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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.
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.
Huang, Peng-Yi,Chen, Liang-Hsiang,Kim, Choongik,Chang, Hsiu-Chieh,Liang, You-jhih,Feng, Chieh-Yuan,Yeh, Chia-Ming,Ho, Jia-Chong,Lee, Cheng-Chung,Chen, Ming-Chou American Chemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.12
<P>Three benzo[<I>d</I>,<I>d</I>′]thieno[3,2-<I>b</I>;4,5-<I>b</I>′]dithiophene (<B>BTDT</B>) derivatives, end-functionalized with benzothiophenyl (<B>BT-BTDT</B>; <B>2</B>), benzothieno[3,2-b]thiophenyl (<B>BTT-BTDT</B>; 3), and benzo[<I>d</I>,<I>d</I>′]thieno[3,2-<I>b</I>;4,5-<I>b</I>′]dithiophenyl (<B>BBTDT</B>; <B>4</B>), were prepared for bottom-contact/bottom-gate organic thin-film transistors (OTFTs). An improved one-pot [2 + 1 + 1] synthetic method of <B>BTDT</B> with improved synthetic yield was achieved, which enabled the efficient realization of new <B>BTDT</B>-based semiconductors. All of the <B>BTDT</B> compounds exhibited high performance p-channel characteristics with carrier mobilities as high as 0.34 cm<SUP>2</SUP>/(V s) and a current on/off ratio of 1 × 10<SUP>7</SUP>, as well as enhanced ambient stability. The device characteristics have been correlated with the film morphologies and microstructures of the corresponding compounds.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-12/am3022448/production/images/medium/am-2012-022448_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am3022448'>ACS Electronic Supporting Info</A></P>
Effect of Be Addition on the Oxidation Behavior of Mg-Ca Alloys at Elevated Temperature
Huang, Yan-Bin,Chung, In-Sang,You, Bong-Sun,Park, Won-Wook,Choi, Byung-Ho 대한금속재료학회 2004 METALS AND MATERIALS International Vol.10 No.1
Beryllium was added to Mg-Ca alloys to study their ignition-proof properties. The ignition temperatures of Mg-2Ca alloys were increased dramatically with increasing Be addition. Thermogravimetric measurement revealed that the oxidation of Mg-2Ca alloys was slowed down by Be addition. After elevated temperature exposure to air, the Mg-2Ca alloy was partially ignited, while the surface of Be-containing alloys was smooth without any partial ignition. SEM, low-angle XRD, and AES observations indicated that the surface of Be- containing alloys became compact and dense, and the oxide film formed at elevated tempemture mainly con- sisted of CaO together with MgO and BeO. It was found that the CaO enriched oxide layer acted as an impermeable barrier to the inward difhsion of oxygen and thus further oxidation was prevented.
Chung, Moon-Soo,Huang, Ping,Ha, Chan-Man,Jun, Ji-Hyung,Ahn, Sung-Ju,Zhang, Fu-Chun,Bae, Hyun-Jong,Cho, Baik-Ho,Kim, Cheol-Soo 한국식물학회 2011 Journal of Plant Biology Vol.54 No.1
We carried out functional analysis of a putative novel Arabidopsis plasma membrane glucose-responsive regulator, designated AtPGR, which contains seven predicted transmembrane domains. Several evidences showed that AtPGR is a glucose-related protein, but its biological functions have yet to be reported in any plant. Analyses of the AtPGR promoter-${\beta}$-glucuronidase (GUS) construct and RNA in situ hybridization revealed substantial gene expression in the vasculature of various tissues, especially in the phloem region. Glucose treatment induced the highest levels of GUS activity, reaching a peak at 3 h and declining thereafter, consistent with glucose-mediated regulation of the AtPGR promoter. We generated an atpgr RNAi knockdown mutant and found that this plant grew and developed normally. Ectopic expression of AtPGR gene modulated the induction of glucose and 2-deoxyglucose insensitivity under stress conditions. By way of contrast, cotyledon greening of atpgr RNAi knockdown mutant seeds enhanced sensitivity to glucose and 2-deoxyglucose. Taken together, these results suggest that AtPGR functions as a potential glucoseresponsive regulator in carbohydrate metabolism.
Experimental investigation on steel-concrete bond in lightweight and normal weight concrete
Chen, How-Ji,Huang, Chung-Ho,Kao, Zhang-Yu Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2
The bonding behaviors of Lightweight Aggregate Concrete (LWAC) and normal weight concrete were investigated experimentally. Pull-out tests were carried out to measure the bond strengths of three groups of specimens with compressive strength levels of 60, 40, and 20 MPa, respectively. Test results showed that the difference in the bond failure pattern between LWAC and normal weight concrete was significant as the concrete compressive strength became lower than 40 MPa. The corresponding bond strengths of LWAC were lower than that for normal weight concrete. As the compressive strength of concrete became relatively high (> 40 MPa), a bond failure pattern in normal weight concrete occurred that was similar to that in LWAC. The bond strength of LWAC is higher than that for normal weight concrete because it possesses higher mortar strength. Stirrup use leads to an increase of approximately 20% in nominal bond strength for both types of concrete at any strength level.
Tsangyao Chang,Yuan-Hong Ho,Chung-Ju Huang 중앙대학교 경제연구소 2007 Journal of Economic Development Vol.32 No.1
In this empirical note we use a more powerful nonlinear (logistic) unit root test advanced by Leybourne et al. (1998) to investigate the hysteresis in unemployment for ten European countries for the period 1961-2003. The hypothesis is confirmed for all the European countries for which Leybourne et al.’s (1998) nonlinear (logistic) unit root test is performed, except for Belgium and the UK.
Pulsed γ-ray emission from magnetar 1E 2259+586
Wu, Jason Hung Kit,Hui, Chung Yue,Huang, Regina Hsiu Hui,Kong, Albert Kwok Hing,Cheng, Kwong Sang,Takata, Jumpei,Tam, Pak Hin Thomas,Wu, Eric Man Ho,Liu, Joe 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.2
Anomalous X-ray pulsars (AXPs) are thought to be magnetars which are young isolated neutron stars with extremely strongmagnetic fields of >1014 Gauss. Their tremendous magnetic fields inferred from the spin parameters provide a huge energyreservoir to power the observed X-ray emission. High-energy emission above 0.3 MeV has never been detected despiteintensive search. Here, we present the possible Fermi Large Area Telescope (LAT) detection of γ-ray pulsations above 200MeV from the AXP, 1E 2259+586, which puts the current theoretical models of γ-ray emission mechanisms of magnetars intochallenge. We speculate that the high-energy γ-rays originate from the outer magnetosphere of the magnetar.