• Wind and Structures
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• 제30권1호
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• pp.15-27
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• 2020

This paper reports the study on development and verification of numerical models and analyzes of flow at high speed around structural elements in the shape of a curved pipe (e.g., a fragment of a water slide). Possibility of engineering estimation of wind forces acting on an object in the shape of a helix is presented, using relationships concerning toroidal and cylindrical elements. Determination of useful engineering parameters (such as aerodynamic forces, pressure distribution, and air velocity field) is presented, impossible to obtain from the existing standard EN 1991-1-4 (the so-called wind standard). For this purpose, flow at high speed around a torus and helix, arranged both near planar surface and high above it, was analyzed. Analyzes begin with the flow around a cylinder. This is the simplest object with a circular cross-section and at the same time the most studied in the literature. Based on this model, more complex models are analyzed: first in the shape of half of a torus, next in the shape of a helix.

• 한국환경과학회지
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• 제12권2호
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• pp.195-199
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• 2003

This landscape design is a work for which we selected the square of Sejong Center for the Performing Arts as a object area, drew inhuman factors, and tried to restore them to human environment. This plan assumes that excessive urban environment results from disorder and man can keep it in order and restore it to human environment through the progressive process of speculation. In this plan, we included the least parking space and nearby roads in the object area to maximize the location feature and the symbol of cultural space, and planned that the object area may play its role of open space in the downtown. To grant the symbol of culture space, we established the progressive process of speculation and the relationship of mu, heaven and earth, and culture, geometrically diagrammatized it, combined the circular and rectangular lines derived from it, and suggested a plan. Urban environment will continue to change in the future. However, as long as it is not ensured that the change will progress upward, city would be far from human environment anyhow. Effects to display inhuman space overlooked in the downtown and restore it to human environment for citizen and location for man, should continue.

• 대한기계학회논문집A
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• 제31권10호
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• pp.993-998
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• 2007

To verify the 2D or 3D positioning accuracy of a multi-axes stage is not easy, particularly, in the case the moving path of the stage is not linear. This paper is a study on a measuring method for the curved path accurately. A machine vision technique is used to trace the moving path of two-axes stage. To improve the accuracy of machine vision, a zoom lens is used for the 2D micro moving path. The accuracy of this method depends of the CCD resolution and array align accuracy with the zoom lens system. Also, a further study for software algorithm is required to increase the tracing speed. This technique will be useful to trace a small object in the 2D micro path in real-time accurately.

• 전자공학회논문지B
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• 제33B권3호
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• pp.176-185
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• 1996

Transformin the huge size of drawings into a suitable format for CAD system and recognizng the contents of drawings are the major concerans in the automated analysis of engineering drawings. This paper proposes some methods for text/graphics separation, symbol extraction, vectorization and symbol recognition with the object of applying them to electronic cirucit drawings. We use MBR (Minimum bounding rectangle) and size of isolated region on the drawings for separating text and graphic regions. Characteristics parameters such as the number of pixels, the length of circular constant and the degree of round shape are used for extracting loop symbols and geometric structures for non-loop symbols. To recognize symbols, nearest netighbor between FD (foruier descriptor) of extractd symbols and these of classification reference symbols is used. Experimental results show that the proposed method can generate compact vector representation of extracted symbols and perform the scale change and rotation of extracted symbol using symbol vectorization. Also we achieve an efficient searching of circuit drawings.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.330-333
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• 2002

This study Presents improvement of Precision in the non-contacted laser application measuring techniques. The phase map of deformation obtained by phase shifting method in Electronic Speckle Pattern Interferometry displays the wrapped image by the arctangent function, which is a characteristic of 4-step phase shifting method. To obtain deformation distribution from the results, the wrapped phase map is processed by an unwrapping method. But a previous method cannot apply discontinuous object as like plate with a circular hole to obtain precious deformation distribution To solve this problem, new algorithm is developed and the result is compared with previous method.

• 한국연소학회지
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• 제4권1호
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• pp.105-115
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• 1999

The structure of a non-axisymmetric propane diffusion flame was investigated. Tomographic reconstruction method to convert the line-integrated self-emission data of a fuel-rich diffusion flame with square cross-section was applied to get the spatially reconstructed emission data. Modified Shepp-Logan filter and concentric squares raster were chosen for reconstructing arbitrarily shaped object in this process. Spatially reconstructed emission data were then interpreted to several physical quantities, such as flame edge, FWHM, perimeter and 3-D flame temperature distribution. Necessary assumptions were discussed and the results were interpreted. In comparison with axisymmetric flame, flame edge was developed higher, and sooting region of upstream was broader than in this non-axisymmetric one. At some height, the flame was shrunk very rapidly and finally formed circular cross-section.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.965-970
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• 2001

The object of this research is to evaluate the seismic performance of existing RC bridge piers that were constructed before the adoption of the seismic design provision of Korea Bridge Design Specification in 1992. In this research, adopted test parameters were limited ductile design or non-seismic design, aspect ratio, confinement steel type, loading pattern, lap-spliced ratio for longitudinal reinforcement. This study has been performed to verify the effect of test parameter by quasi-static test. Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteretic curve, envelope curve etc. It has been observed that seismic performance of lap-spliced test specimen, non-seismically designed specimens, was significantly reduced.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.101.3-101
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• 2001

By setting a refractor with a certain angle against the optical axis of the CCD camera lens, the image of a measuring point recorded on the image plane is displaced by the corresponding amounts related to the distance between the camera and the measuring point. When the refractor that keeps the angle against the optical axis is rotated physically at high speed during the exposure of the camera, the image of a measuring point draws an annular streak. Since the size of the annular streak is inversely proportional to the distance between the camera and the measuring point, the 3D position of the measuring point can be obtained by processing the streak. In this paper, for one of the applications of our system, the measurement of a moving surface is introduced. In order to measure the moving surface, multi laser spots are projected on the surface of object. Each position of ...

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.273-277
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• 2002

This paper describes an optimal synthesis method of binary neural network(BNN) for an approximation problem of a circular region and synthetic image having four class using a newly proposed learning algorithm. Our object is to minimize the number of connections and neurons in hidden layer by using a Newly Expanded and Truncated Learning Algorithm(NETLA) based on the multilayer BNN. The synthesis method in the NETLA is based on the extension principle of Expanded and Truncated Learning (ETL) learning algorithm using the multilayer perceptron and is based on Expanded Sum of Product (ESP) as one of the boolean expression techniques. The number of the required neurons in hidden layer can be reduced and fasted for learning pattern recognition.. The superiority of this NETLA to other algorithms was proved by simulation.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.292-299
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• 2005

This paper presents evaluation of seismic design code for AASHTO, Eurocode 8, NZS 3101, and ATC-32 and influence of parameter such as confinement steel ratio, axial force ratio, aspect ratio and longitudinal steel ratio. These seismic design code prescribe confinement steel ratio for appropriate seismic performance which is considered various design parameter. But there is doubt that these parameters are considered rationally in seismic design code. The object of this research is rational evaluation of seismic performance by analysis of existing related experimental research. According to this research, most influence parameter of seismic performance is axial force ratio.