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박재형 牧園大學校 建築·都市硏究센터 1997 建築·都市環境硏究 Vol.5 No.-
The objective of this work is to present an formulation to solve structural optimization problems of trusses. Basically this algorithm use SQP method. Unfortunately, the problem of optimizing structural has very challenging, especially the structural problem of optimizing the highrized buildings. It leads to optimization problems with tens of thousands (or more) of nonlinear constraints, which until recently have been out of the reach of nonlinear numerical optimization methods. Furthermore, commonly-available computers have not been powerful enough to warrant such an approach. This SQP method, therefore, has to be modified to apply to structural optimization problems. We pursue a decomposition of the problem into the state space and the sizing space, as follows: solve at each iteration the discrete equilibrium equations (Ku=P) for the state variables (u: displacement) given values of the sizing variables (A: section area). Thus, we eliminate the state equations (equilibrium equation) from the equality constraint set, and we eliminate the state variables from the set of optimization variables. As a result of this decomposition, although the state variables becomes an implicit function of the sizing variables, the dimension of the optimization problem can be greatly reduced. The examples demonstrate that the formulation presented in this study is effective for finding optimal solution to minimize the weight of structures.
박재형,Margaret M. Park,Samar Farha,Jacqueline Sharp,Erika Lundgrin,Suzy Comhair,Wai Hong Tang,Serpil C. Erzurum,James D. Thomas 한국심초음파학회 2015 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.23 No.2
Background: New 2-dimensional strain echocardiography enables quantification of right ventricular (RV) mechanics byassessing global longitudinal strain of RV (GLSRV) in patients with pulmonary arterial hypertension (PAH). However, theprognostic significance of impaired GLSRV is unclear in these patients. Methods: Comprehensive echocardiography was performed in 51 consecutive PAH patients without atrial fibrillation (40females, 48 ± 14 years old) with long-term follow-up. GLSRV was measured with off-line with velocity vector imaging (VVI,Siemens Medical System, Mountain View, CA, USA). Results: GLSRV showed significant correlation with RV fractional area change (r = -0.606, p < 0.001), tricuspid annular planesystolic excursion (r = -0.579, p < 0.001), and RV Tei index (r = 0.590, p < 0.001). It showed significant correlations with pulmonaryvascular resistance (r = 0.469, p = 0.001) and B-natriuretic peptide concentration (r = 0.351, p = 0.012). During a clinical followuptime (45 ± 15 months), 20 patients experienced one or more adverse events (12 death, 2 lung transplantation, and 15 heartfailure hospitalization). After multivariate analysis, age [hazard ratio (HR) = 2.343, p = 0.040] and GLSRV (HR = 2.122, p =0.040) were associated with adverse clinical events. Age (HR = 3.200, p = 0.016) and GLSRV (HR = 2.090, p = 0.042) were alsosignificant predictors of death. Impaired GLSRV (≥ -15.5%) was associated with lower event-free survival (HR = 4.906, p = 0.001)and increased mortality (HR = 8.842, p = 0.005). Conclusion: GLSRV by VVI showed significant correlations with conventional echocardiographic parameters indicating RVsystolic function. Lower GLSRV (≥ -15.5%) was significantly associated with presence of adverse clinical events and deaths inPAH patients.
박재형,Kenya Kusunose,Deborah H. Kwon,Margaret M. Park,Serpil C. Erzurum,James D. Thomas,Richard A. Grimm,Brian P. Griffin,Thomas H. Marwick,Zoran B. Popović 대한심장학회 2015 Korean Circulation Journal Vol.45 No.5
Background and Objectives: Right ventricular longitudinal strain (RVLS) is a new parameter of RV function. We evaluated the relationship of RVLS by speckle-tracking echocardiography with functional and invasive parameters in pulmonary arterial hypertension (PAH) patients. Subjects and Methods: Thirty four patients with World Health Organization group 1 PAH (29 females, mean age 45±13 years old). RVLS were analyzed with velocity vector imaging. Results: Patients with advanced symptoms {New York Heart Association (NYHA) functional class III/IV} had impaired RVLS in global RV (RVLSglobal, -17±5 vs. -12±3%, p<0.01) and RV free wall (RVLSFW, -19±5 vs. -14±4%, p<0.01 to NYHA class I/II). Baseline RVLSglobal and RVLSFW showed significant correlation with 6-minute walking distance (r=-0.54 and r=-0.57, p<0.01 respectively) and logarithmic transformation of brain natriuretic peptide concentration (r=0.65 and r=0.65, p<0.01, respectively). These revealed significant correlations with cardiac index (r=-0.50 and r=-0.47, p<0.01, respectively) and pulmonary vascular resistance (PVR, r=0.45 and r=0.45, p=0.01, respectively). During a median follow-up of 33 months, 25 patients (74%) had follow-up examinations. Mean pulmonary arterial pressure (mPAP, 54±13 to 46±16 mmHg, p=0.03) and PVR (11±5 to 6±2 wood units, p<0.01) were significantly decreased with pulmonary vasodilator treatment. RVLSglobal (-12±5 to -16±5%, p<0.01) and RVLSFW (-14±5 to -18±5%, p<0.01) were significantly improved. The decrease of mPAP was significantly correlated with improvement of RVLSglobal (r=0.45, p<0.01) and RVLSFW (r=0.43, p<0.01). The PVR change demonstrated significant correlation with improvement of RVLSglobal (r=0.40, p<0.01). Conclusion: RVLS correlates with functional and invasive hemodynamic parameters in PAH patients. Decrease of mPAP and PVR as a result of treatment was associated with improvement of RVLS
불감영역을 갖는 고차시스템에 대한 퍼지 PIDA 제어기
박재형,조용성,최부귀 동아대학교 정보기술연구소 2000 情報通信硏究所論文誌 Vol.8 No.1
It is very difficult to design PID controller in order to control the third order of plant because the order of plant is larger than its zeros be obtained from that controller. In a case of some plants including a unknown deadzone, the output of controller can't affect them exactly. Thus it also makes the steady-state error occur and the response characteristic become for the worse. To solve this problem, this paper propose fuzzy PIDA Controller. Fuzzy PIDA controller is proposed to control the third order of plant including a unknown deadzone. The structure of controller is reconstructed with fuzzy compensator on the conventional PIDA controller