• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.467-474
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• 2013

Construction contactors must continuously seek to improve their cash flows, which reside at the heart of their financial success. They require careful planning, analysis, and optimization to avoid the risk of bankruptcy, remain profitable, and secure long-term growth. Sources of cash include bank loans and retained earnings, which are conceptually similar in that they both incur a cost of capital. Financial management therefore requires accurate yet customizable modeling capabilities that can quantify all expenses, including said cost of capital. However, currently existing cash flow models in construction engineering and management have strongly simplified the manner in which interest is assessed, which may even lead to overstating it at a disadvantage to contractors. The variable nature of cash balances, especially in the early phases of construction projects, contribute to this challenging issue. This research therefore extends a new cash flow model with an accurate interest calculation. It utilizes singularity functions, so called because of their ability to flexibly model changes across any number of different ranges. The interest function is continuous for activity costs of any duration and allows the realistic case that activities may begin between integer time periods, which are often calendar months. Such fractional interest calculation has hitherto been lacking from the literature. It also provides insights into the self-referential behavior of compound interest for variable cash balances. The contribution of this study is twofold; augmenting the corpus of financial analysis theory with a new interest formula, whose strengths include its generic nature and that it can be evaluated at any fractional value of time, and providing construction managers with a tool to help improve and fine-tune the financial performance of their projects.

• Structural Engineering and Mechanics
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• 제70권3호
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• pp.279-287
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• 2019

This paper intends to introduce a near-tip grid refinement and to explore its usefulness in the crack analysis by the natural element method (NEM). As a sort of local h-refinement in FEM, a NEM grid is locally refined around the crack tip showing the high stress singularity. This local grid refinement is completed in two steps in which grid points are added and Delaunay triangles sharing the crack tip node are divided. A plane-state plate with symmetric edge cracks is simulated to validate the proposed local grid refinement and to examine its usefulness in the crack analysis. The crack analysis is also simulated using a uniform NEM grid for the sake of comparison. The near-tip stress distributions and SIFs that are obtained using a near-tip refined NEM grid are compared with the exact values and those obtained using uniform NEM grid. The convergence rates of global relative error to the total number of grid points between the refined and non-refined NEM grids are also compared.

• 한국공간구조학회논문집
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• 제4권1호
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• pp.39-48
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• 2004

Generally, a structural system with large inextensional deformations, or in other words, non-strained deformation is called as 'Unstable Structure', Truss-linked structures, cable structures, membrane structures and movable structures as foldable space structures etc, are included in this category. In this paper, a dynamic analysis method for unstable structural systems is presented. Governing equations for dynamic analysis of unstable truss structures with inextensional displacements are derived. Because of singularity of inverse matrixin in practical analysis of unstable structure, the generalized inverse matrix is Introduced to resolve the singular problem. Also, the RREF technique is used to get the inextensional displacement mode. Two unstable truss structures are analyzed by using presented method. Damping is not considered. From the given results, it is known that proposed method is useful to figure out the dynamic behavior of unstable truss structures.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 봄 학술발표회 논문집
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• pp.71-78
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• 1997

The high precision analysis by the p-version of the finite element method are fairly well established as highly efficient method for linear elastic problems, especially in the presence of stress singularity. It has been noted that the merits of p-version are accuracy, modeling simplicity, robustness, and savings in user's and CPU time. However, little has been done to exploit their benefits in elasto-plastic analysis. In this paper, the p-version finite element model is proposed for the materially nonlinear analysis that is based on the incremental theory of plasticity, the associated flow rule, and von-Mises yield criteria. To obtain the solution of nonlinear equation, the Newton-Raphson method and initial stiffness method, etc are used. Several numerical examples are tested with the help of the square plates with cutout, the thick-walled cylinder under internal pressure, and the center cracked plate under tensile loading. Those results are compared with the there cal solutions and the numerical solutions of ADINA software.

• Wind and Structures
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• 제14권4호
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• pp.359-381
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• 2011

This paper deals with the flutter instability problem of flexible bridge decks in the framework of bimodal-coupled aeroelastic bridge system analysis. Based on the analysis of coefficients of the polynomials deduced from the singularity conditions of an integral wind-structure impedance matrix, a set of simplified formulations for calculating the critical wind velocity and coupled frequency are presented. Several case studies are discussed and comparisons with available approximated approaches are made and presented, along with a conventional complex eigenvalue analysis and numerical results. From the results, it is found that the formulas that are presented in this study are applicable to a variety of bridge cross sections that are not only prone to coupled-mode but also to single-mode-dominated flutter.

• 대한기계학회논문집A
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• 제25권8호
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• pp.1253-1260
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• 2001

Transient thermal analysis of a three-dimensional axisymmetric automotive disk brake is presented in this paper. Temperature fields are obtained using a hybrid FFT-FEM scheme that combines Fourier transform techniques and finite element method. The use of a fast Fourier transform algorithm can avoid singularity problems and lead to inexpensive computing time. The transformed problem is solved with finite element scheme for each frequency domain. Inverse transforms are then performed for time domain solution. Numerical examples are presented for validation tests. Comparisons with analytical results show very good agreement. Also, a 3-D simulation, based upon an automotive brake disk model is performed.

• 한국자동차공학회논문집
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• 제2권4호
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• pp.80-90
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• 1994

Basic constraint equations derived from orthogonality conditions between a pair of body-fixed vectors and a body-fixed vector or a vector between two bodies are reformulated by using relative coordinate kinematics between two adjacent reference frames. Arithmetic numbers of operations required to compute derivatives of the constraint equations are drastically reduced. A mixed formulation of relative and cartesian coordinates is developed to further simplify derivatives of the constraints. Advantages and disadvantages of the new formulation are discussed. Possible singularity problem of para llelism constraints is resolved by introducing an extra generalized coordinate. Kinematic analysis of a McPherson strut suspension system are carried out to illustrate use and efficiency of the new formulation.

• 한국통신학회논문지
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• 제38C권2호
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• pp.208-212
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• 2013

부류안 분산 행렬의 특이성 때문에 선형 판별 분석은 작은 표본 크기 문제에 쓰기에 알맞지 않다. 이에 선형 판별 분석을 확장하여 작은 표본 크기 문제에서 좋은 성능을 갖는 영 공간 기반 선형 판별 분석이 제안되었다. 이 논문에서는 라그랑지 기법을 바탕으로 하여, 영 공간 기반 선형 판별 분석을 써서 특징을 추출하는 문제를 선형 방정식 문제로 바꾸는 과정을 제안하였다.

• 한국융합학회논문지
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• 제13권4호
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• pp.7-15
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• 2022

정보와 기술의 탈중앙화/분권, 공유/개방, 연결을 통한 개별 맞춤 시대의 지능화 세계 지향으로 그 어느 때 보다도 인공지능에 대한 관심과 기술적 담론 속에 기대와 우려가 교차하는 경향을 자주 보게 된다. 최근에는 2045년 전, 후로 AI의 특이성(Singularity)이 나타날 것이라는 미래학자들의 주장도 쉽게 찾아볼 수 있다. 이제는 다가올 인공지능 시대에서 AI와 함께 상생하고 번영하는 공존 패러다임을 만들기 위한 준비의 일환으로 보다 올바른 AI 윤리와 규제 설정을 위한 표준 프레임워크가 요구되고 있다. 주요지침 설정 누락의 위험성 배제와 타당하고 보다 합리적인 지침 항목과 평가 기준을 가늠 할 수 있는 방안이 점차 큰 연구문제로 나타나고 있기 때문이다. 이런 연구문제 해결과 동시에 AI 윤리와 규제 설정에 대한 지속적인 경험과 학습효과가 연결 발전될 수 있도록 국제기구/국가/기업의 AI 윤리와 규제에 대한 가이드 라인 자료 등을 수집하여 설정 연구모형과 텍스트 마이닝 탐색 분석을 통해 표준 프레임워크(SF: Standard Framework) 설정 방안을 연구 제시한다. 본 연구결과는 향후 보다 발전적인 AI 윤리와 규제지침 항목 설정과 평가 방안연구에 기초 선행연구 자료로 기여될 수 있을 것이다.

• 한국언론정보학보
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• 제81권
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• pp.40-74
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• 2017

서울시 마을미디어에 관한 분석작업을 통해 이 연구는 첫째, 공동체의 생성 원리는 본질적으로 정해져 있지 않으며 하나이지도 않으며 각기 고유성과 서로 간의 상이성을 띤다는 점, 둘째, 공동체 생성에 있어 역사적 맥락성, 사회적 조건성, 문화적 정향성, 주체의 의지와 열망의 접합이 주요한 요인으로 작동한다는 점, 셋째, 공동체의 형성에는 상이한 권력과 욕망이 전략적으로 연동한다는 점, 넷째, 공동체의 생성은 공동체의 활동, 특히 소통적인 활동과 동시적으로 이루어지며 공동체는 곧 소통과 동의어라는 점, 다섯째, 공동체는 사회의 순조건 안에서 배양되는 것이라기보다는 위태성, 부정성, 한계성을 껴안으며 되어가는 것이라는 점, 마지막으로 공동체는 고유한 감수성과 표현성을 생성하면서 특이한 문화적 언어를 표현한다는 점을 제안한다. 이를 통해 동질적이고 동질적 총체로 단순화하는 대신, 이질적인 타자들 사이의 접속과 해리, 수렴과 발산, 동일성과 차이의 계속되는 역동으로서 공동체를 개념화할 수 있다.