• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.132-138
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• 2003

The effect of synthesis condition, type of starting materials, mole ratio, mixing. aging, and crystallization temperature and time, on the size of FAU-type zeolite has been studied. Different mixing route may lead to the different phase of zeolite even with the same starting materials. In general, the size of particles is smaller after aging, especially at lower aging temperature. Two step mixture gel preparation method resulted to not only the reduction of crystallization time but also that of particle size, but without the aging of two mixture gels before the preparation of the overall gel in the second step, only the crystallization time was reduced, not the particle size. The FAU-type zeolite with average particle size 0.4$\mu$m and BET surface area 838 $m^2$/g was obtained from starting materials of liquid sodium silicate, sodium aluminate, and sodium hydroxide with two step preparation of mixture gel, aging of the mixture gels in two steps, which effectively reduced the crystallization time and particle size.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1155-1163
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• 2016

This paper deals with an estimation procedure of variance components in a mixed effects model by projections. Projections are used to obtain sums of squares instead of using reductions in sums of squares due to fitting both the assumed model and sub-models in the fitting constants method. A projection matrix can be obtained for the residual model at each step by a stepwise procedure to test the hypotheses. A weighted least squares method is used for the estimation of fixed effects. Satterthwaite's approximation is done for the confidence intervals for variance components.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.460-466
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• 2009

The mixing method of water and chemicals is significant in a small-scale water supply system because drinking water should be supplied with a certain quantity of remaining chemicals maintained. In the present study, the concentration distribution and the mixing index were obtained from four models, which were to find out the optimal mixing method of water and chemicals. The two models brought the good mixing effects out of the four, one for providing chemicals from the center of water supply pipe and the other for setting up the semicircle block at the downstream of the chemicals-providing pipe. As a result, the mixing effect was found out to be increased due to the diffusion and the disturbance of flows. In conclusion, these numerical results are expected to contribute to designing the optimal mixing system.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.453-456
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• 2007

노인 복지 환경에서 혼합주도 협력(mixed-initiative collaboration)이 가능한 로봇의 지능 개발이 본 연구의 궁극적인 목표이다. 본 논문에서는 다양한 담화(discourse)으로부터 협력 과정들을 분석하여 상호 주도 협력을 위한 이슈들을 찾아내고, 이러한 주요 요소를 바탕으로 상대 인지시스템의 사용자 모델(user model)을 포함할 수 있는 상호 스크립트 모형(joint script model)을 제안하고 이를 이용한 로봇 계획법(robot planning)의 방법론과 실험에 대한 접근법을 제시한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.05a
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• pp.109-117
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• 1996

Strand Burner 내에 설치되는 추진제에 10$\mu\textrm{m}$굵기의 Thermocouple을 설치하여 각 압력하에서의 연소속도 및 연소시의 Thermal Structure의 정보를 얻는 방법과 러시아의I.C.P에서 공동실험을 통하여 얻은 60%의 니트로글리세린과 40%의 니트로셀룰로오스를 혼합한 더블베이스 추진제 및 AP와 에폭시수지를 혼합한 간이 Composite형 추진제의 Thermal Structure를 조사한다.

• The Korean Journal of Applied Statistics
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• v.15 no.2
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• pp.337-354
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• 2002

This paper derives three estimation methods for the between group variance component for serially correlated random model. To compare their estimation capability, three designs having different degree of unbalancedness are considered. The so-called empirical quantile dispersion graphs(EQDGs) used to compare estimation methods as well as designs. The proposed conditional ANOVA estimation is robust for design unbalancedness, however, ML estimation is preferred to the conditional AOVA and REML estimation regardless of design unbalancedness and correlation coefficient.

• Journal of the Korean Institute of Gas
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• v.9 no.4 s.29
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• pp.50-56
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• 2005

Liquefied Petroleum 6aso-PG) is combustible gas which used for fuel for domestic and automobiles. A research for adjust a component of LPG to improve the fuel characteristics and control the manufacturing process of that is carrying in petrochemical industry. Some kinds of LPG blending is considered as a adjusting method to control component of LPG. LPG is mainly propane for domestic use and butane for automobile use but propylene and butylene also a kind of LPG Change of explosion characteristic and combustion gas component by mixing of propylene in propane and butane was measured and analysed in this research. Based on the result of experiment, it was found that explosion pressure and pressure rise rate was slightly increased with mixing rate of propylene and it was considered the possibility of increasing the CO concentration in combustion gas with increase the mixing rate of propylene.

• Polymer(Korea)
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• v.26 no.6
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• pp.812-820
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• 2002

The positive temperature coefficient (PTC) characteristics of polymer composites were investigated with the nano-sized carbon black particles using solution tasting and melt compounding methods. The polymeric PTC composites should the electrical threshold at 35 wt% for the melt compounding method and 40 wt% for the solution casting method. The ethylene vinylacetate copolymer (EVA) composite showed a gradual increase of resistance as a function of temperature and showed a maximum at the polymer molting point. The resistance of the high-density polythylene (HDPE) composite remains unchanged with temperature but started to Increase sharply near the melting point of HDPE and showed a maximum resistance at the melting point of HDPE. The dispersion of nano-sized carbon black particles was investigated by scanning electron microscopy (SEM) and low resistance after electrical threshold, and both methods exhibited a well dispersed morphology. When the electric current was applied to the PTC composites, the resistance started increasing at the curie temperature and further increased until the trip temperature was roached. Then the resistance remained stable over the trip temperature. The secondary increase started at T$\sub$m/ of matrix polymer and kept increasing up to the trip temperature.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.225-232
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• 2003

With an aim placed on its exploitation on practical injector design, liquid phase mixing due to unlike split triplet impinging element is experimentally investigated by a series of cold tests. Non-reacting kerosene/water spray simulates the kerosene/LOX propellant combination. Measurements of local mixture ratio distribution were made for different injection configurations and different momentum ratios. Mixing and mixing controlled characteristic velocity efficiencies are measured in terms of oxidizer/fuel jet momentum ratio from 0.5 to 8. Extent of mixing and its influence on hot performance are estimated in terms of mixing efficiency and mixing controlled characteristic velocity. Envelope of design locus for optimum mixing quality and corresponding maximum hot performance are proposed. Effects of momentum ratio, orifice diameter ratio and jet velocity ratios are also presented and discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4C
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• pp.139-147
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• 2012

In this study, various laboratory tests using bottom ash, which has similar engineering properties with sand, were conducted in order to solve the problem of clogging in granular compaction pile and to address sand supply and demand. In particular, testing was performed to help reduce clogging and minimize voids in a crushed stone compaction pile constructed in soft ground. Based on compaction tests and large diameter direct shear tests, an optimum mixing ratio was determined to be 80:20 (crushed stone to bottom ash) because an 80:20 mixing ratio showed the highest shear strength. Test results showed that as the bottom ash content increased above 20%, internal friction angle decreased. Another test method showed freezing and thawing had little effect when the replacement ratio was over 40%. Therefore, bottom ash mixed compaction piles in soft ground are most economical at a 40% replacement ratio.