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자율신경계의 활성도 측정을 위한 Data Acquisition System의 개발 및 임상응용
신동구,박종선,김영조,심봉섭,이상학,이준하 영남대학교 기초/임상의학연구소 2001 Yeungnam University Journal of Medicine Vol.18 No.1
Background: Power spectrum analysis method is a powerful noninvasive tool for quantifying autonomic nervous system activity. In this paper, we developed a data acquistion system for estimating the activity of the autonomic nervous system by the analysis of heart rate and respiratory rate variability using power spectrum analysis. Materials and methods: For the detection of QRS peak and measurement of respiratory rate from patient's ECG, we used low-pass filter and impedance method respectively. This system adopt an isolated power for patient's safety. In this system, two output signals can be obtained: R-R interval(heart rate) and respiration rate time series. Experimental ranges are 30∼240 BPM for ECG and 15∼80 BPM for respiration. Regults: The system can acquire two signals accurately both in the experimental test using simulator and in real clinical setting. Conclusion: The system developed in this paper is efficient for the acquisition of heart rate and respiration signals. This system will play a role in research area for improving our understanding of the pathophysiologic involvement of the autonomic nervous system in various disease states.
Ultimate Flexural Strengths of Plate Girders Subjected to Web Local Buckling
신동구,조은영,김경식 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.2
The ultimate flexural strengths of bisymmetric and monosymmetric I-girders subjected to local bend-buckling in webs have been investigated by nonlinear finite element analysis incorporating post-buckling behaviors. The plate girders fabricated with high performance steel (HPS) and conventional steel were modeled three-dimensionally with thin shell elements and ultimate strength analyses were conducted utilizing versatile nonlinear techniques provided by a commercial finite element analysis (FEA) package program, ABAQUS. The constitutive relationship for both HPS and conventional steel was assumed to be elasto-plastic strain-hardening, and the initial imperfections were considered in the web panels and the residual stresses were imposed on the hypothetical built-up sections. The ultimate flexural strengths of girders with various slenderness of web were evaluated from the nonlinear FEA and compared with values predicted by the specifications in AASHTO LRFD and Eurocode 3. It has been found that the current flexural strength formulas for conventional steel girders from AASHTO LRFD and Eurocode 3 can be extended to application for HPS girders without modification.