• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.4
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• pp.383-389
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• 2011

In this paper, a statistical calibration method is proposed in order to identify the variability of complex modulus for a rubber material due to operational temperature and experimental/model errors. To describe temperature- and frequency-dependent material properties, a fractional derivative model and a shift factor relationship are used. A likelihood function is defined as a product of the probability density functions where experimental values lie on the model. The variation of the fractional derivative model parameters is obtained by maximizing the likelihood function. Using the proposed method, the variability of a synthetic rubber material is estimated and applied to a rubber mount problem. The dynamic characteristics of the rubber mount are calculated using a finite element model of which material properties are sampled from Monte Carlo simulation. The calculated dynamic stiffnesses show very large variation.

• Journal of the Korean Ceramic Society
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• v.56 no.1
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• pp.98-103
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• 2019

Optical filters to control light wavelength of displays or cameras are fabricated by multi-layer stacking process of low and high index thin films. The process of multi-layer stacking of thin films has received much attention as an optimal process for effective manufacturing in the optical filter industry. However, multi-layer processing has disadvantages of complicated thin film process, and difficulty of precise control of film morphology and material selection, all of which are critical for transmittance and coloring effect on filters. In this study, the composite $TiO_2$, which can be used to control of UV absorption, coated on nano hollow silica sol, was synthesized as a coating material for optical filters. Furthermore, systematic analysis of the process parameters during the chemical reaction, and of the structural properties of the coating solutions was performed using SEM, TEM, XRD and photo spectrometry. From the structural analysis, we found that the 85 nm nano hollow silica with 2.5 nm $TiO_2$ shell formation was successfully synthesized at proper pH control and titanium butoxide content. Photo luminescence characteristics, excited by UV irradiation, show that stable absorption of 350 nm-light, correlated with a 3.54 eV band gap, existed for the $TiO_2$ shell-nano hollow silica reacted with 8.8 mole titanium butoxide solution. Transmittance observed on substrate of the $TiO_2$ shell-nano hollow silica showed effective absorption of 200-300 nm UV light without deterioration of visible light transparency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.1
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• pp.81-87
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• 2012

This paper establishes a modeling and simulation procedure for structural response and reliability of a cylindrical array sensor on submarines under the shock generated by underwater explosion. The structural reliability of SONAR is important because the submarine could get out of combat ability by the structural damage of the SONAR upon explosion. A cylindrical array sensor was first modeled using the finite element method. Modal analysis was then performed for the check of the reliability of the modeling. The shock resistance simulations were performed for the responses to the structural shock waves and for the responses to the directly applied underwater shock waves, according to BV-043 and MIL-STD-901D, respectively. The stresses of the structure were evaluated with von-Mises scheme. Vulnerable regions were exposed through mapping the maximum stress to the structural model. Maximum stress of the SONAR was compared with the yield stress of the material to examine the structural reliability.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.199-205
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• 2006

The composite frame system with reinforced concrete column and steel beam can be improved in its structural efficiency by complementing the shortcomings of the two systems. The system, however, has many inherent problems in practical design and construction process due to the dissimilarities of the materials. Considering these circumstance, this research aims for the development of a composite structural system which connects the steel beams to the R/C columns with higher structural safety and economy. Basically, the proposed connection system is composed of four split tees, structural angles reinforced by a stiffener, high strength steel rods, connecting plates and shear plates. Structural tests have been carried out to investigate the moment transfer mechanism 1Tom the beam flange to steel rods or connecting plates through the structural angle reinforced by a stiffener. The four prototype specimens have been tested until the flange of the beam reached a plastic state. The test results indicated that no distinct material dissimilarities between concrete and steel have been detected for the proposed hybrid beam-column connection system and that the stress transfer through the structural angle between the beam flange and steel rods or connecting plates was very encouraging.

• Structural Engineering and Mechanics
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• v.39 no.4
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• pp.599-620
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• 2011

The investigation on possible causes of failures related to documented collapses is a complicated issue, primarily due to the scarcity and inadequacy of information available. Although several studies have tried to understand which are the inherent structural deficiencies or circumstances associated to failure of the main structural elements in a reinforced concrete frame, to the authors knowledge a uniform approach for the evaluation building static vulnerability, does not exist yet. This paper investigates, by means of a detailed case study, the potential failure mechanisms of an existing reinforced concrete building. The linear elastic analysis for the three-dimensional building model gives an insight on the working conditions of the structural elements, demonstrating the relevance of a number of structural faults that could sensibly lower the structure's safety margin. Next, the building's bearing capacity is studied by means of parametric nonlinear analysis performed at the element's level. It is seen that, depending on material properties, concrete strength and steel yield stress, the failure hierarchy could be dominated by either brittle or ductile mechanisms.

• Journal of Drive and Control
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• v.20 no.1
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• pp.1-7
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• 2023

In this study, the structural stability of the tank room of an aircraft rescue fire engine is to be studied. The tank room of the aircraft rescue fire engine is filled with fire extinguishing water and chemicals. Fire extinguishing water and chemical are filled to a capacity of about 12.5 tons and are subjected to high stress. The tank room is made of PP material with low yield stress. Structural analysis of the tank room is performed and structural weakness is analyzed. In addition, if a structural problem occurs as a result of structural analysis, an analysis simulation result is presented to derive an improved design and to show the validity of the structural stability of the tank room.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.241-246
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• 2008

Design of a high-speed railway line requires collaboration of heterogeneous application systems and of engineers with different background. Object-based 3D models with metadata can be a shared information model for the effective collaborative design. In this paper, railway infrastructure information model is proposed to enable integrated and inter-operable works throughout the life-cycle of the railway infrastructures, from planning to maintenance. In order to develop the model, object-based 3-D models were built for a 10km railway among Korea high-speed railway lines. The model has basically three information layers for designers, contractors and an owner, respectively. Prestressed concrete box-girders are the most common superstructure of bridges. The design information layer has metadata on requirements, design codes, geometry, analysis and so on. The construction layer has data on drawings, real data for material and products, schedules and so on. The maintenance layer for the owner has the final geometry, material data, products and their suppliers and so on. These information has its own data architecture which is derived from similar concept of product breakdown structure(PBS) and work breakdown structure(WBS). The constructed RIIM for the infrastructures of the high-speed railway was successfully applied to various areas such as design check, structural analysis, automated estimation, construction simulation, virtual viewing, and digital mock-up. The integrated information model can realize virtual construction system for railway lines and dramatically increase the productivity of the whole engineering process.

• Journal of the Korea Furniture Society
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• v.20 no.4
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• pp.339-357
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• 2009

Probability based design(PBD) method is independent of construction materials and uses real material properties unlike allowable stress design(ASD) that depends on small clear specimen property, also give quantitative safety and endurance lifetime of a certain material. Moreover, almost advanced country accepted PBD method instead of ASD method. So it is urgent to convert the current ASD method into the PBD method. However, there are wholly lacking of domestic researches related to current issue, and to solve several points in ASD method and to take advantage of PBD method, the conversion from the ASD method into the PBD method is a worldwide trend. Other domestic construction codes, such as steel or concrete constructions, accept the PBD method as well. Accordingly, to introduce PBD method into wood structural design, general theory, and preliminary data and methods were reviewed. With keeping this in mind, some important contents were reviewed, sorted some points for wood structural design that have distinctions against the other construction materials. Furthermore, the history of PBD method, and statistical data and theories for the PBD method, and preliminary data of resistance and load that are two random variables for the PBD method, and finally the difference between limit state design(LSD) and load and resistance factor design(LRFD) that were two superpowers in the PBD method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.60-63
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• 2000

The $0.94MgTiO_3-0.06SrTiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and DT-TGA. According to the X-ray diffraction patterns of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics, the cubic $SrTiO_3$ and hexagonal $MgTiO_3$ structures were coexisted. Increasing the sintering temperature from $1325^{\circ}C$ to $1400^{\circ}C$, average grain size was increased from $5.026{\mu}m$ to $8.377{\mu}m$. In the case of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics sintered at $1325^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 21.66, 2,522(at 7.34GHz), $+71ppm/^{\circ}C$, respectively.

• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.86-90
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• 2011

The mining of imitated manganese noodles in 1000 m of seawater is planned for 2012. Thus, it is necessary to prepare the lifting pipes to be used for the test. Because of storage and expense constraints, flexible and economic HDPE pipe is being considered, making it necessary to test the structural safety. Material, pressure-chamber tests and finite element analysis of HDPE pipe for the 1000-m depth were performed. The tangential stiffness of HDPE was obtained through tension and three-point bending material tests and used for a structural analysis. FEA results show that the current sample pipe segment is safe for 1000 m of water pressure, and the stress result is also within the safe value. From the current results, the HDPE pipe seems to be acceptable only for the currently suggested constraints. However, more numerical and pressure tests need to be considered by applying additional physical conditions such as gravitational and hydrodynamic loads, external and internal fluid pressure, axial force induced ship motion, and heavy pump pressure to determine future usage.