• Clinical and Experimental Pediatrics
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• v.52 no.10
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• pp.1175-1180
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• 2009

We report a case of a full-term neonate with persistent pulmonary hypertension who developed asphyxia after birth and was treated with iloprost. The neonate had persistent hypoxia and did not respond to supportive treatment. Because inhaled nitric oxide (iNO) was not available in our hospital, inhaled iloprost was administered via an endotracheal tube. This resulted in an immediate elevation of oxygen saturation. Echocardiography revealed the conversion of the right-to-left ductal shunt to the left-to-right one and a decrease of the right ventricular pressure. The use of inhaled iloprost did not cause any significant side effects. Here, we describe our experience where iloprost was used in a neonate with persistent pulmonary hypertension because the standard therapy with inhaled nitric oxide was not available.

• Journal of Korean Neurosurgical Society
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• v.39 no.5
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• pp.335-339
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• 2006

Objective : The authors present eight cases of immediate post-operative epidural hematomas[EDHs] adjacent to the craniotomy site, describe clinical details of them, and discuss their pathogenesis. Methods : Medical records of eight cases were retrospectively reviewed and their clinical data, operation records, and radiological findings analyzed. Any risk factors of the EDHs were searched. Results : In 5 of 8 cases, adjacent EDHs developed after craniotomies for the surgical removal of brain tumors. Three cases of adjacent EDHs developed after a pterional approach and neck clipping of a ruptured anterior communicating artery aneurysm, a ventriculoperitoneal shunt, and a craniotomy for a post-traumatic EDH, respectively. In all eight cases, brain computed tomography[CT] scans checked immediately or a few hours after the surgery, revealed large EDHs adjacent to the previous craniotomy site, but there was no EDH beneath the previous craniotomy flap. After emergent surgical removal of the EDHs, 7 cases demonstrated good clinical outcomes, with one case yielding a poor result. Conclusion : Rapid drainage of a large volume of cerebrospinal fluid or intra-operative severe brain collapse may separate the dura from the calvarium and cause postoperative EDH adjacent to the previous craniotomy site. A high-pressure suction drain left in the epidural space may contribute to the pathogenesis. After the craniotomy for brain tumors or intracranial aneurysms, when remarkable brain collapse occurs, an immediate postoperative brain CT is mandatory to detect and adequately manage such unexpected events as adjacent EDHs.

• Journal of Korean Neurosurgical Society
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• v.29 no.9
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• pp.1209-1214
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• 2000

Objectives : The measurement of resistance to cerebrospinal fluid outflow($R_o$) can clearly delineate cerebrospinal fluid dynamics in patients with ventricular dilatation and can help in selecting patients to undergo shunt placement. With regards to type of infusion method, bolus injection is known to be more practical and safer than continuous infusion. The purpose of this study was to obtain $R_o$ of normal adults using lumbar bolus injection method. Material and Methods : Twenty adults aged 25 to 52 years were studied using lumbar bolus injection method. Fifteen patients with hemifacial spasm and five with cerebral concussion underwent $R_o$ measurement under propofol general anesthesia and local anesthesia, respectively. Results : The mean values of $R_o$ determined 1 minute and 2 minutes after bolus injection were $4.8{\pm}1.7$ and $4.4{\pm}1.6mmHg/ml/min$, respectively. There was no significant difference of $R_o$ between propofol general anesthesia group and local anesthesia group. Two patients showed $R_o$ greater than 6mmHg/ml/min. One patient revealed unexpectedly high level of $R_o$ due to severe spinal stenosis. Conclusion : Mean Ro in this study was higher than that of Shapiro's study. Borderline Ro near 6mmHg/ml/min should be regarded with caution and compared with clinical symptoms and results of other studies. Patients with severe spinal stenosis should be evaluated with caution.

• Journal of Korean Neurosurgical Society
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• v.29 no.9
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• pp.1195-1203
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• 2000

Objective : To confirm the efficacy of functional hemispherectomy and peri-insular hemispherotomy on treatment of intractable epilepsy. Materials & Methods : From April 1997 to February 1999, we performed 1 functional hemispherectomy and 6 peri-insular hemispherotomy in 7 consecutive patients. These procedures result in completely disconnected hemisphere while maintaining the disconnected portion of the hemisphere intact within the surgical cavity. The indications were hemimegalencephaly in 2 cases, infarction with encephalomalacia in 2, Sturge-Weber syndrome in 1, hemiconvulsion hemiplegia epilepsy syndrome in 1, cortical dysplasia with leptomeningeal cyst in 1. Mean follow-up is 15.8 months(range 8-28 months). Results : Among 7 patients, 1 patient died immediately after peri-insular hemispherotomy. Five patients became seizure free with reduced doses of medications. One patient developed rare disabling seizure with medication. In 6 patients, there were improvements in the function of the hemiparetic limbs in the postoperative phase. A 3-year-old boy with infarction and encephalomalacia died few hours after surgery due to postoperative hypothermia. Two patients required shunt after surgery. Two patients developed postoperative brain swelling but were successfully managed with conservative care. Conclusion : In conclusion, functional hemispherectomy and peri-insular hemispherotomy may provide substantial seizure control in selected cases of young hemiplegic patients with intractable epilepsy.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.447-450
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• 1997

A new technique for the preparation of porous vascular prostheses was investigated. Polyurethane solution (10 to 14wt%) was injected into a mold. After freezing at low temperature $(0^{\circ}C\sim-40^{\circ}C)$, solvent was dissolved out with water at $0^{\circ}C$ to form porous tubes. The average pore size $(<10{\mu}m)$and pore occupation (10% to 51%) were easily changed by changing polyurethane concentration, freezing temperature, and freezing methods. This technique can give a proper pore size $(30\sim60{\mu}m)$ for tissue ingrowth, and suitable compliances for matching with arteries and veins. This method might give a desired compliant graft for artificial implantation with the presently valid medical polymers.

• Journal of Chest Surgery
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• v.23 no.6
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• pp.1118-1127
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• 1990

Arterial switch operation for repair of nineteen cases of transposition of the great arteries associated with ventricular septal defect and three cases with double outlet right ventricle with subpulmonary ventricular septal defect[Taussig-Bing type DORV] was performed from November 1987 to September 1990 at the Seoul National University Children`s Hospital. Sixteen of them were under six months of age, and three were under one year of age with body weight ranged from three to fourteen kilograms. Preoperative cardiac catheterization was done in eighteen patients, in which the pressure of the left ventricle was greater than 70% of the right ventricle in all but one. Patent ductus was associated in thirteen cases[68.4%] of TGA+VSD, and atrial septal defect or patent oval foramen was in sixteen cases. Four atrial septostomy, one modified Blalock- Taussig shunt, one pulmonary artery banding, one coarctoplasty using subclavian arterial flap, were perfomed before arterial switch operation. There were five hospital deaths, all in the. patients with transposition of the great arteries with ventricular septal defect[overall mortality rate 22.7%]. Lecompte Maneuver was used in all patients, and in all patient the U-shaped flap of coronary arteries were transposed to V-shaped cleavage created in the neoaorta. Arterial defect in the neopulmonary artery was covered with 0.0625% Glutaraldehyde fixed autogenous pericardium There have been no late deaths, Postoperative cardiac catheterization and angiocardiogram in four patients has revealed no stenosis in the neopulmonary artery or neoaorta with reasonable P[RV/LV], Anatomic correction for transposition and double outlet right ventricle with subpulmonary ventricular septal defect would seem to be a good operative alternative to intraatrial switch procedures, with the advantage of incorporating the left ventricle to systemic circulation.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.317-321
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• 2011

Objective : External ventricular drain (EVD) is commonly performed with a freehand technique using surface anatomical landmarks at two different cranial sites, Kocher's point and the forehead. The aim of this study was to evaluate and compare the accuracy and safety of these percutaneous ventriculostomies. Methods : A retrospectively review of medical records and head computed tomography scans were examined in 227 patients who underwent 250 freehand pass ventriculostomy catheter placements using two different methods at two institutions, between 2003 and 2009. Eighty-one patients underwent 101 ventriculostomies using Kocher's point (group 1), whereas 146 patients underwent 149 forehead ventriculostomies (group 2). Results : In group 1, the catheter tip was optimally placed in either the ipsilateral frontal horn or the third ventricle, through the foramen of Monro (grade 1) in 82 (81.1%) procedures, in the contralateral lateral ventricle (grade 2) in 4 (3.9%), and into eloquent structures or non-target cerebrospinal space (grade 3) in 15 (14.8%). Intracerebral hemorrhage (ICH) >1 mL developed in 5 (5.0%) procedures. Significantly higher incidences of optimal catheter placements were observed in group 2. ICH>1 mL developed in 11 (7.4 %) procedures in group 2, showing no significant difference between groups. In addition, the mean interval from the EVD to ventriculoperitoneal shunt was shorter in group 2 than in group 1, and the incidence of EVD-related infection was decreased in group 2. Conclusion : Accurate and safe ventriculostomies were achieved using both cranial sites, Kocher's point and the forehead. However, the forehead ventriculostomies provided more accurate ventricular punctures.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.3
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• pp.1-14
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• 1974

The gain stability of the nuclear pulse linear amplifiers with feedback for such a fast pulse input as the step voltage or the nuclear radiation detector pulse is analysed in detail. The expression is derived which describes the waveform at the anode circuit of the photomultiplier tube which is a part of the nuclear radiation detector. It is analysed and compared when the feedback amplifier has one and two time-constants. When these fast input pulse voltages are applied to the feedback amplifier, the effects of feedback in linearity and stability of the output voltage appear only after two or three rise-times of the amplifier, And it is proved that in order to reduce this limitation, the rise time of the feedback amplifier shou1d be less than the input pulse width. It is also shown that the above theory can be applied directly to the voltage-shunt feedback amplifier stages designed as the basic amplifier of the linear amplifier, and that the gain stability is more improved for the smaller input impedance of this amplifier stage.

• Tuberculosis and Respiratory Diseases
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• v.67 no.1
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• pp.52-58
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• 2009

Pulmonary arteriovenous malformation (PAVM) is a rare pulmonary vascular anomaly due to an abnormal communication between the pulmonary artery and vein. The most common presenting symptom is a dyspnea on exertion related to this right-to-left shunt. If left untreated, PAVM has been known to result in serious complications. Incomplete pulmonary capillary network can be the cause of cerebral abscesses and other noninfectious neurological complications, such as stroke and transient ischemic attacks due to paradoxic embolism Transcatheter embolotherapy, using coils or balloons, has replaced surgical resection as the treatment of choice for PAVM. However, the risk of device embolization has limited the use of coil embolotherapy, while the size of PAVM is huge. Recently, Amplatzer$^{(R)}$ Vascular Plug has been proposed as an alternative endovascular occlusion device for arteriovenous malformation. We report a case of 81-year-old male patient with a giant PAVM, which was successfully treated by transcatheter embolotherapy using the Amplatzer$^{(R)}$ Vascular Plug.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.274-284
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• 2003

Multi-level converter that is high-capacity electric power conversion system is used widely to electric motor drive system and FATCs(Flexible AC Transmission Systems). H-Bridge converter has been prevalently applied to shunt-type system because it can be easily expanded to the multi-level. In steady states, converter is normally operated in the range of 0.7∼0.8 of modulation Index. Even though zero vectors are not imposed to high modulation index, DC-Link voltage Is constant. It means that converter has another boost vector except for zero vectors among several vectors in 3-level converter. This paper has examined the principle of boost vector and investigated the difference between another boost vector and zero vectors in 3-level converter. In addition, this paper has analysed and compared the charging currents and the capacitor voltages of two topologies. The currents and voltages are related to reference voltage. Therefore, it proposed the calculation method for the voltage ripple and the charging current of each capacitor and compared various DC-Link voltage control methods through the simulation.