• Structural Engineering and Mechanics
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• 제73권5호
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• pp.529-542
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• 2020

As limited well-documented experimental data are available for assessing the attributes of different deformation components of flanged walls, few appropriate models have been established for predicting the inelastic responses of flanged walls, especially those of asymmetrical flanged walls. This study presents the experimental results for three large-scale T-shaped reinforced concrete walls and examines the variations in the flexural, shear, and sliding components of deformation with the total deformation over the entire loading process. Based on the observed deformation behavior, a simple model based on moment-curvature analysis is established to estimate flexural deformations, in which the changes in plastic hinge length are considered and the deformations due to strain penetration are modeled individually. Based on the similar gross shapes of the curvature and shear strain distributions over the wall height, a proportional relationship is established between shear displacement and flexural rotation. By integrating the deformations due to flexure, shear, and strain penetration, a new load-deformation analytical model is proposed for flexure-dominant flanged walls. The proposed model provides engineers with a simple, accurate modeling tool appropriate for routine design work that can be applied to flexural walls with arbitrary sections and is capable of determining displacements at any position over the wall height. By further simplifying the analytical model, a simple procedure for estimating the ultimate displacement capacity of flanged walls is proposed, which will be valuable for performance-based seismic designs and seismic capacity evaluations.

• Wind and Structures
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• 제23권3호
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• pp.231-251
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• 2016

This paper presents the experimental results of the wind tunnel tests for three symmetric, rectangular, tall building models on a typical open terrain considering the torsional motion-induced vibrations. The time histories of the wind pressure on these models under different reduced wind speeds and torsional amplitudes are obtained through the multiple point synchronous scanning pressure technique. Thereafter, the characteristics of both the Root Mean Square (RMS) coefficients and the spectra of the base shear/torque in the along-wind, across-wind, and torsional directions, respectively, are discussed. The results show that the RMS coefficients of the base shear/torque vary in the three directions with both the reduced wind speeds and the torsional vibration amplitudes. The variation of the RMS coefficients in the along-wind direction results mainly from the change of the aerodynamic forces, but sometimes from aeroelastic effects induced by torsional vibration. However, the variations of the RMS coefficients in the across-wind and torsional directions are caused by more equal weights of both the aerodynamic forces and the aeroelastic effects. As such, for the typical tall buildings, the modification of the aerodynamic forces in the along-wind, across-wind, and torsional directions, respectively, and the aeroelastic effects in the across-wind and torsional directions should be considered. It is identified that the torsional vibration amplitudes and the reduced wind speeds are two significant parameters for the aerodynamic forces on the structures in the three directions.

• Macromolecular Research
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• 제17권11호
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• pp.850-855
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• 2009

Keratin is an important protein used in wound healing and tissue recovery. In this study, keratin was modified chemically with iodoacetic acid (IAA) to enhance its solubility in organic solvent. Poly(hydroxybutylate-co-hydroxyvalerate) (PHBV) and modified keratin were dissolved in hexafluoroisopropanol (HFIP) and electrospun to produce nanofibrous mats. The resulting mats were surface-characterized by ATR-FTIR, field-emission scanning electron microscopy (FE-SEM) and electron spectroscopy for chemical analysis (ESCA). The pure m-keratin mat was cross-linked with glutaraldehyde vapor to make it insoluble in water. The biodegradation test in vitro showed that the mats could be biodegraded by PHB depolymerase and trypsin aqueous solution. The results of the cell adhesion experiment showed that the NIH 3T3 cells adhered more to the PHBV/m-keratin nanofibrous mats than the PHBV film. The BrdU assay showed that the keratin and PHBV/m-keratin nanofibrous mats could accelerate the proliferation of fibroblast cells compared to the PHBV nanofibrous mats.

• 대한치과교정학회지
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• 제52권3호
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• pp.165-171
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• 2022

Objective: This cross-sectional study aimed to investigate the characteristics of malocclusions in scoliotic patients through clinical examinations. Methods: Fifty-eight patients with idiopathic scoliosis (IS) and 48 patients with congenital scoliosis (CS) participated in the study. A randomly selected group of 152 orthopedically healthy children served as the control group. Standardized orthodontic and orthopedic examination protocols were used to record the occlusal patterns and type of scoliosis. Assessments were made by three experienced orthodontists and a spinal surgery team. The differences in the frequency distribution of occlusal patterns were evaluated by the chi-squared test. Results: In comparison with patients showing IS, patients with CS showed a higher incidence of Cobb angle ≥ 45° (p = 0.020) and included a higher proportion of patients receiving surgical treatments (p < 0.001). The distribution of the Angle Class II subgroup was significantly higher in the IS (p < 0.001) and CS (p = 0.031) groups than in the control group. In comparison with the healthy controls, the CS and IS groups showed significantly higher (p < 0.05) frequencies of asymmetric molar and asymmetric canine relationships, upper and lower middle line deviations, anterior deep overbite, unilateral posterior crossbite, and canted occlusal plane, with the frequencies being especially higher in CS patients and to a lesser extent in IS patients. Conclusions: Patients with scoliosis showed a high frequency of malocclusions, which were most obvious in patients with CS.

• Earthquakes and Structures
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• 제20권4호
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• pp.365-375
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• 2021

Rammed earth (RE) buildings have existed all over the world for thousands of years, and have gained increasing attention because of its sustainable advantages, however, the shrinkage cracks reduce its bearing capacity and seriously affect its durability and applicability. In this study, the shrinkage cracks test was carried out to investigate the effects of initial water content, proportion of sand and gravel, compaction degree, thickness and the additives (polypropylene fiber, cement and sodium silicate) of shrinkage cracks in RE buildings, ten groups of RE samples were prepared and dried outdoors to crack. Four quantitative parameters of geometrical structure of crack patterns were used to evaluate the development of cracks. The results show that the specimens cracking behavior and the geometrical structure of crack patterns are significantly influenced by these considered factors. The formation of crack can be accelerated with the increase of initial water content and thickness of specimen, while restricted with the increase of the compaction degree and the proportion of sand and gravel. Moreover, the addition of 1% polypropylene fiber, 10% cement and 0.5 volume ratio sodium silicate can significantly restrain the form and development of cracks. In RE construction, these factors should be considered comprehensively to prevent the harm caused by shrinkage cracks. Further works should be carried out to obtain the optimum dosage of the additives, which can benefit the construction of RE buildings in future.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.1-16
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• 2022

This work elaborately investigates the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the suspended monorail vehicle-guideway system (SMVGS). Firstly, a spatial dynamic analysis model of the SMVGS is established by adopting ANSYS parameter design language. Then, the dynamic interaction between a vehicle with maximum design load and guideway is investigated by numerical simulation and field tests, revealing the vehicle-guideway dynamic features. Subsequently, the influences of the guideway geometry parameters and track irregularity on the dynamic performances of the SMVGS are analyzed and discussed in detail, and the reasonable ranges of several key geometry parameters of the guideway are also obtained. Results show that the vehicle-guideway dynamic responses change nonlinearly with an increase of the guideway span, and especially the guideway dynamic performances can be effectively improved by reducing the guideway span; based on a comprehensive consideration of all performance indices of the SMVGS, the deflection-span ratio of the suspended monorail guideway is finally recommended to be 1/1054~1/868. The train load could cause a large bending deformation of the pier, which would intensify the car-body lateral displacement and decrease the vehicle riding comfort; to well limit the bending deformation of the pier, its cross-section dimension is suggested to be more than 0.8 m×0.8 m. The addition of the track irregularity amplitude has small influences on the displacements and stress of the guideway; however, it would significantly increase the vehicle-guideway vibrations and rate of load reduction of the driving tyre.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권12호
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• pp.3976-3990
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• 2022

Currently, cross-attention is widely used in Siamese trackers to replace traditional correlation operations for feature fusion between template and search region. The former can establish a similar relationship between the target and the search region better than the latter for robust visual object tracking. But existing trackers using cross-attention only focus on rich semantic information of high-level features, while ignoring the appearance information contained in low-level features, which makes trackers vulnerable to interference from similar objects. In this paper, we propose a Multi-level Cross-attention Siamese network(MCSiam) to aggregate the semantic information and appearance information at the same time. Specifically, a multi-level cross-attention module is designed to fuse the multi-layer features extracted from the backbone, which integrate different levels of the template and search region features, so that the rich appearance information and semantic information can be used to carry out the tracking task simultaneously. In addition, before cross-attention, a target-aware module is introduced to enhance the target feature and alleviate interference, which makes the multi-level cross-attention module more efficient to fuse the information of the target and the search region. We test the MCSiam on four tracking benchmarks and the result show that the proposed tracker achieves comparable performance to the state-of-the-art trackers.

• 한국과학교육학회지
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• 제18권3호
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• pp.303-312
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• 1998

본 연구는 화학 평형 단원에 대한 멀티미디어 CAl를 제작하고, 고등학교 화학수업에 적용하여 성취도와 태도 면에서 전통적 수업과의 효과를 비교하였다. 이를 위하여 수업처치 전에 화학수업과 컴퓨터에 대한 태도 검사를 하였고, 중간고사 성적을 공변인으로, 중간고사의 과학성적을 구획변인으로 사용하였다. 화학 평형 단원을 대상으로 각각 전통적인 수업과 CAl를 수행한 후에 성취도 검사와 태도 검사를 실시하였다. 컴퓨터를 이용하여 화학수업을 받은 학생은 전통적인 수업을 받은 학생에 비하여 성취도는 유의미하게 향상 되었으나, 태도의 향상은 유의미하지 않았다. 또한 학습자의 사전 성취수준과 수업처치와의 상호작용은 관찰되지 않았다. 성별로 분석해 보니 여학생은 CAl에 의해 성취도가 향상되었으나, 남학생은 차이를 보이지 않았다. 이해와 적용의 하위범주 중 적용문제 영역에서 CAl에 의한 성취도의 향상이 있었으며, 화학 평형의 법칙, 화학 평형의 개념, 평형 이동의 적용 세 부분으로 나누었을 때 화학 평형의 개념에서 성취도의 향상이 가장 컸다. CAl가 컴퓨터에 대한 태도와 화학수업에 대한 태도에 긍정적인 변화를 주지 않았으며, 남학생은 CAl에 의해 화학수업에 대한 태도와 컴퓨터에 대한 태도 모두 긍정적으로 변했으나 여학생은 그렇지 못하였다. 이상의 결과에 대한 교육적 의미를 논의하였다.

• Steel and Composite Structures
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• 제29권2호
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• pp.273-286
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• 2018

In recent years, significant progress has been made in developing design rules for stainless steel members, while the investigation on bolted connections is relatively limited, in particular at elevated temperatures. In this paper, experimental and numerical investigations on stainless steel bolted connections at ambient and elevated temperatures from the literature were reviewed. Firstly, the research program that focused on structural behavior of cold-formed stainless steel (CFSS) bolted connections at elevated temperatures carried out by the authors were summarized. Over 400 CFSS single shear and double shear bolted connection specimens were tested. The tests were conducted in the temperature ranged from 22 to $950^{\circ}C$ using both steady state and transient state test methods. It is shown that the connection strengths decrease as the temperature increases in the similar manner for the steady state test results and the transient state test results. Generally, the deterioration of the connection strengths showed a similar tendency of reduction to those of the material properties for the same type of stainless steel regardless of different connection types and different configurations. It is also found that the austenitic stainless steel EN 1.4571 generally has better resistance than the stainless steel EN 1.4301 and EN 1.4162 for bolted connections at elevated temperatures. Secondly, extensive parametric studies that included 450 specimens were performed using the verified finite element models. Based on both the experimental and numerical results, bearing factors are proposed for bearing resistances of CFSS single shear and double shear bolted connections that subjected to bearing failure in the temperature ranged from 22 to $950^{\circ}C$. The bearing resistances of bolted connections obtained from the tests and numerical analyses were compared with the nominal strengths calculated from the current international stainless steel specifications, and also compared with the predicted strengths calculated using the proposed design equations. It is shown that the proposed design equations are generally more accurate and reliable than the current design rules in predicting the bearing resistances of CFSS (EN 1.4301, EN 1.4571 and EN 1.4162) bolted connections at elevated temperatures. Lastly, the proposed design rules were further assessed by the available 58 results of stainless steel bolted connections subjected to bearing failure in the literature. It is found that the proposed design rules are also applicable to the bearing resistance design of other stainless steel grades, including austenitic stainless steel (EN 1.4306), ferritic stainless steel (EN 1.4016) and duplex stainless steel (EN 1.4462).

• Asian Pacific Journal of Cancer Prevention
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• 제15권3호
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• pp.1233-1239
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• 2014

Background: The incidence of brain metastases (BM) varies in patients with non-small cell lung cancer (NSCLC), calls into question the value of prophylactic cranial irradiation (PCI). It is possible that clinicopathologic characteristics are associated with the development of BM, but these have yet to be identified in detail. Thus, we conducted the present meta-analysis on risk factors for BM and the value of PCI in patients with NSCLC. Methods: Eligible data were extracted and the risk factors for BM and the value of PCI in patients with NSCLC were analyzed by calculating the pooled odds ratio (OR). Heterogeneity was detected using Q and I-squared statistics, and publication bias was tested by funnel plots and Egger's test. Results: Six randomized controlled trials with a focus on the value of PCI and 13 eligible studies with a focus on risk factors for BM were included. PCI significantly reduced the incidence of BM in patients with NSCLC (p=0.000, pooled OR=0.34, 95% confidence interval = 0.37-0.59). Compared with non-squamous cell carcinoma, squamous cell carcinoma was associated with a low incidence of BM in patients with NSCLC (p=0.000, pooled OR=0.47, 95% confidence interval =0.34-0.65). The funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis. Conclusions: This meta-analysis provides statistical evidence that compared with non-squamous cell carcinoma, squamous cell carcinoma can be used as a predictor for BM in patients with NSCLC, and PCI might reduce the incidence of BM in patients with NSCLC, but does not provide a survival benefit.