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QoS와 신뢰성을 제공하는 확장성 있는 오버레이 멀티캐스트
이춘성,송정욱,최병욱,한선영,Rhee, Choon-Sung,Song, Jung-Wook,Choi, Byoung-Uk,Han, Sun-Young 한국정보처리학회 2006 정보처리학회논문지 C : 정보통신,정보보안 Vol.13 No.6
본 논문에서는 확장성 있고 신뢰성 있는 오버레이 멀티캐스트를 지원하기 위하여 새로운 멀티캐스트 트리 구성 방법과 지역적인 멀티캐스트를 도입하였다. 본 논문에서 제안하는 구조는 멀티캐스트 네트워크와 멀티캐스트를 지원하지 않는 네트워크가 혼합된 환경에서 멀티캐스트소스로부터 사용자들에게 스트리밍 데이터를 효율적으로 전달할 수 있다 새로운 멀티캐스트 트리 구성 방식은 서브넷에 릴레이가 존재하지 않는 경우에 최적의 조건인 원격 릴레이와 접속을 가능하게 한다. 또한, IPv6 헤더의 Traffic Class에 새로운 서비스 타입을 정의하여 릴레이에서 선택적인 FEC 적용과 차별화 된 전송을 가능하게 하였다. 우리가 제시한 해결책의 효과를 검증하기 위하여, 실제 서비스 환경과 유사한 환경을 시뮬레이터로 구현하고 테스트하였으며, 그 테스트 결과는 전통적인 유니캐스트 접근 방식과 기존의 오버레이 멀티캐스트 방식보다 훨씬 더 효율적인 것으로 판명되었다. In order to support overlay multicast with scalability and reliability, in this paper, we introduced a new multicast tree construction method and a regional multicast. The architecture we introduce efficiently transmits streaming data to the users from multicast source in an environment in which non-multicast network and multicast network. The new multicast tree construction method enables the connection with a remote relay which is an optimum condition in case there is no relay in subnet. Besides, by defining a new service type to traffic class of IPv6 header, a selective adoption or FEC and a distinctive transmission became possible. In order to verify the effect of the solution we suggested, we embodied an environment which is similar to the actual service environment by a simulator and tested it. The result of the test shows that the proposed method is more efficient than the traditional unicast approach method and the existing overlay multicast.
Preoperative Magnetic Resonance Imaging Evaluation in Patients with Adolescent Idiopathic Scoliosis
이춘성,황창주,김남흔,노현민,이미영,윤소정,이동호 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.1
Study Design: Retrospective case series. Purpose: The purpose of this study was to examine the incidence of neural axis abnormalities and the relevant risk factors in patients with adolescent idiopathic scoliosis (AIS). Overview of Literature: The use of preoperative magnetic resonance imaging (MRI) to assess the whole spine in patients with idiopathic scoliosis is controversial, and indications for such MRI evaluations have not been definitively established. However, we routinely use whole-spine MRI in patients with scoliosis who are scheduled to undergo surgical correction. Methods: A total of 378 consecutive patients with presumed AIS who were admitted for spinal surgery were examined for neural axis abnormalities using MRI. To differentiate patients with normal and abnormal MRI findings, the following clinical parameters were evaluated: age, sex, menarcheal status, rotation angle (using a scoliometer), coronal balance, shoulder height difference, and low back pain. We radiographically evaluated curve type, thoracic or thoracolumbar curve direction, curve magnitude and flexibility, apical vertebral rotation, curve length, coronal balance, sagittal balance, shoulder height difference, thoracic kyphosis, and the Risser sign. Results: Neural axis abnormalities were detected in 24 patients (6.3%). Abnormal MRI findings were significantly more common in males than in females and were associated with increased thoracic kyphosis. However, there were no significant differences in terms of the other measured parameters. Conclusions: Among the patients with presumed AIS who received preoperative whole-spine MRI, 6.3% had neural axis abnormalities. Males and patients with increased thoracic kyphosis were at a higher risk.
이춘성,황창주,조재환,이동호,양재준,박세한 대한척추외과학회 2022 대한척추외과학회지 Vol.29 No.3
Study Design: Cross-sectional study. Objectives: To demonstrate normative values for various parameters of spinal sagittal global balance in the pediatric population and elucidate whether these parameters change during growth. Summary of Literature Review: While sagittal parameters for adults have been thoroughly evaluated, relatively few studies have reported normal values and changing trends of sagittal parameters in the pediatric population. Materials and Methods: A total of 200 patients aged 5–20 years were evaluated. Cervical lordosis, thoracic kyphosis, lumbar lordosis, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), pelvic incidence–lumbar lordosis (PI-LL), C2–C7 sagittal vertical axis (SVA), C7 SVA, T1 pelvic angle (T1PA), and the spinosacral angle (SSA) were assessed. Results: Significant positive correlations were found between age and PI (r=0.297, p<0.001), SS (r=0.184, p=0.009), and PT (r=0.203, p=0.004). Among the global sagittal parameters, T1PA (r=0.345, p<0.001) demonstrated a significant association with age, whereas C7 SVA (r=−0.053, p=0.464) and SSA (r=−0.029, p=0.194) were not significantly associated. Furthermore, PI-LL was significantly smaller in the ≥12-year age group than that in the ≤11-year age group (p=0.037). Conclusions: In conclusion, PI, PT, and SS increase during growth owing to the increasing size of the pelvis. T1PA accordingly increases with an increase in pelvic parameters, whereas no other global sagittal parameters, such as C7 SVA or SSA, change during childhood. The changing trends and normative values of each parameter demonstrated in the present study should be considered when planning long-level fusion operations for pediatric patients.