• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.139-152
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• 2006

Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

• International Journal of Vascular Biomedical Engineering
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• v.2 no.1
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• pp.17-24
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• 2004

Tumor angiogenesis was simulated using a two-dimensional computational model. The equation that governed angiogenesis comprised a tumor angiogenesis factor (TAF) conservation equation in time and space, which was solved numerically using the Galerkin finite element method. The time derivative in the equation was approximated by a forward Euler scheme. A stochastic process model was used to simulate vessel formation and vessel elongation towards a paracrine site, i.e., tumor-secreted basic fibroblast growth factor (bFGF). In this study, we assumed a two-dimensional model that represented a thin (1.0 mm) slice of the tumor. The growth of the tumor over time was modeled according to the dynamic value of bFGF secreted within the tumor. The data used for the model were based on a previously reported model of a brain tumor in which four distinct stages (namely multicellular spherical, first detectable lesion, diagnosis, and death of the virtual patient) were modeled. In our study, computation was not continued beyond the 'diagnosis' time point to avoid the computational complexity of analyzing numerous vascular branches. The numerical solutions revealed that no bFGF remained within the region in which vessels developed, owing to the uptake of bFGF by endothelial cells. Consequently, a sharp, declining gradient of bFGF existed near the surface of the tumor. The vascular architecture developed numerous branches close to the tumor surface (the brush-border effect). Asymmetrical tumor growth was associated with a greater degree of branching at the tumor surface.

• Journal of Energy Engineering
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• v.7 no.2
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• pp.202-208
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• 1998

As in the other industrial processes, a nuclear power plant involves a steam relieving process through which condensable steam is discharged and condensed in a subcooled pool. An analysis of steam discharge transients was carried out using the method of characteristics to determine the flow characteristics and dynamic loads of piping that are used for structural design of the piping and its supports. The analysis included not only the steam flow rate but also the flow rates of the air and water which originally exist in the pipe. The analytical model was developed for a uniform pipe with friction through which the flow was discharged into a suppression pool. Including the combinations of system elements such as reservoir, valve and branching pipe lines. The piping flow characteristics and dynamic loads were calculated by varying system pressure, pipe length, and submergence depth. It was found that the dynamic load, water clearing time and water clearing velocity at the water/air interface were dependent not only on the system pressure and temperature but also on the pipe length and submergence depth.

• Journal of Plant Biotechnology
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• v.36 no.3
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• pp.207-213
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• 2009

Starch serves not only as an energy source for plants, animals, and humans but also as an environmentally friendly alternative for fossil fuels. Progress in understanding of starch biosynthesis, and the isolation of many genes involved in this process have enabled the genetic modification of crops in a rational manner to produce novel starches with improved functionality. Starch is composed of two glucose polymers, amylose and amylopectin. The amylose and amylopectin ratio in starch affects its physical and physicochemical properties. Alteration in starch structure can be achieved by modifying genes encoding the enzymes responsible for starch biosynthesis and starch hydrolysis. Here, we describe recent findings concerning the starch modification in sweetpotato. Sweetpotato [Ipomoea batatas (L.) Lam] ranks seventh in annual production among food crops in the world as an important starch source. To develop transgenic sweetpotato plants with modifying starch composition, we constructed transformation vectors overexpressing granule bound starch synthase I and inhibiting amylopectin synthesis genes such as starch branching enzyme and isoamylase under the control of 35S promoter, respectively. Transformation of sweetpotato (cv. Yulmi) is in progress.

• Journal of KIISE
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• v.43 no.4
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• pp.419-429
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• 2016

Generating a 3D surface model from coronary artery segmentation helps to not only improve the rendering efficiency but also the diagnostic accuracy by providing physiological informations such as fractional flow reserve using computational fluid dynamics (CFD). This paper proposes a method to generate a triangular surface mesh using vessel structure information acquired with coronary artery segmentation. The marching cube algorithm is a typical method for generating a triangular surface mesh from a segmentation result as bit mask. But it is difficult for methods based on marching cube algorithm to express the lumen of thin, small and winding vessels because the algorithm only works in a three-dimensional (3D) discrete space. The proposed method generates a more accurate triangular surface mesh for each singular vessel using vessel centerlines, normal vectors and lumen diameters estimated during the process of coronary artery segmentation as the input. Then, the meshes that are overlapped due to branching are processed by mesh merging and merged into a coronary mesh.

• Korean Journal of Plant Resources
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• v.15 no.3
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• pp.285-292
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• 2002

This study was carried out to determine agronomic and genetic characteristics of the production process in tropical yams(Dioscorea atata L.). To make clear the possibility of cultivation of tropical yams in the Suwon area, the growth of the aboveground parts and the enlargement of tuber of Dioscorea alata, were investigated. The aboveground parts of the plants whose sprouted mother tuber were planted in late April were grown slowly until the 70-days after planting and grown rapidly after. from about 150-days after plantation, total length of vines slowly decreased due to the burning of the branch vines of lower modes. With regard to the branching progressed to 4th for the solo yam and to 6th for purple yam. The secondary branches tended to grow better. When the formation of daughter tubers was observed at the 50-days after planting, their enlargement was very slow. The rapid growth of tubers began at the 140-days and continued to the 190-days. General components such as protein, fiber, and lipid were higher in D. opposita rather than in D. alata. Hardness of D. alata was 2696.2 while that of D. opposita was 4946.9. Lightness of D. alata was 73.99, being higher than that of D. opposita.

• Korean Journal of Plant Resources
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• v.18 no.1
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• pp.78-84
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• 2005

Charactertistics of growth from graft induced three stock of red pepper cultivar were analysed. R-safe rootstock was more higher and vigorous than that of the Yeok kang, Konesian hot cultivar at seedling stage and had good characteristics for grafting in the space of cut surface and the amount of sap released. Numbers of branches were more numerous in the grafted plants than those of non-grafted as grafting affected their growths in the process of branching. There was no distinct difference in plant height among the different rootstock. However the R-safe rootstock showed considerably high growth in the 41st days after grafting. Grafting was effective in the early flowering and the R-safe was the earliest in flowering because of it's good growth under the low temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.393-393
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• 2010

The biocompatibility of materials used for biomedical applications depends on chemical composition, mechanical stiffness, surface energy, and roughness. The plasma treatment and etching process is a very important technology in the biomedical fields due to possibility of controlling the surface chemistry and properties of materials. In this work, $N_2/H_2$ plasma were treated on single-walled carbon nanotubes (SWCNTs) paper and characterization of treated SWCNTs paper was carried out. Also we investigated neurite outgrowth from SH-SY5Y on treated SWCNTs paper. The results indicated that $N_2/H_2$ plasma-modified SWCNTs paper enhanced neuronal cell adhesion, viability, neurite outgrowth and branching in vitro and exerted a positive role on the health of neural cells.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.71-77
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• 2019

This paper defines a multi-selection knapsack problem and presents an algorithm for seeking its optimal solution. Multi-selection means that all members of the particular group be selected or excluded. Our branch-and-bound algorithm introduces a simplex containing the feasible region of the original problem to exploit the fact that the most tightly underestimating function on the simplex is linear. In bounding operation, the subproblem defined over the candidate simplex is minimized. During the branching process the candidate simplex is splitted into two one-less dimensional subsimplices by being projected onto two hyperplanes. The approach of this paper can be applied to solving the global minimization problems under various types of the knapsack constraints.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.578-585
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• 2015

Track elastic components can be technically and economically efficient when integrated well into track superstructure of a railway network. In such cases, the elastic rail pad is larger than a 800m radius curve provides smooth rail branching and allows for high-speed operation ($V{\geq}160km/h$). High track resistance causes the tamping intervals to stand out because the constantly increasing share of the sleeper pad further extends the increase of the tamping interval and the long grinding period; the engineering and construction of the small curve radius track provides some measures for reducing the solid sounds. Installation of elastic mats under the ballast can have a good effect, particularly in the context of protection against dust during construction or extensive renovation measures when laying new lines. However, such a process requires special attention and proper installation.