• Structural Engineering and Mechanics
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• 제82권1호
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• pp.1-16
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• 2022

This work elaborately investigates the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the suspended monorail vehicle-guideway system (SMVGS). Firstly, a spatial dynamic analysis model of the SMVGS is established by adopting ANSYS parameter design language. Then, the dynamic interaction between a vehicle with maximum design load and guideway is investigated by numerical simulation and field tests, revealing the vehicle-guideway dynamic features. Subsequently, the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the SMVGS are analyzed and discussed in detail, and the reasonable ranges of several key geometry parameters of the guideway are also obtained. Results show that the vehicle-guideway dynamic responses change nonlinearly with an increase of the guideway span, and especially the guideway dynamic performances can be effectively improved by reducing the guideway span; based on a comprehensive consideration of all performance indices of the SMVGS, the deflection-span ratio of the suspended monorail guideway is finally recommended to be 1/1054~1/868. The train load could cause a large bending deformation of the pier, which would intensify the car-body lateral displacement and decrease the vehicle riding comfort; to well limit the bending deformation of the pier, its cross-section dimension is suggested to be more than 0.8 m×0.8 m. The addition of the track irregularity amplitude has small influences on the displacements and stress of the guideway; however, it would significantly increase the vehicle-guideway vibrations and rate of load reduction of the driving tyre.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.23-28
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• 2006

In this study, the general theory of fractality is discussed to provide a fundamental understanding of fractal geometry applied to heterogeneous material surfaces like pavement surface and rock surface. It is well known that many physical phenomena and systems are chaotic, random and that the features of roughness are found at a wide spectrum of length scales from the length of the sample to the atomic scales. Studying the mechanics of these physical phenomena, it is absolutely necessary to characterize such multi scaled rough surfaces and to know the structural property of such surfaces at all length scales relevant to the phenomenon. This study emphasizes the role of fractal geometry to characterize the roughness of various surfaces. Pavement roughness and rock surface roughness were examined to correlate their roughness property to fractality.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.334-337
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• 1996

This is a paper intended for initial stage of vehicle modeling and design. The needs to determine a variety of vehicle suspension parameters required for initial design has been difficult and time-consuming task. In order to facilitate a concise and efficient presentation of initial vehicle design procedure, this paper uses a mathematical model and physical geometry. Vehicle model consists of dimensions, inertias and mechanical constants. These vehicle model parameters divided into several categories : basic parameters, coefficients and constants, design specification, spring and damper, bush stiffness, stabilizer bar, suspension geometry, tire, and vehicle weights of various design condition. This paper uses a vehicle design fundamental (VDF) program running under Windows 95 graphical interface. The features of VDF will be briefly outlined in this paper.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.674-677
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• 2003

This work presents a method of point-to-surface assignment for 3D inspection of solder pastes on PCB. A bounding box enclosing the solder paste tightly on all sides is introduced to avoid incorrect point-to-surface assignment. The shape of bounding box for solder paste brick is variable according to geometry of measured points. The surface geometry of the bounding box is obtained by using five peaks selected from the histogram of normalized gradient vectors for measured points. By using the bounding box enclosing the solder paste. the task of point-to-surface assignment is successfully executed. Subsequently, the geometrical features are obtained via surface fitting.

• International Journal of Contents
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• 제5권4호
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• pp.55-61
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• 2009

In this paper, we propose a hierarchical method for segmenting a given 3D mesh, which hierarchically clusters sharp vertices of the mesh using the metric of geodesic distance among them. Sharp vertices are extracted from the mesh by analyzing convexity that reflects global geometry. As well as speeding up the computing time, the sharp vertices of this kind avoid the problem of local optima that may occur when feature points are extracted by analyzing the convexity that reflects local geometry. For obtaining more effective results, the sharp vertices are categorized according to the priority from the viewpoint of cognitive science, and the reasonable number of clusters is automatically determined by analyzing the geometric features of the mesh.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.301-302
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• 2006

In this paper, the possibilities of the Infra-red sensor in sensing and control of the bead geometry in the automated welding process are presented. Infra-red sensor is a well-known method to deal with the problems with a high degree of fuzziness so that the sensor is employed to build the relationship between process variables and the quality characteristic the proposed above respectively. Based on several neural networks, the mathematical models are derived from extensive experiments with different welding parameters and complex geometrical features. The developed system enables to select the optimal welding parameters and control the desired weld dimensions during arc welding process.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제5권1호
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• pp.1-12
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• 2001

Generating fractal images by graphing calculators such as TI_92 combines several important features, which convey the excitement of a living, changing mathematics appropriate to secondary or post-secondary students. The topic of fractal geometry can be illustrated using natural objects such as snowflakes, leaves and ferns. These complex and natural forms are often striking fantastic and beautiful. The examples highlight the fact that complex, natural behaviors can result from simple mathematical rules such as those embodied in iterated function systems(IFS). The visual splendor beauty of fractals, in concert with their ubiquity in nature, revels the intellectual beauty of nonlinear mathematics in a compelling way. The window is now open for students to experience and explore some of the wonder of fractal geometry.

• 한국수학교육학회지시리즈A:수학교육
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• 제38권1호
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• pp.1-14
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• 1999

It has already been fifty years since the Korean peninsula was divided into two nations, South and North Korea. Owing to forming different political and social structures with each other, we can conjecture that there are much heterogeneity in education. On the assumption that education plays important role in coming to an accommodation and in restoring homogeneity of the Korean race after unification, we consider the investigation of the contents of mathematics text-book of secondary schools as a meaningful research to make provision against unification. In this paper, we shall investigate the learning contents, and the teaming substances and sequences in mathematics of secondary schools between South and North Korea by falling into four regions; algebra and statistics, analysis and geometry. By grasping the special features of terms, teaming subject matters and learning substances, and clarifying their distinctions, we shall present some reforms measure of distinctions.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.272-279
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• 2002

A common task in assembly modeling is the determination of the position and orientation of a set of components by solving the spatial relationships between them. Assembly models could be constructed at various levels of abstraction. They could be classified into component or geometry-level assembly models. The geometry-level assembly design approach using mating constraints such as against and fits is widely used in the commercial modelers, but it may be very tedious in some cases fur designer. In this paper, we propose a new method to construct an assembly model at the component-level by extracting joint mating features from the kinematics constraints specified between components. The assembly model constructed using the proposed method includes hierarchical and relational assembly models, component/sub-assembly positions and degrees of freedom information. The proposed method is more intuitive and natural way of assembly design and it guarantees the topological robustness of assembly modification such as component replacement and modification.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 2004년도 GIS/RS 공동 춘계학술대회 논문집
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• pp.23-29
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• 2004

GIS 관련 산업이 발전함에 따라, 공간 데이터의 상호 운용성이라는 문제가 제기되었다. 현재, 이러한 문제점을 해결하기 위해 OGC는 공간 데이터 및 GIS에 대한 국제적인 표준을 제시하고 있다. 본 연구에서는 OGC의 Simple Features for OLE/COM 표준 사양을 준수하는 GIS 데이터제공자를 구현하여 기존의 공간 데이터베이스와 Geometry 컴포넌트간 공간 데이터에 대한 상호 운용성을 확인하고자 한다. 더 나아가 공간 데이터베이스와 Geometry 컴포넌트로 이루어지는 GIS S/W 시스템 성능 향상을 위한 GIS 데이터제공자 기반의 버퍼관리기법에 대한 설계 및 구현을 하고, 이에 대한 성능 테스트를 하고자 한다. 또한, GIS 데이터제공자 및 버퍼관리기법을 구현하여 앞으로 GIS 데이터제공자 기반의 황용 방안을 제시하고자 한다.