• Computational Structural Engineering
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• v.9 no.1
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• pp.33-45
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• 1996

A general stiffener element which includes transverse shear deformation is formulated using the p-version finite element method. Hierarchic C/sup o/-shape functions, derived from Integrals of Legendre polynomials, are used to define the assembled stiffness matrix of the stiffener with respect to the local reference frame is transformed to the plate reference system by applying the appropriate transformation matrices in order to insure compatibility of displacements at the junction of the stiffener and plate. The transformation matrices which account for the orientation and the eccentricity effects of the stiffener with respect to the plate reference axes are used to find local behavior at the junction of the stiffener and the relative contributions of the plate and stiffener to the strength of the composite system. The results obtained by the p-version finite element method are comared with the results in literatures, especially those by the h-version finite element analysis program, MICROFEAP-II.

• Journal of Educational Research in Mathematics
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• v.27 no.1
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• pp.51-67
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• 2017

Analogical reasoning is a mathematically useful way of thinking. By analogy reasoning, students can improve problem solving, inductive reasoning, heuristic methods and creativity. The purpose of this study is to analyze the analogical reasoning of preservice mathematics teachers while constructing quadratic curves defined by eccentricity. To do this, we produced tasks and 28 preservice mathematics teachers solved. The result findings are as follows. First, students could not solve a target problem because of the absence of the mathematical knowledge of the base problem. Second, although student could solve a base problem, students could not solve a target problem because of the absence of the mathematical knowledge of the target problem which corresponded the mathematical knowledge of the base problem. Third, the various solutions of the base problem helped the students solve the target problem. Fourth, students used an algebraic method to construct a quadratic curve. Fifth, the analysis method and potential similarity helped the students solve the target problem.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.904-907
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• 2002

Optical disk drive device is improved in rotating speed for faster data reading. In the case of CD-ROM, rotating speed is over 10000 rpm in the practical use. As a result of high rotating speed, unexpected effects as like increasing disk fluctuation and acoustic noise are raised by the air friction on the rotating disk and the eccentricity of rotating parts. The overall acoustic noise of running CD-ROM could be classified into two different characterized noise. The first is the structural-borne noise which is generated from vibrating solid body. By the reason, the signal of structural borne noise has very similar to the signal of surface vibrating one. It has dense noise energy at specific frequency region. The other is the air-borne noise which is generated from turbulence or vortex caused by friction between disk and air. The signal of air-borne noise has no dominant peak point at acoustic pressure-frequency domain. The noise energy is widely distributed while comparatively high and large frequency region. The structural-borne noise could be reduced by reducing vibration of structure and in addition it's target reducing frequency is narrow. However the air-borne noise reduction is effectively needed of enclosing method for the noise source located near the disk surface because it is difficult to define target frequency point. In this study, the acoustic noise at driving CD-ROM is classified by the sides of it's character and tried to reduce the overall acoustic noise.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.151-158
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• 2002

Recently, the externally prestressed unbonded steel I-beam bridges have been increasingly built. The mechanical behavior of prestressed steel I-beams which are with external unbonded tendon is different from that of normal bonded PSC beams in a point of that the slip of tendons at deviators and the change of tendon eccentricity occurs, when external loads are applied in external unbonded steel I-beams. The concept of prestressing steel structures has not been widely considered, in spite of long and successful history of prestressing concrete members. In this study, The field experiment on prestressed steel I-beams has been performed in the various aspects of prestressed I-beam including the tend on type and profile.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.5 s.311
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• pp.80-88
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• 2006

In this paper we developed a novel system for automatic detection of mass type breast cancer on dense digital mammogram images. The new approaches presented in this paper are as follows: 1) we presented a method that stably decides the mass center and radius without being affected by image signal irregularity. 2) We developed a radial directional filter that is suitable to process mass image signal. 3) And we developed the multiple feature function based on mass shape spiculation, mass center homogeneity, and mass eccentricity, so as to determine mass-type breast cancer. When the proposed system is applied to dense mammographic images, the true 기arm rate is improved by 10% over a conventional system while the false alarm is increased by 1 per image.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1197-1199
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• 2003

ROCSAT-2 mission is to daily image over Taiwan and the surrounding area for disaster monitoring, land use, and ocean surveillance during the 5-year mission lifetime. The satellite will be launched in December 2003 into its mission orbit, which is selected as a 14 rev/day repetitive Sun-synchronous orbit descending over (120 deg E, 24 deg N) and 9:45 a.m. over the equator with the minimum eccentricity. National Space Program Office (NSPO) is developing a ROCSAT-2 Image Processing System (IPS), which aims to provide real-time high quality image data for ROCSAT-2 mission. A simulated ROCSAT-2 image, based on Level 1B QuickBird Data, is generated for IPS verification. The test image is comprised of one panchromatic data and four multispectral data. The qualification process consists of four procedures: (a) QuickBird image processing, (b) generation of simulated ROCSAT-2 image in Generic Raw Level Data (GERALD) format, (c) ROCSAT-2 image processing, and (d) geometric error analysis. QuickBird standard photogrammetric parameters of a camera that models the imaging and optical system is used to calculate the latitude and longitude of each line and sample. The backward (inverse model) approach is applied to find the relationship between geodetic coordinate system (latitude, longitude) and image coordinate system (line, sample). The bilinear resampling method is used to generate the test image. Ground control points are used to evaluate the error for data processing. The data processing contains various coordinate system transformations using attitude quaternion and orbit elements. Through the qualification test process, it is verified that the IPS is capable of handling high-resolution image data with the accuracy of Level 2 processing within 500 m.

• Steel and Composite Structures
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• v.42 no.5
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• pp.617-631
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• 2022

To study the eccentric compressive performance of the basalt-fiber reinforced recycled aggregate concrete (BFRRAC)-filled circular steel tubular stub column, 8 specimens with different replacement ratios of recycled coarse aggregate (RCA), basalt fiber (BF) dosage, strength grade of recycled aggregate concrete (RAC) and eccentricity were tested under eccentric static loading. The failure mode of the specimens was observed, and the relationship curves during the entire loading process were obtained. Further, the load-lateral displacement curve was simulated and verified. The influence of the different parameters on the peak bearing capacity of the specimens was analyzed, and the finite element analysis model was established under eccentric compression. Further, the design-calculation method of the eccentric bearing capacity for the specimens was suggested. It was observed that the strength failure is the ultimate point during the eccentric compression of the BFRRAC-filled circular steel tubular stub column. The shape of the load-lateral deflection curves of all specimens was similar. After the peak load was reached, the lateral deflection in the column was rapidly increased. The peak bearing capacity decreased on enhancing the replacement ratio or eccentric distance, while the core RAC strength exhibited the opposite behavior. The ultimate bearing capacity of the BFRRAC-filled circular steel tubular stub column under eccentric compression calculated based on the limit analysis theory was in good agreement with the experimental values. Further, the finite element model of the eccentric compression of the BFRRAC-filled circular steel tubular stub column could effectively analyze the eccentric mechanical properties.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.261-271
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• 2006

Many uncertainties affecting to the structural behavior of prestressed concrete (PSC) bridges reinforced with the un bonded external tendons are analyzed on the basis of the analytical method introduced in the companion paper. Many design parameters, which must be considered in design procedure, such as friction slip at the deviators, number of deviators, time-dependent deformations of concrete, relaxation of tendon and influence of loading history in PSC bridges are reviewed, and a lot of valuable results are obtained through this parametric study. In advance, the structural responses according to the external tendon profiles are analyzed to grasp if an optimum tendon profile depends on the applied loading type, and the obtained results show that the most stable structural response is revealed when the locations of deviators are coincident with the loading points.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.247-260
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• 2006

In this paper, an analytical method which can describe the structural behavior of prestressed concrete (PSC) bridges reinforced with the unbonded external tendon is developed. Since the unbonded external tendon is directly installed to the deviators while maintaining a straight configuration, it has a different deformation field from that of concrete and accompanies the secondary effect caused by the change of the primary eccentricity between concrete and external tendon. In advance, the friction slip at the deviators is also taken into consideration on the basis of the force equilibrium between the friction force and the driving force. Through correlation studies between experimental data and analytical results, it is verified that the proposed numerical model can effectively predict the structural behavior of PSC beam bridges with comparative precision.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.75-86
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• 1985

A beam with web opening may reduce the cost of steel and the height of multistory steel buildings. Bower's analysis based on the theory of elasticity and Vierendeel analysis had evaluated the normal stresses around the holes, but these analyses have difficulties for practical uses because of complexity and the limitation for their application. In this study, it is shown that the finite element method, using smaller number of isoparametric elements by taking only a part of the beam which includes the hole, can diminish defects of the above two methods and it may represent more satisfactorily the distribution of the local stress concentration around the hole than the other methods which employed linear elements such as in the analysis by Samuel or Redwood. This study presents the effects of moments, shears, and eccentricities of a hole on the distribution of the normal stresses calculated by using the proposed finite element method. Consequently, it is found that the variations of shear force and hole depth give significant effects on the normal stresses around a hole, while the variations of eccentricities of the hole provide a little effect on them. The regression coefficients resulted from the multiple linear regression may be used for estimating the normal stresses around any arbitrary hole in the web of a beam, since the normal stresses guessed by this regression coefficient equation match well the results by the finite element method except the case of large eccentricity.