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RISS 인기검색어
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- 저자 : 김영국(Y G Kim) (검색결과 66 건)
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F-free Y & Cu 전구용액 적용에 의한 YBCO coated conductors의 MOD 공정 개선
김영국,유재무,정국채,고재웅,조윤숙,허은옥,Kim, Y.K.,Yoo, J.M.,Chung, K.C.,Ko, J.W.,Cho, Y.S.,Heo, E.O. 한국초전도학회 2006 Progress in superconductivity Vol.8 No.1
Total Fluorine content in the precursor solution for MOD processing of YBCO coated conductors can be significantly reduced by synthesizing precursor solution with F-free Y & Cu precursor and Barium trifluoroacetate(TFA). It was shown that crack-free and uniform precursor films were formed after calcinations in humidified oxygen atmosphere. Less than 2 hours are required to finish the calcination process, and XRD measurement shows that $BaF_2,\;CuO,\;and\;Y_2O_3$ are major constituent of calcined precursor films. Film thickness after calcination was measured to be ${\sim}2.8$ um by applying slot-die coating method. In particular, addition of Samarium shows critical current of Ic=226 A/cm-w($Jc=3.4\;MA/cm^2$). Also discussed are recent developments in the reel-to-reel processing using F-free Y & Cu precursor solutions. It is shown that uniform and fast processing route to YBCO coated conductor with high Ic can be provided by employing F-free Y & Cu precursor solutions in MOD process.
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김영국,송병관,이정구,백연경,Kim, Y.K.,Song, B.K.,Lee, J.G.,Baek, Y.K. 한국분말야금학회 2020 한국분말재료학회지 (KPMI) Vol.27 No.2
Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.
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화학적으로 변형된 전구용액을 이용한 YBCO 박막 제조
김영국,유재무,정국채,고재웅,김영준,한봉수,Kim, Y.K.,Yoo, J.M.,Chung, K.C.,Ko, J.W.,Kim, Y.J.,Han, B.S. 한국초전도학회 2006 Progress in superconductivity Vol.7 No.2
Superconducting YBCO films were successfully fabricated by MOD process using chemically modified precursor solution. In this study, a chemically modified precursor solution for MOD processing was synthesized using metal-organic salts and organic additives. It was shown that crack-free and uniform precursor films were formed after calcination in humidified Oxygen atmosphere. Less than 3 hours are required to finish the calcination process. XRD measurement shows that $BaF_2,\;CuO,\;Y_2O_3$ are major constituent of precursor films. Furthermore, YBCO films without any secondary phases were successfully fabricated after annealing in wet $Ar/O_2$ atmosphere. The YBCO film prepared on a $LaAlO_3$ single crystal substrate ($10mm{\times}10mm$) gives transport $I_c$ of 10A at 77K. This chemical modification approach is a possible candidate for improving MOD-processing of YBCO coated conductor.
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IBAD 기판을 적용한 산화물 전구체 MOD 공정에 의한 YBCO Coated Conductor의 제조
김영국,유재무,고재웅,허순영,홍계원,이희균,정형식,Kim Y. K.,Yoo J. M.,Ko J. W.,Heo S. Y.,Hong G. W.,Lee H. G.,Chung H. S. 한국초전도학회 2005 Progress in superconductivity Vol.6 No.2
YBCO coated conductors have been fabricated with a newly developed oxide-precursor-based MOD process. The precursor solution was synthesized with low cost YBCO powders as starting materials and YBCO coated conductors have been deposited on IBAD substrate ($CeO_2$/IBAD-YSZ/SS). YBCO coated conductor prepared by dip coating shows transport $I_c$ of 15A/cm-w at 77 K. Microstructural and crystallographic analyses indicate that YBCO layer was grown in epitaxy with substrate and exhibited well-developed dense microstructure. Also discussed are processing and analysis of YBCO coated conductor by slot-die web coating method. It was shown that this oxide-based MOD process provides a low cost route to coated conductor with high $J_c$.
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김영국,윤문철,하만경,심성보,Kim, Y.K.,Yoon, M.C.,Ha, M.K.,Sim, S.B. 한국기계가공학회 2002 한국기계가공학회지 Vol.1 No.1
In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive least square method (RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, The stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.
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김영국,노정구 ( Y . K . Kim,J . K . Roh ) 한국축산학회 1986 한국축산학회지 Vol.28 No.2
Twenty corn samples from feed companies and farms were analyzed for zearlenone. Zearalenone was determined by using a high pressure liquid chromatography (HPLC) with Micropak MCH-10 column and methanol-water system and with an ultraviolet detector set at 274 ㎚. Zearalenone was detected in 8 samples at the level of 0.2-3 ㎎/Kg. And 2 samples contained more than 1 ㎎/Kg.
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홍수영 ( S Y Hong ),이기연 ( K Y Lee ),정혜정 ( H J Jung ),김희연 ( H Y Kim ),허남기 ( N K Hoe ),안영섭 ( Y S Ahn ),김영국 ( Y G Kim ),이정훈 ( J H Lee ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2013 강원 농업생명환경연구 Vol.25 No.3
참당귀와 가시오갈피 꽃 생체와 수증기증류법과 SDE 추출법으로 추출된 정유의 휘발성 화합물을 SPMEGC-MS로 분석하여 비교·동정하였다. 참당귀 꽃을 수증기증류법과 SDE 추출법으로 추출한 정유의 추출 수율은 각각 0.063%과 0.044%이었고, SPME-GC-MS 분석시 휘발성 화합물은 23종과 26종이 검출되었으며, 생체 시료에 함유되어 있는 휘발성 화합물은 37종이 검출되었다. 생체 시료의 주요 휘발성 화합물은 α-pinene (16.51%), β-phellandrene (14.75%), cubebene (11.25%), β-myrcene(7.36%), nonane (7.25%)이었다. 수증기증류법으로 추출한 정유의 주요 화합물은 guaiol (23.99%), α-elemene(19.34%), α-cubebene (12.51%), α-farnesene (5.63%), caryophyllene (5.59%)이었으며, SDE 추출법으로 추출한 정유의 주요 화합물은 guaiol (42.24%), butylated hydroxytoluene (17.98%), ledol (5.84%), cyclotetradecane(5.30%), τ-cadinol (5.20%)이었다. 생체 시료와 추출방법별 정유의 휘발성 화합물 구성을 비교해보면, 생체시료의 hydrocarbon류의 함량은 97.93%였으나, 수증기증류법과 SDE 추출법으로 추출된 정유의 hydrocarbon류 함량은 각각 61.20%와 27.42%로 감소하였고, alcohol류는 37.69%와 69.36%로 증가하였다. 가시오갈피 꽃을 수증기증류법과 SDE 추출법을 이용하여 추출한 정유의 추출 수율은 각각 0.105%과 0.094%이었고, SPME-GC-MS 분석시 휘발성 화합물은 각각 32종과 38종이 검출되었으며, 생체 시료에 함유되어 있는 휘발성 화합물은 19종이 검출되었다. 생체 시료의 주요 휘발성 화합은 trans-α-bergamotene (31.46%), α-phellandrene (24.29%), cedrene (11.86%), d-limonene(8.68%), caryophyllene (6.33%), α-pinene (3.51%), α-farnesene (3.16%), o-cymene (2.99%), β-bisabolene (1.64%)이었다. 수증기증류법으로 추출된 정유의 주요 휘발성 화합물은 d-limonene (29.67%), limonene (25.64%) α-myrcene(16.22%), α-pinene (7.12%), α-elemene (4.24%), β-phellandrene (2.89%), 1R-α-pinene (2.56%), caryophyllene(2.16%), 3-carene (1.69%), α-curcumene (1.04%)이었으며 SDE 추출법으로 추출된 정유에서 검출된 주요 화합물은 α-elemene (20.56%), caryophyllene (20.42%) (-)-spathulenol(12.85%), d-limonene (9.88%), α-curcumene (6.31%), caryophyllene oxide (6.00%), α-myrcene (2.88%), cedrene(2.78%), α-farnesene (2.42%), β-bisabolene (1.91%)이었다. 생체 시료와 추출방법별 정유의 휘발성 화합물 구성을 비교해보면, 생체시료는 hydrocarbon류의 함량이 99.62%로 대부분을 차지했으나, 수증기증류법으로 추출한 정유의 hydrocarbon류의 함량은 96.90%, SDE 추출법으로 추출된 정유의 hydrocarbon류의 함량은 76.04%로 생체 시료보다 hydrocarbon류의 함량이 감소한 반면 alcohol류와 ether류가 증가하였다. Volatile flavor compounds were obtained from fresh and essential oils of Angelica gigas Nakai flower and Ancanthopanax senticosus flower by hydrodistillation extraction (HE) and simultaneous steam distillation and extraction apparatus (SDE), samples were collected by solid phase microextraction (SPME) methods, and the compositions of the samples were analyzed by gas chromatograpy-mass spectrometry (GC-MS). Thirty seven constituents were identified from fresh flower of Angelica gigas Nakai. Major constituents were α-pinene (16.51%), β-phellandrene (14.75%), cubebene (11.25%), β-myrcene (7.36%) and nonane (7.25%). By HE extraction, twenty three were identified from essential oils in the flower part of Angelica gigas Nakai. Major constituents were guaiol (23.99%), α-elemene (19.34%), α-cubebene (12.51%), α-farnesene (5.63%) and caryophyllene (5.59%). By SDE extraction, twenty six were identified from essential oils in the flower part of Angelica gigas Nakai. Major constituents were guaiol (42.24%), butylated hydroxytoluene (17.98%), ledol (5.84%), cyclotetradecane (5.30%) and τ-cadinol (5.20%). Nineteen constituents were identified from fresh flower of Ancanthopanax senticosus. Major constituents were trans-α-bergamotene (31.46%), α-phellandrene (24.29%), cedrene (11.86%), d-limonene (8.68%), caryophyllene (6.33%), α-pinene (3.51%), α-farnesene (3.16%), o-cymene (2.99%) and β-bisabolene (1.64%). By HE extraction, thirty two were identified from essential oils in the flower part of Ancanthopanax senticosus. Major constituents were d-limonene (29.67%), limonene (25.64%) α-myrcene (16.22%), α-pinene (7.12%), α-elemene (4.24%), β-phellandrene (2.89%), 1R-α-pinene (2.56%), caryophyllene (2.16%), 3-carene (1.69%) and α-curcumene (1.04%). By SDE extraction, thirty eight were identified from essential oils in the flower part of Ancanthopanax senticosus. Major constituents were α-elemene (20.56%), caryophyllene (20.42%) (-)-spathulenol (12.85%), d-limonene (9.88%), α-curcumene (6.31%), caryophyllene oxide (6.00%), α-myrcene (2.88%), cedrene (2.78%), α -farnesene (2.42%) and β-bisabolene.
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