• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.343-347
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• 1999

YBCO film을 이용한 meander 형태의 저항형 한류기에서 고장이 발생하였을 때 초기의 과도상태에서 볼수 있는 첨두전류를 억제하기 위하여 shunt 저항을 병렬로 취부한 경우의 전기적특성을 살펴보았다. 인가전압을 16.5 V$_{peak}$로 가하고 R$_0$는 1 ${\omega}$,R$_L$을 7.7 ${\omega}$으로 하고 shunt 저항을 5 ${\omega}$으로 하였을 때 약 12.2 A$_{peak}$의 전류값에서 최초quench가 발생하였으며 초전도 한류소자에 quench 발생으로 인한 저항이 발생함과 동시에 I$_1$으로 흐르던 사고전류의 일부가 shunt 저항이있는 I$_2$으로 서서히 분로하여 첨두전류가 거의 발생하지 않았다. 이때 초전도 한류기를 적용하지 않은 경우 최대 사고전류는 약 16.5 A$_{peak}$이었으며 초전도 한류기를 적용한 경우는 최대 한류전류값이 9 A$_{peak}$에서 4주기후에는 5.8 A$_{peak}$이었다. 인가전압 V$_0$=113 V$_{peak}$이고 표준저항 R$_0$는 1${\omega}$, 그리고 R$_L$을 7.7 ${\omega}$으로 하고 shunt 저항을 5 ${\omega}$으로 하였을 때 사고각 0 $^{\circ}$에서 사고전류값이 최고 23.0 A$_{peak}$까지 상승하고 이후 일정한 값을 유지하였다. 일반적으로 사고발생 직후에는 전류변화율에 의하여 전류값의 급격한 상승을 보이지만 shunt 저항이 전류분류의 역할을 수행하여 첨두전류는 거의 발생하지 않았다. 또한 상온의 gold층의 저항을 감안했을 때 사고발생후 약 36msec 후에 상온에 도달하였으며 shunt 저항이 없는 경우의 11 msec에 비하여 약 3배이상 길어졌다. 사고각 45 $^{\circ}$와 90 $^{\circ}$인 경우는 반복실험에 의한 시편의 특성저하(degradation)에 의하여 정상상태에서 초전도체에 흐르는 전류가 약간 발생하였다. 계통의 신뢰성이 중요한 요소로 작용하는 실제운전에서는 시편의 특성저하에 의한 quench전류의 감소를 감안하여 적절한 운전조건을 도출하여야 한다. 이상에서 앞으로는 장기간의 실제운전 조건을 고려하여 시편의 특성저하(degradation)와 가혹조건에 대한 전기적 특성에 대한 연구를 병행하고자 한다.

• 한국임상수의학회지
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• 제20권4호
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• pp.508-515
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• 2003

A 4-month-old 5.7 kg male Golden retriever with history of seizure, depression, lethargy and anorexia was referred to Veterinary Medical Teaching Hospital, Chungbuk National University. Hematologic examination revealed microcytosis and nonregenerative anemia. Serum chemical values showed increased serum ammonia (423 $\mu$mol/L), ALP (1101 U/L), r-GTP (13.9 U/L) and CPK (1454 U/L), and decreased total protein (4.9 g/dl) and BUN (1.6 mg/dl). Microhepatia was shown in survey abdominal radiographs. Color doppler ultrasonographic examination revealed dilated tortuous vein with turbulent flow within liver parenchyma. Intraoperative jejunoportography and intraoperative ultrasonography confirmed the location and size of single intrahepatic shunt vessel in the left medial liver lobe. Also, the anomalous vessel entering the caudal vena cava was identified beneath the diaphragm. The shunting vessel was ligated with using an Ameroid constrictor. General conditions, hematologic and serum chemical values resolved gradually after surgery. One month after surgery abdominal radiograph showed normal gastric axis and it was consistent whit the normal size liver. Normal echogenecity of liver and enlargement of portal vein were shown in ultrasonography. It is assumed that survey radiography and ultrasonography are useful for diagnosis of single intrahepatic shunt in a dog and especially jejunoportography vein portography and intraoperative ultrasonography are suitable for confirmation of the anatomic location and size of the shunting vessels.

• International Journal of Aeronautical and Space Sciences
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• 제7권1호
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• pp.54-64
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• 2006

To augment weakly damped lag mode stability of a hingeless helicopter rotor blade in hover, piezoelectric shunt with a resistor and an inductor circuits for passive damping has been studied. A shunted piezoceramics bonded to a flexure of rotor blade converts mechanical strain energy to electrical charge energy which is dissipated through the resistor in the R-L series shunt circuit. Because the fundamental lag mode frequency of a soft-in-plane hingeless helicopter rotor blade is generally about 0.7/rev, the design frequency of the blade system with flexure sets to be so. Experimentally, the measured lag mode frequency is 0.7227/rev under the short circuit condition. Therefore the suppression mode of this passive damping vibration absorber is adjusted to 0.7227/rev. As a result of damping enhancement using passive control, the passive damper which consists of a piezoelectric material and shunt circuits has a stabilizing effect on inherently weakly damped lag mode of the rotor blades, at the optimum tuning and resistor condition.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.30-40
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• 2015

For a shunt power quality controller (SPQC) the DC side voltage value which is closely related to the compensation performance is a significant parameter. Buy so far, very little discussion has been conducted on this in a quantitative manner by previous publications. In this paper, a method to design the DC side voltage of SPQC is presented according to the compensation performance in the single-phase system and the three-phase system respectively. First, for the reactive current and the harmonic current compensation, a required minimal value of the DC side voltage with a zero total harmonic distortion (THD) of the source current and a unit power factor is obtained for a typical load, through the equivalent circuit analysis and the Fourier Transform analytical expressions. Second, when the DC side voltage of SPQC is lower than the above-obtained minimal value, the quantitative relationship between the DC side voltage and the THD after compensation is also elaborated using the curve diagram. Hardware experimental results verify the design method.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.385-390
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• 2000

This paper deals with the design and simulation of the hybrid power filter to compensate reactive power and harmonic components of nonlinear load. Control target is a 3-phase diode full bridge rectifier with L-R-C nonlinear load, this load is assumed adjustable speed driver(ASD). The hybrid filter consists of a shunt active filter, shunt passive filters and series inductors. Control algorithm is based on instantaneous power compensation theory proposed by H.Akagi and etc. The result from simulation shows the hybrid filter is superior than other filters on the point of compensation performance and low cost. The PSCAD/EMTDC 3.0 is used as simulation tools.

• Journal of Chest Surgery
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• 제23권6호
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• pp.1191-1203
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• 1990

Pulmonary atresia and ventricular septal defect with major aortopulmonary collateral arteries [abbreviated as PA+VSD+MAPCA in the following] has limited the success of attempts at accurate diagnosis and complete surgical repair. From April 1986 to September 1990, 23 patients with PA+VSD+MAPCA among 96 patients of PA+VSD in Seoul National University Children’s Hospital were encountered. The group comprised 14 male and 9 female patients with ages ranging from 17 days to 177 months [mean 49.6 months]. We operated one stage total repair on good pulmonary artery sized two patients by R.E.V. [Reparation a l’etage ventriculaire] and Rastelli operation respectively. And the 11 patients who had independent MAPCAs and hypoplastic central pulmonary artery were dealt with unifocalization and modified Blalock-Taussig Shunt and followed by second stage repair in 3 patients later. We successfully had managed 7 patients whose MAPCAs could be ligated with modified Blalock-Taussig Shunt and followed by second stage repair in 3 patients with R.E.V or Rastelli operation. Recently, three obstruction after 11 unifocalization procedures made us to try palliative right ventricle-pulmonary artery conduit operation by Gore-Tex vascular graft interposition under cardiopulmonary bypass. And so we managed another 3 patients with these procedures for the purpose of pulmonary artery growth whose central pulmonary artery were severely hypoplastic. We experienced one death after second stage repair whose central pulmonary artery was created by 12mm Gore-Tex vascular graft and was unifocalized.

• 한국임상수의학회지
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• 제24권2호
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• pp.269-275
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• 2007

Two dogs referred to Veterinary Medical Center, Chungbuk National University diagnosed as multiple extrahepatic portosystemic shunt were reported. The first dog was a 20-month-old, 8 kg, male Cocker spaniel with history of peritoneal effusion, diarrhea, anorexia and stunted growth. The second dog was a 3-year-old, 13.4 kg, male Jindo with a history of severe depression. Hematologic examination of first dog revealed mild microcytosis and nonregenerative anemia. All of 2 cases, serum chemical values showed increase of serum ammonia, ALP, r-GTP and glucose. In survey radiography, microhepatia was apparent. In the color Doppler ultrasonographic examination, the first dog revealed a dilated tortuous vein communicating with caudal vena cava was observed near the left kidney and the second dog revealed numerous shunting vessels ventral to L5 and L6. Transcolonic portal scintigraphy of the first dog confirmed the presence of portosystemic shunt. In intraoperative jejunoportography, the first dog showed single congenital extrahepatic portosystemic shunt and multiple acquired extrahepatic portosystemic shunts. The second dog showed multiple acquired extrahepatic portosystemic shunts. In these dogs, the presence of congenital and acquried portosystemic shunts and histopathologic findings were considered to represent a combination of multiple extrahepatic portosystemic shunts and noncirrhotic portal hypertension or portal vein hypoplasia.

• 한국전기전자재료학회논문지
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• 제15권9호
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• pp.743-749
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• 2002

A 1.5V 70㏈ 100MHz CMOS class-AB complementary operational amplifier is presented. For obtaining the high gain and the high unity gain frequency, the input stage of the amplifier is designed with rail-to-rail complementary differential pairs which are symmetrically parallel-connected with the NMOS and the PMOS differential input pairs, and the output stage is designed to the rail-to-rail class-AB output stage including the elementary shunt stage technique. With this design technique for output stage, the load dependence of the overall open loop gain is improved and the push-pull class-AB current control can be implemented in a simple way. The designed operational amplifier operates perfectly on the complementary mode with 180$^{\circ}$ phase conversion for 1.5V supply voltage, and shows the push-pull class-AB operation. In addition, the amplifier shows the DC open loop gain of 70.4 ㏈ and the unity gain frequency of 102 MHz for $C_{L=10㎊∥}$ $R_{L=1㏁}$ Parallel loads. When the resistive load $R_{L}$ is varied from 1 ㏁ to 1 ㏀, the DC open loop gain of the amplifier decreases by only 2.2 ㏈.a$, the DC open loop gain of the amplifier decreases by only 2.2 dB.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.150-154
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• 2007

Transponders of RFID system are classified as active or passive depending on the type of power supply they use. In passive transponders the data carrier has to obtain its power from the induced voltage. The induced voltage is converted into direct current using a low loss bridge rectifier and then smoothed. In practice, the induced voltage in the transponder coil is variable according to the coupling coefficient k and the load resistance ($R_L$). Therefore, the rectified voltage is unstable and the transponder of RFID is unstable sometimes. In this paper, a voltage-dependent shunt resistor ($R_s$) circuits are designed and inserted in parallel with the load resistance of RFID transponder in order to improve the stability of power.

• Journal of Chest Surgery
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• 제25권4호
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• pp.391-397
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• 1992

Postoperative hypoxemia in the absence of hypoventilation occurs more often after thoracic or upper abdominal surgery than lower abdominal operations or surgery on extremities. Although the factors which produce postoperative alveolar collapse have not been fully evaluated, the dominant factor of postoperative hypoxia is shunt of blood passing collapsed alveoli and the postoperative pain is associated with restriction of depth of breathing, sighing and movement. In 1979, the first successful clinical usage of epidurally administered morphine was done by Behar and associates for control of postoperative pain. This study was carried out for twenty patients who received posterolateral thoracostomy with Bled resection between May 1990 and May 1991 and who were primary spontaneous recurrent pneumothoraxes. We selected ten of twenty patients, one after the other and treated with epidural analgesia as study group and the remainder ten were grouped as control. Epidural catheters were inserted for study group before operation through T12-L1, 2 interspinous process at the pain clinic or operation room by anesthesiogist and then the drugs[0.25% Bupivacaine 15ml mixing with morphine 3mg] were instillated through the catheter before extubarion and once a day until 4th day, and the patients of control group were treated intermittently by Demerol 50mg intramuscularly for postoperative pain control. The epidural catheters were removed at postoperative 4th day. Observations were done about vital aigns, a-BGA, tidal volume, FVC and occurence of adverse effects during postoperative 2hr, 8hr, 1st day, 2nd day, 7th day in both groups. The results were as follows; [1] Tidal volume[85.1$\pm$29.8%R VS 60.8$\pm$20.5%R, p<0.05] and FVC[53.7$\pm$14.2%R, VS 35.5$\pm$9.l%R, p<0.01] were significantly improved in study group compared with control group during the first day of operation. [2] But the improvement of FVC was delayed after stopping of epidural analgesia[postoperative 7th day, 97.5$\pm$12.3%R VS 83.9$\pm$15.6%R, P <0.05]. [3] Others were statistically not significant. [4] The side effects of epidural analgesia were identified such as urinary retention[2 cases], itching sensation[1 case] and headache[1 case], but there was no need for active treatments.