• International Journal of Automotive Technology
• /
• 제5권3호
• /
• pp.189-194
• /
• 2004

The viscoelastic layer material is widely used to control the noise and vibration characteristics of the panel structure. This paper describes the design technology of the effective vibration damping treatment using the concept of the equivalent parameter of viscoelastic layer materials. Applying the equivalent parameter concepts based on theories of shell, it is possible to simulate the finite element analysis of damping layer panel treatments on the vibration characteristics of the structure. And it is achieved the reduced computational cost and the optimal design of topological distribution for the reduction of vibration effect.

• 전자공학회논문지C
• /
• 제34C권8호
• /
• pp.64-70
• /
• 1997

This paper presents a parameter optimization method using evolutionary programming in voltage reference circuit because the designer must select appropriate parameter values of the circuit taking into consideration both powr voltage and temperature variation. In this paper, evolutionary programming is suggested as an approach for finding good parameters with which the reference voltage variation is small with respect to temperature variation. Simulation results. Simulation results show that this method is effective in circuit design.

• 대한기계학회논문집A
• /
• 제24권3호
• /
• pp.567-580
• /
• 2000

This paper proposes an integrated approach, which is independent of specimen geometry and loading type, for predicting the fatigue life of spot welded specimens. We first establish finite element models reflecting the actual specimen behaviors observed on the experimental load-deflection curves of 4 types of single spot welded specimens. Using finite element models elaborately established, we then evaluate fracture parameter J-integral to describe the effects of specimen geometry and loading type on the fatigue life in a comprehensive manner. It is confirmed, however, that J-integral concept alone is insufficient to clearly explain the generalized relationship between load and fatigue life of spot welded specimens. On this ground, we introduce another effective parameter $J_e$ composed of $J_I$, $J_{II}$, $J_{III}$, which has been demonstrated here to more sharply define the relationship between load and fatigue life of 4 types of spot welded specimens. The crack surface displacement method is adopted for decomposition of J, and the mechanism of the mixed mode fracture is also discussed in detail as a motivation of using $J_e$.

• 한국방재학회 논문집
• /
• 제10권6호
• /
• pp.131-138
• /
• 2010

본 연구에서는 저류함수법의 매개변수 추정을 위해 개발한 범용모형을 토대로 관측수문자료를 보유하고 있는 16개 댐유역에 적용하여 그 적정성을 확인하였다. 저류함수법의 기존 매개변수 추정식은 대부분 한정된 조건에서 얻어졌고 다양한 유역특성을 고려할 때 물리적 의미가 없는 값이 얻어지는 경우가 많아 미계측유역에서 적용이 회피되어 왔다. 본 연구에서 개발된 매개변수 추정결과는 이러한 문제를 보이지 않으면서도 다양한 유역특성인자의 변화에 민감하게 반응할 수 있는 특성을 보여주고 있었다. CN방법에 의해 직접적으로 도출된 유효우량과 함께 범용모형을 이용한 매개변수 추정을 토대로 미계측유역에서 저류함수법의 활용성을 높일 수 있을 것으로 기대된다.

• 천문학회보
• /
• 제37권2호
• /
• pp.159.2-159.2
• /
• 2012

In this study, we propose an effective strategy for precise orbital and geodetic parameter estimation using SLR (Satellite Laser Ranging) observations for ILRS AAC (Associate Analysis Center). The NASA/GSFC GEODYN II software and SLR normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 are utilized for precise orbital and geodetic parameter estimation. Weekly-based precise orbit determination strategy is applied to process SLR observations, and Precise Orbit Ephemeris (POE), TRF (Terrestrial Reference Frame), and EOPs (Earth Orientation Parameters) are obtained as products of ILRS AAC. For improved estimation results, selection strategies of dynamic and measurement models are experimently figured out and configurations of various estimation parameters are also carefully chosen. The results of orbit accuracy assessment of POE and precision analysis of TRF/EOPs for each case are compared with those of existing results. Finally, we find an appropriate strategy for precise orbital and geodetic parameter estimation using SLR observations for ILRS AAC.

• Steel and Composite Structures
• /
• 제31권5호
• /
• pp.469-488
• /
• 2019

We in this paper study nonlinear bending of a functionally graded porous nanobeam subjected to multiple physical load based on the nonlocal strain gradient theory. For more reasonable analysis of nanobeams made of porous functionally graded magneto-thermo-electro-elastic materials (PFGMTEEMs), both constituent materials and the porosity appear gradient distribution in the present expression of effective material properties, which is much more suitable to the actual compared with the conventional expression of effective material properties. Besides the displacement function regarding physical neutral surface is introduced to analyze mechanical behaviors of beams made of FGMs. Then we derive nonlinear governing equations of PFGMTEEMs beams using the principle of Hamilton. To obtain analytical solutions, a two-step perturbation method is developed in nonuniform electric field and magnetic field, and then we use it to solve nonlinear equations. Finally, the analytical solutions are utilized to perform a parametric analysis, where the effect of various physical parameters on static bending deformation of nanobeams are studied in detail, such as the nonlocal parameter, strain gradient parameter, the ratio of nonlocal parameter to strain gradient parameter, porosity volume fraction, material volume fraction index, temperature, initial magnetic potentials and external electric potentials.

• 한국음향학회지
• /
• 제25권1호
• /
• pp.1-6
• /
• 2006

천해에서의 수중음장 계산에서 음향 임피던스를 해저면 입력인자로서 도입하는 방안의 가능성을 고찰하였다. 먼저 탄성 해저면에서의 음파반사 특성을 고찰한 결과, 임계 접지각 이하에서 음향 임피던스는 접지각이 거의 $0^{\circ}$에 가까울 때의 임피던스 $Z_0$ 1개 값으로 근사가 가능함을 나타내었다. 이러한 특성과 'effective depth' 개념을 접목시켜 전달손실을 계산한 결과, 수중음장 계산에서 임피던스를 해저면 음향 특성을 나타내는 입력인자로 사용하는 것이 가능성이 있음을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제15권6호
• /
• pp.653-657
• /
• 2015

A new paired gate-source voltage RF capacitance-voltage (C-V) method of extracting the effective channel length and parasitic capacitance using the intersection between two closely spaced linear regression lines of the gate capacitance versus gate length measured from S-parameters is proposed to remove errors from conventional C-V methods. Physically verified results are obtained at the gate-source voltage range where the slope of the gate capacitance versus gate-source voltage is maximized in the inversion region. The accuracy of this method is demonstrated by finding extracted value corresponding to the metallurgical channel length.

• 천문학회보
• /
• 제38권1호
• /
• pp.77.2-77.2
• /
• 2013

xIn the present work, we explored the effect of the radiation on the effective impact parameter for capture in a fully general relativistic manner. To summarize our results, evidently due to the radiation drag (the Poynting-Robertson effect), critical impact parameter of point particle gets larger by the factor of two, thus, the effective cross section of the luminous relativistic star becomes 4 times larger than that of the star without radiation emission. In addition, the finite size effect of the star adds up to this growth of the effective cross section.

• Structural Engineering and Mechanics
• /
• 제6권4호
• /
• pp.411-425
• /
• 1998

The effective length factor of a framed column may be determined by means of the alignment chart procedure. This method is based on many unrealistic assumptions, among which is that all columns have the same stiffness parameter, which is dependent on the length, axial load, and moment of inertia of the column. A new approximate method is developed for the determination of effective length factors for columns in unbraced frames. This method takes into account the effects of inelastic column behaviour, far end conditions of the restraining beams and columns, semi-rigid beam-to-column connections, and differentiated stiffness parameters of columns. This method may be implemented on a microcomputer. A numerical study was carried out to demonstrate the extent to which the involved parameters affect the K factor. The beam-to-column connection stiffness, the stiffness parameter of columns, and the far end conditions of restraining members have a significant effect on the K factor of the column under investigation. The developed method is recommended for design purposes.