• 한국표면공학회지
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• 제29권5호
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• pp.577-584
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• 1996

Silicon oxide films with high hardness and water repellency were prepared by microwave plasma-enhanced CVD using four kind of organosilicon compound-fluoro-alkyl silane mixtures as source gases. An argon gas was used as a carrier gas for fluoro-alkyl silane. The substrate temperatures during deposition were controlled by resistant heating at a constant value between 50 and $300^{\circ}C$. The hardness of the films increased, but the deposition rate and the contact angle for a water drop decreased with increasing substrate temperature. The number of methoxy groups also affected the water repellency and hardness. The deposited films became more inorganic with increasing substrate temperature because of the thermal dissociation of reactants.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1103-1105
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• 1993

Microwave characteristics of the system (1-X) ${Na}_{1/2}{Sm}_{1/2}TiO_3$[NST]-X ${Li}_{1/2}{Nd}_{1/2}TiO_3$[LNT] were investigated. The dielectric constant and unloaded Q were 86,1950 respectively for NST at 3GHz and 80,500 for LNT. 0.4 NST - 0.6 LNT system has the dielectric constant ${\varepsilon}r$=86.2, Q=930(3GHz), temperature coefficient of the resonant frequency ${\tau}f$ = 8 ppm/$^{\circ}C$ when sintered at $1450^{\circ}C$ for 2h.

• 한국식품과학회지
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• 제37권2호
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• pp.268-273
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• 2005

끓는 물에 의한 재래적인 방법과 전자렌지를 이용하여 데치는 방법이 시금치의 phytochemical 성분 및 위해성 요인의 변화에 미치는 영향을 살펴보았다. ${\beta}$-Carotene과 chlorophylls 함량은 데치기에 의해 대조군보다 유의적으로 증가하였으며, 특히 재래적인 방법이 전자렌지에 의한 방법보다 높은 함량을 보였는데 chlorophyll a 함량은 유의적으로 증가한 반면 ${\beta}$-carotene과 chlorophyll b 함량은 단지 함량만 증가하였을 뿐 유의적인 차이는 없었다. Ascorbic acid와 총 flavonoid 및 총 polyphenol 함량은 데치기에 의해 모두 감소하였으며, 전자렌지에 의한 방법이 재래적인 방법보다 높은 함량을 보였다. 이때 전자렌지에 의해 데쳤을 경우 ascorbic acid는 대조군과 유의적인 차이 없이 감소하였으나, 총 flavonoid와 총 polyphenol은 대조군보다 유의적으로 낮은 함량을 보여 다소 영향을 받는 것으로 나타났다. 총균과 대장균군 수는 데치기에 의해 모두 유의적으로 감소하였으며 특히 끓는 물에 의한 재래적인 방법이 전자렌지에 의한 데치기보다 약 20-25% 정도 유의적으로 낮았다. Nitrate는 데치기에 의해 감소하는 경향을 나타냈으며 특히 전자렌지에 의한 방법이 재래적인 방법보다 낮은 함량을 보였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.33-33
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• 2003

• 한국재료학회지
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• 제13권4호
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• pp.259-265
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• 2003

For the aim of thin microwave absorbers used in mobile telecommunication frequency band, this study proposed a high permittivity dielectrics(λ/4 spacer) coated with ITO thin films of 377 $\Omega$/sq(impedance transformer). High frequency dielectric properties of ferroelectric ceramics, electrical properties of ITO thin films and microwave absorbing properties of ITO/dielectrics were investigated. Ferroelectric materials including $BaTiO_3$(BT), 0.9Pb($Mg_{1}$3/Nb$_{2}$3/)$O_3$-0.1 $PbTiO_3$(PMN-PT), 0.8 Pb (Mg$_{1}$3/$Nb_{2}$3/)$O_3$-0.2 Pb($Zn_{1}$3$_Nb{2}$3/)$O_3$(PMN-PZN) were prepared by ceramic processing for high permittivity dielectrics,. The ferroelectric materials show high dielectric constant and dielectric loss in the microwave frequency range. The microwave absorbance (at 2 ㎓) of BT, 0.9PMN-0.1PT, and 0.8PMN-0.2PZN were found to be 60%(at a thickness of 3.5 mm), 20% (2.5 mm), and 30% (2.5 mm), respectively. By coating the ITO thin films on the ferroelectric substrates with λ/4 thickness, the microwave absorbance is greatly improved. Particularly, when the surface resistance of ITO films is closed of 377 $\Omega$/sq, the reflection loss is reduced to -20 ㏈(99% absorbance). This is attributed to the wave impedance matching controlled by ITO thin films at a given thickness of high permittivity dielectrics of λ/4 (3.5 mm for BT, 2.5 mm for PMN-PT and PMN-PZN at 2 ㎓). It is, therefore, successfully proposed that the ITO/ferroelectric materials with controlled surface resistance and high dielectric constant can be useful as a thin microwave absorbers in mobile telecommunication frequency band.

• 생약학회지
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• 제45권4호
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• pp.320-325
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• 2014

The purpose of this study is to develop a new preparation process of Notoginseng root(Panax notoginseng) extracts having high concentrations of ginsenoside $Rg_3$, $Rg_5$, $Rk_1$ and $Rh_4$, a special component of Red and Black ginseng(Panax ginseng). Chemical transformation from ginseng saponin to prosapogenin was analyzed by the HPLC. Extracts of Notoginseng root was processed under several treatment conditions including microwave and vinegar(about 14% acidity) treatments. Results of those treatments showed that the quantity of ginsenoside $Rg_3$ increased by over 7.6% at 15 minutes of pH 2~4 vinegar and microwave treatments. The results of processing with MPN-15 indicate that the microwave and vinegar(about 14% acidity) processed Notoginseng root extracts that had gone through 15-minute treatments were found to contain the largest amount of ginsenoside $Rg_3$(7.639%), $Rg_5$(6.061%), $Rk_1$(1.516%) and $Rh_4$(1.599). It is thought that such results provide basic information in preparing Notoginseng root extracts with functionality enhanced.

• 한국물환경학회지
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• 제30권5호
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• pp.486-490
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• 2014

Industrial use of microwave heating as an alternative to conventional heating is becoming popular mainly due to dramatic reductions in reaction time. Therefore, this work experimentally determined the effect of microwave irradiation on ammonia nitrogen removal in wastewater. The effects of air flow rate (0.3~0.9 L/min), treatment temperature ($70{\sim}100^{\circ}C$), and initial pH (9~11) were characterized. As the air flow rate increased from 0.3 to 0.9 L/min, the ammonia removal rate constant (k) increased from -0.6642 to $-1.0755min^{-1}$. As the temperature increased from 70 to $100^{\circ}C$, k increased -0.0338 to $-1.0755min^{-1}$. As the pH increased from 9 to 11, k increased -0.2443 to $-1.0755min^{-1}$. Ammonia removal was strongly dependent on temperature and pH rather than air flow rate. The results show that microwave irradiation is effective in ammonia nitrogen removal in wastewater due to advantages of fast and effective processing.

• Current Optics and Photonics
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• 제4권4호
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• pp.361-367
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• 2020

An approach based on an integrated photonic Ti:LiNbO₃ Y branch has been proposed, designed, and analyzed for the microwave instantaneous frequency measurement (IFM). By designing the Y branch with length L = 6545 ㎛ and refractive index N_TE - N_TM = 0.0764, a complementary optical filter with free spectral range (FSR) of 600 GHz is constituted, which results in a maximum measureable frequency of 300 GHz being obtained. Theoretical analysis on the temperature stability of the Ti:LiNbO₃ Y branch shows that the FSR variation of the complementary filter is 0.3% for the temperature change of 100 K, which indicates that the IFM approach will have a better stability. All these results demonstrate that the proposed IFM approach has potential capability to be used for the increasingly higher microwave IFM with better stability.

• Journal of Electrochemical Science and Technology
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• 제11권2호
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• pp.180-186
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• 2020

In this work, a metal-ligand solution (Cu-EDTA) was prepared based on the molecular precursor method and the solution was spin-coated onto 3D printed flexible photosensitive resin sheets. After being processed by microwave, a laser with a wavelength of 355 nm was utilized to scan the spin-coated sheets and then the sheets were immersed in an electroless copper plating solution to deposit copper wires. With the help of microwave processing, the adhesion between copper wires and substrate was improved which should result from the increase of roughness, decrease of contact angle and the consistent orientation of coated film according to the results of 3D profilometer and SEM. XPS results showed that copper seeds formed after laser scanning. Using the 3D printed flexible sheets as cathode and galvanized iron as anode, electrochemical machining was conducted.

• 소성∙가공
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• 제29권4호
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• pp.179-187
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• 2020

Existing composite forming processes such as the autoclave, prepreg compression forming (PCF), RTM, etc. require high production costs because of their long processing time. On the other hand, microwave heating process (MHP) can reduce the production costs since both mold and composite material can be heated directly. The aim of this study is to manufacture a mold consisting of polytetrafluoroethylene (PTFE), quartz glass, stainless steel clamps, and polyether ether ketone (PEEK) bolts for fabricating FML based on self-reinforced polypropylene (SRPP) using the MHP. First, the flame test was carried out prior to the MHP to check the temperature on the mold and whether the spark occurred at the mold and the edge of the FML. Second, the uniaxial tensile test was then conducted to obtain the mechanical properties of the FML manufactured by the MHP. The mechanical properties were compared with those of the FML fabricated by the PCF. As a result, the MHP using the PTFE mold can manufacture the FML more rapidly than the PCF, and obtain acceptable mechanical properties.