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Objective : Despite many advancements in endovascular treatment, the benefits of mechanical thrombectomy (MT) in patients with large infarctions remain uncertain due to hemorrhagic complications. Therefore, we aimed to investigate the efficacy and safety of recanalization via MT within 6 hours after stroke in patients with large cerebral infarction volumes (>70 mL).Methods : We retrospectively reviewed the medical data of 30 patients with large lesions on initial diffusion-weighted imaging (>70 mL) who underwent MT at our institution within 6 hours after stroke onset. Baseline data, recanalization rate, and 3-month clinical outcomes were analyzed. Successful recanalization was defined as a modified treatment in cerebral ischemia score of 2b or 3.Results : The recanalization rate was 63.3%, and symptomatic intracerebral hemorrhage occurred in six patients (20%). The proportion of patients with modified Rankin Scale (mRS) scores of 0–3 was significantly higher in the recanalization group than in the non-recanalization group (47.4% vs. 9.1%, p=0.049). The mortality rate was higher in the non-recanalization group, this difference was not significant (15.8% vs. 36.4%, p=0.372). In the analysis of 3-month clinical outcomes, only successful recanalization was significantly associated with mRS scores of 0–3 (90% vs. 50%, p=0.049). The odds ratio of recanalization for favorable outcomes (mRS 0–3) was 9.00 (95% confidence interval, 0.95–84.90; p=0.055).Conclusion : Despite the risk of symptomatic intracerebral hemorrhage, successful recanalization via MT 6 hours after stroke may improve clinical outcomes in patients with large vessel occlusion.

We report on the development of a highly conductive, transparent and flexible Ag mesh-like network covered by an ITO/PEDOT:PSS nanocomposite for flexible conductive electronics. The electrode was deposited completely via solution-based deposition. A lower Rs value, from 7.21 Ω/□ to 5.05 Ω/□, was achieved by annealing the substrate via low-temperature plasma annealing. The low-temperature annealing was used to achieve crystallinity of the materials without deformation and degradation of PEDOT:PSS and the PET substrate. The low-cost deposition-based Ag NW-ITO/PEDOT:PSS electrode substantially decreased sheet resistance and provides the transmittance of 85.17%. The chemical stability and mechanical stability of the product were examined, and morphological studies were performed; in all of these, the substrate exhibited excellent behavior. Finally, a transparent flexible electrical heater and capacitive touch screen panel were fabricated using the Ag NW-ITO/PEDOT:PSS electrode to demonstrate the performance of the electrode and its potential applications.

This paper studied the resonant behaviors of a bottom-hinged oscillating wave surge converter (OWSC) as well as the relationship of resonance with the response and capture width ratio (CWR). The time-domain dynamic equation of an OWSC in shallow water based on the boundary element method (BEM) was solved by a Python code, considering the corrected wave surface and the nonlinearities of restoring moment, drag, and friction. The unknown factors, such as wave surface corrected factor and drag coefficient, were effectively calibrated with computational fluid dynamics (CFD) method. An intermediate initial angle in free decay is appropriate for use to determine the natural period. Under regular waves, the resonance occurs near the natural period for the uniform wave amplitude, rather than the uniform wave torque amplitude, and can disappear due to the amplification of Power Take-Off (PTO) friction. Under unit-amplitude regular waves, the period of maximum CWR is relatively close to the period of maximum velocity, but far from the resonant period. Under irregular waves, no stable resonance is observed because the maximum equivalent pitch angle appears at different peak periods of wave spectra with the variation in PTO damping. When the period of a regular wave or the peak period of an irregular wave is close to the natural period, a phase hysteresis of velocity relative to wave torque always occurs.

The effect of separation on the fracture surface of ferrite–bainite dual-phase pipeline steels during a drop weight tear test (DWTT) was investigated via microstructural analysis and fracture surface examination. Two specimens (ST1 and ST2) were designed to have a dual-phase microstructure, with different ferrite and bainite fractions, by controlling the reduction ratio and holding time in the ferrite–austenite two-phase region during the thermomechanical process. Notably, ST2, which had a longer holding time for the retained austenite to absorb carbon, exhibited a harder bainite but softer ferrite phase compared to ST1. The greater hardness difference between those phases in ST2 induced the strain incompatibility frequently evident at the phase boundaries, resulting in lower ductility during the tensile test. Owing to the strain incompatibility, ST2 also generated more separation over a wider temperature range during DWTT. At low temperatures, where the brittle fracture was prominent, it was observed that ST2 generated separations on its fracture surface, whereas ST1 did not. These separations formed a local shear lip around themselves, thereby obstructing cleavage fracture propagation from the notch. Hence, it was confirmed that ST2 had a higher DWTT shear area than ST1 over a temperature range near the ductile–brittle transition temperature (DBTT). As a result, the DBTT of ferrite–bainite dual phase steel could be improved by increasing the amount of separation during DWTT.

We report on the development of a cost effective, highly transparent flexible conductive electrode for energy conversion devices using the ITO/PEDOT:PSS nanocomposite. The ITO/PEDOT:PSS nano composite thin film was deposited via bar coating, then its characteristics were examined. In particular, we study any changes in its transparency and resistance. The thin film transparent ITO/PEDOT:PSS was annealed using a low temperature annealing technique called plasma annealing. The purpose of low temperature plasma annealing is to help excite the electrons from their bonding states in the valence band into the antibonding states of the conduction band where a second order phase transition occurs. This study investigates the influence of O2 plasma annealing on the resistance of the nano composite thin films. The included PEDOT:PSS supports the flexibility of the ITO, as pristine ITO is brittle. High optical transmittance of 93.73% at 550 nm and a reduction in the sheet resistance were achieved using this plasma annealing from 1105 Ω/□ to 535 Ω/□ on the ITO/PEDOT:PSS nano composite making them excellent candidates to develop as cost effective flexible transparent electrodes that can be used as thin film heaters.

Background The unilateral anterior interhemispheric approach has been widely used for distal anterior cerebral artery (DACA) aneurysms. However, there are some drawbacks of this approach because of the narrow operative field, including possible brain traction injury, bridging vein injury, and inadequate exposure of the aneurysm. Here, we report a case of a DACA aneurysm covered by the falx that could not be totally exposed with the unilateral interhemispheric approach. We successfully obtained a wide view with wedge resection of the falx, avoiding excessive brain traction and division of the superior sagittal sinus. Case Description A 76-year-old woman with a 6-mm unruptured DACA aneurysm underwent a unilateral craniotomy with the anterior interhemispheric approach. In the operative field, the aneurysm was found at the midline, just below the falx. The aneurysm was covered by the falx and could not be completely exposed with the usual brain retraction. Therefore, we performed wedge resection of the falx, thus obtaining sufficient surgical field and totally exposing the aneurysm. We were then able to apply the clip successfully. Postoperative brain computed tomography angiography showed no remnant aneurysm sac or complications of falx resection or brain retraction, such as bleeding or vessel injury. Conclusions When an aneurysm is located just below the falx and is exposed inadequately, performing wedge resection of the falx can expose the aneurysms adequately for application of the clip.

Background In patients with intracerebral hemorrhage (ICH), brain volume loss can occur in the hemisphere ipsilateral to the hematoma. However, contralateral hemispheric volume change after ICH is not well known. The present study aimed to investigate contralateral brain volume changes in patients with ICH who had not undergone surgery. Methods Of the 2213 patients with ICH admitted to our hospital between January 2010 and December 2017, 46 patients without surgical intervention were included in the present study. We measured contralateral hemispheric brain volume in the axial images of brain computed tomography at the time of ICH onset and after 12 months. We analyzed the relationship between various factors and volume changes in the contralateral hemisphere. Results The mean change percentage between the initial and follow-up contralateral parenchyma volume was 96.84%. The average volume decreased by 3.16% (P = 0.001). Univariate and multivariate logistic regression models revealed no significant factors associated with contralateral brain volume loss. Kruskal–Wallis test and Mann–Whitney U test showed no statistical significance (P = 0.824, P = 0.122) between ICH volume groups. Conclusions Contralateral parenchymal volumes were significantly decreased at follow-up brain computed tomography scanning; these changes may provide important clinical information on the remote effect of focal lesion and symptoms in the course of ICH treatment. However, further investigation is required to determine the mechanisms underlying these volume changes.

Objective : High-dose radiation is well known to induce and modulate the immune system. This study was performed to evaluate the correlation between clinical outcomes and changes in natural killer cell activity (NKA) after Gamma Knife Radiosurgery (GKS) in patients with brain cancer.Methods : We performed an open-label, prospective, cross-sectional study of 38 patients who were treated with GKS for brain tumors, including metastatic and benign brain tumors. All of the patients underwent GKS, and blood samples were collected before and after GKS. NKA was measured using an enzyme-linked immunosorbent assay kit, to measure interferon-gamma (IFNγ) secreted by ex vivo-stimulated NK cells from whole blood. We explored the correlations between NK cell-produced IFNγ (NKA-IFNγ) levels and clinical parameters of patients who were treated with GKS for brain tumors.Results : NKA-IFNγ levels were decreased in metastatic brain tumor patients compared to those with benign brain tumors (p

Thanks to new generation devices, mechanical thrombectomy (MT) has substantially evolved and become the standard treatment for patients with acute occlusion of the internal carotid artery or proximal middle cerebral artery (MCA) (M1 segment). However, the role and benefit of MT in patients with distal MCA (M2 segment) occlusion remain unclear. Therefore, there is a need for further studies. To evaluate the efficacy and safety of MT for M2 occlusion, this article reviews the natural course of M2 occlusion, the evidence regarding MT for M2 segment occlusion, clinical outcomes of MT for M2 occlusion, and treatment outcomes according to device type.

We demonstrate black conductive ink (BCI) that is writable and paintable on traditional handmade Korean paper (Hanji) for application as a high performing electrode. By optimal mixing of Ag nanowire (Ag NW) suspension and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) solution in standard charcoal-based blank ink, we synthesized BCI suitable for writing and painting on Hanji with a normal paintbrush. Due to the shear stress induced by the paintbrush bristles, the Ag NW and PEDOT:PSS mixture was uniformly coated on the porous cellulose structure of Hanji and showed a low sheet resistance of 11.7 Ohm per square even after repeated brush strokes. Moreover, the brush-painted electrodes on Hanji showed a constant resistance during tests of inner/outer bending and folding due to the outstanding flexibility of the Ag NW and PEDOT:PSS mixture that filled the porous cellulose structure of Hanji. Therefore, the pictures drawn in the BCI on Hanji exhibited a level of flexibility and conductivity sufficiently high to enable the BCI to function as an effective electrode even when the paper substrate is wrinkled or crumpled. The successful operation of the paintable interconnector and heater on Hanji indicates the high potential of the brush-painted electrodes that can be used in various social and cultural fields, including fine art, fashion, interior design, architecture, and heating industry.

Objective Carotid endarterectomy (CEA) is an effective surgical procedure for treating symptomatic or asymptomatic patients with carotid stenosis. Many neurosurgeons use a shunt to reduce perioperative ischemic complications. However, the use of shunting is still controversial, and the shunt procedure can cause several complications. In our institution, we used two types of modified arteriotomy suture techniques instead of using a shunt. Methods In technique 1, to prevent ischemic complications, we sutured a third of the arteriotomy site from both ends after removing the plaque. Afterward, the unsutured middle third was isolated from the arterial lumen by placing a curved Satinsky clamp. And then, we opened all the clamped carotid arteries before finishing the suture. In technique 2, we sutured the arteriotomy site at the common carotid artery (CCA). We then placed a curved Satinsky clamp crossing from the sutured site to the carotid bifurcation, isolating the unsutured site at the internal carotid artery (ICA). After placing the Satinsky clamp, the CCA and external carotid artery (ECA) were opened to allow blood flow from CCA to ECA. By opening the ECA, ECA collateral flow via ECA-ICA anastomoses could help to reduce cerebral ischemia. Results The modified suture methods can reduce the cerebral ischemia directly (technique 1) or via using collaterals (technique 2). The modified arteriotomy suture techniques are simple, safe, and applicable to almost all cases of CEA. Conclusion Two modified arteriotomy suture techniques could reduce perioperative ischemic complications by reducing the cerebral ischemic time.

Tsunamis can destroy bridges in coastal areas. Studies have attempted to unravel the mechanism of tsunami-induced damage and develop effective countermeasures against future tsunamis. However, the mechanisms of tsunami-induced erosion of bridge-abutment backfill and its countermeasures have not been studied adequately. This study investigates this topic using numerical analysis. The results show that the tsunami flowing down along the downstream wing of the abutment induces bedload sediment transport on the ogive section of the backfill on the downstream side of the abutment, resulting in the onset of backfill erosion. Sediment suspension and bedload sediment transportation occur when the backfill inside the abutment starts to flow out from below the downstream wing. This leads to subsidence of the backfill at the upstream side of the downstream wing. The subsequent backfill erosion is mainly caused by bedload sediment transport. Numerical experiments on countermeasures show that extending the wings downward can prevent the acceleration of backfill erosion in the presence of the abutment. A combination of multiple countermeasures, including extended wings, would be more effective in maintaining the stability of the abutment after a tsunami. This suggests the application of such countermeasures to actual bridges as an effective countermeasure against backfill erosion.

Nonsaccular vertebral artery aneurysms involving the posterior inferior cerebellar artery (PICA) are rare. Treatment is considered a significant challenge because of their angiographic and anatomical features, especially in high-riding PICA. Therefore, meticulous preoperative angiographic and anatomical evaluation is necessary. Moreover, consideration of the distance between the cerebellar skull base and caudal loop of the PICA is important. We present two cases of occipital artery-high-riding PICA bypass and discuss important preoperative technical considerations.

This paper proposes a hierarchical routing algorithm for enhancing survivability of sensor nodes on WSAN. Proposed algorithm has two important parts. The first is a clustering algorithm that uses distance between sensor and actor, and remaining energy of sensor nodes for selecting cluster head. It will induce uniform energy consumption, and this has a beneficial effect on network lifetime. The second is an enhanced routing algorithm that uses the shortest path tree. The energy efficient routing is very important in WSAN which has energy limitation. As a result, proposed algorithm extends network and nodes lifetime through consuming energy efficiently. Simulation results show that the proposed clustering algorithm outperforms conventional routing algorithms such as VDSPT in terms of node and network life time, delay, fairness, and data transmission ratio to BS.

Rationale: Patients with long term bed rest in intensive care unit after neurosurgery could experience splanchnic hypoperfusion. These patients have several other medical conditions that exacerbate splanchnic hypoperfusion during treatment and the splanchnic hypoperfusion could result in “stress-induced intestinal necrosis”, which could cause massive hematochezia. We report here the experience of life-threatening hematochezia in 3 patients who underwent brain surgery in our institution. Patients concerns: One female patient (72-year-old) and 2 male patients (58- and 35-year-old) were admitted to our institution because of traumatic intracerebral hemorrhage, subarachnoid hemorrhage due to a ruptured anterior communicating artery, and subarachnoid hemorrhage with unknown cause respectively. All patients underwent emergency brain surgery for diagnosis and treatment. After surgery, they all experienced long-term bed rest in intensive care unit. Hematochezia occurred on postoperative day 15, 17, and 49, respectively. Diagnoses: All of the patients were assessed by abdomen/pelvis computed tomography and underwent a colonoscopy. Interventions: The female patient underwent embolization through pelvic arteriography and epinephrine injection through colonoscopy, but a total colectomy and ileostomy was performed due to refractory hematochezia. 58-year-old male patient had a laparoscopic ileostomy for the bowel rest. The other patient underwent nil per os and conservative treatment for 2 weeks. Outcomes: The female patient was discharged without further treatment plan, 58-year-old male patient survived after laparoscopic ileostomy, while the other patient survived after 2 weeks of nil per os. Lesson: Abdominal symptoms, such as hematochezia, should be actively managed in neurosurgical patients who are undergoing long-term bed rest in an intensive care unit under physiologically stressful medical conditions.

Background The unilateral interhemispheric approach for distal anterior cerebral artery aneurysms presents several risks, such as postoperative venous infarction due to occasional sacrifice of parasagittal bridging vein and postoperative frontal lobe damage due to retraction force. To overcome these risks, we used a bifrontal craniotomy with straight dural incision and cutting of the superior sagittal sinus. Methods We retrospectively reviewed 61 patients (42 unruptured and 19 ruptured A2 and A3 aneurysms) who under aneurysm clipping through bifrontal interhemispheric approach between March 2007 and December 2017. There were 35 A2 aneurysms and 27 A3 aneurysms, and mean size of aneurysms was 5.45 mm. The modified bifrontal interhemispheric approach involved 3 steps: bifrontal craniotomy of centrobasal portion of the frontal bone, ligation and division of anterior one third of the superior sagittal sinus, and approaching the aneurysm via the interhemispheric space. All patients underwent computed tomography on postoperative days 3 and 7 for evaluation of brain retraction damage or venous infarction. Results Among patients with ruptured aneurysms, 79% had a favorable outcome (Glasgow Outcome Scale score 4 or 5) 6 months after primary subarachnoid hemorrhage; all patients with unruptured aneurysms had favorable outcomes. Surgical outcome was strongly related to preoperative neurologic Hunt and Hess grade. Three patients had poor outcomes due to poor Hunt and Hess grade on admission (grade 3 in 2 patients, grade 4 in 1 patient). Follow-up CT showed that venous infarction did not occur in any of the patients. Conclusions Modified bifrontal interhemispheric approach may be a safe and effective method for treating A2 and A3 aneurysms with relatively good clinical outcome and no surgery-related complications.

Highly moisture permeation resistive and transparent single layer thin films for the encapsulation of hydrogenated silicon oxynitrides (H:SiON) were deposited by plasma-enhanced chemical vapor deposition (PECVD) using silane (SiH4), nitrous oxide (N2O), ammonia (NH3), and hydrogen (H2) at 100 °C for applications to a top-emission organic light-emitting diode (TEOLED). Addition of H2 into the PECVD process of SiON film deposition afforded the hydrogenated SiON film, which showed not only improved optical properties such as transmittance and reflectance but also better barrier property to water permeation than PECVD SiON and even SiNx. The H:SiON film with thickness of only 80 nm exhibited water vapor transmission rate (WVTR) lower than 5 × 10−5 g per m2 per day in the test conditions of 38 °C and 100% humidity, where this WVTR is the measurement limit of the MOCON equipment. An additional coating of UV curable polymer enabled the H:SiON films to be flexible and to have very stable barrier property lower than 5 × 10−5 g per m2 per day even after a number of 10k times bending tests at a curvature radius of 1R. The mild H:SiON film process improved the electrical properties of top-emission OLEDs without generating any dark spots. Furthermore, single H:SiON films having high water vapor barrier could maintain the original illumination features of TEOLED longer than 720 hours. These excellent properties of the H:SiON thin films originated from the structural changes of the SiON material by the introduction of hydrogen.

Recently, wireless sensor network(WSN) have been used in various fields to implement ubiquitous computing environment. WSN uses small, low cost and low power sensors in order to collect information from the sensor field. This paper proposes a clustering algorithm for energy efficiency of sensor nodes. The proposed algorithm is based on conventional LEACH, the representative clustering protocol for WSN and it prolongs network and nodes life time using sleep technique and changable transmission mode. The nodes of the proposed algorithm first calculate their clustering participation value based on the distance to the neighbor nodes. The nodes located in high density area will have clustering participation value and it ∙제1저자 : 김선철 ∙교신저자 : 조용환 ∙투고일 : 2014. 12. 19, 심사일 : 2015. 1. 13, 게재확정일 : 2015. 3. 25. * 충북대학교 컴퓨터공학과(Dept. of Computer Engineering, Chungbuk National University) ※ 이 논문은 2013년도 충북대학교 학술연구지원사업의 연구비 지원에 의하여 연구되었음 (This paper was supported by the research grant of the Chungbuk National University in 2013) 78 Journal of The Korea Society of Computer and Information April 2015 can turn to sleep mode. Besides, proposed algorithm can change transmission method from conventional single-hop transmission to multi-hop transmission according to the energy level of cluster head. Simulation results show that the proposed clustering algorithm outperforms conventional LEACH, especially non-uniformly deployed network. ▸

Recently, wireless sensor networks(WSNs) are widely used for intrusion detection and ecology, environment, atmosphere, industry, traffic, fire monitoring. In this paper, an energy efficient clustering algorithm is proposed. The proposed algorithm forms clusters uniformly by selecting cluster head that optimally located based on receiving power. Besides, proposed algorithm can induce uniform energy consumption regardless of location of nodes by multi-hop transmission and MST formation with limited maximum depth. Through the above, proposed algorithm elongates ∙제1저자 : 나성원 ∙교신저자 : 조용환 ∙투고일 : 2014. 4. 16, 심사일 : 2014. 4. 25, 게재확정일 : 2014. 5. 21. * 충북대학교 컴퓨터공학과(Dept. of Computer Engineering, Chungbuk National University) ※ 이 논문은 2012년도 충북대학교 학술연구지원사업의 연구비 지원에 의하여 연구되었음 (This paper was supported by the research grant of the Chungbuk National University in 2012) 50 Journal of The Korea Society of Computer and Information June 2014 network life time, reduces energy consumption of nodes and induces fair energy consumption compared to conventional LEACH and HEED. The results of simulation show that the proposed clustering algorithm elongates network life time through fair energy consumption. ▸

Schwannomas account for about 8% of intracranial tumors and 90% are vestibular schwannomas. Oculomotor schwannoma without neurofibromatosis is extremely rare. A 41-year-old female presented with complaints of blurred vision, and the neurologic examination revealed afferent pupillary defect and decreased visual acuity of the left side. Brain magnetic resonance image showed an extra axial mass in the left superior orbital fissure. The patient underwent major surgery via the fronto-temporal approach. The tumor originated from the oculomotor nerve and was subtotally removed under microscopic surgery. The pathological findings confirmed the tumor as a schwannoma. After surgery, ptosis and medial gaze limitation of the left eye was detected, but the symptoms improved gradually.