1,722,184 research outputs found
Rapid identification and management of stress-induced cardiomyopathy using POCUS after strangulation: A case report
Full text linkRATIONALE: Stress-induced cardiomyopathy (SCMP), also known as Takotsubo syndrome, is a transient cardiac condition often precipitated by severe emotional or physical stress. It is commonly mistaken for acute coronary syndrome due to similar clinical presentations. The use of point-of-care ultrasound (POCUS) provides a noninvasive, rapid diagnostic alternative that can potentially reduce the need for invasive coronary angiography, especially in emergency settings. PATIENT CONCERNS: A 26-year-old woman with type 1 diabetes presented to the emergency department following a suicidal hanging attempt. Upon arrival, she was conscious but confused, with stable vital signs. There were visible signs of strangulation, but no other immediate physical abnormalities. Laboratory tests revealed elevated cardiac enzymes and hyperglycemia. DIAGNOSES: Initial bedside POCUS revealed a reduced ejection fraction and regional wall motion abnormalities in the midportion of the left ventricle, suggesting SCMP. These findings, combined with the patient's history and absence of other contributory factors, led to a provisional diagnosis of SCMP. INTERVENTIONS: The patient was admitted to the intensive care unit for close monitoring. Serial POCUS examinations were performed to track cardiac function. Due to the rapid improvement in regional wall motion abnormalities observed through POCUS, the planned coronary angiography was deferred. OUTCOMES: The patient exhibited significant clinical improvement within 24 hours, with normalization of cardiac function as demonstrated by follow-up POCUS. Cardiac enzyme levels also returned to normal. The patient was discharged directly from the intensive care unit without the need for further invasive procedures. LESSONS: This case underscores the diagnostic value of POCUS in rapidly identifying SCMP in emergency settings, which can guide timely and appropriate management. The noninvasive nature of POCUS may reduce the need for invasive diagnostics, minimize hospital stay duration, and enhance cost-effectiveness in managing SCMP
Design and development of a metallic material with pyramidal regular structures using infrared brazing
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2010.2, [ vii, 81 p. ]정규 피라미드형 구조를 가지는 금속 소재는 다기능성과 함께 초경량, 비강성,비강도가 높은 소재이다. 산업분야에 사용되기 위해서는 생산성있는 제작방식과 설계기법이 개발되어야 한다.
첫째로 3차원 구조를 효율적으로 제작하기위해서, 절곡,적층,적외선브레이징접합의 3단계로 이루어진 적층 제작방식을 제안하였다. 기존의 전기저항발열방식에 비하여 빠른 승온,냉각의 적외선 브레이징 방법을 이용함으로써 접합시간을 현저하게 줄일 수 있었다. 초기 냉각 속도를 제어함으로써 기존 진공 브레이징과 유사한 접합강도를 얻을 수 있었다. 적외선 브레이징을 이용한 시편을 광학, 주사전자현미경으로 관찰하였을 때도 접합계면에서 결함이 발생하지 않았다.
둘째, 구조 설계를 위한 이론적 최적화를 실시하였다. 새롭게 정의한 피라미드 상단의 접합을 위한 평탄부와 적층수를 고려한 최적화를 진행하여, 최적화된 최소무게의 특성을 파악하였다. 1층,2층 구조의 최소 무게와 최적 설계 변수를 이론적으로 계산하였으며 결과적으로 새롭게 정의한 평탄부는 경량관점에 주요한 인자임을 발견하였다. 또한 적층수가 늘어날 수록 최소 무게는 감소하였다. 적합한 파손모드는 중앙함몰을 고려한 새로운 이론적 예측이 3점 굽힘 실험과 동일한 유한요소 해석 결과와 잘 일치함을 확인할 수 있었다.한국과학기술원 : 기계공학전공
원자력 발전소 설계 단순화를 위한 방법론 및 평가기준에 관한 연구
No full text학위논문(석사) - 한국과학기술원 : 핵공학과, 1987.2, [ vi, 83 p. ]The objectives of this work are to establish the design methodology aimed at resolving design complexity, and to develop evaluation criteria which can be used as a decision-making tool for design simplification.
There is a growing interest in redesign of nuclear power plant, especially in simplification of the present designs. However, there exists no clear methodology or criteria for plant simplification. Therefore, it is essential and valuable to study such problems.
In this work, by incorporating most aspects on system design applicable to simplification into general system design process, an approach for design simplification is proposed and the simplicity is defined as evaluation criteria for simplification.
Proposed design approach is based on the key concepts of Functional Independence and Information Minimization which have been proposed as axiomatic design decision rules in the manufacturing field. Design methods employed in this design approach are top-down decomposition method and regular structure method, which reflect the two design concepts.
Informational entropy concept is adopted as a measure of simplicity, and system entropy evaluation model and its quantification method are developed.
Through the case study for verifying the applicability of entropy concept, it is found that physical complexity affected by number of components, interconnections, and configurations can be quantified by the measure of system entropy, and that, in the viewpoint of understandability or system uncertainty, it can also be reduced by improving component or system reliability and installing the status monitoring instrument for component or system.
From the results of AFWS case study, it is concluded that the entropy measure is an effective decision-making tool for design simplification. Finally, the proposed design methodology is expected to contribute to the improvement of engineering design process as well as design simplification.한국과학기술원 : 핵공학과
레이스 로직회로
No full textA race logic circuit of the present invention includes: a WTA circuit for receiving an operand logic signal and outputting only a high signal which is the first to arrive among the operand logic signals; plural race lines for inputting the operand logic signal into the WTA circuit; a clock distribution line having plural delay devices connected in series, both ends of the respective delay devices being connected to a triggering line, the clock distribution line receiving an external clock and outputting a triggering signal into the triggering line; and plural operand logic signal input switches which are triggered by the triggering signal output from the triggering line, for deciding whether to input the operand logic signal into the race line. According to the race logic of the present invention makes it possible to compose various logic circuits. Especially, when realizing the race logic circuit as integrated circuits, time delay due to the transistors can be removed during the logic operation. Further, time delay in the interconnection lines is actively utilized to enhance the system speed
Prediction of mechanical behavior of spatially reinforced composites for kick motor nozzle
No full textThis paper predicts the material properties of spatially reinforced composites (SRCs) and analyzes the mechanical behavior of a kick motor nozzle manufactured from that material. To find the appropriate SRC structure for the nozzle throat that satisfies given design conditions, the equivalent material properties of the SRC are predicted using the superposition of rod and matrix stiffnesses. The kick motor nozzle considered in this study consists of graphite or SRC as the throat part, carbon/phenol as the outer surface of the entrance part and inner surface of the expansion part, and steel as the outer surface of the expansion part. The material properties in arbitrary spatial directions are predicted and compared for 3-D and 4-D SRCs suitable to an axisymmetric kick motor nozzle structure. The 4-D SRC shows the smallest and uniform deformation in the nozzle throat, which has a favorable effect on the rocket thrust. The equivalent material properties of SRC are input to analyze the mechanical behavior of the kick motor nozzle using finite element method
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Electromagnetic characteristics of frequency selective fabric composites
No full textFrequency selective fabric composites that transmit microwaves in certain frequency bands are proposed. The composites consist of carbon fibres and low-loss dielectric fibres that together build periodic patterns. Unlike existing metallic frequency selective surfaces, the frequency selective fabric composite with additional load-carrying capability showed an amount of transmission near a resonance frequency
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