• 한국전산유체공학회지
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• 제5권1호
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• pp.14-21
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• 2000

A method of two and three dimensional orthogonal grid generation with control of spacing by using the covariant Laplace equation is presented. An important feature of the methodology is its ability to control effectively the grid spacing especially near the boundaries still maintaining good orthogonality in whole field. The method is based on the concept of decomposition of the global transformation into consecutive transformation of an approximate conformal mapping and an auxiliary orthogonal mapping to have linear and uncoupled equations. Control of cell spacing is based on the concept of reference arc length, and orthogonal correction is peformed in the auxiliary domain. It is concluded that the methodology can successfully generate well controlled orthogonal grids around bodies of 2 and 3 dimensional configurations.

• 전자공학회논문지B
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• 제31B권8호
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• pp.119-128
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• 1994

In this paper we propose a new method for the recognition of 2-D partially occluded objects. The border of the object is transformed to a curve in arc length-accumulated interior angle plane. The transformed curve of an image is partitioned so that each segment is bounded by the concave interior angles. In order to tolerate shape distortion due to the polygonal approximation of the boundary of the object a group of feature points of the input image are matched with those of model views. The estimation method for positions and orientations of the identified objects objects is presented.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.9-18
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• 1996

The primary objective of this paper is to grasp many characteristics of buckling behavior of latticed spherical domes under various conditions. The Arc-Length Method proposed by E.Riks is used for the computation and evaluation of geometrically nonlinear fundamental equilibrium paths and bifurcation points. And the direction of the path after the bifurcation point is decided by means of Hosono's concept. Three different nonlinear stiffness matrices of the Slope-Deflection Method are derived for the system with rigid nodes and results of the numerical analysis are examined in regard in geometrical parameters such as slenderness ratio, half-open angle, boundary conditions, and various loading types. But in case of analytical model 2 (rigid node), the post-buckling path could not be surveyed because of Newton-Raphson iteration process being diversed on the critical point since many eigenvalues become zero simultaneously.

• Steel and Composite Structures
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• 제28권2호
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• pp.149-165
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• 2018

Using the modified couple stress theory and Euler-Bernoulli beam theory, this paper studies nonlinear vibration analysis of microbeams resting on the nonlinear orthotropic visco-Pasternak foundation. Using the Hamilton's principle, the set of the governing equations are derived and solved numerically using differential quadrature method (DQM), Newark beta method and arc-length technique for all kind of the boundary conditions. First convergence and accuracy of the presented solution are demonstrated and then effects of radius of gyration, Poisson's ratio, small scale parameters, temperature changes and coefficients of the foundation on the linear and nonlinear natural frequencies and dynamic response of the microbeam are investigated.

• 한국기계가공학회지
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• 제20권1호
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• pp.7-15
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• 2021

Buckling of cylindrical structures has been extensively researched, because it is an important phenomenon to be considered in structural design. However, the evaluation of thermal effects on the buckling of cylindrical structures has been insufficient; therefore, this study evaluates this thermal effect using shell elements. In addition, the thermal effect on the buckling of temperature-dependent nonlinear materials was evaluated. Nonlinear and linear buckling analyses were performed using the arc-length method to investigate the behavioral characteristics of a cylindrical structure. The basic theory of the linear buckling analysis of a cylindrical structure subjected to thermal stress was derived and presented by applying the thermal stress basic theory.

• 플랜트 저널
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• 제4권3호
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• pp.60-65
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• 2008

Power plant industry has been developed at high-capacity, high-technology, and innovation. Steam turbine became the most useful equipment that dominate more than 50% of all the world electricity production. And developed new materials of the turbine blade and extended length of the turbine last blade brought reform in steam turbine performance upgrade. In this paper, when do partial load driving in high-capacity steam turbine, optimum driving method found whether there is something. In operating steam turbine, there is a lot of loss from secondary wake and throttle of the 1st stage nozzle by the biggest leading factor that load fluctuation affects in high-pressure steam turbine performance. Effect of internal efficiency by 1 stage nozzle is the biggest here, but here fluid flow and flow analysis were not yet examined closely definitely. So, Analyzed design data and acceptance performance test result to applying subcritical pressure drum type 560 MW, supercritical-pressure once through type 500 MW, and 800 MW steam turbines actually. In conclusion, at partial load driving, partial arc admission(PAA) is more efficient than full arc admission(FAA) efficiency. This is judged by because increase being proportional with gross energy of stream that is pressure - available energy if pressure of stream that is flowed in to the turbine increases, available energy becomes maximum and turbine efficiency improves. Therefore, turbine performance is that preview that first stage performance fell if decline is serious in partial load because first stage performance changes according to load.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.83-88
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• 2004

최근 강구조물과 해양구조물에 있어서 박판 부재인 고장력강이 널리 사용되면서 좌굴이 발생할 가능성이 커지고 있다. 특히 선박구조는 상자형 박판 구조물로서 용접이나 절단등의 열 가공에 의하여 필연적으로 판부재에 초기처짐이 발생하게 된다. 이러한 초기처짐은 박판부재가 좌굴을 동반한 복잡한 비선형 거동을 나타낼 때 악영향을 미치는 요소이다. 결과적으로 선체구조물이나 해양구조물에 안정성과 정확성을 부여하기 위해서는 발생 가능한 초기처짐을 이상화 하여 2차좌굴을 고려한 초기구조설계에 반영하여야 한다. 본 연구에서는 종방향 압축하중이 작용하고 네변 단순지지조건인 판에 실제 계측된 여러 가지 초기처짐형상을 적용한 유한요소 시리즈 해석을 하였다. 해석방법으로서는 범용유한요소프로그램인 ANSYS의 탄소성대변형 유한요소법을 적용하였고 해석제어는 Newton-Raphson method와 An-length method를 병용하였다.

• 복식문화연구
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• 제14권5호
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• pp.840-849
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• 2006

Breast volume has been approximately estimated under the assumption that the shape of breast is a corn. However, women's breast is more like a bulged bag in reality. In this paper, three methods of breast volume estimation were compared to find out the more accurate method. The shape of the breast is assumed as a hemisphere in the first estimation method and a corn in the second one. In the third method, arc along the cross sectional shape of breast was utilized in the calculation. Comparisons among the methods were made using the actual 3D volume measurement of thirty seven women's breast. As results, the third method was the best one for the normal breast type, especially for the lower part of the breast ($R^2=0.74$) which is the crucial design parameter of the brassiere. Assumption of the shape of breast as a corn was reasonably acceptable when the breast is sagged. It was expected that when women wore brassiere, the accuracy of the third method would increase more, since the shape of breast becomes more symmetrical.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.651-658
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• 2004

In this study, we introduced the spiral pipe nailing system (refer as SPN system) with self drilling method, can apply to ground which is hard to keep shape of bore hole, and performed limit equilibrium analysis with simplilied trial wedge method while length ratio and bond ratio were altered to evaluate slope stability considered of tensile strength and bending stiffness. A newly soil nailing system named as the SPN system is respected to reduce displacement of nail and increase global slope stability. And effects of various factors related to the design of the SPN system, such as the type of drilling method and the bit, are examined throughout a series of the displacement-controlled field pull-out tests. 6 displacement-controlled field pull-out tests are performed in the present study and the volume of grouting arc also evaluated based on the measurements. In addition, short-term characteristics of pull-out deformations of the newly proposed SPN system are analyzed and compared with those of the general soil nailing system by carrying out the displacement-controlled field pull-out tests.

• 대한수학교육학회지:수학교육학연구
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• 제27권4호
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• pp.833-855
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• 2017

본 연구는 삼각함수 각의 크기를 표현하기 위해 라디안 단위를 새로 도입하는 이유로서 호의 길이를 이용한 각의 측도라는 호도법의 의미와, 삼각함수의 정의역이 일반각을 나타내는 실수로 확장된 이유를 재조명하고자 한다. 이를 위해 라디안 개념의 다각적인 교수학적 분석을 하고자, 역사적, 수학적, 응용수학적 분석을 수행하였다. 이를 통해 첫째, 호도법은 각도에 내재된 본질이고, 라디안은 원주율(${\pi}$)과 밀접한 이론적이고 절대적인 단위이며, 삼각함수를 실함수로 함을 밝혔다. 둘째, 라디안은 동심원에서 비와 비례 관계의 공변성을 거쳐 불변성을 인식하도록 할 것, 라디안으로 표현한 코사인과 사인의 직교성이 임의의 함수의 급수 표현을 가능하게 함, 라디안은 호의 길이를 반지름으로 측도하는 가장 단순화한 표준임을 인식하도록 할 것, 분할 전략을 통해 육십분법과의 연결성을 찾을 수 있음을 밝혔다. 셋째, 각과 각도의 구별로, 라디안 단위의 생략 여부에 대한 정당화와, 호와 반지름 사이의 곱셈 관계 전략이 필요함을 밝혔다. 이로써 도출한 교수학적 시사점은 라디안 개념의 유용성과 가치를 드러내고, 호도법의 실질적인 지도에 기여할 수 있다.