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Influence of porosity and cement grade on concrete mechanical properties

  • Huang, Jiandong;Alyousef, Rayed;Suhatril, Meldi;Baharom, Shahrizan;Alabduljabbar, Hisham;Alaskar, Abdulaziz;Assilzadeh, Hamid
    • Advances in concrete construction
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    • v.10 no.5
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    • pp.393-402
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    • 2020
  • The given research focuses on examining the effect of relatively humidity (RH) and curing temperature on the hydrates as well as the porosity of calcium sulfoaluminate (CSA) cement pastes. Numerous tests, which consist of mercury intrusion porosimetry (MIP), thermosgravi metric (TG) and X-ray diffraction (XRD) were conducted. Various characterization techniques which include, scanning electron microscopy, Fourier transform microscopy along with X-ray diffraction evaluations were conducted on the samples to examine phase formation and crystallinity, morphology and microstructure along with bond formations and functional groups, respectively. During long-term study, the performance of concrete which consisted of limestone and flash-calcined was close to those from standard Portland cement concrete. Traditional classifications and methods of corrosion were widely used for the assessment of steel in concrete which may get employed to concrete which contains LC3 to recalibrate the range of polarization resistance for passitivity condition. For example, there is up to 79.5% and 146% respective flexural and compressive strengths. Moreover, they developed more advance electrical and thermo-mechanical performance with a substantial reduction in absorption of water of close to 400%. These advantages allow this research crucial to evaluate how these methods can be applied. Additionally, the research evaluates developed and more advanced cement preservation and repair techniques. The conclusion suggests concerted efforts by various stakeholders such as policy makers to enable low-carbon rates.

Effect of glass powder on the behaviour of high performance concrete at elevated temperatures

  • Kadik, Abdenour;Cherrak, Messaouda;Bali, Abderrahim;Boutchicha, Djilali;Hannawi, Kinda
    • Advances in concrete construction
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    • v.10 no.5
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    • pp.443-454
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    • 2020
  • In recent years, many studies have been done on the performance of concrete containing glass powder (GP). For the purpose of widespread use of GP in concrete mixes, a knowledge of the performance of such a mixture after a fire is essential for the perspective of structural use. This research work was carried out to evaluate the performance of High Performance Concrete (HPC) made with GP after being exposed to elevated temperature. The studied mixtures include partial replacement of cement by GP with up to 30%. The mechanical performance and structural alterations were assessed after high temperature treatment from 200℃ to 800℃. The mechanical performance was evaluated by testing the specimens to the compressive and tensile strength. In addition, the mass loss and the porosity were measured to notice the structural alterations. Changes in microstructure due to temperature was also investigated by the X-ray diffraction (XRD) and thermal gravimetric analyses (TGA) as well as porosity adsorption tests. The results of the concrete strength tests showed a slight difference in compressive strength and the same tensile strength performance when replacing a part of the cement by GP. However, after high temperature exposition, concrete with GP showed better performance than the reference concrete for temperature below 600℃. But, after heating at 800℃, the strength of the concrete with GP drop slightly more than reference concrete. This is accompanied by an important increase in mass loss and water porosity. After the microstructure analysis, no important changes happened differently for concrete with GP at high temperature except a new calcium silica form appears after the 800℃ heating.

Effect of horizontal joints on structural behavior of sustainable self-compacting reinforced concrete beams

  • Ibrahim, Omar Mohamed Omar;Heniegal, Ashraf Mohamed;Ibrahim, Khamis Gamal;Agwa, Ibrahim Saad
    • Advances in concrete construction
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    • v.10 no.5
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    • pp.455-462
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    • 2020
  • This study investigated the effect of horizontal casting joints on the mechanical properties and structural behavior of sustainable self-compacting reinforced concrete beams (SCRCB). The experimental research consisted of two stages. The first stage used four types of concrete mixtures which were produced to indicate the effects of cement replaced with cement waste at 0%, 5%, 10%, and 15% by weight of cement content on fresh concrete properties of self-compacting concrete (SCC) such as, passing ability, filling ability, and segregation resistance. In addition, mechanical properties such as compressive, tensile, and flexural strength were also studied. The second stage selected the best mixture from the first stage and studied the effect of horizontal casting joints on the structural behavior of sustainable SCRCBs. The effect of horizontal casting joints on the mechanical properties and structural behavior were at the 25%, 50%, 75%, and 100% of sample height. Load deflection, failure mode, and theoretical analysis were studied. Results indicated that the incorporation of replacement with cement waste by 5% to 10% led to economic and environmental advantages, and the results were acceptable for fresh and mechanical properties. The results indicated that delaying the time for casting the second layer and increasing the cement waste in concrete mixtures had a great effect on the mechanical properties of SCC. The ultimate load capacity of horizontal casting joints reinforced concrete beams slightly decreased compared with the control beam. The maximum deflection of casting joint beams with 75% of samples height is similar with the control beam. The experimental results of reinforced concrete beams were substantially acceptable with the theoretical results. The failure modes obtained the best forced casting joint on the structural behavior at 50% height of casting in the beam.

Development of reference materials for mortar: Determination of the components and relation with mixing ratio

  • Lim, Dong Kyu;Choi, Myoung Sung
    • Advances in concrete construction
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    • v.10 no.5
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    • pp.381-391
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    • 2020
  • This study aimed to develop reference materials (RMs) for mortar that can simulate the initial flow characteristics with constant quality over a long period. Through the previous research on the development of RMs for cement paste, the combination of limestone, glycerol, and water was used as the basic matrix for developing RMs for mortar in this study. In addition, glass beads of three particle sizes (0.5, 1.0, and 2.0 mm) and ISO standard sand were selected as tentative candidates to derive fine aggregate substitutes. The mixture of glass beads could simulate the initial flow characteristics of mortar, but under the same mixing ratio, replicates showed an unstable tendency to indicate inconsistent values due to the generation of electrostatic properties between materials and equipment. On the other hand, the mixture using ISO standard Sand not only simulates the constant flow characteristics for a long period of time, but also shows stable results with little error in replicates. Therefore, limestone, glycerol, ISO standard sand, and water were finally determined as components that met the required properties of RMs for mortar. The effect of each component on the flow characteristics of RMs was analyzed. It was found that glycerol increased the cohesion between the particles of standard sand, resulting in a constant increase both in the plastic viscosity and yield stress. Both limestone and standard sand had a dominant effect on the yield stress. The relationships between various mortar mixing ratios and the corresponding mixing ratios of RMs were established. In addition, the results of the verification experiment showed that the rheological properties of the RMs obtained through the relationships correlated with various water/cement ratios and the fine aggregate volume fractions of mortar obtained with same manner. In other words, the RMs for mortar developed in this study can be used as standard samples because they can simulate the initial flow characteristics of mortar of various mixing ratios for a long period without any chemical changes.

Multimedia Fingerprinting in DCT Block (DCT 블록의 멀티미디어 핑거프린팅)

  • Rhee, Kang-Hyeon
    • Journal of IKEEE
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    • v.15 no.3
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    • pp.241-247
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    • 2011
  • In this paper, it was implemented an algorithm of multimedia fingerprinting in DCT block. For the improvement of the limits of DRM’s ability, the proposed algorithm could be decided a responsibility boundary to judge a traitor who falsified the content according to perform separately a watermarking of content provider and a fingerprinting of content user. At the test image size($128{\times}128$) and block size($8{\times}8$) of the content provider, the measured PSNR is Inf~46.6dB with watermarking strength ${\Theta}=0.5{\sim}1.2$, and at a number of users and user's code length are n=7,15,31,63 and l=7,15,31,64 each, the measured PSNR is Inf~46.1 with fingerprinting code length l=7,15,31,63. Finally, a traitor tracing of the falsified content is approached to a trace ratio 1 which is extended to n-1.

Elicitors which Induce the Accumulation of p-Coumaroylamino Acids in Ephedra distachya Cultures

  • Song, Kyung-Sik;Sankawa, Ushio;Ebizuka, Yutaka
    • Archives of Pharmacal Research
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    • v.17 no.1
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    • pp.26-30
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    • 1994
  • Some ammonium oxalate soluble pectic fragments prepared from cultured cell wall of Ephycla distrahya elicited the accumulation of p-coumarocylamino acids (p-CAA) in E. distachya cultures while water soluble and alkali soluble fractions had no activity. Partial purification of the pectic fragments fraction using DEAE-cellulose chromatography afforded two active fractions (PS-I and PS-II) which were composed of mainly uronic acids (98-99 w/w %). They elicited the accumulation of p-CAA in an amount of 52-60 nmol per gram fresh weight of cultures. The acidic sugar compositions of PS-I and PS-II were found to be galacturonic acid and glucuronic acid by TLC analysis. They were supposed to act as endogenous elicitors of p-CAA accumulation. In order to investigate the effect of ethylene on p-CAA accumulation, Ethrel, which is known as ethylene generator, and ACC(1-aminocyclopropane-1-carboxylic acid), a direct precusor of ethylene biosynthesis, were added to the culture. However, they did not glycopeptide elicitor [(Con A-II)], either. Consequently, no relationships between ethylene and p-CAA accumulation were recognized. Several tentative elicitors were teted for their activity. Commercial yeast glucan, $CuCl_2$, laminarin and laminariheptaose had slight activity whereas ${\alpha}$-methylmannopyranoside and commercial yeast mannan had no elicitor activity. ${\alpha}$-methylmannopyranoside which has been known as a tentative inhibitor of glucan elicitor in Glycine max did not affect on the elicitor activity of Con A-II.

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A Study on Gait Imbalance Estimation System using 3-axis Accelerometer (3축 가속도 센서를 이용한 보행 불균형 평가 시스템에 관한 연구)

  • Choi, C.H.;Park, Y.D.;Sim, H.M.;Lee, S.M.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.9 no.1
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    • pp.37-43
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    • 2015
  • In this paper, an efficient system using 3-axis accelerometer is proposed to diagnose the gait imbalance. The proposed hardware system consists of two 3-axis accelerometers to measure 3 directional acceleration of ankles and an embedded system to transfer the data. The acquired data were normalized and then compared to analyze the symmetry between normal and abnormal gait with ROCC (ratio of correlation coefficient). 10 healthy subjects were participated and each subject repeated the experiment 5 times. To make unbalanced ambulation, the height of the heel of one foot was changed during experiments. From the results, it is verified that ROCC index grew apart from the reference according to growing imbalance and the proposed system could be available for estimation of gait imbalance.

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Rapid Identification of Ginseng Cultivars (Panax ginseng Meyer) Using Novel SNP-Based Probes

  • Jo, Ick-Hyun;Bang, Kyong-Hwan;Kim, Young-Chang;Lee, Jei-Wan;Seo, A-Yeon;Seong, Bong-Jae;Kim, Hyun-Ho;Kim, Dong-Hwi;Cha, Seon-Woo;Cho, Yong-Gu;Kim, Hong-Sig
    • Journal of Ginseng Research
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    • v.35 no.4
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    • pp.504-513
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    • 2011
  • In order to develop a novel system for the discrimination of five ginseng cultivars (Panax ginseng Meyer), single nucleotide polymorphism (SNP) genotyping assays with real-time polymerase chain reaction were conducted. Nucleotide substitution in gDNA library clones of P. ginseng cv. Yunpoong was targeted for the SNP genotyping assay. From these SNP sites, a set of modified SNP specific fluorescence probes (PGP74, PGP110, and PGP130) and novel primer sets have been developed to distinguish among five ginseng cultivars. The combination of the SNP type of the five cultivars, Chungpoong, Yunpoong, Gopoong, Kumpoong, and Sunpoong, was identified as 'ATA', 'GCC', 'GTA', 'GCA', and 'ACC', respectively. This study represents the first report of the identification of ginseng cultivars by fluorescence probes. An SNP genotyping assay using fluorescence probes could prove useful for the identification of ginseng cultivars and ginseng seed management systems and guarantee the purity of ginseng seed.

An enhanced root system developmental responses under drought by inoculation of rhizobacteria (Streptomyces mutabilis) contributed to the improvement of dry matter production in rice

  • Suralta, Roel R.;Cruz, Jayvee A.;Cabral, Maria Corazon J.;Niones, Jonathan M.;Yamauchi, Akira
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2017.06a
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    • pp.231-231
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    • 2017
  • Drought limits rice production under upland condition. This study quantified the effect of rhizobacteria inoculation on rice root system developmental response to drought and its role in maintaining high soil water use, and dry matter production under drought using NSIC Rc192 (rainfed lowland rice variety). The source of inoculant was Streptomyces mutabilis, a recently isolated rhizobacteria containing plant growth promoting compounds such as ACC deaminase, indole-3-acetic acid and phosphatase (Cruz et al., 2014, 2015). In the first experiment, pre-germination inoculation of seeds with S. mutabilis significantly increased the shoot and root (radicle) length as well as root hair lengths, relative to the non-inoculated control. In the second experiment, rice plants inoculated with S. mutabilis and grown in rootbox with soil generally had greater total root length under drought regardless of the timing of inoculations, relative to the non-inoculated control. Consequently, improved root system development contributed to the increase in soil water uptake under drought and thus, dry matter production. Among inoculation treatments, one-time inoculation of S. mutabilis either at pre-germination or pre-drought stress at 14 days after sowing (DAS), had significantly greater shoot dry matter production than three-time inoculation at pre-germination, at thinning (3 DAS) and at pre-drought (14 DAS). This study demonstrated the effectiveness of rhizobacteria (S. mutabilis) containing growth promoting compounds for enhancing drought dehydration avoidance root traits and improving the growth of rice plants under drought condition.

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Biological behavior and Treatment of Adenoid Cystic Carcinoma in The Bead and Neck (두경부 선낭암의 생물학적 특성과 치료)

  • Oh W. Y.;Cho K. H.;Suh C. O.;Kim G. E.
    • Radiation Oncology Journal
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    • v.2 no.2
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    • pp.191-202
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    • 1984
  • Biological behavior and treatment results of 33 patients with Adenoid Cystic Carcinoma (ACC) in the Head and Neck at Yonsei Cancer Confer for 10 years between 1971 and 1980 were retrospectively analysed. Most common, primary site was minor salivary glands such as maxillary sinus, nasal cavity and base of tongue. The typical biological behavior of these tumors was very slowly in growth with long time of duration(mean 19 months) from 1 month to 10 years and more frequent of nerve invasion but rare invasion of neck nodes. Local control and failure pattern in the results of treatment, 16 of 17 patients with irradiation alone were seen complete or partial response but 5 cases of locoregional recurrence, 2 cases of failure of neck node and 4 cases of distant metastasis as lung and brain. On the other hand, among 10 cases of surgery and postoperative irradiation, 2 cases of locoregional failure and 3 cases of distant metastasis as lung and bone. 2 of 4 cases with surgery alone were recurred within primary site. Actuarial overall NED survival at 3 ana 10 years were $52.6\%$ and $42.8\%$, respectively. Survival rate of 10 Patients with surgery and Postoperative irradiation was more high than 17 Patients of radiation alone. Therefore, we have known that surgery with postoperative adjunctive irradiation is most effective treatment modality of adenoid cystic carcinoma in the head and neck. Primary site, treatment modality and with or without nerve ana bone invasion have influenced on prognosis.

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