• 한국안전학회지
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• 제17권1호
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• pp.99-104
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• 2002

아크축(arch axis)의 연장(extensibility) 및 회전관성(rotatory inertia)을 고려한 곡선보(curved beam)의 평면내(in-plane) 자유진동을 미분구적법(DQM)을 이용하여 다양한 경계조건(boundary conditions)과 굽힘각(opening angles)에 따른 진동수(frequencies)를 계산하였다. DQM의 결과를 다른 수치해석결과와 비교하였으며, DQM은 적은 요소(grid points)을 사용하여 정확한 해석결과를 보여주었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.498-499
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• 2011

In this paper, the fundamental features of the arc stability DC arc furnace have been investigated, from the converter point of view. To compare of measurement arc data from DC arc furnace and the advanced arc simulations of magneto-hydrodynamics (MHD) and the well known Cassie-Mayr arc model have been extensively used. The MHD based arc simulation has been validated in the subcomponent level, for the free burning arc set up in the laboratory. The arc simulation predicted the arc voltage for different currents with the accuracy which satisfies engineering requirements. It has been shown that the arc current steepness at current zero determines the arc stability, and the associated peak arc resistance can be used as its quantitative measure. Based on the presented insight into the DC arc stability, a converter topology solution which realizes an optimal arc stability has been proposed. The main results presented in this paper provide a design guideline for the future DC arc furnace converter topology developments.

• 한국실내디자인학회논문집
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• 제13권4호
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• pp.56-65
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• 2004

Contemporary Architecture is showing many aspects on the ground of ecological paradigm, while, searching for a new architectural direction to make importance of environment that has been still little accounted of a subject of discussion. And 'sustainability'will become a central concept of a Contemporary architectural topic, continuously. With a demand of the time, ecological inclinations have been started to develop a collective low-rise housing project. It is going to expands several fields, but for reasons of social economic activity for human fundamental being, potentialities of basic problem solution are enough for ecologyㆍenvironment, but distinct direction and measures are still not obvious conditions. This study is for healing restoration in global environment, with architectural approach, through analyzing relation between ecological architectural space and nature, and abstracts various inter-relational aspect's specific character. the purpose of this study is another approach of intimate relation of ecological architecture and nature. Therefore, this study is significant to be on the search for a start to suggest a new point of view to ecological architectural space.

• 환경영향평가
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• 제12권5호
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• pp.323-340
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• 2003

There have been persistent civil appeals in Ansan area against the odor and aerosols emitted from nearby Banwol/Sihwa industrial complex. A fundamental solution for the good air quality has not been addressed yet in spite of the continuous counterplan to reduce odor emission. A systematic and scientific study is needed to examine the reason for the odor episode and to predict the impact coverage of odor pollution. An approach by computational simulation is considered to be adequate to investigate the transportation and the dispersion processes of air pollutants blown by sea breeze toward the coastal city, Ansan. This study has employed various dispersion models to simulate the transportation and the dispersion processes of odor pollutants by a local circulation between land/sea breeze using the data set of emission rates of odorous species from the Banwol/Sihwa industrial complex.

• 대한산업공학회지
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• 제30권3호
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• pp.190-196
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• 2004

In this paper, we address a layout design problem, PTL[3], for determining an optimal 3-class-based dedicated linear storage layout in a class of unit load storage systems. Our objective is to minimize the expected single command travel time. We analyze PTL[3] to derive a fundamental property that an optimal solution to PTL[3] is one of the partitions based on the PAI(product activity index)-nonincreasing ordering. Using the property and partial enumeration, we construct an efficient exact algorithm with O $(n\;{\lceil}\;log\;n\;{\rceil}\;)$ for solving PTL[3].

• 전기학회논문지
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• 제67권11호
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• pp.1434-1446
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• 2018

This paper presents new speed control strategy for periodic load torque injected in AC motor. If motor drive system has a periodic load torque, it causes a periodic motor speed ripple bringing about vibrations and noises. This paper proposed new control method consisting of PIR(proportional-integral-resonant) controller and repetitive controller. PIR controller controls DC, low frequency and fundamental components and repetitive controller controls other harmonics. The performance has been verified through computer simulations using MATLAB Simulink and experiments.

• Korean Journal of Mathematics
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• 제8권2호
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• pp.163-172
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• 2000

Let $\mathcal{S}^{\prime}(\mathbb{R})$ be the dual of the Schwartz spaces $\mathcal{S}(\mathbb{R})$), A be a self-adjoint operator in $L^2(\mathbb{R})$ and ${\Gamma}(A)^*$ be the adjoint operator of ${\Gamma}(A)$ which is the second quantization operator of A. It is proven that under a suitable condition on A there exists a nuclear subspace $\mathcal{S}$ of a fundamental space $\mathcal{S}_A$ of Hida's type on $\mathcal{S}^{\prime}(\mathbb{R})$) such that ${\Gamma}(A)\mathcal{S}{\subset}\mathcal{S}$ and $e^{-t{\Gamma}(A)}\mathcal{S}{\subset}\mathcal{S}$, which enables us to show that a stochastic differential equation: $$dX(t)=dW(t)-{\Gamma}(A)^*X(t)dt$$, arising from the central limit theorem for spatially extended neurons has an unique solution on the dual space $\mathcal{S}^{\prime}$ of $\mathcal{S}$.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.847-865
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• 2015

This paper presents the application of a recently developed meta-heuristic algorithm, called Colliding Bodies Optimization (CBO), for size and topology optimization of steel trusses. This method is based on the one-dimensional collisions between two bodies, where each agent solution is considered as a body. The performance of the proposed algorithm is investigated through four benchmark trusses for minimum weight with static and dynamic constraints. A comparison of the numerical results of the CBO with those of other available algorithms indicates that the proposed technique is capable of locating promising solutions using lesser or identical computational effort, with no need for internal parameter tuning.

• Smart Structures and Systems
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• 제25권4호
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• pp.501-514
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• 2020

This article presents a comprehensive model to investigate a free vibration and resonance frequencies of nanostructure perforated beam element as nano-resonator. Nano-scale size dependency of regular square perforated beam is considered by using nonlocal differential form of Eringen constitutive equation. Equivalent mass, inertia, bending and shear rigidities of perforated beam structure are developed. Kinematic displacement assumptions of both Timoshenko and Euler-Bernoulli are assumed to consider thick and thin beams, respectively. So, this model considers the effect of shear on natural frequencies of perforated nanobeams. Equations of motion for local and nonlocal elastic beam are derived. After that, analytical solutions of frequency equations are deduced as function of nonlocal and perforation parameters. The proposed model is validated and verified with previous works. Parametric studies are performed to illustrate the influence of a long-range atomic interaction, hole perforation size, number of rows of holes and boundary conditions on fundamental frequencies of perforated nanobeams. The proposed model is supportive in designing and production of nanobeam resonator used in nanoelectromechanical systems NEMS.

• 대한수학회지
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• 제47권2호
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• pp.425-443
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• 2010

We investigate the Schr$\ddot{o}$dinger type operator $H_2\;=\;(-\Delta_{\mathbb{H}^n})^2+V^2$ on the Heisenberg group $\mathbb{H}^n$, where $\Delta_{\mathbb{H}^n}$ is the sublaplacian and the nonnegative potential V belongs to the reverse H$\ddot{o}$lder class $B_q$ for $q\geq\frac{Q}{2}$, where Q is the homogeneous dimension of $\mathbb{H}^n$. We shall establish the estimates of the fundamental solution for the operator $H_2$ and obtain the $L^p$ estimates for the operator $\nabla^4_{\mathbb{H}^n}H^{-1}_2$, where $\nabla_{\mathbb{H}^n}$ is the gradient operator on $\mathbb{H}^n$.