• Structural Engineering and Mechanics
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• 제12권1호
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• pp.1-16
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• 2001

A reliable and accurate method has been developed to predict the flexural deformation response of structural concrete members subject to service load. The method that has been developed relates the extent of concrete cracking, measured as a function of the magnitude of applied moment in a member, to the reduction in the effective moment of inertia of cracked reinforced concrete members under service load conditions. The ratio of the area of the moment diagram where the moment exceeds the cracking moment, to the total area of the moment diagram for any loading, provides the basis for the calculation of the effective moment of inertia. This ratio also represents mathematically a probability of crack occurrence. Verification of this method for the determination of the effective moment of inertia has been achieved from an experimental test program, and has included beam tests with different loading configurations, and shear wall tests subjected to a range of vertical and lateral load levels. Further verification of this method has been made with reference to the experimental investigation of other recently published work.

• 대기
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• 제29권2호
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• pp.227-239
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• 2019

This paper reviews various bulk-type cloud microphysics parameterizations (BCMPs). BCMP, predicting the moments of size distribution of hydrometeors, parameterizes the grid-resolved cloud and precipitation processes in atmospheric models. The generalized gamma distribution is mainly applied to represent the hydrometeors size distribution in BCMPs. BCMP can be divided in three different methods such as single-moment, double-moment, and triple-moment approaches depending on the number of prognostic variables. Single-moment approach only predicts the hydrometeors mixing ratio. Double-moment approach predicts not only the hydrometeors mixing ratio but also the hydrometeors number concentration. Triple-moment approach predicts the dispersion parameter of hydrometeors size distribution through the prognostic reflectivity, together with the number concentrations and mixing ratios of hydrometeors. Triple-moment approach is the most time expensive method because it has the most number of prognostic variables. However, this approach can allow more flexibility in representing hydrometeors size distribution relative to single-moment and double-moment approaches. At the early stage of the development of BMCPs, warm rain processes were only included. Ice-phase categories such as cloud ice, snow, graupel, and hail were included in BCMPs with prescribed properties for densities and sedimentation velocities of ice-phase hydrometeors since 1980s. Recently, to avoid fixed properties for ice-phase hydrometeors and ad-hoc category conversion, the new approach was proposed in which rimed ice and deposition ice mixing ratios are predicted with total ice number concentration and volume.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.571-576
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• 1998

This paper is a part of a research plan aimed at the verification of basic design rules of high-strength concrete columns. A total of 19 slender column specimens were tested to measure secondary moment and stiffness of eccentrically loaded reinforced concrete tied columns. Main variables included in this test program were concrete compressive strength, steel amount, eccentricity, and slenderness ratio. The concrete compressive strength varied from 356kg/$\textrm{cm}^2$ to 951kg/$\textrm{cm}^2$, the longitudinal steel ratios were between 1.13% and 5.51%, and slenderness ratios were 40 and 61. Calculated moment magnification factors and column stiffness based on design codes are higher than the test results for high axial load under small eccentricity, for higher slenderness ratio, for lower longitudinal steel ratio, and for high-strength concrete. The moment magnification method of the current design codes may provide a very conservative design for high-strength concrete slender column.

• Structural Engineering and Mechanics
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• 제18권6호
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• pp.745-757
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• 2004

Lateral-torsional buckling moment resistances of I-shaped stepped beams with continuous lateral top-flange bracing under a single point load on the top flange and negative end moments were investigated. Stepped beam factors and a moment gradient correction factor suggested by Park et al. (2003, 2004) were used to develop new lateral buckling formula for beam designs. From the investigation of finite element analysis (FEA), new lateral buckling formula of beams with singly or doubly stepped member changes and with continuous lateral top-flange bracing subjected to a single point load on top flange and end moments were developed. The new design equation includes the length-to-height ratio factor to account for the increase of lateral-torsional buckling moment resistance as the increase of length-to-height ratio of stepped beams. The calculation examples for obtaining lateral-torsional buckling moment resistance using the new design equation indicate that engineers should easily determine the buckling capacity of the stepped beams.

• Wind and Structures
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• 제16권6호
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• pp.603-616
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• 2013

This study is aimed at formulating an empirical equation for the across-wind fluctuating moment and spectral density coefficient, which are needed to estimate the across-wind dynamic responses of tall buildings, as a function of the side ratios of buildings. In order to estimate an empirical formula, wind tunnel tests were conducted on aero-elastic models of the rectangular prisms with various aspect and side ratios in turbulent boundary layer flows. In this paper, criteria for the across-wind fluctuating moment and spectral density are briefly discussed and the results are analyzed mainly as a function of the side ratios of the buildings. Finally, empirical formulas for the across-wind fluctuating moment coefficient and spectral density coefficient according to variation of the aspect ratio are proposed.

• Structural Monitoring and Maintenance
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• 제5권4호
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• pp.445-461
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• 2018

The aim of this research is to evaluate the effects of the number of spans, height of spans, number of floors, height of floors, column to beam moment of inertia ratio, and plastic joints distance of beams from columns on the ductility of moment frames. For the facility in controlling the ductility of the frames, this paper offers a simple relation instead of complex equations of different codes. For this purpose, 500 analyzed and designed frames were randomly selected, and their ductility was calculated by the use of nonlinear static analysis. The results cleared that the column-to-beam moment of inertia ratio had the highest effect on ductility, and if this relation was more than 2.8, there would be no need for using the complex relations of codes for controlling the ductility of frames. Finally, the ductility of the most frames of this research could be estimated by using the combination of genetic algorithm and artificial neural networks properly.

• 한국수자원학회논문집
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• 제50권3호
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• pp.211-221
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• 2017

수문통계분야에서는 극치 사상을 해석하기 위해 generalized extreme value (GEV), generalized logistic (GLO), Gumbel (GUM) 모형과 같은 다양한 극치분포들을 사용하여 왔다. 특히 우리나라 강우 사상의 경우 다양한 극치분포 모형 중 GEV 분포와 Gumbel 분포가 비교적 적합한 것으로 알려져 있지만 하나의 형상매개변수를 가지고 있어 각 분포 모형이 나타낼 수 있는 통계적 특성에 한계를 가지고 있다. 이러한 점에서 두 개의 형상매개변수를 가지고 있어 분포 모형이 나타낼 수 있는 통계적 특성의 범위가 넓은 분포의 적용이 필요하다. 이에 본 연구에서는 두 개의 형상매개변수를 가지고 있어 다양한 통계적 특성을 표현할 수 있는 Burr XII 분포와 우리나라 620개 지점의 강우자료의 무차원 L-moment 비를 이용하여 우리나라 강우자료의 수문학적 적용성을 검토하였다. 이를 위해 Burr XII 분포의 L-moment ratio인 L-skewness와 L-kurtosis를 유도하고 그 관계식을 이용하여 L-moment diagram을 작성하고 620개 지점이 해당 영역에 포함되는 정도를 검토하여 그 적용성을 살펴보았다. 그 결과 L-skewness가 L-kurtosis보다 상대적으로 큰 한강 유역에 해당하는 지점들에 대한 Burr XII 분포의 적용성이 우수한 것으로 나타났으며, 이는 일반적으로 많이 사용되는 GEV 또는 Gumbel 분포를 대체할 수 있는 분포가 될 가능성을 보였다고 할 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.241-248
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• 2001

The ductility of circular hollow reinforced concrete columns with one layer of longitudinal and spiral reinforcement placed near the outside face of the section and the steel tube placed on the inside face of the section is investigated. Such hollow sections are confined through the wall thickness since the steel tube is placed. The results of analytical moment-curvature analyses for such hollow sections are compared with those for the circular section with the sane diameter. In this study, moment-curvature analyses are conducted with Mandel's confined concrete stress-strain relationship in which the effect of confinement is to increase the compression strength and ultimate strain of concrete. The moment-curvature analyses confirmed that the ductility is primarily influenced on the ultimate strain. The variables influenced on the ultimate strain is the ratio and yield strength of confining reinforcement and the compression strength for confined concrete. From this ultimate strain - the transverse reinforcement ratio relationship, the transverse reinforcement ratio for circular hollow reinforced columns with confinement is proposed. The proposed transverse reinforcement ratio is confirmed by experimental results.

• 대한기계학회논문집
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• 제14권6호
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• pp.1509-1514
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• 1990

본 연구에서는 비압축성 유체가 온도의 영향을 받아 변화하는 경우에 대한 시 일링 간극내에서의 압력분포를 유한차분법을 이용하여 해석하였다. 여러기서 얻어진 결과를 이용하여 시일의 축력과 모멘트를 해석함으로써 시일의 동적 불안정성에 대하 여 논하였다. 이 때 기계평면시일의 형상은 코닝이 있고, 시일의 중심축이 경사진 경우를 고려하였다.

• 정보처리학회논문지B
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• 제9B권4호
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• pp.501-508
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• 2002

본 논문에서는 영상 내에 존재하는 객체영역의 컬러비와 모멘트를 이용한 영상검색을 제안한다. 객체는 영상의 중심에 위치한다는 가설 하에 미리 정의한 중심영역의 우세컬러를 기반으로 수평-수직 투영을 이용하여 객체영역과 배경영역을 분할함으로써 최적의 공간정보를 획득한다. 또한 영상 내 객체의 회전 및 크기에 불변한 특성을 가지기 위해 컬러비와 모멘트를 특징정보로 이용하며 유사성 측정은 컬러 히스토그램의 구간별 연관성을 고려하기 위해 변형된 히스토그램 인터섹션을 이용한다. 실험결과 제안한 방법이 기존의 영역분할에 의한 방법보다 효율적인 결과를 보였다.