• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.665-670
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• 2002

Pleasantness or quietness becomes one of the most important factors for residential designs recently. Especially for apartments, the noise generated by falling objects becomes a sensitive issue these days. To overcome the problem of the impact noise in apartments, the floor design has been changed. To reduce the transmissibility of the noise, composite floor structures are devised and implemented for the construction of apartments. In this paper, the noise reduction performance of a composite floor plate with holes is analyzed. Computational modelings for the structures are developed and its performance is evaluated by using the finite element method. The results show that the noise can be well reduced with the multi-layer composite floor plates with holes.

• Advances in aircraft and spacecraft science
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• 제5권6호
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• pp.691-729
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• 2018

In this paper the hygro-thermo-mechanical vibration and buckling behavior of embedded FG nano-plates are investigated. The Eringen's and Gurtin-Murdoch theories are applied to study the small scale and surface effects on frequencies and critical buckling loads. The effective material properties are modeled using Mori-Tanaka homogenization scheme. On the base of RPT and HSDPT plate theories, the Hamilton's principle is employed to derive governing equations. Using iterative and GDQ methods the governing equations are solved and the influence of different parameters on natural frequencies and critical buckling loads are studied.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.95-100
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• 2004

An analysis using FEM simulation was conducted to predict residual stresses and birefringence in simple compressed cylindrical glass as a preliminary part of the optimum design determination of optical lenses. The FEM simulation with the Maxwell viscoelastic constitutive model was used to predict thermal induced residual stresses and birefringence during the compression test considering stress relaxation. Also the linear photoelastic theory was introduced to calculate birefringence from the residual stress state. The simulation results were in good agreement with deformation and birefringence distribution in the existing experimental result.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.938-946
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• 2008

Fe-base amorphous alloy and two crystalline phases composite were fabricated. The effect of temperature and strain rate on mechanical properties was evaluated utilizing compression test. Mixture of non-crystalline and crystalline phases were found using X-ray diffraction (XRD) and differential thermal analysis (DTA) tests. Based on glass transition temperature and crystallization temperature. compression tests were performed in the temperature ranging from $560^{\circ}C$ to $700^{\circ}C$ with $20^{\circ}C$ interval. Relationship between microstructure, including fracture surface morphology, and mechanical behavior was studied. The peak stress of Fe-base amorphous alloy was over 2GPa and expected to have a good wear resistance, but it is expected hard to deform because of low ductility. The peak stress and elongation of two crystalline phases composite was over 1GPa and about 20%, therefore it is possible to deform high strength wear resistant materials such as engine valve.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.367.1-367
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• 2002

Recently, the noise environmental issue in compound residential areas like apartments becomes a very critical factor fer the building designers. In order to satisfy the customer need to live in a quiet environment, several interior structures for buildings are being introduced. The multi-layered composite floor plate is one of them. This structure is designed to prevent the noise generated by an object collision. (omitted)

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.805-812
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• 2003

This paper presents a method to investigate the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. Finite element model is developed for the rotating and stationary parts of a HDD spindle system separately to determine their thermal deformations by using ANSYS, a finite element program. Then, the relative position of the rotating part with respect to the stationary part is determined by solving the equilibrium equation of the contact force between upper and lower ball bearings. The validity of the proposed method is verified by comparing the theoretical natural frequencies of a HDD spindle system with the experimental ones before and after temperature variation. It shows that the elevated temperature results in the increase of contact angle and the decrease of bearing deformation, contact force and bearing stiffness, which result in the decrease of the natural frequencies of a HDD spindle system.

• Journal of Welding and Joining
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• 제21권6호
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• pp.55-63
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• 2003

Welded joint generally has heterogeneity of strength, material, and fracture toughness and it is important to understand the characteristics of material strength and fracture of welded joint considering heterogeneous effect. Characteristics of strength and fracture of an undermatched joint under dynamic loading was studied by round-bar tension tests and thermal elastic-plastic analyses in this paper. The strength and fracture of the undermatched joints should be evaluated based on the effects of the strain rate and the temperature including temperature rise during the dynamic loading. The differences of fracture characteristics like such as ductile-to-brittle transition behavior are well precisely explained from the stress-strain distribution obtained by numerical analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.860-864
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• 2001

Today's industrialized plants are required to reduce SOx emitted from stacks at factories, utility power stations, etc. For this purpose, flue gas desulfurization (FGD) system is installed and gas-gas heater (GGH) is used to play a vital role to reheat the wet treated gas from FGD. The sector plates are located at cold and hot sides of gas gas heater. They serve as sealing to prevent mixing treated and untreated gases. Therefore, the deformation of the sector plate due to its dead weight and gas pressure should be considered as major factor for the sector plate design.

• 한국소음진동공학회논문집
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• 제13권2호
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• pp.144-150
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• 2003

Pleasantness or quietness becomes one of the most important factors for residential and office building designs recently. Especially for apartments, the noise generated by falling objects becomes a sensitive issue these days. To overcome the problem of the impact noise in apartments, the floor design has been changed. To reduce the transmissibility of the noise. composite floor structures ate devised and implemented for the construction of apartments. In this paper. the noise reduction) performance of a composite floor plate with holes is analyzed. Computational models for the structures are developed and its Performance is evaluated by using the finite element method. The results show that the noise can be significantly reduced with the multi-layer composite floor plates with holes.

• Structural Engineering and Mechanics
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• 제53권6호
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• pp.1167-1182
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• 2015

In this study, the stresses and electric potential redistributions of a cylinder made from functionally graded piezoelectric material (FGPM) are investigated. All the mechanical, thermal and piezoelectric properties are modeled as power-law distribution of volume fraction. Using the coupled electro-thermo-mechanical relations, strain-displacement relations, Maxwell and equilibrium equations are obtained including the time dependent creep strains. Creep strains are time, temperature and stress dependent, the closed form solution cannot be found for this constitutive differential equation. A semi-analytical method in conjunction with the Mendelson method of successive approximation is therefore proposed for this analysis. Similar to the radial stress histories, electric potentials increase with time, because the latter is induced by the former during creep deformation of the cylinder, justifying industrial application of such a material as efficient actuators and sensors.