• 대한원격탐사학회지
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• 제19권5호
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• pp.403-409
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• 2003

Since SPOT4 satellite contained VEGETATION 1 sensor launched, the noise in VEGETATION data was occasionally arisen a difficulty for the data traitement. Blind line noise types were studied in VEGETATION-l short wave infrared channel(SWIR). In order to provide a precis product, the procedure for removing this noise is strongly recommended. In the case that the blind values are clearly distinguished from contamination-free values a simple threshold method was applied, while a changeable threshold method was used for the blind value mixed with contamination-free values. New algorithm presented in this study is consists of two method for each type of SWIR blind. After removing blind line, there were again some residual pixels of blind, because the threshold is not determinated sufficiently low. Lower threshold could remove the blind line as well as the contamination-free pixels. Nevertheless, the results showed a good qualitative improvement as compared with other algorithm.

• Environmental Analysis Health and Toxicology
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• 제14권4호
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• pp.165-174
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• 1999

This study was conducted to analyze the priority of environmental problems in Korea by investigating the environmental professionals' perception. The delphi technique was applied to identify their risk perception towards some specific items related with pollution. A standardized questionnaire on environmental problems and their priorities was used to 74 subjects. In the questionnaire, the environmental problems were divided into the general ones,9 items, and the specific ones,30 items. Also, the perception was associated with two points of view which were the risk on general human health or ecosystem, and on the present situation in Korea. The priority of risk from general environmental problems on human health or ecosystem was analyzed in the order of 'water pollution', 'air pollution', 'soil contamination', 'waste', 'toxic chemical pollutants', 'food contamination', 'ocean contamination', 'odor pollution', and 'noise pollution'. The priority of risk on the present situation in Korea was analyzed in the order of 'water pollution','air pollution','waste','toxic chemical pollutants','food contamination','soil contamination','ocean contamination','odor pollution', and 'noise pollution'. And these priorities were significantly related with the characteristics of respondents such as sex, age, and major concerned area. However, for the first five priorities of risk from the specific environmental problems on human health or ecosystem, the environmental professionals agreed with 'automotive vehicle exhaust', 'domestic and industrial source pollutants to surface water', '$CO_2$nd g1oba1 warming effect','toxic air pollutant' and 'industrial source air pollution'. The priorities of risk on the present situation in Korea were similar to these results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4390-4407
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• 2019

The paucity of pilot signals in Massive MIMO system is a vital issue. To accommodate substantial number of users, pilot signals are reused. This leads to interference, resulting in pilot contamination and degrades channel estimation at the Base Station (BS). Hence, mitigation of pilot contamination is exigency in Massive MIMO system. The proposed Time Shifted Pilot Signal Transmission with Pilot signal Hopping (TSPTPH), addresses the pilot contamination issue by transmitting pilot signals in non-overlapping time interval with hopping of pilot signals in each transmission slot. Hopping is carried by switching user to new a pilot signal in each transmission slot, resulting in random change of interfering users. This contributes to the change in channel coefficient, which leads to improved channel estimation at the BS and therefore enhances the efficiency of Massive MIMO system. In this system, Uplink Signal Power to Interference plus Noise Power Ratio (SINR) and data-rate are calculated for pilot signal reuse factor 1 and 3, by estimating the channel with Least Square estimation. The proposed system also reduces the uplink Signal power for data transmission of each User Equipment for normalized spectral efficiency with rising number of antennas at the BS and thus improves battery life.

• 응용통계연구
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• 제24권5호
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• pp.905-914
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• 2011

영상처리 분야에서 원래의 순수 이미지를 오염시키는 잡음을 제거하는 것은 매우 중요한 문제이다. 그러나 여러 가지 원인으로 인하여 발생하는 잡음의 발생을 완벽하게 막는 것은 현실적으로 불가능하다. 따라서 영상에 포함되어 있는 잡음을 제거하거나 최대한 줄이는 것이 매우 중요한 과제이다. 본 연구에서는 이미지를 오염시키고 있는 잡음의 상대적인 크기를 측정하여 잡음의 분산의 수준을 추정하고, 이를 영상처리 분야에서 자주 사용되는 잡음제거 기법인 시그마 필터에 응용하여 잡음을 효과적으로 제거하는 통계적 알고리즘을 제시하였다. 결론적으로, 잡음의 분산의 수준에 관계없이 본 연구에서 제안한 통계적 잡음제거 방법론을 통해 기존의 시그마 필터보다 현저하게 개선된 결과를 얻을 수 있었다.

• Earthquakes and Structures
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• 제15권3호
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• pp.263-273
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• 2018

Operational modal analysis is being widely used in aerospace, mechanical and civil engineering. Common research fields include optimal design and rehabilitation under dynamic loads, structural health monitoring, modification and control of dynamic response and analytical model updating. In many practical cases, influence of noise contamination in the recorded data makes it difficult to identify the modal parameters accurately. In this paper, an improved frequency domain method called Enhanced Least Square Complex Frequency (eLSCF) is developed to extract modal parameters from noisy recorded data. The proposed method makes the use of pre-defined approximate mode shape vectors to refine the cross-power spectral density matrix and extract fundamental frequency for the mode of interest. The efficiency of the proposed method is illustrated using an example five story shear frame loaded by random excitation and different noise signals.

• 한국광학회지
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• 제25권3호
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• pp.142-145
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• 2014

본 논문에서는 광 스캐닝 홀로그래피 기술을 이용하여 실제 물체의 복소 홀로그램 정보를 스펙클 잡음 없이 촬영하였다. 촬영된 복소 홀로그램 정보를 수치적인 방법으로 복원한 뒤 결맞음 광원과 CCD 카메라를 이용하여 촬영한 실제 물체의 영상과 비교하여 스펙클 잡음에 의한 오염도를 평가하였다. 스펙클 잡음에 의한 오염도를 정량적으로 평가하기 위하여 두 영상의 스펙클 패턴의 대비 수치를 이용하였다.

• Multiscale and Multiphysics Mechanics
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• 제1권3호
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• pp.261-270
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• 2016

The longitudinal velocity (forward speed) having significant importance in proper running of railway wheelset on track, depends greatly upon the adhesion ratio and creep analysis by implementation of suitable dynamic system on contamination. The wet track condition causes slip and slide of vehicle on railway tracking, whereas high speed may also increase slip and skidding to severe wear and deterioration of mechanical parts. The basic aim of this research is to design appropriate model aimed estimator that can be used to control railway vehicle forward velocity to avoid slip. For the filtration of disturbance procured during running of vehicle, the kalman filter is applied to estimate the actual signal on preferered samples of creep co-efficient for observing the applied attitude of noise. Thus error level is detected on higher and lower co-efficient of creep to analyze adhesion to avoid slip and sliding. The skidding is usually occurred due to higher forward speed owing to procured disturbance. This paper guides to minimize the noise and error based upon creep coefficient.

• 한국음향학회지
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• 제15권4호
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• pp.83-92
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• 1996

본 연구에서는 음성인식기의 성능이 잡음환경하에서 급격히 저하되는 것을 완화하기 위해, 성능저하의 원인인 롬바드효과의 보정과 잡음의 제거방법을 제안하였다. 롬바드 효과는 조용한 환경에서 발성된 음성에 비해, 스펙트럼 포락과 발성음의 세기를 변이 시키는 것으로 모델링하였고, 변이의 제거를 위해 스펙트럼 크기의 정규화와 켑스트럼 변환을 사용하였다. 주변 잡음의 첨가에 의한 음성신호의 왜곡은 스펙트럼 차감법을 사용하여 완화하였고, 음성의 동적인 특성을 강조하기 위해 대역통과 필터링을 하였다. 잡음환경에서 발성된 롬바드 음성의 분석 및 잡음처리 기술의 개발과 평가를 위해, 음성인식 기술의 적용이 예상되는 자동차, 전시장, 시내 공중전화 부스, 거리, 전산실 잡음을 이용하여 롬바드 음성을 수집하여 실험하였다. 제안한 방법을 여러 가지 잡음환경하에서 음성인식에 적용한 결과, 효과적인 잡음처리 방법임을 확인할 수 있었다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.3106-3106
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• 2001

Imaging spectrometry or hyperspectral imaging is a recent development that makes possible quantitative and qualitative measurement for food quality and safety. This paper presents the research results that a hyperspectral imaging system can be used effectively for detecting fecal (from duodenum, cecum, and colon) and ingesta contamination on poultry carcasses from the different feed meals (wheat, mile, and corn with soybean) for poultry safety inspection. A hyperspectral imaging system has been developed and tested for the identification of fecal and ingesta surface contamination on poultry carcasses. Hypercube image data including both spectral and spatial domains between 430 and 900 nm were acquired from poultry carcasses with fecal and ingesta contamination. A transportable hyperspectral imaging system including fiber optically fabricated line lights, motorized lens control for line scans, and hypercube image data from contaminated carcasses with different feeds are presented. Calibration method of a hyperspectral imaging system is demonstrated using different lighting sources and reflectance panels. Principal Component and Minimum Noise Fraction transformations will be discussed to characterize hyperspectral images and further image processing algorithms such as image band ratio of dual-wavelength images and its histogram stretching with thresholding process will be demonstrated to identify fecal and ingesta materials on poultry carcasses. This algorithm could be further applied for real-time classification of fecal and ingesta contamination on poultry carcasses in the poultry processing line.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.465-465
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• 2009

Wind power is one of the most reliable renewable energy sources and the installed wind turbine capacities are increasing radically every year. Although wind power has been favored by the public in general, the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased. Low noise wind turbine design is becoming more important as noise is spreading more adverse effect of wind turbine to public. This paper demonstrates the design of 10 kW class wind turbines, each of three blades, a rotor diameter 6.4m, a rated rotating speed 200 rpm and a rated wind speed 10 m/s. The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade has been known as trailing edge noise from the outer 25% of the blade. Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at $1.02{\times}10^6$ with a lift performance, which is resistant to surface contamination and turbulence intensity. The objective in the low design process is to reduce noise emission, while sustaining high aerodynamic efficiency. Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al. and Lowson associated with typical wind turbine operation conditions. During the airfoil redesign process, the aerodynamic performance is analyzed to minimize the wind turbine power loss. The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis. The new optimized airfoil clearly indicates reduction of total SPL about 3 dB and higher aerodynamic performance.