• Journal of Korean Neurosurgical Society
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• v.43 no.6
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• pp.275-280
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• 2008

Objective : In order to assess the incidence of thromboembolic events and their clinical presentations, the present study prospectively examined routine brain magnetic resonance images (MRI) taken within 48 hours after a coil embolization of cerebral aneurysms. Methods : From January 2006 to January 2008, 163 cases of coil embolization of cerebral aneurysm were performed along with routine brain MRI, including diffusion-weighted magnetic resonance (DW-MR) imaging, within 48 hours after the embolization of the aneurysm to detect the silent thromboembolic events regardless of any neurological changes. If any neurological changes were observed, an immediate brain MRI follow-up was performed. High-signal-intensity lesions in the DW-MR images were considered as acute thromboembolic events and the number and locations of the lesions were also recorded. Results : Among the 163 coil embolization cases, 98(60.1%) showed high-signal intensities in the DW-MR imaging follow-up, 66 cases (67.0%) involved the eloquent area and only 6cases (6.0%) showed focal neurological symptoms correlated to the DW-MR findings. The incidence of DW-MR lesions was higher in older patients (${\geq}60$ yrs) when compared to younger patients (<60 yrs) (p=0.002, odd's ratio=1.043). The older patients also showed a higher incidence of abnormal DW-MR signals in aneurysm-unrelated lesions (p=0.0003, odd's ratio=5.078). Conclusion : The incidence of symptomatic thromboembolic attacks after coil embolization of the cerebral aneurysm was found to be lower than that reported in previous studies. While DW-MR imaging revealed a higher number of thromboembolic events, most of these were clinically silent and transient and showed favorable clinical outcomes. However, the incidence of DW-MR abnormalities was higher in older patients, along with unpredictable thromboembolic events on DW-MR images. Thus, in order to provide adequate and timely treatment and to minimize neurological sequelae, a routine DW-MR follow-up after coil embolization of cerebral aneurysms might be helpful, especially in older patients.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.2
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• pp.159-178
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• 2013

We present a model, combining servitization decision and a conventional two-sided market approaches, to understand expected outcomes and current market situations. We suppose an individual manufacturer participates in multiple platforms and decides whether to initiate servitization by considering latent profitability and risk. The analytical results from the model show that increasing competition within servitized companies lead to a servitization equilibrium, wherein the ratio of servitized companies in a market is stable, due to a gradual decline in relative benefits compared to non-servitized companies. This holds even in the case that the number of customer is increasing along the diffusion of servitization, under some restricted conditions.

• Journal of Public Diplomacy
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• v.1 no.1
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• pp.5-35
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• 2021

Where government communication in the early 20^th century fell under the umbrella term, "propaganda," the post-WWII era saw a paradigm fracture into public affairs for domestic audiences, public diplomacy for foreign audiences, and psychological operations for hostile audiences. The continued diffusion of the Internet, however, has blurred such distinctions, mending this fractured paradigm. Based on in-depth interviews, this study typologizes government communication to contextualize how various tactics functions within the 21^st century digital media ecology, through an "Information Intervention" taxonomy. In an age where state-sponsored disinformation and computational propaganda are tantamount threats, this paper elucidates the field's fundamental concepts by articulating who communicates with what audience, in what manner, with what intent, and with what desired outcomes.

• Journal of Korean Neurosurgical Society
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• v.66 no.2
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• pp.144-154
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• 2023

Objective : Stroke caused from large vessel occlusion (LVO) has emerged as the most common stroke subtype worldwide. Intravenous tissue plasminogen activator administration (IV-tPA) and additional intraarterial thrombectomy (IA-Tx) is regarded as standard treatment. In this study, the authors try to find the early recanalization rate of IV-tPA in LVO stroke patients. Methods : Total 300 patients undertook IA-Tx with confirmed anterior circulation LVO, were analyzed retrospectively. Brain computed tomography angiography (CTA) was the initial imaging study and acute stroke magnetic resonance angiography (MRA) followed after finished IV-tPA. Early recanalization rate was evaluated by acute stroke MRA within 2 hours after the IV-tPA. In 167 patients undertook IV-tPA only and 133 non-recanalized patients by IV-tPA, additional IA-Tx tried (IV-tPA + IA-Tx group). And 131 patients, non-recanalized by IV-tPA (IV-tPA group) additional IA-Tx recommend and tried according to the patient condition and compliance. Results : Early recanalization rate of LVO after IV-tPA was 12.0% (36/300). In recanalized patients, favorable outcome (modified Rankin Scale, 0-2) was 69.4% (25/36) while it was 32.1% (42/131, p<0.001) in non-recanalized patients. Among 133 patients, non-recanalized after intravenous recombinant tissue plasminogen activator and undertook additional IA-Tx, the clinical outcome was better than not undertaken additional IA-Tx (favorable outcome was 42.9% vs. 32.1%, p=0.046). Analysis according to the perfusion/diffusion (P/D)-mismatching or not, in patient with IV-tPA with IA-Tx (133 patients), favorable outcome was higher in P/D-mismatching patient (52/104; 50.0%) than P/D-matching patients (5/29; 17.2%; p=0.001). Which treatment tired, P/D-mismatching was favored in clinical outcome (iv-tPA only, p=0.008 and IV-tPA with IA-Tx, p=0.001). Conclusion : The P/D-mismatching influences on the recanalization and clinical outcomes of IV-tPA and IA-Tx. The authors would like to propose that we had better prepare IA-Tx when LVO is diagnosed on initial diagnostic imaging. Furthermore, if the patient shows P/D-mismatching on MRA after IV-tPA, additional IA-Tx improves treatment results and lessen the futile recanalization.

• Journal of Korea Technology Innovation Society
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• v.11 no.4
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• pp.613-638
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• 2008

The Korean government established 'the Act on Performance Evaluation and Management for National Research & Development (R&D) Programs' in 2005, and one year later constructed a master plan, 'A Basic Plan for the Management and Utilization of R&D performance' that focused on better diffusing the public R&D outcomes. In this study we propose a model of performance monitoring, evaluation, and management system for national R&D, which is based on a systematic approach and the logic model that has been prevalently used in planning and evaluating the public programs, to meet the purpose of the law and the master plan as well as to facilitate the diffusion of national R&D outcomes focused mainly on the industrial application technology. Furthermore, in order to use the model for the several applications, the model's specific measures which includes the quantitative methodologies such as analytic hierarchy process (AHP) and data envelopment analysis (DEA) are suggested in accordance with the existing system of the evaluation institution in Korea.

• Journal of Chest Surgery
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• v.56 no.1
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• pp.42-48
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• 2023

Background: With recent advances in cardiac surgery through minimal access, mini-thoracotomy has emerged as an excellent alternative for cardiac myxoma resection. This study analyzed the surgical results of this approach, focusing on postoperative cerebral embolism and tumor recurrence. Methods: We retrospectively reviewed 64 patients (mean age, 56.0±12.1 years; 40 women) who underwent myxoma resection through mini-thoracotomy from October 2008 to July 2020. We conducted femoral cannulation and antegrade cardioplegic arrest in all patients. Patient characteristics and perioperative data, including brain diffusion-weighted magnetic resonance imaging (DWI) findings, were collected. Medium-term echocardiographic follow-up was performed. Results: Thirteen patients (20.3%) had a history of preoperative stroke, and 7 (11.7%) had dyspnea with New York Heart Association functional class III or IV. Sixty-one cases (95.3%) had myxomas in the left atrium. The mean cardiopulmonary bypass and cardiac ischemic times were 69.0±28.6 and 34.1±15.0 minutes, respectively. Sternotomy conversion was not performed in any case, and 50 patients (78.1%) were extubated in the operating room. No early mortality or postoperative clinical stroke occurred. Postoperative DWI was performed in 32 (53%) patients, and 7 (22%) showed silent cerebral embolisms. One patient underwent reoperation for tumor recurrence during the study period; in that patient, a genetic study confirmed the Carney complex. Conclusion: Mini-thoracotomy for cardiac myxoma resection showed acceptable clinical and neurological outcomes. In the medium-term echocardiographic follow-up, reliable resection was proven, with few recurrences. This approach is a promising alternative for cardiac myxoma resection.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.230-237
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• 2020

In this part, an implicit time dependent solution is presented for the Boltzmann transport equation discretized by the analytic coarse mesh finite difference method (ACMFD) over the spatial domain as well as the simplified P₃ (SP₃) for the angular variable. In the first part of this work we proposed a SP₃-ACMFD approach to solve the static eigenvalue equations which provide the initial conditions for temp dependent equations. Having solved the 3D multi-group SP₃-ACMFD static equations, an implicit approach is resorted to ensure stability of time steps. An exponential behavior is assumed in transverse integrated equations to establish a relationship between flux moments and currents. Also, analytic integration is benefited for the time-dependent solution of precursor concentration equations. Finally, a multi-channel one-phase thermal hydraulic model is coupled to the proposed methodology. Transient equations are then solved at each step using the GMRES technique. To show the sufficiency of proposed transient SP₃-ACMFD approximation for a full core analysis, a comparison is made using transport peers as the reference. To further demonstrate superiority, results are compared with a 3D multi-group transient diffusion solver developed as a byproduct of this work. Outcomes confirm that the idea can be considered as an economic interim approach which is superior to the diffusion approximation, and comparable with transport in results.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.110-115
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• 2018

Transient ischemic attack (TIA) indicates high risk for major stroke and is considered a medical emergency. Diffusion-weighted imaging (DWI) enables detection of acute ischemic lesions. The clinical significance of DWI positive lesions in TIA is obscure and its prevalence, clinical features are not established. Therefore, we performed a clinical, etiological and prognostic analysis through a cross-sectional analysis of 235 TIA patients, grouped according to presence of DWI lesion. Clinical features, underlying risk factors for stroke, outcome and rate of recurrence were analyzed. 3 months follow-up of modified Rankin Scales (mRS) were done with telephone survey. DWI positive lesions were present in 14.0% of patients. Etiological factors significantly associated with DWI lesions in TIA patients were male sex (p = 0.038), stroke history (p = 0.012) and atrial fibrillation (p < 0.001). Presence of at least one medium or high risk of cardioembolism from TOAST classification were not associated with lesions when excluding association to atrial fibrillation (p = 0.108). Clinical features showed no significant difference. Whether the patients had lesion-positive DWI was not related to an increase in mRS score during the hospital stay or at the 3-month follow-up after discharge. Future studies should include multi-center samples with large numbers, considering each unique medical environment. Routine acquisition of follow-up DWI for proper evaluation of the tissue-based definition of TIA should also be considered.

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.665-675
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• 2020

Purpose This study aimed to identify independent predictors of favorable outcomes associated with emergent carotid artery stenting (CAS) in patients with acute anterior circulation stroke. Materials and Methods This study included 93 patients with acute stroke who underwent emergent CAS to treat stenoocclusive lesions in the cervical internal carotid artery (ICA) within 6 hours of the onset of the associated symptoms. Data were compared between patients with and without favorable outcomes. The independent predictors of a favorable outcome were determined via logistic regression analysis (modified Rankin Scale 0-2 at 90 days). Results Intracranial tandem occlusion was noted in 81.7% of patients (76/93) among which (76/93), 55 of whom underwent intracranial recanalization therapy. Intracranial reperfusion was successful in 74.2% (69/93) and favorable outcomes were noted in 51.6% of patients (48/93). The mortality rate was 6.5% (6/93). In logistic regression analysis, diffusion-weighted imaging-Alberta Stroke Program Early CT Score [odds ratio (OR), 1.487; 95% confidence interval (CI), 1.018-2.173, p = 0.04], successful reperfusion (OR, 5.199; 95% CI, 1.566-17.265, p = 0.007), and parenchymal hemorrhage (OR, 0.042; 95% CI, 0.003-0.522, p = 0.014) were independently associated with a favorable outcome. Conclusion Baseline infarct size, reperfusion status, and parenchymal hemorrhage were independent predictors of favorable outcomes after emergent CAS to treat stenoocclusive lesions in the cervical ICA in patients with acute anterior circulation stroke.

• Investigative Magnetic Resonance Imaging
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• v.22 no.1
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• pp.56-60
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• 2018

Therapeutic hypothermia in cardiac arrest patients is associated with favorable outcomes mediated via neuroprotective mechanisms. We report a rare case of a 32-year-old male who demonstrated complete recovery of signal changes on perfusion-weighted imaging after therapeutic hypothermia due to cardiac arrest. Brain MRI with perfusion-weighted imaging, performed three days after ending the hypothermia therapy, showed a marked decrease in relative cerebral blood flow (rCBF) and delay in mean transit time (MTT) in the bilateral basal ganglia, thalami, brain stem, cerebellum, occipitoparietal cortex, and frontotemporal cortex. However, no cerebral ischemia was not noted on diffusion-weighted imaging (DWI) or fluid-attenuated inversion recovery (FLAIR) sequences. A follow-up brain MRI after one week showed complete resolution of the perfusion deficit and the patient was discharged without any neurologic sequelae. The mechanism and interpretation of the perfusion changes in cardiac arrest patients treated with therapeutic hypothermia are discussed.