• Journal of the Korea institute for structural maintenance and inspection
• /
• 제8권1호
• /
• pp.129-138
• /
• 2004

In this study we determine a dynamic analysis of the existing two-span prestressed concrete box girder bridge subjected to moving vehicle loads using the experimental measurements. The moving loads applied in this paper are classified as general travelling, suddenly brake, continuous travelling, reversely travelling and reversely travelling impact loads for increasing velocities. For each travelling load, we search dynamic behaviors and characteristic in various measuring point of box girder section. In addition, the three-dimensional numerical results analyzed by the developed finite element program using flat shell element with six degrees of freedom per a node are compared with the measured experimental data. Dynamic behaviors caused impact loads by suddenly braking, reversely travelling, are bigger than by general travelling in box girder. Three-dimensional numerical results are better than one-dimensional results.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• 제7권4호
• /
• pp.51-56
• /
• 2011

Steam generator is one of the main equipments that affect safety and long term operation in nuclear power plants. Fluid flows inside and outside of the steam generator tubes and induces vibration. To prevent the vibration the tubes are supported by AVB (anti vibration bar). When the steam generator tube contact to AVB, it is damaged by the accumulation of wear and corrosion. Therefore studies are required to determine the effects of the gap between the steam generator tube and AVB. In order to obtain the stress and the displacement distributions of the steam generator tube, three dimensional finite element analyses were performed by using the commercial program ANSYS. Using the calculated the stress and the displacement distributions, the static residual strength of the steam generator tube can be evaluated. The results show that the stress and displacement of the steam generator tube increase significantly compared with the results from a zero-gap model.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• 제19권3호
• /
• pp.346-352
• /
• 2010

Recently, the high-tech industries, such as the aerospace industry, the auto industry, and the electronics industry, are growing up considerably. Because of that, high machining accuracy and productivity of precision parts have been required. The tooling system is important part in the machining center. HSK tooling system is more suitable than BT tooling system for that of high speed machining center. It is because static stiffness and machining accuracy of HSK tooling system are higher than those of BT tooling system. In this paper, static and dynamic behavior of the HSK tooling System is analyzed according to bearing characteristics and lightweight parts. In order that, three different models of the HSK tooling system are modelled by using a 3D modeling/design program. More stable one in the models of HSK tooling system can be selected by using the FEA(Finite Element Analysis).

• Journal of the Computational Structural Engineering Institute of Korea
• /
• 제20권6호
• /
• pp.691-697
• /
• 2007

Numerical eigen analysis of beam-like structure can be easily and effectively done by various conventional beam theory-based methods. However, in case of the structures composed of composite-sectioned beams, the application of conventional numerical methods requires one to derive both equivalent material and geometry properties. In the present paper, these equivalent properties are derived by the transformed section method and the test FEM program is coded. The numerical accuracy of the proposed method is verified through the comparison with the ANSYS 3-D model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.379-382
• /
• 2004

In this paper, it is investigated in advance about the PZT-based composition for piezoelectric vibration device. The specimens of piezoelectric ceramics are made of Columbite method. The piezoelectric vibration device by this composition is designed by ATILA(Magsoft) program used FEM(Finite Element Method). The vibration device used for mobile phone must be driven in the frequency of $130{\sim}200Hz$, so the resonant frequency of piezoelectricity must adjust driven frequency bandwidth. The result of analysis by ATILA is appeared dependant property of length, width, thickness and dummy weight about resonant frequency of the piezoelectric vibration device. The size of manufactured actuator is $28{\times}12{\times}0.3mm^3(length {\times}width{\times}thickness)$ and this is bimorph type. The test of manufactured piezoelectric vibration device measure displacement, acceleration and power dissipation. The piezoelectric vibration device has the advantage more than electro-magnetic motor, however the size of manufactured device is larger than electro-magnetic motor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제17권5호
• /
• pp.552-559
• /
• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficiency replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, maxwell 3D finite element analysis program(Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 KHz and some specific conditions. The optical characteristics were measured luminance and a temperature and an optical spectrum distribution for 10 min in a one minute interval at the same time. With a goal of finding alternative materials, we show measurement results of electrical characteristics of a ring-shaped electrodeless fluorescent lamp as a function of frequency and the number of coil turns using a highly permeable($\mu$$_{r}$(equation omitted) 2,000) Mn-Zn ferrite. These results are compared with those of conventional ring-shaped electrodeless fluorescent lamp. It is found that the resistance, inductance and impedance are increased while the quality factor decreases as frequency increases.s.

• Advances in aircraft and spacecraft science
• /
• 제1권1호
• /
• pp.93-123
• /
• 2014

A variational asymptotic composite beam model has been developed for thermoelastic analysis. Composite beams, including sandwich structure and laminates, under different boundary conditions are examined. Previously developed beam model, which is based on variational-asymptotic method, is extended to incorporate temperature-dependent materials experiencing large temperature changes. The recovery relations have been derived so that the temperatures, heat fluxes, stresses, and strains can be recovered over the cross-section. The present theory is implemented into the computer program VABS (Variational Asymptotic Beam Sectional analysis). Numerical results are compared with the 3D analysis for the purpose of demonstrating advantages of the present theory and use of VABS.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• 제27권5호
• /
• pp.379-384
• /
• 2014

This article describes the dynamic behaviors of a rubber tired gantry crane(RTGC) under typical load conditions which are used in the design of gantry cranes. In order to investigate the dynamic characteristics of an RTGC, we developed a finite element crane model for its huge structure. The finite element model was validated with the modal test results, e.g., natural frequencies and normal modes. And other components of RTGC were converted into detailed 3D CAD models and finally transformed to rigid body models in a dynamic simulation program ADAMS. The load conditions considered in this paper were a normal operating condition(OP1) and container hanging condition with no external loads. As a result, we could find there was large influence of crane's vibration owing to its structural stiffness and deformation. And the vibration of crane could made the movements of RTGC, which occurs crash or malfunction of crane works.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제38권5호
• /
• pp.271-275
• /
• 2012

Objectives: This study evaluated a range of fixation methods to determine which is best for the postoperative stabilization of a mandibular osteotomy using three-dimensional finite element analysis of the stress distribution on the plate, screw and surrounding bone and displacement of the lower incisors. Materials and Methods: The model was generated using the synthetic skull scan data, and the surface model was changed to a solid model using software. Bilateral sagittal split ramus osteotomy was performed using the program, and 8 different types of fixation methods were evaluated. A vertical load of 10 N was applied to the occlusal surface of the first molar. Results: In the case of bicortical screws, von-Mises stress on the screws and screw hole and deflection of the lower central incisor were minimal in type 2 (inverted L pattern with 3 bicortical repositioning screws). In the case of plates, von-Mises stress was minimal in type 8 (fixation 5 mm above the inferior border of the mandible with 1 metal plate and 4 monocortical screws), and deflection of the lower central incisor was minimal in types 6 (fixation 5 mm below the superior border of the mandible with 1 metal plate and 4 monocortical screws) and 7 (fixation 12 mm below the superior border of the mandible with 1 metal plate and 4 monocortical screws). Conclusion: Types 2 and 6 fixation methods provide better stability than the others.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• 제5권3호
• /
• pp.107-115
• /
• 1985

For the finite deflection analysis of plates with initial deflections subjected to uniaxial compression, the formulation of incremental finite strip method is made and has been incorporated into a computer program. A new in plane displacement function varying along the load: direction has been derived from the out-of-plane displacement function by considering the curvature of a plate. Either incremental load type analysis or incremental displacement type analysis may be selected to solve incremental equibrium equations in the program. The following results have been obtained: 1. Incremental displacement type analysis is superior to incremental load type analysis in that the former converges more rapidly than the latter. 2. The finite strip method using the new displacement function gives as accurate results as analytical method and other finite element methods.