• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2019년도 춘계학술대회
• /
• pp.429-431
• /
• 2019

이미지 프로세싱에서 잡음은 영상의 품질에 직접적인 영향을 미치는 요소이며, 특히 영상 분할, 에지 검출, 영상 인식과 같은 알고리즘을 포함하는 시스템의 처리과정에 악영향을 미친다. 따라서 전처리 과정으로 잡음 제거가 중요한 역할을 하고 있으며, 이를 위해 다양한 기법들이 제시되었다. 본 논문에서는 Salt and Pepper 잡음의 밀도가 높은 환경에서 효율적으로 잡음을 제거하기 위한 알고리즘을 제안하였다. 제안한 알고리즘은 잡음의 밀도에 따라 필터링 마스크를 단계적인 확장하여 잡음을 제거하였으며, 밀도가 높은 영역에서도 우수한 잡음 제거 성능을 보였다. 제안한 알고리즘의 성능 평가를 위해 시뮬레이션을 통해 기존 방법과 제안한 알고리즘을 비교 분석하였다.

• 한국소음진동공학회논문집
• /
• 제17권3호
• /
• pp.264-273
• /
• 2007

A smart panel with structural sensors and actuators for minimizing noise radiation or transmission is described in the paper with the concept of active structural acoustical control. The sensors and actuators are both quadratically shaped piezoelectric polyvinylidene fluoride(PVDF) Polymer films to implement a volume velocity sensor and uniform force actuator respectively. They are collocated on either side of the panel to take advantage of direct velocity feedback(DVFB) strategy, which can guarantee a robust stability and high performance as long as the sensor-actuator response is strictly positive real(SPR). However, the measured sensor-actuator response of the panel showed unexpected result with non-SPR property. In the paper, the reason of the non-SPR property is investigated by theoretical analysis, computer simulation and experimental verification. The investigation reveals that the arrangement of collocated piezoelectric PVDF sensor and actuator pair on a panel is not relevant to get a high feedback gain and good performance with DVFB strategy.

• Journal of Biosystems Engineering
• /
• 제31권4호
• /
• pp.315-322
• /
• 2006

A torsional damper comprised of two stage pre-dampers was used to reduce the rattle noise generated in the PTO gear box of a direct engine-PTO driveline of agricultural tractors. It was designed and mounted to the engine flywheel to reduce the torque fluctuation-induced speed variations at the driving gears in the PTO gearbox, which were found to be main cause of the rattle noise. The effects of a hysteresis torque and a torsional stiffness of the damper on the speed variation were analyzed using an 11 degree of freedom non-linear model of the damped PTO driveline. The torsional damper was represented by a single degree of freedom model with 7 parameters. Under a constant hysteresis torque, velocity variation was reduced with decrease in the torsional stiffness of the damper. The velocity variation was also decreased with decrease in the hysteresis torque under a constant torsional stiffness. Optimum values of the torsional stiffness and hysteresis torque were obtained by the model simulation for the PTO driveline under the study. When the optimum values of the damper were used, the sound pressure level of the rattle noise was reduced by 81%, resulting in a reduction of 15dB(A). The optimum damper also reduced the engine speed variation, resulting in a reduction of 80% at the driving gears in the PTO gearbox. The torsional damper showed a good performance in reducing the rattle noise caused by the speed variation in the direct engine-PTO driveline.

• 한국소음진동공학회논문집
• /
• 제11권4호
• /
• pp.5-12
• /
• 2001

This paper presents the simulation methodology of the interior noise of vehicle using the frequency response function based hybrid modeling of the system which consists of multi-subsystem models obtained by the test or analysis. The complex systems such as a trimmed body of high modal density and a powertrain were modeled by using experimental data, and a sub-frame of a vehicle of low modal density was modeled by finite element data. Modeling of the whole system was executed and validated in the two stages. The first stave is combining the trimmed body and the sub-frame, and the second stage is attaching the powertrain, which is a exciting source, to the combined model of the first stage. The input force to the system was modeled as an equivalent force in the virtual space, which was obtained from impedance method using the FRFs of the powertrain and the responses. The interior noise predicted by the proposed method was very close to the direct measurement, which showed feasibility of the proposed modeling procedure. Since the methodology is easily applied to both the transfer path analysis of structure-borne noise and the analysis of noise contribution of a sub-system, it is expected to be a strong tool for design change of a vehicle in the earlier stare.

• ETRI Journal
• /
• 제34권2호
• /
• pp.190-198
• /
• 2012

An adaptive correlation noise model (CNM) construction algorithm is proposed in this paper to increase the efficiency of parity bits for correcting errors of the side information in transform domain Wyner-Ziv (WZ) video coding. The proposed algorithm introduces two techniques to improve the accuracy of the CNM. First, it calculates the mean of direct current (DC) coefficients of the original WZ frame at the encoder and uses it to assist the decoder to calculate the CNM parameters. Second, by considering the statistical property of the transform domain correlation noise and the motion characteristic of the frame, the algorithm adaptively models the DC coefficients of the correlation noise with the Gaussian distribution for the low motion frames and the Laplacian distribution for the high motion frames, respectively. With these techniques, the proposed algorithm is able to make a more accurate approximation to the real distribution of the correlation noise at the expense of a very slight increment to the coding complexity. The simulation results show that the proposed algorithm can improve the average peak signal-to-noise ratio of the decoded WZ frames by 0.5 dB to 1.5 dB.

• 대한전자공학회논문지TC
• /
• 제49권5호
• /
• pp.72-76
• /
• 2012

이동성이 있는 센서 노드로 구성 된 센서 네트워크를 효율적으로 사용하기 위하여 고려해야 할 사항 중 중요한 것이 자원의 효율적인 사용과 신호를 빠르고 정확하게 보내는 것이다. 본 논문에서는 무선 센서 네트워크 내에서 SNR(Signal to Noise Ratio)과 릴레이 노드의 신호 증폭률 그리고 노드와 노드 간 직접적으로 통신하는 경우 경로의 이득의 변화에 따른 무선 센서 네트워크의 특성에 대하여 분석하고 다수의 협동 릴레이 노드가 존재할 때 선택기준을 제시하고 이에 따른 영향을 정량적으로 평가하였다.

• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.994-1003
• /
• 2016

Two major obstacles in the utilization of electrical vehicles are their price and range. The collaboration of direct torque control (DTC) with induction motor (IM) is preferred for its low cost, easy implementation, and parameter independency. However, in terms of edges, the method has drawbacks, such as variable switching frequency and undesired current harmonic distortion. These drawbacks result in acoustic noise, reduced efficiency, and electromagnetic interference. A feed-forward approach for stator-flux-oriented DTC with space vector pulse-width modulation is presented in in this paper. The outcome of the proposed method is low current harmonic distortion with fixed switching frequency while preserving the torque performance and simple application feature of basic DTC. The method is applicable to existing and forthcoming IM drive systems via software adaptation. The validity of the proposed method is confirmed by simulation and experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.2034-2036
• /
• 2004

In this paper, a low noise amplifier (LNA) in receiver of Low Noise Block Down Converter (LNB) for direct broadcasting service (DBS) is implemented by using GaAs HEMT. The LNA is designed for operation between 10.7GHz-12.7GHz. The LNA consists of input, output matching circuits, DC-blocks and RF-chokes. Simulation result of the LNA shows that a noise figure is less than 1.4dB and a gain is greater than 9.2dB in the bandwidth of 10.7 to 12.7GHz with good flatness of 0.1dB.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2004년도 하계학술대회
• /
• pp.369-372
• /
• 2004

In this paper, a low noise amplifier (LNA) in receiver of Low Noise Block Down Converter (LNB) for direct broadcasting service (DBS) is implemented by using GaAs HEMT The LNA is designed for operation between 10.7GHz-12.7GHz. The LNA consists of input, output matching circuits, DC-blocks and RF-chokes. The result of simulation of the LNA shows that a noise figure is less than 1.4dB and a gain is gloater than 9.2dB in the bandwidth of 10.7 to 12.7GHz with good flatness of 0. ldB

• Journal of information and communication convergence engineering
• /
• 제7권3호
• /
• pp.383-391
• /
• 2009

In this paper, blind equalization using a modified Fuzzy C-Means algorithm with Gaussian Weights (MFCM_GW) is attempted to the heavy noise-corrupted channels. The proposed algorithm can deal with both of linear and nonlinear channels, because it searches for the optimal channel output states of a channel instead of estimating the channel parameters in a direct manner. In contrast to the common Euclidean distance in Fuzzy C-Means (FCM), the use of the Bayesian likelihood fitness function and the Gaussian weighted partition matrix is exploited in its search procedure. The selected channel states by MFCM_GW are always close to the optimal set of a channel even the additive white Gaussian noise (AWGN) is heavily corrupted in it. Simulation studies demonstrate that the performance of the proposed method is relatively superior to existing genetic algorithm (GA) and conventional FCM based methods in terms of accuracy and speed.