• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.3
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• pp.217-226
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• 1986

A method on the hardware implementation of the Multi-channel FIR digital filter using Digital Quarter Square Multiplication(DQSM) algorithm is proposed. This paper describes that ROM requirement can be reduced by using the double precision algorithm and the absolute value circuit, and also execution speed can be improved by reducing logic level steps of absolute value circuit. The frequency response of the four channel FIR digital filter implemented by the above method is quite agreeable with the frequency response simulated by Remez excahange algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.55-63
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• 2013

Digital retrodirective antenna system is easy to modify and upgrade because it can control the phase information of the output signal toward opposite direction to input signal without a priori knowledge of the arrival direction. Due to this advantage, it is possible to do fast beam tracking. Especially, we need to design the digital PLL performance for the digital retrodirective array antenna system. So, in this paper the settling time of phase estimator and BER performance of retrodirective antenna system are investigated according to design of filter in digital PLL. When QAM signal is used for 1 Mbps with $30^{\circ}$ of phase delay, simulation results show that digital phase conjugation technique has better BER performance by about 1 dB than non-phase conjugation system when digital filter is stable. If not, the system can't estimate the exact phase because of oscillation of filter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.30-35
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• 2017

In this study, we measured the natural frequencies of aluminum honeycomb sandwich beams using digital image correlation technique. The vibration images were captured using two high speed digital cameras and the images were converted to displacements by the digital image correlation technique. Displacement data in time domain were tranformed to frequency domain data by fast Fourier transform software. To reduce noise invoked by random exitation, a spectrum averaging technique and Savitsky-Golay digital filter were adopted. A conventional vibration measurement using an accelerometer and a finite element analysis were performed to compare the results by high speed digital camera measurement method. In conclusion, new method using high speed digital cameras and digital image correlation technique can measure the vibration of beam structures and can be applied to bio-structures where sensors cannot be attached.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.955_956
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• 2009

계통의 전력품질을 향상시키기 위해서는 비선형부하로 인해 발생되는 무효전력을 보상해야 한다. 이러한 무효전력을 보상하는 알고리즘에서 지령치를 생성하기 위해 평균전력 또는 순시전력을 이용한다. 평균전력을 이용하는 방법은 매 한주기마다 평균전력을 계산하여 지령치를 생성하는 방법으로 필연적으로 지연시간이 발생하게 된다. 이에 반해 순시전력을 이용하는 방법은 매 스위칭 순간에 무효전력을 보상할 수 있어 시스템 응답속도가 빠른 장점을 가진다. 또한 유효전력과 무효전력을 계산하기 위해 디지털 필터를 이용하게 되면 회로구성이 간편하고 제어가 용이한 장점이 있다. 본 논문에서는 계통의 전력품질을 개선시키기 위해 1개의 LPF(Low Pass Filter)와 2개의 곱셈블럭으로 구성되는 디지털 필터를 사용하였다. 이의 유용성을 확인하기 위해 단상 능동전력 필터(active power filter)에 적용하여 시뮬레이션을 수행하였다.

• Journal of Digital Contents Society
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• v.13 no.3
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• pp.271-278
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• 2012

Recently, infrared (IR)-based depth sensors have proliferated as consumer electronics thanks to decreased price, which led to various applications including gesture recognition in television virtual studios. However, the depth sensors fail to capture depth information correctly under strong light conditions emitting infrared light which are very common in television studios. This paper analyzes the mechanism of such interference between the depth sensors relying on certain IR frequencies and infrared light emitting sources, and provides methods to get correct depth information by applying filters. Also, it describes experiment methods and presents the results of applying multiple combinations of filters with different cut-off frequencies. Finally, it proves that the interference due to IR can be filtered out using proposed filtering method practically by experiment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.400-403
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• 2010

본 논문에서는 디지털 카메라의 자동초점 속도를 향상시키는 새로운 기법을 제안한다. 제안된 방식은 위상차 검출 방식에서 사용되는 추가적인 자동초점 모듈을 장착하지 않으면서도 빠르게 초점이 맞는 위치의 거리와 방향을 계산할 수 있는데, 이는 이중 분할 조리개를 이용하여 위상차가 발생하도록 하고, 컬러 필터를 이용하여 분리함으로써 소프트웨어 영상 처리만으로 위상차를 측정하여 정확한 초점 위치를 찾을 수 있기 때문이다. 이중 분할 조리개에 의해서 발생한 컬러 영상 채널 간의 상이한 정도를 측정하기 위하여 초점이 맞는 정도를 수치화 할 수 있는 유사도 측정 기준을 제시하는데, 이 기준으로 측정된 유사도를 비교함으로써 불일치 정도를 추출하며 정확한 초점을 잡기 위한 거리와 방향을 계산한다. 실험에서는 상용 디지털 카메라를 개조한 프로토 타입에서 취득한 영상을 사용하여 제안한 방식의 유효성을 검증하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.380-383
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• 2010

본 논문에서는 다시점 카메라를 기반으로 홀로그램 영상을 재생하는 기술을 제안한다. 본 논문에서는 다시점 카메라를 이용해 획득한 발레영상을 사용하여 깊이정보에서 관심객체만을 추출하였다. 추출한 관심객체의 홀로그램 복원화질을 향상시키기 위해 본 논문에서 제안한 함수를 적용하였다. 필터링된 관심객체의 깊이정보와 CGH(Computer-Generated Hologram) 기법을 이용하여 디지털 홀로그램을 생성하였다. 이 디지털 홀로그램을 PC 시뮬레이션을 통해 홀로그램 영상으로 복원한 후 제안한 기법의 적용결과를 주관적인 화질평가를 통해 검증하였다.

• Annual Conference of KIPS
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• 2015.10a
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• pp.878-879
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• 2015

어플리케이션 구동 시에 화면에 표시되는 데이터는 보안 알고리즘이 적용되지 않은 채로 사용자 및 악의적인 해커들에게 노출된다. 본 논문에서는 악의적인 사용자가 화면을 캡쳐하여 이미지 파일로 저장하거나 디지털카메라로 화면에 노출된 정보의 사진을 찍었을 때 중요 데이터가 유출되지 않도록 화면 출력 이미지를 디지털 영상 처리 기법을 이용하여 변조한다. 사용자가 육안으로 볼 때에는 데이터를 식별할 수 있도록 화면 주사율에 맞추어 변조된 영상에 대한 보완 영상을 번걸아 출력한다.

• Journal of Digital Convergence
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• v.11 no.2
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• pp.235-242
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• 2013

Reputation systems aggregate users' feedback after the completion of a transaction and compute the "reputation" of products, services, or providers, which can assist other users in decision-making in the future. With the rapid growth of online e-Learning content providing services, a suitable reputation system for more credible e-Learning content delivery has become important and is essential if educational content providers are to remain competitive. Most existing reputation systems focus on generating ratings only for user reputation; they fail to consider the reputations of products or services(item reputation). However, it is essential for B2C e-Learning services to have a reliable reputation rating mechanism for items since they offer guidance for decision-making by presenting the ranks or ratings of e-Learning content items. To overcome this problem, we propose a novel collaborative filtering based reputation rating method. Collaborative filtering, one of the most successful recommendation methods, can be used to improve a reputation system. In this method, dual information sources are formed with groups of co-oriented users and expert users and to adapt it to the reputation rating mechanism. We have evaluated its performance experimentally by comparing various reputation systems.

• The Journal of the Acoustical Society of Korea
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• v.25 no.6
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• pp.291-297
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• 2006

This paper proposes a new Digital Reverberator that models Analog Helical Coil Spring Reverberator for guitar amplifiers. While the conventional digital reverberators are proposed to provide better sound field mainly based on room acoustics, no algorithm or analysis of digital reverberators those model Helical Coil Spring Reverberator was proposed. Considering the fact that approximately $70{\sim}80$ percent of guitar amplifiers are still with Helical Coil Spring Reverberator, research was performed based not on Room Acoustics but on Helical Coil Spring Reverberator itself as an effector. After performing simulations with proposed algorithm, it was confirmed that the Digital Reverberator by proposed algorithm provides perceptually equivalent response to the conventional Analog Helical Coil Spring Reverberators.