• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2319-2328
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• 2018

This paper introduces a control method for a transformerless MMC-HVDC system. The proposed method can effectively control the grid currents of the MMC-HVDC system under unbalanced grid conditions such as a single line-to-ground fault. The proposed method controls the currents of the positive sequence component and the negative sequence component without separating algorithms. Therefore, complicated calculations for extracting the positive sequence and the negative sequence component are not required. In addition, a control method to regulate a zero sequence component current under unbalanced grid conditions in the transformerless MMC-HVDC system is also proposed. The validity of the proposed method is verified through PSCAD/EMTDC simulation.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.537-543
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• 1999

While there are to estimating design discharge , we are in trouble with how to separate area, Because discharges will be different depending on the shape of area even though there are same size of area . This study is for a reasonable presentation of design discharge method where there are changing characteristcs of area with SCS and Clark theory by sung HEC-1 Model. While we were Estimating desgin discharge with separating area in a relation to Time of Concentration(Tc) with SCS , Clark method, we found that if there are no variation of Tc the value of a discharge is not changed where shapes of area are different though. And from the result of analysis with SCS and Clark method, we ascertained that discharge by the SCS method was more bigger than that of the Clark where Area is less than 100ha. On the other hand, Clark method is more bigger in the more 1000ha.

• 한국정보기술학회 영문논문지
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• 제10권2호
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• pp.125-138
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• 2020

Due to the development of camera technology, the cost of producing time-lapse video has been reduced, and time-lapse videos are being applied in many fields. Time-lapse video is created using images obtained by shooting for a long time at long intervals. In this paper, we propose a method to improve the quality of time-lapse videos monitoring the changes in plants. Considering the characteristics of time-lapse video, we propose a method of separating the desired and unnecessary objects and removing unnecessary elements. The characteristic of time-lapse videos that we have noticed is that unnecessary elements appear intermittently in the captured images. In the proposed method, noises are removed by applying a codebook background modeling algorithm to use this characteristic. Experimental results show that the proposed method is simple and accurate to find and remove unnecessary elements in time-lapse videos.

• Journal of Positioning, Navigation, and Timing
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• 제2권1호
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• pp.67-74
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• 2013

In this study, a remote controller was designed using localization technique. The designed remote controller system consists of infrared transmit/receive module for time synchronization, ultrasonic transmit/receive module for measuring the TOA value, and micro-controller for processing the measured data value. For the position estimation method of remote controller, the Savarese method was used which does not have a problem of diverging solution depending on initial value. The noise included in the measured value was removed by separating the signal and noise with the use of EMD method which is the non-stationary signal analysis technique. The designed system was tested by constructing a simulation environment, and the improvement of accuracy and precision for the application of EMD method was examined.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.969-974
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• 2007

In this paper, a beamforming technique is introduced to measure the acoustic impedance at both normal and oblique incidence in a free field. The acoustic impedance is obtained by separating incident and reflected signals using the adaptive nulling method which is one of the various beamforming algorithms. To obtain better results, pressure vector commonly used in array signal processing is replaced with the transfer function vector between each microphone and the white Gaussian noise is suppressed by a wavelet shrinkage technique. The experiments conducted in a semi-anechoic room show that the proposed method is efficient and accurate in measuring the acoustic impedance of sound absorbing materials under a free field condition.

• 한국위성정보통신학회논문지
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• 제7권3호
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• pp.140-144
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• 2012

비디오 감시시스템의 영상 기록 및 검색을 위한 고전적 방법은 감시 영상만이 가지는 특징, 즉 감시영상에서 불필요한 배경 영역과 감시 대상을 목적으로 하는 물체 영역을 분리하여 저장하는 시스템을 갖추지 않으므로 감시영상의 저장 및 검색을 하는데 있어서 많은 저장 용량이 요구되기 때문에 매우 비효율적이다. 본 논문에서 제안한 감시 영상 시스템의 기록 및 검색 방법은 비효율적 요소를 해결한 시간별 장소별로 데이터베이스를 활용하여 손쉽게 검색하는 비디오 감시 시스템으로서 기존의 방법에 비해 더욱 효율적인 감시영상의 검색을 가능하게 한다.

• Transactions on Electrical and Electronic Materials
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• 제8권3호
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• pp.143-146
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• 2007

Polymer insulators are used widely in variable fields for high voltage insulation and separating people from high voltage charging parts for safety and also supporting overhead power line in electric railway. But it may be broken down by tracking path resulting from continuous surface discharge. This paper has investigated synthetically both the characteristics of electrical aging using precision CT(current transformer) and the thermal aging using thermography method. Electrical aging was analyzed for time-frequency region and thermal aging was illustrated by image processing method. This synthetic method may be an appropriate one to evaluate the surface degradation of polymer insulator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.31-34
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• 2003

In this paper, we describe a method for separating text lines in handwritten Korean address images. The most remarkable feature of the proposed method is to use a modified projection technique. named a partial projection technique. A projection based text line separation method which projects the whole address image in horizontal direction to find split points for text line separation cannot avoid failing separation in case of images with a little skew or overlap between vertically neighboring text lines. To overcome this problem, we have introduced a partial projection technique which splits an address image into a few partial address images to be equal width and then project them each horizontally. The experiment done with 989 handwritten Korean address images extracted from live mails shows the superiority of the proposed method. The correct text-line separation rate fir the testing images was about 91.5％.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.131-138
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• 2014

This paper is on a stereo acoustic echo canceller with the blind signal separation for post processing. The convergence speed of the stereo acoustic echo canceller is deteriorated due to mixing two residual signals which are update signals of each echo canceller. To solve this problem, we are to use the blind signal separation(BSS) method separating the mixed signals after the echo cancellers. The blind signal separation method can extracts the source signals by means of the iterative computations with two input signals. We had verified performances of the proposed acoustic echo canceller for stereo through simulations. The results of simulations show that the acoustic echo canceller for stereo using this algorithm operates stably without divergence in the normal state. And, when the speech signals were inputted, this echo canceller achieved about 2dB higher ERLE with the BSS post processing method than without this method. This stereo echo canceller showed the best performance in the case of inputting the real voice signal.

• 정보처리학회논문지D
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• 제16D권6호
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• pp.927-934
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• 2009

본 논문에서는 UML CASE 도구 프레임워크 구축에 이용할 수 있는 공통성 및 가변성 분석 기법을 제안하고자 한다. 공통성 및 가변성 분석은 동일 도메인에서 어플리케이션 특성에 따라 변할 수 있는 영역과 변하지 않는 영역을 구분함으로써 확장과 재사용성을 향상시킬 수 있는 방법이다. 공통성 및 가변성 분석 기법으로 클래스에 기반한 분류기법을 제안하였으며, 이를 명시적으로 나타낼 수 있는 표기법을 제시하였다. 또한 분석 기법을 바탕으로 프레임워크를 구현하였으며, 결함 제거 효율성을 이용해 분석 기법의 검증을 수행하였다.