열처리에 따른 Y₂O₃박막의 미세 구조 변화와 전기적 특성 변화에 대한 고찰

정윤하(Y. H. Jung),강성관(S. K. Kang),김은하(E. H. Kim),고대홍(D. H. Ko),조만호(M. H. Cho),황정남(C. N. Whang) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.3(1)

p-type Si (100) 기판 위에 습식 산화법으로 SiO₂ 층을 형성한 후, Ionized Cluster Beam(ICB) 증착 방법으로 200 Å 두께의 Y₂O₃ 박막을 증착 하였다. Y₂O₃ 박막이 증착 된 시편을 산소, 아르곤 분위기에서 열처리한 후, Atomic Force Microscopy(AFM)과 Transmission Electron Microscopy(TEM)을 사용하여 Y₂O₃ 박막의 표면과 계면을 관찰하였다. 열처리를 수행한 후 Y₂O₃ 박막과 Si 기판 사이에서 SiO₂층이 성장하고, 이트륨실리 케이트 층이 형성되는 것을 관찰할 수 있었다. 산소 분위기에서 열처리를 수행한 시편의 Y₂O₃ 박막 표면을 관찰한 결과, 표면 상부에 아르곤 분위기에서 열처리한 시편에서는 보이지 않았던 새로운 상이 형성되었음을 알 수 있었다. 또한 전기적 특성을 측정하기 위하여 Al/Y₂O₃/p-type Si (100) 의 캐패시턴스-전압 특성을 관찰하였고, 그 결과 Y₂O₃ 박막의 유전 상수 값이 약 9정도임을 알 수 있었다. We investigated the interfacial reactions between the Y₂O₃ film deposited by ICB processing and p-type (100) Si substrates upon annealing treatments in O₂ and Ar gas ambients. We also investigated the evolution of surface morphology of ICB deposited Y₂O₃ films upon annealing treatments. We observed that the root-mean-square (RMS) value of surface roughness measured by AFM increased with annealing time at 800℃ in O₂ ambient, while the change of surface roughness was not observed in Ar ambient. We also found the growth of SiO₂ layer and the formation of yttrium silicate layer. From the capacitance values (C_(acc)) measured by C-V measurements, the relative dielectric constant of Y₂O₃ film in metal-insulator-semiconductor (MIS) structure was estimated to be about 9.

Random Stability of an Additive-Quadratic-Quartic Functional Equation

Mohamadi, M.,Cho, Y. J.,Park, C.,Vetro, P.,Saadati, R. Hindawi Publishing Corporation 2010 Journal of inequalities and applications Vol.2010 No.1

<P>Using the fixed point method, we prove the generalized Hyers-Ulam stability of the following additive-quadratic-quartic functional equation f(x+2y)+f(x-2y)=2f(x+y)+2f(-x-y)+2f(x-y)+2f(y-x)-4f(-x)-2f(x)+f(2y)+f(-2y)-4f(y)-4f(-y) in complete random normed spaces.</P>

Effects of temperature on development, molting, and population growth of Yuukianura szeptyckii Deharveng & Weiner, 1984 (Collembola: Neanuridae)

Lee, Y.S.,Yang, N.H.,Son, J.,Kim, Y.,Park, K.H.,Cho, K. Elsevier Science B. V 2016 Applied soil ecology Vol.108 No.-

Neanuridae is one of the most diversified families of Collembola, but its biology and ecology are poorly understood. This is, to our knowledge, the first report on the biology of the neanurid species Yuukianura szeptyckii Deharveng & Weiner. Y. szeptyckii individuals were collected near a stream in Korea, and maintained on OECD artificial soil. This species showed a better reproductive performance on an artificial soil-based substrate than on charcoal-based substrate, and thus the soil-based substrate was used for investigating its biology. The sex ratio of Y. szeptyckii was found to be biased toward females (88.0%), and its mode of reproduction was sexual. The development, survival, longevity, reproduction, molting, and life table parameters of Y. szeptyckii were evaluated at 15, 20, 25, and 30<SUP>o</SUP>C. Individual growth was estimated by measuring head capsule widths. Mean developmental period from egg to adult decreased with increasing temperature from 73.7 d at 15<SUP>o</SUP>C to 25.6 d at 30<SUP>o</SUP>C. In the adult stage, ovipositional periods decreased with temperature from 273 d at 15<SUP>o</SUP>C to 45.5 d at 30<SUP>o</SUP>C, but senile periods increased at temperatures above 20<SUP>o</SUP>C. The developmental zero temperature was estimated to be 7.88<SUP>o</SUP>C. Median survival time (ST<SUB>50</SUB>s) and mean longevity decreased with temperature from 228d at 15<SUP>o</SUP>C to 98.0d at 30<SUP>o</SUP>C and from 401 d at 15<SUP>o</SUP>C to 177 d at 30<SUP>o</SUP>C, respectively. The maximum and minimum total number of eggs produced per individual were observed at 20<SUP>o</SUP>C (73.8 eggs) and 30<SUP>o</SUP>C (6.9 eggs), respectively. The head capsule width at first oviposition was significantly smaller at 25 and 30<SUP>o</SUP>C (0.30-0.31mm) than that at 15 and 20<SUP>o</SUP>C (0.45-0.46mm), while the head capsule width at last oviposition was smaller at 30<SUP>o</SUP>C (0.55mm) than that at 15 to 25<SUP>o</SUP>C (0.63-0.64mm). The molting rate (per individual per week) increased with temperature from 0.50 at 15<SUP>o</SUP>C to 1.43 at 30<SUP>o</SUP>C, but the total number of molts during the life span varied only slightly, ranging from 29.1 at 25<SUP>o</SUP>C to 33.2 at 30<SUP>o</SUP>C. The population reared at 20<SUP>o</SUP>C had the highest intrinsic rate of increase (0.060) and net reproductive rate (84.5), indicating that the optimal temperature for Y. szeptyckii population growth is 20<SUP>o</SUP>C. This study demonstrated that temperature can profoundly affect the development, molting, and population growth of Y. szeptyckii.

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.

Comment on 'Enhancement in hardness and transmittance of ZnS via SiO₂/Y₂O₃ multilayer'

Chung, Y.D.,Cho, D.H.,Kim, S.B.,Han, W.S. Elsevier Sequoia 2016 Journal of Alloys and Compounds Vol.664 No.-

In a recent paper [1], Huayu Zhang et al. reported data on the enhancement in hardness and transmittance of ZnS via SiO<SUB>2</SUB>/Y<SUB>2</SUB>O<SUB>3</SUB> multilayer. In particular, the authors discussed the chemical state of sputtered Y<SUB>2</SUB>O<SUB>3</SUB> on SiO<SUB>2</SUB>/ZnS measured by X-ray photoelectron spectroscopy. We suggested that the split spectrum of Y 3d doublet should be decomposed into the sum of the doublet and the exact notation of O 1s level should be applied. The O 1s of 528.8 eV could also be assigned to Y<SUB>2</SUB>O<SUB>3</SUB> and the O 1s of 531.5 eV could be assigned to Si related compound.

Hydrophobic Coating of Y2O3:Eu Phosphors by Using HMDSO/Toluene Plasma at Low Pressure and Their Wettability

Han S. Uhm,Kyung H. Lee,Soon C. Cho,Sung Y. Jo,Chan U. Bang,Dong K. Lee 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2

Surface treatments of Y2O3:Eu phosphors for improving the hydrophobic property were carried out using plasmas generated from a O-(Si(CH3)3)2 (HMDSO) in a low-pressure environment. The super-hydrophobic properties of the treated Y2O3:Eu phosphors were investigated. The samples treated by using the HMDSO/toluene glow plasma were analyzed by FTIR and OES and analyzed in terms of their contact angles (CAs). The effects of the HMDSO/toluene plasma treatments on the Y2O3:Eu phosphors were investigated in terms of the total surface free energy by using probe liquids to measure their contact angles (CAs). The total surface free energy of the Y2O3:Eu phosphors before and after a surface treatment with the HMDSO/toluene plasma, as estimated via the Owens-Wendt equation, was found to decrease from 82.2 mJ/m2 to 0.021 mJ/m2. This represents a significant improvement of the hydrophobicity of the Y2O3:Eu phosphors after the plasma treatment.

다운증후군의 산전진단을 위한 다양한 선별검사의 기여율 비교 - 산전 및 신생아때 진단된 96 례 분석 -

한정열(J . Y . Han),김문영(Y. M . Kim),조준형(J . H . Cho),안현경(H . K . Ahn),류현미(H . M . Ryu),김진미(J . M . Kim),김영미(Y . M . Kim),박소연(S . Y . Park),한혜경(H . K . Han),이영호(Y . H . Lee),양재혁(J . H . Yang) 대한산부인과학회 2000 Obstetrics & Gynecology Science Vol.43 No.10

연구의 목적은 다운증후군을 산전진단하기 위한 다양한 산전선별검사 (나이; 35세 이상, 임산부 혈청 marker를 이용한 triple test, 초음파; 비정상 소견, 후경부 투명대 (nuchal translucency), 후경부두께 (nuchal fold thickness))의 기여율를 비교하기 위한 것이다. 1990년 1월부터 1999년 9월까지 본원에서 산전 및 산후에 진단된 례는 총 96례 이었다. 산전 및 신생아기에 진단된 다운증후군의 빈도는 각각 68례 (71 %), 28례 (29 %)였다. 다운증후군 태아를 임신했던 임산부의 평균연령은 33±5.7세이다. 다운증후군의 1,000분만당 연도별 빈도율은 1990년부터 1999년까지 각각 0.4, 1.3, 0.7, 0.7, 1.6, 0.7, 1.2, 2.2, 2.0, 그리고 2.3 (Y=0.28±0.18 year, P=0.01)이었다. 산전진단된 다운증후군의 비율 (%)은 지난 10년간 각각 0 (0/2), 43 (3/7), 50 (2/4), 25 (1/4), 56 (5/9), 100 (5/5), 71 (5/7), 78 (14/18), 78 (14/18), 그리고 89 (17/19) (Y=12.9±8.9 year, P=0.000) 이었다. 다운증후군을 산전진단하기 위한 다양한 산전선별 검사에 따른 기여율은 35세이상의 연령에 의하면 30.2±5.6 %, triple test의 경우 18.2±3.4 %, 초음파에 의한 경우 51.7±6.3 % 이며, 초음파에 의한 산전 선별 검사가 통계적으로 유의하게 연령이나 triple test에 의한 경우 보다 다운증후군의 산전진단에 기여율이 높았다. (P=0.008) 결론적으로 본 연구에 의하면 지난 10년 동안 다운증후군을 산전 진단하기 위한 여러 선별 검사방법의 적용은 효율적이었으며, 특히 초음파에서 다양한 소견을 이용한 다운증후군의 산전선별검사는 연령이나 triple test 보다는 더욱더 의미가 있다고 추론된다. Objective : The purpose of this study was comparison of the contribution rate for prenatal diagnosis of Down syndrome using various screening methods (Age: greater than or equal to 35 years old, Serum markers: Triple test, Ultrasonography: abnormal sonographic findings, nuchal translucency, nuchal fold thickness).Methods : Total 96 cases of Down syndrome, prenatally or postnatally diagnosed between Jan. 1990 and Sept. 1999, made up the study population. We got the contribution rate of various prenatal screening methods of down syndrome, and obtained the efficiency of various screening program applied for last 10 years. Results : The frequencies of Down syndrome confirmed in prenatal and postnatal were 68 (71%) and 28 (29%) in respectively. The mean age of mother of Down syndrome fetus was 33.0±5.7 years old. The frequency rate of Down syndrome was 0.4, 1.3, 0.7, 0.7, 1.6, 0.7, 1.2, 2.2, 2.0 and 2.3 a 1,000 deliveries from 1990 to 1999 (Y= 0.28+0.18 year, P=0.01). The percentage of Down syndrome diagnosed prenatally was 0 (0/2), 43 (3/7), 50 (2/4), 25 (1/4), 56 (5/9), 100 (5/5), 71 (5/7), 78 (14/18), 78 (14/18) and 89 (17/19) from 1990 to 1999 (Y= 12.9+8.9 year, P=0.000). The contribution rate of prenatal diagnosis for Down syndrome was 30.2±5.6% by age, 18.2±3.4% by triple test and 51.7±6.3% by ultrasonography, and was significantly difference among each screen methods (P=0.008). Conclusions : This study shows that our prenatal screening program is highly effective to detect Down syndrome and especially ultrasonographic findings (abnormal sono findings, Nuchal translucency, Nuchal fold thickness) may be more important than that of age or Triple test to detect the Down syndrome prenatally.

작은빨간집모기(Culex tritaeniorhynchus)의 개체군 밀도와 일본뇌염환자 발생 예찰

심재철,윤영희,조양벽,이주연,신이현,양영철,박정은,이욱교,김정림,이원자 국립보건연구원 1994 국립보건원보 Vol.31 No.1

가족공동체를 떠난 간호대학생들의 대학생활체험

김고은,김유은,김희진,조유진,안주영,허다연,홍서우,차지영,박송이 이화여자대학교 간호학회 2018 이화간호학회지 Vol.- No.52

Purpose: The purpose of this study was to understand and explain the experiences of college life among junior nursing students who live apart from their families. Methods: 14 junior nursing students living apart from their families for at least one semester were recruited through snowballing and convenience sampling. Participants were interviewed individually using open ended questions. Data were collected from July to October in 2017 until data saturation. Interviews were transcribed verbatim and analyzed by using hermeneutic phenomenological method proposed by van Manen. Results: Five essential theme clusters emerged: (1) faced with diverse problems while living apart from family, (2) depend on family when stressed, (3) adapt to college life by being independent and forming self-initiative lifestyle, (4) confront with difficulties once again when adapting to academic curriculum restructured by practicum, (5) pave the way to nursing career and feel proud of overcoming the difficulties independently. Conclusion: Although most participants faced diverse problems in college life, they tried to adapt independently by forming self-initiative lifestyle and overturn the difficulties to positive experiences. In conclusion, the process of living apart from families transformed participants into proactive individuals. Adopting counseling programs could support starting their junior years successfully.

Enhanced photoluminescence due to Bi³⁺ → Eu³⁺ energy transfer and re-precipitation of RE doped homogeneous sized Y₂O₃ nanophosphors

Jadhav, A.P.,Thi Dinh, T.D.,Khan, S.,Lee, S.Y.,Park, J.K.,Park, S.W.,Oh, J.H.,Moon, B.K.,Jang, K.,Yi, S.S.,Kim, J.H.,Cho, S.H.,Jeong, J.H. Pergamon Press 2016 Materials research bulletin Vol.83 No.-

Precipitation and re-precipitation of metal ions has been carried out from original and supernatant solution producing Bi<SUP>3+</SUP> - Eu<SUP>3+</SUP> doped Y<SUB>2</SUB>O<SUB>3</SUB>:Eu<SUP>3+</SUP> and Eu<SUP>3+</SUP>/Tb<SUP>3+</SUP> doped Y<SUB>2</SUB>O<SUB>3</SUB>, respectively. Shorter reaction time is unable to consume all metal ions present in the solution which can be utilized through re-precipitation process. The doping of Bi<SUP>3+</SUP> - Eu<SUP>3+</SUP> in Y<SUB>2</SUB>O<SUB>3</SUB> helps to absorb maximum UV light. The activation of Y<SUB>2</SUB>O<SUB>3</SUB> matrix by Bi<SUP>3+</SUP> and Eu<SUP>3+</SUP> ions, together and separately, were studied considering the excitation energy transfer to the luminescence centers. The successful replacement of Y<SUP>3+</SUP> by RE<SUP>3+</SUP> ions can help for fine tuning of emission wavelength. Re-precipitation of supernatant solution by adding terbium precursor can successively produce uniform sized Tb<SUP>3+</SUP> doped Y<SUB>2</SUB>O<SUB>3</SUB>:Eu<SUP>3+</SUP>. The re-precipitation of the supernatant solution ensures maximum consumption of metal ions for higher product yield and possible fine tuning of emission wavelengths.