• 대한수학회논문집
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• 제26권2호
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• pp.297-304
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• 2011

In this paper, we introduce closure operators [${\cdot}$]c and [${\cdot}$]a on a space and study some relations among [${\cdot}$]c, [${\cdot}$]a and countable tightness. We introduce the concepts of a strongly sequentially closed set and a strongly sequentially open set and show that a space X has countable tightness if and only if every strongly sequentially closed set is closed if and only if every strongly sequentially open set is open. Finally we find a generalization of the weak Fr$\'{e}$chet-Urysohn property which is equivalent to countable tightness.

• 대한치과교정학회지
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• 제52권3호
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• pp.236-245
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• 2022

New digital technologies, many involving three-dimensional printing, bring benefits for clinical applications. This article reports on the clinical procedure and fabrication of a skeletally anchored mesialization appliance (Mesialslider) using computer-aided design/computer-aided manufacturing (CAD/CAM) for space closure of a congenitally missing lateral incisor in a 12-year-old female patient. The insertion of the mini-implants and appliance was performed in a single appointment. Bodily movement of the molars was achieved using the Mesialslider. Anchorage loss, such as deviation of the anterior midline or palatal tilting of the anterior teeth, was completely avoided. CAD/CAM facilitates safe and precise insertion of mini-implants. Further, mini-implants can improve patient comfort by reducing the number of office visits and eliminating the need for orthodontic bands and physical impressions.

• 대한수학회보
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• 제22권1호
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• pp.17-22
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• 1985

B.M. Munshi and D.S. Bassan defined and developed the concept of super continuity in [5]. The concept has been investigated further by I. L. Reilly and M. K. Vamanamurthy in [6] where super continuity is characterized in terms of the semi-regularization topology. Super continuity is related to the concepts of .delta.-continuity and strong .theta.-continuity developed by T. Noiri in [7]. The purpose of this note is to derive relationships between super continuity and other strong continuity conditions and to develop additional properties of super continuous functions. Super continuity implies continuity, but the converse implication is false [5]. Super continuity is strictly between strong .theta.-continuity and .delta.-continuity and strictly between complete continuity and .delta.-continuity. The symbols X and Y will denote topological spaces with no separation axioms assumed unless explicity stated. The closure and interior of a subset U of a space X will be denoted by Cl(U) and Int(U) respectively and U is said to be regular open (resp. regular closed) if U=Int[Cl(U) (resp. U=Cl(Int(U)]. If necessary, a subscript will be added to denote the space in which the closure or interior is taken.

• 한국항공우주학회지
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• 제42권9호
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• pp.745-751
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• 2014

멀티 노즐로 구성된 추진기관의 경우, 각 노즐별 노즐마개 파열압력의 편차가 초기 분력을 유발하고 유도탄의 비행안정성에 영향을 미친다. 따라서 노즐마개 설계 시 먼저 형태별로 파열거동을 분석하여 원하는 파열압력에서 균일하게 파열되는지를 확인해야 한다. 본 연구에서는 평판형, "+" 노치형 노즐마개에 대한 파열거동을 실험적, 해석적인 방법으로 분석하였다. 실험 시 저장온도, 노치의 유무, 노치방향에 따른 노즐마개 파열압력 및 편차를 분석하였다. 그리고 유한요소해석을 통해 노즐마개의 파열거동을 순차적으로 분석하고, 그 결과를 실험값과 비교하여 정확성을 검증하고자 하였다. 해석 시 상용프로그램인 Abaqus/Explicit를 사용하였고, 파손모델은 Johnson-cook 전단파손모델을 적용하였다.

• 터널과지하공간
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• 제3권2호
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• pp.142-151
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• 1993

In this study, the deformation characteristics of atrtificially fractured joints of granite under normal and shear loading were investigated. To obtain the characteristics of joint deformation, compression and shear tests were performed in the laboratory on three different sizes of rock specimens. The rock used in the experimens was Iksan granite. Joints were produced artificially by fracturing using the apparatus for generating extension-joint. Joint normal deformability was studied by conducting cyclic loading tests on the joints. Joint closure varied non-linearly with normal stress through cyclic loadings. As normal stress increased, the joints gradually reached a state of maximum joint closure. The relation between normal stress and joint closure for mated and unmated joints was well described by the hyperbolic and exponential function, respectively. Joint shear deformability was studied by performing direct shear tests under normal stresses on the joints. it was shown that the behaviour in the prepeak range was non-linear and joint shear stiffness depended on the size of specimen and the normal stress.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권3호
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• pp.231-239
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• 2014

It presents the concepts of ordinary smooth interior and ordinary smooth closure of an ordinary subset and their structural properties. It also introduces the notion of ordinary smooth (open) preserving mapping and addresses some their properties. In addition, it develops the notions of ordinary smooth compactness, ordinary smooth almost compactness, and ordinary near compactness and discusses them in the general framework of ordinary smooth topological spaces.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.45-51
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• 2023

During the operation of a nuclear power plant (NPP), the waste reactor vessel closure head (RVCH) that is replaced owing to design or manufacturing defects is buried in a designated area or temporarily stored in a radiation shielding facility within the NPP. In such cases, storing it for extended periods proves a challenge owing to space constraints in the power plant and a safety risk associated with radiation exposure; therefore, dismantling it quickly and safely is crucial. However, not much research has been done on the dismantling of the RVCH in an operational power plant. This study proposes a dismantling process based on the radioactive contamination level measured for the Kori #1 RVCH, which is currently being discarded and stored, and examines the decontamination and cutting according to this process. In addition, the amount of secondary waste and dismantling cost are evaluated, and the dismantling effect of the reactor closure head is analyzed.

• 대한치과교정학회:학술대회논문집
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• 대한치과교정학회 1997년도 제30회 학술대회
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• pp.51.1-51.1
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• 1997

• 대한치과교정학회지
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• 제24권1호
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• pp.95-104
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• 1994

전치부 공극의 치료법으로는 교정적인 폐쇄, 수술에 의한 방법, 보철에 의한 치료등의 방법이 있으며 이중 교정적인 폐쇄에 의한 치료법은 가장 보존적인 방법으로 많이 사용되고 있으나 그 치료이후의 보정에 많은 문제가 있었다. 저자등은 전치부 공극을 가진 3증례의 치료후 재발과정과 보정과정을 관찰한 결과 다음과 같이 요약할 수 있었다. 양 중절치가 서로 직접 연결되지 않는 보정장치의 사용은 영구보철물에 의한 경우에도 재발을 가져왔다. $\cdot$ 교정적으로 공극을 폐쇄한후, 순소대절제술, circumferential supracrestal fibrotomy 그리고 양 중절치가 서로 연결된 설측 부착 보정장치의 시행으로 좋은 유지 효과를 얻었다. 이상의 결과로 미루어 볼때 전치부 공극은 교정적 치료후, 순소대절제술, fibrotomy등을 시행한 후 반드시 양 중절치를 연결하는 고정성 보정 장치가 필요하다고 생각된다.

• 대한치과교정학회지
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• 제35권6호
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• pp.451-458
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• 2005

측모두부방사선사진의 중첩만으로는 교합평면상의 치아이동을 알 수 없으며, occlusogram 역시 촬영 및 중첩의 오류를 피할 수 없다. 본 연구는 석고모형의 3차원 영상을 촬영한 후 3차원 영상 소프트웨어를 이용하여 중첩된 영상을 통해 상악 소구치 발치공간 폐쇄 후 상악 구치부의 회전양상을 알아보고자 하였다. 성인여성 19명을 연구대상으로 하여 치료 전 석고모형 및 치료 완료 후 석고모형의 3차원 영상을 촬영한 후, 상악 경구개면을 기준으로 두 영상을 중첩한 다음, 치료 전후의 상악 구치부의 회전양상을 비교 분석하였다. 연구결과 구치부의 회전 양상은 매우 다양하였다. 그 주요 원인은 치료 전 상악 구치의 다양한 회전 상태와 치열궁 및 치아의 형태학적인 특성 때문인 것으로 추측되었다. 따라서 발치공간 폐쇄 시 일어나는 구치의 회전 양상을 3차원 영상을 이용하여 정확히 평가하기 위해서는 치료 전후에 일어나는 구치의 회전을 초기 배열 전후의 구치 회전, 발치공간 폐쇄 전후의 구치 회전, 그리고 마무리 단계 전후의 구치 회전으로 세분하여 평가해야 함을 알 수 있었다.