• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1158-1168
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• 2005

A shunt from the left ventricle to the left anterior descending artery is being developed for coronary artery occlusive disease, in which the shunt or conduit connects the the left ventricle (LV) with the diseased artery directly at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Computational fluid dynamic analysis for the shunt hemodynamics was also done using a commercial finite element package. Simulation results indicate that in complete left anterior descending artery (LAD) occlusion, flow can be returned to approximately 65% of normal, if the conduit resistance is equal for forward and reverse flow. The net coronary flow can increase to 80% when the backflow resistance is infinite. The increases in flow rate produced by asymmetric flow resistance are enhanced considerably for a partial LAD obstruction, since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but considerably augments it when the resistance is asymmetric. The computational results suggest that an LV-LAD conduit will be beneficial when the resistance due to artery stenosis exceeds 27 PRU, if the resistance is symmetric. Fluid dynamic simulations for the shunt flow show that a recirculating region generated near the junction of the coronary artery with the bypass shunt. The secondary flow is induced at the cutting plane perpendicular to the axis direction and it is in the attenuated of coronary artery.

• Journal of Chest Surgery
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• 제5권2호
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• pp.107-112
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• 1972

Recently we experienced a case of the portal hypertension, extrahepatlc origin in the National Medical Center, Seoul. The case was a male aged 19 who was undergone the elective splenorenal shunt with splenectomy 9 years ago and emergency ligation of the coronary vein because of recurred variceal rupture 6 years later and had recurring esophageal varices with bleeding this time.At the age of 10 he had been occasionally suffering from nasal bleeding and visited to our Pediatric department, when there was encountered for the first time the splenomegaly, esophageal varices in the lower third esophagus on the esophagogram, and stenosis and kinking of the portal vein with rich collateral circulation on the splenoportography without hepatic functional impairment.The elective splenorenal shunt with splenectomy was undergone under the diagnosis of portal hypertension due to congenital anomaly of the portal vein and postoperatlvely no troubles had been obtained until postoperative 1st attack of massive hematemesis due to esophagenl variceal rupture recurred about 6 years later which was confirmed by control esophagogram and it was resulted by stenosis of previous anastomotic site of the splenorenal shunt.Then emergency ligation of the coronary vein was only made for bleeding control and no episodes of hematemesis had been encountered thereafter until April 1972 about 3 years after the 2nd operation, when hematemesis recurred again. In this time, recurring esophageal varices were noted in the lower third esophagus on the control esophagogram and he was employed side to end mesocaval shunt as the final step of portal decompression,and following results were obtained. 1] No postoperatlve troubles as leg edema or pain: Postoperatively leg elevation and elastic bandage on the both legs were employed until discharge. 2] During operation the portal pressure was 300 mm $H_2O$ and immediately lowered to 170 mm $H_2O$ after shunt.

• Journal of Korean Neurosurgical Society
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• 제30권sup2호
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• pp.364-367
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• 2001

A 4-month-old female patient admitted because of hydrocephalus. She was premature infant with germinal matrix hemorrhage at gestational period 27 wks. A ventriculoperitoneal shunt with a low-pressure type valve was placed. Follow-up CT scan obtained 3 months after VP shunt placement, revealed a new Lt. middle cranial fossa cyst. The girl was readmitted to hospital at 7 months after VP shunt placement, complaining of lethargy and vomiting. A CT scan was demonstrated a increase in size of a cyst, She subsequently underwent a left-sided pterional craniotomy with partial excision of membrane and cyst fenestration into the basal cisterns. Follow-up CT scan after 18 months revealed reaccumulation of cyst, the girl was reoperated on. After 2 months, the size of cyst was not decreased. Finally, She underwent a cystoperitoneal shunt. Follow-up CT scan after 5 months was demonstrated disappeared cyst and reexpansion of brain parenchyma. We report the development of a symptomatic sylvian fissure arachnoid cyst developed after ventriculoperitoneal shunt.

• Journal of Chest Surgery
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• 제21권1호
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• pp.152-157
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• 1988

Traumatic aorta-right ventricular shunt is an uncommon but important phenomenon due to development of irreversible cardiac dysfunction. Aorto-right ventricular shunt and aortic valvular laceration following stab wound of the chest was successfully surgically repaired in a twenty-year-old male patient. With the brief review of literatures, we describe the case.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.596-597
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• 2017

For General Purpose Inverter dedicated in Motor drive, this market is blood market due to low market price. So, developing engineer must consider the cost reduction plan and do action. This inverter always needs to measure current and shunt solution can be one of cost reduction solution.

• Journal of Korean Neurosurgical Society
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• 제30권sup1호
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• pp.99-107
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• 2001

Objective : Hydrocephalus and vasospasm are the common complications following subarachnoid hemorrhage (SAH). In spite of development of perioperative management and operative technique, hydrocephalus cause neurological deficit and poor prognosis. Usually CSF drainage procedure(external ventricular drainage(EVD) or shunt) is needed in hydrocephalus following SAH. The aim of this study was to investigate whether the need for shunting and the outcome after shunting in hydrocephaus following SAH can be related to the duration, daily and total amount of cerebrospinal fluid(CSF) drainage at EVD. Material and Method : IVH is one of several factors which cause hydrocephalus. In this retrospective study, firstly we investigated the incidence of IVH in total cases and frequency of IVH according to aneurysmal site and then prognosis of IVH following SAH. Among 629 patients with SAH, hydrocephalus was diagnosed by CT scan and symptoms. And then those 102 hydrocephalus following SAH were divided into two groups which were hydrocephalus with IVH group and without IVH group. In these two groups, we investigated and compared the incidence of hydrocephalus in all case, frequency of hydrocephalus according to aneurysmal site, the outcome according to H-H grade on admission and the need rate of shunt, etc. Of those hydrocephalus, 100 EVD procedures were done. The duration, daily and total amount of CSF drainage at EVD were investigated. Fifty cases expired during EVD was excluded. We analyzed whether the need rate of shunt and the final outcome after shunting can be related to IVH, the duration and daily and total amount of CSF drainage. Result : The incidence of hydrocephalus following SAH was 20%(with IVH group ; 64%, without IVH group ; 11%). As H-H grade on admission was better, the outcome of hydrocephalus was also better. The mortality rate of hydrocephalus with IVH was 64% which was higher than 40% that of hydrocephalus without IVH. The need rate of shunt in all cases of hydrocephalus following SAH was 20%, but those with IVH group excluding expired patients before shunt was 40%. This was very similar to 41% of the need rate of shunt in hydrocephalus without IVH. The total amount of CSF drainage was statistically related to the need rate of shunt(total amount : need rate of shunt/<1000cc : 15%, 1000-2000cc : 40%, >2000cc : 50%). The duration and daily amount of CSF drainage were not statistically related to the need rate of shunt, but as daily amount of CSF drainage was more and duration was longer, the need rate of shunt was increased(daily amount : need rate of shunt /<100cc : 16%, 100-200cc : 25%, >200cc : 40%//duration : need rate of shunt/<1week : 8%, 1-2weeks : 30%, >2weeks : 47%), and also the final outcome after shunting was poor. Especially the total amount of CSF drainage was significant related to the final outcome after shunting(total amount : GOS/<1000cc : I&II(3/4), 1000-2000cc : II(2/4), III(2/4), >2000cc : III&IV(6/7)). Conclusion : This study revealed that the incidence and mortality rate of hydrocephalus following SAH were influenced by IVH. So SAH associated IVH has the higher incidence of hydrocephalus and poor outcome. As the CSF drainage amount was more and duration of drainage was longer, the need rate of shunt was increased and the final outcome after shunting was poor. Especially the total amount of CSF drainage were strongly related to the need rate of shunt and the outcome after shunting.

• Journal of Korean Neurosurgical Society
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• 제57권4호
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• pp.311-313
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• 2015

Chiari type I malformation is a tonsillar herniation more than 3 mm from the level of foramen magnum, with or without concurrent syringomyelia. Different surgical treatments have been developed for syringomyelia secondary to Chiari's malformations: craniovertebral decompression with or without plugging of the obex, syringo-subarachnoid, syringo-peritoneal, and theco-peritoneal shunt placement. Shunt placement procedures are useful for neurologically symptomatic large-sized syrinx. In this paper, authors define the first successful treatment of a patient with syringomyelia due to Chiari type I malformation using a pre-defined new technique of syringo-subarachnoid-peritoneal shunt with T-tube system.

• Journal of Chest Surgery
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• 제28권11호
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• pp.983-988
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• 1995

From January 1983 to December 1994, 48 cyanotic patients were underwent a subclavian artery-pulmonary artery shunt using polytetrafluoroethylene[PTFE for the purpose of improvement of reduced pulmonary blood flow. The diameters of the PTFE used were 4mm[4 cases , 5mm[36 cases , and 6mm[8 cases sizes. The effectiveness of modified Blalock-Taussig shunts was evaluated clinically and angiographically. There were 5 early deaths and 2 late deaths. There were 3 early shunt failures and 5 late shunt failures. The overall graft patency rate was 83.3%. Postoperative hemoglobin was reduced significantly[p = 0.0011 in comparison of the preoperative and postoperative hemoglobin, SaO2, PaO2, and cardiothoracic ratio.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.672-680
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• 2012

This paper proposes the control strategy of the shunt Flexible AC Transmission System (FACTS) devices to improve transient stability in multimachine power system. The multimachine power system has high nonlinear response after severe disturbance. The concept of Lyapunov energy function is applied to derive nonlinear control strategy and it was found that the time derivative of line voltage is not only can apply to control the shunt FACTS devices in multimachine system but also is locally measurable signal. The fuzzy logic control is also applied to overcome the uncertainty of various disturbances in multimachine power system. This paper presents the method of investigating the effect of the shunt FACTS devices on transient stability improvement. The proposed control strategy and the method of simulation are tested on the new England power system. It was found that the shunt FACTS devices based on the proposed nonlinear control strategy can improve transient stability of multimachine power system.

• Journal of Korean Neurosurgical Society
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• 제29권7호
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• pp.886-890
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• 2000

Objective : placement of ventricular catheter is important to achieve long-term patency of the shunt system. We describe a method of calculating the insertion site, trajectory, and the length of the ventricular catheter using CT parameters in shunt surgery. Patients and Methods : These can be rapidly obtained using a caliper from a scout cut and two axial scans at lateral ventricular and upper 3rd ventricular level. To compare this technique with traditional one, we analyzed 40 consecutive patients who underwent shunt surgery. Results : Of 20 patients undergoing ventriculoperitoneal shunt insertion using this technique, none had poor location of the proximal catheter. In the counterpart, 9 patients had poor location(p＝0.001). The number of patients who required revision surgery were also lower in the group using this technique, but it was not statistically significant (4 versus 2, p＝0.422). Mean follow-up period was shorter in this technique group. Conclusion : This technique provides an accurate placement of the proximal catheter without special instrument or additional expenses.