• 한국도로학회논문집
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• 제17권6호
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• pp.11-18
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• 2015

PURPOSES : The purpose of this thesis is to evaluate the effectiveness of an active noise cancellation (ANC) system in reducing the traffic noise level against frequencies from the predictive model developed by previous research. The predictive model is based on ISO 9613-2 standards using the Noble close proximity (NCPX) method and the pass-by method. This means that the use of these standards is a powerful tool for analyzing the traffic noise level because of the strengths of these methods. Traffic noise analysis was performed based on digital signal processing (DSP) for detecting traffic noise with the pass-by method at the test site. METHODS : There are several analysis methods, which are generally divided into three different types, available to evaluate traffic noise predictive models. The first method uses the classification standard of 12 vehicle types. The second method is based on a standard of four vehicle types. The third method is founded on 5 types of vehicles, which are different from the types used by the second method. This means that the second method not only consolidates 12 vehicle types into only four types, but also that the results of the noise analysis of the total traffic volume are reflected in a comparison analysis of the three types of methods. The constant percent bandwidth (CPB) analysis was used to identify the properties of different frequencies in the frequency analysis. A-weighting was applied to the DSP and to the transformation process from analog to digital signal. The root mean squared error (RMSE) was applied to compare and evaluate the predictive model results of the three analysis methods. RESULTS : The result derived from the third method, based on the classification standard of 5 vehicle types, shows the smallest values of RMSE and max and min error. However, it does not have the reduction properties of a predictive model. To evaluate the predictive model of an ANC system, a reduction analysis of the total sound pressure level (TSPL), dB(A), was conducted. As a result, the analysis based on the third method has the smallest value of RMSE and max error. The effect of traffic noise reduction was the greatest value of the types of analysis in this research. CONCLUSIONS : From the results of the error analysis, the application method for categorizing vehicle types related to the 12-vehicle classification based on previous research is appropriate to the ANC system. However, the performance of a predictive model on an ANC system is up to a value of traffic noise reduction. By the same token, the most appropriate method that influences the maximum reduction effect is found in the third method of traffic analysis. This method has a value of traffic noise reduction of 31.28 dB(A). In conclusion, research for detecting the friction noise between a tire and the road surface for the 12 vehicle types needs to be conducted to authentically demonstrate an ANC system in the Republic of Korea.

• Journal of applied mathematics & informatics
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• 제30권1_2호
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• pp.235-244
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• 2012

In this paper, we solve the three-dimensional biharmonic equation with Dirichlet boundary conditions of second kind using the full multigrid (FMG) algorithm. We derive a finite difference approximations for the biharmonic equation on a 18 point compact stencil. The unknown solution and its second derivatives are carried as unknowns at grid points. In the multigrid methods, we use a fourth order interpolation to producing a new intermediate unknown functions values on a finer grid, and the full weighting restriction operators to calculating the residuals at coarse grid points. A set of test problems gives excellent results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.586-591
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• 2002

Recently, the research and discussion to set up the evaluation standard for nor impact noises in multistory residential buildings has been vividly carried out In Korea. Therefore, the correlation between the methods and auditory responses was investigated through this research to investigate the applicability of the L index evaluation method and the reverse A characteristics evaluation method that are listed in JIS A 1419 since Japanese circumstance are similar to Korean after evaluating the duality of Korean multistory residential buildings. As a result, it was found that the correlation between the value resulted from L index evaluation and the value from reverse A characteristics evaluation is high. In addition, it was also revealed that human responses to each Impacter was similar. Consequently, it is considered th:31 the tendency about the two methods would be similar.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
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• pp.70-73
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• 2007

Many methods have been developed to overcome the PAPR(peak-to-average power ratio) problem. Selective mapping(SLM) partial transmit sequence(PTS), subblock phase weighting(SPW) and gradient descent(GD) are used widely to reduce the PAPR. In this paper, we present a effective PAPR reduction method, decrease the calculation through Radix-2 DIF IFFT procedure and GD method. and can transmit selecting data sequence that satisfy threshold value as one part of proposed method, in case satisfy fixed threshold value, or transmit selecting data sequence with the lower papr operating remained part for performance improvement.

• 한국멀티미디어학회논문지
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• 제5권6호
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• pp.609-615
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• 2002

본 논문은 LCD 모니터 상에서 영상 향상을 위한 콘트라스트 제어방식을 제안하였다. 제안한 방식은 입력되는 필드 혹은 프레임 중에서 화소의 최대 값과 최소 값을 판별하고 이를 이용하여 화면의 개선 정도를 결정한다. 필드 또는 프레임의 메모리가 필요하지 않고, 기존의 방식에 비해 하드웨어 구성이 간단하여 실시간 처리를 요하는 분야에 쉽게 적용 가능하다 또한 입력되는 콘트라스 영역의 가중치 값을 변화시킴으로써 콘트라스트 제어가 가능하다 제안한 방법은 콘트라스트 제어 알고리즘과 룩업 테이블을 이용한 영상의 모드에 따라선택적으로 가중치 기울기를 구간별로 달리하여 개선된 영상을 얻는다. 제안한 다계조 콘트라스트 제어 방식을 컴퓨터 시뮬레이션을 통하여 검증하였으며, 시뮬레이션을 통해 영상을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.284-286
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• 2009

In this paper, we consider a cognitive radio system operating as secondary user. It uses an empty channel that is not currently used by primary users having the license to the channel. In the previous works, secondary user looks for an empty channel by choosing any channel in order or randomly and by sensing the channel to distinguish whether primary users are using. But if primary user is fixed type, we will find an empty channel faster than the mentioned channel selecting methods by using a method considering prior information about cases that primary user used the channel, since it is possible to analogize the channel access possibility of primary user according to regular time and position. Therefore, we propose a channel searching method based on the channel list for the purpose of reducing the channel searching time and improving throughput of secondary users. Firstly, we determine a weighting value of each channel based on the history of channel activities of primary users. This value is added to current channel state buffer and we search an empty channel from channel with smallest value to one with the biggest value. Finally, we compare the performances of the proposed method with those of the sequential channel searching and the random channel searching methods in terms of the average channel searching time and the average number of transmissions of secondary user.

• 대한전자공학회논문지SP
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• 제37권4호
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• pp.20-28
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• 2000

오차확산 하프토닝 기법은 연속계조 영상을 이진영상으로 생성시 우수한 재현성을 보인다. 그러나 표시오차의 특성분석에서 경계정보의 재현성이 다소 떨어지는 특성을 보인다. 이러한 경계정보의 재현성 개선하기 위해 전처리 필터를 적용하는 오차확산 기법을 제안한다. 제안한 전처리 필터는 원영상의 수평 및 수직 방향의 미분값, 필터의 가중치 함수로 구성된다. 첫째, 원영상의 수평 및 수직 방향의 미분값은 현재 화소를 중심으로 하여 $3{\times}3$ 인접화소에 Sobel 연산자를 적용시켜 얻는다. 둘째, 필터의 가중치 함수는 미분값의 크기를 포함하는 함수와 미분값의 부호로 구성된다. 제안한 기법을 적용한 하프토닝 영상은 경계가 강조되어 시각적으로 선명한 결과를 보인다. 원영상과 오차확산된 하프토닝 영상과의 차이(표시오차)를 환상 평균 전력 스펙트럼 밀도를 이용하여 기존의 경계강조 오차확산 알고리즘과 비교한다.

• 한국통신학회논문지
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• 제14권5호
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• pp.549-560
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• 1989

본 논문은 광대역 신호처리 DCMP 알고리즘에서 필터로서 동작하는 초기가중치의 설정 방법을 제안하였고 컴퓨터 시뮬레이션을 통해 최적의 Tap 수를 결정하는 방법을 기술하였다. 광대역 비임 형성기를 FiR 필터 개념으로 분석하여 원하는 신호의 입사 방향에 대한 제한 조건을 얻었고 이 제한 조건으로 부터 적응 속도가 빠른 초기 가중치를 설정하였다. 본 논문에서 제안된 초기 가중치를 기존의 DCMP프로세서나 공간 영역 평균법을 수행하는 프로세서에 적용할 때 원하는 신호의 입사 방향과 일치하는 잡음 그리고 Cohenrent Noise를 반복 적용하는 과정에서 동시에 제거할 수 있음을 컴퓨터 시뮬레이션으로 확인 하였다.

• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.535-543
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• 2001

This paper presents the ride comfort analysis of a vehicle based on wavelet transform. Traditionally, the objective evaluation of impact harshness is based on the vibration dose value (VDV) and frequency weighting method. These methods do not consider the damping effect of the suspension system of a vehicle. In this paper, the damping is estimated using wavelet transform based on Morlet mother wavelet and its effect is considered for the subjective evaluation of impact harshness of a car.

• 대기
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• 제26권4호
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• pp.697-709
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• 2016

This study estimates and evaluates the extreme value of 30 m-resolution daily maximum and minimum temperatures over South Korea, using inverse distance weighting (IDW), parameter-elevation regression on independent slopes model (PRISM) and generalized extreme value (GEV) method. The three experiments are designed and performed to find the optimal estimation strategy to obtain extreme value. First experiment (EXP1) applies GEV firstly to automated surface observing system (ASOS) to estimate extreme value and then applies IDW to produce high-resolution extreme values. Second experiment (EXP2) is same as EXP1, but using PRISM to make the high-resolution extreme value instead of IDW. Third experiment (EXP3) firstly applies PRISM to ASOS to produce the high-resolution temperature field, and then applies GEV method to make high resolution extreme value data. By comparing these 3 experiments with extreme values obtained from observation data, we find that EXP3 shows the best performance to estimate extreme values of maximum and minimum temperatures, followed by EXP1 and EXP2. It is revealed that EXP1 and EXP2 have a limitation to estimate the extreme value at each grid point correctly because the extreme values of these experiments with 30 m-resolution are calculated from only 60 extreme values obtained from ASOS. On the other hand, the extreme value of EXP3 is similar to observation compared to others, since EXP3 produces 30m-resolution daily temperature through PRISM, and then applies GEV to that result at each grid point. This result indicates that the quality of statistically produced high-resolution extreme values which are estimated from observation data is different depending on the combination and procedure order of statistical methods.