• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.227-229
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• 2021

현대 사회는 아날로그 시대를 지나 디지털 영상시대로 나아가고 있으며, 이러한 시대의 흐름에 발맞춰 탐사로봇, 의료장비, CCTV 등 다양한 영상 기기들이 우리의 일상생활에 많은 도움을 주고 있다. 하지만 디지털 영상에서 다양한 원인으로 인해 발생하는 잡음들은 영상의 열화 현상을 일으킬 뿐 아니라, 화질을 훼손시키고 악화시킨다. 대표적인 잡음으로 AWGN이 있으며 이를 제거하기 위한 필터의 종류로 평균필터, 메디안필터, 알파 트림드 평균필터 등이 있지만, 이러한 필터들은 고주파 영역에서는 다소 미흡한 잡음 제거 성능을 보인다는 단점이 있다. 따라서 본 논문에서는 영상의 고주파 영역에 존재하는 AWGN을 효과적으로 제거하기 위해 표준편차를 기반한 변형된 공간분할 평균필터를 제안한다.

• 대한방사선기술학회지:방사선기술과학
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• 제24권1호
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• pp.5-9
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• 2001

Over-density of pancreatic duct tail part on the endoscopic retrograde pancreatogram results from patient's position and inserted air during the study. The aim of this paper is to decide the filter angle to obtain an uniform density. Endoscopic retrograde pancreatography was performed to 234 patients, and angled wedge filter was used differently. They are $10^{\circ}$ (47), $20^{\circ}$ (45), $30^{\circ}$ (50), and $40^{\circ}$ (50). We also did not use wedge filter to 42 patients. We decided reliance degree in 95%. The statistical difference was p<0.05. The patients' sex rate was 1.8 : 1 between 18 and 87 years old(average age 58 years). Their body girth was 18.71 cm on the average. Of total 234 patients, difference of right and left average density was 0.01 by $30^{\circ}$ wedge filter, -0.08 $40^{\circ}$ wedge filter and 0.27 non-wedge filter. These average values of difference density were very significant statistically, and standard deviation also was close to regular distribution. In conclusion, there is a usefulness of angled wedge filter for increasing diagnostic value of pancreatic duct tall part on the endoscopic retrograde pancreatogram.

• 한국수산과학회지
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• 제31권6호
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• pp.914-919
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• 1998

육상 수조식 양식장의 유입수에 망목 60$\mu$m 스크린필터 및 조사량 0.5 mWS/$cm^2$ 자외선등, 배출수에 망목 90 $\mu$m 드럼필터를 설치$\cdot$운행하여 어류사육수조의 유입수와 배출수의 정화효과를 검토하였다. 유입 수에 60$\mu$m 스크린필터와 조사량 0.5 mWS/$cm^2$의 UV, 배출수에 90 $\mu$m 드럼필터의 설치$\cdot$운행에 따른 수온, 염분, $NO_3-N,\;NO_2-N,\;NH_4-N,\;PO_4-P$, DO 및 COD에 대한 정화효과는 인정되지 않았다. 그러나, 유입수에 60$\mu$m스크린필터의 설치$\cdot$운행에 의한 부유물질과 탁도는 각각 $48.7\~65.6\%$ (평균, $52.8\%$), $33.3\~42.5\%$ (평균, $35.9\%$)가 제거되었고, 조사량 0.5 mWS/$cm^2$의 UV의 설치$\cdot$운행에 따른 세균 및 비브리오 균수는 각각 $16.7\~20.2\%$ (평균, $19.2\%$), $20.0\~21.9\%$ (평균, $20.9\%$)가 살균되었다. 또한, 배출수에 90 $\mu$m 드럼필터의 설치에 따라 부유물질은 $42.7\~52.6\%$ (평균 $46.9\%$), 탁도는 $27.7\~29.9\%$ (평균 $28.3\%$)의 제거효율을 나타내었다.

• 대한전자공학회논문지TC
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• 제43권10호
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• pp.60-68
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• 2006

OFDM(Orthogonal Frequency Division Multiplexing)은 주파수 선택적 페이딩 환경에서 구현상의 복잡도가 크지 않으면서 우수한 성능을 나타내는 특성을 가지고 있으며 광대역 무선통신 시스템에서 널리 사용되고 있다. OFDM 시스템의 수신기에서 하는 가장 중요한 일 중 하나는 프리앰블의 검출이다. 이 논문에서는 확장된 차동 검출 방식과 유사한 형태를 가지는 이동평균필터를 사용하는 차동 검출 방식을 제안하며 이동평균필터의 크기를 결정하여 다양한 환경에서 최적의 성능을 얻는 방법을 제안한다. 수식에서 최적의 이동평균필터의 크기는 딜레이 스프레드가 커짐에 따라 그리고 신호대잡음비가 커짐에 따라 감소함을 보인다.

• 한국수산과학회지
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• 제36권2호
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• pp.163-169
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• 2003

The floating bead filter was tested for treatment of aquacultural water in a pilot-scale recirculating aquaculture system. Performance of floating bead filter on the removal of total suspended solids (TSS) and the treatment of nitrogen sourer such as total ammonia nitrogen (TAN), nitrite nitrogen and nitrate nitrogen were evaluated. The system was stocked with Nile tilapia at an initial rearing densities of $5\%\;and\;7\%$ over 30 days. The average TSS removal rates were $43.0\;g/m^2{\cdot}day\;and\;39.5\;g/m^2{\cdot}day$ for rearing density of $5\%\;and\;7\%$, respectively. As rearing density increased from $5\%\;to\;7\%$. the TAN removal efficiency decreased from $22.0\%\;to\;17.7\%$. At the rearing densities of $5\%\;and\;7\%$, the average TAN removal rates and removal efficiencies were $38.8\;g/m^2{\cdot}day,\;15.6\%\;and\;37.8\;g/m^2{\cdot}day.\;17.7\%,$ respectively. The average TAN removal rate was $37.8-38.8\;g/m^3{\cdot}day.$ The oxygen consumption by floating bead filter was higher than theoretical oxygen consumption rate by nitrification.

• 한국세라믹학회지
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• 제32권9호
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• pp.989-994
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• 1995

Rigid porous carbon fiber composites with the uniform pore size distribution were prepared by vacuum forming from water slurries containing carbonized PAN fibers, a phenolic resin and ceramic binders. The composites were designed to use for highly efficient carbon fiber filters for particulate filtration and gas adsorption. As the as-received carbon fibers of 1mm in length were milled to an approximate average length of 300${\mu}{\textrm}{m}$, modulus of rupture (MOR) of the composite filter was increased from 1MPa to the value larger than 5 MPa. Modulus of rupture (MOR) for the composite filter fabricated using the milled carbon fiber was increased from 5 MPa to 10 MPa as the carbonization temperature of the PAN fiber was raised from 90$0^{\circ}C$ to 140$0^{\circ}C$. The air permeability and an average pore size of the composite filter were increased from 40 to 270cc/min.$\textrm{cm}^2$ and from 35 to 80${\mu}{\textrm}{m}$, respectively, as the apparent porosity increased from 80 to 95%. It was shown that the MOR of the carbon fiber composite filter was dependent primarily on the average length of carbon fiber, carbonization temperature and the type of bonding materials.

• 말소리와 음성과학
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• 제2권4호
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• pp.145-151
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• 2010

In this paper, a robust feature compensation method is proposed for improving the performance of speech recognition. The proposed method is incorporated into the auto-regressive moving average (ARMA) based feature compensation. We employ variable weights for the ARMA filter according to the degree of speech activity, and pass the normalized cepstral sequence through the weighted ARMA filter. Additionally when normalizing the cepstral sequences in training, the cepstral means and variances are estimated from total training utterances. Experimental results show the proposed method significantly improves the speech recognition performance in the noisy and reverberant environments.

• International Journal of Aeronautical and Space Sciences
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• 제3권1호
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• pp.86-94
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• 2002

The initial alignment of inertial platform for navigation system was considered. An adaptive filtering technique is developed for the system with unknown and varying sway disturbance. It is assumed that the random sway motion is the second order ARMA(Auto Regressive Moving Average) model and performed parameter identification for unknown parameters. Designed adaptive filter contain both a Kalman filter and a self-tuning filter. This filtering system can automatically adapt to varying environmental conditions. To verify the robustness of the filtering system, the computer simulation was performed with unknown and varying sway disturbance.

• 전기학회논문지P
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• 제66권4호
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• pp.200-205
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• 2017

In this paper, we propose a technique to determine the normal and arc of an alternating current using a mixed filter composed of an average filter and a band-pass filter and a frequency analysis. The proposed method uses the moving average filter of the FIR filter structure for noise removal and the band-pass filter of the IIR filter structure for detecting only specific frequency components after normalizing the measured current signal based on the maximum value. After performing Fast Fourier Transform (FFT) using the band-pass filtered signal, the total energy is calculated using the magnitude component of the frequency, and the arc is detected using the magnitude of the calculated energy. In order to show the validity of the proposed method, we experimented with various data and found that arc and steady state can be easily discriminated by calculating spectral energy. Therefore, it is considered that the proposed method can be applied to arc diagnosis of low voltage electric wire.

• 대한전자공학회논문지
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• 제21권1호
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• pp.32-37
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• 1984

본 논문에서는 저역 통과 특성을 나타내는 것으로 알려져 있는 이동 평균 여파기의 마이크로프로세서 구성에 대한 실제적이고 간단한 기법을 연구한 것이다. 설계의 편의를 위하여 이동 평균 여파기에 대한 차단 주파수의 근사식과 필터링 알고리즘도 제시하였다. 상용 마이크로프로세서 Z-80을 사용한 실험 시스템의 몇 가지 실험결과를 제시했다. 고주파 잡음이 효과적으로 제거된 것이 확인되었으며 차단 주설수의 근사식의 결과는 실측결과와 거의 일치됨이 확인되었다.