• Journal of the Korean Wood Science and Technology
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• v.32 no.5
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• pp.59-65
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• 2004

The present study aims to optimise the process parameters of fish glue and adhesion property through room temperature in terms of curing time and opened assembly time for attaining best adhesion strength to wood (Yellow birch, B. alleghaniensis). The uncured and cured fish glue have been characterised by TGA, DSC, FT-JR. It is observed that with increasing curing time up to 48 H, tensile lap shear strength of adhesive joint of fish glue to wood increases and decreases after 48 H. At 15 min. opened assembly time, lap shear strength increases up to 4833 kgf/cm² and decreases after 15 min.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.3
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• pp.344-353
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• 2018

The purposes of this study were to evaluate microleakage of Biodentine, one of the tricalcium silicate based pulp-capping materials, and to compare the shear bond strength between composite resin and Biodentine with different setting times. For microleakage evaluation, 70 bovine teeth were used. Cavities were formed on the labial surfaces and filled with Biodentine. The teeth were divided into seven groups, each consisting of 10 teeth. The specimens were prepared by applying the composite resin on the upper side after different setting times. To evaluate shear bond strength, 210 acrylic resin blocks with central grooves were prepared, and the grooves were filled with Biodentine. The acrylic resin blocks were divided into seven groups of 30 specimens each, and the specimens were prepared by applying the composite resin on the upper side after different setting times. In samples with setting time of 24 hours or longer period, the microleakage between composite resin and Biodentine was reduced significantly while the shear bond strength increased to offset the polymerization shrinkage of the composite resin. Setting Biodentine for more than 24 hours before composite resin restoration would lead to more favorable clinical result.

• Korean Journal of Materials Research
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• v.7 no.10
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• pp.827-831
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• 1997

DGEBA/MDA/GN 계의 기계적 및 절연성질에 미치는 후기경화 조건의 영향을 연구하였다. 시편은 8$0^{\circ}C$에서 1.5시간 동안 경화한 후 15$0^{\circ}C$에서의 후기 경화시간과 경화온도를 다르게 하였다. 후기 경화온도가 증가함에 따라 인장강도, 절연파괴 강도 그리고 유리전이온도는 약간 증가하였으나 감소하였다. 4시간까지 후기경화되었을 때 인장강도와 유리전이온도는 증가하였으나 충격강도는 감소하였다. 그러나 4시간 후에는 거의 일정한 값을 나타내었다. 절연파괴 강도는 후기경화 시간에 관계없이 거의 일정한 값을 나타내었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.4
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• pp.24-32
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• 2008

We made a new propellant formulation to improve the productivity of Base Bleed Unit(aka BBU) by reducing of the curing time. We made an experiment with new propellant formulation such as binder characteristics and manufacturing process. In addition, we already tested several basic characteristics and the final performance of the new propellant. According to the test report, it was not only satisfied with all requirements in the specification, but it also contributed to improve productivity and reduced 53% of the curing time.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.237-240
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• 2000

본 연구에서는 비스페놀 A, 에피크로로히트린을 반응시킨 에폭시 기본주제를 중심으로 경화제, 희석제, 충진제, 촉매 등을 배합하여 토목, 건축용 반고체형 에폭시 접착제를 개발하였다. 여기서 특히 에폭시 주제와 희석제의 종류 및 배합비율에 따른 기본 물성, 접착성능 등을 측정하였다. 상온 경화 특성을 측정하기 위하여 경화시 간을 측정한 결과 희석제의 종류와 관계없이 희석제의 양이 증가할수록 경화시간이 증가하고 경화온도도 증가하는 경향을 알 수 있었으며 촉매의 양이 적을 경우가 경화시간이 빠른 것을 알 수 있었다. 또한 경화 시간은 30분 내지 40분 정도로 상온에서 사용할 수 있을 것으로 기대한다. 접착력 시험 결과는 촉매의 양이 적당한 때 가장 좋은 접착력을 나타내고 희석제 중에서 HDGE의 경우가 가장 좋은 접착력을 나타내었고 희식제의 양이 증가할수록 접착력은 증가하였다. 실리카와 철분을 섞어 반고체형 에폭시 접착제를 제조한 경우 기존의 제품보다 우수한 접착력을 나타내었다. 따라서 본 연구에서 개발한 반고체형 접착제는 제조공정 코스트 등에 대한 검토와 함께 제품화하여 토목, 건축 분야의 콘크리트 균열 접착, 볼트와 콘크리트의 접합, 목재의 접합 등에 간편하게 사용될 수 있으며, 배합물질과 비율에 따라 전기전자. 토목건축, 자동차산업 등의 산업용 접착제로서 응용될 수 있을 것으로 기대된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.445-448
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• 2008

The unsaturated polyester(UP) and epoxy resin have a superior material properties and a chemical resistance using sewerage pipes rehabilitation. However, UP and epoxy have not a low temperatures harding, the requirement $8{\sim}11$ hours long times harding and heating system used by reinforcement liner. This study is to evaluate the effects of low temperature harding properties methyl methacrylate(MMA) monomer using expanded polystyrene(EPS) and UP in addition of initiator and promoters. From the test result, viscosity tends to increase with increasing EPS and UP contents. However, harding time change of the MMA resins which it follows in addition of the initiator and promoter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3822-3826
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• 2012

We have studied the effect of temperature and exposure time on the UV curing rate of Urethane Acrylate. UV dose has been modulated by changing the electric power, and temperature has been controled by coating rate and water temperature of the coating roll. Curing rate was evaluated by measuring gel fraction of the cured film. It has been found that effect of coating velocity on the gel fraction of the final film is predominant, but role of temperature of the UV chamber is negligible. These observations imply that exposure time of UV light is critical to have a fully cured film. To better understand the effect of design and operating condition of UV coater on the behavior of UV curing of Urethane Acrylate, we have also conducted heat-flux analysis of UV chamber.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.51-56
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• 2014

After the preparation of low-cost conductive paste containing Ag-coated Cu flakes, thermal conductivity and electrical resistivity of the paste were measured with different curing conditions. Under air-curing conditions, the thermal conductivity of the cured sample increased with an increase of curing time from 30 to 60 min. After identical curing time of 60 min, the sample cured under nitrogen indicated more enhanced thermal conductivity than that cured under air, approaching that of paste containing pure Ag flakes. Under air-curing conditions, meanwhile, the electrical resistivity of the cured sample increased with an increase of curing time from 30 to 60 min. After identical curing time of 60 min, however, the sample cured under nitrogen indicated extremely enhanced electrical resistivity ($7.59{\times}10^{-5}{\Omega}{\cdot}cm$) in comparison with that cured under air.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.929-932
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• 2008

The unsaturated polyester(UP) and epoxy resin have a superior material properties and a chemical resistance using sewerage pipes rehabilitation. However, UP and epoxy have not a low temperatures harding, the requirement $8{\sim}11$ hours long times harding and heating system used by reinforcement liner. This study is to evaluate the effects of low temperature harding properties methyl methacrylate(MMA) monomer using expanded polystyrene(EPS) in addition of initiator and promoters. From the test result, viscosity tends to increase with increasing EPS contents. However, harding time change of the MMA resins which it follows in addition of the initiator and promoter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.295-302
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• 2011

The setting time which is the important element for the determination of slip-up speed of Slip-Form system is the hardening time of early-age concrete when the in place concrete has minimum compressive strength before the concrete appears out of Slip-Form system. But it is very difficult to predict the setting time because it depends on not only the composition ratio of concrete but also various conditions of construction fields. Thus, the technique to estimate accurately and continuously the hardening time of early-age in place concrete during operating Slip-Form system is necessary to guarantee the safety of Slip-Form system and the maintenance of the shape of concrete. Ultrasonic wave-based nondestructive testing methods have the advantages which are accurate and continuous in estimating concrete compressive strength. Of such methods, the method using surface wave which propagates along the surface of material is effective for thick member such as a pylon. Thus, in this paper a study on the determination of slip-up speed for Slip-Form system using surface wave velocity is performed. The relation between the slip-up speed of Slip-Form system and the setting time is formulated, and the surface wave velocity is estimated from continuous wavelet transform of the numerical results for surface wave propagation. Finally, the accuracy of this method according to the distance between the wave source and receivers and the relation between the estimated surface wave velocity and the elastic modulus are investigated.