• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1929-1931
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• 1996

In this work, it is proposed new PD(partial discharge) detection technique using electro-optic effect, for which partial discharges generated from needle-plane electrode in air were detected through optical measuring system by use of $LiNbO3_3$ electro-optic crystal. As a result, it is noticed that PD measurable phase intervals are limited by the asymmetrical D-E hysteresis loop of the crystal with defects and half-wave voltage. However, both number of measured PD pulses and their amplitude were increased with applied voltage, which likely implies that it is possible to detect PD through newly proposed electro-optic method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
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• pp.183-186
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• 2002

It is well known that a discharge in oil is the source of various physical and chemical phenomena. One of them is ultra-sonic wave, and its detection is a useful method to the diagnosis of the transformer insulation condition. Conventionally, ultra-sonic waves are detected by Piezo-electric trans-ducer(PZT), and we use optical method that has many advantages. In this paper, we constructed a Mach-Zehnder interferometer with optical fiber and investigated the principle of operation. Test of the ultrasonic-detecting ability was performed for both of PZT and fiber-optic sensor. Discharge test arrangement is based on the needle-plane electrode system in oil and applied AC high voltage. Ultrasonic waves were detected and showed time-delay characteristics. We analyzed the data with frequency domain and wavelet transform.

• 핵의학기술
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• 제14권2호
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• pp.181-185
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• 2010

갑상선암 환자의 경부 림프절에서 미세침흡인생검술(fine needle aspiration biopsy, FNAB)을 시행하며 얻은 미세침세척액의 티로글로불린(thyroglobulin, Tg)측정법의 진단적 성적과 유용성을 알아보고자 FNAB 세포검사의 결과와 비교하였다. 갑상선암의 경부림프절 전이가 의심되어 초음파 시행한 총 37명의 환자 48개의 FNAB 검체를 대상으로 하였고, 수술 후 조직검사결과 또는 장기간 영상 추적검사를 기준으로 하여 세포검사와 미세침세척액 티로글로불린(FNAB-Tg)측정법을 비교하여, 각 검사의 특이도, 민감도 및 정확도를 평가하였다. 추가적으로 Tg-항체가 양성일때 FNAB-Tg 검사에는 어떠한 영향을 미치는지 Tg-항체 검사를 같이 시행한 34명을 대상으로 분석하여 보았다. FNAB 검체의 세포검사에서 전이 음성인 36개 검체 중 35개 검체에서 음성을 보였고, 전이 양성인 12개 검체 중 9개 검체에서 양성을 보였다. FNAB-Tg측정법의 경우 전이 음성인 36개의 검체 중 32개의 검체에서 음성을 보였고, 전이 양성인 12개의 검체 중 12개 검체 모두 양성을 보였다. 따라서 세포검사의 민감도와 특이도는 각각 75.0% (9/12)와 97.2% (35/36)였고, 위음성이 25% (3/12)였다. 반면에 FNAB-Tg 측정법의 민감도와 특이도는 각각 100% (12/12)와 88.9% (32/36)였고, 위양성이 11.1% (4/36)였다. 정확도는 두 검사 모두 91.7% (44/48)였다. Tg-항체에 대한 검사 결과를 얻을 수 있는 34명을 따로 분석한 결과, Tg-항체의 존재 유무가 FNAB-Tg 측정법의 진단 성능에 영향을 주지 않음을 확인할 수 있었다. FNAB 검체를 이용한 세포검사는 특이도가 높고 반면, FNAB-Tg 측정법은 민감도가 높은 검사임을 확인할 수 있었다. 따라서 림프절 전이가 의심되는 갑상선환자에서 FNAB를 시행할 때 세포검사와 FNAB-Tg 측정법은 동시에 시행되어야 할 상호보완적인 검사들이다.

• 대한기관식도과학회지
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• 제5권1호
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• pp.7-13
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• 1999

Background and Objective： The tuberculous lymphadenitis of neck is one of the most common extra-pulmonary tuberculosis in Korea. Although the incidence of pulmonary tuberculo-sis has decreased recently, that of cervical tuberculous lymphadenitis has not decreased. In spite of great efforts and diversity of study, the exact criterias of diagnosis and optimal therapeutic methods of cervical tuberculous lymphadenitis have been the subject of much debate and still remain unclear. So we intend to enucleate clinical manifestations and suggest the optimal therapeutic manners. Material : The 483 cases, diagnosed as cervical tuberculous lymphadenitis by fine needle aspiration biopsy during the past 10 years from Jan. 1987 to Dec. 1996 Method : Retrospective study Results 1) The overall rate of tuberculous cervical lymphadenitis was 23.4% of neck mass. 2) Incidence ratio of male to female was 1：2.7 3) The frequent location of tuberculous lymphadenitis was posterior cervical area, supraclavicular area, jugular chain in order. 4) The response rate of medical treatment in tuberculous cervical lymphadenitis was 84.9%. 5) The duration of medical treatment in remissioned group was 18.6 months in average. 6) Surgical intervention was needed in 15.1%. 7) The duration of post operative medical treatment was 18.4 months in average. Conclusion : Tuberculous cervical lymphadenitis is prevalent in women, age of 20-40 years and mainly involve posterior cervical area. Fine needle aspiration biopsy is a very useful method for early detection of cervical tuberculous lymphadenitis. After diagnosis is made, anti-tuberculosis medication is recommended for more than 18 months. Unless the size of neck mass is decreases inspite of the thorough anti-tuberculosis medication for more than 1 month or if complication like as abscess or fistula occurs, surgery is needed with post operative medical treatment for more than 12 months.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권1호
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• pp.44-51
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• 2000

In this paper, using a wide-band AE sensor with the frequency range from 100[kHz] to 1.5[kHz], the frequency spectra of AE signals generated from the corona discharges of the needle-plane gap and from the partial discharges of an epoxy void were analyzed to determine the proper ultrasonic sensor with optimum frequency range according to the patterns of corona discharges. We also examined the propagation characteristics of AE signals in oil and the relationship between the magnitude of corona discharge and the magnitude of AE signals in peak-to-peak value under the application of 60[Hz] ac high-voltage. From these results, the main frequency spectra of AE signals emitted from the corona discharges of the needle-plane gap were about 130[kHz] by the fast fourier transform, but the main frequency spectra appeared to be 230[kHz] in the partial discharges of an epoxy void. The magnitude of AE signals was proportional to the magnitude of corona discharge and discharge current pulse with increasing the applied voltages.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.907-911
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• 2007

This paper dealt with the frequency spectrum analysis of acoustic signal produced by partial discharge (PD) in insulation oil and the positioning of PD occurrence to apply in diagnosis of oil insulated transformers. Three types of electrode system ; the needle-plane, the plane-plane, and the wire-wire structure were assembled to simulate partial discharges in oil insulated transformers. A low-noise amplifier and a decoupling circuit were designed to detect acoustic signal with high sensitivity The frequency spectrum of the acoustic signal were 50 kHz ${\sim}$ 260 kHz in the needle-plane, 50 kHz ${\sim}$ 250 kHz in the plane-plane, and 45 kHz${\sim}$195 kHz in the wire-wire electrode system. Their peak frequencies were 145 kHz, 130 kHz and 114 kHz, respectively The position of PD occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission (AE) sensors, and we could find the position within the error of 1 % in the experimental apparatus.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.247-252
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• 1999

In this paper, in order to investigate availability of the OW-PD measurement method which has been proposed as an alternative of AC-PD measurement method to an after laying test and/or diagnosis for the power cable system, partial discharges owing to the needle-type defect integrated into the cable have been measured using AC and OW(Oscillating Wave) voltages. In the AC-PD measurement, the magnitude, phase and pulse number of partial discharges have been changed with the duration of voltage application, which can be analyzed through the relation with the process of the electrical tree initiation and propagation. In addition, the characteristics of partial discharges using OW voltage are appeared to be similar to those in case of AC-PD measurement and to be different with the shapes of electrical tree. From these results, it is concluded that the OW-PD measurement method is available to the tests for the cable system.

• 한국전기전자재료학회논문지
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• 제23권1호
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• pp.53-60
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• 2010

This paper dealt with the acoustic detection of partial discharge (PD) in insulation oil for insulation diagnostics of oil immersed transformers. Electrode systems such as needle to plane, plane to plane, and floating were fabricated to simulate some defects in transformers. A wide band acoustic emission(AE) sensor with the frequency ranges of 100 kHz~1 MHz and a narrow band AE sensor with the resonant frequency of 140 kHz were used in the experiment. Also, a decoupler and an amplifier were designed to detect and amplify the acoustic signal only. The decoupler separates acoustic signal from DC source without any distortion, and the amplifier has the gain of 40 dB in frequency ranges of 11 kHz~4 MHz. In the experiment, frequency components and propagation characteristics of acoustic signal were analyzed, and an algorithm of positioning of PD occurrence by the time difference of arrival was proposed. From the results, the frequency components of the acoustic signal exist from 50 kHz to 200 kHz and the positioning error of PD calculated by three AE sensors was within 1%.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.546.1-546
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• 2003

Laser doppler flowmeter (LDF) has been applied to the measurement of pulpal blood flow (PBF) in human teeth. As far as we searched, the detection area of the pulp in the blood flow measurement has not been clarified, yet. Therefore, the purpose of this study was to obtain information of the detection area in PBF measurement using LDF. The experiments were performed on the artificial blood circulation in extracted human upper central incisors. The apical portions of examined teeth (n=6) were severed and root canals were enlarged from the apical end to the 2mm incisal to the level of enamel-cement junction. An individual resin cap of each tooth was prepared and a hole was drilled 2mm incisal to enamel-cement junction of the labial side of the cap. The measurement probe of LDF (MBF3D, Moor Instrument, UK) was plugged into the hole of the cap. Heparinized human peripheral blood, which was in advance collected and diluted 3 times with physiological saline, was pumped through the apical foramen of the teeth via a silicone tube and a disposable needle (o.d. 0.7mm) and blood flow signals were monitored. The flux signal significantly increased with the enlargement of the root canal to incisal direction (p<0.01, Friedman analysis). The result indicates that the performance of LDF in PBF with human teeth is limited.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.84-88
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• 2008

The roller bearings play an important role not only sustain radial or axial load of system, but carry out a rotatory movement as a various operating conditions. They happen that incipient faults which were caused by excessive load, manufacturing or assembling process's errors and many other reasons are created. The bearing faults make noise and vibration by a continuous collision of rotatory components, which can lower the quality and stability of auto-transmission. Therefore, it is important to detect the early fault as soon as possible. This paper presents a detecting method for the improvement in quality by developing the program which can be used to analyze and predict the vibrational characteristics caused by roller bearing faults. We completed development of the inspection system of vibration by appling the most efficient detecting methods and verified the system's reliability through experiments.