• 대한전자공학회논문지SP
• /
• 제37권5호
• /
• pp.42-53
• /
• 2000

전처리 필터링은 카메라로부터 들어오는 잡음을 제거하여 부호화 효율을 높여주기 때문에， 전처리 과정의 효과적인 구현은 동영상 압축에서 중요한 연구분야 중의 하나였다 본 논문에 근사화된 일반화 위너 필터링(approximated generalized Wiener filtering)과 이차원 DCT의 분해(factorization)를 바탕으로, 부호화기 내부에서 수행되는 효과적인 전처리 필터링 방법을 제안한다 제안한 전처리 필터링은 원 영상 블록 (original image block)과 움직임 보상된 차 영상 블록(motion-compensated error block)의 DCT계수들에 적절한 값들을 곱하는 것으로 수행된다 전처리 필터링이 동영상 압축기에 깊이 파묻혀 있지만, 전처리 과정으로 인한 연산량의 증가는 전체 부호화 과정에 비해 크지 않으며, 전통적인 블록 부호화 기법의 틀은 그대로 유지한다 간결한 구조와 연산에도 불구하고 제안한 방법은 잡음이 있는 동영상에 대해서 좋은 필터링 및 부호화 성능을 나타낸다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
• /
• pp.532-535
• /
• 2005

These days, many image processing techniques have been studied for effective image compression. Among those, 2D image filtering is widely used for 2D image processing. The 2D image filtering can be implemented by performing ID linear filtering separately in the direction of horizontal and vertical. Efficiency of image compression depends on what filtering method is used. Generally, circular convolution is widely used in the 2D image filtering for image processing. However it doesn't consider correlations at the region of image boundary, therefore filtering can not be performed effectively. To solve this problem. I proposed new convolution technique using Symmetric-Mirroring convolution, satisfying the 'alias-free' and 'error-free' requirement in the reconstructed image. This method could provide more effective performance than former compression methods. Because it used very high correlative data when performed at the boundary region. In this paper, pre-processing filtering in H.264 codec was adopted to analyze efficiency of proposed filtering technique, and the simulator developed by Matlab language was used to examine the performance of the proposed method.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.605-608
• /
• 1999

A conventional image coder, such as JPEG, requires not only DCT and quantization but also additional pre-filtering under noisy environment. Since the pre-filtering removes camera noise and improves coding efficiency dramatically, its efficient implementation has been an important issue. Based on well-known noise removal techniques in image processing fields, this paper introduces an efficient scheme by adapting a noise removal procedure to block-based image coders. By using two-dimensional DCT factorization, the proposed image coder has only a modified DCT and a VLC, and performs pre-filtering and quantization simultaneously in the modified DCT operation.

• International Journal of Control, Automation, and Systems
• /
• 제6권2호
• /
• pp.204-213
• /
• 2008

In this paper, we present the practical application of an Unscented Kalman Filter (UKF) for an Indoor Mobile Localization System using ultrasonic sensors. It is true that many kinds of localization techniques have been researched for several years in order to contribute to the realization of a ubiquitous system; particularly, such a ubiquitous system needs a high degree of accuracy to be practical and efficient. Unfortunately, a number of localization systems for indoor space do not have sufficient accuracy to establish any special task such as precise position control of a moving target even though they require comparatively high developmental cost. Therefore, we developed an Indoor Mobile Localization System having high localization performance; specifically, the Unscented Kalman Filter is applied for improving the localization accuracy. In addition, we also present the additive filter named 'Pre-filtering' to compensate the performance of the estimation algorithm. Pre-filtering has been developed to overcome negative effects from unexpected external noise so that localization through the Unscented Kalman Filter has come to be stable. Moreover, we tried to demonstrate the performance comparison of the Unscented Kalman Filter and another estimation algorithm, such as the Unscented Particle Filter (UPF), through simulation for our system.

• Journal of applied mathematics & informatics
• /
• 제28권1_2호
• /
• pp.439-450
• /
• 2010

In this paper, we propose a new idea to evaluate the prediction accuracy of user's preference generated by memory-based collaborative filtering algorithm before prediction process in the recommender system. Our analysis results show the possibility of a pre-evaluation before the prediction process of users' preference of item's transaction on the web. Classification functions proposed in this study generate a user's rating pattern under certain conditions. In this research, we test whether classification functions select users who have lower prediction or higher prediction performance under collaborative filtering recommendation approach. The statistical test results will be based on the differences of the prediction accuracy of each user group which are classified by classification functions using the generative probability of specific rating. The characteristics of rating patterns of classified users will also be presented.

• 인터넷정보학회논문지
• /
• 제23권1호
• /
• pp.125-134
• /
• 2022

정보 통신 및 인공지능 기술의 발전은 우리 군의 지휘통제체계의 지능화를 요구하며, 이를 달성하기 위해 다양한 시도가 이루어지고 있다. 본 논문은 특히, 지휘통제 워크플로우에서 활용 가능한 정보의 양이 폭발적으로 증가함에 따라 지휘통제체계 사용자에게 제공되는 정보 중 수행 업무에 가장 핵심적인 정보를 제공할 수 있는 협업 필터링(Collaborative Filtering, CF) 및 추천 시스템(Recommendation System, RS)에 주목한다. 군 지휘통제체계에서 정보의 필터링을 수행하는 RS는 가장 우선 설명 가능한 추천을 수행하여야 하며, 그 다음 지휘관들이 임무를 수행하는 다양한 상황을 고려한 추천이 수행되어야 한다. 본 논문에서는 지휘통제 워크플로우를 지원하기 위하여 정보를 선택적으로 추천하는 contextual pre-filtering CARS 프레임워크를 제안한다. 제안된 프레임워크는 1) 지휘결심자의 상황 및 관계에 기반하여 데이터를 사전에 필터링하는 contextual pre-filtering, 2) CF의 취약한 데이터 희소성 문제를 극복하기 위한 피쳐 선택, 3) 피쳐 간의 디스턴스를 사용자의 유사도 산출에 활용한 CF, 및 4) 사용자의 선호를 반영하기 위한 규칙 기반 포스트 필터링의 4 단계로 구성되어 있다. 본 연구의 우수성을 평가하기 위해서 상용 수준의 실험 데이터셋 2종에 대해 기존 CF 방법의 다양한 디스턴스 방법을 적용하여 비교 실험하였다. 비교 실험 결과 제안된 프레임워크가 3가지 평가지표(MAE, MSE, MSLE) 측면에서 우수함을 나타내었다.

• 한국CDE학회논문집
• /
• 제17권2호
• /
• pp.97-110
• /
• 2012

High performance sensors and modern data logging technology with real-time telemetry facilitate system fault diagnosis in a very precise manner. Fault detection, isolation and identification in fault diagnosis systems are typical steps to analyze the root cause of failures. This systematic failure analysis provides not only useful clues to rectify the abnormal behaviors of a system, but also key information to redesign the current system for retrofit. The main barriers to effective failure analysis are: (i) the gathered data (event) logs are too large in general, and further (ii) they usually contain noise and redundant data that make precise analysis difficult. This paper therefore applies suitable pre-processing techniques to data reduction and feature extraction, and then converts the reduced data log into a new format of event sequence information. Finally the event sequence information is decoded to investigate the correlation between specific event patterns and various system faults. The efficiency of the developed pre-filtering procedure is examined with a terminal box data log of a marine diesel engine.

• Journal of the Korean Data and Information Science Society
• /
• 제18권3호
• /
• pp.619-628
• /
• 2007

This study is devoted to suggesting the norm of detection abnormal users who are inferior to the other users in the recommender system compared with estimation accuracy. To select the abnormal users, we propose the pre-filtering method by using the preference ratings to the item rated by users. In this study, the experimental result shows the possibility of detecting the abnormal users before the process of preference estimation through the prediction algorithm. And It will be possible to improve the performance of the recommender system by using this detecting norm.

• 한국통신학회논문지
• /
• 제31권3A호
• /
• pp.328-336
• /
• 2006

지상파 디지털 TV 방송 서비스를 위해 송신기에서는 인접 채널에 미치는 영향을 최소화하기 위해서 FCC에서 규정한 전송 신호에 대한 emission mask를 만족하도록 채널 필터를 사용한다. 이러한 채널 필터는 군지연과 크기 왜곡을 야기하는데, 이를 보상하기 위해서 전치등화기를 사용한다. 기존의 전치등화기는 모두 FIR 필터링에 근간을 두고 있었지만, 본 논문에서는 FIR 필터링을 사용하는 전치등화 방법을 제안한다. IIR 필터는 pole-zero 모델링 특성이 있어서 기존 FIR 필터를 이용하는 방법에 비해서 신호 대 잡음비를 향상시킬 수 있고 채별 필터의 왜곡뿐만 아니라 DTV 송신기 내에 존재하는 다양한 선형적인 계곡까지 보상할 수 있는 장점이 있다. 시뮬레이션을 통하여 제안된 IIR 전치등화기가 FIR 전치등화기에 비해서 잔류 평균 자승 오차 측면에서 매우 우수함을 보인다.

• International Journal of Aeronautical and Space Sciences
• /
• 제12권4호
• /
• pp.371-378
• /
• 2011

In this paper, the wavelet denoising techniques using thresholding method are applied to the low cost micro electromechanical system (MEMS)-global positioning system(GPS) integrated system. This was done to improve the navigation performance. The low cost MEMS signals can be distorted with conventional pre-filtering method such as low-pass filtering method. However, wavelet denoising techniques using thresholding method do not distort the rapidly-changing signals. They can reduce the signal noise. This paper verified the improvement of the navigation performance compared to the conventional pre-filtering by simulation and experiment.