• 한국세라믹학회지
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• 제15권4호
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• pp.205-212
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• 1978

The hydration reaction of the slag-gypsum system was studied by X-ray diffraction, differential thermal analysis, optical icroscopic observation, and measurement of heat liberation of hydration. 1. Domestic granulated slag was almost noncrystalized state, and its mineral compositions calculated were 46.53% of gehlenite, 28.14% of akermanite, and 19.04% of wollastonite. 2. The slag quenched with water at relatively high temperature had better reactivity. 3. The production of ettringite, CSH gel and AH3 gel were stimulated by effect of $Ca(OH)_2$, $Mg(OH)_2$ and calcined dolomite as activators, and the strength of hardened body would be developed by forming compacted microstructure.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1069-1084
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• 2014

The long-term performance of plates resting on viscoelastic foundations is a major concern in the analysis of soil-structure interaction. As a powerful mathematical tool, fractional calculus may address these plate-on-foundation problems. In this paper, a fractionalized Zener model is proposed to study the time-dependent behavior of a uniformly loaded rectangular thin foundation plate. By use of the viscoelastic-elastic correspondence principle and the Laplace transforms, the analytical solutions were obtained in terms of the Mittag-Leffler function. Through the analysis of a numerical example, the calculated plate deflection, bending moment and foundation reaction were compared to those from ideal elastic and standard viscoelastic models. It is found that the upper and lower bound solutions of the plate response estimated by the proposed model can be determined using the elastic model. Based on a parametric study, the impacts of model parameters on the long-term performance of a foundation plate were systematically investigated. The results show that the two spring stiffnesses govern the upper and lower bound solutions of the plate response. By varying the values of the fractional differential order and the coefficient of viscosity, the time-dependent behavior of a foundation plate can be accurately captured. The fractional differential order seems to be dependent on the mechanical properties of the ground soil. A sandy foundation will have a small fractional differential order while in order to simulate the creeping of clay foundation, a larger fractional differential order value is needed. The fractionalized Zener model is capable of accounting for the primary and secondary consolidation processes of the foundation soil and can be used to predict the plate performance over many decades of time.

• Asian-Australasian Journal of Animal Sciences
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• 제21권3호
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• pp.325-330
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• 2008

In order to understand the molecular mechanism of heterosis of reproduction traits in chickens, we used the quantitative real-time reverse transcriptional polymerase chain reaction (Quantitative real-time RT-PCR) technique to investigate the differential expression of estrogen receptor (ESR) and follicle stimulating hormone receptor (FSHR) genes in 32-week-old ovaries of inbred chickens and their hybrid offspring in $4{\times}4$ diallel crosses, which involved White Plymouth Rock (E), CAU Brown (D), Silkies (C) and White Leghorn (A). We found that there were significant differences in mRNA expression of ESR and FSHR genes not only between hybrids and their parental lines (p<0.01), but also among different crosses (p<0.01). Furthermore, positive correlations between differential expression of both ESR and FHSR in hybrids and heterosis percentages of 32-week-old and 42-week-old egg number traits were significant at p<0.05. Our results suggested that differential expression of ESR and FSHR genes in the ovaries of inbred chickens and their hybrids could play roles in the formation of heterosis of egg number traits to some extent.

• The Plant Pathology Journal
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• 제16권3호
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• pp.142-146
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• 2000

Ordered differential display using RT-PCR (ODD-PCR) was conducted to have a profile of the differently expressed genes between a hypovirulent strain of Cryphonectria parasitica (UEP1) and its isogenic wild type strain (EP155/2). ODD-PCR has advantages of high sensitivity, reproducibility, proportional representation, and limited number of primer combinations comparing with other differential display methods. RNAs were prepared from 1 and 5 day liquid culture of both hypovirulent and wild type strains, and were further evaluated with the marker genes of C. parasitica such as cryparin and mating factor MF2-1, which were already proven to be specifically down-regulated by the presence of mycovirus CHV1-713. ODD-PCR was conducted using those RNAs and expressed genes were categorized to five groups according to their temporal and quantitative expression patterns. Those fives groups are CPC, CPE, CPL, CPD, and CPU which represent constitutively-expressed, early-expressed, late-expressed, down-regulated, and up-regulated, respectively. Ninety two primer combinations out of a total of 192 have been tested so far. Among the twenty to fifty distinct bands per each reaction, an average of four to ten genes was identified as viral-regulated fungal genes. Those viral-specifc genes were further analyzed by DNA sequencing followed by homology search. Characterization of 30 clones including all five groups were conducted as a preliminary data and more are under investigation.

• Restorative Dentistry and Endodontics
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• 제42권2호
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• pp.111-117
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• 2017

Objectives: Periapical lesions, including periapical cyst (PC), periapical granuloma (PG), and periapical abscess (PA), are frequently affected by chemical/physical damage during root canal treatment or severe bacterial infection, and thus, the differential diagnosis of periapical lesions may be difficult due to the presence of severe inflammatory reaction. The aim of this study was to make differential diagnosis among PC, PG, and PA under polarizing microscope. Materials and Methods: The collagen birefringence patterns of 319 cases of PC (n = 122), PG (n = 158), and PA (n = 39) obtained using a polarizing microscope were compared. In addition, 6 cases of periodontal fibroma (PF) were used as positive controls. Results: Collagen birefringence was condensed with a thick, linear band-like pattern in PC, but was short and irregularly scattered in PG, and scarce or absent in PA. PF showed intense collagen birefringence with a short, palisading pattern but no continuous band-like pattern. The linear band-like birefringence in PC was ascribed to pre-existing expansile tensile stress of the cyst wall. Conclusions: In this study all PCs (n = 122) were distinguishable from PGs and PAs by their characteristic birefringence, despite the absence of lining epithelium (n = 20). Therefore, the authors suggest that the presence of linear band-like collagen birefringence of the cyst wall aids the diagnostic differentiation of PC from PG and PA.

• 한국수소및신에너지학회논문집
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• 제16권3호
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• pp.262-268
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• 2005

[ $Zn(BH_4)_2$ ](8.4 wt% theoretical hydrogen storage capacity powders have been successfully synthesized by mechanochemical reaction from mixtures of $ZnCl_2$ and $NaBH_4$ powders in a 1:2 molar ratio in different times. $$ZnCl_2+2NaBH_4{\rightarrow}Zn(BH_4)_2+2NaCl$$ (1) $Zn(BH_4)_2$ powders were characterized by X-ray diffractometry(XRD), and Furier Transform Infrared spectrometry(FT-IR). The thermal stabilities of $Zn(BH_4)_2$ powders were studied by Differential scanning calorimetry(DSC), Thermogravimetry analysis(TGA), and Mass spectrometry(MS). $Zn(BH_4)_2$ can be tested for hydrogen evolution without further purification. The reaction to yield hydrogen is irreversible, the other products being compounds of Zn, and borane. $Zn(BH_4)_2$ thermally decomposes to release borane and hydrogen gas between about 85 and 150$^{\circ}C$.

• 한국결정성장학회지
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• 제8권1호
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• pp.138-144
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• 1998

에탄올을 용매로 사용한 철질산염(Fe$(MO_3)_3{\cdot}9H_2O$) 용액의 가용매분해 및 중합반응을 거친후 $350^{\circ}C$의 온도로 열처리를 하여 0.5$\alpha$m이하의 크기를 갖는 $\alpha$-$Fe_2O_3$ 미분말을 합성하였다. 반응시간에 따른 pH 변화와 적외선 분광 분석을 통해 용액내의 반응을 규명하였으며, 열분석(DSC), X-선 회절분석 및 적외선 분광(FT-IR) 분석을 통해 $\alpha$-$Fe_2O_3$가 형성되는 분해과정에 대해 분석하였다. 또한 반응온도와 철질산염의 농도를 변화시켜 각각 $\alpha$-$Fe_2O_3$분말의 입자크기에 미치는 영향을 조사하였다.

• Design & Manufacturing
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• 제8권2호
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• pp.46-49
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• 2014

Silicone is recently used for LED chip lense due to its good thermal stability and optical transmittance. In order to predict residual stress which causes optical briefringence and mechanical warpage of silicone, finite element analysis was conducted for curing process during silicone molding. For analysis of curing process, a dynamic cure kinetics model was derived based on the differential scanning calorimetry(DSC) test and applied to the material properties for finite element analysis. Finite element simulation result showed that the slow cure reduced abrupt reaction heat and it was predicted decrease of the residual stress.

• Carbon letters
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• 제12권4호
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.

• Fibers and Polymers
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• 제4권1호
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• pp.20-26
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• 2003

The thermal behavior, morphology, ester-interchange reaction of Poly(trimethylene terephthalate) (PTT)/poly(ethylene terephthalate) (PET) melt blends were investigated over the whole composition range(xPTT/(1-x)PET) using a twinscrew Brabender. The melt blends were analyzed by differential scanning calorimetry (DSC), nuclear magnetic resonance spectroscopy ($^{13}{C-NMR}$), and scanning electron microscopy (SEM). Single glass transition temperature ($T_g$) and cold crystallization temperature ($T_cc$) were observed in all melt blends. Melt blends were found to be due to the ester-interchange reaction in PTT/PET blend. Also the randomness of copolymer increases because transesterification between PT and PET increases with increasing blending time This reaction increases homogeneity of the blends and decreases the degree of crystallinity of the melt blends. In PTT-rich blends, mechanical properties decrease with increase of PET content compared with that of pure PTT. And, in PET-rich blends, tensile modulus decreases with increase of PTT content, but tensile strength and elongation is similar to that of pure PET.