• Journal of Korean Neurosurgical Society
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• 제29권2호
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• pp.274-279
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• 2000

A 35-year-old female patient who had been paraplegic since her upper thoracic cord injury one and a half years before was presented with a syringomyelia involving C7 to T2 cord segments on follow-up magnetic resonance imaging(MRI). Her pain on the chest and bilateral axilla worsened since about 2 years after initial injury, and MRI demonstrated a progressively enlarging cystic syrinx cavity of the cervicothoracic cord. The posttraumatic syringomyelia was managed operatively by lysis of the arachnoid adhesions, myelotomy, and expansile duraplasty. Post-operatively her pain was relieved, and MRI showed decrease in size of the syrinx, and digital infrared thermographic imaging(DITI) showed diminution of the hyperthermic area on the anterior chest. In conclusion, the posttraumatic syringomyelia can be managed successfully without shunt operation. It seems apparent that expansile duraplasty is effective in controlling the posttraumatic syrinx.

• Journal of Chest Surgery
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• 제32권8호
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• pp.749-752
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• 1999

최근 여러 병원에서 선천성 수정대혈관전위의 해부학적 교정이 보고되고 있다. 해부학적 교정을 받은 수 정대혈관전위 환아의 단기 및 장기추적에서 문제가 되는 것은 주로 심방전환수술에 따르는 대정맥과 심방 문합 부\ulcorner의 협착과 상심실성 부정맥이며 이는 심방이 작은 경우에 위험도가 증가되고 특히 심첨과 대정맥 이 동측에 있는 경우에는 문제가 된다. 이런 경우 이중전환수술시 일부 선택된 환아에서 대정맥폐동맥단락 술을 추가함으로써 수술의 위험성과 심방의 잠재성 합병증을 피할 수 있다고 여겨진다. 본원에서는 수정대 혈관전위, 심실중격결손, 폐동맥폐쇄가 있으면서 심첨과 대정맥이 동측에 있는 환아의 해부학적 교정시에 대 정맥폐동맥단락술을 추가하여 좋은 결과를 얻었기에 보고하는 바이다.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.320-329
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• 2012

The Load Tap Changing (LTC) transformer and Shunt Capacitor (SC) bank are major devices for voltage and reactive power control in a distribution substation. Thus, the coordination operation of a LTC transformer and a SC bank is required to achieve better voltage and reactive power compensation at a distribution substation in the same time. This paper proposes coordinate control method of LTC transformer and SC bank to achieve better voltage and reactive power compensation and operation times of these two devices in the same time. The mathematical formulations of the proposed coordinate control method are introduced. Sample case studies are shown to verify the effectiveness of the proposed coordinate control method.

• Journal of Power Electronics
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• 제10권4호
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• pp.419-427
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• 2010

A parallel control strategy in capacity proportion frequency allocation mode for shunt active power filters (APFs) is proposed to overcome some of the difficulties in high power applications. To improve the compensation accuracy and overall system stability, an improved selective harmonic current control based on multiple synchronous rotating reference coordinates is presented in a single APF unit, which approximately implements zero steady-state error compensation. The combined decoupling strategy is proposed and theoretically analyzed to simplify selective harmonic current control. Improved selective harmonic current control forms the basis for multi-APF parallel operation. Therefore, a parallel control strategy is proposed to realize a proper optimization so that the APFs with a larger capacity compensate more harmonic current and the ones with a smaller capacity compensate less harmonic current, which is very practical for accurate harmonic current compensation and stable grid operation in high power applications. This is verified by experimental results. The total harmonic distortion (THD) is reduced from 29% to 2.7% for a typical uncontrolled rectifier load with a resistor and an inductor in a laboratory platform.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.237_238
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• 2009

This paper proposes coordinative control method between STATCOM installed within substation and other reactive power resources including Shunt Reactors and Shunt Capacitors and OLTC. Voltage/Reactive power control has various difficult aspects to control because of analysis and system dynamics error. This coordinative control method suggests practical algorithm regarding system voltage and reactive power status which is easy to implement in substation basis. In normal status, STATCOM-Shunts-OLTC are in operation. The proposed algorithm is tested and verified in EMTP/RV. And this is expected to be applied to control multiple reactive power devices combined with SCADA/EMS system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1496-1498
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• 1999

The line charging is becoming larger due to the expansion of underground cable and extra high voltage lines. It causes reactive power surplus at light load condition which may force generators to operate reluctantly in the under excited mode. This paper proposes the pratical criteria and methodolgy for the shunt reactor planning while suppressing generator's under excited operation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1204-1209
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• 2000

Many analytical and experimental studies on the active suppression of nonlinear panel flutter by using piezoceramic patch have been carried out. However, these active control methods have a few important problems; a large amount of power is required to operate actuators, and additional apparatuses such as sensor systems and controller are needed. In this study passive suppression schemes for nonlinear flutter of composite panel, which is believed to be more robust suppression system than active control in practical operation, are proposed by using piezoelectric inductor-resistor series shunt circuit. Toward the end, a finite element equation of motion for an electromechanically coupled system is proposed using the Hamilton's principle. To achieve the best damping effect, optimal shape and location of the piezoceramic(PZT) patches are determined by using genetic algorithms. The results clearly demonstrate that the passive damping scheme by using piezoelectric shunt circuit can effectively attenuate the flutter.

• Journal of Chest Surgery
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• 제33권3호
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• pp.257-261
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• 2000

Pulmonary arteriovenous fistula can occur in a variety of clinical situations including liver diseases, infections, metastatic carcinomas, systemic disorders, and after the palliation of congenital heart diseases. A 72-day-old male infant with Tetralogy of Fallot and pulmonary atresia underwent surgical correction without difficulty. However, ventilator weaning in the ICU failed initially because of an unexplained postoperative hypoxemia(FiO2: 0.8, PaO2: 40 mmHg, SaO2: 80∼90%). Postoperative follow-up lung perfusin scan at postoperative 15 days showed right-to-left shunt(33.6%) and ventilator weaning was performed on the 20th day after the operation (FiO2: 0.4, PaO2, 50mmHg, SaO2: 86.9%). Arterial oxygen saturation under room air was 80∼85% at 7 months postoperatively. One and half year follow-up lung perfusion scan showed decreased amount of right-to-left shunt (11.2%). We report a case with a review of the literatures.

• Journal of Power Electronics
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• 제13권4호
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• pp.692-700
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• 2013

This paper discusses the design of a novel synchronous reference frame (SRF) method that can extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous SRF studies, the proposed method has an innovative feature that does not require a fictitious current signal. Other key features of the proposed strategy include frequency-independent operation, accurate reference current extraction, and relatively fast transient response. The effectiveness of the proposed method is investigated by conducting a detailed mathematical analysis. Results of the analysis confirm the superior performance of the suggested approach. Theoretical evaluations are confirmed by the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1647-1649
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• 1998

This paper describes the power frequency voltage and its countermeasure when a 765 kV transmission line is directly connected to a 345 kV line and operated at 345 kV voltage. The summary of this result is as follows : The western route of 765 kV transmission line doesn't need any countermeasure to reduce the power frequency voltage at the receiving end. The eastern route of 765 kV transmission needs 100 Mvar(3 phase) capacity of shunt reactor at the receiving end to reduce the power frequency voltage. The use of shunt reactors in the 765 kV transmission lines has unexpected problems, one of which is induction of high voltages on a de-energized circuit of two parallel lines. This paper examined the problem of resonance on two parallel transmission circuits in one routes.