• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1185-1187
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• 1987

Digital systems are increasingly being used in the ranges of many control engineering. The residue number system offers the possibility of high speed operation and error correction. The compact self-checking pulse-train residue arithmetic circuit is proposed. A fault tolerant digital filter is practically implemented using these proposed circuits.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.114-119
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• 1991

An input estimation technique for tracking filter(CHP algorithm) suggested by Y.T. Chan et. al. has bad performance for low maneuvering targets. In this paper, two maneuver detection algorithms are applied to Singer's target model. First, an CHP input estimation technique is applied to 9 state target model. Second, we construct a maneuver detection and correction technique using pseudo acceleration measurements, which are derived directly from measurements. These two filters have good performance for even the low maneuvering targets.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.520-522
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• 2000

디지털영상을 상향표본추출(upsanpling)의 방법으로 확대하여 해상도를 높이는 경우에 확대한 영상은 확대 전의 영상에 비해 해상도는 높아지지만 흐려지거나 계단현상이 생기게 되어 영상의 품질은 저하된다. 본 연구에서는 확대된 영상에서 생기는 이와 같은 문제점을 보완하는 상향표본추출 모델을 제안한다. 제안된 모델은 8-이웃(8-neighborhood)과 가우시안 필터(Gaussian filter)를 이용하여 확대된 영상의 증가된 픽셀들의 픽셀값을 부여하여 확대 전 영상이 가진 특성이 확대 후에도 균질하게 유지될 수 있도록 하고 계단현상도 완화한다. 그리고 감마 교정(Gamma correction)을 이용하여 영상의 흐름 정도를 개선한다.

• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1779-1785
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• 2018

In this paper, we propose an error correction method to improve the accuracy of human activity recognition using sensor event data obtained by smart devices such as wearable and smartphone. In the context awareness through the smart device, errors inevitably occur in sensing the necessary context information due to the characteristics of the device, which degrades the prediction performance. In order to solve this problem, we apply Kalman filter's error correction algorithm to compensate the signal values obtained from 3-axis acceleration sensor of smart device. As a result, it was possible to effectively eliminate the error generated in the process of the data which is detected and reported by the 3-axis acceleration sensor constituting the time series data through the Kalman filter. It is expected that this research will improve the performance of the real-time context-aware system to be developed in the future.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.103-105
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• 2004

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics and power factor simultaneously in unified active power filter systems combined with shunt passive filters is proposed, where no low/high-pass filter are used in deriving the reference voltage for compensation. Using digital all-pass filters, the phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage. The amplitude of d-axis current in a series filter is controlled as zero for power factor correction. The validity of the proposed control scheme has been verified by experimental results.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.110-115
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• 1998

An axisymmetric Navier-Stokes procedure has been developed to analyze the pulse jet flow in a ceramic filter unit for the dust dislodging process. Using Baldwin-Lomax turbulence model as a closure relationship, the SIAF(Scalar Implicit Approximate Factorization) algorithm together with the ${\delta}^k-Correction$ iterative time marching scheme is adopted to solve the unsteady compressible Navier-Stokes equations. After some validation tests, the code has been applied to solve the pulse jet flow and examine the effects of geometry and reservoir pressure condition on the pressure level inside the filter unit. To avoid dealing with the uncertainty of such factors as the cohesion of the collected dust and the adhesion of the dust to the medium and also to simplify the analysis, the filter wall is assumed to be impermeable. The results for various test cases are presented.

• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.2
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• pp.1-11
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• 2021

Salt and pepper is a type of impulse noise. It may appear due to an error in the image transmission process and image storage memory. This noise changes the pixel value at any position in the image to 0 (in case of pepper noise) or 255 (in case of salt noise). In this paper, we present an algorithm for SAP noise reduction. The proposed method consists of three steps. In the first step, the location of the SAP noise is detected, and in the second step, the pixel value of the detected location is restored using a weighted average of the surrounding pixel values. In the last step, a reliability matrix around the reconstructed pixels is constructed, and additional correction is performed with a weighted average using this. As a result of the experiment, the proposed method appears to have similar or higher objective and subjective image quality than previous methods for almost all SAP noise ratios.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.219-228
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• 2007

In this paper, we present a novel blind adaptive multiuser detector structure and three robust recursive filters to improve the performance in CDMA environments: Sigma point kalman filter (SPKF), particle filter (PF), and Gaussian mixture sigma point particle filter (GMSPPF). Our proposed robust recursive filters have superior performance over a conventional extended Kalman filter (EKF). The proposed multiuser detector algorithms initially use Kalman prediction form to estimated channel parameters, and unknown data symbol be predicted. Second, based on this predicted data symbol, the robust recursive filters (e.g., GMSPPF) is a refined estimation of joint multipaths and time delays. With these estimated multipaths and time delays, data symbol detection is carried out (Kalman correction form). Computer simulations show that the proposed algorithms outperform the conventional blind multiuser detector with the EKF. Also we can see it provides a more viable means for tracking time-varying amplitudes and time delays in CDMA communication systems, compared to that of the EKF for near-far ratio of 20 dB. For this reason, it is believed that the proposed channel estimators can replace well-known filter such as the EKF.

• Journal of the Korea Society of Computer and Information
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• v.21 no.12
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• pp.35-41
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• 2016

In this paper, we propose a new real-time dead pixel detection method based on spatial compare filtering, which are usually used in the small target detection. Actually, the soft dead and the small target are cast in the same mold. Our proposed method detect and remove the dead pixels as applying the spatial compare filtering, into the pixel outputs of a detector after the non-uniformity correction. Therefore, we proposed method can effectively detect and replace the dead pixels regardless of the non-uniformity correction performance. In infrared camera, there are usually many dead detector pixels which produce abnormal output caused by manufactural process or operational environment. There are two kind of dead pixel. one is hard dead pixel which electronically generate abnormal outputs and other is soft dead pixel which changed and generated abnormal outputs by the planning process. Infrared camera have to perform non-uniformity correction because of structural and material properties of infrared detector. The hard dead pixels whose offset values obtained by non-uniformity correction are much larger or smaller than the average can be detected easily as dead pixels. However, some dead pixels(soft dead pixel) can remain, because of the difficulty of uncleared decision whether normal pixel or abnormal pixel.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.139-146
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• 2023

Maritime object detection systems, which detects small maritime obstacles such as fish farm buoys and visualizes distance and direction, is equipped with a 3-axis gimbal to compensate for errors caused by hull motion, but there is a limit to distance error corrections necessitated by the vertical movement of the camera and the maritime object due to wave motions. Therefore, in this study, the distance error of maritime object detection systems caused by the movement of the water surface according to the external environment is analyzed and corrected using average filter and moving average filter. Random numbers following a Gaussian standard normal distribution were added to or subtracted from the image coordinates to reproduce the rise or fall of the buoy under irregular waves. The distance calculated according to the change of image coordinates, the predicted distance through the average filter and the moving average filter, and the actual distance measured by laser distance meter were compared. In phases 1 and 2, the error rate increased to a maximum of 98.5% due to the changes of image coordinates due to irregular waves, but the error rate decreased to 16.3% with the moving average filter. This error correction capability was better than with the average filter, but there was a limit due to failure to respond to the distance change. Therefore, it is considered that use of the moving average filter to correct the distance error of the maritime object detection system will enhance responses to the real-time distance change and greatly improve the error rate.