Effects of Ga contents on properties of CIGS thin films and solar cells fabricated by co-evaporation technique

Jung, S.,Ahn, S.,Yun, J.H.,Gwak, J.,Kim, D.,Yoon, K. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.4

This study examined the effects of Ga content in the CIGS absorber layer on the properties of the corresponding thin films and solar cells fabricated using a co-evaporation technique. The grain size of CIGS films decreased with increasing Ga content presumably because Ga diffusion during the 2nd stage of the co-evaporation process is more difficult than In diffusion. The main XRD peaks showed a noticeable shift to higher diffraction angles with increasing Ga content, which was attributed to Ga atoms substituting for In atoms in the chalcopyrite structure. Band gap energy and the net carrier concentration of CIGS films increased with Ga/(In+Ga) ratios. Regarding the solar cell parameters, the short circuit current density (J<SUB>SC</SUB>) decreased linearly with Ga/(In+Ga) ratios due to the lack of absorption in the long-wavelength portion of the spectrum, while the open circuit voltage (V<SUB>OC</SUB>) increase with those. However, V<SUB>OC</SUB> values at high Ga/(In+Ga) regions (>0.35) was far below than those extrapolated from the low Ga contents regions, finally resulting in an optimum Ga/(In+Ga) ratio of 0.28 where the solar cell showed the highest efficiency of 15.56% with V<SUB>OC</SUB>, J<SUB>SC</SUB> and FF of 0.625V, 35.03 mAcm<SUP>-2</SUP> and 0.71, respectively.

간호대생과 의대생의 간호사 이미지 비교

구민진,김수영,방정민,서아영,양희진,윤소람,이윤재,이재은,이지연,정윤경,최수정 이화여자대학교 간호과학대학 2014 이화간호학회지 Vol.- No.48

Purpose: This study aims to analyze the difference in the perception that nursing students and medical students have regarding the image of nurses. Method: The sampling group for this study was made up of 111 nursing students and 117 medicine students, conducted from the 19th August 2013 to 3rd September 2013. The tool used for this study is the “Nurse Image Scale”. The data is analyzed using the SPSS 21.0 program, technical stats, t-test and ANOVA with Scheffe test. Result: There was a notable difference in the results(t=6.94, p<001), with the average image perception score of nurses at 3.84±0.34 amongst nursing students being higher than the 3.50±0.38 amongst Medicine students. The average score of the 4 areas tested, “Qualification of a Nurse”, “Role of a Nurse”, “Social Participation of a Nurse” and “Interpersonal Skills of a Nurse” were all marked higher by the nursing students than the medicine students. The average score became notably higher as the period of practice became shorter with nursing students (F=4.21, p=.043). Furthermore, the average score for the “Qualification of a Nurse” was notably higher as the period of practice became shorter (F=3.98, p=.049). Medical students gave an average score for the “Qualification of a Nurse”(F=3.72, p=.027) and the “Interpersonal Skills of a Nurse”(F=4.11, p=.019) which was relative to the development of a nurse’s image, while the average score for the “Role of a Nurse” was notably higher with a longer period of practice(F=6.65, p=.011). Conclusion: The results of this study suggest that the image perception of a nurse can vary depending on the experience in period of practice. Therefore, together with this study conducted with nursing students and medicine students, there is a need for further studies conducted on image perception of nurses with various experience in period of practice.

서울지역 4년제 간호대학생들의 임상실습 유,무에 따른 진로태도성숙

권혜진,김보람,김소연,김수임,성정아,신영미,윤서진,이경진,홍영선,이자형,정덕유,신혜원 이화여자대학교 간호과학대학 2009 이화간호학회지 Vol.- No.43

This study was conducted to investigate the differences in the degrees of career attitude maturity according to the clinical practice experience of the college of nursing students. The convenience sample was 275 students attending the college of nursing in Seoul. Data was obtained through a questionnaire from December 1st to 12th, 2008. The instrument used to measure the career attitude maturity in this study was "A barometer of maturity in career attitudes" developed by Ki-hak, Lee(1997). The collected data were analyzed by descriptive statistics, Chronbach's alpha, t-test and ANOVA with the SPSS 16.0 program. Below is the result of this study. 1. The average score for career attitude maturity of nursing students who experienced clinical practices was 135.56(±12.17): higher than the average score of inexperienced students, 134.37(±12.44). However it could not show meaningful differences in the statistics(F=-.805, p=.422). 2. Determinacy, one of five subordinate concepts of career attitude maturity, was statistically significative. On average, the group comprised of students with clinical practices scored 27.60(±3.81): higher than that of unpracticed students, 26.63(±4.26)(F=-1.976, p=.049). 3. The more academic years they have, except for junior year students, the points of career attitude maturity relative to general characteristics were increasingly higher. The points were 132.60(±11.99) for freshmen, 135.93(±12.72) for sophomores, 133.50(±12.57) for juniors and 138.11(±11.24) for seniors(F=2.714, p=.045). 4. According to the age of the group, the grade of career attitude maturity became higher. The scores were 133.21(±12.34) for 18-19yrs., 134.05(±12.16) for 20-22yrs., 138.43(±10.96) for 23-26yrs. and 148.71(±12.76) for 27-32yrs. (F=5.118, p=.002). 5. The average total score for career attitude maturity of nursing students was 135.00(±12.30). Of the five subdivisions―readiness, conviction, determinacy, independence and finality― readiness demonstrated the highest result with 32.33(±4.46) followed by conviction, determinacy, independence and finality respectively. Based on the results, there are some proposals for further researches. As this research was only for college of nursing in Seoul, it is necessary to compare career attitude maturity with 3-year colleges and other departments. In addition, alongside clinical practices there is a growing need to develop programs that will not only provide guidelines but also prepare students for the maturity of their career attitude.

Characteristics of aerodynamic forces exerted on a twisted cylinder at a low Reynolds number of 100

Wei, D.J.,Yoon, H.S.,Jung, J.H. Pergamon Press ; Elsevier Science Ltd 2016 Computers & fluids Vol.136 No.-

Laminar flow over a twisted cylinder is numerically simulated at a Reynolds number of 100. The flow past a smooth cylinder is calculated for comparison. Jung and Yoon (J. Fluid Mech., 759, 2014) showed the considerable suppression of force coefficients at the subcritical Reynolds number of 3000. The present results verify that the twisted shape of the cylinder can be used to reduce the force coefficients at a low Reynolds number containing the laminar flow. This suppression of the force coefficients is supported by a longer vortex formation length produced by the twisted cylinder. We investigated the characteristics of the local force coefficients for a twisted cylinder. The simple periodic oscillation of the time histories of total and local lift coefficients for the twisted cylinder exhibits the same pattern as that of a smooth cylinder. However, the time history of drag for the twisted cylinder reveals the presence of multi-frequency oscillations, resulting in harmonic behavior of the power spectra. This is confirmed by a time sequence of the instantaneous flow fields during the half-period of the time histories of force coefficients. The nature of the three-dimensional (3-D) twisted shape forms the 3-D vortical structures along the spanwise direction, which leads to the harmonic behavior of the drag time trace power spectra.

Novel fabrication route for carbon-free and dense CuInSe₂ (CIS) thin films via a non-vacuum process for solar cell application

Eo, Y.J.,Lee, W.,Kim, K.,Ahn, S.,Cho, A.,Gwak, J.,Yoon, K.,Moon, S.Y.,Jung, H.R.,Kim, J.H.,Yun, J.H. Elsevier 2014 Current Applied Physics Vol.14 No.10

Carbon-free CuInSe<SUB>2</SUB> (CIS) thin film with a dense microstructure has been prepared using a novel non-vacuum based fabrication route. Cu<SUB>x</SUB>S<SUB>y</SUB> and In<SUB>2</SUB>Se<SUB>3</SUB> binary nanoparticles, approximately 10 nm in size, were synthesized by a low temperature colloidal process. The precursor film was deposited using the coating ink formulated with the binary nanoparticles and pyridine, and then annealed in the rapid thermal annealing (RTA) chamber at 540 <SUP>o</SUP>C for 15 min under selenium (Se) atmosphere. Scanning electron micrographs, X-ray diffraction patterns and Raman spectra showed a phase pure carbon-free and dense CIS thin film was prepared in this method. A solar cell device fabricated using this CIS thin film showed the following photovoltaic characteristics: V<SUB>OC</SUB> = 350 mV, J<SUB>SC</SUB> = 24.72 mA cm<SUP>-2</SUP>, FF = 38.73% and η = 3.36% under standard AM 1.5 condition.

Field-induced domain wall motion of amorphous [CoSiB/Pt]_N multilayers with perpendicular anisotropy

Choi, Y. H.,Lee, K. J.,Yoon, J. B.,Cho, J. H.,You, C.-Y.,Kim, T. W.,Jung, M. H. American Institute of Physics 2014 Journal of Applied Physics Vol.115 No.18

Amorphous CoSiB/Pt multilayer is a perpendicular magnetic anisotropy material to achieve high squareness, low coercivity, strong anisotropy, and smooth domain wall (DW) motion, because of the smoother interface compared with crystalline multilayers. For [CoSiB(6 angstrom)/Pt (14 angstrom)](N) multilayers with N = 3, 6, and 9, we studied the field-induced DW dynamics. The effective anisotropy constant K-1(eff) is 1.5 x 10(6) erg/cm(3) for all the N values, and the linear increment of coercive field H-c with N gives constant exchange coupling J. By analyzing the field dependence of DW images at room temperature, a clear creep motion with the exponent mu = 1/4 could be observed. Even though the pinning field H-dep slightly increases with N, the pinning potential energy U-c is constant (=35 k(B)T) for all the N values. These results imply that the amorphous [CoSiB/Pt](N) multilayers are inherently homogeneous compared to crystalline multilayers. For N <= 6, the pinning site density rho(pin) is less than 1000/mu m(2), which is about 1 pinning site per the typical device junction size of 30 x 30 nm(2). Also, the exchange stiffness constant A(ex) is obtained to be 0.48 x 10(-6) erg/cm, and the domain wall width is expected to be smaller than 5.5 nm. These results may be applicable for spin-transfer-torque magnetic random access memory and DW logic device applications. (C) 2014 AIP Publishing LLC.

유전질환 등록 시스템 운영 및 유전자 정보 Database 구축

정성철,김성수,이환석,윤경식,김규찬,정명호,오범석,이진성 국립보건연구원 1999 국립보건원보 Vol.36 No.-

다항식희귀분석을 이용한 기능성곡면의 모델링

윤상환,황종대,정윤교 한국공작기계학회 2002 한국공작기계학회 추계학술대회논문집 Vol.2002 No.-

This research presents modeling of a functional surface which is a constructed free-formed surface. The modeling introduced in this paper adopts polynomial regression that is utilizing approximating technique. The measured data are obtained from measuring with Coordinate Measuring Machine. This paper introduces efficient methods of Reverse Engineering using Polynomial Regression.

Clostridium속 세균포자의 안정성과 Plasmids 탐색

윤기홍,이정기,김병홍,소선주,전영숙,권기석,Z.G.Zeikus 한국산업미생물학회 1990 한국미생물·생명공학회지 Vol.18 No.2

제1, 2차세계대전 동안 분리되어 soil culture로 보존되어 온 131주의 Clostridium속 세균 중에서 100주가 재생되어 76%의 높은 재생력을 보여주었다. 이들 재생균주들의 발효산물을 분석한 결과, 주요산물이 acetone, ethanol 및 butanol인 solvent 생산균들은 63주이고 acetic acid와 butyric acid를 생성하는 산 생성균은 37주였다. 재생된 100주 중 plasmid를 갖는 strain은 50주로 plasmid 함유율은 50%였다. 균주에 따라서 하나에서 여러 개의 plasmids를 가지고 있었으며 그 크기는 1.0kb에서 50kb에 달하였다. Stock cultures of Clostridium, which had been maintained as spores with soil as carrier for 50-70 years, were used to determine their revival ratio, and plasmids were screened among the revived strains. From 131 soil cultures, 100 strains grew in the liguid medium giving the revival ratio of 76%. Analyses of the fermentation products divided the revived strains into 63 solventogenic strains and 37 acidogenic strains. Agarose gel electrophoresis showed one or more plasmid bands in the cleared lysates of 50 revived cultures. The sizes of the plasmids range in size from 1 to more than 50 kilobase pairs.

A Case of Radiation-Induced Pemphigus

Lee, M. S Korean Dermatological Association 1998 Annals of Dermatology Vol.10 No.3