• Journal of Power Electronics
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• 제13권2호
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• pp.232-242
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• 2013

To obtain phase currents information in AC drives, shunt sensing technology is known to show great performance in cost-effectiveness and therefore it is widely used in low cost applications. However, shunt sensing methods are unable to acquire phase currents in certain operation conditions. This paper deals with the derivation of the boundary conditions for phase current reconstruction in three-shunt sensing inverters and proposes a voltage injection method to expand the measurable areas. As the boundary conditions are deeply dependent on the switching patterns, they are typically analyzed on the voltage vector plane for space vector pulse width modulation (SVPWM) and discontinuous pulse width modulation (DPWM). In the proposed method, the voltage injection and its compensation are conducted within one sampling period. This guarantees fast current reconstruction and the injected voltage is decided so as to minimize the current ripple. In addition to the voltage injection method, a sampling point shifting method is also introduced to improve the boundary conditions. Simulation and experimental results are presented to verify the boundary condition derivation and the effectiveness of the proposed voltage injection method.

• 전자공학회논문지
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• 제49권9호
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• pp.35-42
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• 2012

개구면 결합 급전 방법을 이용하여 inductive loaded 마이크로스트립 패치 안테나를 설계하고 병렬 스터브를 이용하여 임피던스 대역폭을 넓히는 방법에 대해 연구하였다. 급전선로에 병렬 스터브를 삽입하여 AIMPA의 임피던스 대역폭을 확장시켰다. 병렬 스터브를 삽입한 AIMPA의 -10 dB 임피던스 대역폭은 5.51 %로 병렬 스터브를 삽입하지 않은 AIMPA의 임피던스 대역폭 2.4 %와 비교하여 대역폭이 약 129.6 % 증가함을 볼 수 있었다. -10 dB 대역폭 내에서 방사 패턴의 전체적인 모양은 크게 변화하지 않음을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2249-2251
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• 1997

Total 144 quadrupole magnets are installed in PLS. The magnets are connected in series with groups of two or 24. Each group is powered by a high-precision constant-current DC power supply. For the purpose of the beam based alignment of beam position monitors in the PLS, it is necessary to adjust the current of each quadrupole independently. To achieve this, a high current shunt regulator is designed. It can shunt a maximum 50 A of the quadrupole magnet current. The shunt regulator is programmable and the current amplitude can be varied linearly with a 12-bit resolution. Power transistors are used in the current shunt regulator. The operation of transistors is in linear region. The RS232C protocol is used for remote control and status report of the shunt regulator to the main control centre of the PLS. Preliminary result indicates that the calibration accuracy of the beam position monitor can be achievable in less than $10{\mu}m$.

• Journal of Chest Surgery
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• 제50권3호
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• pp.215-219
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• 2017

Pulmonary arteriovenous fistula (PAVF) is a complication of the Glenn shunt. A 57-year-old tetralogy of Fallot (TOF) patient, who had undergone a Glenn shunt and TOF total correction, complained of dyspnea and cyanosis. PAVFs were present in the rig ht lung, and rig ht lung perfusion was nearly absent. After coil embolization, takedown of the Glenn shunt, and reconstruction of the rig ht pulmonary artery, the patient's symptoms were relieved. Extrapulmonary radioisotope uptake caused by the PAVFs shown in lung perfusion scans decreased, and right lung perfusion increased gradually. Although the development and resolution of PAVFs after a Glenn shunt have been reported in the pediatric population, this may be the first report on this change in old age.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.1-12
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• 2002

In this study, a passive suppression scheme for nonlinear flutter problem of composite panel, which is believed to be more reliable than the active control methods in practical operations, is proposed. This scheme utilizes a piezoelectric inductor-resistor series shunt circuit. The finite element equations of motion for an electromechanically coupled system is derived by applying the Hamilton\\`s principle. The aerodynamic theory adopted for the present study is based on the quasi-steady piston theory, and von-barman nonlinear strain-displacement relation is also applied. The passive suppression results for nonlinear panel flutter are obtained in the time domain using the Newmark-$\beta$ method. To achieve the best damping effect, optimal shape and location of fille piezoceramic (PZT) patches are determined by using genetic algorithms. The effects of passive suppression are investigated by employing in turn one shunt circuit and two independent shunt circuits. Feasibility studies show that two independent inductor-resistor shunt circuits suppresses flutter more effectively than a single shunt circuit. The results clearly demonstrate that the passive damping scheme that uses piezoelectric shunt circuit can effectively attenuate the flutter.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• 대한핵의학회지
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• 제19권2호
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• pp.93-95
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• 1985

A simple imaging procedure has been devised for patients with peritoneo-venous shunts when ascites reaccumulates and a decision must be made on whether or not to revise the shunt. We recently experienced a patient with reaccumulated ascites in whom obstruction of peritoneo-venous shunt was suspected. 5 mCi of $^{99m}Tc-phytate$ was injected into the peritoneal cavity and imaging of the abdomen was performed $1\sim30$ minutes later. With a proper funtioning shunt, radioactivity in the liver and spleen were easily identifiable in this case. If the shunt is obstructed, tracer activity will remain in the peritoneal cavity and thus can not be identifiable in the liver or spleen. Conclusively, radionuclide methods might be very useful for evaluation of peritoneo-venous shunt patency.

• Journal of Chest Surgery
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• 제25권1호
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• pp.23-31
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• 1992

The ideal approach in the staged management of patients with pulmonary atresia has been a challenging problem and the result has not been always satisfactory. We reviewed our early result of initial palliative surgeries in fifteen cases of pulmonary atresia with interventricular communication Included are eight cases of simple pulmonary atresia with ventricular septal defect and seven cases of pulmonary atresia associated with other complex cardiac anomalies. The ages of the patients were less than one year except one. The morphology of pulmonary vasculature was highly variable and showed unfavorable conditions in most cases. Pulmonary artery was nonconfluent in two. Two-thirds of all cases showed significant problems such as juxtaductal stenosis or diffuse hypoplasia. The ductus arteriosus usually narrowed at its pulmonic end. Initial palliation was done by modified Blalock-Taussig shunt in six, central shunt with or without pulmonary angioplasty in five, right ventricular outflow tract [RVOT] reconstruction in three and direct connection of nonconfluent pulmonary arteries with bilateral cav-opulmonary shunt in one patient. There were 3 hospital deaths. Two of them underwent simultaneous repair of the associated anomaly of TAPVR. Among the six patients who received modified Blalock-Taussig shunt, three needed early second palliative procedure by central shunt, RVOT patch reconstruction and pulmonary angioplasty in each case, All patients who received central shunt showed marked clinical improvement. Among the twelve patients who survived the palliative procedures, two patients underwent total correction 13 months and 18 months after initial palliation respectively. We think that the choice of palliative procedure must be individualized according to the morphology of the pulmonary arteries. More experience and long term follow-up data are necessary to meet this challenging problem.

• Journal of Chest Surgery
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• 제21권1호
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• pp.136-142
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• 1988

Between February, 1983, and March, 1987, thirty-one systemic-pulmonary shunts were performed in 28 patients with cyanotic congenital heart disease. Age ranged from 8 months to 28 years [mean age, 5.4 years, Weight ranged from 7 kg to 48 kg [mean weight, 16kg]. There were 4 classic Blalock-Taussig shunts, 5 central polytetrafluoroethylene shunts, 1 aorta-right pulmonary artery shunt with graft, and 21 modified Blalock-Taussig shunts. One patient required another shunt immediately due to insufficient pulmonary blood flow with patent graft. There was no postoperative death. Conduit diameters included 4mm [2 cases], 5 mm [22 cases], and 6 mm [3 cases]. Long term follow up was available in 27 patients [96.4%] with mean period of 20 months [range, 4 months to 49 months]. The effectiveness of shunt was evaluated by cardiac catheterization with angiography [15 patients] or clinically. They showed improvement of systemic oxygen saturation values by 12% and decrease of hemoglobin by 2.3gm/dl [P<0.01]. There were 2 shunt occlusion in central shunts at 32 and 48 months respectively, and one narrowing of graft in modified Blalock-Taussig shunt at 12 months. The patency rate was 91.6% at 24 months for 5 mm grafts in modified Blalock-Taussig shunt.

• Journal of Chest Surgery
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• 제39권11호
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• pp.861-863
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• 2006

우리는 만성 신부전 환자에서 혈액투석을 위한 상완동맥-두정맥단락술(brachiocephalic arteriovenous shunt)을 시행한 후 최근 빠르게 성장하는 아주 거대한 정맥의 동맥류 1예를 경험하였기에 보고하는 바이다. 환자는 48세 남자로 7년 전 본원에서 동정맥단락술을 시행한 후 혈액투석을 해왔으나 좌측 상완의 정맥을 따라 점점 성장하는 정맥의 동맥류와 박동성 통증으로 혈액투석을 지속할 수 없었다. 내원 1개월 전 혈액투석을 지속하기 위해 타 의료기관에서 우측 손목관절부에 새로운 동정맥루를 조성하여 혈액 투석을 하고 있었다. 동정맥류가 너무 거대하여 동정맥단락 재건술은 시도하지 않았으며 수술은 전신마취하에서 동정맥루를 결찰하고 확장된 정맥의 동맥류를 모두 제거하였다. 환자의 술 후 경과는 양호하였다.