• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.394-399
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• 2012

In recent years, MEMS sensors show huge attraction in machine condition monitoring, which have advantages in power, size, cost, mobility and flexibility. They can integrate with smart sensors and MEMS sensors are batch product. So the prices are cheap. And the suitability of it for condition monitoring is researched by experimental study. This paper presents a comparative study and performance test of classification of MEMS sensors in target machine fault classification by 3 intelligent classifiers. We attempt to signal validation of MEMS sensor accuracy and reliability and performance comparisons of classifiers are conducted. MEMS accelerometer and MEMS current sensors are employed for experiment test. In addition, a simple feature extraction and cross validation methods were applied to make sure MEMS sensors availabilities. The result of application is good for using fault classification.

• The Journal of the Acoustical Society of Korea
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• v.31 no.5
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• pp.298-308
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• 2012

This study was designed to examine the phoneme recognition errors of hearing-impaired (HI) listeners on a consonant-by-consonant basis, to show (1) how each HI ear perceives individual consonants differently and (2) how standard clinical measurements (i.e., using a tone and word) fail to predict these differences. Sixteen English consonant-vowel (CV) syllables of six signal-to-noise ratios in speech-weighted noise were presented at the most comfortable level for ears with mild-to-moderate sensorineural hearing loss. The findings were as follows: (1) individual HI listeners with a symmetrical pure-tone threshold showed different consonant-loss profiles (CLPs) (i.e., over a set of the 16 English consonants, the likelihood of misperceiving each consonant) in right and left ears. (2) A similar result was found across subjects. Paired ears of different HI individuals with identical pure-tone threshold presented different CLPs in one ear to the other. (3) Paired HI ears having the same averaged consonant score demonstrated completely different CLPs. We conclude that the standard clinical measurements are limited in their ability to predict the extent to which speech perception is degraded in HI ears, and thus they are a necessary, but not a sufficient measurement for HI speech perception. This suggests that the CV measurement would be a useful clinical tool.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.175-178
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• 1996

The purpose of this thesis is the propose of various signal processing algorithm for the ECG(electrocardiogram) and the design of realtime automated ECG analyzer feasible with these algorithms. The algorithms are composed of (1)filtering procedure fer the estimation and removal of baseline drift, 60Hz power line interference, and muscle artifacts (2)detection procedure of QRS complex and P wave (3)typification procedure for the pattern classification according to the morphologies (4) selection of representative beat, significant point and wave boundary decision procedure and (5) parameter extraction and diagnosis procedure. All verifications are carried out between the algorithms proposed in this paper and other algorithms already proposed by many researchers, for the objective comparison in each procedure. The efficiency of proposed algorithms are demonstrated with the aid of internationally validated CSE database and the performances of filtering procedure are compared on artificial noise signal as well as actual ECG signals with appropriate noise components. for the comparison on the performance of designed automated ECG analyzer, the diagnosis results were compared with ECG analyzer manufactered by Fukuda denshi in Japan.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.714-720
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• 2016

Rubbing and misalignment are the most usual faults that occurs in rotating machinery and with them severe effect on power plant availability. Especially blade rubbing is hard to detect on FFT spectrum using the vibration signal. In this paper, the possibility of feature analysis of vibration signal is confirmed under blade rubbing and misalignment condition. And the lab-scale rotor test device provides the blade rubbing and shaft misalignment modes. Feature selection based on GA (genetic algorithm) is processed by the extracted feature of the time domain. Then, classification of the features is analyzed by using SVM (support vector machine) which is one of the machine learning algorithm. The results of features selection based on GA compared with those based on PCA (principal component analysis). According to the results, the possibility of feature analysis is confirmed. Therefore, blade rubbing and shaft misalignment can be diagnosed by feature of vibration signal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.75-78
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• 2001

Recently, the HFPD measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Also HFPD testing is able to offer the judgement standard of degradation level of HV machine and can detect discharge signals in live-line. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2658-2660
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• 2005

This paper presents a stator winding fault diagnosis technique of induction motor on the PC - based virtual instrumentation system designed using the graphical programming language LabVIEW. This method collects the 3-phase current signals using the current probe amplifier and PXI/DAQ system then the preprocessing removes the noise using LPF, after then this method transforms the stator current to Park's vector and obtains the each Park's Vector pattern and detects stator winding fault by comparing the obtained faulted pattern with the healthy pattern. This proposed LabVIEW based diagnosis system is applied to the 3 phase 1 hp induction motor and obtained the reasonable results under no load condition. The test results give us the possibility a simple and realistic on-line winding fault diagnosis system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.50-54
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• 2000

Recently, the HFPD measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Also HFPD testing is able to offer the judgement standard of degradation level of HV machine and can detect discharge signals in live-line. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.132-135
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• 2004

In generally, compared with VHF band, electromagnetic waves of UHF band have a low influence for external noise. We can detect the real abnormality with several pC in GIS using UHF method. Recently, it has applied to use the external UHF sensor attached on spacer to GIS of existing substation. In this paper, we firstly described the technique of the partial discharge measurement using frequency analysis and phase analysis in UHF band. Secondly, we presented the results of sensitivity, the relationship of dBm-pC and diagnosis of the reason of PD source by phase analysis. And then, we report the diagnosis result of partial discharge on 800kV GIS in domestic substation. rge diagnosis of GIS.

• Journal of Oral Medicine and Pain
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• v.18 no.2
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• pp.29-41
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• 1993

A prevalence study was carried out on 847 CMD patients who had visited the Department of Oral Medicine in Pusan National University from 1990 to 1993. To obtain the same type of information, all subjects were interviewed and examined clinically using a standardized examination form, The ratio of women to men was about 3:1 and all subjects were divided into acute and chronic groups on the basis of 6 months of duration. Diagnostic groups consisted of muscle disorder, joint disorder and muscle-joint disorder. As related to gender, duration and diagnosis subjective and objective symptoms in CMD were studied. The obtained results were as follows : 1. Muscle-joint disorder had the highest percent, followed by muscle disorder and joint disorder. 2. The most common reasons for CMD treatment were pain, joint noise and limited opening, while headache and neckache were relatively often reported as associated symptoms and dizziness, ringing in the ears also reported as secondary CNS excitatory effects. 3. Pain was more ofter seen in women, acute group and muscle-related disorder groups (p<0.05, p<0.01). Noise was significantly frequent in chronic group and joint-related groups (p<0.01). 4. Analysis of contributing factors presented that macrotrauma was found frequently in men (p<0.05), and that muscle-related groups were more related to stress than joint disorder grop (p<0.05). 5. Hard end feel was seen significantly often in joint-related disorder group (p<0.05). On the other hand, soft end feel was frequent in muscle disorder. 6. Reciprocal clicks and crepitation increased with chronicity. Subjects with joint-related disorder groups significantly often reported all kinds of noises (p<0.01). 7. Tender muscles and joints were more often reported in women and chronic group. Whereas muscle-related disorder groups revealed significantly more tender muscles (p<0.01). joint-related disorder groups presented significantly more tender joints (p<0.01).

• Journal of Oral Medicine and Pain
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• v.16 no.1
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• pp.85-93
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• 1991

In this study, 88 dental students were examined to evaluate the relationship between occlusal states and TM disorders for the epidemiologic study of TM disorders. The clinical evaluation were composed of mandibular movement, TMJ noise, occlusal states and muscle palpation. The following results were disclosed. 1. The frequencies of pain on mandibular movement were 3.4% on maximum opening, 1.13% on protrusion and no pain on laterotrusion. 2. The frequencies on TMJ sound were 21.6% in click, 1.13% in crepitus. 3. The frequency of tenderness on palpation was 12.5% on extra oral, intraoral and neck muscles, tenderness on palpation of TMJ capsule were reported 5 cases, and 4 of them were female. 4. The distribution of Angle's classification was found 79.5% in class I, 4.5% in clasII-div.1 and 15.9% in class III. There was no significant differences on TM disorders between Angles classifications. 5. There was no significant differences on TM disorders between the subjects of canine guided occlusion and group function occlusion, and also for the differences between the subjects of nonworking side interferences and no interferences on laterotrusion. 6. There was no significant differences on TM disorders between the subjects of anterior teeth trauma in C.C. and no anterior teeth trauma, but there were significant differences between the subjects of posterior protrusive contact and no posterior protrusive contact.