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Elastic flexural and torsional buckling behavior of pre-twisted bar under axial load
Chang Hong Chen,Yao Yao,Ying Huang 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.2
According to deformation features of pre-twisted bar, its elastic bending and torsion buckling equation is developed in the paper. The equation indicates that the bending buckling deformations in two main bending directions are coupled with each other, bending and twist buckling deformations are coupled with each other as well. However, for pre-twisted bar with dual-axis symmetry cross-section, bending buckling deformations are independent to the twist buckling deformation. The research indicates that the elastic torsion buckling load is not related to the pre-twisted angle, and equals to the torsion buckling load of the straight bar. Finite element analysis to pre-twisted bar with different pre-twisted angle is performed , the prediction shows that the assumption of a plane elastic bending buckling deformation curve proposed in previous literature (Shadnam and Abbasnia 2002) may not be accurate, and the curve deviates more from a plane with increasing of the pre-twisting angle. Finally, the parameters analysis is carried out to obtain the relationships between elastic bending buckling critical capacity, the effect of different pre-twisted angles and bending rigidity ratios are studied. The numerical results show that the existence of the pre-twisted angle leads to “resistance” effect of the stronger axis on buckling deformation, and enhances the elastic bending buckling critical capacity. It is noted that the “resistance” is getting stronger and the elastic buckling capacity is higher as the cross section bending rigidity ratio increases.
Yao-Chun Yang,Min-Hong Hsieh,Jui-Teng Chien,Keng-Chang Liu,Chang-Chen Yang 대한골다공증학회 2023 Osteoporosis and Sarcopenia Vol.9 No.1
Objectives: Sacral insufficiency fracture (SIF) is not an uncommon osteoporosis fracture among the elderly. Aside from traditional treatments, sacroplasty and teriparatide (TPTD) injection have been introduced. This report aims to compare the effects of sacroplasty and teriparatide on clinical outcomes of SIF. Methods: Thirty-one elderly patients with SIF were enrolled in this retrospective observational study. Four male patients were excluded. Fourteen patients who received TPTD for 6 months were classified into the TPTD group (TT), and 13 who underwent sacroplasty were classified into the sacroplasty group (SS). All patients in both groups were instructed to take calcium and vitamin D supplements daily. Their symptoms and signs, visual analog score (VAS), Oswestry disability index (ODI), and radiographic studies were retrospectively reviewed. Results: The TT group showed significantly lower VAS than SS group after 3 (P < 0.001) and 6 months of treatment (P < 0.001). The TT group also has significant lower ODI than SS group after 1 (P = 0.010), 3 (P = 0.005) and 6 months (P < 0.001) of treatment. Upon generalized estimating equations (GEE) analysis, the TT group showed significantly more reduction in both VAS and ODI compared to the SS group at 1 month (P = 0.022, P = 0.001), 3 months (P < 0.001, P < 0.001), and 6 months (P < 0.001, P < 0.001) post-treatment. Conclusions: Postmenoposal woman with SIF who received TPTD healed better than those who underwent sacroplasty after 1 month treatment.
Crop Production Estimation and Famine Evaluation for North Korea by Using Remote Sensing Technology
Yao, Wang Chang,Zhen, Yang,Zheng, Niu 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1
Crop production assessments are extremely valuable because of their economic importance in influencing international trade and national economic policies. Associated with the serious problems of food supplies in the whale wand, crop production assessments are becoming outstandingly significant. Moreover, because of its goad time properties and accuracy, remote sensing technique has become an important measure of crap production assessments. In addition, models for forecasting native crop yields using remotely sensed satellite data have been intensively studied and well developed.
The Quantitative Evaluation of Automatic Segmentation in Lumbar Magnetic Resonance Images
Yao-Wen Liang,Yu-Ting Fang,Ting-Chun Lin,Cheng-Ru Yang,Chih-Chang Chang,Hsuan-Kan Chang,Chin-Chu Ko,Tsung-Hsi Tu,Li-Yu Fay,Jau-Ching Wu,Wen-Cheng Huang,Hsiang-Wei Hu,You-Yin Chen,Chao-Hung Kuo 대한척추신경외과학회 2024 Neurospine Vol.21 No.2
Objective: This study aims to overcome challenges in lumbar spine imaging, particularly lumbar spinal stenosis, by developing an automated segmentation model using advanced techniques. Traditional manual measurement and lesion detection methods are limited by subjectivity and inefficiency. The objective is to create an accurate and automated segmentation model that identifies anatomical structures in lumbar spine magnetic resonance imaging scans. Methods: Leveraging a dataset of 539 lumbar spinal stenosis patients, the study utilizes the residual U-Net for semantic segmentation in sagittal and axial lumbar spine magnetic resonance images. The model, trained to recognize specific tissue categories, employs a geometry algorithm for anatomical structure quantification. Validation metrics, like Intersection over Union (IOU) and Dice coefficients, validate the residual U-Net’s segmentation accuracy. A novel rotation matrix approach is introduced for detecting bulging discs, assessing dural sac compression, and measuring yellow ligament thickness. Results: The residual U-Net achieves high precision in segmenting lumbar spine structures, with mean IOU values ranging from 0.82 to 0.93 across various tissue categories and views. The automated quantification system provides measurements for intervertebral disc dimensions, dural sac diameter, yellow ligament thickness, and disc hydration. Consistency between training and testing datasets assures the robustness of automated measurements. Conclusion: Automated lumbar spine segmentation with residual U-Net and deep learning exhibits high precision in identifying anatomical structures, facilitating efficient quantification in lumbar spinal stenosis cases. The introduction of a rotation matrix enhances lesion detection, promising improved diagnostic accuracy, and supporting treatment decisions for lumbar spinal stenosis patients.
Evaluating the effects of programs for reducing achievement gaps: a case study in Taiwan
Yao-Ting Sung,Fen-Lan Tseng,Nien-Ping Kuo,Tien-Ying Chang,Jia-Min Chiou 서울대학교 교육연구소 2014 Asia Pacific Education Review Vol.15 No.1
Considering that achievement gaps have become a serious educational problem worldwide, the Ministry of Education in Taiwan has been addressing a series of policies to reduce achievement gaps, but the effect of these policies has not yet been carefully examined. Therefore, the present study investigated current educational policies, achievement gap phenomenon, and its changing trends in the use of national standardized tests in Taiwan and evaluated the degree to which these policies are reducing the achievement gaps among Taiwanese students. Junior high school graduates who took the high school entrance examination between 2004 and 2010 were recruited to examine the associations between their academic achievements and variables such as socioeconomic status (SES), ethnicity, and school district. Time series analyses were conducted to determine the longitudinal trends for the achievement gaps. The results revealed that achievement gaps are decreasing among different ethnicities, but they are increasing among different SESs and school districts. These findings demonstrate some positive effects of the educational policies introduced in Taiwan, but also the need for further modification and precise implementation of these policies. Suggestions for implementing educational programs and policies to reduce achievement gaps are also presented.
A Busbar Integrated SiC-based Converter with Embedded Heat-pipes
Yao Chang,Amir Sajjad Bahman,Haoze Luo,Wuhua Li,Xiangning He,Francesco Iannuzzo,Frede Blaabjerg 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In this paper, a bus-bar integrated packaging technology for press-pack power modules is proposed. The proposed packaging technology features high power-density, even pressure distribution among chips, and low stray parameters. The structure design and fabrication flow process are analyzed and experiments are made to verify the feasibility of proposed solution. The critical challenge about the package is related to thermal management. To reduce the thermal stress of chips, a heat-pipe integrated heatsink is developed and finite-element-method (FEM) simulations are used to evaluate the cooling performance of the proposed heatsink. The results demonstrate that the proposed heatsink has a relatively low cost and works effectively. It paves the way to better packaging design and more efficient thermal management method for high power devices.
Progressive collapse analysis of steel frame structure based on the energy principle
Chang Hong Chen,Yan Fei Zhu,Yao Yao,Ying Huang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.3
The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.