• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.3 no.1
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• pp.17-29
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• 1999

The reliable authentication of a communicating party and a network component is an essential factor to achieve the security in a computer network. The Kerberos Authentication Services has been the most successful solution which is widely used today but its requirement for synchronized clocks has been a serious limitation to use it. In this paper we presented an extended Kerberos method which avoids the synchronization requirement for a single-time ticket user. We modified the Kerberos protocol minimally by replacing the synchronization requirement with the challenge-response method.

• Journal of Korean Neurosurgical Society
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• v.38 no.2
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• pp.89-95
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• 2005

Objective : The purpose of this study is to analyze aneurysm morphology and define limitations and feasibility in endovascular Gugliemi detachable coil[GDC] embolization for anterior communicating artery [ACoA] aneurysms. Methods : From January 2000 through October 2003, 123patients were treated with endovascular coil embolization for ACoA aneurysms. There were 75women and 48men, with a mean age of 63years. All ruptured aneurysms were treated within 15days of rupture. Aneurysm morphology was classified according to neck size and projection of aneurysm dome as follows-A : neck of aneurysm <4mm & anterior projection, B : neck of aneurysm [4mm & anterior projection, C : neck of aneurysm<4mm & posterior [superior] projection, D : neck of aneurysm [4mm & posterior [superior] projection, E : neck of aneurysm<4mm & inferior projection, and F : neck of aneurysm [4mm & inferior projection. Endovascular procedures were categorized as either "successful" or "unsuccessful". Clinical follow-up was estimated at discharge and at 6months, post treatment results were classified according to Glasgow Outcome Scale[GOS]. Results : Successful embolization for ACoA was performed in 86patients of 123patients [69.9%]. Complete or near complete aneurysm occlusion was observed in 102patients [82.9%]; a neck remnant was observed in 6patients [4.9%]; partial embolization was done in 3patients [2.4%]; and embolization was attempted in 12patients [9.8%]. Among 55patients with follow-up angiographic results, 18patients [32.7%] were defined as recanalization of the aneurysm sac. Morphological analysis demonstrated that anterior projecting aneurysms and morphological classifications [morphological classifications worsens [A - D] chances of successful coil occlusion significantly decrease] were major factors in successful embolization, and, inferiorly projecting and wide neck [${\ge}4mm$] aneurysms are highly related to recanalization of aneurysms. Conclusion : Endovascular coil embolization of ACoA aneurysms shows good outcome in our study. Nevertheless, there is a limitation in the endovascular approach to ACoA, even though advanced modern techniques evolve rapidly. Compensatory surgical approach with the endovascular approach is required for successful treatment of ACoA aneurysms.

• Journal of Korean Neurosurgical Society
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• v.30 no.6
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• pp.711-716
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• 2001

Objectives : Three-dimensional computed tomographic angiography(3D-CTA) is recently developed diagnostic imaging modality. We have studied this noninvasive method for possible role in replacing conventional angiography( CA) in the detection of aneurysms of the circle of Willis in patients with subarachnoid hemorrahge(SAH). Methods : We studied retrospectively, the 100 patients with SAH or unruptured aneurysms admitted to our hospital from October 1997 to December 1998. Among there, 85 patients underwent CTA, 82 patients underwent CA and 67 patients underwent both of CTA and CA. 3D-CTA was obtained using maximum intensity projection(MIP) and shaded-surface display(SSD) reconstruction. Results : Total 107 aneurysms were detected in 92 patients, and 64 aneurysms were detected in 67 patients underwent both CTA and CA. In five cases of those 67 cases, aneurysms were detected by CA but not by 3D-CTA. The detection rate of aneurysms(91.8%) and the detection rate of parent artery in cases of anterior communicating artery aneurysms(86.9%) with total 3D-CTA were relatively compatible with that of CA. But 3D-CTA was not enough in detection of posterior communicating artery aneurysms, internal carotid artery aneurysms as well as small sized aneurysm(<3mm). Conclusion : We consider CTA is valuable in as a screening test for cerebral aneurysm and follow-up test. And it is also valuable in early surgery for patients with aneurysmal rebleeding because of simple, quick, non-invasive method.

• Journal of Korean Neurosurgical Society
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• v.38 no.1
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• pp.28-34
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• 2005

Objective : This study is performed to compare older with younger groups about clinical characteristics and overall outcome of treatments for the intracranial aneurysms. Methods : We retrospectively investigated 633 patients with cerebral aneurysms who were admitted to our institute from January 2000 to May 2004. The authors divided the patients of cerebral aneurysm into two groups, one the third, fourth decades and the other eighth, ninth decades, analyzed clinical characteristics and overall outcome of treatments. Results : There were 57 patients [9.0%] under 39years old and 58 patients [9.2%] over 70. The female to male sex ratio was 0.5 : 1 in the younger group[YG] and 7.3 : 1 in the older group[OG], showing a female predominance with increasing age. In the YG, aneurysms were found in anterior communicating artery[A-com] [44.8%], middle cerebral artery [31.0%]. In the OG, aneurysm of posterior communicating artery [30.1%] was most common followed by that of A-com [26.9%]. More smokers and alcoholics were found in the YG. Older age was related to poor Hunt-Hess grade, Fisher's grade on admission, high incidence of unruptured aneurysms, and endovascular surgery. There was a higher prevalence of hypertension, intraventricular hematoma, hydrocephalus, and rebleeding in the preoperative state in the OG and postoperative complications including hydrocephalus, subdural fluid collection, and systemic complications. Overall outcome was poorer with advancing age [p=0.01]. Conclusion : The patients with aneurysms in the YG have distinct characteristics compared to those in the OG. Because of a good clinical grade on admission, a thin subarachnoid clot, and Low incidence of perioperative complications, the overall outcomes of the young patients were better than those of the old patients.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.215-223
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• 2022

Objective : This retrospective study investigated the clinical and angiographic characteristics of ruptured true posterior communicating artery (PCoA) aneurysms in comparison with junctional PCoA aneurysms presenting with a subarachnoid hemorrhage. Methods : The medical records and radiological data of 93 consecutive patients who underwent three-dimensional rotational angiography and surgical or endovascular treatment for a ruptured junctional or true PCoA aneurysm over an 8-year period were examined. Results : The maximum diameter of the ruptured true PCoA aneurysm (n=13, 14.0%) was significantly smaller than that of the ruptured junctional PCoA aneurysms (n=80, 4.45±1.44 vs. 7.68±3.36 mm, p=0.001). In particular, the incidence of very small aneurysms <4 mm was 46.2% (six of 13 patients) in the ruptured true PCoA aneurysm group, yet only 2.5% (two of 80 patients) in the ruptured junctional PCoA aneurysm group. Meanwhile, the diameter of the PCoA was significantly larger in the true PCoA aneurysm group than that in the junctional PCoA aneurysm group (1.90±0.57 vs. 1.15±0.49 mm, p<0.001). In addition, the ipsilateral PCoA/P1 ratio was significantly larger in the true PCoA aneurysm group than that in the group of a junctional PCoA aneurysm (mean PCoA/P1 ratio±standard deviation, 2.67±1.22 vs. 1.14±0.88; p<0.001). No between-group difference was identified for the modified Fisher grade, clinical grade at admission, and 3-month modified Rankin Scale score. Conclusion : A true PCoA aneurysm was found to be associated with a larger PCoA and ruptured at a smaller diameter than a junctional PCoA aneurysm. In particular, the incidence of a ruptured aneurysm with a very small diameter <4 mm was significantly higher among the patients with a true PCoA aneurysm.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.531-538
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• 2022

Objective : Anterior communicating artery (Acom) aneurysm is one of the most common intracranial aneurysms, constituting approximately 30-35% of all aneurysm formation in the brain. Anatomically, the H-complex (the anatomic morphology of both A1 to A2 segments) is thought to affects the nature of the Acom aneurysm due to its close relationship with the hemodynamics of the vessel. Therefore, we investigated the relative risk factors of aneurysmal rupture, especially focusing on H-complex morphology of the Acom. Methods : From January 2016 to December 2020, a total of 209 patients who underwent surgery, including clipping and coiling for Acom aneurysm in our institution were reviewed. There were 102 cases of ruptured aneurysm and 107 cases of unruptured aneurysm. The baseline morphology of aneurysms was investigated and the relationship between the H-complex and the clinical characteristics of patients with Acom aneurysms was assessed. Results : Of the 209 patients, 109 patients (52.1%) had symmetrical A1, 79 patients (37.8%) had unilateral hypoplastic A1, and 21 patients (10.0%) had aplastic A1. The hypoplastic A1 group and the aplastic A1 group were grouped together as unilateral dominancy of A1, and were compared with the symmetrical A1 group. There was no significant difference in demographic characteristics and radiological findings of Acom aneurysms between two groups. However, when dichotomizing the patients into ruptured cases and unruptured cases, unilateral dominance of the A1 segment was associated with aneurysmal rupture with statistical significance (p=0.011). Conclusion : These results suggest that the unilateral dominance of the A1 segment does not have a significant effect on the morphology of Acom aneurysms, but contributes to aneurysmal rupture. Thus, we can better understand the effects of hemodynamics on Acom aneurysm.

• Journal of Korean Neurosurgical Society
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• v.40 no.4
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• pp.239-244
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• 2006

Objective : The present study evaluated overall surgical results for 3,000 patients with intracranial aneurysms, operated on in Busan Paik Hospital institution. Methods : Three thousand aneurysm cases, operated on in Busan Paik Hospital between January 1980 to June, 15th, 2005, were evaluated based on the following criteria; aneurysm form, aneurysm location, surgical results, postoperative complications, and seasonsonality of occuence. 957 cases were anterior communicating artery aneurysms, 776 were internal carotid artery[ICA] aneurysms, 755 were middle cerebral artery[MCA] aneurysms, 96 were anterior cerebral artery[ACA] aneurysms, 128 were vertebro-basilar artery[VBA] aneurysms and 288 were multiple aneurysms. The male to female ratio was 0.7 to 1 Surgical methods included 2.738 clippings, 219 coating and wrappings, 23 aneurysmoraphies, 20 proximal ligations. Results : Rebleeding occured in 5.1% of the early operation group and 16% of the late operation group respectively. Incidence of clinical vasospasm was 166% and angiographic vasospasm was 24.1%. The percentage of the multiple aneurysms was 9.5%, the percentage of the dissecting aneurysm was 6 cases [0.2%], 6 of the total [0.2%];De Novo" aneurysm, the percentage of lobectomies with clipping cases was 9 cases [03%] the percentage were incidental aneurysms; 164 [5.5%]. 88.1% had overall favorable surgical results with a 5.5 % mortality rate. Calcium-channel blocker and "Triple H" therapy did not improve mortality but did significantly improve morbidity. In the old age group, early operation reduced vasospasm, rebleeding and medical complications. The early surgery group exhibited a 86.2% favorable outcome with a 8.1% mortality rate. Intraoperative angiography reduced residual or remained aneurysms in large, giant aneurysm, especially in A.com artery aneurysm. Conclusion : The surgical results for the early surgery group according to surgical timming was better, but there were not statistically significant. ntraoperative angiography was especially useful on large aneurysms of the anterior communicating artery.

• Journal of Korean Neurosurgical Society
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• v.40 no.4
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• pp.227-233
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• 2006

Objective : To determine the rationale for treating pure unruptured intracranial aneurysms[UIAs]. it is mandatory to know the risk of each treatment modality. The purpose of this study is to evaluate the surgical risk for treating UIAs. Methods : Between December 1994 and May 2005, 147 unruptured aneurysms in 135 patients were treated. The majority of these cases [94.6%] were treated with aneurysmal neck clipping. The remainder received aneurysmal wrapping [2.7%], trapping with bypass [20%], or proximal occlusion [0.7%]. The clinical outcomes were evaluated in each patient by the Glasgow Outcome Scale at one month post-surgery. Results : The patient pool consisted of 41 males and 94 females. The mean age was 55.9 years [range : $16{\sim}82$]. The aneurysms were located at middle cerebral artery in 63 [42.9%]. anterior communicating artery 30 [20.4%], posterior communicating artery in 26 [177%]. internal carotid artery[ICA] in 14 [95%], anterior choroidal artery in 4 [2.7%] and others in 10[6.9%]. One hundred fifteen [78.2%] of aneurysms were small [<10mm]. Others were large [10 to 25mm] and giant [>25mm]; 29 [19.7%] and 3 [21%] respectively. More than ninety percent [91.1%] of all patients recovered well. Mild to severe disability was seen in 8.7% of the patients. One patient succumbed to complications following injury to the ICA. Conclusion : The mortality and morbidity associated with UIA surgery at our hospital compared very favorably to the previous reported literature and with the previously established natural history of this disease.

• Journal of Chest Surgery
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• v.47 no.2
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• pp.152-154
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• 2014

Vieussens' arterial ring (VAR) is the connection between the conus branch of the right coronary artery and the proximal right ventricular branch of the left anterior descending coronary artery. VARs are found in 48% of the population; however, pathologic VAR is rare. We experienced a case of pathologic VAR that involved a fistula connecting to the main pulmonary artery.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.596-598
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• 1999

본 논문은 UML-RT 도구로서 GCSR(Graphical Communicating Shared Resource)를 제안하는데 있어UML의 기본 다이아그램 중 하나인 Statechart와 비교 분석함으로 그 기능과 장.단점을 제시한다. 기존의 정형 명세 언어인 Statechart에서는 실시간 시스템이 명세에 있어 필수적인 시간적인 개념과 우선순위 개념이 제한적이다. 그러나 정형명세의 또 다른 언어인 GCSR이 가진 시간적 개념과 우선순위 개념의 효용을 보이고 이를 Statechart의 실시간 시스템의 명세와 비교함으로 UML-RT로서의 GCSR을 제안한다.