• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.854-860
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• 2004

"Research and Development of Melt-Growth Composite (MGC) Ultra High Efficiency Gas Turbine System Technology" program has been started in JFY2001. The main objective of the program is to establish basic component technologies to apply MGC material to an efficient gas turbine system successfully. It is known that MGC material maintains its mechanical strength at room temperature up to about 2000 K, which is ideal for the high temperature gas turbine. The purposes of the present study are to develop the cooling structure of the gas turbine combustor liner where MGC material is applied as the heat shield panel, also to develop the low NOx combustion system for a 1970 K (1700 deg.C) class gas turbine combustor. To start with, basic heat transfer characteristics were investigated by one-dimensional calculation and heat transfer experiment for the cooling structure. Axially staged configuration and fuel preparation were investigated by CFD calculation and experiments for the low NOx combustor.

• 한국전기전자재료학회논문지
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• 제23권5호
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• pp.418-423
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• 2010

Carbon nanotubes (CNTs) were synthesized by Fe-catalytic chemical vapor deposition (CVD) method about $800^{\circ}C$. The influence of process parameters such as pretreatment conditions, gas flow ratio, processing time, etc on the growth of CNTs was investigated by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Ammonia was added to acetylene source gas before and during the CNT growth. Different types of CNTs formed depending upon the processing condition. It was found that ammonia prevented amorphous carbons from adsorbing to the outer wall of CNT, resulting in purification of CNTs during CNT growth.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2006년도 춘계학술발표논문집
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• pp.298-301
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• 2006

DC-Motor is needed more and more sophisticated control to follow the highest precision of industrial automation and used in a number of control equipment or industrial fields. It is also useful to control single crystal($Al_2O_3$) growth. It is possible to procure a quality crystal utilizing a DC-Motor, if you mix Hydrogen and Oxygen gas properly and keep proper temperature in accordance with time process. In this paper, we will study about electrical valve positioning system for the gas mixture to improve the quality of single crystal($Al_2O_3$) growth and we will design about realtime monitoring systems of the automatic gas contol DC- Motor for single crystal($Al_2O_3$) growth

• 한국세라믹학회지
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• 제31권1호
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• pp.88-96
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• 1994

Hot filament-assisted CVD was carried out to deposit diamond films on Si(100) substrate at 90$0^{\circ}C$ using a 1% CH4-H2 mixture gas. Deposition was made at various conditions of mass flow rate of the feed gas (30~1000 sccm), pressure (2.5~300 Torr), and filament-substrate distance (4~15 mm), and the deposited films were characterized by SEM, XRD, and Raman spectroscopy. As the flow rate increases, the growth rate also increased but the crystallinity of the film was degraded. A longer filament-substrate distance simply caused both the growth rate and the crystallinity to become poorer. On the other hand, the pressure variation resulted in a maximum growth rate of 2.6 ${\mu}{\textrm}{m}$/hr at 10 Torr and the best film quality around 50 Torr, exhibiting an optimum condition. The observed trends were interpreted in terms of the flow velocity-dependent pyrolysis reaction efficiency and mass transport through the boundary layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.174-175
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• 2005

Initial growth stage was investigated for SiC homoepitaxial film growth using 'step controlled epitaxy' technique. When the off angel direction is located parallel along to the gas flow direction, the smoother surface can be obtained. On the on axis substrates, selective etching was detected both the etching and growth condition. It was deduced that the high ratio of C/Si in the source gas results in well developed steps and etched spiral around micropipes.

• 미생물학회지
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• 제9권3호
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• pp.95-102
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• 1971

The growth characteristics of Candida tropicalis KIST 351 on gas oil substrate under different culture conditions were investigated and the preliminary animal feeding experiments using this yeast as a partial substitute of fish meal was also conducted. The yeast assimilates effectively n-paraffins in gas oil ranging from $C_{16}$ to $C_{16}$ with its maximum cell growth at $33^{\circ}C$ and pH 5.5 with aeration of 3 vvn and agitation of 900 rpm. The optimal concentrations of nitrogen sources, $HK_2PO_4$ and $Na_2HPO$ were 4, 2 and 0.5g/1, respectively. Ferrous sulfate, manganese sulfate and zinc sulfate showed positive effect to cell growth with the optimal range of 5-10 ppm. In the feeding experiment with 3 and 5% incorporation of the gas oil grown yeast, neither adverse effects on growth of chicks nor toxic effect were observed. Protein content of the dried cell was 58.8% and its amino acid composition compared well with other single-cell protein products and FAO reference protein.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.223-228
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• 1997

The gas dynamics in a stagnation point upflow OMVPE reactor were studied by Raman spectroscopy. The gas temperature was measured as a function of inlet gas velocity and aspect ratio for both H$_2$ and N$_2$ carrier gases. The centerline temperature gradient was latger at higher inlet velocities and with the use of N$_2$, and only weakly dependent on the aspect ratio. a tracer molecule, CH$_4$, was used to investigate the steady state behavior of reactants in the reactor, and the use of a sweeping flow was found to be a suitable method for preventing wall deposition. The transient switching response of the gas manifold was also investigated. Under certain conditions (low velocities, unmatched flows) recirculation flows were apparent. Numerical calculations of the reactor gas dynamics gave reasonable agreement with experimental results when detailed thermal boundary conditions were included.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.145-150
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• 2018

A new methodology, the crack-spallation model, has been developed to analyze gas-solid reactions dominated by crack growth inside of the solid reactant and spallation phenomena. The new model physically represents three processes of the reaction progress: (1) diffusion of gas reactant through pores; (2) growth of product particle in pores; and (3) crack and spallation of solid reactant. The validation of this method has been conducted by comparison of results obtained in an experiment for oxidation of $UO_2$ and the shrinking core model. The reaction progress evaluated by the crack-spallation model shows better agreement with the experimental data than that evaluated by the shrinking core model. To understand the trigger point during the reaction progress, a detailed analysis has been conducted. A parametric study also has been performed to determine mass diffusivities of the gas reactant and volume increase constants of the product particles. This method can be appropriately applied to the gas-solid reaction based on the crack and spallation phenomena such as the voloxidation process.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
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• pp.91-95
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• 1998

Selectivity of SiC deposition on a Si substrate partially covered with a masking material was investigated by introducing HCl gas into hexamethyldisilane/H2 gas system during the deposition. the schedule of the precursor and HCl gas flows was modified so that the selectivity of SiC deposition between a Si substrate and a mask material should be improved. It was confirmed that the selectivity of SiC deposition was improved by introducing HCl gas. Also, the pulse gas flow technique was effective to enhance the selectivity.

• 한국재료학회지
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• 제28권4호
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• pp.241-246
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• 2018

$TaN_x$ film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using $NH_3$ as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using $N_2+H_2$ mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown $TaN_x$ film with $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. For a comparison, reactive sputter-grown $TaN_x$ film with $N_2$ is also studied. The results reveal that ALD-grown $TaN_x$ films with $NH_3$ and $H_2$ include a metallic Ta-N bond, which results in the film's higher conductivity. Meanwhile, ALD-grown $TaN_x$ film with a $N_2+H_2$ mixed gas or sputtergrown $TaN_x$ film with $N_2$ gas mainly contains a semiconducting $Ta_3N_5$ bond. Such a different portion of Ta-N and $Ta_3N_5$ bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.