• Korean Journal of Radiology
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• v.21 no.12
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• pp.1334-1344
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• 2020

Objective: Compressed sensing (CS) has gained wide interest since it accelerates MRI acquisition. We aimed to compare the 3D post-contrast T1-weighted volumetric isotropic turbo spin echo acquisition (VISTA) with CS (VISTA-CS) and without CS (VISTA-nonCS) in intracranial vessel wall MRIs (VW-MRI). Materials and Methods: From April 2017 to July 2018, 72 patients who underwent VW-MRI, including both VISTA-CS and VISTA-nonCS, were retrospectively enrolled. Wall and lumen volumes, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured from normal and lesion sites. Two neuroradiologists independently evaluated overall image quality and degree of normal and lesion wall delineation with a four-point scale (scores ≥ 3 defined as acceptable). Results: Scan coverage was increased in VISTA-CS to cover both anterior and posterior circulations with a slightly shorter scan time compared to VISTA-nonCS (approximately 7 minutes vs. 8 minutes). Wall and lumen volumes were not significantly different with VISTA-CS or VISTA-nonCS (interclass correlation coefficient = 0.964-0.997). SNR was or trended towards significantly higher values in VISTA-CS than in VISTA-nonCS. At normal sites, CNR was not significantly different between two sequences (p = 0.907), whereas VISTA-CS provided lower CNR in lesion sites compared with VISTA-nonCS (p = 0.003). Subjective wall delineation was superior with VISTA-nonCS than with VISTA-CS (p = 0.019), although overall image quality did not differ (p = 0.297). The proportions of images with acceptable quality were not significantly different between VISTA-CS (83.3-97.8%) and VISTA-nonCS (75-100%). Conclusion: CS may be useful for intracranial VW-MRI as it allows for larger scan coverage with slightly shorter scan time without compromising image quality.

• The KIPS Transactions:PartC
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• v.15C no.3
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• pp.141-148
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• 2008

Windows Vista published by Microsoft provides more powerful security mechanisms than previous Windows operating systems. In the forensics point of view, new security mechanisms make it more difficult to get data related to the criminals in a storage device. In this paper, we analyze BitLocker introduced as an new security mechanism in Windows Vista. Also, compared to the previous Windows operating systems, the changes and security issues of UAC and EFS in Windows Vista are discussed in the forensics point of view. Futhermore, we discuss other characteristics of Windows Vista useful for forensic examinations.

• Investigative Magnetic Resonance Imaging
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• v.17 no.2
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• pp.110-122
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• 2013

Purpose : To compare the image quality and ligament traceability in ankle images obtained using Volume Isotropic Turbo Spin Echo Acquisition (VISTA) MRI with and without fat suppression. Materials and Methods: The signal-to-noise ratios (SNRs) in images from a phantom and from the ankle of a volunteer were compared. Ten ankles from 10 non-symptomatic volunteers were imaged for comparisons of contrast ratio (CR) and ligament traceability. All examinations were performed using VISTA sequences with and without fat suppression on a 3T MRI scanner. The SNRs were obtained from images with subjects and without subjects (noise-only). Contrast ratios from images of the 10 ankles were acquired between fluid and tendon (F-T), F-cartilage (C), F-ligament (L), fat (f)-T, f-C and f-L. Two musculoskeletal radiologists independently scored the traceability of 7 ligaments, in sagittal, axial and coronal images respectively, based on a 4-point scale (1 as not traceable through 4 as clearly traceable). The Wilcoxon signed-rank test was used to compare the CR. Fisher's exact test and Pearson's chi-squared test were used to compare the ligament traceability. Results: The SNRs did not differ significantly between the two sequences except in bone marrow. VISTA SPAIR showed the higher CR only in F-T (p = 0.04), whereas VISTA showed higher CR in f-T (p = 0.005), f-C (p = 0.005) and f-L (p = 0.005). The calcaneofibular ligament traceability with VISTA was superior to that obtained with VISTA SPAIR (p < 0.05) in all planes. Conclusion: VISTA showed significant superiority to VISTA SPAIR in tracing CFL due to the superior CR between fat and ligament.

• Review of KIISC
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• v.17 no.2
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• pp.57-65
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• 2007

게임 산업에서 Vista 출시가 의미하는 보안 환경의 변화와 위험요소에 대해 설명을 하고 어떤 위험이 존재하고 있는지 인지하는 것이 필요하다. 현재의 게임 산업이 처한 보안상의 위험요소들을 먼저 확인을 하며 Vista로 인해 달라지는 보안상의 위험요소에 대해 명시하도록 한다. Vista에서 강화된 보안기능으로는 ActiveX의 실행제한과 UAC(User Access Control) 기능을 들 수 있는데 온라인 게임에 미치는 영향과 보안상의 이슈에 대해서 관계를 확인하여 보고 향후 방향에 대해 조망한다.

• Restorative Dentistry and Endodontics
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• v.47 no.4
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• pp.44.1-44.1
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• 2022

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.2
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• pp.114-123
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• 2002

Called VISTA (Variable-stability In-flight Simulator Test Aircraft), the one-of-a-kind NF-l6D has a simulation system that can mimic several aircraft. Though housed in an F-l6 Fighting Falcon airframe, VISTA can also act like the F-15 Eagle or the Navy's F-14 Tomcat. More importantly, such flexibility allows for improved training and consolidation of some sorties. Consequently USAF Test Pilot School students will have an opportunity to learn how to test future integrated cockpits. In this paper we will use the multiple model adaptive estimation (MMAE) and the multiple model adaptive controller (MMAC) techniques to model the aircraft's flight control system containing the longitudinal and lateral-directional axes. Single and dual actuator and sensor failures will also be included in the simulation. White Gaussian noise will be included to simulate the effects of atmospheric disturbances.

• Journal of the Korean Society for Library and Information Science
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• v.31 no.2
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• pp.177-197
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• 1997

The study measured whether two search engines retrieve different Web documents for 6 queries. Two different search engines, Alta Vista in terms of keyword search engines and Yahoo in terms of subject directory engines were measured using as criteria, total number of documents retrieved, total number of relevant documents retrieved, recall and precision ratios. In addition, Alta Vista was suitable for specific and technical terms, while Yahoo was effective for general and plain terms. However, more elaborate research needs to be tested in terms of query characteristics.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1115-1118
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• 2007

BitLocker는 2006년에 Microsoft가 새롭게 출시한 운영체제인 Windows Vista에서 처음 사용되는 보안 메커니즘이다. 기존의 다양한 운영체제에서 사용되는 보안 메커니즘은 기본적으로 사용자가 로그인한 후 로그인한 사용자의 데이터를 바탕으로 파일에 대한 암호화, 데이터에 접근에 관한 권한 확인과 같은 방법을 사용하여 데이터를 보호했다. 하지만 이러한 보안 메커니즘은 물리적으로 접근하는 공격방법에는 취약하고, 플랫폼 자체에 대한 신뢰성이 부족하기 때문에 새롭게 Microsoft에서 새롭게 제안하는 보안 메커니즘인 BitLocker는 디스크 자체를 암호화 해서 보호하는 새로운 메커니즘이다. 본 논문에서는 Windows Vista에서 사용되는 새로운 보안 메커니즘인 BitLocker의 운영 메커니즘에 대해서 분석하고 이를 바탕으로 Windows 보안 메커니즘에 대한 취약점을 검증하기 위한 기존 자료로 활용하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.10a
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• pp.82.2-82.2
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• 2003

• Journal of the Korea Computer Graphics Society
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• v.6 no.1
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• pp.29-36
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• 2000

In this work, we propose ZF-buffer algorithm in order to accelerate the intersection test of ray-tracing algorithm. ZF-buffer is used in the preprocessing of ray-tracing and records the pointer that points to a parent face of a depth value(z value) of an object determined in Z-buffer. As a result, the face which intersects with the first ray can be determined easily by using the pointer stored in F-buffer. Though ZF-buffer and vista-buffer resemble each other, the difference between the two methods is that what ZF-buffer records is not bounding volume but the pointer of a displayable face. We applied the ZF-buffer algorithm for the first ray to Utah teapot which consists of 9216 polygons. By comparing the elapse time of our method with vista-buffer algorithm, we can acquire improvement in speed that it is 3 times faster than vista-buffer algorithm. We expanded our algorithm to the second ray.