• Computers and Concrete
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• 제6권3호
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• pp.203-223
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• 2009

Regression analysis (RA) can establish an explicit formula to predict the strength of High-Performance Concrete (HPC); however, the accuracy of the formula is poor. Back-Propagation Networks (BPNs) can establish a highly accurate model to predict the strength of HPC, but cannot generate an explicit formula. Genetic Operation Trees (GOTs) can establish an explicit formula to predict the strength of HPC that achieves a level of accuracy in between the two aforementioned approaches. Although GOT can produce an explicit formula but the formula is often too complicated so that unable to explain the substantial meaning of the formula. This study developed a Backward Pruning Technique (BPT) to simplify the complexity of GOT formula by replacing each variable of the tip node of operation tree with the median of the variable in the training dataset belonging to the node, and then pruning the node with the most accurate test dataset. Such pruning reduces formula complexity while maintaining the accuracy. 404 experimental datasets were used to compare accuracy and complexity of three model building techniques, RA, BPN and GOT. Results show that the pruned GOT can generate simple and accurate formula for predicting the strength of HPC.

• 한국구조물진단유지관리공학회 논문집
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• 제4권2호
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• pp.151-158
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• 2000

A study on the strength of steel tubular column filled with concrete under cocentrically compressed load is presented in this paper. This paper is structured as follows. The first section briefly discusses the M-N relationship formula derived for CFT, highlighting the additional moment effect. Next, the simple superposed method used to generate the strength formula of CFT loaded concentrically is described. In the final portion of this paper, the presented formula is compared to experimental data reported. The applicability of CFT strength formula presented here is limited somewhat by scope of concrete strength but can predict the strength of CFT simply and rapidly. The objective of this paper is to approach the strength of CFT theoretically and to examine the feasibility of presented formula.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.356-361
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• 1994

From the previous experimental test results, it has shown that shear that shear strength in lightweight concrete beams was about 85% on that in normal concrete beams. It is speculated that shear connectors in composite beams of steel and lightweight concrete associated with the longitudinal shear strength decrease more in strength than those in normal concrete. So this paper, as a study on strength of shear connectors in composite beams of steel and lightweight concrete slabs, has a purpose to compare the strength formula resulted from the push-out test of thirteen solid slab and four deck Plate slab with the established ones, and then to suggest a proper strength formula of the shear connectors. The established strength formula of the shear connectors is prescribed for $P_ps = 0.50A_s . \sqrt{f_C . E_C}$by AISC coed, but from the experimental test results the strength values of the shear connectors in lightweignt concrete slabs shows about 70% on those of the shear connectors in normal concrete slabs by AISC code. Therefore, as a strength formula this paper suggests to multiply the established strength formula by reduction factor$(\varphi=0.7)$.

• 한국해양공학회지
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• 제34권2호
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• pp.97-109
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• 2020

In this study, ultimate strength characteristics of clamped sandwich panels with metal faces and an elastic isotropic core under combined in-plane compression and lateral pressure loads are investigated to verify the applicability of the ultimate strength design formula for ship structures. Alternative elastomer-cored steel sandwich panels are selected instead of the conventional bottom stiffened panels for a Suezmax-class tanker and then the ultimate strength characteristics of the selected sandwich panels are examined by using nonlinear finite element analysis. The change in the ultimate strength characteristics due to the change in the thickness of the face plate and core as well as the amplitude of lateral pressure are summarized and compared with the results obtained by using the ultimate strength design formula and nonlinear finite element analysis. The insights and conclusions developed in the present study will be useful for the design and development of applications for sandwich panels in double hull tanker structures.

• Journal of Yeungnam Medical Science
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• 제13권2호
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• pp.251-260
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• 1996

To evaluate the effect of low lactose special formula (MF-1) for the treatment of acute diarrhea, we studied thirty nine infants who were admitted with acute diarrhea to the Department of Pediatics, Yeungnam University Hospital. 39 infants of under 6 months of age who had been fed on formula feeds were randomly allocated to receive either a diluted regular formula milk or a low lactose special formula. Each infant received intravenous rehydration during fasting for 6-12 hours. Group 1 (n=15) was fed half strength of regular formula (80-100cc/kg/day) for the first 24 hours, three quarters strength formula (100-120cc/kg/day) for the next 24 hours, and continued feeding with the full strength regular formula milk. Group 2 (n=24), who fed the same amount of milk as Group 1, continued feeding with the full strength low lactose special formula from the start of feeding. Male to female sex ratio was 1.6 to 1. The characteristics of infants on admission were comparable in the age, the duration of diarrhea and the stool frequency before admission, the degree of dehydration. There were no significant differences in the duration of hospitalization, changes in stool weight and stool frequency after admission between two groups.(p>0.05) The Body weight and skin fold thickness were increased in group 2 who fed low lactose formula, but those who fed diluted regular formula showed reduction of body weight and skin fold thickness ($64.2{\pm}51.4g$ vs $-11.4{\pm}52.2g$, $0.6{\pm}0.8mm$ vs $-0.1{\pm}0.3mm$ respectively) during hospitalization. (p<0.05) We conclude that low lactose special formula milk can be recommended instead of diluted regular formula for acute diarrhea treatment in infants.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.189-194
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• 2001

In this study, ultimate strength of concrete deep beams with an opening is predicted by using Strut-and-Tie Model with a new effective compressive strength. First crack occurs around an opening by stress concentration due to geometric discontinuity. This results in decreasing ultimate strength of deep beams with an opening compared with general deep beams. With fundamental notion that ultimate strength of deep beam with an opening decreases as a result of reduction in effective compressive strength of a concrete strut, an equivalent effective compressive strength formula is proposed in order to reflect ultimate strength reduction due to an opening located in a concrete strut. An equivalent effective compressive strength formula which can reflect opening size and position is added to a testified algorithm of predicting ultimate strength of concrete deep beams. Therefore, ultimate strength of concrete deep beam with an opening is predicted by using a simple and rational STM algorithm including an equivalent effective compressive strength formula, not by finite element analysis or a former complex Strut-and-Tie Model

• 한국강구조학회 논문집
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• 제9권3호통권32호
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• pp.391-400
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• 1997

본 연구의 목적은 콘크리트충전 각형강관 기둥의 최대내력을 산정할 수 있는 내력식을 제안하는데 있다. 내력식을 제안하기 위해서 수치해석과 실험을 통해 최대내력를 정량적으로 평가하고 기존의 한계상태설계법의 규준식에 근거하여 적절한 보정방안을 제안하여 콘크리트 충전 각형강관 기둥의 최대내력을 산정할 수 있는 내력식을 제안하고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.763-770
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• 1998

This paper deals with evaluation of bending fatigue strength in SCM415 carburized spur gears. The constant stress amplitude fatigue test is performed by using an electrohydraulic servo-controlled pulsating tester. The S-N curves are obtained and the enhanvement of fatigue strength due to carburized treatment is clarified. In this study the improvement of fatigue strength is assumed to be caused by an increase of both hardness and residual stress and experimental formula has been proposed for the estimation of bending fatigue strength of carburized gears. The effect of surface conditions on the fatigue strength is evaluated quantitatively and it is close to the relative surface condition factor used in the ISO strength rating formula.

• Steel and Composite Structures
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• 제13권5호
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• pp.409-421
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• 2012

Recently, as the height of building is getting higher, the applications of CFST column for high-rise buildings have been increased. In structural system of high-rise building, The RC core and exterior concrete-filled tubular (CFST) column-beam pinned connection is one of the structural systems that support lateral load. If this structural system is used, due to the minimal CFST column thickness compared to that of the CFST column width, the local moment occurred by the eccentric distance between the column flange surface from shear bolts joints degrades the shear strength of the CFST column-beam pinned connections. This study performed a finite element analysis to investigate the shear strength under eccentric moment of the CFST column-beam pinned connections. The column's width and thickness were used as variables for the analysis. To guarantee the reliability of the finite element analysis, an actual-size specimens were fabricated and tested. The yield line theory was used to formulate an shear strength formula for the CFT column-beam pinned connection. the shear strength formula was suggested through comparison on the results of FEM analysis, test and yield lime theory, the shear strength formula was suggested.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.185-188
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• 2005

This study selected three different specified concrete strength types of mixture which were applied to domestic seawater concrete structure and measured compressive strength and chloride diffusion coefficient and composed the formula of prediction model of chloride diffusion coefficient in order to provide the useful data for concrete mix decision of seawater structures. As a result, the formula of prediction model of chloride diffusion coefficient which set W/C and compressive strength as parameters and performed multiplex regression analysis which was based on the mathematical theory was confirmed more reliable than the formula of prediction which was composed existing water-cement ratio function.