• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.82-82
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• 2014

마감 도장이 완료된 면이 장기간 노출된 상태에서 후속 작업으로 인해 금속 분진 등의 오염물이 쌓이면 수분 및 염분 등과의 반응으로 도장 표면에 녹 등의 2차 오염이 발생하여 광택이나 표면 미려함 등을 잃어버리게 된다. 이럴 경우 소요되는 시간과 경비를 줄이기 위해 재도장 작업 대신 도장 표면의 오염 막을 제거하기 위한 방법으로 rust remover가 사용되고 있으나, 현재 rust remover 사용에 따른 도막 열화에 관한 객관적인 자료가 없는 실정이다. 본 연구에서는 당에서 사용되고 있는 선박용 마감 도료를 대상으로 rust remover가 도막 표면 열화에 미치는 영향에 대하여 조사 검토하다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.30-35
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• 2000

A floating solidification technique is a process applied extensively to the production of glass plates. We used the technique for fabrication of Si plate. We used the proper liquid substrate material of 50 wt% $SiO_2$- 21 wt% $A1_2$$O_3$-29 wt% MnO, after studying ternary phase diagram of various oxides systems. The liquid substrate material has proper properties in the aspects of temperature, density and reactivity. But results showed some problems in fluidity and surface tension of the liquid substrate material.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.04a
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• pp.13-13
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• 1999

본 논문에서는 해석영역의 형상변화, 즉 로켓노즐 내열재의 삭마로 인해 야기된 경계 면의 이동을 고려하면서 2차원 비정상 비등방성 재료의 열전달 문제를 해석할 수 있는 수치해석에 대해 기술하였다. 수치해석 알고리즘은 유한요소법이며 열해석시 경계면 이동으로 인한 격자계의 절점 좌표점이 계산과정 동안에 이동하는 변형 가능한 유한요소격자(transformable finite-element grid)를 사용하였다. 본 수치해석기법의 타당성 입증을 위해 극심한 열하중이 부여된 조건하에서 엄밀해가 존재하는 비정상 축대칭문제 및 고체로켓 노즐내열재에 대해 열해석을 수행하였으며, 그 결과 수치해는 엄밀해 또는 실험치와 잘 일치함을 보이었다. 여러 가지 복합재로 구성된 내삽노즐 또는 외삽노즐에 대해서도 안정된 수치해를 얻을 수 있었다. 아울러 노즐목삽입재로 탄소-탄소 복합재를 적용한 고체추진기관 내삽노즐을 해석모델로 택하여 열전달 해석을 수행하고 해석결과를 분석하였다. 노즐의 표면산화반응에 대한 열반응상수, 즉 Arrhenius 형태로 표시된 식에서 pre-exponential factor 및 activation energy 변화가 탄소-탄소 복합재 및 탄소-페놀릭 복합재의 삭마량에 미치는 영향에 대해서 고찰하였다.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.471-476
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• 2008

The thermal and mechanical properties and morphology of epoxy/polyamide/DDS/2E4MZ-CNS reactive blends with various amounts of polyamide were investigated. The amount of polyamide was 10, 20, and 30 phr and 2 phr of catalyst was added to the blend to cure at $180^{\circ}C$ for 30 min. By adding the catalyst, 2E4MZ-CNS, to the blend, the cure reaction occurred at a lower temperature. From the SEM images, it was found that the boundary of separated-phase was unclear and the phase was co-continuous. Without the catalyst, however, the boundary of separated-phase was clear. The control of cure temperature and morphology could be achieved by using a proper catalyst and consequently the mechanical strength increased by 20% compared to the blend without the catalyst due to the strong interaction between epoxy matrix and phase-separated polyamide at the interface.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.425-430
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• 2012

In this study, a preconverter of an MCFC for an emergency electric power supplier is numerically simulated to increase the hydrogen production from natural gas (methane). A commercial code is used to simulate a porous catalyst with a user subroutine to model three dominant chemical reactions-steam reforming, water-gas shift, and direct steam reforming. To achieve a fuel conversion rate of 10% in the preconverter, the required external heat flux is supplied from the outer wall of the preconverter. The calculated results show that the temperature distribution and chemical reaction are extremely nonuniform near the wall of the preconverter. These phenomena can be explained by the low heat conductivity of the porous catalyst and the endothermic reforming reaction. The calculated results indicate that the use of a compact-size preconverter makes the chemical reaction more uniform and provides many advantages for catalyst maintenance.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.4
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• pp.336-346
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• 1994

We studied the reaction between silicon and carbon. Silicon granules and silicon with 0.2 wt% carbon powders were prepared for sample and then they were heated up to the $1450^{\circ}C, 1550^{\circ}C, 1650^{\circ}C, 1700^{\circ}C$ and were dwelled 1 hr and 4 hrs, respectively. we studied the change of morphologies of molten silicon and the formation of SiC following the reaction withcarbon using optical microscope, SEM, and XRD. Above the melting point of silicon, oxygens are precipitated during the decomposition of quartz used crucible. SiO formed from the reaction between molten silicon and precipitated oxygen evaporated and made the surface defects. SiC were formed with the reaction between the unreacted carbon and molten silicon. Polytype of the SiC formed at the solidification interface was ${\alpha}-SiC$.

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.24-34
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• 1992

Recent studies dealing with the fundamental understanding and applications of bimetallic catalysts are discussed. Bimetallic catalysts have had a major industrial impact, specifically for the reforming of petroleum naphtha, for the hydrogen reduction of carbon monoxide, and for the three way catalytic converter system. The action of the bimetallic catalysts in these reactions may be interpreted in terms of ensembles, electronic influences and surface structure. Various combinations of metal pairs have been considered in order to evaluate the role played by the added metals. For catalyst selectivity control, the possibility of surface enrichment of one element has been recognised. More generally, the influence of preparative variables on the formation of supported catalysts has been clarified, In particular by temperature programmed reduction (TPR). Information on the structure of bimetallic catalysts has been obtained with chemical probes, such as chemisorption and reaction rate measurement and physical probes, such as extended X-ray absorption fine structure (EXAFS), scanning transmission electron microscopy (STEM) and Xe-NMR.

• Journal of the Korean Chemical Society
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• v.28 no.6
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• pp.366-373
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• 1984

Methanolysis rates of benzylbenzenesulfonates, substituted both on the substrate (Y) and on the leaving group (Z), were determined in MeOH-MeCN mixtures. The results showed that the reaction proceeds via the dissociative $S_N2$ mechanism, in which bond breaking proceeds in greater degree compared to bond formation at the transition state(TS). Multiple Hammett correlation analysis showed that the cross term, ${\rho}_{YZ}$, is very small and hence the cross interaction of two substituents, Y and Z, at the TS is not important, supporting the dissociative $S_N2 $ type mechanism. While transition state variations predicted by the quantum mechanical model is shown to agree in general with the experimental results, those predicted by the potential energy surface model failed to account for the leaving group effect properly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.663-668
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• 2017

Dye waste water generated in the dye industry is categorized as hazardous waste water that requires appropriate treatment. The pilot scale experimental trials were carried out using dye waste water as an effective additive for the selective non-catalytic reduction (SNCR) of NOx in combustion flue gases. The additives were waste liquor obtained from the dye industry and several purification steps were taken to make a standardized reagents. The dye waste water was shown to possess valuable SNCR qualities (at least 87% NOx reduction efficiency) considering its availability as a waste product, which has to be strictly treated, and have little effects on CO removal. The results indicated that the NO removal efficiency increased first and then decreased with increasing temperature within $750-1150^{\circ}C$. The maximum NO reduction efficiency was approximately 87% at the optimal reaction temperature. A more than 10% increase in NO reduction was achieved in the presence of 1000 ppm Na-additives (dye waste water) compared to that without additives. The Na-based additives have also a significant promoting effect on $N_2O$ reduction and within the SNCR temperature window.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.702-708
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• 2018

Hydrogels are natural polymer networks that can contain huge quantities of water and many cosmetical ingredients. Their hydrophilic functional groups creates a matrix, which allows high efficacy in delivering active ingredients into the skin. In industry, hydrating properties and strength of the hydrogels are of great interest in manufacturing hydrogel mask packs. We have used the cellulose in various forms such as powder, cotton fiber and cellulase treated cotton fiber to investigate the property changes of cellulose/hydrogel sheets. When 0.1% and 0.3% of cellulose powder were added to hydrogels, tensile strength of hydrogel sheets were decreased by 10% and 14% respectively. Vise versa, when 0.5 ~ 2 cm of cotton fibers were added, tensile strength of hydrogel sheets were significantly increased by about 20%. The hydrogels which contain cotton fibers also gave an excellent moisturizing effect. Especially cellolose/hydrogels containing cellulase-treated cotton fibers showed the best effect on retaining moisture content increasing upto 380% in comparison with the one containing untreated cotton as well as excellent dispersibility.