• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.183-186
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• 1991

In order to prepare the functional organic optic meterials, the capacitive coupled gas flow type plasma polymerization apparatus was designed and manufactured. Styrene and para-Xylene monomer were adopt as organic materisl. Optical constant, refrative index, extinction coefficient of organic thin films by the gas flow type plasma polymerization appratus were determined by envelope method using spectrophotometry. The refractive index of plasma polymerized thin films was decreased in accordance to increase of wave length and discharge time. The extinction coefficient was very small compared with refractive index. From the experimental result of optical constant and film thickness, it was considered that the films which had required optical properties and thickness can be prepared by control of polymerization condition.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.14-17
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• 1995

This study is designed for producing and analyzing the structure application properties of the ready mixed concrete of specified concrete strength about 400kg/$\textrm{cm}^2$ in the batcher plant. And this part is designed for analyzing to the slump, slump flow, air content and unit weight in fresh state. By the test results of fresh concrete state, the slump, slump flow and air content are decreased, but unit weight is increased while open time is passed.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.200-203
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• 2004

In this study, it is examined the properties of flow and early strength of concrete according to superplasticizer. For this experiment, it is analyzed that the flow and strength properties according to the mixture factors, compared with naphthalene superplasticizer(normal & delay type) focused on polycarboxylate superplasticizer. (1) The slump loss of concrete used polycarboxylate superplasticizer showed $4\~8cm$, it is judged that slump loss according to the time lapse can be minimized. (2) The performance of polycarboxylate superplasticizer is about $70\%$ level of the normal naphthalene type, it is superior to the delay type, but the performance showed so lowly. The 28days, early strength didn't differ according to the kind of superplasticizer.

• Journal of computational fluids engineering
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• v.6 no.4
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• pp.8-14
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• 2001

The phenomena of two-phase suspension flows appear widely in nature and industrial processes. Hence, it is of great importance to understand the mechanism of the gas-solid two-phase flows. In the present study, the numerical simulation has been approached by utilizing the Eulerian-Lagrangian methodology for describing the characteristics of the fluid and particulate phases in a vertical pipe and a 90°square-sectioned bend. The continuous phase(gas phase) is described by the Eulerian formulation and a κ-ε turbulence model is employed to find mean and turbulent properties of the gas phase. The particle properties(velocity and trajectory) are then described by a Lagrangian approach and computed using the mean velocity and turbulent fluctuating velocity of the gas phase. The predictions are compared with measurements by laser-Doppler velocimeter for the validation. As a result, the calculated results show good agreements.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1756-1766
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• 2003

Numerical modeling is carried out to investigate forced convective heat transfer to near-critical water in developing laminar flow through a circular tube. Due to large variations of thermo-physical properties such as density, specific heat, viscosity, and thermal conductivity near thermodynamic critical point, heat transfer characteristics show quite different behavior compared with pure forced convection. With flow acceleration along the tube unusual behavior of heat transfer coefficient and friction factor occurs when the fluid enthalpy passes through pseudocritical point of pressure in the tube. There is also a transition behavior from liquid-like phase to gas-like phase in the developing region. Numerical results with constant heat flux boundary conditions are obtained for reduced pressures from 1.09 to 1.99. Graphical results for velocity, temperature, and heat transfer coefficient with Stanton number are presented and analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.368-372
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• 2005

The variation of regression rate of single port hybrid rocket was studied with various fuel. As fuel, PE, PMMA were used and gas oxygen as oxidizer. The regression rate depends on but flow rates of oxidizer also thermodynamic properties of fuel. In this study, the empirical relation for regression rate of solid fuel were found with mass transfer coefficient(B number) and oxidizer flow rate.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.605-608
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• 2006

The purpose of this research is to develop the fireproofing mortar through the improved fireproofing properties. Therefore, after manufactured the mortor by changing the mixture rate of the perlite(PL) in three level, we investigated air content, flow value and compressive strength. As a result of this research, as the mixture rate was increased and the air content was also increased. But the flow ability and the compressive strength of the mortar were comparably decreased. Beside, we also found that there is efficiency of the lightweight by mixed PL.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.711-714
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• 2005

This paper focused on development of geopolymer for wood wool ceramic board. Geopolymer can substitude ordinary portland cement and its accelerator of wood wool cement board as inorganic polymer. In this study, what we would obtain geopolymer's properties such as initial setting time(KS L 5108), flow(KS L 5102) and compressive strength of 3days aged(KS L 5105), was less than 1 hour, more than $110\%$, more than 40Mpa. Geopolymer have three essential materials called filler, hardener and geopolymer liquor. So, We applied filler by quartz, hardener by blast furnace slag powder, metakaoline and fly ash, geopolymer liquor by NaOH, KOH and sodium silicate solution. As result of this experiment, what we could obtain best fitted geopolymer's properties such as initial setting time, flow and compressive strength of 3days aged, was 45min, $116\%$ and 43.6Mpa. This result can be applicable to commercial wood wool ceramic board.

• Journal of the Korea Institute of Building Construction
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• v.12 no.3
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• pp.332-339
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• 2012

In this study, six mortar mixes were tested in order to examine the significance and limitations of hydrophilic fiber in terms of its capacity to enhance the tensile resistance of Hwangtoh mortar. Lyocell, polyamide and polyvinyl alcohol (PVA) fibers were selected for the main test parameters. The tensile capacity of mortars tested was evaluated based on the splitting tensile strength and the modulus of fracture, while their ductility was examined using the toughness indices specified in ASTM. Test results showed that the addition of lyocell and PVA fibers had little influence on the flow of the Hwangtoh mortars. To enhance the tensile capacity and toughness index of Hwangtoh mortar, it is proposed that fiber spacing above 0.0003 is required, regardless of the type of fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.413-416
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• 2003

Experimental tests on the high strength self-compacting concrete with light-weight fine aggregate and light-weight coarse aggregate(LHSSC) were performed with slump-flow, reaching time to the slump-flow of 500mm, V-funnel dropping time and U-box difference level and compressive strength. LHSCC with light-weight fine aggregate of 75% and light-weight coarse aggregate of 100% was only satisfied with the property conditions of second self-compacting concrete(SCC), like as flowability, resistance to segregation and filling ability. The 28-day compressive strength of LHSCC indicated above 300kgf/$\textrm{cm}^2$ in all concrete mixtures, and it was increased to increase the replacement ratio of light-weight fine aggregate or to decrease the replacement ratio of light-weight coarse aggregate. Therefore, for satisfying the properties of fresh SCC and hardened concrete with above 350kgf/$\textrm{cm}^2$, it would expected that the replacement ratio of light-weight fine aggregate and light-weight coarse aggregate will be determined with 50~75% and 25~50%, respectively.