Temperature development and cracking characteristics of high strength concrete slab at early age

Chung-Hao Wu,Yu-Feng Lin,Shu-Ken Lin,Chung-Ho Huang 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.6

High-strength concrete (HSC) generally is made with high amount of cement which may release large amount of hydration heat at early age. The hydration heat will increase the internal temperature of slab and may cause potential cracking. In this study, slab specimens with a dimension of 600 × 600 × 100 mm were cast with concrete incorporating silica fume for test. The thermistors were embedded in the slabs therein to investigate the interior temperature development. The test variables include water-to-binder ratio (0.25, 0.35, 0.40), the cement replacement ratio of silica fume (RSF; 5 %, 10 %, 15 %) and fly ash (RFA; 10 %, 20 %, 30 %). Test results show that reducing the W/B ratio of HSC will enhance the temperature of first heat peak by hydration. The increase of W/B decrease the appearance time of second heat peak, but increase the corresponding maximum temperature. Increase the RSF or decrease the RFA may decrease the appearance time of second heat peak and increase the maximum central temperature of slab. HSC slab with the range of W/B ratio of 0.25 to 0.40 may occur cracking within 4 hours after casting. Reducing W/B may lead to intensive cracking damage, such as more crack number, and larger crack width and length.

The Effect of CdS QDs Structure on the InGaP/GaAs/Ge Triple Junction Solar Cell Efficiency

Chen-Chen Chung,Binh Tinh Tran,Hau-Vei Han,Yen-Teng Ho,Hung-Wei Yu,Kung-Liang Lin,Hong-Quan Nguyen,Peichen Yu,Hao-Chung Kuo,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2

This work describes optical and electrical characteristics of InGaP/GaAs/Ge triple-junction (T-J) solar cells with CdS quantum dots (QDs) fabricated by a novel chemical solution. With the anti-reflective feature at long wavelength and down-conversion at UV regime, the CdS quantum dot effectively enhance the overall power conversion efficiency more than that of a traditional GaAs-based device. Experimental results indicate that CdS quantum dot can enhance the short-circuit current by 0.33 mA/cm2, which is observed for the triple-junction solar cells with CdS QDs of about 3.5 nm in diameter. Moreover, the solar cell conversion efficiency is improved from 28.3% to 29.0% under one-sun AM 1.5 global illumination I-V measurement.

The properties of hydrophobic concrete prepared by biomimetic mineralization method

Chung-Ho Huang,Hao-Yu Fang,Jue-Zhong Zhang 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.5

In this study, the calcium hydroxide, an inherent product of cement hydration, was treated using biomimetic carbonation method of incorporating stearic acid to generate the hydrophobic calcium carbonate on concrete surface. Carbonation reaction was carried out at various CO2 pressure and temperatures and utilizing the Scanning Electron Microscope (SEM), chloride-ion penetration test apparatus, and compression test machine to investigate the hydrophobicity, durability, and mechanical properties of the synthesized products. Experimental results indicate that the calcium stearate may change the surface property of concrete from hydrophilicity to hydrophobicity. Increasing reaction temperature can change the particles from irregular shapes to needle-rod structures with increased shear stress and thus favorable to hydrophobicity and microhardness. The contact angle against water for the concrete surface was found to increase with increasing CO2 pressure and temperature, and reached to an optimum value at around 90°C. The maximum static water contact angle of 128.7 degree was obtained at the CO2 pressure of 2 atm and temperature of 90°C . It was also found that biomimetic carbonation increased the permeability, acid resistance and chloride-ion permeability of the concrete material. These unique results demonstrate that the needle-rod structures of CaCO3 synthetized on concrete surface could enhance hydrophobicity, durability, and mechanical properties of concrete.

Improvement of bond strength and durability of concrete incorporating high volumes of class F fly ash

Wu, Chung-Hao,Chen, Chien-Jung,Lin, Yu-Feng,Lin, Shu-Ken Techno-Press 2021 Advances in concrete construction Vol.12 No.5

This study experimentally investigated the improvement of bond strength and durability of concrete containing high volume fly ash. Concrete mixtures made with 0%, 25% and 60% replacement of cement with class F fly ash were prepared. Water-binder ratios ranged from 0.28 to 0.72. The compressive, flexural and pullout bond strength, the resistance to chloride-ion penetration, and the water permeability of concrete were measured and presented. Test results indicate that except for the concretes at early ages, the mechanical properties, bond strength, and the durability-related chloride-ion permeability and water permeability of concrete containing high volume (60% cement replacement) fly ash were obviously superior to the concrete without fly ash at later ages of beyond 56 days. The enhanced bond strength for the high volume fly-ash concrete either with or without steel confinement is a significant finding which might be valuable for the structural application.

Entomopathogenic fungi-mediated biological control of the red palm weevil Rhynchophorus ferrugineus

Yang Tzu-Hao,Wu Li-Hsin,Liao Chung-Ta,LIDONGWEI,Young Shin Tae,Jae Su Kim,Nai Yu-Shin 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.1

The red palm weevil (RPW), Rhynchophorus ferrugineus, is an important pest of palms, and difficult to control by conventional methods. Therefore, microbial control is an alternative strategy for controlling RPW. Herein, a total of 15 entomopathogenic fungi (EPFs) were subjected to primary pathogenicity screening against last stage of RPW larvae. The preliminary data showed that four Beauveria bassiana isolates (JEF-484, 158, 462 and 507) and one Isaria fumosorosea isolate (JEF-014) resulted in 100 % mortality within 5–10 days post inoculation (d.p.i.), respectively. According to the time required for RPW mortality, JEF-484, 158, 462 and 014 were further sub jected to bioassays using 10 7 conidia/ml suspensions by spraying method. Based on the results, JEF-484 showed the highest mortality and shortest LT 50 on the last stage of RPW larvae, followed by JEF-158. The two isolates also showed good conidial production and high thermal stability compared to the other isolates. Therefore, JEF-484 and JEF-158 were selected for bioassays against RPW egg and the last larval stage with different concen trations of 10 5 , 10 6 and 10 7 conidia/ml conidial suspensions by spraying method. For the bioassay at the egg stage, JEF-158 showed a significantly higher ovicidal effect than JEF-484. In the larval bioassay, both EPF isolates showed a dosage-dependent effect on the RPW larvae. JEF-484 caused higher mortality in RPW larvae than JEF-158. In summary, the combination of the 2 promising EPF isolates might provide an opportunity for the practical microbial control of RPW at different life stages in palm tree fields.

Shear behavior of reinforced HPC beams made of a low cement content without shear reinforcements

Chao-Wei Tang,Yu-Ping Chen,How-Ji Chen,Chung-Ho Huang,Tsang-Hao Liu 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.1

High-performance concrete (HPC) usually has higher paste and lower coarse aggregate volumes than normal concrete. The lower aggregate content of HPC can affect the shear capacity of concrete members due to the formation of smooth fractured surfaces and the subsequent development of weak interface shear transfer. Therefore, an experimental investigation was conducted to study the shear strength and cracking behavior of full-scale reinforced beams made with low-cement-content high-performance concrete (LcHPC) as well as conventional HPC. A total of fourteen flexural reinforced concrete (RC) beams without shear reinforcements were tested under a two-point load until shear failure occurred. The primary design variables included the cement content, the shear span to effective depth ratio (a/d), and the tensile steel ratio (ρw). The results indicate that LcHPC beams show comparable behaviors in crack and ultimate shear strength as compared with conventional HPC beams. Overall, the shear strength of LcHPC beams was found to be larger than that of corresponding HPC beams, particularly for an a/d value of 1.5. In addition, the crack and ultimate shear strength increased as a/d decreased or ρw increased for both LcHPC beams and HPC beams. This investigation established that LcHPC is recommendable for structural concrete applications.

IBM Zigbee Positioning Method for Smart Home Applications

Ming-Hui Jin,Chung-Jung Fu,Chih-Hao Yu,Hung-Ren Lai,Ming-Whei Feng 보안공학연구지원센터 2008 International Journal of Smart Home Vol.2 No.2

This paper presents a smart home system prototype which employs an indoor positioning system called the III Beacon Match (I3BM) positioning method to intelligently trigger the appropriately services for the home members. To overcome the ninja problem in the I3BM method, the signal filtering, adjustment and smooth procedures are proposed. The proposed system prototype employs the Zigbee module to implement the prototypes of the components for the I3BM positioning method, and the prototypes had passed the ZigBee Compliant Platform (ZCP) certification test. The proposed system prototype which intelligently controls the air condition and light system for smart home applications is also verifying in our demo room and in the smart house in National Taiwan University.

Field Performance and Morphological Characterization of Transgenic Codonopsis lanceolata Expressing γ-TMT Gene.

Bimal Kumar Ghimire,Cheng Hao Li,Hyun-Young Kil,Na-Young Kim,Jung-Dae Lim,Jae-Kwang Kim,Myong-Jo Kim,Ill-Min Chung,Sun-Joo Lee,Seok-Hyun Eom,Dong-Ha Cho,Chang-Yeon Yu 한국약용작물학회 2007 한국약용작물학회지 Vol.15 No.5

Field performance and morphological characterization was conducted on seven transgenic lines of Codonopsis lanceolata expressing γ-TMT gene. The shoots were obtained from leaf explants after co-cultivation with Agrobacterium tume-faciens strain LBA 4404 harboring a binary vector pYBI 121 that carried genes encoding γ-Tocopherol methyltransferase gene (γ-TMT) and a neomycin phosphotransferase II gene (npt II) for kanamycin resistance. The transgenic plants were transferred to a green house for acclimation. Integration of T-DNA into the T0 and T1 generation of transgenic Codonopsis lanceolata genome was confirmed by the polymerase chain reaction and southern blot analysis. The progenies of transgenic plants showed phenotypic differences within the different lines and with relative to control plants. When grown in field, the transgenic plants in general exhibited increased fertility, significant improvement in the shoot weight, root weight, shoot height and rachis length with relation to the control plants. However, all seven independently derived transgenic lines produced normal flower with respect to its shape, size, color and seeds number at its maturity. Indicating that the addition of a selectable marker gene in the plant genome does not effect on seed germination and agronomic performance of transgenic Codonopsis lanceolata. T1 progenies of these plants were obtained and evaluated together with control plant in a field experiment. Overall, the agronomic performance of T1 progenies of transgenic Codonopsis lanceolata showed superior to that of the seed derived non-transgenic plant. In this study, we report on the morphological variation and agronomic performance of transgenic Codonopsis lanceolata developed by Agrobacterium transformation.

Empty nose syndrome treated by autologous auricular cartilage turbinate augmentation: a case report

Wu Tzu-I,Hao Chung-Yu,Chiu Yu-Hsun 대한미용의학회 2021 대한미용의학회지 Vol.5 No.2

Empty nose syndrome (ENS), once viewed as a psychological issue, is now a recognized complication of turbinate surgery. It is most frequently associated with total turbinate excision. Its symptoms include chronic dryness of the nose and pharynx, paradoxical obstruction of the nose, feeling of suffocation, lack of airflow sensation, and even neuropathic pain. It may cause severe stress upon the patient resulting in mood instability issues. Surgical treatment to augment turbinate volume has been reported to be an effective treatment method. We would like to report a case of ENS treated by autologous auricular cartilage turbinate augmentation.

Effect of Gibberellin and Light on Germination of Seeds in Codonopsis lanceolata Benth

Bimal Kumar Ghimire,Chul-Min Shin,Cheng-Hao Li,Ill-Min Chung,Dong-Wook Lee,Hee-Young Kim,Na-Young Kim,Jung-Dae Lim,Jae-Kwang Kim,Myong-Jo Kim,Dong-Ha Cho,Sun-Joo Lee,Chang-Yeon Yu 한국약용작물학회 2006 한국약용작물학회지 Vol.14 No.5

Seed of Codonopsis lanceolata exhibits low germination due to impermeable seed coat. Prolonged seed dormancy can be overcome by the application of gibberellins, as it promotes growth of the embryo and weakens the structures surrounding of embryo. The effects of photoperiod, sugar and gibberellin concentration were investigated at constant temperature for 12 days and 22 days in vitro and invivo conditions respectively. The rate of germination of seeds of Codonopsis lanceolata in wet filter paper in both complete dark and light treatments was significantly lower than that of seed treated with GA3. It clearly indicates that there is significant coat imposed dormancy in the seed of Codonopsis lanceolata. The rate of germination in vivo condition was lower than that of the in vitro condition supplemented with GA3 Thus, the physical dormancy due to impermeable seed coat and low level of endogenous gibberellins in the seed was the cause of poor germination rate in Codonopsis lanceolata.