• 대한원격탐사학회지
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• 제26권5호
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• pp.489-495
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• 2010

초분광 영상은 넓은 범위의 파장 영역의 유용한 정보를 많은 수의 밴드를 통해 취득한다. 하지만, 인접 밴드 간의 상관관계, 계산량, 노이즈로 인해 전처리없이 활용할 경우 부정확한 결과를 도출한다. 따라서 영상에서 노이즈 밴드 추출하여 제거하는 작업이 반드시 필요하다. 기존의 연구들은 영상 전체에 대한 특성치 만을 이용하였기 때문에 영상의 국지적 특성을 고려해야 한다. 본 연구에서는 Hyperion 영상을 대상으로 하였으며, 자료구조 기법 중 하나인 Quadtree와 이용하여 노이즈 밴드를 추출하였다. Quadtree 구조로 분할된 영역의 프랙탈 차원을 계산하고 프랙탈 차원의 분산을 이용하였다. Hyperion 영상에 존재하는 노이즈 종류 중 무작위 노이즈를 포함하고 있는 밴드 추출에 초점을 맞추었으며, 시각적으로 판단하여 작성한 참조자료와 비교하였다. 제안된 알고리즘 적용 결과 무작위 노이즈가 포함된 밴드 대부분이 추출되었으며, 영상에 관계없이 30개 이상의 노이즈 밴드를 제거할 수 있음을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.269-286
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• 2018

Signal detection in symmetric alpha-stable ($S{\alpha}S$) distributed noise is a challenging problem. This paper proposes a detector based on a decreasing exponential function (DEF). The DEF detector can effectively suppress the impulsive noise and achieve good performance in the presence of $S{\alpha}S$ noise. The analytical expressions of the detection and false alarm probabilities of the DEF detector are derived, and the parameter optimization for the detector is discussed. A performance analysis shows that the DEF detector has much lower computational complexity than the Gaussian kernelized energy detector (GKED), and it performs better than the latter in $S{\alpha}S$ noise with small characteristic exponent values. In addition, the DEF detector outperforms the fractional lower order moment (FLOM)-based detector in $S{\alpha}S$ noise for most characteristic exponent values with the same order of magnitude of computational complexity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.588-595
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• 2014

In this paper, analysis of the vibration Characteristic for the Mine Detectable Test Platform is described. The test platform system is the multi-sensor mine detectable vehicle. This multi-sensor mine detectable unit is more efficient detection performance than other conventional methods. The test platform system has five subsystems, the UWB(Ultra Wide Band) sensor scanner, the MD(Metal Detector) sensor scanner, the neutron sensor scanner, and the detectable vehicle. We perform the vibration tests for the test platform and analyze the vibration characteristic, such as the max displacement, the max deformation and the max Von-Misses Stress.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.440-445
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• 2011

Dynamic characteristic analysis is required in developing SMT mounter system with high installation speed and position precision, because of vibration source occurred by positioning head. This paper presents the method of improving dynamic characteristic of SMT(Surface Mount Technology) mounter with finite element method and modal test. The design direction is that natural frequencies of SMT mounter must be higher than the vibration source. In addition, the effect of input shaping on residual vibration reduction is investigated by simulating the response of a first-order system.

• 한국소음진동공학회논문집
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• 제24권12호
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• pp.927-934
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• 2014

In this paper, analysis of the vibration characteristic for the mine detectable test platform is described. The test platform system is the multi-sensor mine detectable vehicle. This multi-sensor mine detectable unit is more efficient detection performance than other conventional methods. The test platform system has five subsystems, the UWB(ultra wide band) sensor scanner, the MD(metal detector) sensor scanner, the ND(neutron detector) sensor scanner, and the detectable vehicle. We perform the vibration tests for the test platform and analyze the vibration characteristic, such as the max displacement, the max deformation and the max Von-Misses stress.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1394-1399
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• 2001

The purpose of this paper is that investigates the dynamic behavior characteristic of W.T.S(Wind Turbine System) and carries out the evaluation analysis during operating W.T.S. To investigate the dynamic behavior characteristic of W.T.S. the experiments to measure vibration of the blade from the attached accelerometer on the flap and edge section of the blade that is one of the most important elements of dynamic characteristic of W.T.S are performed. Natural frequency and mode shape are calculated with commercial program (STAR MODAL) using the measured vibration acceleration that receives the signal with F.F.T Analyzer from the accelerometer. For validation of these experiments. the finite element analysis is performed with commercial F.E.M Program (ANSYS) on the basis of the natural frequency and mode shape. The results indicate that experimental values have good agreements with the finite element analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1347-1352
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• 2001

In this study, the acoustic properties of polyester sound absorbing materials with three different bulk densities were investigated by calculating and measuring the acoustic parameters in terms of characteristic impedance, propagation constant, and absorption coefficient. For the calculations, Delany and Bazley's empirical equation was used together with the experimentally obtained specific flow resistivities under steady flow conditions. For the experimental measurements, the well-known two-thickness method was accessed. The experimentally measured values of characteristic impedance and propagation constant were generally agreed well with the corresponding calculated values. Based on the comparisons between the calculations and measurements, it was found that the magnitude of the absorption coefficient was closely related to the characteristic impedance and the real part of the propagation constant. Especially, the maximum magnitude of the absorption coefficient was depended upon the imaginary part of the propagation constant indicating the phase change of the propagation constant.

• 한국전자파학회논문지
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• 제24권2호
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• pp.152-160
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• 2013

본 연구에서는 동시 스위칭에 의한 잡음 저감을 위하여 일반적으로 사용하는 비드와 더불어 나선형 공진기를 함께 사용하여 보다 향상된 광대역의 잡음 저감 특성을 확보하였다. 비드는 기본체배 주파수 아래 대역인 0.8 GHz 이내에서 효과적으로 잡음이 저감되고, 공진기는 공진기 턴 길이에 반비례한 공진 주파수 이내까지 잡음을 잘 저감할 수 있었다. 이것을 바탕으로 비드와 공진기를 함께 사용하면 각 주파수 영역에서 임피던스가 높은 성분에 의하여 영향을 받아 보다 광대역의 동시 스위칭에 의한 잡음 저감 특성을 얻을 수 있다. 22 nH 비드만을 사용한 경우 1, 2, 3, 그리고 4체배에서 각각 4.8, 2.0, 0, 0.6 dB의 노이즈 저감 특성을 얻었으나, 22 nH의 비드와 3턴 공진기를 함께 사용할 경우 9.5, 8.3, 6.1, 9.9 dB의 광대역에 걸친 잡음 감소 특성을 얻을 수 있었다. 비드가 없는 경우와 비교하여 22 nH 비드를 사용하면 전원단 흔들림이 76 mV에서 56 mV로 감소하고, 비드와 3턴 공진기를 함께 사용하면 34 mV로 감소함을 볼 수 있다. 즉, 비드와 공진기를 동시에 사용함으로써 보다 광대역의 동시 스위칭에 의한 잡음 저감 특성을 확보함을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.854-855
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• 2015

Electric machines for office automation device such as printer and scanner have been required the low noise and vibration performance. Many researches about the low noise and vibration of polygon mirror scanner motor have been also progressed. The noise and vibration of polygon mirror scanner motor can be classified by aerodynamic, structural and electromagnetic. Electromagnetic noise and vibration can be occurred by high cogging torque and nonsinusoidal back EMF. To improve the cogging torque and back EMF characteristic, we apply unequal air-gap. To analyse characteristic of a polygon mirror scanner motor, two dimensional finite element method is used. To minimize the cogging torque of a polygon mirror motor, Kriging based on latin hypercube sampling (LHS) is utilized. As a result, the cogging torque and torque ripple improved while maintaining the back EMF and average torque.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.904-908
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• 2008

As the various industrial production machinery has come into being by development of industrial technology, the productivity of the basic industrial production machinery has improved and the international competitiveness of the one of Korea has strengthened. However, at the same time, noise from various industrial production machinery disturbs the quiet environment. There are 35 kinds of the noise emission machinery defined in the noise and vibration control act according to the horse power and the number of machinery. These were classified in 1992 through investigation from 1990 to 1991, and the characteristic of the noise emission machinery may be different from the past one. So we need to investigate the characteristics of the noise emitted by machinery to control it rightly. Also we need to investigate the new noise emission machinery which has come into being recently. In this survey, we measured sound intensity of 32 noise emission machinery to calculate the sound power levels of those and investigated the characteristic of the sound power level of those according to the frequency. From the survey, we found that the forging machine, concrete pipe and pile making machine, sawing machine, etc. are the noisy machinery. And the automatic packing machine, sewing machine, centrifuge, etc. are the silent machinery. Also the generator, the concrete pipe and pile making machine, the printing machine, etc. emit the low frequency noise, and the molding machine, the stone cutter, the metal cutter, etc. emit the high frequency noise. Lastly, we intented to propose the proper guide line of classifying noise emission machinery.