• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.4
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• pp.1-8
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• 2009

Accumulated slag mass was predicted to estimate accurate performance of kick motor (KM) system. The validation of numerical analysis was performed with mass flow rate measured at the 4th ground test of the KM. The study described here includes the internal flow field of KM at various time steps during burning. Slag mass accumulation was analyzed through the aluminum oxide particle paths to predict slag mass deposition. Numerical analysis to solve both flow field and droplet accumulation was performed with Fluent 6.3 program. Analysing the effects of the acceleration, starting position and diameters of the aluminum oxide particles, total slag mass accumulation was obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.62-67
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• 2009

Pt thin films on Cr or Ti interlayer were deposited onto a tungsten carbide(WC) substrate by the ion beam assisted DC magnetron sputtering. The various atomic percent of Cr and Ti underneath of the Pt films were prepared to examine the total thin film characteristics. The microstructure and surface analysis of the specimen were conducted by using the SEM, XRD and AFM. Mechanical properties such as hardness and adhesion strength of Pt thin film also were examined. The interlayer of pure Ti was formed with 40 nm thickness while that of pure Cr was done with 50 nm as standard reference. The growth rate of either Cr or Ti thin film was almost same under the same deposition conditions. The SEM images showed that anisotropic grain of Pt thin films consisting of dense columnar structures irrespectively grew from the different target compositions. The values of hardness and adhesion strength of Cr/Pt thin film coated on a WC substrate were higher than those of Ti/Pt thin film.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.81-84
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• 2002

The effects of the isoelectronic AI-doping of GaN grown by metal organic chemical vapor deposition were investigated for the first time using scanning electron microscopy (SEM), Hall measurements, photoluminescence (PL), and time-resolved PL. When a certain amount of Al was incorporated into the GaN films, the room temperature photoluminescence intensity of the films was approximately two orders larger than that of the undoped GaN. More importantly, the electron mobility significantly increased from 130 for the undoped sample to $500\textrm{cm}^2/Vs$ for the sample grown at a TMAl flow rate of $10{\mu}mol/min$, while the unintentional background concentration only increased slightly relative to the TMAl flow. The incorporation of Al as an isoelectronic dopant into GaN was easy during MOCVD growth and significantly improved the optical and electrical properties of the film. This was believed to result from a reduction in the dislocation-related non-radiative recombination centers or certain other defects due to the isoelectronic Al-doping.

• Journal of the Semiconductor & Display Technology
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• v.7 no.1
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• pp.29-34
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• 2008

In this paper, the DE(double erosion) cathode for the reactive magnetron sputtering system is developed for high deposition rate and high target utilization efficiency. The utilization efficiency of the developed DE cathode is 22% higher than that of normal SE(single erosion) cathode. Sputtering process for the nickel oxide thin films with the DE cathode is performed under the following conditions; power with $1kW{\sim}3kW$, pressure with 4mtorr and 8mtorr, oxygen flow ratio with $0%{\sim}80%$. As a result, the hysteresis phenomenon of discharge voltage in 4mtorr is lower than that in 8mtorr and the hysteresis phenomenon of discharge voltage is getting lower as the applied power is getting higher. The structure of cross section and surface roughness of the thin films are observed by FE-SEM and AFM. The structure of cross section of the thin films is columnar and the average surface roughness under oxygen flow ratio of 0%, 52.5% and 65.0% are $2.08{\AA}$, $2.20{\AA}$ and $0.854{\AA}$, respectively.

• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.295-299
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• 1998

The magnetic thin films can be prepared without vacuum process and under the low temperature(<100 $^{\circ}C$) by ferrite plating. We have performed ferrite plating of $Ni_xFe_{3-x}O_4$ (x=0.162~0.138) films on cover glass at the substrate temperature 80 $^{\circ}C$ and pH range of the oxidizing solution, 7.1~8.8. the crystal structure of the samples has been identified as a single phase of polycrystal spinel structure by x-ray diffraction technique. The deposition rate and the grain size of the film increased with the pH of oxidizing solution. The coercive force (H_C)$ decreased with the pH of oxidizing solution.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.52.2-52.2
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• 2009

Si 박막형 solar cell은 Si 결정형 solar cell대비 cost 및 대면적화 측면에서 장점을 가지고 있다. 그러나 amorphous Si의 경우 light soacking에 의한 열화 문제가 있고, microcrystalline Si의 경우 요구되는 효율 확보를 위하여 $1.5{\mu}m$ 이상 두께가 필요하며, 증착율이 $5{\AA}/sec$.이하인 단점이 있다. 본 연구에서는 high deposition rate로 microcrystalline Si를 증착하기 위하여 high frequency, high power PECVD를 이용하였으며, RF power, 증착온도, H2/SiH4 ratio의 3인자를 3수준으로 변화시킨 완전요인배치 실험을 실시하였다. 실험결과 증착율은 $8.0{\AA}/sec.{\sim}52.8{\AA}/sec$ 범위, crystalline fraction은 0%~83.3% 범위의 결과를 얻었으며, 결정이 형성된 조건에서는 XRD분석결과 $2\theta=28.5$ 및 47.5에서 Si (111), (220) peak을 확인할 수 있었다. Surface Profilometer 를 이용한 surface roughness의 경우 $6.3{\AA}\sim32.4{\AA}$ 범위의 결과를 얻었으며, crystalline Portion이 높을수록 surface roughness가 증가함을 알 수 있었다.

• Journal of the Korean Vacuum Society
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• v.21 no.4
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• pp.212-218
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• 2012

The optical properties of AZO thin films prepared by the RF mangnetron sputtering system was studied to research the dependance of chemical properties of substrate. The substrate was the SiOC film deposited by Inductively coupled plasma chemical vapor deposition with various gas flow rate of $O_2$ and Ar (DMDMOS). In accordance with the increase of Ar gas flow rates, the Si-O bond in the SiOC film increased and then progressed the amorphism. The roughness of AZO grown on SiOC film with high degree of amorphism decreased and then improved the flatness of surfaces. Moreover, the ultra violet emission with high intensity was spontaneously induced in the AZO film growed on SiOC film with high degree of amorphism.

• Archives of Pharmacal Research
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• v.14 no.4
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• pp.298-304
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• 1991

Isoprinosine, an antiviral agent with a bitter taste, has been clinically used up to a maximum of 4 g daily in 4-8 doses. In this investigation, isoprinosine was microencapsulated with ethylcellulose 22 cps, 50 cps and 100 cps by means of polymer deposition from cyclohexane through temperature change. Complete removal of cyclohexane from the microcapsules was necessary, since ethylcellulose-coated microcapsules obtained from cyclohexane medium were heavily solvated with cyclohexane and formed lumps even after drying. The displacement of cyclohexane by n-hexane during isolation of microcapsules (Method III) or the freezing of the anal-washed microcapsules before drying (Mothod II) provided the dried products which were more discrete microcapsules than those which were simply dried in the air overnight (Method I). Method III was especially the most effective procedure in preparing finer and more discrete microcapsules. The drug-release from microcapsules was influenced by the ratio of core to wall, the viscosity grade of ethylcellulose and the overall microcapsule size. The release rate was adequately fitted to both the first-order and the diffusion-controlled processes. It is therefore possible to design the release-controlled microcapsules with ethylcellulose of different viscosity along with various core to wall ratio.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.103-110
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• 1993

Abstract It has been attempted to make the copper-graphite composites by deposition of copper on the surface of graphite through the hydrogen reduction of copper chlorides. Both KISH and natural graphites of less than 325 mesh were used as substrates and the hydrogen reduction also was conducted in the range of 350-50$0^{\circ}C$. The distribution of copper on the surface of graphite was found to increase with the decrease of reduction temperature. In addition. the partial pressure of hydrogen played an important role in the overall rate of reduction which was substantially dominated by the chemical reaction on the surface of each particle. It was concluded that the reduction temperature should be maintained as low as possible to accomplish the well distribution of copper in the composites.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.328-333
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• 2004

Transparent ZnO:Al conductor films for the optoelectronic devices were deposited by using the capacitively coupled DC magnetron sputtering method. The effect of Al doping concentration and discharge power on the electrical and optical properties of the films was studied. The film resistivity of $8.5${\times}$10^{-4}$ $\Omega$-cm was obtained at the discharge power of 40 W with the ZnO target doped with 2 wt% $Al_2$$_O3$. The transmittance of the 840 nm thick film was 91.7% in the visible waves. Increasing doping concentration of 3 wt% $Al_2$$O_3$ in ZnO target results in significant decrease of film resistivity, which may be due to the formation of $Al_2$$O_3$ particles in the as-deposited ZnO:Al film and the reduced ZnO grain sizes. Increasing DC power from 40 to 60 W increases deposition rate by more than 50%, but can induce high defect density in the film, resulting in higher film resistivity.