• Journal of Korean Neurosurgical Society
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• 제61권1호
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• pp.28-34
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• 2018

Objective : Duplication of the vertebral artery (VA) is a rare vascular variant. This paper describes the anatomy and embryological development of duplicated VAs and reviews the clinical significance. Methods : Computed tomography (CT) angiography was performed in 3386 patients (1880 females, 1506 males) between March 2014 and November 2015. We defined duplication of the VA as a condition in which the VA has two origins that fused at different levels of the neck. Results : Ten of the 3386 patients (0.295%) who received CT angiography had a dual origin of the VA; three on the left side, and seven on the right side. In all seven with right dual origin of the VA, both limbs of the VA origin originated from the right subclavian artery. In all three patients with left dual origin of the VA, both limbs of the VA originated from the left subclavian artery and aortic arch. In all 10 patients, the medial limb of the duplicated VA was located posteriorly and medially to the common carotid artery (CCA) and anteriorly and laterally to the vertebral transverse foramen. In two patients, the medial limb of the duplicated VA was located in close proximity to the CCA. In another two patients, the medial limb of the duplicated VA was located in close proximity to the CCA, carotid bifurcation, and proximal internal carotid artery. Conclusion : Although duplication of the VA is asymptomatic in most patients, clinicians should consider this anomaly during diagnosis and treatment.

• 한국산학기술학회논문지
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• 제14권8호
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• pp.3976-3982
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• 2013

본 논문에서는 전압 제어형 카오스 신호 발생회로를 설계하고, 온도변화에 따른 특성을 해석 하였다. 제안하는 CMOS 회로로 이루어지며, 카오스 특성의 전압 제어형 오실레이터의 온도 변화에 따른 특성해석을 실시하였다. 제안하는 회로는 2상 클럭의 샘플앤드회로 3개의 MOS 소자로 이루어지는 비선형 함수 블록과 소스 팔로워로 이루어지는 레벨 쉬프터로 구성된다. SPICE 모의실험을 통하여 온도변화에 따른, 비선형함수의 전달함수 변화를 통하여, 분기도 특성, 주파수 특성 등의 카오스 다이나믹스가 변화됨변화됨을 확인 하였다. 또한 $25^{\circ}C$ 의 온도 조건에서, 제어전압 1.2 V-2.3 V 범위에서, 카오스 신호가 생성됨을 확인하였다.

• 한국농공학회지
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• 제24권2호
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• pp.76-88
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• 1982

The stream morphological characteristics of a basin have important influence upon the analysis of runoff. In this study, the laws of stream morphology-the law of average stream fall and the law of least rate of potential energy expenditure-which were derived based on the analogy of entropy in thermodynamics are introduced and their validity is analysised with the data taken from the topographic maps covering the whole Geum River system. The first law is the Law of Average Stream Fall which states that under the dynamic equilibrium condition the ratio of average fall between any two different order stream in the same river basin in unity. The second law is the law of least rate of energy expenditure which states that all natural streams are intended to choose their own course of flow such that the rate of potential energy loss per unit mass of water this course is a minimum. The parameters representing the morphological characteristics of 13 tributaries in the Geum River system such as stream bifurcation ratio and stream concavity were Computed from the Horton-Strahler's laws and are used to check the law of average stream fall. The result showed that the law of average stream fall agrees reasonably well with law of Horton-Strahler. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Based on Horton's Law and the law of average stream fall, longitudinal stream profiles can be calculated.

• Structural Engineering and Mechanics
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• 제49권4호
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• pp.427-448
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• 2014

At present, the time of easy oil and gas is over. Now, the largest part of fossil fuels is concentrated in the deepest levels of tectonic structures and in the sea shelves. One of the most cumbersome operations of their extraction is the bore-hole drilling. In connection with austere tectonic and climate conditions, their drivage every so often is associated with great and diversified technological difficulties causing emergencies on frequent occasions. As a rule, they are linked with drill string accidents. A key role in prediction of these situations should play methods of theoretical modelling. For this reason, there is a growing need for development and implementation of new numerical methods for computer simulation of critical and post-critical behavior of drill strings (DSs). In this paper, the processes of non-linear deforming of a DS in cylindrical cavity of a deep bore-hole are considered. On the basis of the theory of curvilinear flexible rods, non-linear constitutive differential equations are deduced. The effects of the longitudinal non-uniform preloading, action of torque and interaction between the DS and the bore-hole surface are taken into account. Owing to the use of curvilinear coordinates in the constraining cylindrical surface and a specially chosen concomitant reference frame, it became possible to separate the desired variables and to reduce the total order of the equation system. To solve it, the method of continuation the solution by parameter and the transfer matrix technique are applied. As a result of the completed numerical analysis, the critical states of the DS loading in the cylindrical channels of inclined bore-holes are found. It is shown that the modes of the post-critical deforming of the DS are associated with its irregular spiral curving prevailing in the zone of bottom-hole-assembly. The possibility of invariant state generation during post-critical deforming is established, condition of its bifurcation is formulated. It is shown that infinite variety of loads can correspond to one geometrical configuration of the DS. They differ each from other by contact force functions.

• Journal of Chest Surgery
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• 제13권1호
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• pp.77-81
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• 1980

We present one case of 26-year-old male having saddle block combined with mitral valvular disease [NYHA Class IV] with auricular fibrillation. The most common cause of emboli is atrial fibrillation. The clinical manifestations of saddle emboli are relatively slow due to development of collateral circulation and large size of lumen of the aorta. The 5month duration of saddle emboli in this case led to severe atrophic changes, coldness, peripheral cyanosis on the both lower extremities, and flexion deformity on the knee and ankle joint of the left lower extremity. We planned staged operation for the saddle block and for mitral stenoinsufficiency and tricuspid insufficiency, because of poor general condition of the patient. The thromboembolectomy of aortic bifurcation was performed through the transabdominal approach without trial of Fogarthy catheter embolectomy, because of expectation of the secondary inflammatory changes of the vessel wall and thrombi which was 3 cm X 1 cm X 0.5 cm in size with irregular surfaced solid in consistency. 1 month later, after thromboembolectomy, mitral valve replacement and tricuspid annuloplasty were performed, with successful early operative result. During operation organized thrombi [1 cm X 0.5 cm] in the left auricle was removed. We wonder if simple management using Fogarthy catheter might be possible to remove the thromboemboli instead of thromboembolectomy by aortotomy in this case.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.169-184
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• 2006

A close form solution of the maximum deflection for cracked columns with rectangular cross-sections was developed and thus the elastic buckling behavior and ultimate bearing capacity were studied analytically. First, taking into account the effect of the crack in the potential energy of elastic systems, a trigonometric series solution for the elastic deflection equation of an arbitrary crack position was derived by use of the Rayleigh-Ritz energy method and an analytical expression of the maximum deflection was obtained. By comparison with the rotational spring model (Okamura et al. 1969) and the equivalent stiffness method (Sinha et al. 2002), the advantages of the present solution are that there are few assumed conditions and the effect of axial compression on crack closure was considered. Second, based on the above solutions, the equilibrium paths of the elastic buckling were analytically described for cracked columns subjected to both axial and eccentric compressive load. Finally, as examples, the influence of crack depth, load eccentricity and column slenderness on the elastic buckling behavior was investigated in the case of a rectangular column with a single-edge crack. The relationship of the load capacity of the column with respect to crack depth and eccentricity or slenderness was also illustrated. The analytical and numerical results from the examples show that there are three kinds of collapse mechanisms for the various states of cracking, eccentricity and slenderness. These are the bifurcation for axial compression, the limit point instability for the condition of the deeper crack and lighter eccentricity and the fracture for higher eccentricity. As a result, the conception of critical transition eccentricity $(e/h)_c$, from limit-point buckling to fracture failure, was proposed and the critical values of $(e/h)_c$ were numerically determined for various eccentricities, crack depths and slenderness.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.692-710
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• 2018

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.

• The Korean Journal of Legal Medicine
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• 제40권2호
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• pp.61-64
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• 2016

Ehlers-Danlos syndrome type IV (EDS IV) is a hereditary disorder of the connective tissue, characterized by easy bruising, thin skin with visible veins, and spontaneous rupture of the large arteries, uterus, or bowel. EDS IV is caused by mutations of the gene for type III procollagen (COL3A1), resulting in insufficient collagen production or a defect in the structure of collagen. EDS IV can have fatal complications such as the rupture of great vessels or organs, which can cause hemorrhaging and sudden unexpected death. Here, we report a case of a 43-year-old female who collapsed after a struggle with a neighbor. In this patient, the bifurcation of the bilateral common iliac artery ruptured, with no evidence of trauma, inflammation, or atherosclerosis. Genetic analysis of COL3A1 showed the presence of a c.2771G>A (p.Gly924Arg) mutation, which may be associated with EDS IV. The forensic pathologist should consider the possibility that the spontaneous visceral or arterial rupture was caused by EDS IV. Genetic analysis is not currently a routine procedure during autopsy. However, in this case, we suggest that the patient possibly had an underlying EDS IV condition, and we recommended family members of the deceased to seek genetic analysis and counseling.