• 대한수학회보
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• 제57권5호
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• pp.1259-1267
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• 2020

On the periodicity of transcendental entire functions, Yang's Conjecture is proposed in [6, 13]. In the paper, we mainly consider and obtain partial results on a general version of Yang's Conjecture, namely, if f(z)ⁿf^(k)(z) is a periodic function, then f(z) is also a periodic function. We also prove that if f(z)ⁿ+f^(k)(z) is a periodic function with additional assumptions, then f(z) is also a periodic function, where n, k are positive integers.

• Korean Journal of Mathematics
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• 제22권3호
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• pp.529-552
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• 2014

As we know, some indices and data are strong influence to the price movement of some assets now, but not to another assets and in future. Thus we define some asset models for several time intervals; intraday, weekly, monthly, and yearly asset models. We define these asset models by using Brownian motion with volatility and Poisson process, and several deterministic functions(index function, twitter data function and big-jump simple function etc). In our asset models, these deterministic functions are the positive or negative levels of auxiliary indices, of analyzed data, and for imminent and extreme state(for example, financial shock or the highest popularity in the market). These functions determined by indices, twitter data and shocking news are a kind of one of speciality of our asset models. For reasonableness of our asset models, we introduce several real data, figurers and tables, and simulations. Perhaps from our asset models, for short-term or long-term investment, we can classify and reference many kinds of usual auxiliary indices, information and data.

• 한국생활과학회지
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• 제16권2호
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• pp.251-257
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• 2007

The combined impact of maternal depression, parenting stress, infant cry, and infant temperament on family functions was examined. The sample included 257 mothers in the near communities. Questionnaires completed by the mothers who had 0-36 month old children were used to measure depressive symptoms in mothers, infant cry, infant temperament, parenting stress, and family function. Maternal depression, parenting stress, infant crying and infant temperament had negative influence on family adaptability and family cohesion. Mother's depression had negative effect particularly on infant cry. Infant cry had positive effect on infant temperament. Infant temperament had high direct effect on parenting stress. As a result, it had negative influence on family function.

• 대한수학회보
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• 제46권6호
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• pp.1079-1089
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• 2009

In this paper, we shall show that for any entire function f, the function of the form $f^m(f^n$ - 1)f' has no non-zero finite Picard value for all positive integers m, n ${\in}\;{\mathbb{N}}$ possibly except for the special case m = n = 1. Furthermore, we shall also show that for any two nonconstant meromorphic functions f and g, if $f^m(f^n$-1)f' and $g^m(g^n$-1)g' share the value 1 weakly, then f $\equiv$ g provided that m and n satisfy some conditions. In particular, if f and g are entire, then the restrictions on m and n could be greatly reduced.

• Journal of applied mathematics & informatics
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• 제13권1_2호
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• pp.183-194
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• 2003

We will explain a new method for obtaining the nearly optimal domain for optimal shape design problems associated with the solution of a nonlinear wave equation. Taking into account the boundary and terminal conditions of the system, a new approach is applied to determine the optimal domain and its related optimal control function with respect to the integral performance criteria, by use of positive Radon measures. The approach, say shape-measure, consists of two steps; first for a fixed domain, the optimal control will be identified by the use of measures. This function and the optimal value of the objective function depend on the geometrical variables of the domain. In the second step, based on the results of the previous one and by applying some convenient optimization techniques, the optimal domain and its related optimal control function will be identified at the same time. The existence of the optimal solution is considered and a numerical example is also given.

• 대한수학회보
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• 제51권5호
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• pp.1425-1432
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• 2014

The Euler zeta function is defined by ${\zeta}_E(s)=\sum_{n=1}^{\infty}\frac{(-1)^{n-1}}{n^8}$. The purpose of this paper is to find formulas of the Euler zeta function's values. In this paper, for $s{\in}\mathbb{N}$ we find the recurrence formula of ${\zeta}_E(2s)$ using the Fourier series. Also we find the recurrence formula of $\sum_{n=1}^{\infty}\frac{(-1)^{n-1}}{(2_{n-1})^{2s-1}}$, where $s{\geq}2({\in}\mathbb{N})$.

• Applied Science and Convergence Technology
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• 제25권6호
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• pp.128-132
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• 2016

We investigated the effect of Ar ion sputtering on the surface electronic structure of indium tin oxide (ITO) using X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) measurements with increasing Ar ion sputtering time. XPS measurements revealed that surface contamination on ITO was rapidly removed by Ar ion sputtering for 10 s. UPS measurements showed that the work function of ITO increased by 0.2 eV after Ar ion sputtering for 10 s. This increase in work function was attributed to the removal of surface contamination, which formed a positive interface dipole relative to the ITO substrate. However, further Ar ion sputtering did not change the work function of ITO although the surface stoichiometry of ITO did change. Therefore, removing the surface contamination is critical for increasing the work function of ITO, and Ar ion sputtering for a short time (about 10 s) can efficiently remove surface contamination.

• 한국산업정보학회논문지
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• 제7권1호
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• pp.58-65
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• 2002

정수계획법모형에서 목적함수와 선형 제약조건식에 만족하는 최적해를 유도할 때, 선형 제약조건식으로 이루어지는 모든 가능해의 Convex set K에서 정수인 extreme point 또는 수정된 정수인 extreme point를 유도하여 목적함수Z의 최적해로 결정한다. 본 논문에서는 기저변수 벡터 $X_{B}$의 성분이 정수가 아닐 때 Branch & Bound 방법을 확장하여 $X_{B}$가 정수가 되도록 한다. 그리고 목적함수의 계수 $C_{j}$의 변동에 의하여 단계적으로 변하는 최적화를 유도함을 목적으로 한다. 한다.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1662-1669
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• 2006

Since randomness and uncertainties of design parameters are inherent, the robust design has gained an ever increasing importance in mechanical engineering. The robustness is assessed by the measure of performance variability around mean value, which is called as standard deviation. Hence, constraints in robust optimization problem can be approached as probability constraints in reliability based optimization. Then, the FOSM (first order second moment) method or the AFOSM (advanced first order second moment) method can be used to calculate the mean values and the standard deviations of functions describing constraints and object. Among two methods, AFOSM method has some advantage over FOSM method in evaluation of probability. Nevertheless, it is difficult to obtain the mean value and the standard deviation of objective function using AFOSM method, because it requires that the mean value of function is always positive. This paper presented a special technique to overcome this weakness of AFOSM method. The mean value and the standard deviation of objective function by the proposed method are reliable as shown in examples compared with results by FOSM method.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.157-164
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• 2000

This paper discusses the error propagation characteristics of the Newmark explicit method, modified Newmark explicit method and ${\alpha}$-function dissipative explicit method in pseudodynamic tests. The Newmark explicit method is non-dissipative while the ${\alpha}$-function dissipative explicit method and the modified Newmark explicit method are dissipative and can eliminate the spurious participation of high frequency responses. In addition, error propagation analysis shows that the modified Newmark explicit method and the ${\alpha}$-function dissipative explicit method possess much better error propagation properties when compared to the Newmark explicit method. The major disadvantages of the modified Newmark explicit method are the positive lower stability limit and undesired numerical dissipation. Thus, the ${\alpha}$-function dissipative explicit method might be the most appropriate explicit pseudodynamic algorithm.