• Journal of Multimedia Information System
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• v.8 no.4
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• pp.211-220
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• 2021

The process of inspecting SMDs on the PCB boards improves the product quality, performance and reduces frequent issues in this field. However, undesirable scenarios such as assembly failure and device breakdown can occur sometime during the assembly process and result in costly losses and time-consuming. The detection of these components with a model based on deep learning may be effective to reduce some errors during the inspection in the manufacturing process. In this paper, YOLO models were used due to their high speed and good accuracy in classification and target detection. A SMD detection and classification method using YOLO networks based on robust data preprocessing and augmentation techniques to deal with various types of variation such as illumination and geometric changes is proposed. For 9 different components of data provided from a PCB manufacturer company, the experiment results show that YOLOv4 is better with fast detection and classification than YOLOv3.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.252-255
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• 2000

In this paper, a fast pseudo-noise (PN) code acquisition with novel adaptive architecture is presented in direct-sequence spread- spectrum (DS-SS) systems. Since an existing acquisition system has a fixed correlation tap size and threshold value, this system cannot adapt to various mobile communication environments and results in a low detection probability or a high false alarm rate and long acquisition time. Therefore, if a correlation tap size and a threshold value can be controlled adaptively according to received signals, problems of ail existing system will be solved. The system parameter varies adaptively by using constant false alarm rate (CFAR) algorithm well known in a field of detection and proposed signal-to-noise ratio (SNR) measurement system. By deriving formulas of the proposed system, the performance is analyzed.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2141-2144
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• 2009

• Journal of Power Electronics
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• v.18 no.5
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• pp.1608-1617
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• 2018

The rapid and correct isolation of faulty submodules (SMs) is of great importance for improving the reliability of modular multilevel converters (MMCs). Therefore, a fast diagnosis method containing fault detection and fault location determination was presented in this paper. An improved incremental predictive model of arm current was proposed to detect failures, and the multi-step prediction method was used to eliminate the negative impact of disturbances. Moreover, a control method was proposed to strengthen the fault characteristics to rapidly locate faulty arms and faulty SMs by detecting the variation rate of the SM capacitor voltage. The proposed method can rapidly and easily locate faulty SMs under different load conditions without the need for additional sensors. The experimental results have validated the effectiveness of the proposed method by using a single-phase MMC with four SMs per arm.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.4
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• pp.406-414
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• 1997

A real-time inspection system is developed using line scan cameras. Several improved algorithms are proposed for real-time detection of defects in this automated inspection system. The major improved algorithms include the preprocessing, the threshold decision, and the clustering algorithms. The preprocessing algorithms are for exact binarization and the threshold decision algorithm is for fast detection of defects in 1-D binary images. The clustering algorithm is also developed for fast classifying of the defects. The system is applied to PCBs(Printed Circuit Boards) inspection. The typical defects in PCBs are pits, dent, wrinkle, scratch, and black spots. The results show that most defects are detected and classified successfully.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.259-262
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• 2012

In this paper, we propose a new fast algorithm for effective scene change detection. The proposed algorithm exploits Otsu threshold matching technique, which was proposed earlier. In this method, the current and the reference frames are divided into square blocks of particular size. After doing so, the pixel histogram of each block is generated. According to Otsu method, every histogram distribution is assumed to be bimodal, i.e. pixel distribution can be divided into two groups, based on within-group variance value. The pixel value that minimizes the within-group variance is said to be Otsu threshold. After Otsu threshold is found, the same procedure is performed at the reference frame. If the difference between Otsu threshold of a block in the current frame and co-located block in the reference frame is larger than predefined threshold, then a scene change between those two blocks is detected.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1997.11a
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• pp.417-433
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• 1997

A real-time operating system has focused primary on techniques to minimize processing time, with a secondary emphasis on system reliability issues. Conversely, fault-tolerant system has concentrated on using recourse and information redundancy to maximize the availability and reliability of the system, with a lesser emphasis on performance. We have developed a fault-tolerant and real-time operations system which support a powerful concurrent runtime environment under the above requirements. In this paper, we present an overview of real-time systems, design and implementation of a duplex architecture using advanced concepts and technologies such as fast " fault detection", "fault isolation" and "fault recovery" Because the duplex architecture has two dentical hardware elements and has several recovery steps and hierarchy to facilitate a fast recovery which must be proceeded by a prompt fault detection and isolation. Thus it makes possible to minimize the overhead of the systems including hardware and software and guarantee the service continuity of he systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.30-35
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• 2010

As of today, Frequency Hopping techniques are widely used for over-channel interference and anti-jamming communication systems. In this paper, analysis the performance of robustness on the focus of some general jamming channel. In FH/SS systems, usually SFH(Slow Frequency Hopping) and FFH(Fast Frequency Hopping) are took up on many special communication systems, the SFH, FFH are also combined with a channel diversity algorithm likes NED(Normalized Envelop Detection), EGC(Equal Gain Combines) and Clipped Combines to overcome jammer's attack. This paper propose Adaptive-NED and shows A-NED will be worked well than the others in the some general jamming environments.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.95-99
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• 2011

Digital forensics is the emerging research field for determining digital forgeries. Key issues of the tampered images are to solve the problems for detecting the interpolation factor and the tampered regions. This paper describes a method to detect the interpolation factors and the forged maps using the differential method and fast Fourier transform(FFT) along the horizontal, vertical, and diagonal direction, respectively from digital filtered tampered images. The detection map can be used to find out interpolated regions from the tempered image. Experimental results demonstrate the proposed algorithm proves effective on several filtering images by adobe $Photoshop^{TM}$ and show a ratio of detecting the interpolated regions and factors from digital filtered composite images.

• Journal of Korea Multimedia Society
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• v.14 no.5
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• pp.622-631
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• 2011

Corners play an important role in describing object features for pattern recognition and identification. This paper proposed a fast and adaptive corner detector in both coarse and fine scale, followed by the framework of the curvature scale space (CSS). An adaptive curvature threshold and evaluating of angles of corner candidates are added to original CSS to remove round corners and false corners in the detecting process. The efficiency of proposed method is compared to other popular detectors in both accuracy criteria, stability and time consuming. Results illustrate that the proposed method performs extremely surpass in both areas.