• Structural Engineering and Mechanics
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• 제70권6호
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• pp.711-722
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• 2019

Considering stress singularities at point support locations, buckling solutions for plates with arbitrary number of point supports are hard to obtain. Thus, new Hp-Cloud shape functions with Kronecker delta property (HPCK) were developed in the present paper to examine elastic buckling of point-supported thin plates in various shapes. Having the Kronecker delta property, this specific Hp-Cloud shape functions were constructed through selecting particular quantities for influence radii of nodal points as well as proposing appropriate enrichment functions. Since the given quantities for influence radii of nodal points could bring about poor quality of interpolation for plates with sharp corners, the radii were increased and the method of Lagrange multiplier was used for the purpose of applying boundary conditions. To demonstrate the capability of the new Hp-Cloud shape functions in the domain of analyzing plates in different geometry shapes, various test cases were correspondingly investigated and the obtained findings were compared with those available in the related literature. Such results concerning these new Hp-Cloud shape functions revealed a significant consistency with those reported by other researchers.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.272-276
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• 2000

Reverse engineering refers to the process that creates a physical part from acquiring the surface data of an existing part using a scanning device. In recent years, as the non-contact type scanning devices become more popular, the huge amount of point data can be obtained with high speed. The point data handling process, therefore, becomes more important since the scan data need to be refined for the efficiency of subsequent tasks such as mesh generation and surface fitting. As one of point handling functions, the cross-sectioning function is still frequently used for extracting the necessary data from the point cloud. The commercial reverse engineering software supports cross-sectioning functions, however, these are only for cross-sectioning the point cloud with the constant spacing and direction. In this paper, adaptive cross-sectioning point cloud which allow the changes of the spacing and directions of cross-sections according to the constant spacing and direction. In this paper, adaptive cross-sectioning algorithms which allow the changes of the spacing and directions of cross-sections according to the curvature difference of the point cloud data are proposed.

• 한국정보통신학회논문지
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• 제5권3호
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• pp.517-524
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• 2001

IEEE-754 부동소수점 표준을 지원하는 radix-2 SRT 제산기 유닛을 redundant binary (RB) 수치계를 이용하여 설계하였다. RB 수치계를 이용함으로써 기존의 2의 보수 수치계를 이용하는 경우에 비해 부분 몫 결정 회로의 동작속도를 약 20-% 향상시킴과 아울러 회로 단순화를 이루었다. 또한, 새로운 RB 가산기 회로를 제안함으로써 가수 제산기를 효율적으로 구현하여 기존의 방식에 비해 면적을 약 20-%의 감소시켰다. 설계된 부동소수점 제산기는 배정도 형식과 5가지의 예외처리 및 4가지의 반올림 모드를 지원하며, Verilog HDL로 설계되어 Verilog-XL로 검증하였다.

• Steel and Composite Structures
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• 제25권3호
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• pp.327-335
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• 2017

To gain more knowledge of aluminum foam sandwich structure and promote the engineering application, aluminum foam sandwich consisting of 7050 matrix aluminum foam core and 304 stainless steel face-sheets was studied under three-point bending by WDW-T100 electronic universal tensile testing machine in this work. Results showed that when aluminum foam core was reinforced by 304 steel face-sheets, its load carrying capacity improved dramatically. The maximum load of AFS in three-point bending increased with the foam core density or face-sheet thickness monotonically. And also when foam core was reinforced by 304 steel panels, the energy absorption ability of foam came into play effectively. There was a clear plastic platform in the load-displacement curve of AFS in three-point bending. No crack of 304 steel happened in the present tests. Two collapse modes appeared, mode A comprised plastic hinge formation at the mid-span of the sandwich beam, with shear yielding of the core. Mode B consisted of plastic hinge formation both at mid-span and at the outer supports.

• 대한전자공학회논문지SD
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• 제48권10호
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• pp.72-81
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• 2011

본 논문에서는 IEEE754 표준의 단정도 및 배정도를 지원하는 새로운 부동소수점 변환기를 제안하고 설계하였다. 제안된 변환기는 부호 있는 정수(32비트/64비트)와 부동소수점(단정도/배정도) 간 변환, 부호 없는 정수(32비트/64비트)를 부동소수점(단정도/배정도)으로의 변환, 부동소수점 단정도와 배정도 간 변환뿐만 아니라 부호 있는 고정소수점(32비트 64비트)과 부동소수점(단정도 배정도) 간 변환을 지원한다. 모든 입력 형태를 하나의 형태로 만드는 새로운 내부 형태를 정의함으로써 출력 형태의 표현 범위에 따른 오버플로우 검사를 쉽게 하도록 하였다. 내부 형태는 IEEE754 2008 표준에서 정의된 부동소수점 배정도의 확장된 형태(extended format)와 유사하다. 이 표준에서는 부동소수점 배정도의 확장된 형태(extended format)의 최소 지수부 비트폭은 15비트라고 명시하지만 제안된 컨버터를 구현하는데 11비트만으로도 충분하다. 또한 덧셈기가 대신 +1 증가기를 사용하면서 라운딩 연산과 음수의 정확한 표현이 가능하도록 변환기의 라운딩 스테이지를 최적화하였다. 단일 클럭 사이클 데이터패스와 5단 파이프라인 데이터패스를 설계하였다. 변환기의 두 데이터패스에 대한 HDL 모델을 기술한 후에 Synopsys design compiler를 사용하여 TSMC 180nm 공정 라이브러리로 합성하였다. 합성 결과의 셀 면적은 12,886 게이트(2입력 NAND 게이트 기준)이고 최대 동작 주파수는 411MHz이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.199-204
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• 2007

This research aimed at to develop a quantitative assesment technique which uses the measured displacements at the excavated plane during tunnel construction. Tunnel structure has a feature with long extents comparing to the excavated section so that the tunnel safety assesment is more effective by using the measured data of displacements. Tunnel structures show different structural behaviors due to the mechanical characteristics of ground and supports themselves, excavation methods and construction methods of supports, etc. From this point of view, it has very important meanings on the practical aspects that the measured data from the construction cite represent the features of the interaction effects between ground and supports as they are. In this study, both the stress state and the properties of surrounding ground are analyzed by newly incorporated feedback analysis technique which can use the measured displacements directly. Then, the stress state and the properties of ground will be used to obtain the strain distribution of surrounding ground. Finally the tunnel safety can be assessed by comparing the estimated strain through the analysis to the allowable strain of ground quantitatively.

• 한국시뮬레이션학회논문지
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• 제7권2호
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• pp.115-123
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• 1998

A simulation is performed to investigate the effect of the pipe supports on the change of the natural frequencies of curved pipe systems containing fluid flow, for different elbow angles and geometry of the pipe systems. Based upon the Hamilton's principle, the equations of motions are derived, and the finite element equation is constructed to solve the corresponding eigenvalue problem. The angles of elbows do not affect the change of the fundamental natural frequency, but affect the change of the third or higher natural frequencies. Without any support, the change of the fundamental natural frequency due to the geometric change is smaller than the change of the second or higher natural frequencies. The more curve parts exist in the pipe system, the less change of lower frequency range, compared with the change of higher frequency range, is observed. Spring supports can be used to reduce the fundamental natural frequency, without change of the second or higher natural frequencies. To avoid resonance, which is critically dangerous from the view point of structural dynamics, the mechanical properties such as stiffness or the location of pipe supports are need to be changed to isolate the natural frequencies from the frequency range of dominant vibration modes.

• 한국컴퓨터정보학회논문지
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• 제14권12호
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• pp.225-232
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• 2009

소프트웨어 규모 측정에 국제표준(IFPUG, FPA)에 기반한 기능점수 방식은 개발자 관점이 아닌 사용자 관점의 접근이라는 장점으로 널리 활용되고 있다. 그러나 현재의 기능점수 측정 방식은 복잡도 적용에서의 상한이 존재하는 등 문제점을 내포하고 있다. 본 논문에서는 이러한 복잡도 상한의 문제를 극복하고, 회귀식을 내장하고 있어 쉽게 소프트웨어 규모를 측정할 수 있으며, 특히 대형 애플리케이션에도 적용할 수 있는 개선된 기능점수 측정모델을 제시한다. 조직내에서 운영중인 10개 애플리케이션에 적용하여 적합성을 평가한 결과, 제시한 개선 모형이 기존의 FPA(Function Point Analysis) 방식보다 LOC(Line of Code) 규모를 비교하여 상관관계가 더 높은 장점을 확인할 수 있었다.

• 한국공간정보시스템학회 논문지
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• 제11권2호
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• pp.39-44
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• 2009

In order to make the effect of the navigation system more direct, the paper proposes a thought of vehicle navigation system based on Video-GIS. A semantic framework has been defined whose core is focused on the integration and interaction of video and spatial information, which supports full content retrieval based on multimodal metadata extraction and fusion, and supports kinds of wireless access mode. Furthermore, requirements of prototype system are discussed. Then the design and implementation of framework are discussed. Next, describe the key ideas and technologies involved. Finally, we point out its future research trend.

• 한국항공운항학회지
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• 제20권4호
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• pp.115-125
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• 2012

The purpose of this study is to investigate the relationship between organizational culture(constructive and defensive culture) and emotional labor along with the social supports (supervisor support, colleague support). Using data obtained from a survey of 419 flight attendants of a major airline company in south Korea. The results are as follows: Organizational culture had a significant effect on emotional labor. At this point, colleague support mediated the relationship between constructive culture and emotional labor. In addition, supervisor support and colleague support had a mediating role between defensive culture and emotional labor. This result concludes that flight attendants positively accept the essential manuals and safety regulations in the special working condition with a unified team service. Furthermore, the results show that social supports are an important job resource for flight attendants helping them reach their work-related goals.