• Structural Engineering and Mechanics
• /
• v.33 no.2
• /
• pp.137-158
• /
• 2009

This paper investigates the behavior of reinforced concrete (RC) circular columns under combined loading including torsion. The main variables considered in this study are the ratio of torsional moment to bending moment (T/M) and the level of detailing for moderate and high seismicity (low and high transverse reinforcement/spiral ratio). This paper presents the results of tests on seven columns subjected to cyclic bending and shear, cyclic torsion, and various levels of combined cyclic bending, shear, and torsion. Columns under combined loading were tested at T/M ratios of 0.2 and 0.4. These columns were reinforced with two spiral reinforcement ratios of 0.73% and 1.32%. Similarly, the columns subjected to pure torsion were tested with two spiral reinforcement ratios of 0.73% and 1.32%. This study examined the significance of proper detailing, and spiral reinforcement ratio and its effect on the torsional resistance under combined loading. The test results demonstrate that both the flexural and torsional capacities are decreased due to the effect of combined loading. Furthermore, they show a significant change in the failure mode and deformation characteristics depending on the spiral reinforcement ratio. The increase in spiral reinforcement ratio also led to significant improvement in strength and ductility.

• Nuclear Engineering and Technology
• /
• v.53 no.12
• /
• pp.4072-4079
• /
• 2021

This article presents a study on the state-of-the-art methods for automated radioactive material detection and identification, using gamma-ray spectra and modern machine learning methods. The recent developments inspired this in deep learning algorithms, and the proposed method provided better performance than the current state-of-the-art models. Machine learning models such as: fully connected, recurrent, convolutional, and gradient boosted decision trees, are applied under a wide variety of testing conditions, and their advantage and disadvantage are discussed. Furthermore, a hybrid model is developed by combining the fully-connected and convolutional neural network, which shows the best performance among the different machine learning models. These improvements are represented by the model's test performance metric (i.e., F1 score) of 93.33% with an improvement of 2%-12% than the state-of-the-art model at various conditions. The experimental results show that fusion of classical neural networks and modern deep learning architecture is a suitable choice for interpreting gamma spectra data where real-time and remote detection is necessary.

• Smart Structures and Systems
• /
• v.1 no.4
• /
• pp.385-404
• /
• 2005

The paper presents a model to calculate reinforcement strain using measured crack width in members under applied tension, flexure, and/or shear stress. Crack mapping using a new type of distributed coaxial cable sensors for health monitoring of large-scale civil engineering infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to cyclic combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor's response to strain in the member, and show that magnitude of the signal's reflection coefficient is related to increases in applied load, repeated cycles, cracking, and reinforcement yielding. The effect of multiple adjacent cracks, and signal loss was also investigated. The results shown in this paper are an important step in using the sensors for crack mapping and determining reinforcement strain for in-situ structures.

• Korean Journal of Veterinary Research
• /
• v.60 no.2
• /
• pp.49-54
• /
• 2020

The goal of this study was to determine if there was a difference in leak pressure between esophageal-esophageal anastomosis and esophageal-jejunal anastomosis when using cadaveric porcine tissue. Leak pressures were recorded for esophageal-esophageal anastomosis (Group 1 [control group], n = 7), cranial esophageal-jejunal anastomosis (Group 2, n = 7), and jejunal-caudal esophageal anastomosis (Group 3, n = 6). Each anastomosis was performed using polydioxanone sutures in a simple interrupted pattern. Results were analyzed using one-way analysis of variance. Mean ± SD of the leak pressures for groups 1, 2, and 3 were 46.1 ± 15.9, 36.5 ± 13.6, and 50.9 ± 11.1 mmHg, respectively (p = 0.18). When the results from groups 2 and 3 were combined and compared to that for Group 1, the mean ± SD leak pressures were 46.1± 15.9 and 43.1± 14.2 mmHg, respectively (p = 0.67). These results provide preliminary evidence that the jejunum may be a suitable option for use in esophageal replacement surgery; however, future studies of in vivo factors influencing the integrity of esophageal-jejunal anastomoses, including histologic evaluation of esophageal-jejunal anastomosis healing, are needed.

• Structural Engineering and Mechanics
• /
• v.10 no.6
• /
• pp.517-532
• /
• 2000

A direct output feedback control scheme was recently proposed by the authors for single-story building structures resting on flexible soil body. In this paper, the control scheme is extended to mitigate the seismic responses of multi-story buildings. Soil-structure interaction is taken into account in two parts: input at the soil-structure interface/foundation and control algorithm. The former reflects the effect on ground motions and is monitored in real time with accelerometers at foundation. The latter includes the effect on the dynamic characteristics of structures, which is formulated by modifying the classical linear quadratic regulator based on the fundamental mode shape of the soil-structure system. Numerical result on the study of a $\frac{1}{4}$-scale three-story structure, supported by a viscoelastic half-space of soil mass, have demonstrated that the proposed algorithm is robust and very effective in suppressing the earthquake-induced vibration in building structures even supported on a flexible soil mass. Parametric studies are performed to understand how soil damping and flexibility affect the effectiveness of active tendon control. The selection of weighting matrix and effect of soil property uncertainty are investigated in detail for practical applications.

• Structural Engineering and Mechanics
• /
• v.83 no.4
• /
• pp.435-449
• /
• 2022

Constitutive modeling that could reasonably predict and effectively evaluate the post-peak structural behavior while eliminating the mesh-dependency in numerical simulation remains to be developed for general engineering applications. Based on the previous work, a simple one-dimensional modeling procedure is proposed to predict and evaluate the post-peak response, as characterized by the evolution of localized strain field, of a steel member to monotonically uniaxial tension. The proposed model extends the classic one-dimensional softening with localization model as introduced by (Schreyer and Chen 1986) to account for the localization length, and bifurcation and rupture points. The new findings of this research are as follows. Two types of strain-softening functions (bilinear and nonlinear) are proposed for comparison. The new failure criterion corresponding to the constitutive modeling is formulated based on the engineering strain inside the localization zone at rupture. Furthermore, a new mathematical expression is developed, based on the strain rate inside and outside the localization zone, to describe the displacement field at which bifurcation occurs. The model solutions are compared with the experimental data on four low-carbon cylindrical steel bars of different lengths. For engineering applications, the model solutions are also compared to the experimental data of a cylindrical steel bar system (three steel bars arranged in series). It is shown that the bilinear and nonlinear softening models can predict the energy dissipation in the post-peak regime with an average difference of only 4%.

• International Journal of Concrete Structures and Materials
• /
• v.7 no.4
• /
• pp.273-285
• /
• 2013

An experimental investigation was conducted to compare the shear strength of full-scale beams constructed with chemically-based, self-consolidating concrete (SCC) with conventional concrete (CC). This experimental program consisted of 16 rectangular beams (12 without shear reinforcing and 4 with shear reinforcing in the form of stirrups), 8 beams for each mix design. Additionally, three different longitudinal reinforcement ratios were evaluated within the test matrix. The beam specimens were tested under a simply supported four-point condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (U.S., Australia, Canada, Europe, and Japan) and a shear database of CC specimens. This comparison indicates that chemically-based SCC beams possess comparable shear strength as CC beams.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.50 no.1
• /
• pp.32-38
• /
• 2005

A long-term study initiated in 1989 at San-born Field, Columbia, Missouri, was designed to evaluate the affect of environmental factors, nitrogen application, and crop rotation on soybean (Glycine max [L.] Merr.) seed composition. Soybeans were grown as part of a four- year rotation which included corn (Zea maize L.), wheat (Triticum aestivum L.), and red clover (Trifolium pratense L.). Results from soil tests made prior to initiation of the study and subsequently every five years, were used to calculate application rates of nitrogen, phosphorus, and potassium necessary for target yield of pursuant crops. In the experimental design, nitrogen was applied to one-half of the plot on which the non-leguminous crop, either corn or wheat was grown. Analysis of soybean seed by near infrared reflectance spectroscopy collected over an 11-year period revealed a linear increase in protein and decrease in oil content. Application of nitrogen fertilizer to non-leguminous crops did not have an apparent effect on total protein or oil content of subsequent soybean crop. Analysis of soybean seed proteins by sodium dodecyl sulfate polyacrylamide gel electrophoresis in conjunction with computer­assisted densitometry revealed subtle changes in the accumulation of seed proteins. Immunoblot analysis using antibodies raised against the $\beta-subunit$ of $\beta-conglycinin$ showed a gradual increase in the accumulation of the 7S components during successive years of the experiment. A linear increase in temperature and decrease in rainfall was observed from the onset of data· collection. Higher temperatures during the growing season have been linked to increased protein and diminished oil content of soybean, thus changes observed in this study are possibly related to climatic conditions. However, crop rotation and subsequent changes in soil ecology may contribute to these observed changes in the seed composition.

• Journal of Elementary Mathematics Education in Korea
• /
• v.16 no.2
• /
• pp.185-202
• /
• 2012

This study is focused on the gifted education program, "EEE" of Columbia Public Schools in Missouri. This program is recommended to follow NAGC Pre-K-Grade 12 Gifted programming standards(NAGC, 2010) and Missouri school laws(MDESE, 2012b), but is allowed to run autonomically without any support in a federal or state level. The characteristics of EEE are as follows: ${\cdot}$ emphasizing not only on the cognitive development but also on the social and affective/emotional development of the gifted students ${\cdot}$ encouraging each student's own interest by allowing him/her to select his/her major and minor ${\cdot}$ the variety of classes ${\cdot}$ the call-up class - discriminating from regular classes ${\cdot}$ the interdisciplinary approach - connecting many subjects around the main idea ${\cdot}$ the activity-based learning such as hands-on activities, projects, and simple experiments ${\cdot}$ using the individual activity as well as pair or group activity In special, this paper also contains an example of program about mathematics and suggests some implications for gifted education programs in Korea.

• International Journal of Human Ecology
• /
• v.5 no.2
• /
• pp.13-29
• /
• 2004

Ryff's(1989) psychological well-being measure is used to assess and sometimes compare Korean and American adults, however, there is no information regarding whether its dimensions are psychometrically invariant across, whether its items provide sufficient information for, and whether each item measures identical trait levels in, the two nations. Confirmatory factor analysis on response 1,696 Korean and 3,669 American adults, gave to the measure revealed lack of fit and absence of factorial invariance across the two nations. Item response theory revealed significant variance for items on each factor across two countries that most items yielded limited psychometric information. And that each item measure different trait levels, suggesting that in its present form, the measure might lead to misleading results for, and across the two nations.