• 소음진동
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• 제11권1호
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• pp.111-117
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• 2001

Present work deals with a study on the deployment or retraction of cantilever beam that includes the rigid-body motion of large displacement of beam through the translational and rotational motions in 2-dimensional plane. The equations of motion are derived with respect to non-Cartesian coordinate system. In the formulation of equations of motion, shear deformations and geometrically non-linear effect are included. An assumed mode method is applied and numerical convergence characteristics are studied also. Types of motion of the moving beam are assumed to be classified as‘slow’or‘fast’motion, and the dynamic characteristics are investigated.

• 전자공학회논문지S
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• 제34S권1호
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• pp.54-64
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• 1997

In this paper, a method of dynamic modeling and a dynamic control of a mobile robot are presented to show the superiority of the dynamic control comparing to the PD control. This dynamic model is derived from the cartesian coordinates using lagrange equations. Based upon the derived dynamic model, we implemented the dynamic control of the mobile robot using the computed torque method. Time varying non-linear friction terms are not incroporated in this dynamic model. Instead, those are considered as disturbances. This uncertainty in dynamic model of mobile robot is compensated by the outer loop controller using PD algorithm. The validity of this model and the control algorithm are confirmed through the experiments, where the dynamic control algorithm demonstrated robust velocity tracking performance against the unmodeled non-linear frictions. The superiority of this algorithm is demonstrated by comparing to classical PD control algorithm.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 추계 학술대회논문집
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• pp.200-208
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• 2007

A methodology for the simulation of compressible high Reynolds number flow over rigid and moving bodies on a structured Cartesian grid is described in this paper. The approach is based on a modified version of the Brinkman Penalization method. To avoid oscillations in the vicinity of the body and to simulate shcok-containing flows, a Weighted Essentially Non-Oscillatory scheme is used to discretize the spatial flux derivatives. For high Reynolds number viscous flow, two turbulence models of the two-equation Menter's SST URANS model and a two-equation Detached Eddy Simulation are implemented. Some simple flow examples are given to assess the accuracy of the technique. Finally, a moving grid capability is demonstrated.

• 대한기계학회논문집A
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• 제27권6호
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• pp.1014-1019
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• 2003

A dynamic modeling method for beams undergoing overall rigid body motion is presented in this paper. Two special deformation variables are introduced to represent the stretching and the curvature and are approximated by the assumed mode method. Geometric constraint equations that relate the two special deformation variables and the cartesian deformation variables are incorporated into the modeling method. By using the special deformation variables, all natural as well as geometric boundary conditions can be satisfied. It is shown that the geometric nonlinear effects of stretching and curvature play important roles to accurately predict the dynamic response when overall rigid body motion is involved.

• 제어로봇시스템학회논문지
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• 제12권7호
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• pp.671-678
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• 2006

This article proposes a smooth path generation and time scheduling method for general tasks defined by non-smooth path segments in industrial robotic applications. This method utilizes a simple 3rd order polynomial function for smooth interpolation between non-smooth path segments, so that entire task can effectively maintain constant line speed of operation. A predictor-corrector type numerical mapping technique, which correlates time based speed profile to the smoothed path in Cartesian space, is also provided. Finally simulation results show the feasibility of the proposed algorithm.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(4)
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• pp.259-266
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• 1996

This paper presents a geometrically non-linear formulation for the general curved beam element based on assumed strain fields and Timoshenko's beam theory. This general curved beam element is formulated from constant strain fields. And this element, designed in a local curvilinear coordinate system, is transformed into a global cartesian system in order to analyze effectively the general curved beam structures located arbitrarly in space. Numerical examples are presented to show the accuracy and efficiency of the present formulation. The results obtained from the present formulation are compared with those available in the literature and analysis by ANSYS.

• 설비공학논문집
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• 제3권3호
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• pp.186-196
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• 1991

Numerical analysis has been performed to investigate the effects of the turbulence intensity and Prandtl number on the local heat transfer around a circular cylinder in crossflow. The governing equations were reformulated in a non-orthogonal coordinate system with Cartesian velocity components and discretised by the finite volume method with a non-staggered variable arrangement. For laminar flow, the calculations were performed for the Reynolds numbers 26 and 200. The results showed good agreement with the experimental results. For turbulent flow of the Reynolds number $1{\times}10^5$ and $2{\times}10^6$, the results showed that with an increase in the turbulent intensity in the main stream, the local Nusselt number increases in the front region of the circular cylinder. But the effect of turbulent intensity on the local Nusselt number diminishes in the wake region. The influence of Prandtl numbers show similar trend to that of turbulent intensity.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.220-225
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• 2007

Free vibration analysis using the method of NDIF (non-dimensional dynamic influence function), which was developed by the author, is extended to arbitrarily shaped polygonal plates with free edges. Local Cartesian coordinate systems are employed to apply the free boundary condition to nodes distributed along the edges of the plate of interest. Furthermore, a new way for applying the free boundary condition to nodes located at corners of the plate is for the first time introduced by considering the phenomenon of stress concentration at the corners. Two case studies show that the proposed method is valid and accurate when the eigenvalues by the proposed method are compared to those by FEM(ANSYS).

• 철학연구
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• 제147권
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• pp.239-260
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• 2018

기술의 시대에 새롭게 등장한 비인간존재인 인공지능로봇(A.I)은 인간에게 위협적인 존재인가 아니면 인간과의 상호협력 또는 앙상블을 이루는 존재인가? 인간이 과학기술의 힘을 빌어 자연을 지배하고자 하는 욕망은 인간이 자신을 소멸시킬 수 있다는 두려움으로 나타나고 있다. 본 연구는 이러한 물음과 두려움의 근저에 있는 데카르트적 인식론의 문제를 확인하고 시몽동과 라투르의 존재론 및 기술철학을 활용하여 메를로-퐁티의 몸살존재론을 토대로 이 물음들에 답하려는 시도이다. 데카르트 철학이 도출한 코기토는 인간-이성을 주체로 하여 '주관과 객관이라는 이분법적 인식론의 구조'의 토대가 되었다. 인간이 중심인 세계에서 인간 아닌 모든 존재들은 인간을 위한 도구이거나 통제의 대상이었다. 근대인의 문제는 인간을 비롯한 자연을 통제하는 방식에 자연과학적 방법에서 도움을 얻을 뿐 아니라, 과학적 방법만이 세계를 이해하는 유일한 방법이라고 생각한다는데 있다. 이를 비판하면서 메를로-퐁티는 몸이 인간과 비인간존재들을 매개한다는 것을 보여주며, 살존재론으로 그것이 가능한 존재론적 토대를 마련한다. 메를로-퐁티의 현상학적 방법론과 존재론은 기술철학자이자 현상학의 영향 아래에 있는 시몽동에 의해 새롭게 전개된다. 시몽동에 의해 인간과 비인간존재의 관계는 인간과 기술적 대상의 앙상블 또는 인간과 기술적 대상과의 상호협력적 공진화로 나타난다. 특히 라투르는 시몽동에서 한발 더 나아가 근대의 핵심 개념인 주체를 부정하고 세계에 거주하는 모든 몸들을 행위자네크워크이론으로 규정한다. 메를로-퐁티의 현상학적 관점은 기술시대의 철학적 논의에 새로운 가능적 근거가 될 수 있다. 우리는 근대적 두려움이 현상학적 태도로 전환함으로써 그 문제 자체가 해소될 수 있음을 확인할 것이다.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2681-2692
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• 1996

The finite-volume method for radiation in a three-dimensional non-orthogonal gas turbine combustion chamber with absorbing, emitting and anisotropically scattering medium is presented. The governing radiative transfer equation and its discretization equation using the step scheme are examined, while geometric relations which transform the Cartesian coordinate to a general body-fitted coordinate are provided to close the finite-volume formulation. The scattering phase function is modeled by a Legendre polynomial series. After a benchmark solution for three-dimensional rectangular combustor is obtained to validate the present formulation, a problem in three-dimensional non-orthogonal gas turbine combustor is investigated by changing such parameters as scattering albedo, scattering phase function and optical thickness. Heat flux in case of isotropic scattering is the same as that of non-scattering with specified heat generation in the medium. Forward scattering is found to produce higher radiative heat flux at hot and cold wall than backward scattering and optical thickness is also shown to play an important role in the problem. Results show that finite-volume method for radiation works well in orthogonal and non-orthogonal systems.