• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.160-161
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• 2013

Recently, the enviroment problem is serious due to the global warming phenomenon because of the greenhouse gas exhaustion. In addition, the effort to reduce the problem in the situation where the severity of the destruction of environment because of the indiscriminate picking of the that is the raw material of the cement, Accordingly, in the interior of a country, the industrial site using the artificial stone instead of the natural stone is increased. Thus the cement reduction amount of use and substitute material research is the urgent actual condition with the gas emission, which here it is generated in conducting compression molding in the building stone manufacturing process performance degradation phenomenon and fire resistance, and problem of the durability. limestone and aggregate and exhaustion of resource are emphasized is continued. In this research, the fly ash and waste porcelain is applied to the magnesia phosphate composite (MPC) and the characteristic of the artificial stone according to it tries to be looked into.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.41-46
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• 2010

This is to show some basic data for introducing both circulated aggregate and recycled powder producing waste concrete. Standard-mixing design for 24MPa has been basically used and added and replaced normal aggregate with recycled powder made of waste concrete. In addition, polycarboxylate high-range water reducing agent has been used because recycled powder is missing adhesive strength and it is not compare with cement's adhesive strength. Compressive strength with powder mixture of 2%, 4%, 6%, 8%, and 10% has been decreased down to 80% of normal concrete material strength without recycled powder mixture. This result has same decreasing proportion to tensile strength of the material. Resistant capacity change of beam varying with recycled powder mixture has been decreased down to 60% of normal concrete bean capacity, while there are 80% decrease of material strength. But strength and capacity change has same consistent decrease ratio. It is found that recycled powder with approximately 15% unit concrete volume can be replaced with cement in reasonable admixture mixing condition.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.436-442
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• 2002

Recently color AC PDP(plasma display panel) technology is rapidly improved. However, the luminous efficiency improvement is a key issue for making plasma display into a large-area flat display. In this paper, we suggest a new concentration of Xe in He-Ne-Xe gas mixture in order to achieve a high luminous efficiency of color AC PDPs. We calculated the densities of 25 species as a function of the time zero dimensional simulation using CVODE solver and we compared the results of zero dimensional simulation with a measurement of photo wave brightness and luminous efficiency, in order to find the optimum mixing condition of He-Ne-Xe gas in color plasma display panel. We obtained a high discharge speed under Xe mixing ratio of 1% by simulation and confirmed that through measuring photo wave.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.188-192
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• 2000

In this study PZT etching was performed using planar inductively coupled Ar/Cl$_2$/BCI$_3$ plasma. The etch rate of PZT film was 2450 $\AA$/min at Ar(20)/BCl$_3$(80) gas mixing ratio and substrate temperature of 8$0^{\circ}C$. X-ray photoelectron spectroscopy(XPS) analysis for films composition of etched PZT surface was utilized. The chemical bond of PbO is broken by ion bombardment and Cl radical, and the peak of metal Pb in a Pb 4f narrow scan begins to appear upon etching. As increasing additive BCl$_3$content the relative content of oxygen decreases rapidly in contrast with etch rate of PZT thin film. So we though that the etch rate of PZT thin film increased because abundant B and BCl radicals made volatile oxy-compound such as B$_{x}$/O$_{y}$ and/or BClO$_{x}$ bond. We achieved etch profile of about 80$^{\circ}$ at Ar(20)/BCl$_3$(80) gas mixing condition and substrate temperature of 8$0^{\circ}C$TEX>X>.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.787-794
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• 2010

This paper aims to evaluate the effect of each material ingredient on mechanical and dynamic performance and to determine an optimal mixing condition of a rubber granule layer. To minimize the required number of tests, the test matrix was established by using the design of experiments (DOE). The tensile tests were then performed to identify the mechanical properties. Also, to evaluate the dynamic performance that the IAAF has required for athletics tracks for athletes' safety and balance, a series of impact tests were performed by using the so-called the "artificial athlete" machine. Finally, the response surface methodology was used to decide the optimal mixing conditions needed to achieve a high level of mechanical properties and dynamic performance.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.7-14
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• 2010

This study investigated the effect on reducing the pressure rise rate(PRR) in HCCI Engine by the variation of mixing ratio in the pre-mixture of DME and n-Butane that has different auto-ignition characteristics. In addition to measure of gas pressure in the engine cylinder, chemiluminescence image using the optical accessible engine and numerical analysis with multi-zones model were used to assess the combustion at each local area in the combustion chamber. The maximum PRR changes depending on mixing condition of DME and n-Butane. When DME is stratified and n-Butane is distributed uniformly, maximum PRR becomes lowest which is about 0.25MPa/ms and it corresponds to 5deg. retarding of CA50.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.693-696
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• 2004

For InGaP/GaAs HBT applications, we have developed characterized MIM capacitors with thin $1000{\AA}$ PECVD silicon nitride which were deposited with $SiH_4/NH_3$ gas mixing rate, working pressure, and RF power of PECVD at $300^{\circ}C$ and had the capacitance density of 600 pF/$mm^2$ with the breakdown electric fields of 3073 MV/cm. Three PECVD process parameters were designed to lower the refractive index and then lower the deposition rate of silicon nitride films for the high breakdown electric field. At the PECVD process condition of gas mixing rate (0.92), working pressure (1.3 Torr), RF power (53 W), the AFM Rms value of about $1000{\AA}$ silicon nitride on the bottom metal was the lowest of 0.662 nmand breakdown electric fields were the highest of about 73 MV/cm.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3625-3634
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• 2021

The crossflow is the key phenomenon in turbulent flow inside rod bundles. In order to establish confidence on application of computational fluid dynamics (CFD) to simulate the crossflow in rod bundles, three Reynolds-Averaged Navier Stokes (RANS) models i.e. the realizable k-ε model, the k-ω SST model and the Reynolds stress model (RSM), and the Large Eddy simulations (LES) with the Wall-Adapting Local Eddy-viscosity (WALE) model are validated based on the Particle Image Velocimetry (PIV) flow measurement experiment in a 5 × 5 rod bundle. In order to investigate effects of periodic boundary condition in the gap, the numerical results obtained with four inner subchannels are compared with that obtained with the whole 5 × 5 rod bundle. The results show that periodic boundaries in the gaps produce strong errors far downstream of the spacer grid, and therefore the full 5 × 5 rod bundle should be simulated. Furthermore, it can be concluded, that the realizable k-ε model can only provide reasonable results very close to the spacer grid, while the other investigated models are in good agreement with the experimental data in the whole downstream flow in the rod bundle. The LES approach shows superiority to the RANS models.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.10-11
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• 2020

This research is part of the research for unifying the mass concrete and utilizing the rate of super retarding agent. We analyzed the performance of super retarding agent under low temperature conditions. It was found that there was no deterioration in fluidity and air quality due to the change in the super retarding agent mixing rate. It was found that when super retarding agent was mixed up to 0.5 %, it was delayed for 22.3 hours at 20℃, 48.2 hours at 10℃, and 48.5 hours at 5℃. Therefore in order to ensure the performance required at the site, the super retarding agent mixing rate must be determined by fully considering the situation at the site. In addition it will be analyzed that super retarding agent performance analysis at high temperature will be required in subsequent studies.

• Journal of Aquaculture
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• v.7 no.4
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• pp.239-249
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• 1994

This study was conducted to elucidate mixing characteristics of the media to dertermine hydraulic model parameters of the three phase fluidized bed for the water quality management of aquaculture. The volume and H/D ratio of the reactor were 1.76 Liter and 10.9, respectively. The experimental results showed that variance $(\sigma^2)$ and dispersion number $(D/{\mu}L)$ were above 0.47 and $0.35\~\infty$, respectively. Therefore, the condition of the reactor was almost ideal complete mixing. The dependence of the overall oxygen-transfer coefficient $(K_{La})$ on each experimental variables through a multple linear regression was given by the following equation ; $$K_{La}\;=\;44.9(D_i/D_c)^{-0.4611}\;A_f^{0.8622}\;C_m^{-0.0746}\;d_p^{-0.4302}$$