• Journal of Korean Neurosurgical Society
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• 제38권5호
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• pp.355-358
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• 2005

Objective : The purpose of this study is to analyze the patterns of intervertebral disc enhancement seen in infectious spondylitis, differentiate between two groups[tuberculous vs pyogenic spondylitis]. Methods : Between January 1994 and December 2002, 83patients underwent operative procedure with confirmed to histopathologic evaluation. Magnetic resonance[MR] images were obtained in all patients and were analyzed retrospectively. 57patients had tuberculosis and 26patients were infected by pyogens. The patterns of gadolinium enhancement of disc were classified into 4 types[post's classification] : Type I, non-enhancing; Type II, enhancement of the peripheral rim; Type III, Type II with central area and partial endplate; Type IV, general enhancement. Results : The enhancement patterns observed were as follows : Common pattern of tuberculous spondylitis was Type II, and pyogenic spondylitis was Type III. [p < 0.01] This difference may result from pathophysiologic varieties of organisms. Conclusion : Careful preoperative MR analysis of the patterns of disc enhancement occuring in infectious spondylitis can be useful for differentiating between the tuberculous and pyogenic spondylitis.

• Journal of Korean Neurosurgical Society
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• 제58권2호
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• pp.147-149
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• 2015

A Schmorl's node is defined as a simple endplate intravertebral herniation resulting from trauma or idiopathic causes. Although Schmorl's nodes have been considered clinically insignificant, they might indicate an active symptomatic process or cause serious complications. In this study, we report an interesting case of complete separation of a vertebral body caused by an untreated Schmorl's node accompanying severe osteoporosis. To our knowledge, this is the first clinical report in the published literature to evaluate the complete separation of a vertebral body associated with a Schmorl's node.

• Annals of Clinical Neurophysiology
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• 제9권2호
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• pp.51-58
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• 2007

Autoimmune myasthenia gravis (MG) is the neuromuscular junction disorder mostly caused by antibody against the acetylcholine receptor (AChR antibody) at the muscle endplate. The goal of treatment is to induce and maintain remission, i.e., absence of symptoms, with the least cost-to-benefit ratio. Although corticosteroids are effective in inducing remission in most patients, they have numerous potentially serious adverse effects with their long-term use. In addition, some patients do not respond or are intolerant to the conventional treatment. In this article, we discuss the difficulties encountered in long-term immunosuppressive treatment of MG, and review useful tips for the use of corticosteroids. Long-term immunosuppressive agents that can be used in steroid-refractory or -dependent patients will be reviewed with their safety profiles and efficacy in MG.

• Journal of Korean Neurosurgical Society
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• 제45권4호
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• pp.213-218
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• 2009

Objective : This study is a retrospective clinical study over more than 4 years of follow up to understand the mechanism of load sharing across the graft-bone interface in the static locking plate (SLP) fixation compared with non-locking plate (NLP). Methods : Orion locking plates and Top non-locking plates were used for SLP fixation in 29 patients and NLP fixation in 24 patients, respectively. Successful interbody fusion was estimated by dynamic X-ray films. The checking parameters were as follows : screw angle (SA) between upper and lower screw, anterior and posterior height of fusion segment between upper and lower endplate (AH & PH), and upper and lower distance from vertebral endplate to the end of plate (UD & LD). Each follow-up value of AH and PH were compared to initial values. Contributions of upper and lower collapse to whole segment collapse were estimated. Results : Successful intervertebral bone fusion rate was 100% in the SLP group and 92% in the NLP group. The follow-up mean value of SA in SLP group was not significantly changed compared with initial value, but follow-up mean value of SA in NLP group decreased more than those in SLP group (p=0.0067). Statistical analysis did not show a significant difference in the change in AH and PH between SLP and NLP groups (p>0.05). Follow-up AH of NLP group showed more collapse than PH of same group (p=0.04). The upper portion of the vertebral body collapsed more than the lower portion in the SLP fixation (p=0.00058). Conclusion : The fused segments with SLP had successful bone fusion without change in initial screw angle, which was not observed in NLP fixation. It suggests that there was enough load sharing across bone-graft interface in SLP fixation.

• 한국강구조학회 논문집
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• 제28권6호
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• pp.439-448
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• 2016

확장단부판 접합부는 강구조물의 보-기둥 접합부 혹은 변단면 부재로 구성된 PEB 구조시스템에 적용되는 접합부의 한 형태이다. 확장단부판 접합부는 접합부를 구성하는 단부판의 두께, 고장력볼트의 게이지 거리, 고장력볼트 축부의 직경, 고장력볼트의 개수 등의 영향으로 상이한 거동특성을 나타낸다. 확장단부판 접합부는 미국 및 유럽 등지에서는 다양한 형태로 강구조물의 기둥-보 접합부에 적용되고 있으나 우리나라에서는 널리 적용되고 있지 않다. 이러한 이유로는 확장단부판 접합부에 대한 설계강도식 제안, 접합부상세 제안, 내진성능 평가, 제작 및 시공지침서 개발 등이 적절히 이루어지지 못하고 있기 때문이다. 따라서 이 연구는 비보강 확장단부판 접합부의 국내 적용을 위한 기초자료를 제공하기 위하여 진행하였다. 이를 위하여 두께 12mm의 비보강 확장단부판에 대한 비선형 유한요소해석 및 실험을 수행하였다.

• 한방재활의학과학회지
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• 제30권4호
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• pp.143-154
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• 2020

Objectives To analyze the prognosis of patients with low back pain according to the severity of abnormal lumbar lordotic angle and Ferguson's angle. Methods Data from electronic medical record of a total of 199 patients hospitalized in Korean medicine hospital were analyzed. With the sagittal view of lumbar spine X-ray, lumbar lordotic angle was defined as the angle between the superior endplate of L1 with the inferior endplate of L5. Ferguson's angle was defined as the angle between the superior surfaces of the sacral with a horizontal line. 'Measure Cobb's Angle Tool' of 'INFINITT PACS' was used to measure both angles. Lumbar lordotic angle and Ferguson's angle were subdivided into five sections. The number of days from onset and the duration of hospitalization were analyzed in each section. Results Severe hypolordotic lumbar lordotic angle group were found to have longer medical history and hospitalization duration than the control group. The ratio of long-term hospitalization (over 15 days) and chronic medical history (over 180 days) of patients with severe hypolordotic Ferguson's angle were significantly higher than the control group. The ratio of patients with chronic medical history (over 180 days) was significantly higher in severe hyperlordotic Ferguson's angle group than the control group. Conclusions Severe hypolordotic lumbar lordotic angle was related to patient's prognosis. Both severe hyperlordotic and severe hypolordotic Ferguson's angle were found to be related to patient's prognosis. However, a moderate loss of lumbar lordotic angle and Ferguson's angle was not related to prognosis of low back pain patients.

• 대한기계학회논문집A
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• 제36권1호
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• pp.29-35
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• 2012

척추관 협착증은 감압술과 융합술 그리고 인공추간판 치환술 등이 있으며, 2000년대 중반부터는 인공추간판 치환술이 널리 시술되고 있다. 인공추간판의 연구는 추간판의 자유도 및 추체의 굴곡-신전, 측굴전, 축회전에 대한 해석이 핵심기술이지만, 시술 후 수년이 경과하여 발생하는 피로파손이 새롭게 큰 문제점으로 대두되고 있다. 따라서 인공추간판 연구는 슬라이딩 코어의 피로특성 및 내구성 향상에 집중되어야 한다. 본 연구에서는 세계적으로 가장 많이 사용되는 인공추간판 제품(SB Charit$\acute{e}$ III)을 기초로 유한요소모델을 제작하고, 슬라이딩 코어의 곡률반경과 마찰계수의 변화가 von-Mises 응력과 접촉압력에 미치는 영향을 평가하였다. 이와 같은 결과를 바탕으로 새로운 인공추간판 모델들 (Model-I, -II, -III)을 제안하고 일정수명 후 발생할 수 있는 슬라이딩 코어의 피로파손 거동에 대해 SB Charit$\acute{e}$ III의 결과와 비교 평가하였다.

• Korean Journal of Radiology
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• 제23권6호
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• pp.638-648
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• 2022

Objective: The study aimed to investigate the diurnal variation in cervical disc hydration and its relationship with cervical degeneration. Materials and Methods: C3-C7 discs of 86 prospectively enrolled participants (37 males, 49 females; mean age ± standard deviation, 23.5 ± 2.5 years) were assessed using T2 mapping in the morning and evening. All discs were stratified by Miyazaki grade or C2-C7 Cobb angle and T2 values (T2). The degree of diurnal T2 variation (T2-DDV), defined as (morning T2 - evening T2)/morning T2 x 100%, was measured for the entire disc, annulus fibrosus (AF), nucleus pulposus (NP), and endplate zones. Results: T2 of the entire disc decreased significantly after the daytime load (p < 0.001), with a T2-DDV of 13.3% for all discs and 16.0%, 12.2%, and 13.0% for healthy (grade I), mild degenerative (grade II), and advanced degenerative (grade III/IV) discs, respectively. T2 of regional NPs and AFs decreased significantly from morning to evening (p ≤ 0.049) except in the healthy anterior inner AF (p = 0.092). Compared with healthy discs, mild degenerative discs displayed lower T2 and T2-DDV in regional NPs (p < 0.001). Advanced degenerative discs showed higher T2-DDV in the anterior inner AF compared with healthy discs (p = 0.050). Significant diurnal T2 changes in the endplate zones were observed only in healthy discs (p = 0.013). Cervical discs in the low Cobb angle group showed higher T2-DDV in the anterior AFs and anterior NP and lower T2-DDV in the posterior AF than those in the high Cobb angle group (p ≤ 0.041). Conclusion: This study characterized the diurnal variation in hydration of the cervical discs as assessed using T2 mapping and revealed early chemo-mechanical coupling dysfunction in degenerating discs. Cervical sagittal alignment on MRI can affect the diurnal stress patterns of the cervical discs. T2 mapping is sensitive to disc biomechanical dysfunction and offers translational potential from biomechanical research to clinical application.

• Steel and Composite Structures
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• 제36권4호
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• pp.427-446
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• 2020

This paper carries out the progressive collapse analysis of stainless steel composite beam-to-column joint sub-models and moment-resisting frames under column removal scenarios. The static flexural response of composite joint sub-models with damaged columns was initially explored via finite element methods, which was validated by independent experimental results and discussed in terms of moment-rotation relationships, plastic hinge behaviour and catenary actions. Simplified finite element methods were then proposed and applied to the frame analysis which aimed to elaborate the progressive collapse response at the frame level. Nonlinear static and dynamic analysis were employed to evaluate the dynamic increase factor (DIF) for stainless steel composite frames. The results suggest that the catenary action effect plays an important role in preventing the damaged structure from dramatic collapse. The beam-to-column joints could be critical components that influence the capacity of composite frames and dominate the determination of dynamic increase factor. The current design guidance is non-conservative to provide proper DIF for stainless steel composite frames, and thus new DIF curves are expected to be proposed.

• 한국항공우주학회지
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• 제35권6호
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• pp.483-488
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• 2007

경계요소법을 이용하여 동체에 탠덤 날개를 결합한 FAST가 비평면 지면을 비행할 때의 공력 특성을 파악하였다. 본 수치해석 기법을 이용하여 계산한 결과를 실험 및 타 전산해석 결과와 비교하여 검증을 수행하였다. 날개-동체를 결합한 운송체의 공력 특성을 분석하여 안정성 확보 및 충분한 공기부상력을 가지도록 운송체 상부의 탠덤 날개를 배치하는 공력설계를 수행하였다. FAST에서 탠덤 날개가 동체의 전두부와 후두부에 위치하고, 하단 익단판을 설치하였을 때 최대 양력 성능을 얻을 수 있었다. FAST의 안정성은 탠덤날개의 플래퍼론을 이용하여 확보 가능하다.