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독립성분분석(ICA)법을 이용한 모드특성 추정에 관한 연구
황재승,김재형,Hwang, Jae-Seung,Kim, Jae-Hyung 대한건축학회 2011 대한건축학회논문집 Vol.27 No.5
Independent component analysis (ICA) is a method separating the mixture of signals into statistically and mutually independent ones. It has been applied to not only the Cocktail-party problem but also EEG analysis using the EEG waveform, digital signal processing, image processing and cognitive technique field actively. This study aims to propose a procedure to estimate the modal responses and mode shapes of a structure by using the ICA method from analyzed responses of the structure, which is first attempt to the architecture and civil engineering works field. It is introduced a basic concept of ICA with the fixed-point (FP) algorithm based on secant method and the kurtosis. From the concept of the separation performance of mixed-signal, modal responses and mode shape of a building structure are estimated based on ICA method. For the verification of the ICA method, a numerical simulation is performed. In the simulation, it is assumed that the mode shape and time history of the structural responses had been known through the dynamic analysis and state space analysis of a structure. Then, some parts of responses of the structure are chosen from analysed responses and those are used as input responses to estimated the modal responses and mode shape of a structure by the ICA method. From the numerical results, it is shown that the ICA method can be effectively applied to the mode separation and the estimation of modal properties of structure.
황재승,김현,권영준,정희연,Hwang, Jae-Sung,Kim, Hyun,Kwon, Young-Joon,Jung, Hee-Yeon 대한생물정신의학회 2003 생물정신의학 Vol.10 No.2
Objective:The purpose of this study was to know about the mechanism of pathogenesis of type 2 diabetes mellitus by using of blood glucose, glucoregulatory factor, insulin resistance in schizophrenic patients receiving antipsychotics. Method:Modified oral glucose tolerance tests were performed in 20 schizophrenic patients receiving haloperidol, risperidone and olanzapine. Insulin, glucagon, C-peptide and cortisol were measured in 0, 15, 45, 75 minutes after glucose loading, and insulin resistance was calculated by HOMA(homeostasis model assessment) method. Result:Olanzapine-treated patients had significant glucose elevation 45 minutes after glucose challenge. Also modest increases in HOMA IR values were detected in patients treated with olanzapine. Conclusion:Olanzapine treatment of non-diabetic patients with schizophrenia can be associated with type 2 diabetes mellitus through the elevation of glucose and insulin resistance. Elevated insulin resistance may be a causative mechanism of type 2 diabetes mellitus in patients receiving olanzapine.
모드공간 칼만필터를 이용한 비고전감쇠 구조물의 모드식별
황재승(Hwang, Jae-Seung) 대한건축학회 2022 대한건축학회논문집 Vol.38 No.11
For the visualization of dominant vibration pattern or the separation of modal response from measurements, the mode shape is very useful parameter. In this research, a modal-based Kalman filter defined in the modal space was introduced to decompose modes from one sensor response and develop a process to identify the mode shape using the correlation between the separated modes and the measured responses. It was observed that the updated modal responses by the mode shape was more precise than the originally extracted modes by modal-based Kalman filter. Furthermore, it was shown that the process can be extended to estimate the mode shape of non-classically damped structure in the state space. To verify the mode shape estimation framework proposed in this study, numerical simulations and application for the site-situ measurements were carried out. From the simulation results, it was found that the proposed modal identification technique had noise immunity; it can be applied to estimate the state space mode shape of non-classically damped structure and utilized on a system with very closely distributed modes such as a structure-tuned mass damper system.
다중동조질량감쇠기를 이용한 단순지지 슬래브의 진동 및 소음저감에 관한 연구
황재승(Hwang, Jae-Seung),홍건호(Hong, Geon-Ho),박홍근(Park, Hong-Gun) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.10
In this study, it is outlined that heavy weight floor impact noise induced by the vibration of slab can be reduced using multi tuned mass damper(MTMD) effectively. Substructure synthesis is utilized to develope analytical model of the slab coupled with MTMD and acoustic power is introduced to evaluate the performance of noise control for simplicity. Numerical analysis is carried out to investigate the effect of the properties of MTMD on the vibration and noise control of the simply supported slab. Numerical analysis shows that mass ratio of MTMD is critical on the vibration and noise control of the slab and it is also essential to reduce the vibration in higher modes of slab in the light of its great effect on the radiation of sound.
황재승(Hwang Jae-Seung),조광철(Cho Kwang-Cheol) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.2
The method proposed in the previous study to estimate modal wind load using a structural response and Kalman filtering is extended rigorously in modal space and is verified using a numerical analysis and wind tunnel test. The method is evaluated in SDOF based on an assumption that the response of a building structure is governed by the 1st modal response, but it can be generalized to MDOF structure using a modal superposition and a response decomposition method such as proper orthogonal decomposition(POD). From the numerical analysis, it is shown that acceleration response can estimate the modal wind load more precisely than displacement response and the effect of noise can be effectively reduced when an appropriate filtering is used. It is also verified that the error of natural frequency has a bad effect on the estimation of modal load more than that of damping ratio. Wind tunnel test was carried out to verify the estimation method for a simple rectangular shape stack of 210 m high with scale factor of 1/200. A Modal wind load was estimated using the acceleration obtained from numerical differentiation of the displacement at the top of the aeroelastic model. From the comparison between the acceleration of aeroelastic model and the acceleration calculated from numerical analysis, it is verified that the proposed method in this study is reliable to estimate the modal wind load.