• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.111-114
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• 2008

The existence of noise bands may deform the typical shape of the spectrum, making the accuracy of clustering degraded. This paper proposes a statistical approach to remove noise bands in hyperspectral data using the correlation coefficient of bands as an indicator. Considering each band as a random variable, two adjacent signal bands in hyperspectral data are highly correlative. On the contrary, existence of a noise band will produce a low correlation. For clustering, the unsupervised ${\kappa}$-nearest neighbor clustering method is implemented in accordance with three well-accepted spectral matching measures, namely ED, SAM and SID. Furthermore, this paper proposes a hierarchical scheme of combining those measures. Finally, a separability assessment based on the between-class and the within-class scatter matrices is followed to evaluate the applicability of the proposed noise band removal method. Also, the paper brings out a comparison for spectral matching measures.

• 제어로봇시스템학회논문지
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• 제19권11호
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• pp.974-978
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• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. AVI systems usually report different measurements on the same defect with some variations on position or rotation mainly because different images are provided. This is caused by possible variations from the image acquisition process including optical factors, nonuniform illumination, random noises, and so on. For this reason, conventional area based defect measuring methods have problems of robustness and consistency. In this paper, we propose a new defect size measuring method to overcome this problem, utilizing volume information that is completely ignored in the area based defect measuring method. The results show that our proposed method dramatically improves the robustness and consistency of defect size measurement.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.303-303
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• 2000

It is difficult to determine the static axle weight of a vehicle with weigh-in-motion systems which in absence measure instantaneous axle impact forces. The difficulty in determining a static axle weight results from dynamic effects induced by vehicle/road interactions. One method to improve the problem is to quantify a statistical confidence level for measured axle weight. The quarter-car model is used to simulate vehicle motion, Also, the road input to vehicle model can be characterized in statistical terms by PSD (power spectral density) of appropriate amplitude and frequency contents other than an exact spatial distribution. The confidence levels for the measured axle weight can be obtained by the random process analysis using both vehicle model and road input.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.351-356
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• 2011

Some materials show the character of rigid body in low frequency spectrum. The rigid body motions are consisted of translational and rotational motions. Especially, we can get the acceleration or displacement of a random point in the rigid body by analyzing rigid body transfer matrix at the car's engine and power train. Actually it is difficult to measure the acceleration by attaching the sensor inside of the engine and power train. So the hard to predict acceleration data can be achieved attaching the sensor on the outside of the engine and power train by analyzing the data of rigid body motion which the engine is operated using dynamo. Also this paper will show the change of predicted data and accuracy variation by not using all the measured data but a few exceptions of the point number.

• 한국통신학회논문지
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• 제22권1호
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• pp.151-161
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• 1997

In this paper we designed a high speed wireless multiple access protocol, which is suitable for future multimedia wireless LAN systems which support high quality video teleconferencing, telephony and graphic databases. In the proposed protocol, Slotted-ALOHA protocol is used for transmitting random data packets and the packet reservation multiple access(PRMA) protocol for transmitting periodic data packets. The use of minislot is introduced for the reservation scheme. In order to measure the performance characteristic of the proposed protocol, a simulator is designed using an object oriented programming language, C++, and an exhaustive simulation study is carried out. From the simulation results, it is observed that the proposed protocol and the existing PRMA protocol have almost the same delay characteristic when network traffic is low. However, the proposed protocol is superior to the PRMA protocol when traffic becomes higher. The proposed protocol and the results can be utilized for the design of the wireless access systems and future broadband wireless LANs.

• 소음진동
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• 제10권6호
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• pp.941-948
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• 2000

Active noise control is an approach to reduce the noise by utilizing a secondary noise source that destructively interferes with the unwanted noise. In general, active noise control systems rely on multiple sensors to measure the unwanted noise field and the effect of the cancellation. This paper develops an approach that utilizes a single sensor. The noise field is modeled as a stochastic process, and an adaptive algorithm is used to adaptively estimate the parameters of the process. Based on these parameter estimates, a canceling signal is generated. Oppenheim assumed that transfer function characteristics from the canceling source to the error sensor is only a propagation delay. This paper proposes a modified Oppenheim algorithm by considering transfer characteristics of speaker-path-sensor This transfer characteristics is adaptively cancelled by the proposed adaptive modeling technique. Feasibility of the proposed method is proved by computer simulations with artificially generated random noises and sine wave noise. The details of the proposed architecture. and theoretical simulation of the noise cancellation system for three dimension enclosure are presented in the Paper.

• 한국소음진동공학회논문집
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• 제17권10호
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• pp.918-922
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• 2007

Most of the study on system identification has been carried out using input/output relation in physical domain. However identification concept of stochastic system has not been reported up to now. Interest is focused to identify an unknown dynamic system under random external disturbances which is not possible to measure. A concept to identify the system parameters in stochastic domain is proposed and implemented in terms of simulation. Attempt has been made to identify the system parameters in inverse manner in stochastic domain based on system output only. Simulation is conducted to reveal quite noticeable performance of the proposed concept.

• 방송공학회논문지
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• 제10권2호
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• pp.149-155
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• 2005

We have proposed an objective evaluation method using ESNR as the measure of approximation by the visual model, which coincides with MOS, a subjective evaluation method. For two-value images, we have used five kinds of modulation methods: 1) ordered dither, 2) least mean error, 3) pulse density low division, 4) simple two-value, and 5) random dither methods. The purpose of this paper is to investigate the validity of ESNR, by comparing the proposed method together with the existing representative methods such as PSNR and WSNR, with the subjective method MOS. The results of a series of experiments show that the ranking by MOS coincides with ESNR, though does not coincides with PSNR and WSNR.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.145-149
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• 2005

We describe holographic ROM system to read bit-type data. It has optical system similar to general optical data storage system such as DVD. But because holographic data storage systems have to adopt imaging optical system, in our system bit-type data can be read out by different servos with DVD. We devised 3-hole method similar to 3- beam method for the tracking servo and used astigmatic optical system for the focusing servo. Also we developed the reference beam servo to measure movement of reference beam because especially holographic data storage systems need reference beam. The system was operated by these three servos and objective lens of NA 0.6. We obtained eye pattern from random data of 3T-2um track pitch. We also obtained another eye pattern from DVD disk by only using focusing servo PDIC in our system to verify the compatibility with DVD.

• 전기의세계
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• 제18권1호
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• pp.15-23
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• 1969

A lot of recent researches have shown that a Pseudo Random Binary Signal is a quite effective test signal to measure the impulse response of a plant. Generally speaking, however, such a response itself is not satisfactory to determine the appropriate control parameters or control inputs. Here, the author intends to estimate the unknown parameters of the First Order Plant with Dead Time by means of correlation method using M-sequence signal. The time constant T and the dead time L of the plant are eatimated with one tracking loop by automatically adjusting delay time .tau. of M-sequence signal according to variations of T and L. In this paper, a three level M-sequence signal is used as a test signal in order to avoid troublesome operations to calculate partial derivatives of a given performance index with respect to the parameters which are usually required in the Model Method. Several experiments with analogue computer using low pass filters as averaging circuits showed good results as expected.