• 정보관리학회지
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• 제26권3호
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• pp.169-188
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• 2009

본 연구는 비디오의 오디오 정보를 추출하여 자동으로 요약하는 알고리즘을 설계하고, 제안된 알고리즘에 의해서 구성한 오디오 요약의 품질을 평가하여 효율적인 비디오 요약의 구현 방안을 제안하였다. 구체적인 연구 결과를 살펴보면 다음과 같다. 먼저, 제안 오디오 요약의 품질이 위치 기반 오디오 요약의 품질 보다 내재적 평가에서 더 우수하게 나타났다. 이용자 평가(외재적 평가)의 요약문 정확도에서는 제안 요약문이 위치 기반 요약문 보다 더 우수한 것으로 나타났지만, 항목 선택에서는 이 두 요약문간의 성능 차이는 없는 것으로 나타났다. 이외에 비디오 브라우징을 위한 오디오 요약에 대한 이용자 만족도를 조사하였다. 끝으로 이러한 조사 결과를 기초로 하여 제안된 오디오 요약 기법을 인터넷이나 디지털 도서관에 활용하는 방안들을 제시하였다.

• 한국정보통신학회논문지
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• 제11권12호
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• pp.2382-2390
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• 2007

본 논문에서는 비선형 앰프를 선형화 하는 다항식에 기반한 사전왜곡 알고리즘을 제안한다. 제안된 방식은 기존의 다항식 기반 방식과는 다르게 사후왜곡기의 도움 없이 직접 학습 방식으로 사전왜곡 계수를 추정한다. 먼저 앰프의 특성이 부분 선형으로 가정하여 알고리즘이 유도되고, 다음에 이 알고리즘을 앰프에 대한 어떠한 가정이 필요없는 구조로 변경한다. 제안된 사전왜곡기는 복소 계수를 가지는 다항식으로 구성되며 다항식의 계수는 RLS(recursive least squares)에 기반하여 찾게 된다. 컴퓨터 모의실험에 의하면 제안된 직접방식의 알고리즘이 기존의 간접 학습 방식에 비해 앰프의 초기 계수나 포화 영역에서 강인한 특성을 보인다.

• Journal of Power Electronics
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• 제19권6호
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• pp.1496-1504
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• 2019

This paper proposes a new THD reduction algorithm for modular multilevel converters (MMCs) with offset voltage injection operated in nearest level modulation (NLM). High voltage direct current (HVDC) is actively introduced to the grid connection of offshore wind powers, and this paper deals with a voltage generation technique with an MMC for wind power generation. In the proposed method, third harmonic voltage is added for reducing the THD. The third harmonic voltage is adjusted so that each of the pole voltage magnitudes maintains a constant value with a maximum number of (N+1) levels, where N is the number of sub-modules per arm. By using the proposed method, the THD of the output voltage is mitigated without increasing the switching frequency. In addition, the proposed method has advantageous characteristics such as simple implementation. As a part of this study, this paper compares the THD results of the conventional method and the proposed method with offset voltage injection to reduce the THD. In this paper, simulations have been carried out to verify the effectiveness of the proposed scheme, and the proposed method is implemented by a HILS (Hardware in the Loop Simulation) system. The obtained results show agreement with the simulation results. It is confirmed that the new scheme achieved the maximum level output voltage and improved the THD quality.

• Smart Structures and Systems
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• 제32권2호
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• pp.123-133
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• 2023

This paper proposes a thermography-based coating thickness estimation method for steel structures using model-agnostic meta-learning. In the proposed method, a halogen lamp generates heat energy on the coating surface of a steel structure, and the resulting heat responses are measured using an infrared (IR) camera. The measured heat responses are then analyzed using model-agnostic meta-learning to estimate the coating thickness, which is visualized throughout the inspection surface of the steel structure. Current coating thickness estimation methods rely on point measurement and their inspection area is limited to a single point, whereas the proposed method can inspect a larger area with higher accuracy. In contrast to previous ANN-based methods, which require a large amount of data for training and validation, the proposed method can estimate the coating thickness using only 10- pixel points for each material. In addition, the proposed model has broader applicability than previous methods, allowing it to be applied to various materials after meta-training. The performance of the proposed method was validated using laboratory-scale and field tests with different coating materials; the results demonstrated that the error of the proposed method was less than 5% when estimating coating thicknesses ranging from 40 to 500 ㎛.

• 전자공학회논문지A
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• 제31A권7호
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• pp.110-116
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• 1994

In this paper a Duty Effective Overlap Scanning method (DEOS) for the improvement of driving efficiency of LC displays which have the RMS voltage responding characteristics is proposed and new processing method of data signals for optimum application of this method is also proposed. Proposed method has a few advantages such as the increment of duty ratio the increment of driving power loaded on LC cell and the decrement of RMS voltage error rate caused by signal attenuation on electrodes composing of display when compared with the conventional method which is called as optimum voltage amplitude selection method. And also by adopting new data signal processing method which has 3 kinds of voltage levels additional advantage much improving crosstalk phenomenon which is the most serious problems of simple matrix structured display is obtained. For the characteristic estimation new mathematical representation for new overlap scanning method and data signal processing method are induced and defined. And by the defined formula and simulation the characteristics of the proposed method and the conventional method are compared and analyzed. As a result of estimation this new method being able to optimize the overlap rate of scan signal and using 3 levels of data signals has the characteristic which can improve the driving efficiency of LC displays.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.823-832
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• 2011

본 논문은 orthogonal frequency division multiplexing (OFDM) 통신에서 효율적인 블라인드(blind) 주파수 옵셋 추정 방식을 제안한다. 제안된 방식은 오버샘플링과 OFDM 시스템의 cyclic prefix (CP)를 이용하여 시간차가 있는 2개의 OFDM 신호 블록을 얻고 이를 이용하여 블라인드 주파수 옵셋 추정을 위한 비용함수를 정의한다. 본 논문에서는 제안된 비용함수가 코사인 함수로 근사화 될 수 있음을 보였으며 코사인 함수의 기본적인 특성을 이용하여 주파수 옵셋을 추정할 수 있는 폐쇄형(closed form) 추정 공식을 유도하였다. 이 코사인 함수를 이용하면 전체 주파수 옵셋 범위에 대한 탐색 없이 최저 비용함수 값을 쉽게 계산할 수 있기 때문에 주파수 옵셋 추정이 효율적이다. 제안된 방식은 탐색이 필요 없기 때문에 기존의 블라인드 ML 기법보다 계산량이 약 97% 감소하며 컴퓨터 시뮬레이션 결과 평균제곱오차 (mean square error, MSE) 성능이 기존의 ML 기법이나 MUSIC 방식보다 우수함을 보였다.

• 디지털산업정보학회논문지
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• 제10권4호
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• pp.71-78
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• 디지털산업정보학회논문지
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• 제10권4호
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• pp.63-70
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• ETRI Journal
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• 제30권1호
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• pp.170-172
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• 2008

A substitution box (S-box) plays a central role in cryptographic algorithms. In this paper, an efficient method for designing S-boxes based on chaotic maps is proposed. The proposed method is based on the mixing property of piecewise linear chaotic maps. The S-box so constructed has very low differential and linear approximation probabilities. The proposed S-box is more secure against differential and linear cryptanalysis compared to recently proposed chaotic S-boxes.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2569-2572
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• 2003

In this paper, we Proposed the inverted pendulum control method using single neuron neural network that have weights as PID parameters. The proposed method has three inputs(proportion, integration, differentiation term of the error), and uses weights as P, I, D parameters. In order to verify the effectiveness of the proposed method, we experimented on the rotary inverted pendulum with load effect disturbance. The results showed the effectiveness and robustness of the proposed pendulum controller.