충격압축하중을 받는 횡등방성 중실축의 과도 동적해석

오근,심우진,Oh, Guen,Sim, Woo-Jin 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.5

원형축이 축방향으로 충격하중을 받으면 외경에서 반사된 파가 축의 중앙으로 집중되어 순간적으로 큰 응력이 발생하게 된다. 본 연구에서는 여러 가지 충격 축하중을 받는 횡등방성 반-무한 원형축을 대상으로 중실축 내의 종방향 응력전파를 축대칭 유한요소법과 Houtolt 시간적분법을 이용하여 프로그램을 작성하고 수치적으로 해석하여 그 결과를 횡등방성 재료의 재료구성비에 따라 자세히 설명한다. 제시된 해법의 타당성은 본 논문 수치 결과와 기 해석된 다른 해법에 의한 수치결과의 비교를 통해 검증된다. 여러 종류의 충격하중들에 따른 파동의 결과를 2차원, 3차원적으로 제시하여 축응력 전파를 이해하는데 기본 자료가 되도록 하였다. 또한 유한요소법을 이용하여 수치해석을 함에 있어 정확한 수치결과를 얻기 위한 무차원 동특성 시간변수에 대해 기술하였다. Elastic wave propagations in the semi-infinite transversely isotropic cylinder under various kinds of longitudinal impact loads are analyzed using the axisymmetric finite element method and Houbolt time-integration scheme. For which the finite element program is newly constructed and verified through the comparison of present numerical results with those by other researchers. E-type glass-epoxy composite cylinders with different fiber volume fractions are adopted and studied in detail with dynamic responses of the isotropic cylinder. Three dimensional wave motions are given in graphic form to show the realistic view of the wave propagation. Nondimensionalized dynamic characteristic variables which relate the size of finite element mesh, the time step, and the wave speed are presented for obtaining accurate and stable numerical results.

[수상작 및 수상소감] 슬픈 노래 외 3편

오근 고요아침 2019 열린시학 Vol.24 No.4

충격인장하중을 받는 이종적층 원형축의 과도 동적해석

오근,심우진 금오공과대학교 2005 論文集 Vol.26 No.-

In this paper, axisymmetric stress waves in semi-infinite isotropic and bimaterical cylinders are analyzed numerically using the finite element technique when the longitudinal impact load is applied at free end. For which, the semi-discrete approximation and three time-integration schemes resulting in stable numerical results are adopted. The effects of material property and geometry on the propagation of stress wave are studied in detail and their dynamic results are shown in three dimensional wave motion.

Radiologic Changes of Anterior Cervical Discectomy and Fusion Using Allograft and Plate Augmentation: Comparison of Using Fixed and Variable Type Screw

오근,이철규,유남규,김상현,조기홍 대한척추신경외과학회 2013 Neurospine Vol.10 No.3

Objective: To evaluate radiologic result of anterior cervical discectomy and fusion with allobone graft and plate augmentation, and the change of radiologic outcome between screw type and insertion angle. Methods: Retrospective review of clinical and radiological data of 29 patients. Segmental angle, height and screw angles were measured and followed. The fusion rate was assessed by plain radiography and CT scans. We divided the patients into two groups according to screw type and angles. Group A: fixed screw, Group B: variable screw. Interscrew angle was measured between most upper and lower screws with Cobb’s methods. Results: Overall fusion rate was 86.2% on plain radiography. Fusion was also assessed by CT scan and Bridwell’s grading system. There was no difference in fusion and subsidence rates between two groups. Subsidence was found in 5 patients (17.2%). Segmental lordotic angle was increased from preoperative status and maximized at the immediate postoperative period and then reduced at 1 year follow up. Segmental height showed similar increase and decrease values. Conclusion: ACDF with allograft and plate showed favorable fusion rates, and the screw type and angle did not affect results of surgery.

축대칭 선형 점탄성 구조물의 정적 유한요소해석

오근,심우진,Oh Guen,Sim Woo-Jin 한국전산구조공학회 2005 한국전산구조공학회논문집 Vol.18 No.3

본 논문에서는 축대칭 형상의 점탄성 구조물이 정적 하중을 받을 때에 대한 시간영역에서의 유한요소해법의 정식화 과정을 제시한다. 또한, 여러 가지 경계조건을 갖는 점탄성 중공구나 원통 문제들의 변위나 응력 이론해들을 탄성-점탄성 상응원리를 이용하여 유도하고 제시한다. 이때 점탄성 재료는 부피변형이 탄성적이고 전단변형은 3요소로 구성된 표준선형 고체처럼 거동한다고 가정한다. 구대칭, 축대칭 및 평면변형률 유한요소모텔을 이용한 수치결과들을 유도된 이론해들과 비교하여 제시된 유한요소해법과 이론해들의 타당성과 정확성을 보인다. In this paper, the time-domain finite element formulations for axisymmetric linear viscoelastic problems, especially for the viscoelastic hollow sphere and cylinder, under various boundary conditions are presented with the theoretical solutions of them obtained by using the elastic-viscoelastic correspondence principle. It is assumed that the viscoelastic material behaves like a standard linear solid in distortion and elastically in dilatation. Numerical examples are solved based on the spherically symmetric, axisymmetric and plane strain finite element models. Good agreements are obtained between numerical and theoretical solutions, which shows the validity and accuracy of the presented method.

Single-session Coil Embolization of Multiple Intracranial Aneurysms

오근,임용철 대한뇌혈관외과학회 2013 Journal of Cerebrovascular and Endovascular Neuros Vol.15 No.3

Objective:There is no clear treatment strategy for the management of multiple intracranial aneurysms because of variable anatomical distribution, difficult identification of the aneurysm ruptured, and poor overall outcomes. The purpose of this study was to assess the efficacy and safety of single-session coil embolization for multiple intracranial aneurysms. Methods: Between September 2008 and December 2012, 209 aneurysms in 117 patients were treated at our institute. Twenty eight among the 117 patients had multiple aneurysms with a total of 71, and 60 of the 71 aneurysms underwent coil embolization in a single-session. Results: A total of 60 aneurysms were treated with a single-session coil embolization, of which the most frequent locations were in the posterior communicating artery, followed by the middle cerebral artery. Immediate post-embolization angiographies showed total occlusion in 49 (81.7%) aneurysms, remnant neck in 6 (10%), and body-filling in 5 (8.3%). Procedure-related complications had developed in 2 (3.3%) of the 60 embolized aneurysms: an asymptomatic thromboembolic event, and a partial coil protrusion without a subsequent thromboembolic complication. Conclusion: With careful evaluation of individual aneurysm characteristics and configuration, multiple intracranial aneurysms previously thought to require multimodality therapy can be safely treated in a single-session coil embolization.

내부공진을 고려한 2 자유도 보-질량 구조물의 비선형진동

오근일(Il Geun Oh),이현(Hyun Lee) 한국소음진동공학회 1993 한국소음진동공학회 학술대회논문집 Vol.1993 No.11

선형 과도 동탄성문제 해석을 위한 유한요소 수식화

오근(Guen Oh),황은하(Eun-Ha Hwang) 한국산업융합학회 2008 한국산업응용학회 학술대회 논문집 Vol.- No.-

A new finite element equation is derived by applying quadratic time integration scheme to the Gurtin's variational formulation for the analysis of the linear transient elastodynamic problems to increase the numerical accuracy. Numerical results are obtained by using the axial and axisymmetric and spherically symmetric one-dimensional bar element. and compared with the previous solutions by other researchers. Good agreements are obtained between numerical and theoretical solutions. which shows the validity and accuracy of the presented method.

밀폐된 점탄성 압력 용기의 모드 I 균열 해석

황은하,오근 금오공과대학교 2008 論文集 Vol.29 No.-

In this paper, the stress intensity factor, energy release rate and crack opening displacement are computed using the finite element method for closed axisymmetric viscoelastic cylinders with the circumferential cracks. The triangular elements with quarter point nodes are used to describe the stress singularity around the crack edge. Viscoelastic materials are assumed to behave elastically in dilatation and like a three-parameter standard linear solid. Viscoelastic relations are also derived by using the elastic-viscoelastic correspondence principle and compared with the numerical results to show the validity of the presented method.

충격내압을 받는 복합적층 중공구의 수치해

심우진,오근 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.2