• The Transactions of the Korean Institute of Power Electronics
• /
• v.10 no.4
• /
• pp.403-410
• /
• 2005

This Paper Presents development of solar may shunt switching unit with a fully regulated Power regulation for Geostationary Earth Orbit(GEO) satellite. This shunt switching unit comprises the solar may shunt modules that regulate the solar array power. These solar array shunt modules connect/disconnect the solar array segments to/from the bus through switching actions. And that is also possible simply extension to an existing design by FPGA control logic changing. In order to verify the proposed design, the control logic and worst case analysis are analyzed and the simulation and experimental results we shown.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.834-836
• /
• 2003

This paper describes the optimal design, construction and performance evaluation of coaxial shunts used in high current testing laboratory for current measuring system. These shunts, which are of tubular type coaxial shunts, the currents to be measured range from Amperes to several kiloAmperes, and the frequency of the signals has a bandwidth from DC to megaHertz. The shunt must have the mechanical strength to support the forces produced by the transient current, above all, the measuring capabilities of shunt are dependent upon short response time and it must be as free as possible of inductive effects. In this paper presents both characteristic of shunt and design of tubular type coaxial shunt.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.1
• /
• pp.42-47
• /
• 2010

The power burden of high-$T_c$ superconducting (HTSC) elements comprising superconducting fault current limiter (SFCL) using magnetic coupling of shunt reactors was analyzed. The magnetically coupled shunt reactors play a role in distributing the even power burden between HTSC elements comprising the SFCL, which contributes to the effective current limiting and recovery characteristics of the SFCL. It was confirmed through the comparative analysis on the SFCLs with both the magnetically coupled and the magnetically uncoupled shunt reactors that the magnetically coupled shunt reactors could improve the SFCL's performance by equalizing the power burden of HTSC elements.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.1
• /
• pp.7-12
• /
• 2006

In this paper, vibration suppression of a CD-ROM main base with piezoelectric shunt circuit is studied. Admittance is introduced to predict the performance of piezoelectric shunt damping. Numerical admittance obtained by commercial finite element code, ANSYS, correlates well with experimentally measured one. Multi-mode piezoelectric shunt damping is realized based on the target mode and frequencies obtained by the admittance analysis. Experimental results prove that admittance of the piezoelectric structure is capable of predicting the performance of piezoelectric shunt damping and the vibration of the main base with the piezoelectric patches is reduced effectively.

• Clinical Endoscopy
• /
• v.55 no.1
• /
• pp.146-149
• /
• 2022

Lumboperitoneal or ventriculoperitoneal shunt insertion is a standard therapy for hydrocephalus that diverts cerebrospinal fluid from the subarachnoid space into the peritoneal cavity. Gastrointestinal perforations due to this procedure occur rarely; however, accepted treatment strategies have not yet been established. Hence, the most common treatment approaches are open surgery or spontaneous closure without endoscopy. We report the case of a small intestinal perforation in a 73-year-old-woman that occurred after the insertion of a lumboperitoneal shunt. A positive cerebrospinal fluid culture and high cerebrospinal fluid white blood cell count indicated a retrograde bacterial infection, and computed tomography revealed that the peritoneal tip of the shunt catheter was located in the lumen of the gastrointestinal tract. We repaired the perforation endoscopically using an over-the-scope clip, and the patient's recovery was uneventful. Use of an over-the-scope clip could be an effective and minimally invasive treatment for intestinal perforations caused by lumboperitoneal or ventriculoperitoneal shunt insertion.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.12
• /
• pp.1375-1380
• /
• 2001

Objective : The authors analyzed the incidence, the cause and the prognosis of hydrocephalus following aneurysmal subarachnoid hemorrhage to evaluate the risk factors of hydrocephalus and to provide the proper treatment method for hydrocephalus following aneurysmal subarachnoid hemorrhage. Methods : The 505 cases of subarachnoid hemorrhage followed by aneurysmal surgery from January 1990 to May 1999, were divided into shunt group and shunt-free group and we were reviewed for the clinical status, Fisher's grade, brain CT findings and prognosis. Results : The incidence of acute hydrocephalus was 37.2% of patients and 18.9% to developed chronic hydrocephalus. Shunt surgery due to chronic hydrocephalus was required in 6.5% of patients. We found following variables were significantly related to shunt-dependent hydrocephalus : high Hunt-Hess and Fisher grade, initial CT findings of intraventricular hemorrahge, posterior circulation aneurysm, preoperative rebleeding, delayed ischemic deficits, and initial high ventricular size index. There were no statistically significant relationships between shunt-dependent hydrocephalus and patient age or sex, timing of operation. The previous hypertension was not related to shunt dependent hydrocephalus. Prognosis in shunt group showed poor result. Conclusion : The risk factors of hydrocephalus following aneurysmal subarachnoid hemorrhage are high Hunt-Hess grade, high Fisher's grade, aneurysms of posterior circulations, preoperative aneurysmal rebleeding, delayed ischemic deficits, initial CT findings of intraventricular hemorrahge and initially increased ventricular size. The patients with these factors should the carefully observed and managed accordingly due to poor prognosis related to hydrocephalus requiring shunt operation.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.10
• /
• pp.123-130
• /
• 2007

Hypoplastic left heart syndrome is currently the most lethal cardiac malformation of the newborn infant. Survival following a Norwood operation depends on the balance between systemic and pulmonary blood flow, which is highly dependent on the fluid dynamics through the interposition shunt between the two circulations. The purpose of this study is an optimization of the systemic-to-pulmonary artery shunt. In this study, We used computational fluid dynamic(CFD) models to determine the velocity profile in a systemic-to-pulmonary artery shunt and suggested a simplified method of calculating the blood flow in the shunt based on Ultrasound systems. We analyzed the flow characteristic variations and oscillatory shear index(OSI) due to the anastomosis angle and shunt diameter changing. Four different CFD models were constructed with the shunt sizes ranging from 3 to 3.5mm. The angle between the brachiocephalic trunk(BCT) and the shunt were $30^{\circ}$ and $45^{\circ}$, respectively. When the diameter is 3.0 mm, the oscillatory shear index decreased by 1.2% at $30^{\circ}$ as opposed to at $45^{\circ}$. When the diameter is 3.5 mm, it increased by 18% more at $30^{\circ}$ as opposed to at $45^{\circ}$. When the joint angle is $30^{\circ}$ and the diameter is 3.0 mm, the oscillatory shear index decreased by 4.1% in comparison with the 3.5 mm diameter. When the angle is $45^{\circ}$ and the diameter is 3.0 mm, the index increased by 14.6% in comparison with the 3.5 mm diameter.

• Advances in pediatric surgery
• /
• v.6 no.2
• /
• pp.89-94
• /
• 2000

Ventriculoperitoneal shunt(VP shunt) for hydrocephalus is thought to inhibit the closure of processus vaginalis and promote inguinal hernia by increasing intraabdominal pressure. To estimate the patency rate of processus vaginalis and the incidence and characteristics of the inguinal hernia, 262 cases of VP shunt in early childhood between January 1980 and May 1998 at Seoul National University Children Hospital were reviewed retrospectively. Inguinal hernia developed in 28 cases(10.7 %), but six patients had an inguinal hernia before the VP shunt was placed. Patients who had a VP shunt before 6 months of age developed inguinal hernia in 16.2 %(12/74) of cases, patients shunted between 6 months and 2 years had an incidence of 12.4 %(11/89) and only 5.1 %(5/99) of patients operated upon after 2 years of age developed hernias. Twenty-two patients out of 256 cases (8.6 %) developed inguinal hernia after VP shunt, with male predominance(M : F=4.5:1). Eight patients developed inguinal hernia bilaterally(36.4 %). It is suggested that at least 14% of processus vaginalis is patent until 2 years old.

• Journal of Korean Neurosurgical Society
• /
• v.48 no.6
• /
• pp.480-484
• /
• 2010

Objective : To evaluate the role of lumbar drainage in the prevention of shunt-dependent hydrocephalus after treatment of ruptured intracranial aneurysms by coil embolization in good-grade patients. Methods : One-hundred-thirty consecutive patients with aneurysmal subarachnoid hemorrhage in good-grade patients (Hunt & Hess grades I-III), who were treated by coil embolization between August 2004 and April 2010 were retrospectively evaluated. Poor-grade patients (Hunt & Hess grades IV and V), a history of head trauma preceding the development of headache, negative angiograms, primary subarachnoid hemorrhage (SAH), and loss to follow-up were excluded from the study. We assessed the effects on lumbar drainage on the risk of shunt-dependent hydrocephalus related to coil embolization in patients with ruptured intracranial aneurysms. Results : One-hundred-twenty-six patients (96.9%) did not develop shunt-dependent hydrocephalus. The 2 patients (1.5%) who developed acute hydrocephalus treated with temporary external ventricular drainage did not require permanent shunt diversion. Overall, 4 patients (3.1%) required permanent shunt diversion; acute hydrocephalus developed in 2 patients (50%). There was no morbidity or mortality amongst the patients who underwent a permanent shunt procedure. Conclusion : Coil embolization of ruptured intracranial aneurysms may be associated with a lower risk for developing shunt-dependent hydrocephalus, possibly by active management of lumbar drainage, which may reflect less damage for cisternal anatomy than surgical clipping. Coil embolization might have an effect the long-term outcome and decision-making for ruptured intracranial aneurysms.

• Journal of Korean Neurosurgical Society
• /
• v.52 no.1
• /
• pp.58-61
• /
• 2012

Various surgical procedures for the treatment of post-traumatic syringomyelia have been introduced recently, but most surgical strategies have been unreliable. We introduce the concept and technique of a new shunting procedure, syringo-subarachnoid-peritoneal shunt. A 54-year-old patient presented to our hospital with a progressive impairment of motion and position sense on the right side. Sixteen years before this admission, he had been treated by decompressive laminectomy for a burst fracture of L1. On his recent admission, magnetic resonance (MR) imaging studies of the whole spine revealed the presence of a huge syrinx extending from the medulla to the L1 vertebral level. We performed a syringo-subarachnoid-peritoneal shunt, including insertion of a T-tube into the syrinx, subarachnoid space and peritoneal cavity. Clinical manifestations and radiological findings improved after the operation. The syringo-subarachnoid-peritoneal shunt has several advantages. First, fluid can communicate freely between the syrinx, the subarachnoid space, and the peritoneal cavity. Secondly, we can prevent shunt catheter from migrating because dural anchoring of the T-tube is easy. Finally, we can perform shunt revision easily, because only one arm of the T-tube is inserted into the intraspinal syringx cavity. We think that this procedure is the most beneficial method among the various shunting procedures.