• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
• /
• pp.970-972
• /
• 1998

In practice, there may be various defects in an insulating system, so that the PD signals can be produces from these defect simultaneously. Regarding these situations, we have to discriminate the type of defect as well as to determine whether the PD occurs or not. In our research. some analysis results of the PD signals from multi-defects insulating system will be presented. We measure the PD signals using three kind of electrode system: IEC(b). Needle-Plane and mixed electrodes. To simulate multi-defect systems, we combine two electrode systems and apply test voltage simultaneously. Neural network, statistical analysis methods will be tested, and the possibilities and limitations of each method will be clarified.

• Journal of Chest Surgery
• /
• 제27권3호
• /
• pp.234-237
• /
• 1994

We report a case of double orifice mitral valve complicating a partial atrioventricular septal defect.The preoperative diagnosis was suggested by a characteristic angiographic and echocardiographic findings but the correct diagnosis of double orifice mitral valve itself was proven by open heart surgery. The smaller accessory mitral orifice was located in the left lateral leaflet and was left untouched. The A-V septal defect was closed with Gore-Tex patch and localized tricuspid annuloplasty was done using Gore-Tex tubular graft for correction of severe tricuspid regurgitation. The anterior mitral cleft left intact had mild mitral regurgitation on postoperative echocardiography.Postoperative course was uneventful and the patient was discharged 2 weeks later.

• Bulletin of the Korean Chemical Society
• /
• 제23권7호
• /
• pp.971-984
• /
• 2002

The multichannel quantum defect theory (MQDT) is reformulated into the form of the configuration mixing (CM) method using the geometrical construction of the S matrix developed for the system involving two open and one closed channels. The reformulation is done by the phase renormalization method of Giusti-Suzor and Fano. The rather unconventional short-range reactance matrix K whose diagonal elements are not zero is obtained though the Lu-Fano plot becomes symmetrical. The reformulation of MQDT yields the partial cross section formulas analogous to Fano's resonance formula, which has not easily been available in other's work.

• Journal of Chest Surgery
• /
• 제33권2호
• /
• pp.183-185
• /
• 2000

With the marked decrease in operative mortality in simple heart diseases there have been several reports on the minimally invasive and cosmetic techniques including submammary incision right parasternal approach right anterolateral thoracotomy partial sternotomy and subxiphoid approach. We report here subxiphoid approach without sternotomy for the repair of atrial septal defect as the procedure that has less invasive technique and more cosmetic effect.

• 한국세라믹학회지
• /
• 제27권7호
• /
• pp.841-850
• /
• 1990

The electrical conductivity of SrTiO3 thick films, which has been prepared by screen printing and sintering on polycrystalline Al2O3 substrates, was determined as a function of oxygen partial pressure and temperature. The data showed that electrical conductivity was proportional to the -1/4th power of the oxygen partial pressure for the oxygen partial pressure range from 10-4-10-8 to 10-20 atm and proportional to Po2+1/4 for the oxygen partial pressure range from 10-6-10-4 to 1atm. And then n-p transition region of electrical conductivity moved to lower oxygen partial pressure region as the sintering temperature of thick film specimens increased under about 140$0^{\circ}C$. These data were consistent with the presence of small amounts of acceptor impurities in SrTiO3 thick film which have been diffused from Al2O3 substrate in the range of solid solubility limit.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1659-1661
• /
• 2003

Recently, diagnostic techniques have been investigated to defect a partial discharge in high voltage electrical equipment. We have studied the characteristics of the acoustic partial discharge originating from the electrical defects in cubicle GIS(C-GIS). An acoustic emission(AE) sensor is used on the enclosure to detect partial discharge source because the sensor is sensitive to stress waves in its frequency range that may not be from a partial discharge source. AE signal is analyzed with phase-magnitude-frequency number(${\Phi}$-V-n) and pulse per second(PPS). Experience result has shown that the omitted acoustic signal has phase dependency and phase shift characteristic according to increase with applied voltage. These result will be helpful to the pattern recognition of the acoustic partial discharge in a C-GIS.

• 한국전기전자재료학회논문지
• /
• 제22권10호
• /
• pp.879-883
• /
• 2009

This paper was provided to help in detecting defects in power transformer. For this purpose, a partial discharge cell was designed and manufactured as a discharge source to simulate particle defected paper-oil insulation in power transformer. Experimental set-up for measuring PD signals was described. Magnitude of electromagnetic wave signals and corresponding amount of apparent discharge were measured simultaneously against phase of applied voltage to the discharge cell. Frequency range and pattern of PRPD(Phase Resolved Partial Discharge) of partial discharge signals were examined and analyzed. The results will be contributed to build the defect database of power transformer and to decrease the substation faults.

• Journal of information and communication convergence engineering
• /
• 제21권3호
• /
• pp.233-238
• /
• 2023

This study presents a method for identifying partial discharge defects in an eco-friendly gas insulated system using a backpropagation algorithm. Four partial discharge (PD) electrode systems, namely, a free-moving particle, protrusion on the conductor, protrusion on the enclosure, and voids, were designed to simulate PD defects that can occur during the operation of eco-friendly gas-insulated switchgear. The PD signals were measured using an ultrahigh-frequency sensor as a nonconventional method based on IEC 62478. To identify the types of PD defects, the PD parameters of single PD pulses in the time and frequency domains and the phase-resolved partial discharge patterns were extracted, and a back-propagation algorithm in the artificial neural network was designed using a virtual instrument based on LabVIEW. The backpropagation algorithm proposed in this paper has an accuracy rate of over 90% for identifying the types of PD defects, and the result is expected to be used as a reference database for asset management and maintenance work for eco-friendly gas-insulated power equipment.

• Journal of Chest Surgery
• /
• 제40권10호
• /
• pp.719-721
• /
• 2007

심낭 결손증은 드문 선천성 기형으로 대부분의 경우 증상이 없이 우연히 발견되지만, 심장의 일부가 탈장되어 흉통 등의 증상을 나타내는 경우도 있다. 본 증례는 14세 여자 환자가 내원 3개월 전부터 발생한 운동 시 호흡곤란과 가슴 통증을 주소로 내원하여 부분 심낭 결손을 통한 좌심방 부속지의 탈장(herniation)이 진단되어 수술적 치료를 시행하여 보고하는 바이다.

• Journal of Chest Surgery
• /
• 제20권1호
• /
• pp.106-111
• /
• 1987

Twenty eight patients with atrial septal defect operated on from May, 1983, to July, 1986 at the Department of Thoracic and Cardiovascular Surgery, Chungnam National University Hospital, were analyzed retrospectively. Among the 28 patients of atrial septal defect, 8 were male and 20 were female. Their ages ranged from 4.6 years to 52.5 years old with the mean of 15.3 years. The main clinical symptoms on admission were exertional dyspnea [82%], frequent respiratory infection [75%], palpitation [54%] and easy fatigability [25%]. Electrocardiographic findings were as follows: Regular sinus rhythm [100%], RVH [54%], RBBB [25%] and first degree of A-V block [4%]. Hemodynamic studies were performed in all cases and mean pulmonary systolic arterial pressure was 34.1*11.8mmHg. and mean Qp/Qs was 2.6*0.9. All 28 patients were operated under direct vision using extracorporeal circulation. 23 cases were secundum type defect and a single hole was found in 22 cases. The associated cardiovascular anomalies were found in 11 patients: ventricular septal defect in 3, patent ductus arteriosus in 1, partial anomalous pulmonary venous drainage in 2, mitral regurgitation in 2, tricuspid regurgitation in 1, anomalous left atrial septation in 1 and valvular pulmonary stenosis in 1. The defect closed directly in 22 cases and with patches in 6 cases. Postoperative complications were wound infection, arrhythmia bleeding, intracardiac patch detachment, pneumothorax and urethral injury. But there was no operative mortality.