• 한국통신학회논문지
• /
• 제22권4호
• /
• pp.706-713
• /
• 1997

In this paper, we propose a band stop filter(BSF) for reducing drag-like effect of the low pass filter(LPF), a block by block adaptive filtering method, and a motion adaptive filtering method, which show better results in terms of PSNR or human visual perception compared to the conventional method using LPF. The BSF improves the draglike effects of the low pass filter by passing temporal high frequency components of video sequences which correspond to objects with large motion. The proposed adaptive methods also improve the conventional adaptive filtering by modifying the conventional algorithm and applying the algorithms for small blocks. The simulation results show that the proposed filtering methods show better results in terms of PSNR and subjective tests in most cases. Also in case of block by block adaptive filtering, it is verified that the application of the algorithm for smaller block gives better results.

• 음성과학
• /
• 제12권4호
• /
• pp.71-76
• /
• 2005

There have been numerous studies on the enhancement of noisy speech signal. In this paper, we propose a new speech enhancement method, that is, a filtering of a dissonant frequency combined with noise suppression algorithm. The simulation results indicate that the proposed method provides a significant gain in voice clarity. Therefore if the proposed enhancement scheme is used as a pre-filter, the perceptual clarity of husky voice is greatly enhanced.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권6호
• /
• pp.2518-2533
• /
• 2020

In wireless sensor networks, adversaries may physically capture sensor nodes on the fields, and use them to launch false positive attacks (FPAs). FPAs could be conducted by injecting forged or old sensing reports, which would represent non-existent events on the fields, with the goal of disorientating the base stations and/or reducing the limited energy resources of sensor nodes on the fields. Researchers have proposed various mitigation methods against FPAs, including the statistical en-route filtering scheme (SEF). Most of these methods are based on key pre-distribution schemes and can efficiently filter injected false reports out at relay nodes through the verification of in-transit reports using the pre-distributed keys. However, their filtering power may decrease as time goes by since adversaries would attempt to capture additional nodes as many as possible. In this paper, we propose an adaptive key distribution method that could maintain the security power of SEF in WSNs under such circumstances. The proposed method makes, if necessary, BS update or re-distribute keys, which are used to endorse and verify reports, with the consideration of the filtering power and energy efficiency. Our experimental results show that the proposed method is more effective, compared to SEF, against FPAs in terms of security level and energy saving.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
• /
• pp.522-522
• /
• 2000

In this paper, two pre-filtering techniques are presented for accurately estimating the impact location of a loose part. The reason why a pre-filterng technique Is necessary in a Loose Part Monitoring System is that the effects of background noise on the signal to noise ratio (SNR) can be reduced considerably resulting in improved estimation accuracy. The first method is to take d moving average operation in the time domain. The second one is to adopt band-pass filters designed in the frequency domain such as a Butterworth filter, Chebyshev filter I & II and an Elliptic Filter. To show the effectiveness, the impact test data (signals) from the YGN3 power plant are first preprocessed and then used to estimate the loose pan impact position. Resultantly. we observed that SNR is much improved and the average estimation error is below 7.5%.

• Tribology and Lubricants
• /
• 제16권6호
• /
• pp.440-447
• /
• 2000

It's a tendency to strengthen related international laws as the importance on marine oil pollution recently becomes the issue. According to the regulation of IMO, oil discharge from ships is allowed under 15 ppm only and oil filtering equipment is essential. However, for large ships using heavy fuel oil of over S.G 0.98 and viscosity 380 cSt and system oil, it has been in difficulty to process with existing filtering type of oily water separator. Oily water pre-separator of laminated plate type which is one of gravity type separator has very simple structure and it also makes easier to maintain and repair. In another words, it fits well to process large amount of rich oil with high specific gravity. In this paper, oily water pre-separator of laminated plate type has been studied. The function of emulsified oil and 4 different types of oil have been analyzed and each character has been investigated and proved by experiments. As the result of it, the efficiency of separating oil water has been advanced by 10% in case equipped with pre-separator. In addition, the higher temperature is and the more laminated plate has, it turns out to be getting more effect.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
• /
• pp.736-739
• /
• 2006

While hyperspectral data are very rich in information, their processing poses several challenges such as computational requirements, noise removal and relevant information extraction. In this paper, the application of advanced scale-space filtering to selected hyperspectral bands was investigated. In particular, a pre-processing tool, consisting of anisotropic diffusion and morphological leveling filtering, has been developed, aiming to an edge-preserving smoothing and simplification of hyperspectral data, procedures which are of fundamental importance during feature extraction and object detection. Two scale space parameters define the extent of image smoothing (anisotropic diffusion iterations) and image simplification (scale of morphological levelings). Experimental results demonstrated the effectiveness of the developed scale space filtering for the enhancement and smoothing of hyperspectral remote sensing data and their advantage against watershed over-segmentation problems and edge detection.

• 한국통신학회논문지
• /
• 제15권12호
• /
• pp.1031-1043
• /
• 1990

비디오 코덱의 입력 또는 출력 영상에 내재하는 여러 종류의 영상잡음을 제어하고 최적으로 영상을 복원시키고자 코우절 영상 모델이 적용된 실시간 응용의 칼만 필터링 방법을 제안하였다. 화질의 개선도를 향상시키고자 처리화소선 간의 평균화와 지역 분산치에 의한 적응형 칼만 알고리즘을 제안하였고 그에 따른 잡음 제어와 영상 정보 복원 효과를 NMSE, LOGMSE 측정과 실험 결과에서 관측함으로써, 비디오 코덱의 전, 후처리 과정에서의 칼만 필터 적용 가능성을 제시하였다.

• 한국자동차공학회논문집
• /
• 제12권2호
• /
• pp.205-214
• /
• 2004

This paper presents design concepts, specifications and performances of a newly developed Black Box, the reconstruction analysis tool with the records, and results of validation tests. The Black Box can detect crash accidents automatically, and record the vehicle's motion and driver's maneuvers during a pre-defined time period before and after the accident. The items of the Black Box included the acceleration, yaw-rate, vehicle speed, engine RPM, braking application, steering and several digital inputs for recording driver's maneuvers. To detect the accident-related-crash, it is important to understand characteristics of the crash signal, which are much different from those of normal driving. Therefore, analytical considerations should be taken in designing pre-filtering circuits and selecting appropriate parameters for identifying crash accidents. And, it is necessary to select proper combination of motion sensors and design proper pre-filtering circuits in order to describe the vehicle's motion. The analysis algorithms were developed and implemented which can perform accurate detection of crash accidents, simulating pre-crash trajectories, and calculating parameters for reconstruction analysis of crash accidents. The developed Black Box was installed on passenger cars and several types of validation tests were conducted. Through the tests, the accuracy of the recorded data and usefulness of the analysis tool for reconstruction have been validated.

• 한국멀티미디어학회논문지
• /
• 제15권12호
• /
• pp.1409-1416
• /
• 2012

An image segmentation result depends on pre-processing steps such as contrast enhancement, edge detection, and smooth filtering etc. Especially medical images are low contrast and contain some noises. Therefore, the contrast enhancement and noise removal techniques are required in the pre-processing. In this study, we present an extension by a novel histogram equalization in which both local and global contrast is enhanced using neighborhood metrics. When checking neighborhood information, filters can simultaneously improve image quality. Most important is that original image information can be used for both global brightness preserving and local contrast enhancement, and image quality improvement filtering. Our experiments confirmed that the proposed method is more effective than other similar techniques reported previously.

• 한국군사과학기술학회지
• /
• 제20권4호
• /
• pp.482-490
• /
• 2017

The radar signal processing procedure is divided into the pre-processing such as frequency down converting, down sampling, pulse compression, and etc, and the post-processing such as doppler filtering, extracting target information, detecting, tracking, and etc. The former is generally designed using FPGA because the procedure is relatively simple even though there are large amounts of ADC data to organize very quickly. On the other hand, in general, the latter is parallel processed by multiple DSPs because of complexity, flexibility and real-time processing. This paper presents the radar signal processor design using FPGA which includes not only the pre-processing but also the post-processing such as doppler filtering, bore-sight error, NCI(Non-Coherent Integration), CFAR(Constant False Alarm Rate) and etc.