• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.17-22
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• 1999

Convergence characteristics and efficiency of three implicit approximate factorization schemes(ADI, DDADI and MAF) are examined using 2-Dimensional compressible upwind Navier-Stokes code. Second-order CSCM(Conservative Supra Characteristic Method) upwind flux difference splitting method with Fromm scheme is used for the right-hand side residual evaluation, while generally first-order upwind differencing is used for the implicit operator on the left-hand side. Convergence studies are performed using an example of the flow past a NACA0012 airfoil at steady transonic flow condition, i. e. Mach number 0.8 at $1.25^{\circ}$ angle of attack. The results were compared with other computational results in order to validate the current numerical analysis. The results from the implicit AF algorithms were compared well in low surface with the other computational results; however, not well in upper surface. It might be due to lack of the grid around the shock position. Because the algorithm minimizes the errors of the approximate decomposition, the improved convergence rate with MAF were observed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.299-319
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• 1997

Since a convergence strategy in interactive procedure is the origin of a lot of the restrictions and inconvenience of many methods, a new flexible convergence strategy is necessary for developing that is applicable for interactive MOLP as well as interactive multiple objective integer programming(MOIP). A method for computing the volume of the interval defined subsets of weighting vector space is developed using Sobol's LP$_{i}$, Generator. Since the interactive procedure requires a number of iterations, with a fixed number of solutions presented per iteration, a convergence strategy is needed to control the rate at which the interactive procedure converges to a final solution. Thus, in this paper, a new convergency strategy is developed.

• Bulletin of the Korean Mathematical Society
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• v.39 no.4
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• pp.607-615
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• 2002

Let (X, $X_{n}$, n$\geq$1) be a sequence of i.i.d. random variables and { $a_{ni}$ , 1$\leq$i$\leq$n, n$\geq$1} be an array of constants. Let ø($\chi$) be a positive increasing function on (0, $\infty$) satisfying ø($\chi$) ↑ $\infty$ and ø(C$\chi$) = O(ø($\chi$)) for any C > 0. When EX = 0 and E[ø(｜X｜)]〈$\infty$, some conditions on ø and { $a_{ni}$ } are given under which (equation omitted).).

• Journal of Life Science
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• v.27 no.8
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• pp.879-887
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• 2017

It is well established that brain-derived neurotrophic factor (BDNF) is expressed not only in the brain but also in skeletal muscle, and is required for normal neuromuscular system function. Histone deacetylases (HDACs) and insulin-like growth factor-I (IGF-I) are potent regulators of skeletal muscle myogenesis and muscle gene expression, but the mechanisms of HDAC and IGF-I in skeletal muscle-derived BDNF expression have not been examined. In this study, we examined the effect of IGF-I and suberoylanilide hydroxamic acid (SAHA), a pan-HDAC inhibitor, on BDNF induction. Proliferating or differentiating C2C12 skeletal muscle cells were treated with increasing concentrations (0-50 ng/ml) of IGF-I in the absence or presence of $5{\mu}M$ SAHA for various time periods (3-24 hr). Treatment of C2C12 cells with IGF-I resulted in a dose- and time-dependent decrease in BDNF mRNA expression. However, inhibition of HDAC led to a significant increase in the expression of BDNF mRNA levels. In addition, immunocytochemistry revealed high BDNF protein levels in undifferentiated C2C12 skeletal muscle cells, whether untreated, IGF-I-treated, or exposed to SAHA. These results represent the first evidence that IGF-I can suppress the mRNA and protein expression of BDNF; conversely, SAHA attenuates the effects of IGF-I. Consequently, SAHA upregulates BDNF expression in C2C12 skeletal muscle cells.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.407-410
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• 2004

There have been numberous structure-related accidents including structural destruction from past to the present. This experiment used a beachmark technique that does not exceed the maximum stress and reduce the range of amplitude(or alternating stress).Difference in stress on the actual section affects the progress of crack.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.617-625
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• 2018

Phishing website has become a crucial concern in cyber security applications. It is performed by fraudulently deceiving users with the aim of obtaining their sensitive information such as bank account information, credit card, username, and password. The threat has led to huge losses to online retailers, e-business platform, financial institutions, and to name but a few. One way to build anti-phishing detection mechanism is to construct classification algorithm based on machine learning techniques. The objective of this paper is to compare different classifier ensemble approaches, i.e. random forest, rotation forest, gradient boosted machine, and extreme gradient boosting against single classifiers, i.e. decision tree, classification and regression tree, and credal decision tree in the case of website phishing. Area under ROC curve (AUC) is employed as a performance metric, whilst statistical tests are used as baseline indicator of significance evaluation among classifiers. The paper contributes the existing literature on making a benchmark of classifier ensembles for web phishing detection.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.3
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• pp.171-177
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• 2007

It is well known that mobile phones have been a indispensable communication tool for human life. The spiral springs are used as the main component of the semi-auto sliding mechanism of mobile phones. The characteristic of axiomatic approach is scientific and analytical method, and axiomatic approach is different from other design methods in offering the systematic method at an early stage of design. The axiomatic approach could determine design parameter and arrange the order of design and estimate the optimum design in good order. In axiomatic approach, the composition is divided by customer requirement, functional requirement, design parameter, and design matrix in large portion. This paper presents design in sliding mechanism for mobile phones by finite element method and axiomatic design.

• Bulletin of the Korean Mathematical Society
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• v.48 no.2
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• pp.303-314
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• 2011

For Ax = b, it has recently been reported that the convergence of the preconditioned Gauss-Seidel iterative method which uses a matrix of the type P = I + S (${\alpha}$) to perform certain elementary row operations on is faster than the basic Gauss-Seidel method. In this paper, we discuss the adaptive Gauss-Seidel iterative method which uses P = I + S (${\alpha}$) + $\bar{K}({\beta})$ as a preconditioner. We present some comparison theorems, which show the rate of convergence of the new method is faster than the basic method and the method in [7] theoretically. Numerical examples show the effectiveness of our algorithm.

• Journal of computational fluids engineering
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• v.9 no.3
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• pp.26-38
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• 2004

A study has been made for the investigation of the robustness and convergence of various implicit operators of the LU-SGS scheme using linear stability analysis. It is shown that the behavior of the implicit operator is not determined by its own characteristics, but is determined relatively depending on the dissipative property of the explicit operator. It is also shown that, as the dissipation level of the implicit operator increases, the robustness of the scheme increases, but the convergence rate can be deteriorated due to the excessive dissipation. The numerical results demonstrate that the dissipation level of the impliict operator needs to be higher than that of the explicit operator for computing stiff problems.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.3
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• pp.219-224
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• 2002

We consider the problem y"=a(x,y)(y-b), y(0)=0, y'(1)=g(y(${\xi}$), y'(${\xi}$)), (0${\xi}$ fixed in(0,1)) as a model of steady-slate heat conduction in a rod when the heat flux at the end x = 1 is determined by observation of the temperature and heat flux at some interior point ${\xi}$. We establish conditions sufficient for existence, uniqueness.