Chalcogenization-Derived Band Gap Grading in Solution-Processed CuIn_<i>x</i>Ga_1–<i>x</i>(Se,S)₂ Thin-Film Solar Cells

Park, Se Jin,Jeon, Hyo Sang,Cho, Jin Woo,Hwang, Yun Jeong,Park, Kyung Su,Shim, Hyeong Seop,Song, Jae Kyu,Cho, Yunae,Kim, Dong-Wook,Kim, Jihyun,Min, Byoung Koun American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.49

<P>Significant enhancement of solution-processed CuInxGa1-x(Se,S)(2) (CIGSSe) thin-film solar cell performance was achieved by inducing a band gap gradient in the film thickness, which was triggered by the chalcogenization process. Specifically, after the preparation of an amorphous mixed oxide film of Cu, In, and Ga by a simple paste coating method chalcogenization under Se vapor, along with the flow of dilute H2S gas, resulted in the formation of CIGSSe films with graded composition distribution: S-rich top, In- and Se-rich middle, and Ga- and S-rich bottom. This uneven compositional distribution was confirmed to lead to a band gap gradient in the film, which may also be responsible for enhancement in the open circuit voltage and reduction in photocurrent loss, thus increasing the overall efficiency. The highest power conversion efficiency of 11.7% was achieved with J(sc) of 28.3 mA/cm(2), V-oc of 601 mV, and FF of 68.6%.</P>

포화수증기압 개념에 대한 예비 과학 교사들의 이해

정진우,박세진,김윤지 韓國敎員大學校 敎育硏究院 2009 敎員敎育 Vol.25 No.4

본 연구는 예비과학교사들이 포화수증기압 개념을 설명하는 과정에서 나타나는 이해를 밝히고자 하였다. 과학교육을 전공하는 여섯 명의 예비과학교사들을 대상으로 포화수증기압에 대한 설명을 요구하는 반구조화된 면담이 이루어졌다. 전사된 면담 내용과 비디오자료, 그리고 설명 과정에서 그려진 스케치 자료를 분석하여 참여자의 이해를 구조화하였다. 연구 결과, 예비과학교사가 대기 중의 물 개념을 설명하는 과정에서 다양한 이해가 표출되었다. 포화수증기압에 대한 이해로 분자운동론적 설명, 대기의 영향을 고려한 분자운동론적 설명, 기화압력을 이용한 설명, 확산 개념을 이용한 설명, 수증기의 공간을 한정시키는 설명이 나타났다. 예비과학교사들은 포화수증기압 개념에 대해 다양한 대안 개념을 가지고 있으며, 물의 상태 변화에 대한 분자운동론적 이해와 포화수증기압 개념을 통한 이해가 서로 연결되지 못하고 있음을 보여주었다. The purpose of this study is to analyze the understandings that represent that, in this course, the preservice science teachers have explained the concept of saturation vapor pressure. To do so, semi-structured interviews that requested students to explain saturation vapor pressure to six preservice science teachers were carried out. The preservice science teachers' understanding of the material was constructed by analyzing transcribed protocols, video tapes, and sketches that were drawn during the explanation. As a result of the research, a variety of understandings was discovered when the preservice science teachers explained the concept of atmospheric water. Understandings about saturation vapor pressure include the idea of molecular motion; the molecular motion model is considered to influence atmospheric pressure, the evaporation pressure model, the diffusion model and the limited space model. Preservice science teachers had alternative conceptions of saturation vapor pressure. The understanding of saturation vapor pressure and the understanding of the molecular motion model describing the change of water state are not connected.

Methexymethyl sulfide를 이용한 합성연구

김정순,고영관,김대광,윤세중 공주대학교 기초과학연구소 1992 論文集 Vol.30 No.1

For the preparation of broad range of substituted aryl derivatives from the bromophenyl methoxymethyl sulfide and the bromobenzyl methoxymethyl sulfide, various functional groups such as alkyl, ester and haloketone could be easily introduced in the aromatic methoxymethyl sulfides by treatment with various electrophiles. Substituted methoxymethyl phenyl sulfides were converted to the arenesulfonyl chlorides with chlorine in water-dichloromethane at 5∼10℃. And substituted benzyl methoxymethyl sulfides were also converted to the arylmethanesulfonyl chlorides with N-chlorosuccinimide in aqueous acetic acid, at 5∼10℃.

肉鷄飼育에 있어서 外國鷄種과 國內改良 交雜種과의 經濟性 分析

吳世正,尹熙燮 건국대학교 1980 學術誌 Vol.24 No.2

The experiment was conducted to compare economic performance at 8 weeks of age on 9 breeds. Three locally developed breeds were compared with three of existing imported breeds and three of newly imported breeds. Four hundred chicks of each breed was used in this experiment. The results obtained are as follows: 1.There was no significant difference in viability between local and imported broiler breeds. 2.High mortality was showed due to the Infection of staphylococosis and peritionitis which accounted for 40.3% of total occurrence. It was found that chicks of newly imported breeds were more resistant to these types of infections than other breeds. 3.Body weight at 8 weeks of age of local and, existing and newly imported breeds were 1676.93g, 1709.92g and 1755.69g. respectively. There was no difference in body weight gain among 3 groups during the first 4 weeks but difference was observed in body weight gain during 5-6 weeks of age between local and imported breeds. Therefore, it may be desirable to select the local broiler breeds on the basis of body weight at 6 weeks of age. 4.The feed requirement per 1 kg body weight gain of local and, existing and newly imported breeds were 2.59, 2.55 and 2.49, respectively. The feed conversion rate of newly imported breeds was superior to other breeds. 5.The highest net income at 8 weeks of age was obtained by newly imported breeds that rendered 402.26 Won per bird.

정맥주입 전문간호사가 삽입한 말초삽입형 중심정맥관(PICC) 사용 결과에 대한 후향적 분석

박정윤,박광옥,백미경,김세라,권혜리,양수진 대한기초간호자연과학회 2004 Journal of korean biological nursing science Vol.6 No.1

Background : Intravenous(Ⅳ) access is becoming an increasingly important part of health care today. The current drive for clinical effectiveness and cost-effective health care serves to increase the need for reliable vascular access. Venous access devices were developed to overcome problems associated with limited peripheral access and frequent venipuncture in patients with long-term therapy. Although the peripherally inserted central catheter(PICC) have become popular during recent years in USA, its procedure is rare in Korea. Purpose : The goal of this study was to analyze the PICC inserted patient data by Ⅳ CNS intervention. Method : A Total of 62 PICCs were inserted into 51 patients by the Ⅳ CNS during a 10-month period form November, 14, 2002, to October 2, 2W2. Data was obtained retrospectively through chart review. Result : The patient population included 34(54.8%) men and 28(45.2%) women, with a mean age 50.6 years. The main indication for PICC placement was to access vein in poor peripheral venous status(40.3%). The mean served interval for PICC insertions was 16.7 days(range, 2~61 days). The reasons for removal were completed therapy in 18 cases(29.0%), patient death in 13 cases(21.0%), and mechanical or functional PICC problem in 10cases(16.1%). The three PICCs removed for presumed infection, and one had only positive tip cultures(0.2%). Conclusion : PICCs are rapidly growing popularity and required an extended course of Ⅳ therapy.

소목(Caesalpinia sappan) 추출물의 Streptococcus mutans에 대한 성장, 산생성, 부착 및 비수용성 글루칸 합성 억제에 미치는 영향

유용욱,유현희,김윤정,유미선,서세정,이황,이흥수 대한구강보건학회 2003 大韓口腔保健學會誌 Vol.27 No.2

Streptococcus mutans is known as the causative bacterial playing the most important role in forming plaque and it is being noticed as major causative bacteria of dental caries. Therefore, development of more effective, substantial and safe preventive agent against dental caries and periodontal disease is honestly required. The present study was designed to investigate the effect of chloroform extract(CE), n-butanol extract(BE),methanol extract(ME) and water extract(WE) of Caesalpinia on the growth, acid production, adhesion, and insoluble glucan synthesis of Streptococcus mutans. The CE, BE, ME and WE decreased the growth and acid production of S.mutans than that of control, especially, the ME was more effective than other extracts. The effect of CE, BE, ME and WE on the adherences to saliva-coated hydroxyapatite bead(S-HA) were evaluated. At the concentration of 2,000 ㎍/㎖, the CE showed 32% rate of bacterial adherence to S-HA, whereas, other extracts of the same concentration producedgreater than 50% rate. The CE and BE were significantly decreased the reduction rates of water insoluble glucan formation from sucrose by crude glucosyltransferase of S.mutans. Thus, the application of C. sappan can be considered a useful and a practical method for the prevention of dental caries.

마우스에서 고려홍삼 추출물의 단회 및 반복투여독성 평가

임숙희, 신선희, 장자영, 변상국, 이예은, 박동선, 전정희, 이용경, 이동만, 이세라, 김재승, 황방연, 노재섭, 남상윤, 윤영원, 김윤배 충북대학교 동물의학연구소 2005 Journal of Biomedical and Translational Research Vol.6 No.2

본문참조

Controlled synthesis of (hk1) preferentially oriented Sb2Se3 rod arrays by co-evaporation for photovoltaic applications

Park, Si-Nae,Kim, Se-Yun,Lee, Sang-Ju,Sung, Shi-Joon,Yang, Kee-Jeong,Kang, Jin-Kyu,Kim, Dae-Hwan Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.45

<P>In this paper, we propose that the microstructural control of (<I>hk</I>1) preferentially oriented Sb2Se3 films from flat films to rod arrays can improve their photovoltaic efficiency by maximizing the carrier transport characteristics. We found that, during co-evaporation, there is a narrow substrate temperature window where the Sb2Se3 rod array can be formed with an (<I>hk</I>1) preferred orientation, thus maximizing the carrier transport characteristics. The substrate-temperature-dependent morphology of the Sb2Se3 films can be explained by nucleation and growth theory and the terrace-ledge-kink model. Dramatic changes in the (<I>hk</I>0) and (<I>hk</I>1) texture coefficients occur at 315 °C, and the critical temperature for obtaining the (<I>hk</I>1) preferentially oriented Sb2Se3 film is a substrate temperature of 315 °C. On the basis of the observed variation in the film microstructure and texture coefficient, the optimum Sb2Se3 rod array having an (<I>hk</I>1) preferred orientation is formed in a narrow range of substrate temperatures. As a result, we obtained an optimized Sb2Se3 thin-film rod array that shows effective carrier transportation. Further, the optimum fill factor, short circuit current, open circuit voltage, and efficiency of the Sb2Se3 device were observed in the Sb2Se3 rod array having an (<I>hk</I>1) preferred orientation, and the enhanced carrier transport characteristics are the main reason for the improved device properties. These results show that controlling the microstructure of Sb2Se3 allows improvements in the efficiency of (<I>hk</I>1) preferentially oriented Sb2Se3 films.</P>

Sb-Se-based phase-change memory device with lower power and higher speed operations

Yoon, Sung-Min,Lee, Nam-Yeal,Ryu, Sang-Ouk,Choi, Kyu-Jeong,Park, Y.-S.,Lee, Seung-Yun,Yu, Byoung-Gon,Kang, Myung-Jin,Choi, Se-Young,Wuttig, M. IEEE 2006 IEEE electron device letters Vol.27 No.6

A phase-change material of Sb<SUB>65</SUB>Se<SUB>35</SUB> was newly proposed for the nonvolatile memory applications. The fabricated phase-change memory device using Sb<SUB>65</SUB>Se<SUB>35</SUB> showed a good electrical threshold switching characteristic in the dc current-voltage (I-V) measurement. The programming time for set operation of the memory device decreased from 1 μs to 250 ns when Sb<SUB>65</SUB>Se<SUB>35</SUB> was introduced in place of the conventionally employed Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> (GST). The reset current of Sb<SUB>65</SUB>Se<SUB>35</SUB> device also dramatically reduced from 15 mA to 1.6 mA, compared with that of GST device. These results are attributed to the low melting temperature and high crystallization speed of Sb<SUB>65</SUB>Se<SUB>35</SUB> and will contribute to lower power and higher speed operations of a phase-change nonvolatile memory.

Synthesis of the solution-processed wide band-gap chalcopyrite CuGa(S,Se)₂ thin film and its application to photovoltaics

Park, Gi Soon,Park, Se Jin,Jeong, Jae Seung,Chu, Van Ben,Hwang, Yun Jeong,Min, Byoung Koun Elsevier 2017 THIN SOLID FILMS - Vol.621 No.-

<P><B>Abstract</B></P> <P>A wide band-gap chalcopyrite CuGa(S,Se)<SUB>2</SUB> (CGSSe) thin film was synthesized via the simple solution based method of precursor solution coating and subsequent heat treatment processes. Various characterizations such as X-ray diffraction, UV–vis–NIR spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Hall measurement, and dynamic secondary ion mass spectroscopy revealed a successful formation of the wide band-gap polycrystalline chalcopyrite film with nearly the same amounts of S and Se elements. The synthesized CGSSe film was applied as an absorber layer to the conventional thin film solar cell construction, which yielded an open circuit voltage (<I>V</I> <SUB> <I>oc</I> </SUB>) of 0.52V, a short circuit current density (<I>J</I> <SUB> <I>sc</I> </SUB>) of 3.5mA·cm<SUP>−2</SUP>, and an overall power conversion efficiency (<I>PCE</I>) of 1.0%. The photovoltage was lower than the expected value implying that there is a large voltage loss relative to the wide band-gap (~2.11eV). It would be attributable to improper combination of the CGSSe absorber film and the CdS buffer layer in the conventional cell architecture, which may promote interface recombination due to an absence of a “spike” band alignment (i.e. conduction band offsets are slight positive values, 0.1eV<Δ<I>E</I> <SUB> <I>c</I> </SUB> <0.4eV) with the CGSSe absorber layer. Moreover, improvements in morphologies, such as enlarged grains and reduced pore sizes, need to be achieved for higher solar cell efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Wide band-gap CuGa(S,Se)<SUB>2</SUB> thin films were well synthesized via solution process. </LI> <LI> The film was applied as an absorber layer to thin film solar cell architecture. </LI> <LI> Formations of ‘spike’ band structures and morphology enhancements are required. </LI> </UL> </P>