• 한국세라믹학회지
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• 제26권3호
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• pp.331-340
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• 1989

In this study, it was tried to deposit diamond films from a mixture of CH4 and H2 by the microwave plasma chemical vapor deposition(MWCVD). The MWCVD process was designed and set up from the 2.45GHz microwave generator. And the diamond film was successfully deposited on silicon wafers from the mixture of methane and hydrogen. The microstructures of the deposited diamond films were studied by using the following deposition variables : (a) methane concentration(0.6-10%), (b) reaction pressure(10-100torr), and (c) the substrate temperature(450-76$0^{\circ}C$).

• 한국동물학회지
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• 제38권3호
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• pp.417-425
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• 1995

적외선 온도 감응기를 장착한 기존의 마이크로파 고정기의 단점을 보완하기 위해서 주변 온도를 보상할 수 있는 고정기를 개발하였다. 이를 이용하여 흰쥐의 혀, 췌장 및 소장을 고정(물리고정)한 후 몇 가지 염색법을 적용하여 염색성을 관찰하였고, 췌장의 내, 외분비 세포의 미세구조를 전자현미경으로 검경하였으며 단백질의 양과 bands의 양상을 조사하였다. 또한 이 결과들을 통상적인 화학고정을 시행한 경우와 비교하여 마이크로파에 의한 생체물질의 고정효과를 검증하고 조직화학에 응용될 수 있는지를 조사하였다. 흰쥐 혀의 횡단면을 H-E 염색하였을 경우, 두 고정법에서 염색성은 유사하였으나 물리고정에 비해 화학고정에 의한 관찰된 조직은 근육층의 분리가 관찰되었다. 췌장조직을 Feulgen 반응을 이용하여 염색하였을 경우, 물리고정한 군에서 반응산물이 보다 명확하게 관찰되었으며, 십이지장 융모에서 PAS 반응에 의한 염색성도 물리고정의 경우에서 배상세포에 특이적으로 강하게 나타났다. 물리고정을 한 후 짧은 시간동안 2차로 화학고정했을 경우, 췌장 내, 외 분비세포들의 전자현미경적 미세구조는 막 구조 및 세포기관이나 분비과립등의 보존상태 등에서 통상적인 화학고정법의 결과와 유사하게 관찰되었다. 물리고정한 시료의 질과 염색성이 우수하다는 사실에 근거하여 단백질 함량을 조사한 결과, 물리고정시 단백질의 추출이 비교적 적은 것으로 조사되었다. 이상과 같은 결과들은 마이크로파로 생체조직을 고정할 경우 대부분의 단백질들의 불용성화가 일어남으로써 미세구조의 고정 및 염색성이 증대되는 것으로 판단되었다. 현상에는 반드시 rosy transformant의 염색체 삽입에 의해서 만이 아니라 세포질내에서도 construct내의 rosy 유전자의 발현이 가능한 것으로 분석되었다. 또한 형질전환율에 있어서는 Pc[(ry+)B]와p[(ry+)$\Delta$SX9] construct 간에 유의한 차가 없는 것으로 나타났다. 이상의 결과로 볼 때, 실험 목적에 따라 자율적인 P element 또는 helper DNA를 이용한 비자율적인 P element를 효과적인 vector 로 선택 이용함으로써 특정 유전자를 곤충집단내로 침투 및 고정시킬 수 있다고 판단된다.

• 한국재료학회지
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• 제20권1호
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• pp.42-46
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• 2010

Phosphorus exhibits considerable segregation in steelmaking slag. In order to recover phosphorus from slag to $K_3PO_4$ via molten iron, a carbothermic reaction using microwave heating was suggested recently. The carbothermic reduction of phosphorus from slag to molten iron using microwave heating was carried out at 2073K. However, at this temperature the thermodynamic properties of both slag and molten iron cannot be determined experimentally. Therefore, the computational approach of the so-called CALPHAD method is very useful to understand the transfer of phosphorus from slag to metal and to enhance this reaction. In the present investigation, a theoretical study of the reduction behavior of phosphorus in slag was carried out at much lower temperatures using the recently developed thermodynamic database in the FactSage program. The calculated results showed reasonable accordance with the experimental data; namely, the thermodynamic database could be applied successfully to higher temperature reactions. The current study found that higher temperature and high $SiO_2$ concentration are favorable for the recovery of phosphorus from slag.

• 한국표면공학회지
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• 제29권5호
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• pp.540-544
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• 1996

To apply the CVD diamond film to coated tools, it is necessary to make adhesion strength between diamond film and substrate stronger. So adhesion strength of diamond coated WC-Co tools using Microwave Plasma CVD and cutting test of Al-18mass%Si alloy using diamond cutting tools were studied. Diamond coating was carried out using Microwave Plasma CVD apparatus. Reaction gas was used mixture of methane and hydrogen. Substrate temperature were varied from 673K to 1173K by control of microwave output power and reaction pressure. By observation of SEM, grain size became larger and larger as substrate temperature became higher and higher. Also all deposits were covered with clear diamond crystals. XRD results, the deposits were identified to cubic diamond. An analysis using Raman spectroscopy, the deposit synthesized at lower substrate temperature (673K) showed higher quality than deposit synthesized at higher substrate temperature (1173K). As a result of scratch adhesion strength test, from 873K to 1173K adhesion strength decreased by rising of substrate temperature. The deposit synthesized at 873K showed best adhesion strength. In the cutting test of Al-18mass%Si alloy using diamond coated tools and the surface machinability of Al-Si works turned with diamond coating tools which synthesized at 873K presented uniform roughness. Cutting performance of Al-18mass%Si alloys using diamond coated WC-Co tools related to the adhesion strength.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.288-289
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• 2006

We studied the effect of sol-gel processing and sintering temperature on the microwave properties of $MgCo_2(VO_4)_2$ system(MCV) which is applicable to LTCC(low-temperature cofired ceramics). The MCV was synthesized by sol-gel process using solution that contains precursor molecules for Mg, Co, and V. SEM analysis shows that the average particle size is ${\sim}1{\mu}m$ and size distribution is very uniform compared to the one prepared by conventional solid-state reaction process. Highly dense samples were obtained at the sintering temperature range of $750^{\circ}C{\sim}930^{\circ}C$. The maximum $Q{\times}f_0$ value of 55,700GHz, dielectric constant(${\varepsilon}_r$) of 10.41 and temperature coefficient(${\tau}_f$) of $-85ppm/^{\circ}C$ was obtained at the sintering temperature of $930^{\circ}C$. The superior microwave properties of sol-gel processed MCV relative to conventional solid-state reaction processed one is remarkable especially at lower sintering temperatures such as $750^{\circ}C$ and $800^{\circ}C$.

• 한국식품영양과학회지
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• 제30권6호
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• pp.1026-1032
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• 2001

Microwave 처리가 쌀가공 부산물로 발생하는 왕겨와 미 의 항산화능에 미치는 영향을 조사하였다. 100 W, 200 W, 440 W의 출력으로 microwave를 처리하였을 때, 출력과 처리시간에 비례하여 갈변을 나타내는 색도의 변화가 관찰되었다 그러나, 왕겨와 미강의 전자공여능은 조사된 범위 내에서 microwave처리에 대해 큰 변화를 보이지 않았다. 활성산 소종($H_2O$$_2$,O$_2$$^{-}$, .OH)을 발생시켜 어유의 과산화에 대한 왕겨와 미강의 과산화 억제력을 조사한 결과, 전반적으로 왕겨가 미강보다 microwaye 처리에 안정함을 보였다 특히, $H_2O$$_2$에 대한 왕겨의 과산화 억제력은 미강에 비하여 매우 높게 측정되었다. 이상의 결과로 왕겨가 미강보다 항산화 물질을 많이 함유함으로써 미강보다 높고 안정한 항산화능을 나타내 고, 또한 microwave 처리로 인하여 항산화 물질이 일부 파괴되지만 항산화력을 가지는 갈변 반응 생성물이 생성되어 왕겨의 경우에는 microwave 처리에 대해 영향을 거의 받지 않 음을 알 수 있었다. 따라서, microwave 처리 공정은 왕겨나 미강의 항산화능을 이용한 가공 방법에 이용될 수 있음을 의미한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.889-892
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• 2009

A microwave plasma torch at the atmospheric pressure by making use of magnetrons operated at the 2.45 GHz and used in a home microwave oven has been developed. This electrodeless torch can be used to various areas, including industrial, environmental and military applications. Although the microwave plasma torch has many applications, we in the present work focused on the microwave plasma torch operated in pure steam and several applications, which may be used in future and right now. For example, a high-temperature steam microwave plasma torch may have a potential application of the hydrocarbon fuel reforming at one atmospheric pressure. Moreover, the radicals including hydrogen, oxygen and hydroxide molecules are abundantly available in the steam torch, dramatically enhancing the reaction speed. Also, the microwave plasma torch can be used as a high-temperature, large-volume plasma burner by injecting hydrocarbon fuels in gas, liquid, and solid into the plasma flame. Lastly, we briefly report an underway research, which is remediation of soils contaminated with oils, volatile organic compounds, heavy metals, etc.

• Journal of Forest and Environmental Science
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• 제31권1호
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• pp.1-6
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• 2015

Microwave assisted biodiesel production from crude Pongamia pinnata oil using homogeneous base catalyst (KOH) was unsuccessful because of considerable soap formation. Therefore, a two step process of biodiesel production from high free fatty acid (FFA) oil was investigated. In first step, crude P. pinnata oil was acid catalyzed using $H_2SO_4$ and acid value of oil was reduced to less than 4 mg KOH/g. Effect of sulfuric acid concentration, alcohol-oil molar ratio and microwave irradiation time on acid value of oil was studied. Result suggested that 1.5% $H_2SO_4$ (w/w), 6:1 methanol oil molar ratio and 3 min microwave irradiation time was sufficient to reduce the acid value of oil from 12 and 22 mg KOH/g to 2.9 and 3.9 mg/KOH/g, respectively. Oil obtained after pretreatment was subsequently used for microwave assisted alkali catalyzed transesterification. A higher biodiesel yield (99.0%) was achieved by adopting two step processes. Microwave energy efficiency during alkali catalyzed transesterification was also investigated. The results suggested a significant energy saving because of reduced reaction time under microwave heating.

• Journal of Biosystems Engineering
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• 제32권2호
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• pp.121-129
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• 2007

This study was conducted to elucidate extraction efficiency by microwave technique in comparison with sonication technique for extraction of insecticide residue in pear. In the analysis of the extraction efficiency of microwave for a pear spiked with imidacloprid, the extraction efficiency by microwave power of 300 W with extraction temperature of $80^{\circ}C$, heating time of 1 to 3 minute was shown to be similar with the extraction time 20 minutes by sonication. The optimal condition. in consideration of economical condition and treatment time, for microwave extraction of imidacloprid in the pear were 300 watts of power supply, $100^{\circ}C$ of extraction temperature, 1 minute of heating time and 10 mL of acetone volume. A new microwave vessel was developed to rapidly process the sample of the insecticide imidacloprid residues in the pear. This vessel was designed to include a reaction chamber and a filtration equipment, and a gathering chamber. The system could curtail a pretreatment time to 21 minutes than sonication and 7.9 minutes than the previous microwave vessel.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.352-355
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• 1998

Dense $ Pb(Zr, Ti)O_3(PZT)/Al_2O_3$ nanocomposites were prepared by the 28 GHz microwave heating method and conventional electric furnace sintering. Electrical and mechanical properties of the composites were investigated. The fracture strength of the PZT composites with 0.1vol% $Al_2O_3$ was significantly improved in both sintering methods. Smaller grain size and effective reinforcement of the PZT matrix by the second phase were considered to be responsible for the excellent fracture strength. Planar electromechanical coupling factor Kp of the composites sintered by 28GHz microwave heating was higher than that of the materical prepared by the conventional route. It seemed that the control of the reaction between PZT and $Al_2O_3$ by the microwave rapid sintering resulted in the high piezoelectric properties.