• Steel and Composite Structures
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• v.5 no.2_3
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.159-168
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• 2005

An improved stability design method for beam-columns of plane frames is proposed based on system buckling analysis and second-order elastic analysis. For this, the tangent stiffness matrix of beam-column elements is first derived using stability functions and a procedure for evaluating effective buckling lengths is reviewed using elastic system buckling analysis. And then the second-order analysis procedure is presented considering $P-\Delta$ effects and is compared with the closed-form solution through numerical examples. Design examples showing the validity of the proposed method we presented and their numerical results are compared with those obtained from the conventional stability design methods. Finally some useful conclusions are drawn.

• East Asian mathematical journal
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• v.27 no.1
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• pp.51-65
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• 2011

In the paper, we study questions on classical solvability of nonlocal problems for a third-order linear hyperbolic equation in a rectangular domain. The Riemann method is applied to the Goursat problem and solution is obtained in the integral form. Investigated problems are reduced to the uniquely solvable Volterra-type equation of second kind. Influence effects of coefficients at lowest derivatives on correctness of studied problems are detected.

• Asia pacific journal of information systems
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• v.13 no.3
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• pp.173-193
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• 2003

As the interest in the business-to-business(B2B) electronic commerce is increasing, some companies are participating in the B2B eMarketplaces(electronic marketplaces). The eMarketplace has an effect on the method of B2B transactions or the purchasing performance. The academy and the industry are focused on the cause and the result of this effect. The purpose of this research is to analyze the effects of the relational exchange with eMarketplace on the purchasing performance, considering the supply externality and system integration as intervening variables. This study investigates the second-order effect of eMarketplace in which the degree of improvements in two aspects of purchasing activity(price reduction, purchasing efficiency) depends on the degree of the relational exchange with eMarketplace, namely, the governance of eMarketplace. Our hypotheses on this second order effect were supported. We found that the higher the relational governance, the lower in price reduction, and the better in purchasing efficiency. In more details, the high relational governance lowers the supply externality, and in turn deteriorates the improvement in price reduction. Meanwhile, the high relational governance accelerates the information system integration, and brings the better purchasing efficiency. Our findings suggest that organizations can improve their purchasing activities better if they choose the appropriate eMarketplace governance.

• Computers and Concrete
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• v.2 no.1
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• pp.1-18
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• 2005

This paper presents a study on the effects of localized steel-concrete bond degradation on the flexural behaviour of RC beams. A finite element analysis is undertaken to complete the experimental analysis. The first part deals with an experimental study on beams where bond was removed by using plastic tube at different locations and for various lengths. The flexural behaviour was studied at global scale (load-deflection) and local scale (moment-curvature). The second part, a numerical study using a simplified special finite element (rust element) modelling the rust layer occurring between reinforcement and concrete with corrosion was conducted in order to find the relation between the degree of corrosion and the degradation of the steel-concrete bond. The computed value of the corrosion degree corresponding to the total degradation of bond has been used in a second time to model the tests, in order to evaluate the influence of the loss of bond, the steel cross section reduction, and the combination of both. The results enable to evaluate the influence of the different corrosion effects on the flexural behaviour, according to the length and the location of the corroded zone.

• International Journal of Advanced Culture Technology
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• v.7 no.2
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• pp.179-187
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• 2019

As the globalization process progresses more rapidly and widely, there has been a ever-growing demand for multilingual learning. Compared with the study of Second Language Acquisition, studies on the Third Language and even Multilingual Acquisition have attracted a relatively poor attention. At the same time, considering current educational environments for ethnic colleges and universities, the effects of college English teaching for minority students can be said to have been 'generally poor.' In this situation, when we try to find ways to improve college English studies for minority students most of whom already can speak two languages or even more, it would not be the best idea to keep following the experiences of traditional Second Language Acquisition. It is necessary first to find out whether there are positive or negative effects in acquiring multiple languages, and then to conduct a profound research on L3 (third language and even multilingual) Acquisition in order to employ more efficient teaching methods for multilingual learners. After conducting a Japanese-teaching experiment on two groups of learners with mono-lingual and bilingual backgrounds, it has been found that there is a positive transfer between different languages. In this paper, following the recent research findings on Language teaching for multilingual learners, I try to show with further supports that when it comes to language education for learners with multilingual backgrounds, we should focus on the advantages they may earn in order to conduct more effective language acquisition.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.363-375
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• 2022

Flexural capacity prediction is a challenging problem for externally prestressed concrete beams (EPCBs) due to the unbonded phenomenon between the concrete beam and external tendons. Many prediction equations have been provided in previous research but typically ignored the differences in deformation mode between internal and external unbonded tendons. The availability of these equations for EPCBs is controversial due to the inconsistent deformation modes and ignored second-order effects. In this study, the deformation characteristics and collapse mechanism of EPCB are carefully considered, and the ultimate deflected shape curves are derived based on the simplified curvature distribution. With the compatible relation between external tendons and the concrete beam, the equations of tendon elongation and eccentricity loss at ultimate states are derived, and the geometric interpretation is clearly presented. Combined with the sectional equilibrium equations, a rational and simplified flexural capacity prediction method for EPCBs is proposed. The key parameter, plastic hinge length, is emphatically discussed and determined by the sensitivity analysis of 324 FE analysis results. With 94 collected laboratory-tested results, the effectiveness of the proposed method is confirmed, and comparisons with the previous formulas are made. The results show the better prediction accuracy of the proposed method for both stress increments and flexural capacity of EPCBs and the main reasons are discussed.

• Journal of the Korean Home Economics Association
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• v.32 no.4
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• pp.57-71
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• 1994

The purpose of this research was to study the variables related to the stress and to provide the way of establishing better relationship between aged parents and adult offsprings and the way of effective care-giving. In order to achieve this purpose a survey was conducted by interview using questionaire. The collected data were analyzed by using frequency percentage mean standard deviation factor analysis Pearson's correlation analysis, ANOVA, and stepwise regression analysis. The results of this research were as follows: First The total points of daughter-in-laws' caregicing stress was 38.5 and daughter's caregiving stress was 27.3. Second There were meaningful differences according to living arrangement daughters-in-law age, old mothers' health status. And there were significant. interaction effects among variables of living arrangement and daughters-in-law' age, living arrangement and birth order birth order and old mothers' health status. living arrangement and daughters-in-law' age and old mothers' health status. Third There were meaningful differences according to living arrangement daughter's age. And there were significant interaction effects among variables of living arrangement and daughter's age, daughter's age and birth order, living arrangement and daughter's age and old mothers' health status, living arrangement and birth order and old mothers' health status. Fourth Among daughters-in-law' variables living arrangement age, old mothers' health status have influence on the care-giving stress. Among daughter's variables living arrangement, age, birth order have influence on the care-giving stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.215-224
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• 2000

In order to reduce the variation effects of uncertainties in the engineering environments, new robust optimization method, which considers the uncertainties in design process, is proposed. Both design variables and system parameters are considered as random variables about their nominal values. To ensure the robustness of performance function, a new objective is set to minimize the variance of that function. Constraint variations are handled by introducing probability constraints. Probability constraints are solved by the advanced first order second moment (AFOSM) method based on the reliability theory. The proposed robust optimization method has an advantage that the second derivatives of the constraints are not required. The suggested method is examined by solving three examples and the results are compared with those for deterministic case and those available in literature.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.167-172
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• 1992

To analyze the effects compressive strength of concrete and longitudinal steel ratio on second-order moment of columns, 30tied rein reinforced concrete columns with hinged ends were tested. The 80mm square cross section was used and the amount of eccentricity was 24mm. The compressive strengths of column specimens with slenderness ratios of 10, 60, and 100were 250, 648 and 880kg/$\textrm{cm}^2$, and the longitudinal steel ratios were 1.98%(4-D6) and 3.95%(8-D6). The ratio of ultimate load capacity to that of short column with the same eccentricity (Pu/Pn) was much decreased at high slenderness ratio with increasing the compressive strength of concrete. And the lateral displacement of slender column at the ultimate load was decreased as the strength was increased. These are due to that at high slenderness ratio the load capacity and behavior of column are affected by flexural rigidity. And, it was also found that with increasing steel ratio, the value of Pu/Pn and the lateral displacement at the ultimate load were larger for the same slenderness ratio.