3,795 research outputs found
하지동맥 질환의 인터벤션: 전반적 치료 계획 수립
No full textThe prevalence of lower extremity disease is increasing with age. With recent technological advancements, endovascular treatment is being performed more frequently. The treatment goal of intermittent claudication is to improve walking and reduce claudication. To achieve these goals, anatomical durability and patency are important. In patients with critical limb ischemia, the lesions are diffuse and particularly severe in below-the-knee arteries. The treatment goal of critical limb ischemia is to promote wound healing and to prevent major amputation, which is evaluated by the limb salvage rate. Primary stenting using covered or bare metal stents is a widely accepted endovascular treatment. While drug-eluting technologies with or without atherectomy are widely used in the treatment of femoropopliteal disease, balloon angioplasty is the mainstay treatment for below-the-knee intervention. CT angiography provides a road map for planning endovascular treatment in patients without absolute contraindications.하지동맥 질환의 유병률은 고연령 군에서 증가한다. 최근의 기술적 진보로 혈관 내 치료가 점점 더 많은 빈도로 시행되고 있다. 간헐적 파행의 치료 목표는 보행 능력을 향상시키고 증상을 완화시키는 것이다. 이를 위해 해부학적 내구성을 높이는 것이 중요한 전략이며 개통률이 치료 평가 기준이 된다. 임계 하지허혈을 가진 환자에서는 병변이 광범위하고 특히 무릎 아래동맥을 심하게 침범한다. 임계 하지허혈의 치료 목적은 상처 회복을 촉진하고 주요 절단을 예방하는데 있으며 사지 보존율이 평가의 기준이 된다. 장골동맥 협착의 치료에는 피복 혹은 비피복 스텐트 삽입술이 일차적 치료로 인정된다. 대퇴슬와동맥 질환은 죽종제거술과 함께 약물방출풍선 및 스텐트가 자주 사용되는 반면 무릎아래동맥 질환에서는 풍선확장술이 주요 치료 방법이다. 컴퓨터단층 혈관조영술은 절대적 금기증이 없는 환자에서 혈관 내 치료 계획 수립을 하는데 로드맵을 제공한다
Controller design for a magnetically suspended milling spindle based on chatter stability analysis
No full textThe chatter stability of a rigid milling spindle levitated by five-axis active magnetic bearings (AMBs) is studied for its chatter free cutting, as the control gains of AMBs vary. The characteristic equation for regenerative chatter loop with a delay element is described by a linear differential-difference equation, accounting for the dynamics of the AMB controllers, the uncut chip thickness equation and the cutting process as well as the rigid spindle dynamics itself. An efficient chatters stability analysis method is, then proposed to predict the stability lobes and chatter frequency in milling. The analytically predicted stability lobes are found to be in good agreement with the lobes generated by other methods available in the literature. Using the proposed method, parametric study is also performed to investigate the influences of the damping and stiffness coefficients of AMBs on the chatter free cutting conditions, as they are allowed to vary within the stable region formed by the AMB-control gains
Semi-active damping control of suspension systems for specified operational response mode
No full textA practical and effective semi-active on-off damping control law using semi-active actuators is developed for vibration attenuation of a natural, multi-degree-of-freedom suspension system, when its operational response mode is specified. It does not need the accurate system parameters and semi-active actuator dynamics. It reduces the total vibratory energy of the system including the work done by external disturbances and the maximum energy dissipation direction of the semi-active actuator is tuned to the operational response mode of the structure. The effectiveness of the control law using a single semi-active linear mount is illustrated with a three-degree-of-freedom excavator cabin suspension model. (C) 2002 Elsevier Science Ltd. All rights reserved
Ontology-based Multi-layered Knowledge Framework for Product Lifecycle Management
No full textThis paper proposes an ontology-based multi-layered knowledge framework for a product lifecycle management. Participants in a product life cycle want to share comprehensive product knowledge without ambiguity or heterogeneity. However, previous knowledge management approaches are limited in providing these aspects. Our knowledge framework has a systematic lattice structure with three product knowledge types and four layers. The three knowledge types are axioms, knowledge maps, and specialized knowledge for a domain. The four layers consist of a product context model, a product specific model, a product planning model, and a product manufacturing model. These layers represent different abstraction levels of the product knowledge conceptualization. Each layer includes the aforementioned three knowledge types in order to accommodate comprehensive knowledge and is represented with first order logic for a uniform representation. We provide formal definitions of the framework to manage comprehensive knowledge according to the proposed knowledge framework. In addition, we develop a prototype system for realization of the framework. The system will help knowledge engineers create, edit, and visualize product knowledge according to the framework and infer new knowledge with a prolog inference engine
Do Balloon Catheters have a Different Radial Force Along Their Longitudinal Axis?
No full textPurpose: This experimental study was designed to compare radial forces between the central portion and both ends of balloon catheters when dilating stenosis. Materials and Methods: Three balloon catheters of 6 and 8 mm in diameter and of variable length were tested: Mustang, Conquest, and Genoss PTA. Cylindrical modules to position balloon catheters and install the measuring tip during radial force measurements were made using a 3D printer. The measuring tip created 20% stenosis at the inner lumen. Both ends and center of the balloon catheter were located at the measuring tip. The radial force was measured after inflating the balloon catheter to the rated burst pressure. Results: For the different diameters and lengths of balloon catheters and cylinder sizes, the median inccenter, the radial rease in radial force at the distal end compared to the center was 16.5% (range: 9.8–35.2%) for Mustang, 12.4% (range: 10.3–25.5%) for Genoss, and 7.4% (range: −0.3–13.1%) for Conquest balloon catheters. Similarly, compared to that at the force at the proximal end was 10.8% greater (range: −2.9–18.3%) for Mustang, 9.9% greater (range: 3.9–22.3%) for Genoss, and 7.3% greater (range: −1.3–12.4%) for Conquest catheters. Conclusion: The radial force is greater at both ends of the balloon than at the central portion, especially at the distal end. Dilation using the distal end of the balloon catheter is a practical method that can be applied in clinical practice without additional devices when encountering resistant stenosis, especially with semi-compliant balloons. Graphical Abstract: (Figure presented.
On co-authorship for author disambiguation
No full textAuthor name disambiguation deals with clustering the same-name authors into different individuals. To attack the problem, many studies have employed a variety of disambiguation features such as coauthors, titles of papers/publications, topics of articles, emails/affiliations, etc. Among these, co-authorship is the most easily accessible and influential, since inter-person acquaintances represented by co-authorship could discriminate the identities of authors more clearly than other features. This study attempts to explore the net effects of co-authorship on author clustering in bibliographic data. First, to handle the shortage of explicit coauthors listed in known citations, a web-assisted technique of acquiring implicit coauthors of the target author to be disambiguated is proposed. Then, a coauthor disambiguation hypothesis that the identity of an author can be determined by his/her coauthors is examined and confirmed through a variety of author disambiguation experiments. (C) 2008 Elsevier Ltd. All rights reserved.X1174sciescopu
Blindsided: An Unusual Case of Ocular Ischemic Syndrome and Orthostatic Dizziness Caused by Brachiocephalic Trunk Stenosis
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