• Journal of Korean Neurosurgical Society
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• v.39 no.5
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• pp.347-354
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• 2006

Objective : We evaluate the role of multislice computerized tomographic angiography[MCTA] in the diagnosis of intracranial vasospasm following subarachnoid hemorrhage[SAH] in patients suspected of having vasospasm on clinical ground. Methods : Between October 2003 and June 2005, patients with ruptured cerebral aneurysms of the anterior circulation clipped within 3 days of the onset were included. We performed follow-up MCTAs in patients who were suspected to have vasospasm on transcranial doppler sonography[TCD] findings and clinical grounds. Based on the clinical presentation of symptomatic vasospasm, we investigated the correlation between clinical, TCD, and MCTA signs of vasospasm and evaluated the role of MCTA in vasospasm. Results : One hundred one patients met the inclusion criteria and symptomatic vasospasm developed in 25 patients [24.8%]. We performed follow-up MCTAs in 28 patients. MCTA revealed spasm in the vessels of 26 patients. The sensitivity of MCTA was 100%. Among the 26 patients with MCTA evidence of vasospasm, 3 patients had TCD signs of vasospasm after symptomatic vasospasm presentation. Another 3 patients with symptomatic vasospasm had no TCD signs of vasospasm in daily serial recordings. Six other patients without symptomatic vasospasm showed MCTA evidence of vasospasm [false positive result] but these patients had also positive TCD signs of vasospasm. Volume rendering[VR] images tended to show significantly more exaggerated vasospasm than maximum intensity projection[MIP] images. The mean cerebral blood flow velocity of both proximal segment of the middle cerebral artery [M1] was significantly correlated with each reduced M1 diameter on MCTA [P<005]. Conclusion : MCTA could be a useful tool for evaluation and planning management of critically ill patients suspected of having vasospasm; however, more randomized controlled trials are necessary to assess these points definitively.

• 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.30 no.3
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• pp.325-333
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• 2001

Objective : To clarify the benefits and therapeutic effects of intra-arterial papaverine infusion on the symptomatic cerebral vasospasm, we analyzed the results of treatment in 32 patients retrospectively. Methods : A total of 510 patients underwent surgical clipping or endovascular intra-aneurysmal treatment for ruptured intracranial aneurysm between May, 1996 and June, 1999. The delayed ischemic deficit(DID) was developed in 90 of 510 patients. Of these 90 patients, 32 developed symptomatic vasospasm inspite of using modest "3H therapy". The brain CT scan was taken before the intra-arterial infusion of papaverine. The 32 patients underwent 42 intra-arterial papaverine infusion. The symptomatic vasospasm was divided into three groups : deterioration of mental status(Group 1), appearance of a focal neurologic deficit(Group 2), or both(Group 3). We measured Glasgow Coma Scale(GCS), arterial diameters, and cerebral circulation time(CCT) at the time of pre- and postangioplasty. Results : The number of patients in group 1, 2 and 3 were 26, 7, 9 respectively. Eighteen cases showed improvement of GCS more than 2 scores, 16 more than 1, and 8 showed no change of GCS. Average cerebral circulation time(CCT) was decreased ranging from 0.0%-67.5%, and arterial diameters were increased in 21 cases ranging from 1 to 4 folds. Conclusion : Intra-arterial papaverine infusion seemed to have therapeutic effects on symptomatic vasospasm by improving the neurological signs and increasing the arterial diameter. We suggest that intra-arterial papaverine infusion would be an useful adjunctive therapeutic modality in symptomatic vasospasm.

• Journal of Korean Neurosurgical Society
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• v.42 no.2
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• pp.103-111
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• 2007

Objective : We evaluated the accuracy of multislice computerized tomographic angiography (MCTA) in the postoperative evaluation of clipped aneurysms by comparising it with three dimensional digital subtraction angiography (3D-DSA). Methods : Between May 2004 and September 2006, we included patients with ruptured cerebral aneurysm of the anterior circulation that was surgically clipped and evaluated by both postoperative MCTA and postoperative 3D-DSA. We measured the diagnostic performance and calculated the sensitivity and specificity of postoperative MCTA compared to 3D-DSA in the detection of aneurysm remnants. Results : A total of 11 neck remnants among the 92 clipped aneurysms (11.9%) were confirmed by 3D-DSA. According to Sindou's classification of aneurysm remnants, 8.7% of clipped aneurysms (8/92) had only neck remnant on 3D-DSA and 3.2% (3/92 aneurysms) had residuum of the neck and sac on 3D-DSA. There were 12 (13.04%) equivocal cases that were difficult to interpret based on the postoperative MCTA. The reasons for the equivocal cases included multiple clips (6 cases, 50.0%). beam-hardening effect (4 cases, 33.3%), motion artifact (1 case, 8.3%), fenestrated clip (1 case, 8.3%) and other combined causes. The sensitivity and specificity of the postoperative MCTA was 81.8% and 88.9%, respectively by ROC curve (p=0.000). Conclusion : MCTA is an accurate noninvasive imaging method used for the assessment of clipped aneurysms in the anterior circulation. If the image quality of postoperative MCTA is good quality and the patient has been treated with a single titanium clip, except a fenestrated clip, the absence of an aneurysm remnant can be diagnosed by MCTA alone and the need for postoperative DSA can be reduced in a large percentage of cases.

• Journal of Korean Neurosurgical Society
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• v.45 no.1
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• pp.5-10
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• 2009

Objective : Direct surgical clipping of paraclinoid aneurysms poses technical challenges to even very experienced neurosurgeons, making endovascular treatment an alternative treatment modality in many centers. We have therefore retrospectively evaluated the safety and efficacy of endovascular detachable coil embolization of paraclinoid aneurysms. Methods : From June 1997 to June 2007, 65 patients underwent endovascular detachable coiling for 67 paraclinoid aneurysms (of which 9 were ruptured and 58 were unruptured) in our institute. Their medical records, radiological images and readings, and operation records were reviewed retrospectively. Results : After the initial embolization procedure, complete occlusion was achieved in 29 (43.3%) of the aneurysms treated by endovascular detachable coiling. Six aneurysms required retreatment, with two each requiring one, two, or three additional endovascular procedures. Fifty-five (82.1%) aneurysms were measured by three-dimensional time of flight (TOF) magnetic resonance images (MRI) or transfemoral cerebral angiography (TFCA) at a mean follow-up of 29.7 months (range from 4 to 94 months), with 39 aneurysms (70.9%) showing complete occlusion. Thromboembolic events (3.8%) were the most frequent complication. Rupture did not occur during or after any of the procedures. According to the Glasgow Outcome Scale (GOS), 98.4% of the patients treated by coil embolization had a score of 4 or 5. Conclusion : Our results indicate that endovascular detachable coiling is a safe and effective treatment modality in paraclinoid aneurysms.

• Journal of Korean Neurosurgical Society
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• v.48 no.4
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• pp.330-334
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• 2010

Objective : Residual aneurysm from incomplete clipping or slowly recurrent aneurysm is associated with high risk of subarachnoid hemorrhage. We describe complete treatment of the lesions by surgical clipping or endovascular treatment. Methods : We analyzed 11 patients of residual or recurrent aneurysms who had undergone surgical clipping from 1998 to 2009. Among them, 5 cases were initially clipped at our hospital. The others were referred from other hospitals after clipping. The radiologic and medical records were retrospectively analyzed. Results : All patients presented with subarachnoid hemorrhage at first time, and the most frequent location of the ruptured residual or recurrent aneurysm was in the anterior communicating artery to posterior-superior direction. Distal anterior cerebral artery, posterior communicating artery, and middle cerebral artery was followed. Repositioning of clipping in eleven cases, and one endovascular treatment were performed. No residual aneurysm was found in postoperative angiography, and no complication was noted in related to the operations. Conclusion : These results indicate the importance of postoperative or follow up angiography and that reoperation of residual or slowly recurrent aneurysm should be tried if such lesions being found. Precise evaluation and appropriate planning including endovascular treatment should be performed for complete obliteration of the residual or recurrent aneurysm.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.186-194
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• 2007

This study was performed to compare the load-carrying capacities of the reinforced concrete structure between the carbon fiber adhesion reinforcement method and the external post-tensioning method and further estimate the effective stress of the reinforced material by analyzing the experimental reinforcing effect of each method and the behavior resulting from each method. As a result, it was found out that the effective stress of the carbon fiber reinforcement according to the carbon fiber adhesion reinforcement method had an unexpected value, and also, bearing of the stress was found to be far from sharing thereof. That is to say, while the carbon fiber was bearing the whole stress to some limits, it got to be momentarily ruptured as soon as it went beyond such limits. On the other hand, the external post-tensioning method has the advantage of inducing an initial effective stress by introducing a strain, and thus, it was found that behavior or bearing of the stress was also found to be a solid behavior of the steel wire. This method was also found to be more efficient and excellent than the carbon fiber adhesion reinforcement method in the reinforcing effect or securing the effective stress. Accordingly, we were to discuss the effective stress as comparatively examined, focusing on deriving of the more enhanced reinforcing effect on the basis of the experiment to which the field characteristic is added.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.17-25
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• 2010

This paper studied on stability of the U-channel segmental concrete bridge under vehicle-impact loads. The U-channel bridge has advantages in that it reduces an additional dead load and the edge beams role as a barrier. But it has a dangerous factor which collapses the bridge structure when the edge beams are ruptured. Therefore, it is necessary to verify behaviors of the bridge system under vehicle-impact loads. Static and dynamic vehicle impact simulations were carried out on the basis of AASHTO LRFD design specifications. In case of the static analysis, equivalent static loads specified in the AASHTO codes are loaded on the edge beams and in case of the dynamic analysis, FEM vehicle models are modeled by applying the dynamic test specifications of AASHTO codes. As a result, it is shown that U-channel bridge system has sufficient safety against static and dynamic impact loads specified in the AASHTO LRFD design specifications.

• Journal of Korean Neurosurgical Society
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• v.59 no.1
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• pp.11-16
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• 2016

Objective : We conducted a retrospective cohort study to elucidate the natural course of unruptured intracranial aneurysms (UIAs) at a single institution. Methods : Data from patients diagnosed with UIA from March 2000 to May 2008 at our hospital were subjected to a retrospective analysis. The cumulative and annual aneurysm rupture rates were calculated. Additionally, risk factors associated with aneurysmal rupture were identified. Results : A total of 1339 aneurysms in 1006 patients met the inclusion criteria. During the follow-up period, 685 aneurysms were treated before rupture via either an open surgical or endovascular procedure. Six hundred fifty-four UIAs were identified and not repaired during the follow-up period. The mean UIA size was $4.5{\pm}3.2mm$, and 86.5% of the total UIAs had a largest dimension <7 mm. Among these UIAs, 18 ruptured at a median of 1.6 years (range : 27 days to 9.8 years) after day 0. The annual rupture risk during a 9-year follow-up was 1.00%. A multivariate Cox proportional hazards analysis revealed that the aneurysm size and a history of subarachnoid hemorrhage (SAH) were statistically significant risk factors for rupture. For an aneurysms smaller than 7 mm in the absence of a history of SAH, the annual rupture risk was 0.79%. Conclusion : In our study, the annual rupture risk for UIAs smaller than 7 mm in the absence of a history of SAH was higher than that of Western populations but similar to that of the Japanese population.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.755-763
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• 2020

The critical flow phenomenon has been studied because of its significant effect for design basis accidents in nuclear power plants. Transition points from thermal non-equilibrium to equilibrium are different according to the geometric effect on the critical flow. This study evaluates the uncertainty parameters of the critical flow model for analysis of DBA (Design Basis Accident) with the MARS-KS (Multi-dimensional Analysis for Reactor Safety-KINS Standard) code used as an independent regulatory assessment. The uncertainty of the critical flow model is represented by three parameters including the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio, and their ranges are determined using large-scale Marviken test data. The uncertainty range of the thermal non-equilibrium factor is updated by the MCDA (Model Calibration through Data Assimilation) method. The updated uncertainty range is confirmed using an LBLOCA (Large Break Loss of Coolant Accident) experiment in the LOFT (Loss of Fluid Test) facility. The uncertainty ranges are also used to calculate an LBLOCA of the APR (Advanced Power Reactor) 1400 NPP (Nuclear Power Plants), focusing on the effect of the PCT (Peak Cladding Temperature). The results reveal that break flow is strongly dependent on the degree of the thermal non-equilibrium state in a ruptured pipe with a small L/D ratio. Moreover, this study provides the method to handle the thermal non-equilibrium factor, discharge coefficient, and length to diameter (L/D) ratio in the system code.