• Steel and Composite Structures
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• 제19권6호
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• pp.1561-1580
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• 2015

No significant improvement has been observed on the seismic performance of the ordinary steel reinforced concrete (SRC) columns compared with the reinforced concrete (RC) columns mainly because I, H or core cross-shaped steel cannot provide sufficient confinement for core concrete. Two improved SRC columns by constructing with new-type section steel were put forward on this background: a cross-shaped steel whose flanges are in contact with concrete cover by extending the geometry of webs, and a rotated cross-shaped steel whose webs coincide with diagonal line of the column's section. The advantages of new-type SRC columns have been proved theoretically and experimentally, while construction measures and seismic behavior remain unclear when the new-type columns are joined onto SRC beams. Seismic behavior of SRC joints with new-type section steel were experimentally investigated by testing 5 specimens subjected to low reversed cyclic loading, mainly including the failure patterns, hysteretic loops, skeleton curves, energy dissipation capacity, strength and stiffness degradation and ductility. Effects of steel shape, load angel and construction measures on seismic behavior of joints were also analyzed. The test results indicate that the new-type joints display shear failure pattern under seismic loading, and steel and concrete of core region could bear larger load and tend to be stable although the specimens are close to failure. The hysteretic curves of new-type joints are plumper whose equivalent viscous damping coefficients and ductility factors are over 0.38 and 3.2 respectively, and this illustrates the energy dissipation capacity and deformation ability of new-type SRC joints are better than that of ordinary ones with shear failure. Bearing capacity and ductility of new-type joints are superior when the diagonal cross-shaped steel is contained and beams are orthogonal to columns, and the two construction measures proposed have little effect on the seismic behavior of joints.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1514-1519
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• 1999

This paper presents two flexible alternatives to the decoupled load flow(DCL) method. The proposed load flow methods can improve the convergence profiles of the DCL by reflecting in part the effects of the off-diagonal terms in the Jacobian at minimal costs. They can improve the convergence characteristics especially when the power system operating states deviate from the conditions required for stable convergence of the DCL and the P-Q coupling becomes significant. Two algorithms are obtained from the expression of the full Newton-Raphson load flow (NRL) method by successively diminishing the effects of the off-diagonal submatrices in the Jacobian. In the process of simplification, the Neuman series expansion is utilized. Test results show promising performances of the proposed algorithms in their convergence characteristics both in number of iterations and overall convergence speeds. Proposed algorithms are expected to provide flexible alternatives to the NRL when the DCL experiences convergence problems.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2001년도 추계학술대회 논문집
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• pp.21-24
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• 2001

This study is concerned with the development of efficient p-median approach to nondegenerate cell formation(CF) in group technology(GT) manufacturing. Unlike most of existing CF methodologies allowing degenerate cells or families that contains no parts or machines, this study attempts to find cell configuration where each machine cell contains at least two or more machines processing at least two or more parts so as to fully utilize the similarity in designing and processing parts. Nondegenerate CF seeks to minimize both the exceptional elements outside the diagonal block and the voids within the diagonal block. To find nondegenerate cells, a two-phase p-median methodology is proposed. In phase 1, the classical p-median model is implemented to find initial cells. In phase 2, bottleneck machines and parts are reassigned until no further degenerate cells and families are found. Test results on moderately medium-sized CF problems show the substantial efficiency of the proposed approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.179-181
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• 2005

There is asymmetric in horizontal and vertical side of PDP cell. Every vertical line has BM(Black Mask) to improve luminance contrast. When error diffusion is processed in PDP system, these problems make an error bigger. In 4 inch PDP system, every red, green, blue color of test pattern is presented and each luminance is measured. That is called horizontal(H), diagonal right(R), diagonal left(L) and vertical(V). In red channel, high luminance descending order is V-H-R-L. In green channel, V-H-L-R. In blue channel, V-M-R=L. After average luminance of each direction is calculated. new weighted error diffusion(Weighted ED) is proposed. In digital image signal processing, the error in weighted ED is differ from ED's. The image of weighted ED is more less error compare to conventional ED and close to original image. As the gray level linearity and big size panel is adopted, weighted ED could produce good image.

• Computers and Concrete
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• 제10권2호
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• pp.173-196
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• 2012

Experimental results of cyclic reversed lateral force test on a two-story reinforced concrete shear wall sub-assemblage are simulated analytically by using the PERFORM-3D program. A comparison of experimental and analytical results leads to the following conclusions: (1) "Shear Wall" and "General Wall" models with "Concrete shear" cannot simulate the pinching phenomena due to shear and show larger amounts of inelastic energy absorption than those in the experiment. (2) Modeling a story-height wall by using two or more "General Wall" elements with "Diagonal shear" in the vertical direction induces the phenomenon of swelling-out at the belly, leading to the erroneous simulation of shear behaviors. In application to tall building structures, it is recommended to use one element of "General Wall" with "Diagonal shear" for the full height of a story. (3) In the plastic hinge area, concrete deformations of analytical models overestimate elongation and underestimate shortening when compared with experimental results.

• 음성과학
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• 제13권4호
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• pp.177-186
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• 2006

In an effort to enhance the quality of feature vector classification and thereby reduce the recognition error rate of the speaker-independent speech recognition, we employ the Mahalanobis distance in the calculation of the similarity measure between feature vectors. It is assumed that the metric matrix of the Mahalanobis distance be diagonal for the sake of cost reduction in memory and time of calculation. We propose that the diagonal elements be given in terms of the variations of the feature vector components. Geometrically, this prescription tends to redistribute the set of data in the shape of a hypersphere in the feature vector space. The idea is applied to the speech recognition by hidden Markov model with fuzzy vector quantization. The result shows that the recognition is improved by an appropriate choice of the relevant adjustable parameter. The Viterbi score difference of the two winners in the recognition test shows that the general behavior is in accord with that of the recognition error rate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.325-328
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• 2006

Joint structures of composite truss bridges can have the same details for the connection between diagonal members and upper concrete slab as the connection between diagonal members and lower concrete slab. Adequate connection details should be decided according to design codes, constructibility, and economical evaluation. It is necessary to clarify the design check items and load transferring mechanism because combined external loads on composite truss bridges are concentrated at the joints. Joints with gusset plates and stud connectors are applied and complicated joint details may arise some problems in construction. This paper deals with experimental evaluation of the joints in composite truss bridges and proper design provisions were investigated to enhance the details. Push-out test specimens with group studs were fabricated and the effects of grouping and bent studs were studied.

• Structural Engineering and Mechanics
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• 제19권3호
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• pp.237-260
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• 2005

This paper presents an experimental as well as a numerical analysis of the in-plane shear behaviour of hollow, $870{\times}840{\times}100mm$ masonry walls, externally strengthened with FRP composites. The experimental approach is devoted to the evaluation of the effectiveness of different composite strengthening configurations and the methodology consists in the diagonal compression of masonry walls. The numerical study assesses the stress and strain state distribution in the unreinforced and strengthened panels using a commercial finite element code. The effect of FRP reinforcement on the masonry behaviour and the capability of modelling to forecast a representative failure mode of the unreinforced and reinforced masonry walls is investigated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.601-608
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• 2000

Steel fiber and Polymer are used widely for the reinforcement material of RC structures because of its excellence of durability, serviceability as well as mechanical properties. Polymer-Steel fibrous high strength concrete beam's input ratio are 1.0%. The shear span-to-depth ratio are 1.5, 2.8 and 3.6, compressive strength of specimens 320kg/㎠, 436kgf/㎠ and 520kgf/㎠ in 28 days. The static test was carried out to measure the ultimate load, the initial load of flexural crack and of diagonal crack, from which crack patte군 and fracture modes are earned. Also, stress-strain, load-strain and load-deflection are examined during the test cracks(shear crack, flexural crack, and diagonal tension crack), when the load values are sketched according to the growth of crack. Result are as follows; (1) The failure modes of the specimens increase in rigidity and durability in accordance with the increase of mixing steel fiber and polymer. (2) The load of initial crack was the same as the theory of shear-crack strength (3) Polymer-Steel fibrous high strength concrete beams have increased the deflection and strain at failure load, improving the brittleness of the high strength concrete. (4) In this result of study, an additional study need to make a need formular because the study is different from ACI formular and Zsutty formular.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.139-146
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• 2002

A analysis of crack behavior in RC member was performed by nonlinear finite element method. Two crack models were used in F.E.M.(finite element method): one was FCM (the fixed crack model) and the other was RCM (the rotated crack model). Based on parametric study, the ratio of shear steel, strength of concrete, and a/d(shear span/effective depth) were compared with test results of references. According to the test results, when the member behavior was affected by the shear or diagonal tension, RCM was reasonable. However, when the behavior was affected by the flexibility, FCM was more appropriate. In addition, each crack model behavior for the change of shear steel ratio, the increase of strain energy was constant in FCM, but it was different in RCM because of diagonal crack distribution and crack width. Since the strength of concrete is affected not only by shear but also by flexural strength, each crack model behavior yields similar results.