• Kyungpook Mathematical Journal
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• 제50권4호
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• pp.537-543
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• 2010

Let X be a regular $T_1$-space such that each single point set is a $G_{\delta}$ set. Denot 'hereditarily closure-preserving' by 'HCP'. To consider a question of closed maps of S. Lin in [6], we improve some results of Foged in [1], and prove the following propositions. Proposition 1. $D\;=\;\{x{\in}X\;:\;\mid\{F{\in}\cal{F}:x{\in}F\}\mid{\geq}{\aleph}_0\}$ is discrete and closed if $\cal{F}$ is a collection of HCP. Proposition 2. $\cal{H}\;=\;\{{\cup}\cal{F}'\;:\;F'$ is an fininte subcolletion of $\cal{F}_n\}$ is HCP if $\cal{F}$ is a collection of HCP. Proposition 3. Let (X,$\tau$) have a $\sigma$-HCP k-network. Then (X,$\tau$) has a $\sigma$-HCP k-network F = ${\cup}_n\cal{F}_n$ such that such tat: (i) $\cal{F}_n\;\subset\;\cal{F}_{n+1}$, (ii) $D_n\;=\;\{x{\in}X\;:\;\mid\{F{\in}\cal{F}_n\;:\;x{\in}F\}\mid\;{\geq}\;{\aleph}_0\}$ is a discrete closed set and (iii) each $\cal{F}_n$ is closed to finite intersections.

• 한국전자파학회논문지
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• 제16권4호
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• pp.418-426
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• 2005

본 논문에저는 MoM 행렬 요소의 해석적 계산이 가능한 새로운 형태의 closed-form 그린함수 유도를 위한 최적의 근사화 경로 선택을 3-단계 근사화 방법 및 SDP(Steepest Descent Path) 방법을 고려하여 제시하였다. 본 논문의 방법으로 유도된 새로운 형태의 closed-form그린함수 계산 결과가 기존의 방법과 달리 파수 영역 그린함수의 사전조사 없이도 넓은 주파수 범위에서 보다 정확한 결과를 주고 있음을 알 수 있었다. 본 논문이 제안하는 방법의 타당성을 확인하기 위하여 몇 가지 수치 결과들을 제시하였다.

• Earthquakes and Structures
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• 제27권2호
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• pp.97-111
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• 2024

In this paper, buckling conditions and retrofitting of cylindrical steel water storage tanks with different roof types and wall thicknesses were investigated by using finite element method. Four roof types of cylindrical steel tanks which are open-top, flat-closed, conical-closed and torispherical-closed and three wall thicknesses of 4, 6 and 8 mm were considered in FE modeling of cylindrical steel tanks. The roof shapes significantly affect load distribution on the tank shell under the seismic action. Composite FRP materials are widely used for winding thin-walled cylindrical steel structures. The retrofitting efficiency of cylindrical steel water tank is tested under the seismic loading with the externally bonded CFRP laminates. In retrofitting of cylindrical steel tank, the CFRP composite material coating method was used to improve of seismic performance of cylindrical steel tanks. ANSYS software was used to analyze the cylindrical steel tanks and maximum equivalent (von-Mises) and directional deformation were obtained. Equivalent (von-Mises) stresses significantly decreased due to the coating of the tank shell with FRP composite material. In thin-walled steel structures, excessive stress causes buckling and deformations. Therefore, retrofitting led to decrease in stress, reductions in directional and buckling deformation of the open-top, flat-closed, conical-closed and torispherical-closed tanks.

• 대한치과보철학회지
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• 제54권1호
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• pp.35-40
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• 2016

상악골 결손은 악안면 부위의 해부학적 기형과 기능 장애를 초래한다. 기능적 측면에서, 상악골 결손은 발음, 저작, 연하 장애를 일으킬 수 있다. 상악절제술을 받은 환자에게 폐색장치는 이러한 기능적 회복에 큰 역할을 한다. 폐색장치가 구강 내에서 적절히 기능하기 위해서는 충분한 유지가 필요하며, 이러한 유지의 증가를 위해서는 폐색장치의 무게 감소가 필요하다. Hollow bulb 폐색장치에는 개방형, 폐쇄형 두 가지 형태가 존재한다. 폐쇄형 형태는 많은 장점을 가지나, 제작이 어렵고 누수가 발생할 경우 처치의 어려움 등의 단점이 존재하여 많은 술자들은 개방형 형태로 제작한다. 본 증례에서 두 열가소성 레진 시트로 만든 hollow body를 이용하여 one-step 중합 기술로 폐쇄형 hollow bulb 폐색장치를 제작하였고, 이는 기존의 폐쇄형 hollow 폐색장치 제작법의 단점들을 보완할 것이다.

• 교육시설
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• 제13권3호
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• pp.37-47
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• 2006

The conservation or practical use of a lot of closed schools which occurred from 1982 all over the country by governmental policy has been becoming important concerns to local resident and community with economical and administrative interest. A lot of examples, sold or rented to public institutions or a person, which have been using by welfare facilities for inhabitants, facilities for education, youth, company, culture and art, and other use, could be found. It could be said that the process of user's participation of these examples is very high, that is, a lot of examples of our surrounding is applied with ecological concept have participated by most users and local residents directly to architectural repair and renewal process, and practical use. In this background, I choose total five examples more than one by Chungbuk, Chungnam, Jeonbuk, Jeonnam district to investigate examples of closed schools applied ecological architectural concept and I researched reconfiguration of site, change of exterior or interior material, application of ecological system, and role as local community.

• 대한수학회보
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• 제54권6호
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• pp.2001-2011
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• 2017

In 1997, H. Li [12] proposed a conjecture: if $M^n(n{\geqslant}3)$ is a complete spacelike hypersurface in de Sitter space $S^{n+1}_1(1)$ with constant normalized scalar curvature R satisfying $\frac{n-2}{n}{\leqslant}R{\leqslant}1$, then is $M^n$ totally umbilical? Recently, F. E. C. Camargo et al. ([5]) partially proved the conjecture. In this paper, from a different viewpoint, we study closed convex spacelike hypersurface $M^n$ in locally symmetric Lorentz space $L^{n+1}_1$ and also prove that $M^n$ is totally umbilical if the square of length of second fundamental form of the closed convex spacelike hypersurface $M^n$ is constant, i.e., Theorem 1. On the other hand, we obtain that if the sectional curvature of the closed convex spacelike hypersurface $M^n$ in locally symmetric Lorentz space $L^{n+1}_1$ satisfies $K(M^n)$ > 0, then $M^n$ is totally umbilical, i.e., Theorem 2.

• 한국공간구조학회논문집
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• 제20권1호
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• pp.69-77
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• 2020

In this paper, the mean and fluctuating pressure coefficients derived from the results of wind tunnel tests on closed and open dome roofs were analyzed. The distribution characteristics of the fluctuating pressure according to the opening ratio and the height change were discussed. The analysis results showed that when the roof is open, the overall wind pressure decreases due to the open space, but more fluctuation occurred than the closed dome roof.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.423-433
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• 2002

A very fast method of moments(MoM) for the analysis of microstrip structure is considered based upon the use of rooftop basis and razor test functions in conjunction with a new closed-form Green's functions. The present method presents a robust approach to obtain the Green's functions which can be derived by use of only one set of approximation parameters independently of operating frequency range. Moreover, using the present MoM scheme, the MoM matrix elements can be analytically evaluated with few number of terms in comparison with the previous method. So, the computational efficiency can be improved significantly without loss of the precision. In order to check the validity of the present method, performance is demonstrated for the example of a coaxially-fed microstrip transmission line and the present results are compared with the previous results.

• 지식경영연구
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• 제11권4호
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• pp.1-19
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• 2010

With the increasing importance of ecosystem in a business environment, the value of open innovation is receiving great attention. Under open innovation, companies open their knowledge, capital, and other resources to cooperating companies; on the other hand, under closed innovation companies depend solely on their own resources. In this paper, we compare closed and open innovation using the simulation method, and confirm that in terms of total capital and production of the industry, open innovation provides greater opportunities to the entire ecosystem. Moreover, Schumpeterian competition, which is a dynamic of closed innovation, functions even under open innovation. Our findings highlight that not only small but also large companies can receive the benefit of an enlarged industry under open innovation.

• International Journal of Precision Engineering and Manufacturing
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• 제2권1호
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• pp.5-10
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• 2001

A method is proposed to obtain the Jacobian matrix of the 5 -bar parallel manipulator by employing the orthogonality between position and velocity vectors of rotating rigid-body around a fixed point. The dynamics of the 5-bar parallel manipulator is analyzed and utilized to design the computed-torque controller by developing a transformation matrix of the passive joints with respect to the active ones. In experimental demonstration, it shows that high-speed and accuracy tasks are performed by the proposed computed-torque control.