• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.333-342
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• 2005

This paper proposes a method, which recognizes student's identification card by using image processing and recognition technology and can manage student information on the web. The presented scheme sets up an average brightness as a threshold, based on the brightest Pixel and the least bright one for the source image of the ID card. It is converting to binary image, applies a horizontal histogram, and extracts student number through its location. And, it removes the noise of the student number region by the mode smoothing with 3$\times$3 mask. After removing noise from the student number region, each number is extracted using vertical histogram and normalized. Using the enhanced ART1 algorithm recognized the extracted student number region. In this study, we propose the enhanced ART1 algorithm different from the conventional ART1 algorithm by the dynamical establishment of the vigilance parameter. which shows a tolerance limit of unbalance between voluntary and stored patterns for clustering. The Experiment results showed that the recognition rate of the proposed ART1 algorithm was improved much more than that of the conventional ART1 algorithm. So, we develop an educational matters administration system by using the proposed recognition method of the student's identification card.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.3
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• pp.119-125
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• 2012

Caliper intergrated Electric Parking Brake (EPB) is an automatic parking brake system, attached to rear caliper. Because EPB uses luxury vehicles recently, the drivers of vehicles are sensitive to the EPB noise. EPB is operated by the motor and gear, so noise is generated by motor and gear. In order to reduce noise, One of EPB manufacturers uses helical gear and changes the shape of EPB housing. But these methods are not optimized for reduction of interior noise. There are many noise transfer paths into vehicle interior and it is difficult to identify the noise sources. Therefore, in this study, we performed contribution analysis and modal testing in the vehicle system. It is possible to distinguish between air-borne noise and structure-borne noise in the vehicle interior noise by comparing interior noise peak with resonance mode map.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.641-645
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• 2008

In this paper, vibration sources of the BLOC motor are identified and the motor vibrations are reduced by structural modification. For vibration characteristic identification, vibration signals measured by an accelerometer when the BLOC motor is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the motor speed. It is found that main vibration source is BLOC motor test rig. From finite element analyses and some experiments, it is also found that resonances occur because the natural frequencies of the test rig exist in usual driving speed rang. To shift the natural frequencies outside the driving rang, the test rig is modified increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.3-8
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• 1990

소음/진동 문제를 해결하는 데 있어서 우선은 소음/진동원들의 위치를 알아 내고 그들 중에 비중이 가장 큰 소음/진동원을 파악하는 것이 중요하다. 다 입력/단일출력 모형을 이용한 소음/진동원 규명에 대한 방법에는 주파수 응 답함수를 이용하는 방법(frequency response function approach)과 부분 기여 도 함수(partial coherence function)를 이용하는 방법 등이 있는데, 입력들 사이의 상호상관(correlation)이 없는 경우에는 전자의 방법을 사용하여 출력 에 가장 큰 비중을 차지하는 소음/진동원을 알아낼 수 있으나 상호상관이 존 재하는 경우에는 후자의 방법을 사용하게 된다. 그러나 후자의 방법을 적용 함에 있어서도 기본적으로 소음/진동원들의 위치를 알아야 하는 것 이외에 그들 사이의 원인.효과관계(causaling), 또는 우선순위(rank)를 우선적으로 아 는 것이 중요한데 이는 입력들 사이의 우선순위를 어떻게 두느냐에 따라 해 석 결과가 다르게 나타나기 때문이다 [1,2,3]. 본 연구에서는 부분 기여도 함 수를 이용하여 소음/진동원을 규명할 때 그들 사이의 우선순위를 결정하는 방법을 제시하고 2입력/1출력 모형에 대해 적용하여 보았다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.187-191
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• 1990

그동안 실험을 통해 측정된 울산화력 BFP 진동 Data의 분석을 통하여 문제 가 되는 과도진동원에 대한 분석이 시도되었다. BFP의 이력과 그간의 측정 자료를 근거로 진동원과 진동에너지의 전달 경로를 가정하였고 각각의 진동 원에 대한 타당성 검토를 위하여 신호처리가 수행되었으며 그 결과로부터 BFP 과도진동 현상에 의해 야기되는 F 베어링 92.5 Hz의 진동에너지는 Voith Coupling의 기어에서 발생되었던 것으로 밝혀졌다. 문제의 해결을 위 해 치차를 대체시켰으며 진동값은 치차가 교환되기 전의 193.$\mu$m이 40.$\mu$m 이하로 줄 수 있었고 따라서 BFP는 안전운행 조건을 만족시키는 동급(Fair Operation)에 들게 됨을 볼 수 있다. BFP로부터 분리된 구동축 Gear는 육안상 크게 균열은 없어 보였으나 특정방향으로 일부 마모가 있어 보였으며 이는 유체와의 회전시 Unbalance에 의한 마모결과로 보여진다. 현 재 6-2 BFP에서 사용되었던 구동측 부품인 기어, Impellar는 치차마모등 비 파괴 정밀조사와 함께 Wet Balancing등의 측정이 진행되고 있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.789-794
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• 2008

The damage identification in a flexible system requires modal informations which is represented by FRF(Frequency response function) or modal parameters. In this paper, energy isoclines are introduced to access the prediction of fatigue damage on a flexible component exposed mainly to the exciting source rather than external forces. After deriving the concerned function, energy isoclines, from the investigation of the relationship between energy and damage, its practical application is explained by the simple uni-axial excitation test for the notched round bar.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.728-733
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• 2006

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. In particular, the HVAC sound among the vehicle interior noise has been reflected sensitively in the side of psychology. In previous study, we have developed to verify identification of source for the vehicle HVAC system through multiple-dimensional spectral analysis. Also we carried out objective assessments on the vehicle HVAC noises and subjective assessments have been already performed with 30 subjects. In this study, the linear regression models were obtained for the subjective evaluation and the sound quality metrics. The regression procedure also allows you to produce diagnostic statistics to evaluate the regression estimates including appropriation and accuracy. Appropriation of regression model is necessary to $R^2$ value and F-value. And testing for regression model is necessary to independence, homoscedesticity and normality. Also we selected optimum layout of damping material using Taguchi method. As a result of application, sound quality is improved more quietly, powerfully, even though costly, and smoothly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.327-332
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• 2004

Leak noise is a good source to identify the exact location of a leak point of underground water pipelines. Water leak generates broadband noise from a leak location and can be propagated to both directions of water pipes. This sound propagation due to leak in water pipelines is not a non-dispersive wave any more because of the surrounding pipes and soil. However, the necessity of long-range detection of this leak location makes to identify low-frequency acoustic waves rather than high frequency ones. Acoustic wave propagation coupled with surrounding boundaries including cast iron pipes is theoretically analyzed and the wave velocity was confirmed with experiment. The leak locations were identified both by the acoustic emission (AE) method and the cross-correlation method. In a short-range distance, both the AE method and cross-correlation method are effective to detect leak position. However, the detection for a long-range distance required a lower frequency range accelerometers only because higher frequency waves were attenuated very quickly with the increase of propagation paths. Two algorithms for the cross-correlation function were suggested, and a long-range detection has been achieved at real underground water pipelines longer than loom.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.269-274
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• 2022

An artificial neural network (ANN) that identifies radionuclides from low-count gamma spectra of a NaI scintillator is proposed. The ANN was trained and tested using simulated spectra. 14 target nuclides were considered corresponding to the requisite radionuclide library of a radionuclide identification device mentioned in IEC 62327-2017. The network shows an average identification accuracy of 98.63% on the validation dataset, with the gross counts in each spectrum N_c = 100~10000 and the signal to noise ratio SNR = 0.05-1. Most of the false predictions come from nuclides with low branching ratio and/or similar decay energies. If the N_c>1000 and SNR>0.3, which is defined as the minimum identifiable condition, the averaged identification accuracy is 99.87%. Even when the source and the detector are covered with lead bricks and the response function of the detector thus varies, the ANN which was trained using non-shielding spectra still shows high accuracy as long as the minimum identifiable condition is satisfied. Among all the considered nuclides, only the identification accuracy of ²³⁵U is seriously affected by the shielding. Identification of other nuclides shows high accuracy even the shielding condition is changed, which indicates that the ANN has good generalization performance.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.708-718
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• 2002

In this paper, the problems in identifying the noise sources by using the sound intensity technique are dealt with for the general radiated near-field from vibro-acoustic sources. For this purpose, a three-dimensional model structure resembling the engine room of a car or heavy equipment is considered. Similar to the practical situations, the model contains many mutually coherent and incoherent noise sources distributed on the complicated surfaces. The sources are located on the narrow, connected, reflecting planes constructed with rigid boxes, of which a small clearance exists between the whole box structure and the reflecting bottom. The acoustic boundary element method is employed to calculate the acoustic intensity at the near-field surfaces and interior spaces. The effects of relative source phases, frequencies, and locations are investigated, from which the results are illustrated by the contour map, vector plot, and energy streamlines. It is clearly observed that the application of sound intensity technique to the reactive or reverberant field, e.g., scanning over the upper engine room as is usually practiced, can yield the detection of fake sources. For the precise result for such a field, the field reactivity should be checked a priori and the proper effort should be directed to reduce or improve the reactivity of sound field.