• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.312-314
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• 2007

본 논문은 단상하프브릿지 구조를 갖는 계통연계형 전압형 PWM 인버터를 위한 필터설계를 목적으로 한다. 단상하프브릿지 전압형 PWM 인버터의 교류출력단 전압과 계통전압의 관계를 분석하여 필터인덕터에 흐르는 스위칭리플전류의 크기를 정성적 및 정량적으로 구하였다. 이러한 분석을 기초로 하여 계통주입전류의 기본파성분에 대한 스위칭리플전류의 비율을 평가함수로 하는 필터인덕터의 설계법을 제시하였다. 제안된 설계방법을 실험을 통하여 검증한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.54-61
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• 2023

With the development of IoT technologies and artificial intelligent, diverse digital image equipments are being used in industrial sites. Because image data can be easily damaged by noise while it's obtained with a camera or a sensor and the damaged image has a bad effect on the process of image processing, noise removal is being demanded as preprocessing. In this thesis, for the restoration of image damaged by the noise of random impulse, a switching filter algorithm based on noise estimation was suggested. With the proposed algorithm, noise estimation and error distraction were carried out according to the similarity of the pixel values in the local mask of the image, and a filter was chosen and switched depending on the ratio of noise existing in the local mask. Simulations were conducted to analyze the noise removal performance of the proposed algorithm, and as a result of magnified image and PSNR comparison, it showed superior performance compared to the existing method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.253-255
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• 2022

Thanks to the 4th industrial revolution and the development of various communication media, technologies such as artificial intelligence and automation are being grafted into industrial sites in various fields, and accordingly, the importance of data processing is increasing. Image noise removal is a pre-processing process for image processing, and is mainly used in fields requiring high-level image processing technology. Various studies have been conducted to remove noise, but various problems arise in the process of noise removal, such as image detail preservation, texture restoration, and noise removal in a special area. In this paper, we propose a switching mask filter based on the noise intensity to preserve the detailed image information during the impulse noise removal process. The proposed filter algorithm obtains the final output by switching to the extended mask when it is determined that the density is higher than the reference value when noise is determined in the area designated as the filtering mask. Simulation was conducted to evaluate the performance of the proposed algorithm, and the performance was analyzed compared to the existing method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.645-651
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• 2021

With the advent of the Fourth Industrial Revolution, modern society uses a diverse pool of devices. In this context, there is increasing interest in removing various kinds of noise arising in data transmission. However, it is difficult to restore image that damaged by mixed noise, and a digital filter that effectively restores an image according to the characteristics of the noise is required. In this paper, we propose a digital switching filter algorithm to remove mixed noise generated during digital image transmission. The proposed algorithm switches the filtering process through noise judgment and reconstructs the image using fuzzy weights and combined weights based on the pixel values inside the mask. To evaluate the proposed algorithm, we compared it with existing filter algorithms through simulation. Filtering results were expanded and compared for visual evaluation, and PSNR comparison was used for quantitative evaluation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.121-123
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• 2021

Image processing is being used in various forms in important fields of the 4th industrial revolution, such as artificial intelligence, smart factories, and the IoT industry. In particular, in systems that require data processing such as object tracking, medical images, and object recognition, noise removal is used as a preprocessing step, but the existing algorithm has a drawback in that blurring occurs in the filtering process. Therefore, in this paper, we propose a filter algorithm using switching fuzzy weights. The proposed algorithm switches the fuzzy function by dividing the low-frequency region and the high-frequency region by the standard deviation of the filtering mask, and obtains the final output according to the fuzzy weight. The proposed algorithm showed improved results compared to the existing method, and showed excellent characteristics in the region where the high-frequency component is strong.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.176-178
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• 2008

최근 전력전자 기기와 같은 비선형 부하의 증가로 계통에서 고조파 발생 가능성은 점점 높아지는 추세이다 이러한 계통의 고조파는 부하 설비 중 누전차단기 오동작 및 과부하 등의 원인이 되므로 전기설비 안전 측면에서 중요하게 다루어질 필요가 있다. 고조파에 대한 해결책으로는 수동필터 및 능동전력필터를 들 수 있는데 본 연구에서는 기존의 3상 풀브리지 스위칭 회로를 이용한 능동필터에 비해 안정성 및 대용량 시스템 구성에 유리한 모듈형 능동 전력 필터를 제안하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.38-39
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• 2011

본 논문은 PWM DC-AC 인버터에서의 AC 필터 인덕터 코아 손실 계산을 위한 간단한 방법을 제시한다. 코아 손실 분석을 위해서 AC 필터 인덕터로 아몰퍼스 C-Core (AMCC-320)를 선택하였다. 단상하프브릿지 전압형 인버터와 간이 열량계를 이용하여 코아 손실을 측정하고 제시한 방법을 검증하였다. 기본적으로 인버터 스위칭은 SPWM 방법을 사용하였으며, 스위칭 주파수와 모듈레이션 인덱스를 가변하면서 실제 제작한 간이 열량계로 코아 손실을 측정하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.429-430
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• 2012

본 논문에서는 LED 구동용 전원장치의 필터커패시터와 변압기 권선비에 따른 MOSFET의 전압 정격 및 스위칭 손실 특성 등을 다루었다. 스위칭 손실을 최소화 하려면 변압기 권선비를 최적화할 필요가 있다. 또한 필터커패시터 값이 MOSFET의 전압정격에 영향을 미치므로 이를 고려한 설계가 필요함을 확인하였다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.189-191
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• 2019

본 논문에서는 작은 필터인덕턴스를 갖는 새로운 소프트스위칭 3레벨 Flying Capacitor 컨버터를 제안한다. 제안한 컨버터는 보조 인덕터 La와 보조 커패시터 Ca로 인해 모든 스위치의 ZVS 턴 온을 성취하여 높은 효율을 달성할 수 있고, Flying capacitor로 인해 필터 인덕터에 걸리는 전압이 감소하며 스위치간의 위상차로 인해 동작주파수가 2배가 되어 필터 인덕턴스를 줄일 수 있다. 또한 3레벨 구조로써 800V~1000V의 고전압 응용에서 600V의 Si-MOSFET을 사용할 수 있어 도통손실을 줄일 수 있다. 제안하는 컨버터의 동작원리, 비교분석, 인터리빙 효과를 제시하고 시작품을 통해 본 논문의 타당성 및 성능을 검증하였다.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.28-32
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• 2017

In this paper, a quasi-resonant PWM converter, which is controlled by constant frequency, has been suggested. As quasi-resonant converter, the switches of the suggested converter has soft switching characteristics, which can operate to high frequency with high efficiency. Comparing with varied controlled frequency of quasi-resonant converter for controlling output voltage, the suggested converter has advantages which optimize filter and EMI filter design at constant switching frequency. The converter has been analyzed by switch mode analysis which verified soft switching operation. Also, the PWM operation and characteristics of the converter are verified by simulation and experiment of 100 kHz DC-DC converter.