• 한국결정성장학회지
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• 제31권4호
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• pp.174-181
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• 2021

순환자원인 IGCC 슬래그와 Si 슬러지를 활용하여 경량 지오폴리머를 제작하였다. 양생방법 및 침지기간에 따른 압축강도 및 밀도의 변화를 관찰하기 위해 세 가지 양생 방법을 시도하였고, 장기공용성 확인을 위해 침지 기간을 21일까지 변화시켰다. Oven(건조기) 양생 시편의 경우, 침지 기간이 증가할수록 압축 강도가 급격하게 감소하였다. 오토클레이브(autoclave)에서 양생된 시편은 3일과 7일에서는 낮은 압축 강도를 보이다 21일에서 급격한 증가를 보인 반면, 오토클레이브에서 양생 후 oven에서 양생한 시편은 반대로 3일과 7일에서 높은 압축 강도를 보였으나, 21일에서 급격한 감소를 보였다. 따라서 초기강도 발현을 위해서는 oven을 이용한 양생이 효과적이나, 장기간 물에 침지할 경우에는 오토클레이브를 이용한 양생이 바람직 한 것으로 사료되었다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1429-1434
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• 2009

Recently electronic circuit pattern printing technologies like antennas of RFID process are paid attention. oven drying system is being used since drying and curing time of RFID Tag Gravure printing normally takes from 5 minutes and up to 30 minutes long. In this case the parental material which is of a sheet shape is possible, however, for a massive and a continuous production drying and curing process must be done on-line. This research compared and analyzed the an oven type drying device and a traditional hot-air drying device. Considering the experiment result, the cell depth that shows low resistivity, which doesn't consider the pattern difference, is $31{\sim}33{\mu}m$. Also, oven drying system showed some resistivity after around 120 seconds of drying time, and showed much better performance in minimum resistivity compared to the hot-air drying system.

• Advances in concrete construction
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• 제9권3호
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• pp.227-234
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• 2020

Raw perlite is a volcanic alumino-silicate and is used as aggregate in the construction industry. The high silica and alumina contained in the raw perlite allows the production of geopolymer mortar with the help of alkaline solutions. In this study, different geopolymer mortars are obtained by mixing ground perlite (GP), sodium hydroxide (NaOH), water and CEN standard sand and the strength and microstructure of these mortars are investigated. Mortar specimens are placed in the oven 24 hours after casting and kept at different temperatures and times, then the specimens are cured under laboratory conditions until the day of strength tests. After curing, unit weight, ultrasound pulse velocity, flexural and compressive strengths are determined. Experimental results indicate that the mechanical properties of the mortars enhance with increasing oven-curing period and temperatures as well as increasing NaOH molarity. In addition, SEM/EDS and XRD analyses are performed on the mortar specimens and the results are interpreted.

• 한국전기전자재료학회논문지
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• 제25권10호
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• pp.844-848
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• 2012

Encapsulant curing in terms of convection oven leads to thermal induced stress due to nonuniform thermal conductivity in LED package. We have adopted infrared (IR) light for silicone curing in order to release the stress. The light uniformity irradiated on an encapsulant surface is confirmed to be uniform by optical simulation. Shear strength of die paste using IR compared to convection oven is increased 19.2% at the same curing time, which indicates curing time can be shortened. The indentation depth difference between center and edge of silicone encapsulant in terms of convection oven and IR are 14.8% and 3.4%, respectively. Curing by IR also shows 2.3% better radiant flux persistency rate of LED at $85^{\circ}C$ after 1,000 h reliability test compared to convection curing.

• Computers and Concrete
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• 제21권2호
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• pp.157-166
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• 2018

This article presents the flexural behaviour of reinforced fly ash (FA)-based geopolymer concrete (GPC) beams with partial replacement of FA for about 10% by weight with paper sludge ash (PSA). The beams were made of M35 grade concrete and cured under three curing conditions for comparison viz., ambient curing, external exposure curing, and oven curing at $60^{\circ}C$. The beams were experimentally tested at the 28th day of casting after curing by conducting two-point loading flexural test. Performance aspects such as load carrying capacity, first crack load, load-deflection and moment-curvature behaviours of both types of beams were experimentally studied and their results were compared under different curing conditions. To verify the response of reinforced GPC beams numerically, an ANSYS 13.0 finite element program was also used. The result shows that there is a good agreement between computer model failure behaviour with the experimental failure behaviour.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.75-79
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• 2008

In this paper, we measured the activation energy of the Bisphenol A type Epoxy resin (DGEBA)-Jeffamine system according to an irradiation. We put the mixed solutions to the silicon mold after mixing both DGEBA(216g) and Jeffamine(93.9g), curing agent of amine system. The mixed solutions were cured in the atmosphere during 24hours after finishing the first curing during 4hours in the vacuum oven under $80^{\circ}C$. The mixed solutions were cured in the atmosphere during 24hours after finishing the second curing during 12hours in the vacuum oven under $60^{\circ}C$ again. Prepared samples were irradiated to the dose rate of 8kGy/hr with 500kGy, 700kGy, 1000kGy, 1500kGy, 2000kGy, 2500kGy. Experimental results indicated activation energy of the samples reduced as the irradiation dose increased because of the peroxides of the Epoxy created by the oxidation and the radiation.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.73-78
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• 2010

This research is about the drying and curing characteristic of conductivity metallic ink on-line curing device in order to improve the curing time for productivity in RFID Gravure printing. The curing process is carried out to increase the electric conductivity after the metallic ink is printed on the substrate. The metal ink is composed of nano-sized silver or copper particles. In this research, the combined IR and Hot air curing system is used and its results is compared with those of oven, IR and Hot Air type respectively. Generally the curing time in the past is about 3 minutes. But the combined system (IR+Hot Air) in this research shows that curing time is less than 30 seconds. These results is much faster than those of other system. This study can be help to make Roll-to-Roll drying and curing process for mass and continuous production on-line.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.105-110
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• 2001

Autoclave curing using the vacuum bagging method is widely used for the manufacture of advanced composite prepreg airframe structures. Due to increasing use of advanced composites, specific techniques have been developed to repair damaged composite structures. In order to repair the damaged part, it is required that the damaged areas be removed, such as skin and/or honeycomb core, by utilizing the proper method and then repairing the area by laying up prepreg (and core) then curing under vacuum using the vacuum bagging materials. It shall be cured either in an oven or autoclave per the original specification requirements. Delamination can be observed in the sound areas during and/or after a couple times exposure to the elevated curing temperature due to the repeated repair condition. This study was conducted for checking the degree of degradation of properties of the cured parts and delamination between skin prepreg and honeycomb core. Specimens with glass honeycomb sandwich construction and glass/epoxy prepreg were prepared. The specimens were cured 1 to 5 times at $260^{circ}F$ in an autoclave and each additionally exposed 50, 100 and 150 hours in the $260^{circ}F$ oven. Each specimen was tested for tensile strength, compressive strength, flatwise tensile strength and interlaminar shear strength. To monitor the characteristics of the resin itself, the cured resin was tested using DMA and DSC. As a results, the decrease of Tg value were observed in the specific specimen which is exposed over 50 hrs at $260^{circ}F$. This means the change or degradative of resin properties is also related to the decrease of flatwise tensile properties. Accordingly, minimal exposure on the curing temperature is recommended for parts in order to prevent the delation and maintain the better condition.

• Advances in concrete construction
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• 제9권5호
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• pp.449-457
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• 2020

The influence of subsequent curing on the performance of fly ash contained mortar under steam curing was studied. Mortar samples incorporated with different content (0%, 20%, 50% and 70%) of Class F fly ash under five typical subsequent curing conditions, including standard curing (ZS), water curing(ZW) under 25℃, oven-dry curing (ZD) under 60℃, frozen curing (ZF) under -10℃, and nature curing (ZN) exposed to outdoor environment were implemented. The unsteady chloride diffusion coefficient was measured by rapid chloride migration test (RCM) to analyze the influence of subsequent curing condition on the resistance to chloride penetration of fly ash contained mortar under steam curing. The compressive strength was measured to analyze the mechanical properties. Furthermore, the open porosity, mercury intrusion porosimetry (MIP), x-ray diffraction (XRD) and thermogravimetric analysis (TGA) were examined to investigate the pore characteristics and phase composition of mortar. The results indicate that the resistance to chloride ingress and compressive strength of steam-cured mortar decline with the increase of fly ash incorporated, regardless of the subsequent curing condition. Compared to ZS, ZD and ZF lead to poor resistance to chloride penetration, while ZW and ZN show better performance. Interestingly, under different fly ash contents, the declining order of compressive strength remains ZS>ZW>ZN>ZD>ZF. When the fly ash content is blow 50%, the open porosity grows with increase of fly ash, regardless of the curing conditions are diverse. However, if the replacement amount of fly ash exceeds a certain high proportion (70%), the value of open porosity tends to decrease. Moreover, the main phase composition of the mortar hydration products is similar under different curing conditions, but the declining order of the C-S-H gels and ettringite content is ZS>ZD>ZF. The addition of fly ash could increase the amount of harmless pores at early age.

• Advances in concrete construction
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• 제5권4호
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• pp.313-330
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• 2017

Geopolymer is a sustainable concrete, replaces traditional cement concrete using alternative sustainable construction materials as binders and alkaline solution as alkaline activator. This paper presents the strength characteristics of geopolymer concrete (GPC) developed with fly ash and GGBS as binders, combined Sodium silicate ($Na_2SiO_3$) and Sodium Hydroxide (NaOH) solution as alkaline activators. The parameters considered in this research work are proportions of fly ash and GGBS (70-30 and 50-50), curing conditions (Outdoor curing and oven curing at $600^{\circ}C$ for 24 hours), two grades of concrete (GPC20 and GPC50). The mechanical properties such as compressive strength, split tensile strength and flexural strength along with durability characteristics were determined. For studying the durability characteristics of geopolymer concrete 5% $H_2SO_4$ solutions was used and the specimens were immersed up to an exposure period of 56 days. The main parameters considered in this study were Acid Mass Loss Factor (AMLF), Acid Strength Loss Factor (ASLF) and products of degradation. The results conclude that GPC with sufficient strength can be developed even under Outdoor curing using fly ash and GGBS combination i.e., without the need for any heat curing.