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요추부 협착증 치료를 위한 극돌기 삽입술의 생체역학적 효과 분석
이희성,첸웬밍,송동률,권순영,이권용,이성재,Lee Hui-Sung,Chen Wen Ming,Song Dong-Ryul,Kwon Soon-Young,Lee Kwon-Yong,Lee Sung-Jae 대한의용생체공학회 2006 의공학회지 Vol.27 No.5
Many types of interspinous distraction devices (IDDs) have been recently developed as an alternative surgical treatment to laminectomy and fusion with pedicle screws for the treatment of the lumbar spinal stenosis (LSS). They are intended to keep the lumbar spine in a slightly flexed posture to relieve pain caused by narrowing of the spinal canal and vertebral foramen. However, their biomechanical efficacies are not well known. In this study, we evaluated the kinematic behaviors and changes in intradiscal pressure (IDP) of the porcine lumbar spine implanted with IDD. For kinematics analysis, five porcine lumbar spines (L2-L6) were used and the IDD was inserted at L4-L5. Three markers (${\phi}{\le}0.8mm$) were attached on each vertebra to define a rigid body motion for stereophotogrammetric assessment of the spinal motion in 3-D. A moment of 7.5Nm in flexion-extension, lateral bending, and axial rotation were imparted with a compressive force of 700N. Then, IDD was implanted at L3-L4. IDPs were measured using pressure transducer under compression (700N) and additional extension moment (700N+7.5Nm). In kinematic behaviors, insertion of IDD resulted in statistically significant decrease 42.8% at the implanted level in extension. There were considerable changes in ROM at the adjacent levels, but statistically insignificant. In other motions, there were no significant changes in ROM as well regardless of levels. IDPs at the surgical level (L3-L4) under compression and extension moment decreased by 12.9% and 18.8% respectively after surgery (p<0.05). At the superiorly adjacent levels, IDPs increased by 19.4% and 12.9% under compression and extension, respectively (p<0.05). Corresponding changes at the inferiorly adjacent levels were 29.4% and 6.9%, but they were statistically insignificant (p>0.05). The magnitude of pressure changes due to IDD, both at the operated and adjacent levels, were far less than the previously reported values with conventional fusion techniques. Our experimental results demonstrated the IDDs can be very effective in limiting the extension motion that may cause narrowing of the spinal canal and vertebral foramens while maintaining kinematic behaviors and disc pressures at the adjacent levels.
분포형 모델을 이용한 유역내 이동강우(MOVING STORM)의 유출해석(1) -모델의 개발-
최계원,이희성,안상진,Choe, Gye-Won,Lee, Hui-Seong,An, Sang-Jin 한국수자원학회 1992 물과 미래(한국수자원학회지) Vol.25 No.1
유역내 공간적 및 시간적 분포특성을 가진 이동강우를 해석하기 위하여 분포형 모델을 개발하였으며 이 유역모델은 지표면 흐름과 하천망 흐름으로 나누어 유출을 해석하였다. 지표면의 흐름은 2차원의 연속방정식과 운동량 방정식을 이요하였는데 kinematic 이론을 도입하여 운동량 방정식을 간략화 하였으며 하천망 흐름은 하천망을 일체로 하여 1차원의 연속방정식과 운동량방정식들을 이용하였다. 기본방정식들의 수치해석법으로 지표면의 흐름은 유한요소법을 이용하였으며 하천망에 대한 해석은 음해법의 유한차분법을 이용하였다. 모델은 특히 이동강우에 있어서 중요한 특색인 공간적 및 시간적 특성을 효과적으로 해석할 수 있도록 개발되었다. 또한 모델은 구성된 행렬의 특징을 이용하였는데, 지표면 유출모델은 Gauss 소거법을 이용하여 그해를 구하였으며 하천망 해석은 double sweep 방법을 적용하기 위한 여러 종류의 순환계수방정식을 제안하였고 이를 이용하여 그 해를 구하였다. In this paper for simulating spatially and temporally varied moving storm in a watershed a distributed model was developed. The model is conducted by two major flow simulations which overland flow simulation and channel network flow simulation. Two dimensional continuity equation and momentum equation of kinematic approximation are used in the overland flow simulation. On the other hand, in the channel networks simulation two types of governing equations which are one dimensional continuity and momentum equations between two adjacent sections in a channel, and continuity and energy equations at a channel junction are applied. The finite element formulations were used in the overland flow simulation and the implicit finite difference formulations were used in the channel network simulation. The finite element formulations for the overland flow are analyzed by the Gauss elimination method and the finite difference formulations for the channel network flow are analyzed by the double sweep method having advantages of computational speed and reduced computer storages. Several recurrent coefficient equations for channel network simulation are suggested in the paper.
손명선(Myung Sun Son),이희성(Hui-Sung Lee),최양규(Yang Gyu Choi) 한국도시철도학회 2015 한국도시철도학회논문집 Vol.3 No.3
The safety culture of an organization is the product of individual and group values, attitudes, perceptions, competencies, and patterns of behavior that determine the commitment, the style and proficiency, and an organization’s health and safety management. A good safety culture includes effective, appropriate safety management systems; strong safety leadership & commitment from management; participation and involvement of the workforce; and organizational learning and continuous improvement. This paper will introduce the safety culture inspection standards and process in Korea Railway. The main purpose is to get a better understanding of safety culture and to develop measuring tool. First of all we developed the composition factor of safety culture and the question set. And we prepared the base of computerization of safety culture measurement by developing of evaluation standards and weighted value.
Chen Wen-Ming,Ahn Yoon-Ho(안윤호),Lee Hui-Sung(이희성),Moon Soo-Jung(문수정),Lee Kwon-Yong(이권용),Lee Sung-Jae(이성재) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The endplate that lies between the vertebral body and intervertebral disc is a structure of significant physiological importance. However, mechanically the end-plate appears to be a “weak link” and its fracture pattern presents an age-related phenomenon. In current study, the effects of simulated degenerative changes in the lumbar disc and vertebral body on the endplate were examined using finite element (FE) analysis. For this purpose, an intact lumbar functional spinal unit (FSU) of L3-4 FE model was constructed and another three degenerative models were made by modifying the intact one. A mildly degenerated disc was simulated by removing the hydrostatic capacities of the nucleus and making the disc stiffer than a normal one. The severe degenerated disc, made by “nuclotomy”, was assumed to be void of nucleus. The possible alterations in bone quality due to osteoporosis were simulated by adjusting the corresponding material properties of bony structures. Under axial compression of 2000N, compared to the intact case, the model with “stiffer” disc showed an 82.4% decrease in tensile stress in posterior region, a 22.5% increase in compression in the mid region of the endplate respectively; while compressive stress generated anteriorly. The “nucleotomy” case showed reversed stress states in all regions of the endplate correspondingly. As to the “osteoporosis” model, there were 32% and 50.6% increases in the tensile stress in posterior and anterior regions of the endplate respectively. Based on these results, the failure patterns could be predicted. We concluded that the stress and strain distributions in endplate under axial loading were highly dominated by its adjacent structures. Both the degenerated disc and osteoporosis may have a pronounced impact on the structural failure of the endplate, and the possible fracture patterns predicted by FE model might be used as references for the clinical assessment of the failure mechanism of the endplate.