• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.449-453
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• 2001

In this paper, we propose an algorithm to design the adaptive structure of wavelet neural network with F-projection and geometric growing criterion. Geometric growing criterion consists of estimated error criterion considering local error and angle criterion which attempts to assign a wavelet function that is nearly orthogonal to all other existing wavelet functions. These criteria provide a methodology that a network designer can construct wavelet neural network according to one's intention. We apply the proposed constructing algorithm of the adaptive structure of wavelet neural network to approximation problems of 1-D and 2-D function, and evaluate the effectiveness of the proposed algorithm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.21-28
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• 2007

Using multi-resolution, the mutiresolution proportional-integral-derivative(MRPID) controller functions as a filter to eliminate noise and disturbance which are included in error signals. If the sampling frequency is high, the response time will be delayed because of the remaining high frequency component although the overshoot is removed. However, if the sampling frequency is low, the response time will be enhanced by getting rid of signal components while the overshoot is increased. In this paper, the sampling frequency tuning method is used the response of the proportional integral derivative(PID) controller and the MRPID controller, and the parameter tuning method is considered the characteristic of the MRPID controller. The proposal method is verified by computer simulations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.1024-1031
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• 2000

The plate waves propagating in thin plates have dispersive nature showing the dependence of velocities on the frequency. Wavelet transform (WT) using Gabor function can be used to analyze the dispersive waves in the time-frequency domain, and then to find the arrival time of the waves propagating in the plate. Plate waves in the aluminum plate of 3 mm thickness were identified and generated by pencil lead breaks and the lowest order symmetric ($S_o$) and antisymmetric ($A_o$) modes were analyzed by the WT method. The measured group velocities agreed very well with theoretical predictions in the frequency range of 50-400 kHz. The pencil breaks were also used to simulate acoustic emission sources in the plate, and the source location algorithm using the wavelet transform of dispersive plate waves was found to give accurate results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.44-49
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• 2002

In recent years, diagnostic techniques have been investigated to detect a partial discharge(PD) in a high voltage electrical equipment. Because PD signal is very sensitive and difficult to suppress strong noises such as narrow-band radio frequency noise and random noise, the accuracy and credibility of PD measurement might be influenced by surrounding interference. Using the technique of PD detection by electromagnetic wave, we have studied the characteristics of both PD and substation-in interference signal. Also, we propose a wavelet packet transform based technique to perform a feature extraction from the interference and PD signal and a classification of the extracted features. The results show that time-frequency characteristics between PD and interference can be obviously distinguished. It is helpful for the development of the insulation diagnosis technique.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.257-262
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• 2004

본 논문에서는 초음파 웨이브렛 지연시간을 이용한 초고온 온도 측정법을 기초로 하여, 이 기술을 바탕으로 두 번째 단계인 용융물 온도에서 내구성을 갖는 초음파 센서(UTS : Ultrasonic Temperature Sense)를 설계하여 약 $2300^{\circ}C$까지 실험로 내부의 온도를 측정하고자 한다. 이때 UTS 설계의 중요 인수는 센서 봉 외부 표면과 시스(sheath) 내부 표면의 두 텅스텐 재료가 비접촉 상태로 요구된다. 만약 이들 두 재료가 고온의 상태에서 접촉되면 음향적 분로인 Shunting 현상이 발생한다. 이 현상을 물리적으로 억제하기 위한 센서 설계가 필요하게 되며, 이 센서 설계의 성공 여부의 첫째 요구 조건으로서 센서 내부의 구조적으로 음향 Shunting 현상을 억제하는 기술이 필요로 하게 된다. 이들 센서의 내부 구조에 상호 접촉을 피하기 위해서 작은 공간에 새롭게 구조적 분리가 가능한 텅스텐 재료인 Standoff를 제작하여 설치하였다. 그러나 본 실험에서는 제안된 Standoff적용한 출력 신호의 신호 대 잡음 비는 소량의 개선 가능성을 확인하였으나, 다양한 Standoff의 설계와 제작이 지속적으로 진행되어야 할 것이다.

• Journal of Korea Multimedia Society
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• v.8 no.4
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• pp.482-491
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• 2005

In this paper, we proposed the microcalcification detection algorithm which is based on wavelet transform and automatic thresholding method in the X-ray mammographic images. Digital X-ray imaging system is essential equipment in the field diagnosis and is widely used in the various fields such as chest, fracture of a bone, and dental correction. Especially, digital X-ray mammographic imaging is known as the most important method to diagnose the breast cancer, many researches to develop the imaging system are processing in country. In this paper, we proposed a microcalcifications detection algorithm necessary in the early phase of breast cancer diagnosis and showed that a algorithm could effectively detect microcalfication and could aid diagnosis-radiologist.

• Journal of the Korea Computer Industry Society
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• v.2 no.8
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• pp.1117-1122
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• 2001

Recently, issues on the internet searching of image information through various multimedia databases have drawn an tremendous attention and several researches on image information retrieval methods are on progress. By incorporating wavelet transform and correlation matrixes, we propose a novel and highly efficient feature vector extraction algorithm that has an capability of a robust similarity matching. The simulation results have yielded a faster and highly accurate candidate image retrieval performance in comparison to those of the conventional algorithms. Such an improved performance can be obtained because the used feature vectors were compressed to 256：1 while the correlation matrixes are incorporated to provide a fuel information for the better matching.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1471-1477
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• 2006

Electrocorticogram (ECoG) was recorded in one young adult suffering from medically refractory partial seizures a few weeks before resection. ECoG of intractable focal epilepsy was analyzed usins AR model, wavelet analysis and cross-correlation analysis. The cross-correlation of the epileptic discharges was calculated between the electrodes in every unit of time, to get the phase shift. A contour map of the phase shift and the sequential two-dimensional phase shift maps were utilized to localize the epileptic foci and to study their propagation process. More than two epileptogenic foci were localized and two kinds of propagating process were shown. These investigations suggest that epileptic phenomena can be caused by at least two kinds of mechanisms in one patient.

• The Journal of Information Technology
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• v.10 no.3
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• pp.15-31
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• 2007

Region-of-Interest is the region within the image selected for the users needs. The development of multimedia has made the expectation of image telecommunication higher, but the usage of the image, image transmission time, and image storage create problems. When transmitter or the receiver stops transmission at some point, we can still see the general image and the ROI maintains better image quality if the ROI is specified beforehand. In this paper, three methods are proposed and constructed for the transmission of ROI. In the first method, the ROI and the background are separated and then encoded as described above. The second method is to encode without separating the ROI and the background. The masked region is scaled and the coefficients are increased, then the region is transmitted first. The third method is the loseless coding of the ROI. For loseless coding, real number tap cannot be restored perfectly due to the rounding error, so the method of using integers is used. The proposed method shows a better performance than EZW even in case of ROI's PSNR at quality of 40 dB.

• Journal of KSNVE
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• v.9 no.4
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• pp.841-848
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• 1999

In the quality assurance check process of DC motor systems, even though the overall sound pressure level is acceptable, there is an incident that subjective evaluation leads to failure in product quality due to annoying noise. This kind of problem may be originated from the manufacturing or assembly process. In this paper, the transient spectral analysis, or the time-frequency analysis is applied to the noise quality problem. For the case study, the cause of annoying noise in the wind shield wiper motor is experimentally analyzed in detail. It is concluded that the defect in the shaft causes the impact noise which is not detectable by steady spectral analysis. Also demonstrated is how the time-frequency analysis is effectively applied to the annoying noise identification of the rotor-gear system.