• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1649-1657
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• 2010

We have investigated the unexpected phenomena on the surface of molded GFRP composites. The major cause of the unevenness, as a result of which the surface becomes rough, is a shrinking of the matrix in the process of holding pressure and cooling temperature. The higher holding pressure load in a molding process and the lower demolding temperature in an annealing experiment, the better GFRP composites moldings improved its appearance. In addition, by taking the holding pressure and demolding temperature into consideration, we evaluate the process that causes the surface unevenness and the variation in the fiber projection height.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.91-96
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• 2016

In this study, effects of demolding temperature (DT) on the formability and optical properties were evaluated in order to optimize thermal nanoimprint lithography for anti-reflective film. Characterization on optical property showed that optical performance was gradually enhanced as the DT increased up to $70^{\circ}C$ while the transmittance and the reflectance was degraded as the DT increased further to $100^{\circ}C$. In addition, similar behavior was observed from formability analysis. It was contributed to the formation of free volume and viscose flow. Therefore, it was concluded that the formability and optical property are highly influenced by the formation of free volume and viscous flow of polymer depending on the DT.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.117-121
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• 2008

This study investigates practical application of high early strength type concrete using fine particle classifying cement, and the results are summarized as following. The replacement use of FC 30% did not great influence on concrete mix, therefore mixing without additional SP and AE was available using equal mix with OPC. The ratio of increasing temperature by heat of hydration was similar with OPC, and the compressive strength was over then 5MPa at -28℃ outside temperature on 2nd day. Therefore, it is considering that the first purpose, the effect of shortening terms of work by early demolding, will be available. The rebound rate of type "P" schumidt hammer was relative with compressive strength, and the rebound rate for verifying 5MPa of compressive strength was estimated about 55 considering rate of safety. Therefore, assuming demolding date is available efficiently.

• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.68-74
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• 2017

Nanoimprint lithography (NIL) is a next generation technology for fabrication of micrometer and nanometer scale patterns. There have been considerable attentions on NIL due to its potential abilities that enable cost-effective and high-throughput nanofabrication to the display device and semiconductor industry. Up to now there have been a lot of researches on thermal NIL, but most of them have been focused on polymer deformation in the molding process and there are very few studies on the cooling and demolding process. In this paper a cooling process of the polymer resist in thermal NIL is analyzed with finite element method. The modeling of cooling process for mold, polymer resist and substrate is developed. And the cooling process is numerically investigated with the effects of imprinting temperature and residual layer thickness of polymer resist on stress distribution of the polymer resist. The results show that the lower imprinting temperature, the higher the maximum von Mises stress and that the thicker the residual layer, the greater maximum von Mises stress.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.305-310
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• 2004

The Hot Embossing Lithography(HEL) as a method for the fabrication of nanostructure with polymer is becoming increasingly important because of its simple process, low cost, high replication fidelity and relatively high throughput. In this study, we investigated the characteristics of hot embossing lithography as a nanoreplication technique. To grasp characteristics of nano patterning rheology by process parameters(embossing temperature, pressure and time), we have carried out various experiments by using the DVD(400nm pattern width) and Blu-ray nickel stamps(150nm pattern width). During the hot embossing process, we have observed the characteristics of the size effect. The quality of products made by hot embossing is affected by its cooling shrinkage. The demolding process at the glass transition temperature results in low quality because of the shrinkage of the polymer. Therefore, the quantification of the temperature condition is essential for the replication of high quality.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.1-5
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• 2015

Recently, data throughput of smart electric devices increases dramatically. There is a great interest in a new technology which exceeds the limit of electrical transmission method. Optical PCB can supplement the weakness of electrical signal processing, the research for optical PCB is very active. In this paper, we propose the thermal imprint lithography process to fabrication optical layer of optical PCB and experiment to optimize the process conditions. We confirm process time, pressure, process temperature, demolding temperature and fabricate optical interconnection structure which has $45^{\circ}$ tilted mirror surface for confirm the interconnection efficiency.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.755-760
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• 1998

In the present, we have developed high strength concrete for the sleepers of high speed rail and verified its applicability by in-situ applications. Concrete for sleepers is manufactured by steam curing at low temperature(below 55$^{\circ}C$), and should be finished its manufacturing process such as placing, curing, demolding and prestressing in 24 hours. The sleepers need its compressive strength above 350kg/$\textrm{cm}^2$ in 15 hours, air-entrainment for durability and nominal design strength of 600kg/$\textrm{cm}^2$, considering its quality variation at factory. We performed the optimum mix design of concrete and verified the rightness of the use of TYPE III cement. Finally, we have confirmed the manufactured sleepers satisfy the required material properties through in-situ application.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.152-153
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• 2017

In the construction site, it is necessary to estimate the compressive strength of concrete in order to adjust the demolding time of the form, and establish and adjust the construction schedule. The compressive strength of concrete is determined by various influencing factors. However, the conventional method for estimating the compressive strength of concrete has been suggested by considering only 1 to 3 specific influential factors as variables. In this study, six influential factors (Water, Cement, Fly ash, Blast furnace slag, Curing temperature, and humidity) of papers opened for 10 years were collected at three conferences in order to know the various correlations among data and the tendency of data. After using algorithm of various methods of machine learning techniques, we selected the most suitable regression analysis model for estimating the compressive strength.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.284-289
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• 2004

Since polymer materials at elevated temperatures are usually rate-sensitive, the analysis of RTP process requires considering the effect of the rate-dependent. The material behavior that exhibits rate-sensitivity is called visco-plastic. A two-dimensional visco-plastic finite element formulation which constitutive equation is based on the formulation proposed by Perzyna is presented. This Paper is purposed to calcuate pressure distribution on PMMA in compression process and to predict the relationship with defects after demolding process. This paper analyzes, both analytically and numerically, the pressure distributions on the surface of PMMA during open-die RTP process. In this research, PMMA is used to be simulated at $110^{\circ}C$ near the transition temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.83-84
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• 2017

In the construction site, it is necessary to estimate the compressive strength of concrete in order to adjust the demolding time of the form, and establish and adjust the construction schedule. The compressive strength of concrete is determined by various influencing factors. However, the conventional method for estimating the compressive strength of concrete has been suggested by considering only 1 to 3 specific influential factors as variables. In this study, seven influential factors (W/B ratio, Water, Cement, Fly ash, Blast furnace slag, Curing temperature, and humidity) of papers opened for 10 years were collected at three conferences in order to know the various correlations among data and the tendency of data. The purpose of this paper is to estimate compressive strength more accurately by applying it to algorithm of the Deep learning.