• Journal of the Korean Society of Tobacco Science
• /
• v.20 no.1
• /
• pp.19-25
• /
• 1998

The bulk curing experiment to the improve the quality of flue-cured leaves were carried out to evaluate relationship between cyclic curing and conventional curing method. We studied the effect of the cyclic change of wet bulb temperature at the yellowing stage of flue curing on chemical properties of cured leaves. The wet bulb temperature was automatically controlled between preset high($38^{\circ}C$) and low point ($35^{\circ}C$) everyone hour cyclically during 12 hours after starting luring. As a result, the acceleration of the increase in the chemical properties of cured leaves were observed. As to the chemical properties, there was decreased in citric acid, increased in malic acid of the nonvolatile organic acids and all higher fatty acids content of leaves cured by this method compared with in that of conventional curing method, while a major chemical compounds in relation to aromatic essence of cigarette smoke in essential oil components of lured leaves was mostly higher in this method than those of conventional ones, and it was evaluated that there was decreased in CO, TPM, Tar, and $CO_2$ content of the cigarette smoke comparing to the conventional luring method.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.481-484
• /
• 2004

This study was performed to analyze effect of cyclic load during CFS curing on the behavior of RC beam strengthened with CFS. In the experiment, five different beginning times of cyclic load and two different strengthening amounts of CFS were chosen for experiment parameters. From the experimental results, it could be known that the cyclic load during CFS curing might give detrimental effects to the CFS strengthening effects compared to without cyclic load cases.

• Journal of the Korean Society of Tobacco Science
• /
• v.20 no.1
• /
• pp.13-18
• /
• 1998

In the flue curing process, the wet bulb temperature is usually controlled at a constant level. To improve the quality of flue cured leaves, we studied the effect of the cyclic change of wet bulb temperature at the yellowing stage of flue curing on physical properties of cured leaves. The wet bulb temperature was automatically controlled between preset high (38℃) and low point (35℃) every one hour cyclically. As a result, the acceleration of the increase in the physical properties of cured leaves were observed. The leaves cured by this method were more or less orange in color, better bodied, and less brittle compared with the leaves produced by conventional curing. However, the leaves cured by this method had a little sharpness and harshness. As to the physical properties, there was decreased in occurrence of flat leaves than that of conventional ones. On the other hand, in case of cyclic curing method, increase of price per kg reached to 2-3% compared with those of conventional ones.

• Corrosion Science and Technology
• /
• v.9 no.5
• /
• pp.201-208
• /
• 2010

Epoxy coatings cured by different amine based curing agents have been prepared. Atomic force microscopy (AFM) has been used to monitor the surface topology changes of epoxy coatings before and after hygrothermal cyclic test. The glass transition temperature ($T_g$) and coefficient of thermal expansion (CTE) of the epoxy coating were measured by Thermo-mechanical Analysis (TMA). The Electrochemical impedance spectroscopy (EIS) with hygrothermal cyclic test has been introduced to evaluate the corrosion protection of the epoxy coatings. In conclusion, thermal properties of epoxy coatings were in good agreement with the results of corrosion protection of epoxy coated carbon steel obtained result by EIS with hygrothermal cyclic test. The relationship between thermal properties, surface roughness changes and corrosion protection of epoxy coatings are discussed in this study.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.5
• /
• pp.63-71
• /
• 2010

This paper is about a research of steam curing which is one of the curing methods for accelerating the early-age strength of pre-cast concrete. With cylinder mold and mock-up specimen, the research was executed to study the best cycle of steam curing temperature through quantifying cycle of steam curing and maximum temperature, while the required strength is developed under the early-age. Moreover, causes and measurements for the high temperature of concrete, which is due to the steam curing, and the crack, which occurs when removing steel form, are stated. Ultimately, the economical method of producing, which satisfies early-age strength development and quality assurance while manufacturing PC structure, is stated.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.8
• /
• pp.2272-2278
• /
• 2010

A new hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) is prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with Epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. The resulting compound possesses both the oxirane ring and maleimide group. The curing reaction of these maleimidophenyl glycidylether epoxy compound (N-MPGE) with amines as curing agents such as ethylendiamine (EDA), diethylentriamine (DETA) and triethylenetetramine (TETA), aminoethylpiperazine (AEP) and isophoronediamine, IPDA), are studied. Incorporation of maleimide groups in the epichlorohydrin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples exhibited good thermal stability, excellent chemical (acid/alkali/solvent) and water absorption resistance. Morphological studies by the SEM technique further confirmed the phase homogeneity net work of the cured systems.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.10
• /
• pp.1542-1548
• /
• 2006

Maleimide modified epoxy compounds were prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with diglycidylether of bisphenol-A. Triphenylphosphine was used as catalyst and methylethylketone as solvent. The resulting compound possessed both the oxirane ring and maleimide group. The curing reaction of the maleimide epoxy compound with amine curing agents such as 1-(2-aminoethyl) piperazine (AEP) and 5-amino-1,3,3-trimethylcyclohexane methylamine isophorone diamine, IPDA) were studied. Incorporation of maleimide groups in the epoxy resin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples were found to have good thermal stability, chemical resistance (acid/alkali/solvent) and water absorption resistance.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.11a
• /
• pp.63-64
• /
• 2014

In this study, we has a purpose to estimate the joint movement responsiveness performance for the domestic products of one-component structural silicon sealants. For this purpose, we make a comparative study for the four domestic products focused on tensile properties after allowed the cyclic-movements for three days at initial step of curing phase. A joint movement range ±10% and the rate of compression and extension 3.2mm/h were assumed in those tests. As a result, the large space were induced inside the sealant by rupture, and then adhesion and cohesion failures were caused by stress concentration. The tensile properties were reduced by 15~60% in comparison with physical properties. In this case, the generating defect was caused and the service-life was decreased. Thus, further researches as relationship of test condition and products properties on this behavior would be studied.

• Corrosion Science and Technology
• /
• v.7 no.6
• /
• pp.344-349
• /
• 2008

Epoxy coatings were prepared to give a different corrosion protection by reacting it with two different kinds of curing agent, and then effects of the curing agents on the structure, surface hydrophobic tendency, water transport behavior and hence corrosion protection of epoxy coatings were examined using hygrothermal cyclic test, and impedance analysis. In the results of EIS, the corrosion protection of epoxy coating cured by polyamide shows better than epoxy coating cured by polyamide epoxy adduct. It was well agreed with its water transport behavior and hydrophobic tendency.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.233-236
• /
• 2006

A dilatometer was used to investigate the effect of cure conditions and the presence of filler in an epoxy system. These studies showed shrinkage in the cured epoxy when heating it through the glass transition temperature region. The magnitude of the shrinkage, related to stress build up in the epoxy during curing, was influenced by the processing conditions, filler presence and the nature of the mold used to contain the resin. Cure and cyclic cure at a lower temperature, prior to a post cure, decreased the magnitude of observed shrinkage. Cure shrinkage decreased with number of cyclic cure. Post cured samples outside the mold led to less shrinkage compared with sample in the mold. And sample containing kaolin filler showed less shrinkage than unfilled sample.