• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1096-1106
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• 2013

This paper presents the control of a Permanent Magnet Electric Variable Transmission (PM-EVT) for Hybrid Electric Vehicles (HEVs). Consisting of two electric machines, the EVT realizes the power split function in an electromagnetic way rather than in a mechanical way. A specific PM-EVT has been designed for Toyota Prius II. The control scheme of the entire vehicle is deduced using the Energetic Macroscopic Representation methodology. The energy management strategy yields local control references. A specific attention is paid for the field weakening for wide speed range. Simulation results are provided to illustrate the EVT modeling and control.

• Journal of Korean Neurosurgical Society
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• v.62 no.2
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• pp.193-200
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• 2019

Objective : Endovascular treatment (EVT) outcomes for acute M2 segment of middle cerebral artery occlusion remains unclear because most results are obtained from patients with large artery occlusion in the anterior circulation. The objective of this study was to assess procedural outcomes for acute M2 occlusion and compare outcomes according to thrombus location (M1 vs. M2). Methods : A systematic review was performed for online literature published from January 2004 to December 2016. Primary outcome was successful recanalization rate and symptomatic intracranial hemorrhage (S-ICH) after the procedure. A fixed effect model was used if heterogeneity was less than 50%. Results : Eight articles were included. EVT showed successful recanalization rate of 69.1% (95% confidence interval [CI], 54.9-80.4%) and S-ICH rate of 6.1% (95% CI, 4.5-8.3%). The rates of good clinical outcome at 3 months and mortality were 59.4% (95% CI, 49.9-68.2%) and 14.9% (95% CI, 11.4-19.3%), respectively. According to thrombus location (M1 vs. M2), successful recanalization (odds ratio [OR], 1.539; 95% CI, 0.293-8.092; p=0.610) and S-ICH (OR, 1.313; 95% CI, 0.603-2.861; p=0.493) did not differ significantly. Good clinical outcome was more evident in M2 occlusion after EVT than that in M1 occlusion (OR, 1.639; 95% CI, 1.135-2.368; p=0.008). However, mortality did not differ significantly according to thrombus location (OR, 0.788; 95% CI, 0.486-1.276; p=0.332). Conclusion : EVT seems to be technically feasible for acute M2 occlusion. Direct comparative studies between EVT and medical treatment are needed further to find specific beneficiary group after EVT in patient with M2 occlusion.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.353-358
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• 2022

Bulky iron-core potential transformers (PT) are installed in a tank of gas insulated switchgears (GIS) for a system voltage measurement in power substations. In this paper, we studied an electronic voltage transformer (EVT) embedded in a spacer for miniaturization, eco-friendliness, and performance improvement of GIS. The prototype EVT consists of a capacitive probe (CP) that can be embedded in a spacer and a voltage Follower with a high input and a low output impedance. The CP was fabricated in the form of a Flexible-PCB to acquire the insulation performance and to withstand vibration and shock during operation. Voltage ratio of the prototype EVT is about 42,270, and the frequency bandwidth of -3 dB ranges from 0.33 Hz to 3.9 MHz. The voltage ratio error evaluated at about 6%, 12% and 18% of the rated voltage of 170 kV was 0.32%, and the phase error was 12.9 minutes. These results were within the accuracy for the class 0.5 specified in IEC 60044-7 and satisfy even in ranges from 80% to 120% of the rated voltage. If the prototype EVT replaces the conventional iron-core potential transformer, it is expected that the height of the GIS could be reduced by 11% and the amount of SF₆ will be reduced by at least 10%.

• Journal of Chest Surgery
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• v.57 no.2
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• pp.152-159
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• 2024

Background: Anastomotic leakage (AL) following esophagectomy represents a serious complication that often results in prolonged hospitalization and necessitates repeated interventions, including nothing-by-mouth (NPO) restriction, endoscopic vacuum therapy (EVT), or surgical repair. In this study, we evaluated the patterns and outcomes of AL treatment. Methods: We retrospectively reviewed the medical records of patients who underwent esophagectomy for esophageal cancer at a single center between 2003 and 2020. Of 3,096 examined cases, 181 patients (5.8%) with AL were included in the study: 114 patients (63%) with cervical anastomosis (CA) and 67 (37%) with intrathoracic anastomosis (TA). Results: The incidence of AL was 11.9% in the CA and 3.2% in the TA group (p<0.001). Among patients with CA who developed AL, 87 (76.3%) were managed with NPO, 15 (13.2%) with EVT, and 12 (10.5%) with surgical repair. Over 90% of patients with cervical AL resumed an oral diet by the time of discharge, regardless of treatment method. Among patients with TA and AL, 36 (53.7%) received NPO, 25 (37.7%) underwent EVT, and 6 (9%) required surgery. Of these, 34 patients who were managed with NPO and 19 with EVT could resume an oral diet. However, only 2 patients who underwent surgery resumed an oral diet, and 2 patients required additional EVT. Conclusion: Although patients with CA displayed a higher incidence of AL, their rate of successful oral intake exceeded that of those with TA, regardless of treatment method. Among patients exhibiting AL with TA, EVT was more commonly employed than in CA cases, and it appears effective.

• Journal of Neurocritical Care
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• v.11 no.2
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• pp.93-101
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• 2018

Background: At most centers, general anesthesia (GA) has been preferred for endovascular treatment (EVT) of ruptured intracranial aneurysms (RIAs). In this study, we analyzed procedural results, clinical outcomes, and follow-up angiographic findings for patients undergoing EVT for RIA under local anesthesia (LA) with conscious sedation (CS). Methods: We retrospectively evaluated 308 consecutive patients who underwent EVT for RIAs at a single institution between June 2009 and February 2017. EVT under LA with CS was considered for all patients with aneurysmal subarachnoid hemorrhage, regardless of Hunt and Hess (HH) scale score. Results: EVT was performed for 320 aneurysms in 308 patients with subarachnoid hemorrhages. The mean patient age was $55.5{\pm}12.6$ years. Moderate (III) and poor (IV, V) HH grades were observed in 75 (24.4%) and 77 patients (25%), respectively. Complete occlusion immediately after EVT was achieved for 270 (84.4%) of 320 aneurysms. Thromboembolic complications and intraprocedural ruptures occurred in 25 (7.8%) and 14 cases (4.3%), respectively. The morbidity rate at discharge (as defined by a modified Rankin scale score of 3 or greater) was 27.3% (84/308), while the mortality rate was 11.7% (36/308). Follow-up angiographic results were available for 210 (68.1%) of 308 patients. Recanalization was observed in 64 (29.3%) of 218 aneurysms in 210 patients. Conclusion: Based on our experience, EVT for RIAs under LA with CS was feasible, regardless of the clinical grade of the subarachnoid hemorrhage. Complication rates and follow-up angiographic results were also comparable to those observed when GA was used to perform the procedure.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.59-63
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• 2007

Operative clipping after previous endovascular coiling in an aneurysm is a different problem from primary clipping procedure for neurosurgeons. With the increasing use of coil embolization, neurosurgeons will more and more face the similar situation. We report surgical clipping cases of intracranial aneurysm regrown after endovascular coiling. Three patients with a history of subarachnoid hemorrhage due to ruptured aneurysm underwent endovascular treatment (EVT) with detachable coils. The aneurysms were in the posterior communicating artery, the middle cerebral artery and distal anterior cerebral artery (DACA). Two near-total occlusions and one partial occlusion were achieved by EVT. After several months, angiographic follow-up revealed regrowth of the aneurysm requiring surgical clipping. Here, we report three cases in which surgical clipping was more difficult than a usual clipping procedure performed several months after EVT, because of adhesion and coil bulging into the aneurysmal neck. The difficulty of the treatment of the residual aneurysm after coiling is discussed, as are the surgical complications and limitations of clipping.

• Clinical Endoscopy
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• v.55 no.1
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• pp.58-66
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• 2022

Background/Aims: Anastomotic leakage after esophageal surgery remains a feared complication. During the last decade, management of this complication changed from surgical revision to a more conservative and endoscopic approach. However, the treatment remains controversial as the indications for conservative, endoscopic, and surgical approaches remain non-standardized. Methods: Between 2010 and 2020, all patients who underwent Ivor Lewis esophagectomy for underlying malignancy were included in this study. The data of 28 patients diagnosed with anastomotic leak were further analyzed. Results: Among 141 patients who underwent resection, 28 (19.9%) developed an anastomotic leak, eight (28.6%) of whom died. Thirteen patients were treated with endoluminal vacuum therapy (EVT), seven patients with self-expanding metal stents (SEMS) four patients with primary surgery, one patient with a hemoclip, and three patients were treated conservatively. EVT achieved closure in 92.3% of the patients with a large defect and no EVT-related complications. SEMS therapy was successful in clinically stable patients with small defect sizes. Conclusions: EVT can be successfully applied in the treatment of anastomotic leakage in critically ill patients, while SEMS should be limited to clinically stable patients with a small defect size. Surgery is only warranted in patients with sepsis with graft necrosis.

• Journal of Korean Neurosurgical Society
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• v.67 no.1
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• pp.31-41
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• 2024

Objective : Collateral circulation is associated with the differential treatment effect of endovascular thrombectomy (EVT) in acute ischemic stroke. We aimed to verify the ability of the collateral map to predict futile EVT in patients with acute anterior circulation ischemic stroke. Methods : This secondary analysis of a prospective observational study included data from participants underwent EVT for acute ischemic stroke due to occlusion of the internal carotid artery and/or the middle cerebral artery within 8 hours of symptom onset. Multiple logistic regression analyses were conducted to identify independent predictors of futile recanalization (modified Rankin scale score at 90 days of 4-6 despite of successful reperfusion). Results : In a total of 214 participants, older age (odds ratio [OR], 2.40; 95% confidence interval [CI], 1.56 to 3.67; p<0.001), higher baseline National Institutes of Health Stroke Scale (NIHSS) scores (OR, 1.12; 95% CI, 1.04 to 1.21; p=0.004), very poor collateral perfusion grade (OR, 35.09; 95% CI, 3.50 to 351.33; p=0.002), longer door-to-puncture time (OR, 1.08; 95% CI, 1.02 to 1.14; p=0.009), and failed reperfusion (OR, 3.73; 95% CI, 1.30 to 10.76; p=0.015) were associated with unfavorable functional outcomes. In 184 participants who achieved successful reperfusion, older age (OR, 2.30; 95% CI, 1.44 to 3.67; p<0.001), higher baseline NIHSS scores (OR, 1.12; 95% CI, 1.03 to 1.22; p=0.006), very poor collateral perfusion grade (OR, 4.96; 95% CI, 1.42 to 17.37; p=0.012), and longer door-to-reperfusion time (OR, 1.09; 95% CI, 1.03 to 1.15; p=0.003) were associated with unfavorable functional outcomes. Conclusion : The assessment of collateral perfusion status using the collateral map can predict futile EVT, which may help select ineligible patients for EVT, thereby potentially reducing the rate of futile EVT.

• Korean Circulation Journal
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• v.52 no.6
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• pp.429-440
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• 2022

Background and Objectives: Endovascular therapy (EVT) first strategy has been widely adopted for the treatment of chronic limb threatening ischemia (CLTI) patients in real-world practice. This study aimed to investigate long-term outcomes of CLTI patients who underwent EVT and identify prognostic factors. Methods: From the retrospective cohorts of a Korean multicenter endovascular therapy registry, 1,036 patients with CLTI (792 men, 68.8 ± 9.5 years) were included. The primary endpoint was amputation-free survival (AFS) defined as the absence of major amputation or death. Secondary endpoints were major adverse limb events (MALE; a composite of major amputation, minor amputation, and reintervention). Results: Five-year AFS and freedom from MALE were 69.8% and 61%, respectively. After multivariate analysis, age (hazard ratio [HR], 1.476; p<0.001), end-stage renal disease (ESRD; HR, 2.340; p<0.001), Rutherford category (RC) 6 (HR, 1.456; p=0.036), and suboptimal EVT (HR, 1.798; p=0.005) were identified as predictors of major amputation or death, whereas smoking (HR, 0.594; p=0.007) was protective. Low body mass index (HR, 1.505; p=0.046), ESRD (HR, 1.648; p=0.001), femoropopliteal lesion (HR, 1.877; p=0.004), RC-6 (HR, 1.471; p=0.008), and suboptimal EVT (HR, 1.847; p=0.001) were predictors of MALE. The highest hazard rates were observed during the first 6 months for both major amputation or death and MALE. After that, the hazard rate decreased and rose again after 3-4 years. Conclusions: In CLTI patients, long-term outcomes of EVT were acceptable. ESRD, RC-6, and suboptimal EVT were common predictors for poor clinical outcomes.

• Cement Symposium
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• s.34
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• pp.150-159
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• 2007