.