• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.5
• /
• pp.250-256
• /
• 2006

Both ratio error and phase angle error in current transformer(CT) depend critically on values of CT burden. Thus, precise measurement of CT burden is very important for the evaluation of CT. A method for the measurement of CT burden has been developed by employing the portable shunt precise resistor with negligible AC-DC resistance difference less than $10^{-5}$. The burden value(value and power factor) can be calculated from resistance and reactance obtained by measuring the change of ratio error and phase angle error caused by the change of shunt resistor. The uncertainty for the method is evaluated and found to be abut 2 %.

• Journal of Advanced Navigation Technology
• /
• v.16 no.5
• /
• pp.781-786
• /
• 2012

In this paper, we propose the design and performance of an unequal divider using transmission line with periodic capacitor shunt connection. To design divider with a high dividing ratio, we limit a high impedance line value to fabricate microstrip line and also, design a low impedance line of below $10{\Omega}$ using periodic capacitor shunt connection. As a design example, a 10:1 ratio divider was designed and measured at center frequency 1 GHz to show the validity of the unequal divider using periodic capacitor shunt connection. Its performance is in good agreements with the simulated results.

• Journal of Chest Surgery
• /
• v.57 no.3
• /
• pp.231-239
• /
• 2024

Background: Although the modified Blalock-Taussig shunt remains the mainstay method of palliation for augmenting pulmonary blood flow in various congenital heart diseases, the shunt must be carefully designed to achieve the best outcomes. This study investigated the effect of shunt configuration on pulmonary artery growth and growth discrepancy. Methods: Twenty patients with successful modified Blalock-Taussig shunt takedown were analyzed. Pulmonary artery and shunt characteristics were obtained using computed tomography scans. Differences in the baseline and follow-up diameter ratios and growth in the ipsilateral and contralateral arteries were calculated. The angle between the shunt and pulmonary artery, as well as the distance from the main pulmonary artery bifurcation, were measured. Correlations between pulmonary arteries and shunt configurations were analyzed. Results: The median interval time between shunt placement and takedown was 154.5 days (interquartile range, 113.25-276.25 days). Follow-up values of the ipsilateral-to-contralateral pulmonary artery diameter ratio showed no significant correlation with the shunt angle (ρ=0.429, p=0.126) or distance (ρ=0.110, p=0.645). The shunt angle and distance from the main pulmonary bifurcation showed no significant correlation (ρ=-0.373, p=0.189). Pulmonary artery growth was negatively correlated with shunt angle (ipsilateral, ρ=-0.565 and p=0.035; contralateral, ρ=-0.578 and p=0.030), but not with distance (ipsilateral, ρ=-0.065 and p=0.786; contralateral, ρ=-0.130 and p=0.586). Conclusion: Shunt configuration had no significant effect on growth imbalance. The angle and distance of the shunt showed no significant correlation with each other. A more vertical shunt was associated with significant pulmonary artery growth. We suggest a more vertical graft design for improved pulmonary artery growth.

• Journal of Mechanical Science and Technology
• /
• v.17 no.11
• /
• pp.1650-1658
• /
• 2003

This paper deals with a novel shunt circuit, which is capable of suppressing multimode vibration amplitudes by using a pair of piezoceramic patches. In order to describe the characteristic behaviors of a piezoelectric damper connected with a series and a parallel resistor-negative capacitor branch circuit, the stiffness ratio and loss factor with respect to the non-dimensional frequency are considered. The mechanism of the shunt damper is also described by considering a shunt voltage constrained by shunt impedance. To obtain a guideline model of the piezo/beam system with a negative capacitive shunting, the governing equations of motion are derived through the Hamilton's principle and a piezo sensor equation as well as a shunt-damping matrix is developed. The theoretical analysis shows that the piezo/beam system combined with a series and a parallel resistor-negative capacitor branch circuit developed in this study can significantly reduce the multiple-mode vibration amplitudes over the whole structural frequency range.

• Journal of Chest Surgery
• /
• v.22 no.4
• /
• pp.594-600
• /
• 1989

Primary intracardiac repair of tetralogy of Fallot with low mortality and early good results, has been accomplished in recent years. But palliative procedures have been reserved for those hypoplastic pulmonary arteries, a hypoplastic left ventricle or anomalies of the coronary artery would make total correction difficult. And the Blalock-Taussig shunt operation is recognized as a standard and popular palliative procedure. I undertook a retrospective determination of the effect of the Blalock-Taussig shunt operation on the development of the main pulmonary artery and the right and left pulmonary arteries. Between January, 1980, and April, 1987, at the Severance Hospital, 16 patients were studied by cardiac catheterization and angiocardiography, before undergoing Blalock-Taussig shunting procedures for the palliation of severe symptoms of tetralogy of Fallot, and some time later, usually prior to a second procedure. The mean interval between catheterizations was 22.25 months. Patients with tetralogy of Fallot and pulmonary atresia or with an occluded shunt were not included. The primary and secondary angiograms of each patient were reviewed, and measurements of the diameter of the main pulmonary artery, the right and left pulmonary arteries, and the descending thoracic aorta were taken. The results are as follows; 1. The hematocrit decreased from 56.39% to 50.34%[p< 0.05], and the arterial oxygen saturation increased from 62.00 % to 81.31 %[p< 0.001] following shunt procedures 2. The ratio of the diameter of the right pulmonary artery plus the left pulmonary artery to the diameter of the descending thoracic aorta increased 1.30 k 0.28 times [p< 0.01]; but the ratio of the diameter of the main pulmonary artery to the diameter of the descending thoracic aorta increased 1.10 * 0.33 times, which was not. significant[p< 0.05]. 3. The interval between shunting and second catheterization was not related to the magnitude of change in the pulmonary arteries[r=0.141, p >0.05]. 4. The changes in the ratio of the diameter of the right pulmonary artery plus the diameter of the left pulmonary artery to the diameter of the descending thoracic aorta was inversely related to the initial ratio[r=0.757, p >0.001], but the change in the ratio of the diameter of the main pulmonary artery to the descending thoracic aorta was not related[r=0.059, p >0.05]. 5. There were no differences in enlargement of the pulmonary artery on the side of the shunt [ipsilateral] versus enlargement on the opposite side [p >0.05], nor according to the size of the shunt[p >0.05]. In conclusion, this study suggests that the Blalock-Taussig shunt is effective for the development of the right and left pulmonary arteries but not effective for the main pulmonary artery.

• Journal of Chest Surgery
• /
• v.21 no.1
• /
• pp.10-16
• /
• 1988

Ten patients with tetralogy of Fallot were studied angiocardiographically before a modified Blalock-Taussig shunt and again 25*3.2 months after the previous shunt. All of ten patients had patent previous shunt at the time of follow up examination. Pre-and postoperative diameters of left and right pulmonary artery and descending aorta were measured and pulmonary artery index [the sum of the crossectional areas of the right and left pulmonary arteries standardized by the body surface area] was calculated. The ratio of mean diameter of left and right pulmonary arteries to the diameter of the descending aorta [LPA+RPA/2xDA] was increased postoperatively by 0.20*0.068 [p=0.020]. Mean PAI [pulmonary artery index] increased from 283.8*178.4 mm/m2 BSA to 345.8~144.5 mm/m2 BSA after shunt operation [p=0.019]. This results suggested that the modified Blalock-Taussig shunt was effective to help growth of the pulmonary arteries in most cases of the study populations but the ones with the PAI>233mm*/m* BSA appeared less benefited by Blalock Taussig shunt. Calculation of PAI could be an aid to making a decision whether to perform a one stage corrective surgical procedure or a palliative shunt procedure in the patient with small pulmonary arteries.

• Journal of Chest Surgery
• /
• v.28 no.11
• /
• pp.983-988
• /
• 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 Korean Neurosurgical Society
• /
• v.65 no.4
• /
• pp.582-590
• /
• 2022

Objective : Hydrocephalus after intracerebral hemorrhage (ICH) is known to be related to poor prognosis and mortality. We analyzed predictors of permanent hydrocephalus in the patients with surgically treated supratentorial ICH. Methods : From 2004 to 2019, a total of 414 patients with surgically treated primary supratentorial ICH were included. We retrospectively analyzed age, sex, preexisting hypertension and diabetes, location and volume of ICH, presence and severity of intraventricular hemorrhage (IVH), and type of surgery. Results : Forty patients (9.7%) required shunt surgery. Concomitant IVH was higher in the 'shunt required' group (92.5%) than in the 'shunt not required' group (67.9%) (p=0.001). IVH severity was worse in the 'shunt required' group (13.5 vs. 7.5, p=0.008). Craniectomy (47.5%) was significantly high in the 'shunt required' group. According to multivariable analysis, the presence of an IVH was 8.1 times more frequent and craniectomy was 8.6 times more frequent in the 'shunt required' group. In the comparison between craniotomy and craniectomy group, the presence of an IVH was related with a 3.9 times higher (p=0.033) possibility and craniectomies rather than craniotomies with a 7-times higher possibility of shunt surgery (p<0.001). Within the craniectomy group, an increase in the craniectomy area by 1 cm² was correlated with a 3.2% increase in the possibility of shunt surgery (odds ratio, 1.032; 95% confidence interval, 1.005-1.061; p=0.022). Conclusion : Presence of IVH, the severity of IVH and decompressive craniectomy were related to the development of shunt dependent hydrocephalus in the patients with ICH. The increasing size of craniectomy was related with increasing rate of shunt requirement.

• Journal of Mechanical Science and Technology
• /
• v.15 no.7
• /
• pp.1061-1071
• /
• 2001

The present study investigated design parameters of shunt valves and anti-siphon device used to treat patients with hydrocephalus. The shunt valve controls drainage of cerebrospinal fluid (CSF) through passive deflection of a thin and small diaphragm. The anti-siphon device(ASD) is optionally connected to the valve to prevent overdrainage when the patients are in the standing position. The major design parameters influencing pressure-flow characteristics of the shunt valve were analyzed using ANSYS structural program. Experiments were performed on the commercially available valves and showed good agreements with the computer simulation. The results of the study indicated that predeflection of the shunt valve diaphragm is an important design parameter to determine the opening pressure of the valve. The predeflection was found to depend on the diaphragm tip height and could be adjusted by the diaphragm thickness and its elastic modulus. The major design parameters of the ASD were found to be the clearance (gap height) between the thin diaphragm and the flow orifice. Besides the gap height, the opening pressure of the ASD could be adjusted by the diaphragm thickness, its elastic modulus, area ratio of the diaphragm to the flow orifice. Based on the numerical simulation which considered the increased subcutaneous pressure introduced by the tissue capsule pressure on the implanted shunt valve system, optimum design parameters were proposed for the ASD.

• The Korean Journal of Nuclear Medicine
• /
• v.13 no.1_2
• /
• pp.7-14
• /
• 1979

Radionuclide cardiac angiography has distinct advantages in safety, patient comfort, cost and ease of performance. This method offers diagnostic accuracy equivalent to that of cardiac catheterization. By this method the qualitative and quantitative diagnosis of the cardiac shunts are available. Also for it is repeatable with ease and more physiologic, it has application in following pre- and post-operative shunt patients. We performed the radionuclide cardiac angiographies in 147 cases of heart diseases and 26 cases of normal group. 1. The detection of left-to-right shunt was possible in 22 of 24 patients, and 2 patients were not diagnosed due to small shunt amount. (Qp/Qs<1.3) In 21 patients of right-to-left shunt, all were diagnosed by radionuclide cardiac angiography. 2. With the pulmonary time-activity curve, $C_2/C_1$ ratio was calculated. In normal control group, a range of $C_2/C_1$ ratios of $21{\sim}38%$ was established with a mean value of $28.6{\pm}4.6%$. In patients with left-to-right shunts determined by catheterization data, the range of $C_2/C_1$ ratio was $33{\sim}90%$, with a mean value of $67.8{\pm}12.2%$. 3. In 8 cases of left-to-right shunt, $Q_p/Q_s$ ratios determined by radionuclide cardiac angiography were compaired with those of cardiac catheterization. The correlation coefficient was 0.907. (P<0.001) 4. Postoperative radionuclide cardiac angiographies were done in 21 cases. 3 of 13 patients with left-to-right shunts were found to have residual shunts. 8 patients with right-to-left shunts were confirmed to have no residual shunt.