• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1825-1826
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• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2006.04a
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• pp.488-489
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• 2006

• Toxicological Research
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• v.5 no.2
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• pp.89-96
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• 1989

Rapid and complete epidermal-dermal separation procedure were determined in neonatal rat skin by light microscopic observation and by compairing enzyme activities in the separated epidermis. Microscopic appearance demonstrated the at four different separation procedures used in the study resulted in good separation of epidermis from dermis` heating method (i.e., immersion in 55C water for 30 sec, followed by immersion in 0-4C water) and microwave irradiation for 10 sec were saving time.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.3
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• pp.311-319
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• 2013

The purpose of the present study is to investigate the effects of green tea catechin on microsomal phospholipase $A_2(PLA_2)$ activity and the arachidonic acid (AA) cascade in hearts of microwave exposed rats. Sprague-Dawley male rats weighing $100{\pm}10$ g were randomly assigned to one normal group and three microwave exposed groups. The microwave exposed groups were subdivided into three groups: catechin free diet (MW) group, 0.25% catechin (MW-0.25C group and 0.5% catechin (MW-0.5C) group according to the levels of dietary catechin supplementation. Rats were sacrificed $6^{th}$ day after microwave irradiations (2.45 GHz, 15 min). The heart microsome $PLA_2$ activity in the MW group was 130% greater than that of normal groups, whereas there was no significant difference between normal group and MW-0.25C, MW-0.5C group. The per- centage phosphatidyl ethanolamine (PE) hydrolyzed in the heart microsome in the MW was increased 54% by microwave irra- diation, whereas there was no significant difference between normal group and MW-0.5C group. The percentage phosphatidyl choline (PC) hydrolyzed in the heart microsome in the MW group was increased by 104% and by microwave irradiation, whereas there was no significant difference between normal group and MW-0.5C group. The formation of thromboxane $A_2(TXA_2)$ in the heart microsome was 70% greater in the MW group than in the normal group. However, the MW-0.25C and MW-0.5C group maintained the normal level. The formation of prostacyclin ($PGI_2$) in the heart microsome was 21% lower in the MW group than in the normal group, while that of MW-0.25C and MW-0.5C group were maintained in the normal group. The heart microsomal thiobarbituric acid reactive substances (TBARS) concentrations, as an index of lipid peroxide, were 71% greater in the MW group, as compared with normal group. However, the MW-0.25C and MW-0.5C group were 4.6% and 9.2% lower, respectively, than that of MW group. In conclusion, heart function appeared to be improved by green tea catechin supplementation due to its antithrombus action, which in return controls the AA cascade system.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.280-284
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• 2016

In this study, the extractable content of each parameters from angelica was confirmed using conventional solvent extraction and microwave extraction in order to extract the functional active ingredient. In addition, the functionality of active ingredients was evaluated by measuring the antioxidant activity and the flavonoids and total polyphenols of the active ingredient extracted from angelica, For the conventional solvent extraction at optimal conditions of the extraction time (2 h), ethanol/pure water volume ratio (60%), the extraction temperature ($60^{\circ}C$), 20.6 wt% of the active ingredient were extracted. Also, when using microwave extraction at optimal conditions of the microwave irradiation time (6 min), microwave intensity (600 W) and ethanol/pure water volume ratio (60 vol%) 22.8 wt% of the active ingredient were extracted. The microwave method required shorter time to complete extraction compared to that of using the conventional solvent extraction method. The antioxidant activity of active ingredients extracted from angelica was 31.46% of DPPH radical scavening activity. The flavonoid content was 14.20 mg QE/mg dw, and total polyphenol content was 11.70 mg GAE/g when using the microwave extraction process.

• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.53-57
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• 2004

The purpose of this study was to investigate the effects of green tea catechin on mixed function oxidase system (MFO), lipofuscin contents, carbonyl value, oxidative damage and the antioxidative defense system in lung of microwave exposed rats. Experimental groups were divided to normal group and microwave exposed group. The microwave exposed groups were subdivided into three groups: catechin free diet (MW-0C) group, 0.25% catechin (MW-0.25C) group and 0.5 ％ catechin (MW-0.5C) group according to the levels of dietary catechin supplementation. The rats were irradiated with microwave at frequency of 2.45 GHz for 15 min. Experimental animals were sacrificed at 6th day after microwave irradiation. The contents of cytochrome P$_{450}$ contents in MW-0C group was increased to 95% , compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 16% and 31%, respectively, compared with MW-0C group. The activity of NADPH-cytochrome P$_{450}$ reductase in MW-0C group was increased to 44%, compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 12% and 17％, respectively, compared with MW-0C group. The activity of superoxide dismutase (SOD) in MW-0C group was decreased to 21 ％, compared with normal group. MW-0.25C and MW-0.5C group were significantly (p < 0.05) increased, compared with MW-0C group. The activity of glutathione peroxidase (GSHpx) in MW-0C group was significantly decreased, compared with normal group. MW-0.25C and MW-0.5C groups were recovered to the level of normal group. The thiobarbituric acid reactive substances (TBARS) content in MW-0C group was increased to 34 ％, compared with normal group. Catechin supplementation groups were maintained the level of normal group. The levels of caybonyl value in MW-0C group was increased to 21 ％, compared with normal group. MW-0.25C and MW-0.5C groups were reduced to 14% and 12%, respectively, compared with MW-0C group. The lipofuscin contents in MW-0C group were increased to 23.4 ％, compared with normal group. That of MW-0.5C group was significantly reduced, compared with MW-0C group. In conclusion, MFO system was activated and the formation of oxidized protein, lipofuscin was increased and antioxidative defense system was weakened of lung tissue in microwave exposed rats, thus oxidative damage was increased. But it was rapidly recovered to normal level by green tea catechin supplementation.n.

• Korean Journal of Materials Research
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• v.17 no.12
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• pp.669-675
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• 2007

Hydroxyapatite (HAp) and biphasic calcium phosphate (BCP) nano powders were synthesized using the microwave-assisted synthesis process dependent on pH and microwave irradiation time. The average size of a powder was less than 100 nm in diameter. Through in-vitro cytotoxicity tests by an extract dilution method, the HAp and BCP nano powders have shown to be cytocompatible for L-929 fibroblast cells, osteoblastlike MG-63 cells and osteoclast-like Raw 264.7 cells. The activation of osteoblast was estimated by alkaline phosphatase (ALP) activity. When the HAp and BCP were treated to MG-63 cells, alkaline phosphatase activities increased on day 3, compared with those of the untreated cells. Also, the collagen fibers increased when the HAp and BCP powders suspension were treated to MG-63 cells, compared to those of the untreated cells. Quantitative alizarin red S mineralization assays showed a trend toward increasing mineralization in osteoblast cultured with powder suspension. In conclusion, hydroxyapatite and biphasic calcium phosphate appeared to be a bone graft substitute material with optimal biocompatibility and could be further applied to clinical use as an artificial bone graft substitute.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.23-28
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• 2019

We report a supercapacitor cable, which consists of three-dimensional (3D) porous graphene coated onto the surface of carbon thread. The 3D porous framework of graphene was constructed by microwave-activated process using a graphene oxide-coated carbon thread. The use of microwave irradiation enabled to convert graphene oxide into reduced graphene oxide without any reducing agents and activate graphene sheets into exfoliated and porous graphene sheets. Combining two wire electrodes with a polymer gel electrolyte successfully completed supercapacitor device in a form of cable construction. The supercapacitor cables were highly flexible, and thus can be transformed into various shapes of devices and be integrated into textile items. A high area-capacitance of 38.1 mF/cm was obtained at a scan rate of 10 mV/s. This capacitance was retained 88% of its original value at 500 mV/s. The cycle life was also demonstrated by repeating a charge/discharge process during 10,000 cycles even under bent states, showing a high capacitance retention of 96.5%.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.262-262
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• 2016

최근 고해상도 디스플레이가 주목받으면서 기존 비정질 실리콘(a-Si)을 대체할 수 있는 재료에 관한 연구가 활발히 진행되고 있다. a-Si의 경우 간단한 공정 과정, 적은 생산비용, 대면적화가 가능하다는 장점이 있지만 전자 이동도가 매우 낮은 단점이 있다. 반면, 산화물 반도체는 비정질 상태에서 전자 이동도가 높으며 큰 밴드갭을 가지고 있어 투명한 특성을 나타낼 뿐만 아니라, 저온공정이 가능하여 기판의 제한이 없는 장점을 가지고 있다. 대표적으로 가장 널리 연구되고 있는 산화물 반도체는 a-IGZO(amorphous indium-gallium-zinc oxide)이다. 그러나 InZnO(IZO) 기반의 산화물 반도체에서 carrier suppressor 역할을 하는 Ga(gallium)은 수요에 대한 공급이 원활하지 못하여 비싸다는 단점이 있다. 그러므로 경제적이면서 a-IGZO와 유사한 전기적 특성을 나타낼 수 있는 suppressor 물질이 필요하다. 따라서 본 연구에서는 IZO 기반의 산화물 반도체에서 Ga을 Hf(hafnium), Zr(zirconium), Si(silicon)으로 대체하여 용액증착(solution-deposition) 공정으로 각각의 채널층을 형성한 back-gate type의 박막 트랜지스터(thin-film transistor, TFT) 소자를 제작하였다. 용액증착 공정은 물질의 비율을 자유롭게 조절할 수 있고, 대기압의 조건에서도 공정이 가능하기 때문에 짧은 공정시간과 저비용의 장점이 있다. 제작된 소자는 p-type Si 위에 게이트 절연막으로 100 nm의 열산화막이 성장된 기판을 사용하였다. 표준 RCA 클리닝 후에 각 solution 물질을 spin coating 방식으로 증착하였다. 이후, photolithography, develop, wet etching의 과정을 거쳐 채널층 패턴을 형성하였다. 또한, 산화물 반도체의 전기적 특성을 향상시키기 위해서 후속 열처리 과정(post deposition annealing, PDA)은 필수적이다. CTA 방식은 높은 열처리 온도와 긴 열처리 시간의 단점이 있다. 따라서, 본 연구에서는 $100^{\circ}C$ 이하의 낮은 온도와 짧은 열처리 시간의 장점을 가지는 MWI (microwave irradiation)를 후속 열처리로 진행하였다. 그 결과, 각 물질로 구현된 소자들은 기존 a-IGZO와 비교하여 적은 양의 carrier suppressor로도 우수한 전기적 특성 및 안정성을 얻을 수 있었다. 따라서, Si, Hf, Zr 기반의 산화물 반도체는 기존의 Ga을 대체하여 저비용으로 디스플레이를 구현할 수 있는 IZO 기반 재료로 기대된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.208.2-208.2
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• 2015

최근 산화물 반도체에 대한 연구가 활발하게 이루어지고 있다. 비정질 산화물 반도체인 In-Ga-Zn-O(IGZO)는 기존의 비정질 실리콘에 비해 공정 단가가 낮으며 넓은 밴드 갭으로 인한 투명성을 가지고 있고, 저온 공정이 가능하여 다양한 기판에 적용이 가능하다. 반도체의 공정 과정에서 열처리는 소자의 특성 개선을 위해 필요하다. 일반적인 열처리 방법으로 furnace 열처리 방식이 주로 이용된다. 그러나 furnace 열처리는 시간이 오래 걸리며 일반적으로 고온에서 이루어지기 때문에 최근 연구되고 있는 유리나 플라스틱, 종이 기판을 이용한 소자의 경우 기판이 손상을 받는 단점이 있다. 이러한 단점들을 극복하기 위하여 저온 공정인 마이크로웨이브를 이용한 열처리 방식이 제안되었다. 마이크로웨이브 열처리 기술은 소자에 에너지를 직접적으로 전달하기 때문에 기존의 다른 열처리 방식들과 비교하여 에너지 전달 효율이 높다. 또한 짧은 공정 시간으로 공정 단가를 절감하고 대량생산이 가능한 장점을 가지고 있으며, 저온의 열처리로 기판의 손상이 없기 때문에 기판의 종류에 국한되지 않은 공정이 가능할 수 있을 것으로 기대된다. 따라서 본 연구에서는 마이크로웨이브 열처리가 소자의 전기적 특성 개선에 미치는 영향을 확인하였다. 제작된 IGZO 박막 트렌지스터는 p-type bulk silicon 위에 thermal SiO2 산화막이 100 nm 형성된 기판을 사용하였다. RCA 클리닝을 진행한 후 RF sputter를 사용하여 In-Ga-Zn-O (1:1:1) 을 70 nm 증착하였다. 이후에 Photo-lithography 공정을 통하여 active 영역을 형성하였고, 전기적 특성 평가가 용이한 junctionless 트랜지스터 구조로 제작하였다. 후속 열처리 방식으로 마이크로웨이브 열처리를 1000 W에서 2분간 실시하였다. 그리고 기존 열처리 방식과의 비교를 위해 furnace를 이용하여 N2 가스 분위기에서 $600^{\circ}C$의 온도로 30분 동안 열처리를 실시하였다. 그 결과, 마이크로웨이브 열처리를 한 소자의 경우 기존의 furnace 열처리 소자와 비교하여 우수한 전기적 특성을 나타내는 것을 확인하였다. 따라서 마이크로웨이브를 이용한 열처리 공정은 향후 저온 공정을 요구하는 소자 공정에 활용될 수 있을 것으로 기대된다.