• 청정기술
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• 제7권1호
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• pp.65-74
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• 2001

본 연구는 디젤엔진에서 배출되는 NOx환원용 촉매로서 산화반응에서 우수한 활성을 나타내고 있는 페롭스카이트상의 $LaCoO_3$을 sol-gel 공정을 이용하여 촉매코팅용액을 제조한 후, 이를 기존의 dip-coating방법보다 코팅시간, 코팅량, NO-CO 산화 환원 반응에 있어서 경제적이고 효율적인 modified dip-coating방법을 이용하여 촉매코팅필터를 제조하고 이를 후처리장치에 부착함으로써 디젤엔진에서 배출되는 배가스를 효과적으로 제거시키고자 한다. 실험결과, modified dip-coating방법이 기존의 dip-coating방법에 비해서 코팅에 소요되는 용액량이 8.3배 코팅시간 83.3배 단축되었으며, 코팅량은 2~3배정도 커지고, NO-CO 산화 환원 반응성도 1.1~1.8배 가량 증가하였다. 그리고 코팅점도는 $0.006202kg{\cdot}m/sec$을 이용하여 코팅횟수 2회, 코팅량은 88.56mg/g에서 우수한 반응을 보였다. 또한 세라믹 필터의 셀수에 있어서는 200 CPSI가 적절함을 확인할 수 있다.

• 한국표면공학회지
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• 제43권2호
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• pp.97-104
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• 2010

In this paper, we conducted MATLAB simulation using the reflectance formula and the Planck's black body radiation principle, for the purpose of identifying the opimum material and thickness of anti-reflective coating from double layered structures. We found that the optimum condition was obtained when refractive index of upper layer is 1.44 and that of lower layer is 2.29. As materials close to these refractive indices, $MgF_2$ as the upper layer and $HfO_2$, ZnS, $TiO_2$ as the lower layer were suggested. The best result in an average reflectance of 2.759% was obtained from a double layered structure of $MgF_2$ 94 nm/ZnS 55 nm.

• 한국축산식품학회지
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• 제43권6호
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• pp.1170-1182
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• 2023

The aim of this study was to determine the effect of chitosan (CH)-based nanocomposite coating applications [chitosan+TiO₂ (CHT) and chitosan+TiO₂+rosmarinic acid (CHTRA)] on changes in quality attributes of rainbow trout fillets during cold storage (4℃). Fish fillets were randomly divided into four groups and subjected to treatments (CH, CHT, CHTRA, and control). After treatments, the groups were packaged under a modified atmosphere (40% CO₂+30% O₂+30% N₂) and stored at 4℃ for 18 days. During cold storage, the samples were subjected to physico-chemical and microbiological analyses. During storage, CH, CHT, and CHTRA treatments showed lower aerobic mesophilic and psychrotrophic bacteria counts than the control. However, the differences between coating treatments were not significant. The highest mean pH value was determined in the control group. As the storage time increased, the thiobarbituric acid reactive substances value increased. At the end of the storage period, no significant differences were observed between the treatments, including in the control group. The total volatile basic nitrogen (TVB-N) level in the control group was above 25 mg/100 g on day 15 of storage. However, the TVB-N level in the treatment groups was below 20 mg/100 g on day 18. It was also determined that coating application×storage period interaction had a significant effect on all color parameters (p<0.01). At the end of storage, the highest CIE L* was observed in CHTRA treatment. However, the value of this treatment did not differ from that of the CH treatment.

• 한국세라믹학회지
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• 제35권3호
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• pp.303-309
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• 1998

The fabrication of Al2O3/Al composite by pressureless infiltration was investigated by the change of Mg and Si content in Al alloy infiltration process and infiltration atmosphere. The effect of alloying elements infiltration atmosphere and interfacial reactants between Al alloy matrix and Al2O3 particles were in-vestigated in terms of bendingstrength and harness test,. The fabrication of Al2O3/Al composite by the vestigated in terms of bending strength and hardness test. The fabrication of Al2O3/Al composite by the pressureless infiltration was done in nitrogen atmosphere with Mg in Al alloy. It was successfully fabricated at $700^{\circ}C$ according to Mg contents in Al alloy and infiltration condition. Because Mg in the Al alloy and ni-trogen atmosphere of infiltratio condition produced Mg-N compound(Mg3N2) it decreased the wetting an-gle between molten Al alloy and Al2O3 particles by coating on surface of Al2O3 particles. The fracture strength of Al2O3/Al-Mg composite was 800MPa and Al2O3/Al-Si-Mg composite was 400MPa. Si in Al alloy decreased the interfacial strength between Al alloy matrix and Al2O3 particles.

• 한국전기전자재료학회논문지
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• 제33권3호
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• pp.214-218
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• 2020

In this study, Mg_xZn_1-xO thin films, which can be applied not only to active layers of light-emitting devices (LEDs), such as UV-LEDs, but also to solar cells, high mobility field-effect transistors, and power semiconductor devices, are fabricated using the sol-gel method. ZnO and Mg_0.3Zn_0.7O solution synthesized by the sol-gel method and the thin film were grown by spin coating on a Si (100) substrate and sapphire substrate. The solutions are synthesized by dissolving precursor materials in 2-methoxyethanol (2-ME) solvent, and then monoethanolamine (MEA) was added to the mixed solution as a sol stabilizer. Zinc acetate dihydrate is used as a ZnO precursor, while Mg nitrate hexahydrate and Mg acetate tetrahydrate are used as an MgO precursor. Then, the optical and structural characteristics of the fabricated thin films are compared. The molar concentration of the Zn precursor in the solvent is fixed at 0.3 M, and the amount of the Mg precursor is 30% of Mg²⁺/Zn²⁺. The optical characteristics are measured using an UV-vis spectrophotometer, and the transmittance of each wavelength is measured. Structural characteristics are measured using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition analyses are performed using energy dispersive X-ray spectroscopy (EDS). The Mg_0.3Zn_0.7O thin film was well formed at the ratio of the Mg precursor added regardless of the type of Mg precursor, and the c-axis of the thin film was decreased, while the band gap was increased to 3.56 eV.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1758-1760
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• 1998

MgO Protecting layer in AC PDP prevents ion bombardment in discharge plasma. The MgO layer also has the additional importance in lowering the firing voltage due to a large secondary electron emission coefficient. Until now, the MgO protecting layer is mainly prepared by E-beam Evaporation. However, the optimum activation manufacturing process of MgO thin film wasn't well known. Therefore in this study, after MgO protecting layer is prepared on dielectric layer by E-beam evaporation and liquid MgO spin coating, we carried out activation process of MgO thin film as a parameter of Temperature, Operating time and Operating pressure. In addition, discharge characteristics are also studied as a parameter of activation conditions.

• 대한금속재료학회지
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• 제49권3호
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• pp.270-274
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• 2011

Plasma electrolytic oxidation (PEO) treatment was performed on squeeze cast AZ31 alloy and $Al_{18}B_4O_{33}w/AZ31$ composite. Scanning electron microscope (SEM) was employed to characterize the surface morphology and cross-section microstructure of the coating. The phase structures of the PEO coating were analyzed by X-ray diffraction (XRD). The corrosion resistance of the PEO coating was evaluated by electrochemical method. The results showed that the $Al_{18}B_4O_{33}$ whisker on the surface of the composite was decomposed and $MgAl_2O_4$ was formed in the PEO coating layer of $Al_{18}B_4O_{33}w/AZ31$ composite during PEO treatment. As a result, the electrochemical corrosion potential of the PEO coated $Al_{18}B_4O_{33}w/AZ31$ composite was increased compared with that of AZ31 alloy.

• 한국표면공학회지
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• 제44권3호
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• pp.82-88
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• 2011

A uniform chromium-free conversion coating treated with an alkaline phosphate- permanganate solution was formed on the AZ 31 magnesium alloy. The effect of acid pickling on the morphology and on the corrosion resistance of the alkaline phosphate-permanganate conversion coating was investigated. The chemical composition and phase structure of conversion coating layer were determined via optical microscopy, SEM, EDS, XPS and XRD. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to $2.4\;{\mu}m$. The alkaline phosphate-permanganate conversion coating was mainly composed of elements Mg, O, P, Al and Mn. The conversion-coated layers were stable compounds of magnesium oxide and spinel ($MgAl_2O_4$). These compounds were excellent inhibitors to corrosion. The electrochemical corrosion behaviors of coatings in 3.5 wt.% NaCl solutions were evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique. EIS results showed a polarization resistance of $0.1\;k{\Omega}$ for the untreated Mg and $16\;k{\Omega}$ for the alkaline phosphate-permanganate conversion treatment sample, giving an improvement of about 160 times. The results of the electrochemical measurements demonstrated that the corrosion resistance of the AZ 31 magnesium alloy was improved by the alkaline phosphate-permanganate conversion treatment.

• 한국결정성장학회지
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• 제28권2호
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• pp.80-84
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• 2018

AZ31과 AZ91 Mg 합금을 Na-P 및 Na-Si 전해질을 사용하여 전해질의 농도, 인가전압, 처리시간에 따라 여러가지 조건에서 PEO 처리하여 5%의 농도를 갖는 염수분무법으로 내부식성 연구를 하였다. 일반적으로 산화피막 코팅 두께가 증가하면 내부식성이 증가하였다. 코팅두께보다 산화피막 표면의 기공크기가 커지면 장기 내부식성은 나빠지는 경향을 보인다. 산화피막의 전체적인 산화물 결정상이 증가할수록, 또 MgO 결정상 대신 $Mg_2SiO_4$ 상과 같은 다른 결정상이 증가할수록 내부식성이 월등히 증가하는 것을 알 수 있었다.

• 공업화학
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• 제34권1호
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• pp.30-35
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• 2023

TiO₂ 졸을 사용하여 유리알 표면에 TiO₂ 코팅한 후 건조 처리한 시료(TB)와 소성한 시료(TBc)를 제조하였다. 이들 시료에 대한 TiO₂ 박막의 특성분석과 메틸렌블루 및 톨루엔의 광분해 실험을 수행하였다. FE-SEM, XPS 및 FTIR 분석 결과, TB 시료의 TiO₂ 박막은 스펀지 폼과 같은 형태이며 무정형 TiO₂와 일부 결정형 TiO₂가 존재하였다. TBc 시료의 TiO₂ 박막에는 결정형 TiO₂가 주로 존재하며 침상형 입자와 미세 입자들이 혼재하였다. TBc 시료(46 mg/g)의 톨루엔 흡착량은 같은 코팅량의 TB 시료 대비 적었으나 톨루엔 분해율은 비슷했다. TB 시료의 경우, TiO₂ 코팅량이 증가함에 따라 톨루엔 분해능이 흡착능에 비해 적게 감소하였다. 이러한 결과는 소성하지 않은 TB 시료는 TiO₂ 코팅량이 증가하면 무정형 텍스처의 비표면적은 감소하는 반면 결정성 입자들의 활성점 감소는 적게 일어나기 때문으로 판단된다.