• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.895-896
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• 2008

We propose a adaptive combination of affine projection algorithm (APA) filters with different update interval. Two APA filters with different update interval are adapted independently in order to keep the advantages of both component filters. This novel scheme provides improvement of performance in term of the convergence rate and the steady-state error. Experimental results show good properties of the proposed algorithm.

• The Journal of the Acoustical Society of Korea
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• 제17권2E호
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• pp.3-9
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• 1998

Since the introduction of hands-free phone set and teleconferencing system, acoustic echo cancellation has been a challenge for engineers. Recently many researches have shown that the best solution for the acoustic echo compensation problem is represented by an adaptive filter which iteratively tries to identify the unknown impulse response of the system from loudspeaker to microphone. In this paper, we apply the delayless subband adaptive filters and fast affine projection algorithm for the identification of room impulse response. Simulation results show 3∼8 dB more enhanced performance than conventional fullband adaptive filters or subband adaptive filters. In addition, fast affine projection algorithm shows better convergence speed at the expense of the low computational complexity than conventional LMS algorithm.

• 한국통신학회논문지
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• 제15권9호
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• pp.764-774
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• 1990

알고리즘 구조가 간단하고 실제적 응용이 쉬운 LMS 알고리즘을 이용한 적응 필터 설계에서 횡단필터, 격자필터 및 결합처리 격자필터의 예측기 특성을 비교 연구하였다. 실제적 설계를 위해 각 필터의 LMS 알고리즘의 이론적 배경과 구성을 보였고 최적 가중치 벡터와 반사계수의 적응 수렵조건을 명시하였으며 이를 컴퓨터 시뮬레이션을 통하여 나타내었다. 또한 정지및 비정지 입력 신호에 대한 이들 필터의 오차신호 특성과 잡음특성을 비교하였고 결합처리 격자필터가 이들 LMS 알고리즘을 이용한 적응 필터에서 가장 우수한 특성을 갖고 있음을 보였다.

• Kyungpook Mathematical Journal
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• 제15권2호
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• pp.183-189
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• 1975

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제13권1호
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• pp.47-69
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• 2006

In this paper, an idea of graded fuzzy net is introduced; its convergence is studied; Relations between g-net and g-filter are established in L-fuzzy setting.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.247-250
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• 2003

디지털 2차 적응 IIR 대역 통과 필터의 진폭 특성을 해석, 적응 계수와 입력 신호의 중심 주파수 그리고 극의 각과의 관계를 해석하고, 적응 계수의 경계를, 기존에 발표된 세 알고리즘을 예로 들어, 평가하였다.

• 한국세라믹학회지
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• 제56권1호
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• pp.98-103
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• 2019

Optical filters to control light wavelength of displays or cameras are fabricated by multi-layer stacking process of low and high index thin films. The process of multi-layer stacking of thin films has received much attention as an optimal process for effective manufacturing in the optical filter industry. However, multi-layer processing has disadvantages of complicated thin film process, and difficulty of precise control of film morphology and material selection, all of which are critical for transmittance and coloring effect on filters. In this study, the composite $TiO_2$, which can be used to control of UV absorption, coated on nano hollow silica sol, was synthesized as a coating material for optical filters. Furthermore, systematic analysis of the process parameters during the chemical reaction, and of the structural properties of the coating solutions was performed using SEM, TEM, XRD and photo spectrometry. From the structural analysis, we found that the 85 nm nano hollow silica with 2.5 nm $TiO_2$ shell formation was successfully synthesized at proper pH control and titanium butoxide content. Photo luminescence characteristics, excited by UV irradiation, show that stable absorption of 350 nm-light, correlated with a 3.54 eV band gap, existed for the $TiO_2$ shell-nano hollow silica reacted with 8.8 mole titanium butoxide solution. Transmittance observed on substrate of the $TiO_2$ shell-nano hollow silica showed effective absorption of 200-300 nm UV light without deterioration of visible light transparency.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제26권4호
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• pp.255-265
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• 2019

In this paper, we define the notion of (L, ∗, ⊙)-quasiuniform convergence spaces on ecl-premonoid. From (L, ∗, ⊙)-quasiuniform structures, we can obtain various (L, ∗, ⊙)-quasiuniform convergence structures and give their examples.

• 융합신호처리학회논문지
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• 제24권1호
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• pp.1-14
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• 2023

Underwater images carry information that is useful in the fields of aquaculture, underwater military security, navigation, transportation, and so on. In this research, we transmitted an underwater image through various underwater mediums in the presence of underwater turbulence and beam attenuation effects using a high-speed visible optical carrier signal. The optical beam undergoes scintillation because of the turbulence and attenuation effects; therefore, distorted images were observed at the receiver end. To understand the behavior of the communication media, we obtained the bit error rate (BER) performance of the system with respect to the average signal-to-noise ratio (SNR). Also, the structural similarity index (SSI) and peak SNR (PSNR) metrics of the received image were evaluated. Based on the received images, we employed suitable nonlinear filters to recover the distorted images and enhance them further. The BER, SSI, and PSNR metrics of the specific nonlinear filters were also evaluated and compared with the unfiltered metrics. These metrics were evaluated using the on-off keying and binary phase-shift keying modulation techniques for the 50-m and 100-m links for beam attenuation resulting from pure seawater, clear ocean water, and coastal ocean water mediums.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.583-591
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• 2020

Environmental problems have showen over the past decades due to the rapid development of the world economy and the continued growth of the population. Ocher has been widely used for water treatment research, but few studies have been conducted on adsorption of air pollutants using ocher and porous diatomite earth for indoor air purification. In this study, ocher and diatomite earth were sintered with filters to remove indoor air pollutants. The four types of TMA, H₂S, NH₃ and CH₃COOH were used to study the adsorption efficiency of ocher and porous diatomite filters. With the proper use of ocher, diatomite and copper catalysts, indoor air pollutants could be adsorbed. Alkaline substances (TMA and NH₃) and acidic substances (H₂S and CH₃COOH) were able to adsorb at 120 and 90 minutes, respectively.