• Korean Journal of Mathematics
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• 제22권2호
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• pp.349-354
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• 2014

In this paper, we establish convergence of contraction $C_0$ semigroups in the weak topology on a general Banach space. We remove the restriction on a Banach space X and weaken the condition on resolvents of generators in the previous results [4, 5].

• 한국정보과학회논문지:시스템및이론
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• 제31권10호
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• pp.593-602
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• 2004

정렬되지 않은 3차원 측정점들로부터 이들을 근사하는 표면을 재구성하는 방법을 제안하였다. 제안된 방법은 경계면 축소포장 방식에 의한 표면 재구성 방법(shrink-wrapped boundary face： SWBF) 으로, 측정점으로부터 경계셀과 경계면을 구해 초기 메쉬를 생성하고 이를 연속적으로 축소하는 방식에 의해 표면을 재구성한다. 제안된 방법은 기존의 표면 축소포장 방식의 메쉬 생성 방법의 문제점인 물체의 토폴로지에 대한 제약이 없이 어떠한 형태의 표면 재구성에도 적용이 가능하며, 기존 방법이 축소 단계에서 각 메쉬 정점에 대한 최단거리 측정점을 찾는 전역 탐색을 해야 하는데 비해 지역 탐색만으로 최적의 측정점을 찾을 수 있으므로 처리 시간 측면에서도 우월하다. 실험을 통해 제안된 표면 재구성 알고리즘이 측정점들간의 관계를 알 수 없는 정렬되지 않은 3차원 점들에 대한 표면 재구성에 매우 안정적이고 효과적임을 확인할 수 있었다.

• 대한수학회지
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• 제42권1호
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• pp.129-134
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• 2005

Lpt X be a reduced Stein space and L a holomorphic line bundle on X. L is spanned by its global sections and the associated holomorphic map $h_L\;:\;X{\to}P(H^0(X, L)^{\ast})$ is an embedding. Choose any locally convex vector topology ${\tau}\;on\;H^0(X, L)^{\ast}$ stronger than the weak-topology. Here we prove that $h_L(X)$ is sequentially closed in $P(H^0(X, L)^{\ast})$ and arithmetically Cohen -Macaulay. i.e. for all integers $k{\ge}1$ the restriction map ${\rho}_k\;:\;H^0(P(H^0(X, L)^{\ast}),\;O_{P(H^0(X, L)^{\ast})}(k)){\to}H^0(h_L(X),O_{hL_(X)}(k)){\cong}H^0(X, L^{\otimes{k}})$ is surjective.

• ETRI Journal
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• 제27권2호
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• pp.235-238
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• 2005

A new mesh reconstruction scheme for approximating a surface from a set of unorganized 3D points is proposed. The proposed method, called a shrink-wrapped boundary face (SWBF) algorithm, produces the final surface by iteratively shrinking the initial mesh generated from the definition of the boundary faces. SWBF surmounts the genus-0 spherical topology restriction of previous shrink-wrapping-based mesh generation techniques and can be applied to any type of surface topology. Furthermore, SWBF is significantly faster than a related algorithm of Jeong and others, as SWBF requires only a local nearest-point-search in the shrinking process. Our experiments show that SWBF is very robust and efficient for surface reconstruction from an unorganized point cloud.

• 대한기계학회논문집A
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• 제29권3호
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• pp.503-510
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• 2005

In this paper, the topology optimization of inner-wall stiffener of cylindrical containers for the use as a rocket fuel tank is presented. Such structures for space mission should have high stiffness against the buck]ins while their weight should be maintained low from the viewpoint of cost and performance. Therefore, in the present work the reciprocal of critical buckling load is adopted as an objective function and the total mass of stiffener is constrained to a prescribed value. Due to the restriction of computational resources a section of cylindrical container is topologically optimized and this result is repeated to obtain the full design. Also, for manufacturability the concept of periodic topology pattern in design domain is newly introduced. In the numerical examples, the results by the proposed approach are investigated and compared with those of isogrid design.

• 한국통신학회논문지
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• 제34권1B호
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• pp.10-15
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• 2009

최근 센서 네트워크에 대한 중요성이 강조 되면서 응용분야도 점차 증가하고 있는 추세이다. 센서 네트워크를 위한 다수의 프로토콜들이 개발되었고 계층구조망을 위한 연구들이 에너지 효율적인 면에서 좋은 평가를 받고 있다. 계층구조망을 위한 라우팅 프로토콜 중 가장 대표적인 프로토콜이 LEACH이다. 하지만 LEACH관련 프로토콜은 메시지 전송 시 네트워크 전체 단위로 통신을 함으로서 발생하는 다양한 문제점을 가지고 있다. 본 논문에서는 LEACH관련 기법들의 문제점을 해결할 수 있는 새로운 클러스터링 기법을 제안한다. 제안하는 기법은 센서노드의 메모리 제약성을 역으로 이용하여 클러스터링을 구성한다. 성능평가 결과 본 논문에서 제안한 클러스터링 기법은 LEACH에 비해 네트워크의 균형 있는 클러스터 분산을 제시할 수 있었고, LEACH보다 약 1.8배 오랜 네트워크 생존기간을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.473-476
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• 2000

WDM is a very promisinig technique for the realization of future All-Optical networks. WDM gives an advantage of high rate transmission without delay for Electronic/optical conversion. But the available number of wavelengths is limited by technical restriction. so the efficient optical path routing and wavelength assignment is needed. this paper is concerned with the efficient design of WDM optical transport networks. RWA assumes that the connection demands between node pairs are given. the objective of RWA is to minimize the number of wavelengths. these design consider the static routing and wavelength assignment in the network of arbitrary topology. To solve these problems, this paper proposes some heuristic algorithms.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1374-1378
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• 2004

Railway conflict detection and resolution problem (RCDRP) involves complicated field constraints that should be considered for practical service. In this paper, we address those constraints in brief. Particularly, following situations are addressed; (1) temporal change of network topology, (2) consideration of diverse conditions of track and train, for example, single/double tracks and passenger/freight service, (3) siding capacity limitation, (4) bidirectional sides used by both inbound and outbound trains, (5) regulation for passenger transfer service, (6) consideration of siding length, (7) Restriction on stopping before the track segment with steep slope.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.393-405
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• 2009

The Purpose of this paper is to show the applicability of a methodology, developed by the authors, with which to perform the mechanical optimization of space truss structures strongly restricted. This methodology use a parameter call "Volumetric Displacement", as the Objective Function of the optimization process. This parameter considers altogether the structure weight and deformation whose effects are opposed. The Finite Element Method is employed to calculate the stress/strain state and the natural frequency of the structure through a structural linear static and natural frequency analysis. In order to show the potentially of this simple methodology, its application on a large diameter telescope structure (10 m) considering the strongly restriction that became of its use, is presented. This methodology, applied in previous works on continuous structures, such as shell roof and fluid storage vessels, is applied in this case to a space truss structure, with the purpose of generalize its applicability to different structural topology. This technique could be useful in the morphology design of deployable and retractable roof structures, whose use has extensively spread in the last years.

• 한국정밀공학회지
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• 제21권9호
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• pp.127-134
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• 2004

It is difficult to have the existing structural optimization using coupled field analysis from CFD to structure analysis when the structure is influenced of fluid. Therefore in an initial model of this study after doing parameter design from the background of shape using topology optimization. and it is making a approximation formula using by the CFD-structure coupled-field analysis and design of experiment. By using this result, we conducted multi-objective optimization. We could confirm efficiency of stochastic method applicable in the scene of structure reliability design to be needed multi-objective optimization. And we presented a way of design that could overcome the time and space restriction in structural design such as the butterfly valve with the less experiment.