• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.709-719
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• 2001

In particle or short-fiber reinforced composites, cracking of reinforcements is a significant damage mode because the cracked reinforcements lose carrying capacity. This paper deals with elastic stress distributions and load carrying capacity of intact and cracked ellipsoidal inhomogeneities. Three dimensional finite element analysis has been carried out on intact and cracked ellipsoidal inhomogeneities in an infinite body under uniaxial tension and pure shear. For the intact inhomogeneity, as well known as Eshelbys solution, the stress distribution is uniform in the inhomogeneity and nonuniform in the surrounding matrix. On the other hand, for the cracked inhomogeneity, the stress in the region near the crack surface is considerably released and the stress distribution becomes more complex. The average stress in the inhomogeneity represents its load carrying capacity, and the difference between the average stresses of the intact and cracked inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The load carrying capacity of the cracked inhomogeneity is expressed in to cracking damage. The load carrying capacity of the cracked inhomogeneity is expressed in terms of the average stress of the intact inhomogeneity and some coefficients. It is found that a cracked inhomogeneity with high aspect ratio still maintains higher load carrying capacity.

• Journal of the Korean institute of surface engineering
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• 제26권2호
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• pp.63-70
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• 1993

The mechanical properties of ferrite-martensited dual phases steels are affected by the microstructural factors, such as martensited volume fractions, ferrite grain size, strength ratio, connectivity, etc. Two phase alloys are technologically important. However, there is a lack of understanding as to stress-strain behavior of dual phase alloy in terms of stress-strain behavior of each component phases. The lack of the understanding stems from the complex deformation behavior of two phase alloys. The aim of this study is to rationalize stress-strain behavior of dual phase alloy in terms of the stress-strain behavior of component phase by systematically considering all the factors listed above. It was found that for a given martensite volume fraction, the calculated stress-strain curve was higher for a finer particles size than for a coarse particle sized within the range of the strains considered, and this behavior was seen for all the different volume fraction alloys considered. The calculated stress-strain curves were compared with corresponding experimental curves, and in general, good agreement was found. The maximum difference in flow stress between the calculated and the experimental results occurs at the nearly beginning of the plastic deformation.

• Journal of Integrative Natural Science
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• 제2권2호
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• pp.55-58
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• 2009

A ligand-receptor docking program is an indispensible tool in modern pharmaceutical design. An accurate prediction of small molecular docking pose to a receptor is essential in drug design as well as molecular recognition. An effective docking program requires the ability to locate a correct binding pose in a surprisingly complex conformational space. However, there is an inherent difficulty to predict correct binding pose. The odds are more demanding than finding a needle in a haystack. This mainly comes from the flexibility of both ligand and receptor. Because the searching space to consider is so vast, receptor rigidity has been often applied in docking programs. Even nowadays the receptor may not be considered to be fully flexible although there have been some progress in search algorithm. Improving the efficiency of searching algorithm is still in great demand to explore other applications areas with inherently flexible ligand and/or receptor. In addition to classical search algorithms such as molecular dynamics, Monte Carlo, genetic algorithm and simulated annealing, rather recent algorithms such as tabu search, stochastic tunneling, particle swarm optimizations were also found to be effective. A good search algorithm would require a good balance between exploration and exploitation. It would be a good strategy to combine algorithms already developed. This composite algorithms can be more effective than an individual search algorithms.

• Journal of the Microelectronics and Packaging Society
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• 제12권2호
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• pp.141-147
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• 2005

Nanomaterial $TiO_2-SiO_2$ was synthesized by hydrolysis and condensation process using 2-propanol(2-PrOH) and was characterized by FT-IR, DSC, XRD and FE-SEM. FT-IR spectra were measured to investigate Ti-0-Si absorption peak. DSC thermal analysis results appllied to Ozawa equation were used to calculate to activation energy of crystallization. It was found that the changes of X-ray diffraction patterns and FWHM obtained XRD measurement depended on calcination temperature. In FE-SEM analysis, particle size changed by quantity changes of Ti-alkokide.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.254-259
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• 2001

There are advantages in the installation of dual subsea pipelines over two separate single lines. In many case it can reduce the cost for trench, back-filling and installation. However the installation of dual pipelines often requires technical challenges. Dual Pipelines should be placed to be stable to external loading not only during the installation but also in the design life. Dual pipelines in trench can reduce the influence of external forces. To investigate applied forces as slope changes, number of experiments are conducted with PIV (Particle Image Velocimetry) in a circulating water channel. Numerical approaches are also made to compare with experimental results. The velocity fields around dual pipelines in trench are investigated and analysed. Comparison of both results show similar pattern of flow around dual pipelines. it is proved that the trench slope affects the pipeline stability significantly. The results can be applied in the stability design of dual pipelines in trench section. The complex flow patterns can be referenced effectively linked in the understanding of fluid around circular bodies in trench.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제9권5호
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• pp.480-485
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• 1999

The $SrTiO_3$ with Al, Pr red phosphor for FED was synthesized by Pechini process using metallic nitrates, ethylene glycol and citric acid. The different particle growth tendency of $SrTiO_3$ phosphor powder was observed at above and below $900^{\circ}C$. Also, luminescent properties were observed under 359 nm excitation of Pr ion. The emission band was shown between 575 nm and 650 nm with 617 nm maximum spectra. Therefore, $SrTiO_3$ with Al, Pr phosphor is applicable to red phosphor of FED.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.580-590
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• 2018

Active distribution system (ADS) considering distributed generation (DG) and electric vehicle (EV) is an effective way to cut carbon emission and improve system benefits. ADS is an evolving, complex and uncertain system, thus comprehensive model and effective optimization algorithms are needed. Battery swapping station (BSS) for EV service is an essential type of flexible load (FL). This paper establishes ADS planning model considering BSS firstly for the minimization of total cost including feeder investment, operation and maintenance, net loss and carbon tax. Meanwhile, immune binary firefly algorithm (IBFA) is proposed to optimize ADS planning. Firefly algorithm (FA) is a novel intelligent algorithm with simple structure and good convergence. By involving biological immune system into FA, IBFA adjusts antibody population scale to increase diversity and global search capability. To validate proposed algorithm, IBFA is compared with particle swarm optimization (PSO) algorithm on IEEE 39-bus system. The results prove that IBFA performs better than PSO in global search and convergence in ADS planning.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제23권7호
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• pp.918-927
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• 1999

In the fully developed internal flow fields, there are complex transition flows caused by interaction of the cross flow and jet when jet is Injected Into the flow. These interactions are studied by means of the flow visualization methods. An instantaneous laser tomographic method is used to reveal the physical mechanism and the structure of vortices formation in the branch pipe flow. The velocity range of cross flow of the pipe is 0.7m/s and the corresponding Reynolds number $R_{cf}$, based on the duct height is $5.6{\times}10^3$, diameter/height ratios(d/H) 0.14 and velocity ratios 3.0. Oil mist with the size of $10{\mu}m$ diameter is used for the scattering particle. The instantaneous topological features of the vortex ring roll-up of the jet shear layer and characteristics of this flow are studied in detail by performing flow visualization in rectangular duct flow. It is found that the formation and roll-up of ring vortices is a periodic phenomenon. The detailed topology of the vortices in the near field of a cross -flow jet and the mechanism associated with them give enforced hints of vortex breakdown within the vortex system due to the interaction of the jet and the cross-flow.

• Journal of Ship and Ocean Technology
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• 제6권2호
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• pp.12-22
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• 2002

Offshore pipelines play an important role in the transportation of gas, oil, water and oil products. It is common to have a group of pipelines in the oil and gas field. To reduce the installation cost and time, dual pipelines are designed. There are great advantages in the installation of dual pipelines over two separate single lines. It can greatly reduce the cost for trench, back-filling and installation. However the installation of dual pipelines often requires technical challenges. Pipelines should be placed to be stable against external loadings during installation and design life period. Dual pipelines in trench can reduce the influence of external forces. To investigate the flow patterns and forces as trench depth and slope changes, number of experiments are conducted with PIV(Particle Image Velocimetry) equipment in a Circulating Water Channel. Numerical approaches to simulate experimental conditions are also made to compare with experimental results. The velocity fields around dual pipelines in trench are investigated and analysed. Comparison of both results show similar patterns of flow around pipelines. It is proved that the trench depth contributes significantly on hydrodynamic stability. The trench slope also affects the pipeline stability. The results can be applied in the stability design of dual pipelines in trench section. The complex flow patterns can be effectively linked in the understanding of fluid motions around multi-circular bodies in trench.

• Applied Microscopy
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• 제28권4호
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• pp.527-538
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• 1998

This study was performed to investigate the activity of antibodies in the tissues of Paragonimus westermani at the different developmental stages. Enzyme-linked immunosorbent assay (ELISA) and Immunelectron microscopy (IEM) were applied, using the dog sera infected with metacercariae isolated from Cambaroides similis. These dog sera were obtained from 3rd to 96th week after infection by bleeding. The supernatants of homogenated worms for worm antigen were used. The worm tissues were embedded in Lowicryl HM 20 medium, treated with infected serum and protein A gold complex (particle size; 12 nm) and observed by electron microscope. In the pattern of antibody levels by ELISA test in all developemental worm antigens, the activity of antibody was very weak in the 3rd week, but strong in the worm antibody from 4th to 20th week after infection. Its activity was maintained even till 96th week. The antibody level of the L2th week worm antigen was higher than those of the 20th and 48th week worm antigens. Generally, many gold particles were observed on the secretory granules and the epithelial lamellae. Thus, it was concluded that the antigenic materials in the developmental worm tissues were especially concentrated on the secretory granules in the parenchymal tissues and the epithelial lamellae in the lumen of the caecum.