• 한국지진공학회논문집
• /
• 제10권6호
• /
• pp.103-114
• /
• 2006

강제 진동 실험은 구조물의 수학적 모델과 실제 모델의 상관관계를 입증하여 구조물의 성능을 정확히 평가하기 위해 중요하기 때문에, 동적 및 정적 가진 실험을 통해 구조물의 내진성능을 평가하는 다양한 기법이 사용되고 있다. 본 논문에서는 복합 질량형 감쇠기(Hybrid Mass Damper, HMD)를 이용하여 지진하중을 모사하는 실물크기 철골조 구조물의 강제진동실험이 수행되었다. ANSYS를 사용하여 구조물의 유한요소 해석모델을 구축하였고, 강제진동 실험을 통해 얻은 계측데이터를 사용하여 이 해석모델을 갱신하였다. 의사 지진 가진 실험은 HMD에 의해 유도된 층응답이 실험을 통해 갱신된 유한요소모델을 사용한 수치해석 응답과 일치함을 보여준다.

• Steel and Composite Structures
• /
• 제47권1호
• /
• pp.79-90
• /
• 2023

Nonlinear forced vibration properties of three-layered plates containing graphene platelets (GPL) filled skins and an auxetic core have been inquired within the present paper. Owning reduced weight as well as reduced stiffness, rectangle-shaped auxetic cores have been frequently made from novel techniques such as additive manufacturing. Here, the rectangle shape core is amplified via the graphene-filled layers knowing that the layers possess uniform and linear graphene gradations. The rectangle shape core has the equivalent material specifications pursuant to relative density value. The sandwich plate is formulated pursuant to Kirchhoff plate theory while a numerical trend has been represented to discretize the plate equations. Next, an analytical trend has been performed to establish the deflection-frequency plots. Large deflections, core density and GPL amplification have showed remarkable impacts on dynamic response of three-layered plates.

• 국제학술발표논문집
• /
• The 3th International Conference on Construction Engineering and Project Management
• /
• pp.1075-1080
• /
• 2009

Recently, the building construction industry has been forced to cope with lack of skilled labor. A robot-based construction automation system should help overcome crucial troubles which may be caused by this phenomenon. In particular, it is vital to propose design for automation (DFA). Quality function deployment (QFD) is applied a systematic aid in determining the design reflecting customer's needs. This study employs the QFD approach to plan the component designs of an effective automation process, and presents the development process of DFA with an illustrative project. As a result, the study identifies the developers' design requirements for automated construction and weights them by their importance indices.

• 소음진동
• /
• 제8권5호
• /
• pp.949-956
• /
• 1998

Complex and large lattice type structures are frequently used in design of bridge, tower, crane and aerospace structures. In general, in order to analyze these structures we have used the finite element method(FEM). This method is the most widely used and powerful method for structural analysis lately. However, it is necessary to use a large amount of computer memory and computational time because the FEM requires many degrees of freedom for solving dynamic problems exactly for these complex and large structures. For analyzing these structures on a personal computer, the authors developed the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficient matrix which is related to force and displacement vector at each node. And we suggested TSCM for free vibration analysis of complex and large lattice type structures in the previous report. In this paper, we formulate forced vibration analysis algorithm for complex and large lattice type structures using extened TSCM. And we confirmed the validity of TSCM through computational results by the FEM and TSCM, and experimental results for lattice type structures with harmonic excitation.

• 한국소음진동공학회논문집
• /
• 제13권11호
• /
• pp.852-859
• /
• 2003

In order to meet the growing demands for higher storage density as well as lower noise level, the spindles in hard disk drives are to be supported by hydrodynamic bearings in place of conventional ball-type ones. However, the existing models are inappropriate to apply to accurate prediction of vibration characteristics because the HDD spindle tends to take quite a complex shape to secure its performance and cost-effectiveness. In this context, this paper treats analysis of free and forced vibrations of such-designed HDD spindles based on more sophisticated models and validations via experiments. Remarkably, to this end all the components in the system are modeled as elastic adopting the finite element method.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.598-604
• /
• 2003

In order to meet the growing demands for higher storage density as well as lower noise level, the spindles In hard disk drives are to be supported by hydrodynamic bearings in place of conventional ones. However, the existing models are inappropriate to apply to accurate Prediction or vibration characteristics because the Inn spindle tends to take quite a complex shape to secure the performance of the new type bearings. In this context, this paper treats analysis of free and forced vibrations of such-designed HDD spindles based on more sophisticated models and validation by means of experiments. Remarkably, to this end each component in the system is modeled as elastic adopting the finite element method.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.698-701
• /
• 2005

Nowadays, because of the frequent market change and variable customer's requirements, product's life-circle is becoming shorter. So, automobile companies are forced to rapidly develop new products and efficiently reduce both manufacturing lead time and cost, with the world level quality. Among them, Press Die is not only just a bottle neck but also an important resource exerting certain effect in quality of car body appearance. Since 2000, due to efforts to reduce the time of design phase, many companies have used 3D design methods. Actually the method didn't reduce the period of design because the company didn't develop the best practice. This paper wish to solve this problem by modular based hybrid dies template.

• Structural Engineering and Mechanics
• /
• 제82권4호
• /
• pp.517-542
• /
• 2022

The effect of mean angle of wind attack on the flutter critical wind speed of two generic bridge deck cross-sections, viz, one closed box type streamlined section (deck-1) and closed box trapezoidal bluff type section with extended flanges/overhangs (deck-2) type of section have been studied using Computational Fluid Dynamics (CFD) based forced vibration simulation method. Owing to the importance of the effect of the amplitude of forcing oscillation on the flutter onset, its effect on the flutter derivatives and flutter onset have been studied, especially at non-zero mean angles of wind attack. The flutter derivatives obtained have been used to evaluate flutter critical wind speeds and flutter index of the deck sections at non-zero mean angles of wind attack studied and the same have been validated with those based on experimental results reported in literature. The value of amplitude of forcing oscillation in torsional degree of freedom for CFD based simulations is suggested to be in the range of 0.5° to 2°, especially for bluff bridge deck sections. Early onset of flutter from numerical simulations, thereby conservative estimate of occurrence of instability has been observed from numerical simulations in case of bluff bridge deck section. The study aids in gaining confidence and the extent of applicability of CFD during early stages of bridge design, especially towards carrying out studies on mean incident wind effects.

• 한국소음진동공학회논문집
• /
• 제15권6호
• /
• pp.749-756
• /
• 2005

This paper presents vibration analyses of hard disk drive (HDD) spindle systems based on the finite element method. The systems under investigation have a cantilevered shaft rotating on hydrodynamic bearings. In particular, the influence of stator's flexibility on major modes has been taken into account in dual ways lumped and distributed-parameter model approfches. Even the latter employs relatively macroscopic elements instead of extremely fine ones Popular in commercial codes. In order to prove the effectiveness of such formulated models, two types of HDD prototypes featuring different hub and stator structures are selected as examples. Compared to the first, the second type has a reinforced stator that would raise the natural frequency of the hub's translational (or sideway) mode. Both free and forced vibration characteristics are computed, and subsequently compared with the experimental data. It is our conclusion that Particularly the Proposed distributed model method is an efficient design tool for state-of-the-art HDD spindle systems.

• 설비공학논문집
• /
• 제10권5호
• /
• pp.535-549
• /
• 1998

A numerical study for performance analysis of a counterflow type forced draft tower and natural draft cooling tower has been performed based on the method using the finite volume method with non-orthogonal body fitted and non-staggered grid system. For solving the coupling problem between water and air, air enthalpy balance, moisture fraction balance, water enthalpy balance, and water mass balance equations are solved with Navier-Stoke’s equations simultaneously. For the effect of turbulence, the standard k-$\varepsilon$ turbulent model is implied in this analysis. The predicted result of the present analysis is compared with the experimental data and the commercial software result to validate the present study, The predicted results show good agreement with the experimental data and the commercial software result. To investigate the influence of the cooling tower design parameters such as approach, range and wet bulb temperature, parametric studies are also peformed.