• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.959-977
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• 2022

The topological indices are numerical parameters which determined the biological, physical and chemical properties based on the structure of the chemical compounds. One of the recently topological indices is the uphill Zagreb indices. In this paper, the formulae of some uphill Zagreb indices for a few graph operations of some graphs have been derived. Furthermore, the precise formulae of those indices for the honeycomb network have been found along with their graphical profiles.

• 한국연소학회:학술대회논문집
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• 1998.10a
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• pp.155-164
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• 1998

Numerical analysis was performed with multicomponent transport properties and detailed reaction mechanisms for axisymetric 2-D CH4 jet diffusion, partial premixed, premixed flame. Calculations were carried out twice with C2-Full Mechanism including prompt NO reaction in addition to the above C2-Thermal NO Mechanism. The role of thermal NO mechanism and prompt NO mechanism on each flame's NO production is investigated by using the numerical result. The NOx production of each flame were evaluated Quantitatively in terms of the NOx emission index

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.205-214
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• 2007

Over the years, there has been increasing interest in solving mathematical problems with the aid of computers. The main purpose of this paper is to investigate the roots of the q-Bernoulli polynomials $B_{n,q}{^r}(x)$ for values of the index n by using computer. Finally, we consider the reflection symmetries of the q-Bernoulli polynomials $B_{n,q}{^r}(x)$.

• Communications of the Korean Mathematical Society
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• v.23 no.1
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• pp.141-151
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• 2008

In this paper, we derive the nonlinear equation for European option pricing containing liquidity risk which can be defined as the inverse of the partial derivative of the underlying asset price with respect to the amount of assets traded in the efficient market. Numerical solutions are obtained by using finite element method and compared with option prices of KOSPI200 Stock Index. These prices computed with liquidity risk are considered more realistic than the prices of Black-Scholes model without liquidity risk.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2032-2041
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• 2004

Results from an experimental study of flow distribution in a close-coupled catalytic converter(CCC) are presented. The experiments were carried out with a flow measurement system specially designed for this study under steady and transient flow conditions. A pitot tube was a tool for measuring flow distribution at the exit of the first monolith. The flow distribution of the CCC was also measured by LDV system and flow visualization. Results from numerical analysis are also presented. Experimental results showed that the flow uniformity index decreases as flow Reynolds number increases. In steady flow conditions, the flow through each exhaust pipe made some flow concentrations on a specific region of the CCC inlet. The transient test results showed that the flow through each exhaust pipe in the engine firing order, interacted with each other to ensure that the flow distribution was uniform. The results of numerical analysis were qualitatively accepted with experimental results. They supported and helped explain the flow in the entry region of CCC.

• Computers and Concrete
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• v.9 no.3
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• pp.171-178
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• 2012

This paper presents numerical studies of stiff fiber pullout behaviors of fiber reinforced cementitious composites based on a progressive damage model. The ongoing debonding process is simulated. Interfacial stress distribution for different load levels is analyzed. A parametric study, including bond strength and the homogeneity index on the pullout behaviors is carried out. The numerical results indicate that the bond stress decreases gradually from loaded end to embedded end along fiber-cement interface. The debonding initially starts from loaded end and propagates to embedded end as load increasing. The embedded length and bond strength affect the load-loaded end displacement curves significantly. The numerical results have a general agreement with the experimental investigation.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.150-155
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• 2003

Fractures in the form of micro cracks are commonly found in natural rocks. A rock behaves in a complex way due to fracture; in particular, the anisotropic strength of a rock material is significantly influenced by the presence of these fractures. Therefore, it is essential to understand the failure mechanism of a fractured rock. In this study, a fractured rock is formulated in terms of fabric tensor based on geometric and mechanical simplifications. In this way, position, density and shape of fractures can be determined by the fabric tensor so that rocks containing multi-fractures can successfully be modeled. Also an index to evaluate the degree of anisotropy of a fractured rock is proposed. Hence, anisotropic strength of a rock containing fractures under uniaxial compression condition is estimated through a series of numerical analyses for the multi-fractured model. Numerical investigations are carried out by varying the fracture angle from $0^{\circ}\;to\;90^{\circ}$ and relationship between uniaxial compression strength and the degree of anisotropy is investigated. By comparing anisotropic strength of numerical analysis with analytic solution, this study attempts to understand the failure mechanism of rock containing fractures.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.5-10
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• 2015

Femtosecond laser machining has been applied for creating a sensor function in silica glass optical fibers. Femtosecond laser pulses make it possible to fabricate micro structures in processed regions of a very thin glass fiber line because femtosecond laser pulses can extremely minimize thermal effects. With the laser machining to optical fiber using a single shot of 210-fs laser at a wavelength of 800 nm, it was observed that a processed region surrounded a thin layer which seemed to be a hollow cavity monitored by scanning electron microscopy (SEM). This study aims at a theoretical investigation for the processed region by using a numerical analysis in order to embed sensing function to optical fibers. Numerical methods based finite element method (FEM) has been used for an optical waveguide modeling. This report suggests two types modeling and describes a comparative study on optical losses obtained by the experiment and the numerical analysis.

• Geomechanics and Engineering
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• v.21 no.2
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• pp.143-152
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• 2020

Korean society experienced successive earthquakes exceeding 5.0 magnitude in the past three years resulting in an increasing concern about earthquake stability of urban infrastructures. This study focuses on the significant aspects of earthquake risk assessment for the cut-and-cover underground railway station based on two-dimensional dynamic numerical analysis. Presented are features from a case study performed for the railway station in Seoul, South Korea. The PLAXIS2D was employed for numerical simulation and input of the earthquake ground motion was chosen from Pohang earthquake records (M5.4). The paper shows key aspects of earthquake risk for soil-structure system varying important parameters including embedded depth, supported ground information, and applied seismicity level, and then draws several meaningful conclusions from the analysis results such as seismic risk assessment.

• Elastomers and Composites
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• v.55 no.4
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• pp.329-338
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• 2020

In this study, three different die geometries were selected to understand the die characteristics in the film casting extrusion processes. First, large and small-scale T-dies were numerically simulated to observe the scaled-down effect on the flow inside the dies. Second, three different dies-keyhole, linear tapper coat-hanger die (LTCD), and curved tapper coat-hanger die (CTCD)-were numerically observed and discussed according to the mass flow rate. Finally, the die exit velocity profiles and die characteristics were observed and discussed based on the power-law index for the LTCD die. These numerical simulations and numerical data will aid the optimization of the die design in industrial fields.