• Journal of Mechanical Science and Technology
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• 제20권2호
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• pp.205-211
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• 2006

Among other critical conditions in rotor systems the large non-linear vibration excited by bearing non-linearity causes the rotor failure. For reducing this catastrophic failure and predictive detection of this phenomenon the analysis of orthotropic bearing non-linearity in rotor system using higher order frequency response functions (HFRFs) is conducted and is shown to be theoretically feasible as that of non-rotating structures. The complex HFRFs based on the Volterra series are newly developed for the process and investigated their features by using the simple forms of the FRFs associated with the forward and the backward modes.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2006년도 춘계학술발표대회 논문집
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• pp.206-209
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• 2006

The concept of non-linearity, which has been derived from a scientific paradigm, has generated new discourse in formative arts. The non-linearity enables various new possibilities such as, generation of diverse and dynamic space, creation of non-geometric form and space, and the shape in the space as it is in nature. This study percepts and explains the concepts of non-linearity and their principles in space modeling in the field of interior design, in terms of the philosophy of fractal geometry. We also analyze cases, which shows trends and specific embodiments of non-linear space modeling. This study will provide perspectives on the non-linearity as a new methods in the space modeling. For the study, we review the concept and characteristics of non-linearity, by examining various literatures, and developed an analyzing tool which was used to study various cases of Western and Korean interior Design.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.35-42
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• 2004

Among other critical conditions in rotor svstems the large non-linearvibration excited by bearing non-linearity causes the rotor failure. For reducing thiscatastrophic failure and predictive analysis of this phenomena the identificationanalysis of bearing non-linearity in an anisotropic rotor system using the higherorder dFRFs are developed and are shown to be theoretically feasible as innon-rotating structures. For the identification of the anisotropic rotor withanisotropic bearing non-linearity expressed by the displacement in polynomial form,the higher order dFRFs based upon the Volterra series are investigated and depicttheir features by using the simple forms of the normal and reverse dFRFs. Theyproduce additional sub-harmonic resonant peaks, which indicate the existence ofhigher order non-linearties, and show the energy transfer such that the modes fornormal and reuerse dFRFs are exchanged, which are the fundamental differencesfrom what we can expect in linear ones.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.487-494
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• 2017

The present paper deals with a theoretical study of delamination fracture in the Crack Lap Shear (CLS) functionally graded beam configuration. The basic purpose is to analyze the fracture with taking into account the material non-linearity. The mechanical behavior of CLS was described by using a non-linear stress-strain relation. It was assumed that the material is functionally graded along the beam height. The fracture was analyzed by applying the J-integral approach. The curvature and neutral axis coordinate of CLS beam were derived in order to solve analytically the J-integral. The non-linear solution of J-integral obtained was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, crack location along the beam height and material non-linearity on fracture behavior were evaluated. The J-integral non-linear solution derived is very suitable for parametric studies of longitudinal fracture in the CLS beam. The results obtained can be used to optimize the functionally graded beam structure with respect to the fracture performance. The analytical approach developed in the present paper contributes for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

• 한국자동차공학회논문집
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• 제6권2호
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• pp.228-234
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• 1998

The buckling is one of the major two nonlinear problems. One is the material non-linearity and other is the geometrical nonlinear. Material non-linearity has occurred when the buckling stress of material exceeded the yield stress of material. The material non-linearity must be taken into account when the buckling analysis of thick plate is performed. In this study, inelastic modulus that is used to calculate the buckling strength is taken to account for the material non-linearity. The results from experiments are used to formulate the semi-theoretical formula. The analysis results generated by the use of semi-theoretical formula are close to the experimental data.

• Steel and Composite Structures
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• 제23권3호
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• pp.263-271
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• 2017

A theoretical study was carried-out of mode II delamination fracture behavior of the End Loaded Split (ELS) functionally graded beam configuration with considering the material non-linearity. The mechanical response of ELS was modeled analytically by using a power-law stress-strain relation. It was assumed that the material is functionally graded transversally to the beam. The non-linear fracture was investigated by using the J-integral approach. Equations were derived for the crack arm curvature and zero axes coordinate that are needed for the J-integral solution. The analysis developed is valid for a delamination crack located arbitrary along the beam height. The J-integral solution was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, non-linear material behavior and crack location on the fracture were evaluated. The solution derived is suitable for parametric analyses of non-linear fracture. The results obtained can be used for optimization of functionally graded beams with respect to their mode II fracture performance. Also, such simplified analytical models contribute for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

• Wind and Structures
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• 제9권6호
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• pp.457-471
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• 2006

This paper is devoted to the non linear quasi-steady aerodynamic loading. A linear approximation is often used to compute the response of structures to buffeting forces. Some researchers have however shown that it is possible to account for the non linearity of this loading. This non linearity can come (i) from the squared velocity or (ii) from the shape of the aerodynamic coefficients (as functions of the wind angle of attack). In this paper, it is shown that this second origin can have significant implications on the design of the structure, particularly when the non linearity of the aerodynamic coefficient is important or when the transverse turbulence is important.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
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• pp.43-46
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• 2001

The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.

• 항공우주기술
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• 제8권2호
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• pp.1-7
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• 2009

세계최초의 정지궤도 해양탑재체인 GOCI(Geostationary Ocean Color Imager)는 정지궤도 복합위성인 COMS(Communication, Ocean, and Meteorological Satellite)에 기상탑재체, 통신탑재체와 함께 탑재되기 위해 개발되고 있다. 본 논문에서는 부분품 레벨의 응답특성을 이용한 탑재체 레벨의 복사모델 수립방법을 소개하며, 복사모델을 이용하여 각 채널의 비선형성 특성을 분석한다. 또한, 해양탑재체의 복사시험 데이터를 이용하여 각 채널의 비선형 특성을 검증한다. 분석 결과, 선형이득과 비선형이득의 함수로 표현되는 비선형성$G^3$/b는 모든 채널에 대해 동일함을 확인하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권12호
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• pp.751-758
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• 2004

This paper presents a new method to compensate the non-linearity for matrix converter drives using PQR instantaneous Power theory. The non-linearity of matrix converter drives such as commutation delay, turn-on and turn-off time of switching device, and on-state switching device voltage drop is modelled by PQR power theory and compensated using a reference current control scheme. The proposed method does not need any additional hardware and off-line experimental measurements. The proposed compensation method is applied for high performance induction motor drives using a 3 kW matrix converter system without a speed sensor. Simulation and experimental results show the proposed method using PQR power theory Provides good compensating characteristic.