• 대한수학회보
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• 제61권2호
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• pp.355-379
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• 2024

In this paper, we establish the curvature estimates for a class of curvature equations with general right hand sides depending on the gradient. We show an existence result by using the continuity method based on a priori estimates. We also derive interior curvature bounds for solutions of a class of curvature equations subject to affine Dirichlet data.

• Computers and Concrete
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• 제16권2호
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• pp.191-207
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• 2015

It is generally accepted that, in the interest of safety, it is essential to provide a minimum level of flexural ductility, which will allow energy dissipation and moment redistribution as required. If one wishes to be uniformly conservative across all of the design variables, curvature ductility and moment redistribution factor should be calculated using a probabilistic method, as is the case for other design parameters in reinforced concrete mechanics. In this study, simple expressions are derived for the evaluation of curvature ductility and moment redistribution factor, based on the concept of demand and capacity rotation. Probabilistic models are then derived for both the curvature ductility and the moment redistribution factor, by means of central limit theorem and through taking advantage of the specific behaviour of moment redistribution factor as a function of curvature ductility and plastic hinge length. The Monte Carlo Simulation (MCS) method is used to check and verify the results of the proposed method. Although some minor simplifications are made in the proposed method, there is a very good agreement between the MCS and the proposed method. The proposed method could be used in any future probabilistic evaluation of curvature ductility and moment redistribution factors.

• 척추신경추나의학회지
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• 제5권1호
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• pp.31-40
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• 2010

Objectives: To investigate the change of the cervical spine curvature after whiplash injury. Methods: Clinical study carried out in 46 patients who already had neck pain and took a cervical lateral X-Ray in Jaseng Oriental hospital. these patients had whiplash injury whitin one year. We followed up the cervical lateral X-Ray after that. Cervical spine curvature was measured using four measuring method. Type of cervical spine curvature was analyzed by Jochumsen method, Ishihara Index. T-test was used. Results: By Jackson's Angle and Cobb's angle, it is tend to be more Iordotic curvature after whiplash injury. In Jochumsen method, Ishihara Index the cervical spine curvature was significantly increased their Iordotic angle(P<0.05). Conclusion: The results suggest that after whiplash injury, patients cervical curvature change more Iordortic curve.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1173-1182
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• 1998

A throughflow analysis program for axial flow turbines is constructed, which can handle not only the two-dimensional multi-streamline (streamline curvature) method but also the one-dimensional mean line method. Calculations are performed for single stage and multi-stage axial flowturbines. For a wide operating range, the performance and flow field calculated by the present streamline curvature method are close enough to the test data. It is also revealed for the single stage turbine that the present analysis leads to far better correspondence with the experiment than other researchers" throughflow analyses. A special focus is put on the comparison of the results between the streamline curvature analysis and the mean line analysis. It is found that the mean line analysis can not predict the performance for highly off-designed conditions as accurately as the streamline curvature method, which shows the importance of considering the spanwise variation of loss and flow.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.482-486
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• 2009

Scale-invariant feature is an effective method for retrieving and classifying images. In this study, we analyze a scale-invariant planar curve features for developing 2D shapes. Scale-space filtering is used to determine contour structures on different scales. However, it is difficult to track significant points on different scales. In mathematics, curvature is considered to be fundamental feature of a planar curve. However, the curvature of a digitized planar curve depends on a scale. Therefore, automatic scale detection for curvature analysis is required for practical use. We propose a technique for achieving automatic scale detection based on difference of curvature. Once the curvature values are normalized with regard to the scale, we can calculate difference in the curvature values for different scales. Further, an appropriate scale and its position are detected simultaneously, thereby avoiding tracking problem. Appropriate scales and their positions can be detected with high accuracy. An advantage of the proposed method is that the detected significant points do not need to be located in the same contour. The validity of the proposed method is confirmed by experimental results.

• 대한전기학회논문지:전력기술부문A
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• 제48권3호
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• pp.313-320
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• 1999

The Lane-Curvature Method(LCM) presented in this paper is a new local obstacle avoidance method for indoor mobile robots. The method combines Curvature-Velocith Method(CVM) with a new directional method called the Lane Method. The Lane Method divides the environment into lanes taking the information on obstacles and desired heading of the robot into account ; then it chooses the best lane to follow to optimize travel along a desired heading. A local heading is then calculated for entering and following the best lane, and CVM uses this heading to determine the optimal translational and rotational velocity space methods, LCM yields safe collision-free motion as well as smooth motion taking the dynamics of the robot Xavier, show the efficiency of the proposed method.

• 대한추나의학회지
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• 제5권1호
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• pp.151-161
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• 2004

Objectives : To investigate and compare the curvature of the cervical spine of the patients with whiplash and insidious onset neck pain. Method : Clinical study carried out in 33 insidious onset neck pain outpatients and 34 whiplash onset neck pain inpatients in Conmaul Oriental Hospital. Cervical spine curvature was measured using five measuring Methods. Type of cervical spine curvature was analyzed by Jochumsen method. Ishihara Index. T-test was used to compare the cervical spine angle of the two groups. Results : The prevalence of 'straight' and 'kyphotic' cervical spines was 46.5% in the insidious onset cases and 26.47% in the whiplash onset cases. In Jackson's angle, Jochumsen method, Ishihara Index, and Park's method, angle of the Cervical spine curvature was significantly lower in the insidious onset cases. (P<0.01) Conclusion : The results suggest that the cervical spine of neck pain patients is 'straight' and 'kyphotic' and more significant in insidious onset cases.

• 한국정보처리학회논문지
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• 제3권6호
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• pp.1616-1623
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• 1996

일반적으로 3차원 물체의 인식이나 모델링을 하기 위해서는 물체의 모양을 표현 하는 방법이 필요하다. 실루엣이미지와 같은 2차원인 경우 물체의 모양을 나타내는 경계선상의 정점 추출은 2차원 곡률함수를 이용하지만, 3차원의 경우는 물체표면의 곡률을 계산할 수 있는 3차원 곡률함수가 없기 때문에 어려운 점이 있다. 따라서 본 논문에서는 2차원 곡률원리와 최소자승법을 이용하여 근사화된 3차원 물체의 표면 곡 률값과 장점을 효과적으로 구할 수 있는 새로운 방법을 제시하였다.

• 한국군사과학기술학회지
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• 제15권6호
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• pp.779-785
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• 2012

In this paper, we have analyzed the curvature effects of the finite FSS(frequency selective surface) using the 3-D method of moment using the BiCGSTab algorithm as an iterative method. To validate the analysis method in this paper, we compared the RCS(radar cross section) of PEC(perfect electric conductor) sphere with theoretical results and it shows well agreements. The tripole slot FSSs which have many application in military were selected for the investigation of curvature effect and RCS as a frequency characteristics were observed with the variation of the curvature rate. Simulation results shows that curvature effect can significant effect the passband frequency and bandwidth of FSS. We suggest that the curvature effect must be considered at the stage of design FSS application like FSS radome.

• 호남수학학술지
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• 제28권3호
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• pp.399-407
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• 2006

In this paper, we consider the problem of achieving a prescribed scalar curvature on warped product manifolds according to fiber manifolds with zero scalar curvature.