• Kyungpook Mathematical Journal
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• 제53권3호
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• pp.459-465
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• 2013

Let $p(z)$ be an analytic function defined on the open unit disk D and $p(0)=1$. Condition ${\beta}$ in terms of complex numbers D and real E with -1 < E < 1 and ${\mid}D{\mid}{\leq}1$ is determined such that $1+{\beta}{\prec}\frac{1+Dz}{1+Ez}$ implies $p(z){\prec}\sqrt{1+z}$. Furthermore, the expression $1+\frac{{\beta}zp^{\prime}(z)}{p(z)}$ and $1+\frac{{\beta}zp^{\prime}(z)}{p^2(z)}$ are considered in obtaining similar results.

• 대한수학회지
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• 제56권1호
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• pp.149-167
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• 2019

In this work, we study the existence, uniqueness and stability in the ${\alpha}$-norm of solutions for some stochastic partial functional integrodifferential equations. We suppose that the linear part has an analytic resolvent operator in the sense given in Grimmer [8] and the nonlinear part satisfies a $H{\ddot{o}}lder$ type condition with respect to the ${\alpha}$-norm associated to the linear part. Firstly, we study the existence of the mild solutions. Secondly, we study the exponential stability in pth moment (p > 2). Our results are illustrated by an example. This work extends many previous results on stochastic partial functional differential equations.

• Kyungpook Mathematical Journal
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• 제61권3호
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• pp.513-522
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• 2021

In this paper we investigate a subclass 𝓜(α) of the class of starlike functions in the unit disk |z| < 1. 𝓜(α), π/2 ≤ α < π, is the set of all analytic functions f in the unit disk |z| < 1 with the normalization f(0) = f'(0) - 1 = 0 that satisfy the condition $$1+\frac{{\alpha}-{\pi}}{2\;sin\;{\alpha}}. The class 𝓜(α) was introduced by Kargar et al. [Complex Anal. Oper. Theory 11: 1639-1649, 2017]. In this paper some basic geometric properties of the class 𝓜(α) are investigated. Among others things, coefficients estimates and bound are given for the Fekete-Szegö functional associated with the k-th root transform [f(z^k)]^1/k. Also a certain subclass of bi-starlike functions is introduced and the bounds for the initial coefficients are obtained.

• 호남수학학술지
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• 제44권4호
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• pp.521-534
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• 2022

In this paper, we introduce a new class 𝓡^k_λ(λ ≥ 1, k is any positive real number) of univalent complex functions, which consists of functions f of the form f(z) = z + Σ^∞_n=2 a_nzⁿ (|z| < 1) satisfying the subordination condition $$(1-{\lambda}){\frac{f(z)}{z}}+{\lambda}f^{\prime}(z){\prec}{\frac{1+r^2_kz^2}{1-k{\tau}_kz-{\tau}^2_kz^2}},\;{\tau}_k={\frac{k-{\sqrt{k^2+4}}}{2}$$, and investigate the Fekete-Szegö problem for the coefficients of f ∈ 𝓡^k_λ which are connected with k-Fibonacci numbers $F_{k,n}={\frac{(k-{\tau}_k)^n-{\tau}^n_k}{\sqrt{k^2+4}}}$ (n ∈ ℕ ∪ {0}). We obtain sharp upper bound for the Fekete-Szegö functional |a₃-𝜇a²₂| when 𝜇 ∈ ℝ. We also generalize our result for 𝜇 ∈ ℂ.

• 전자공학회논문지D
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• 제36D2호
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• pp.1-10
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• 1999

FET 소신호 모델의 직접추출법은 기생소자값을 구하기 위해 주로 순방향 소동(cold) FET 조건을 이용하고 있다. 본 논문은 수동 FET 조건에서 해석적 채널모델을 유도하고, 정상수동 소자 조건에서도 순방향 수동 FET 조건과 동일 한 정보를 얻을 수 이Tdmadmff 보인다. 이와 함께 수동 FET 조건에 의해 제한되는 능동 FET 소신호 모델의 오차를 추적하여 수동 FET 방법을 이용한 직접 추출 모델의 오차 한계를 살피고, 오차 최소점의 유무를 통해 수동 FET 기생저항값의 유효성을 검토한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1005-1011
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• 2007

The brake system of train must posses the large braking effort in order to stop the train safely within the limited traveling distance. But, the excessive braking effort has been deteriorated the ride comfort due to high level of deceleration and jerk, and sometimes occurred the skid, because the applied braking force exceeds the allowable adhesive force. This skid causes not only to increase the stopping distance but also to deteriorate the safety of train and damage the rail surface by wheel flat. In the present paper, the braking force for disc brake of Korea High Speed Train (HSR350x) was measured through on-line test and the adhesion force was estimated by using the analytic model in the skid condition. Also, we have discussed the relationship between the actual disc brake force and the adhesion force in real skid condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.628-633
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• 2003

An analysis on the steady-state has been made of flow of a compressible fluid rapidly-rotating in a pipe. The flow is induced by an small arbitrary azimuthally-varying thermal forcing added on the basic state of rigid body isothermal rotation. The system Ekman number is assumed to be very small value. Analytic solutions have been obtained for axisymmetric and non-axisymmetric types, in which the axisymmetric solution comes from the azimuthally-averaged wall boundary condition and the non-axisymmetric solution from fluctuating wall boundary condition.

• 대한전자공학회논문지
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• 제25권9호
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• pp.1108-1114
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• 1988

Usng the P.Yeh's analytic method, we derive the condition for oscillation of a linear phase conjugate oscillator which consists of photorefractive medium and two conventional mirrors. From this general oscillation condition, we obtain the threshold oscillation conditon of a single phase conjugate resonator and the self-oscillation condition of photorefractive medium, then in special case (phase shift =90\ulcorner: no external dc electric field), oscillation conditions of the linear phase conjugate oscillator for any cavity length are derived. The results indicate that, unlike in a phase conjugate oscillator with Kerr-like medium, oscillation cannot occur at special cavity length for given couplinyg strengths.

• 대한수학회보
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• 제30권1호
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• pp.29-34
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• 1993

J. Leray [7] proposed a sufficient condition ofr the solvability of the Cauchy problem on the initial hyperplane x$_{1}$=0 with Cauchy data which are holomorphic with respect to the variables parallel to some analytic subvariety S of the initial hyperplane. Limiting the problem to the case of operators with constant coefficients, A. Kaneko [2] proposed a new sharper sufficient condition. Later we generalized this condition and showed that it is necessary and sufficient for the solvability of the Cauchy problem for the hyperfunction Cauchy data and the distribution Cauchy data which contain variables parallel to S as holomorphic parameters in [5, 6]. In this paper, we extend the results in [6] to the case of operators with variable coefficients and show that it is sufficient for the solvability of the Cauchy problem for the hyperfunction Cauchy data. Our main theorem can be considered as an example of a deep theorem on micro-hyperbolic systems by Kashiwara-Schapira [4] and we give a direct proof based on an elementary sweeping out procedure developed in Kaneko [3].

• 한국터널지하공간학회 논문집
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• 제17권5호
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• pp.553-561
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• 2015

본 연구에서는 국내에 활발히 적용되기 시작한 쉴드 TBM 터널의 합리적인 유지관리를 위한 성능평가 기준을 제시하였다. 이를 위해 국내 외 성능평가 기준을 분석하였고, 국내 시공된 쉴드 TBM 터널에 대한 현장조사 및 정밀안전진단 보고서 분석을 통한 변상사례를 조사하여 성능평가 항목을 균열, 누수, 파손, 박리, 층분리 및 박락, 백태, 품질상태, 철근노출, 탄산화, 단차, 볼트상태, 배수상태, 지반상태, 접속부상태, 공동구 상태로 선정하였다. 또한 다중의사결정기법인 AHP 기법을 활용하여 선정된 성능평가에 대한 합리적인 가중치를 산정하였다.