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Size effect on strength of Fiber-Reinforced Self-Compacting Concrete (SCC) after exposure to high temperatures

  • Gulsan, M. Eren;Abdulhaleem, Khamees N.;Kurtoglu, Ahmet E.;Cevik, Abdulkadir
    • Computers and Concrete
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    • v.21 no.6
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    • pp.681-695
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    • 2018
  • This pioneer study investigates the size effect on the compressive and tensile strengths of fiber-reinforced self-compacting concrete (FR-SCC) with different specimens, before and after exposure to elevated temperatures. 432 self-compacting concrete (SCC) specimens with two concrete grades (50 and 80MPa) and three steel fiber ratios (0%, 0.5% and 1%) were prepared and tested. Moreover, based on the experimental results, new formulations were proposed to predict the residual strengths for different specimens. A parametric study was also carried out to investigate the accuracy of proposed formulations. Residual strength results showed that the cylinder specimen with dimensions of $100{\times}200mm$ was the most affected, while the cube with a size of 100 mm maintained a constant difference with the standard cylinder ($150{\times}300mm$). Temperature effect on the cube specimen (150 mm) was the least in comparison to other specimen sizes and types. In general, provision of steel fibers in SCC mixtures resulted in a reduction in temperature effect on the variance of a conversion factor. Parametric study results confirm that the proposed numerical models are safe to be used for all types of SCC specimens.

Experimental study on concrete-encased composite columns with separate steel sections

  • Xiao, Congzhen;Deng, Fei;Chen, Tao;Zhao, Zuozhou
    • Steel and Composite Structures
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    • v.23 no.4
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    • pp.483-491
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    • 2017
  • This paper presents an experimental study on the behavior of concrete-encased composite columns with multiseparate steel sections subjected to axial and eccentric loads. Six 1/4-scaled concrete-encased composite columns were tested under static loads. The specimens were identical in geometric dimensions and configurations, and the parameter of this experiment was the eccentricity ratio of the applied load. Each two of the specimens were loaded with 0, 10%, and 15% eccentricity ratios. The capacity, deformation pattern, and failure mode of the specimens were carefully examined. Test results indicate that full composite action between the concrete and the steel sections can be realized even though the steel sections do not connect with one another. The concrete-encased composite columns can develop stable behavior and sufficient deformation capacity by providing enough transverse reinforcing bars. Capacities of the specimens were evaluated based on both the Plain Section Assumption (PSA) method and the superimposition method. Results show that U.S. and Chinese codes can be accurate and safe in terms of bending capacities. Test results also indicate that the ACI 318 and Mirza methods give the best predictions on the flexural stiffness of this kind of composite columns.

Observations of surface roughness of Co-Cr alloys according to grinding time of dental barrel finishing (치과용 바렐연마기의 연마시간에 따른 Co-Cr 합금의 표면거칠기 관찰)

  • Ko, Hyeon-Jeong;Park, Yu-Jin;Choi, Sung-Min
    • Journal of Technologic Dentistry
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    • v.43 no.3
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    • pp.93-98
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    • 2021
  • Purpose: The aim of this study was to observe the surface roughness and surface topography of cobalt-chrome (Co-Cr) alloys with grinding time in dental barrel finishing. Methods: This study involved two types of Co-Cr alloys. Specimens were manufactured with the dimensions 10×10×2 mm. Each specimen was cast according to the manufacturer's instructions. The cast alloys were polished for 35 minutes at intervals of five minutes in an automatic barrel finishing. Specimens were imaged with a three-dimensional optical microscope to measure surface roughness. Results: BC specimens and GM specimens had the highest roughness (Ra) values in the ungrained control group, and the lowest Ra values were measured 20 minutes after grinding. Conclusion: The best conditions for grinding Co-Cr alloy using a dental barrel finishing were a weight ratio of polishing media, water, and compound of 150 g:200 g:5 g, and a rotation speed of 450 rpm. Grinding time to obtain appropriate surface roughness should be limited to 15 to 30 minutes.

A Case Report on a Patient Treated with Combined Korean Medicine for Chronic Headache with Digestive Symptoms (소화기 증상을 동반한 만성두통 환자에 대한 한방복합치료 치험 1례)

  • Choi, Gyu-cheol;Bae, Ji-eun;Park, Jae-won;Kim, Dong-jin;Hong, Jeong-su
    • The Journal of Internal Korean Medicine
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    • v.42 no.5
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    • pp.923-930
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    • 2021
  • Objectives: The purpose of this study was to examine the effect of combined Korean medical treatment on chronic headache with digestive symptoms. Methods: We collected data from October to December 2020 and evaluated the efficacy of combined Korean medical treatment using the Korean Headache Impact Test-g (KHIT-6), European Quality of Life Five Dimensions (EQ5D) Scale, and Numerical Rating Scale (NRS) at admission, after two weeks of hospitalization, and on discharge. Results: At the end of treatment, the patient had increased EQ5D and reduced KHIT-6 and NRS scores. Conclusions: After the combined Korean medical treatment, the patient showed improvement, suggesting the efficacy of treatment.

Behavior of reinforced sustainable concrete hollow-core slabs

  • Al-Azzawi, Adel A.;Shallal, Mustafa S.
    • Advances in concrete construction
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    • v.11 no.4
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    • pp.271-284
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    • 2021
  • This study aims to trace the response of twelve one-way sustainable concrete hollow-core slabs made by reducing cement content and using replacement of coarse aggregate by plastic aggregate. The trial mixes comprise the 25, 50, 75, and 100% replacement of natural coarse aggregate. The compressive strength of the resulting lightweight concrete with full replacement of coarse aggregate by plastic aggregate was 28 MPa. These slabs are considered to have a reduced dead weight due to using lightweight aggregate and due to reducing cross-section through using voids. The samples are tested under two verticals line loads. Several parameters are varied in this study such as; nature of coarse aggregate (natural or recycled), slab line load location, the shape of the core, core diameter, flexural reinforcement ratio, and thickness of the slab. Strain gauges are used in the present study to measure the strain of steel in each slab. The test samples were fourteen one-way reinforced concrete slabs. The slab's dimensions are (1000 mm), (600 mm), (200 mm), (length, width, and thickness). The change in the shape of the core from circular to square and the use of (100 mm) side length led to reducing the weight by about (46%). The cracking and ultimate strength is reduced by about (5%-6%) respectively. With similar values of deflection. The mode of failure will remain flexural. It is recognized that when the thickness of the slab changed from (200 mm to 175 mm) the result shows a reduction in cracking and ultimate strength by about (6% and 7%) respectively.

Remote Distance Measurement from a Single Image by Automatic Detection and Perspective Correction

  • Layek, Md Abu;Chung, TaeChoong;Huh, Eui-Nam
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.8
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    • pp.3981-4004
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    • 2019
  • This paper proposes a novel method for locating objects in real space from a single remote image and measuring actual distances between them by automatic detection and perspective transformation. The dimensions of the real space are known in advance. First, the corner points of the interested region are detected from an image using deep learning. Then, based on the corner points, the region of interest (ROI) is extracted and made proportional to real space by applying warp-perspective transformation. Finally, the objects are detected and mapped to the real-world location. Removing distortion from the image using camera calibration improves the accuracy in most of the cases. The deep learning framework Darknet is used for detection, and necessary modifications are made to integrate perspective transformation, camera calibration, un-distortion, etc. Experiments are performed with two types of cameras, one with barrel and the other with pincushion distortions. The results show that the difference between calculated distances and measured on real space with measurement tapes are very small; approximately 1 cm on an average. Furthermore, automatic corner detection allows the system to be used with any type of camera that has a fixed pose or in motion; using more points significantly enhances the accuracy of real-world mapping even without camera calibration. Perspective transformation also increases the object detection efficiency by making unified sizes of all objects.

A Study on the Reliability Evaluation Index Development for the Information Resources Retained by Institutions: Focusing on Humanities Assets

  • Jeong, Dae-Keun;Noh, Younghee
    • International Journal of Knowledge Content Development & Technology
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    • v.9 no.2
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    • pp.65-89
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    • 2019
  • This study has the aim of developing an evaluation index that can help evaluate the reliability of the information resources of institutions retaining humanities assets for the purposes of laying out the foundation for providing one-stop portal service for humanities assets. To this end, the evaluation index was derived through the analysis of previous research, case studies, and interviews with experts, the derived evaluation index was then applied to the humanities assets retaining institutions to verify the utility. The institutional information resources' reliability evaluation index consisted of the two dimensions of the institutions' own reliability evaluation index. The institution provided a service and system evaluation index. The institutions' own reliability evaluation index consisted of 25 points for institutional authority, 25 points for data collection and construction, 30 points for data provision, and 20 points for appropriateness of data, for a total of 100 points, respectively. The institution provided service and system evaluation indexes consisting of 25 points for information quality, 15 points for appropriateness (decency), 15 points for accessibility, 20 points for tangibility, 15 points for form, and 10 points for cooperation, for the total of 100 points, respectively. The derived evaluation index was used to evaluate the utility of 6 institutions representing humanities assets through application. Consequently, the reliability of the information resources retained by the Research Information Service System (RISS) of the Korea Education & Research Information Service (KERIS) turned out to be the highest.

Finite element analysis of long-term changes of the breast after augmentation mammoplasty: Implications for implant design

  • Myung, Yujin;Lee, Jong-Gu;Cho, Maenghyo;Heo, Chan Yeong
    • Archives of Plastic Surgery
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    • v.46 no.4
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    • pp.386-389
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    • 2019
  • The development of breast implant technology continues to evolve over time, but changes in breast shape after implantation have not been fully elucidated. Thus, we performed computerized finite element analysis in order to better understand the trajectory of changes and stress variation after breast implantation. The finite element analysis of changes in breast shape involved two components: a static analysis of the position where the implant is inserted, and a dynamic analysis of the downward pressure applied in the direction of gravity during physical activity. Through this finite element analysis, in terms of extrinsic changes, it was found that the dimensions of the breast implant and the position of the top-point did not directly correspond to the trajectory of changes in the breast after implantation. In addition, in terms of internal changes, static and dynamic analysis showed that implants with a lower top-point led to an increased amount of stress applied to the lower thorax. The maximum stress values were 1.6 to 2 times larger in the dynamic analysis than in the static analysis. This finding has important implications for plastic surgeons who are concerned with long-term changes or side effects, such as bottoming-out, after anatomic implant placement.

Soft Tissue Measurement Method Using Radiopaque Material on Cone-beam Computed Tomography: An Ex Vivo Validation Study

  • Lee, Hae-Seok;Yun, Jeong-Ho;Lee, Dong-Won
    • Implantology
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    • v.22 no.4
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    • pp.210-218
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    • 2018
  • Purpose: The purpose of this study was to investigate the validity and reproducibility of a method based on cone-beam computed tomography (CBCT) technology for the visualization and measurement of gingival soft-tissue dimensions. Material and Methods: A total of 66 selected points in soft-tissue of the ex vivo head of an adult pig were investigated in this study. For the measurement of radiographic thickness (RT), wet soft-tissue surfaces were lightly covered with barium sulfate powder using a powder spray. CBCT was taken and DICOM files were assessed for soft-tissue thickness measurement at reference points. A periodontal probe and a rubber stop were used for the measurement of trans-gingival probing thickness (TPT). After flap elevation, actual thickness of soft-tissue (actual thickness, AT) was measured. Correlation analysis and intraclass correlation coefficients analysis (ICC) were performed for AT, TPT, and RT. Results: All variables were distributed normally. Strong significant correlations of AT with RT and TPT values were found. The two ICC values between TPT vs. AT and RT vs. AT differed significantly. Conclusion: Our results indicated that correlation of RT was stronger than that of TPT with AT. We concluded that soft tissue measurement with CBCT could be a reliable method, compared to the trans-gingival probing measurement method.

Ali Bey Hüseyinzade and His Impact on National Thought in Turkey and the Caucasus

  • UZER, UMUT
    • Acta Via Serica
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    • v.3 no.2
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    • pp.135-150
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    • 2018
  • Ali Bey $H{\ddot{u}}seyinzade$ (1864-1940) was one of the most significant Azerbaijani Turkish intellectuals in the late nineteenth and early twentieth centuries, formulating Azerbaijani national identity around its Turkish, Islamic and territorial dimensions. His solution to the ambiguities of the identity crisis among the Turkic-Muslim people of Azerbaijan was Turkification, Islamization and Europeanization for the Turkic and Muslim peoples of the Caucasus and Ottoman Turkey. Ali Bey $H{\ddot{u}}seyinzade$ was an influential Azerbaijani Turkish intellectual who had a direct impact on Turkish nationalists in the late Ottoman Empire and early Republican Turkey. $H{\ddot{u}}seyinzade^{\prime}s$ formulation of the triple processes of Turkification, Islamization and Europeanization spread among the Azerbaijani and Ottoman Turkish intellectuals in their respective countries. This article aims to discuss the ideas of Ali Bey $H{\ddot{u}}seyinzade$, especially regarding nationality, religion and Westernism and their impact on intellectuals and policy makers in the Caucasus and Turkey. His physical odyssey from Tsarist Russia into the Ottoman Empire is indicative of his ideological proclivities and his subsequent influence on the Turkish-speaking peoples in the two major empires in the late nineteenth and early twentieth centuries.