• 제목/요약/키워드: Hetero-structure

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Compensation in VC and Word

  • Yun, Il-Sung
    • 말소리와 음성과학
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    • 제2권3호
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    • pp.81-89
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    • 2010
  • Korean and three other languages (English, Arabic, and Japanese) were compared with regard to the compensatory movements in a VC (Vowel and Consonant) sequence and word. For this, Korean data were collected from an experiment and the other languages' data from literature. All the test words of the languages had the same syllabic contexture, i.e., /CVCV(r)/, where C was an oral stop and intervocalic consonants were either bilabial or alveolar stops. The present study found that (1) Korean is most striking in the durational variations of segments (vowel and the following hetero-syllabic consonant); (2) unlike the three languages that show a constant sum of VC, Korean yields a three-way distinction in the length of VC according the type (lax unaspirated vs. tense unaspirated vs. tense aspirated) of the following stop consonant; (3) a durational constancy is maintained up to the word level in the three languages, but Korean word duration varies as a function of the feature tenseness of the intervocalic consonants; (4) consonant duration is proven to differentiate Korean the most from the other languages. It is suggested that the durational difference between a lax consonant and its tense cognate(s) and the degree of compensation between V and C are determined by the phonology in each language.

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고출력 AlGaAs SCH-SQW 레이저 다이오드 개발 (Development of High-Power AlGaAs SCH-SQW Laser Diode)

  • 손진승;계용찬;권오대
    • 전자공학회논문지A
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    • 제30A권10호
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    • pp.27-32
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    • 1993
  • Separate-confinement hetero-structure (SCH) broad area Laser Diodes (LD's) were fabricated from $Al_{0.07}$Ga$_{0.93}$/. As single-quantum-well (SQW) grown by metal organic chemical vapor deposition (MOCVD). Under pulsed operation, we obtained maximum output powers of about 0.8watt/facet and 1.83watt/facet from LD's with 60$\mu$m and 160$\mu$m channel width, respectively, without facet coatings. The differential quantum efficiency of the 60$\mu$m wide LD was about 21.7%/facet and its threshold current density was about 1k [A/cm$^{2}$]. The differential quantum efficiency of the 160$\mu$m wide LD was about 25.6%/facet and its threshold current density was about 1k[A/cm$^{2}$]. The minimum threshold current density of 60$\mu$m wide LD's was 620[A/cm$^{2}$] when the cavity length was 603$\mu$m and the minimum threshold current density of 160$\mu$m wide Ld's was 675[A/cm$^{2}$] when the cavity length was 752$\mu$m. The internal quantum efficienty and the internal loss of both LD's were 92.3% and 18.1cm$^{1}$, respectively.

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Transparent Conducting Multilayer Electrode (GTO/Ag/GTO) Prepared by Radio-Frequency Sputtering for Organic Photovoltaic's Cells

  • Pandey, Rina;Kim, Jung Hyuk;Hwang, Do Kyung;Choi, Won Kook
    • 센서학회지
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    • 제24권4호
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    • pp.219-223
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    • 2015
  • Indium free consisting of three alternating layers GTO/Ag/GTO has been fabricated by radio-frequency (RF) sputtering for the applications as transparent conducting electrodes and the structural, electrical and optical properties of the gallium tin oxide (GTO) films were carefully studied. The gallium tin oxide thin films deposited at room temperature are found to have an amorphous structure. Hall Effect measurements show a strong influence on the conductivity type where it changed from n-type to p-type at $700^{\circ}C$. GTO/Ag/GTO multilayer structured electrode with a few nm of Ag layer embedded is fabricated and show the optical transmittance of 86.48% in the visible range (${\lambda}$ = 380~770 nm) and quite low electrical resistivity of ${\sim}10^{-5}{\Omega}cm$. The resultant power conversion efficiency of 2.60% of the multilayer based OPV (GAG) is lower than that of the reference commercial ITO. GTO/Ag/GTO multilayer is a promising transparent conducting electrode material due to its low resistivity, high transmittance, low temperature deposition and low cost components.

Action Mechanism of Transfructosylation Catalyzed by Microbacterium laevaniformans Levansucrase

  • KIM, MIN-JEONG;PARK, HAE-EUN;SUNG, HEE-KYUNG;PARK, TACK-HYUN;CHA, JAE-HO
    • Journal of Microbiology and Biotechnology
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    • 제15권1호
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    • pp.99-104
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    • 2005
  • Microbacterium laevaniformans levansucrase synthesized various hetero-oligosaccharides by transferring fructosyl residue from sucrose to various saccharides as acceptors. The acceptor specificity test showed that reducing saccharides were more favorable acceptors than nonreducing saccharides. The transfructosylated product, fructosyl galactose, was produced in the presence of D-galactose as an acceptor. The chemical structure of the resulting fructosyl galactose was analyzed by yeast invertase and NMR, and identified as O-$\alpha$-D-galactosyl-(1${\to}$2)-$\beta$-D-fructofuranoside. These results indicate that the main transfructosylation activity of the enzyme is to make nonreducing transferred products via a transfer of fructosyl residue to acceptor molecules having reducing group. When nonreducing sugars, such as methyl $\alpha$-D-glucoside and methyl $\alpha$-D-galactoside, were used as an acceptor, the transfer product was also formed in spite of the reducing group blocked with methyl group. The fact that no transfer product was formed with sugar alcohols as acceptors was suggested to be due to marked conformational difference of acceptors.

Bi-directional Two Terminal Switching Device based on SiGe for Spin Transfer Torque (STT) MRAM

  • Yang, Hyung-Jun;Kil, Gyu-Hyun;Lee, Sung-Hyun;Song, Yun-Heub
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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    • pp.385-385
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    • 2012
  • A two terminal N+/P/N+ junction device to replace the conventional selective transistor was studied as a bilateral switching device for spin transfer torque (STT) MRAM based on 3D device simulation. An N+/P/N+ junction structure with $30{\times}30nm$ area requires bi-directional current flow enough to write a data by a drain induced barrier lowering (DIBL) under a reverse bias at N+/P (or P/N+ junction), and high current on/off ratio of 106. The SiGe materials are widely used in hetero-junction bipolar transistors, bipolar compensation metal-oxide semiconductors (BiCMOS) since the band gap of SiGe materials can be controlled by changing the fraction and the strain epilayers, and the drift mobility is increased with the increasing Ge content. In this work, N+/P/N+ SiGe material based junction provides that drive current is increased from 40 to $130{\mu}A$ by increased Ge content from 10~80%. When Ge content is about 20%, the drive current density of SiGe device substantially increased to 2~3 times better than Si-based junction device in case of 28 nm P length, which is sufficient current to operation of STT-MRAM.

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평균이동모형을 이용한 성장곡선모형의 이상점 진단에 관한 연구 (Outlier Detection in Growth Curve Model Using Mean-Shift Model)

  • 심규박
    • Journal of the Korean Data and Information Science Society
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    • 제10권2호
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    • pp.369-385
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    • 1999
  • 성장곡선모형에서 다중 이상값들이나 영향관측값들을 탐지하는 문제는 선형회귀모형에서의 문제에 비해 매우 복잡하여 거의 이루어지지 않고 있는 실정이다. 본 연구에서는 이상점을 포함하고 있는 성장곡선모형에서 이들을 탐지하는 방법으로 평균이동모형을 이용하는 방법을 소개하였다. 이 방법을 이용하여 찾아낸 자료가 이상점인지의 여부를 예측표본재이용 의사 베이즈 우도 기준법을 이용한 등분산성의 검정을 통해 알아보았다. 끝으로 Potthoff(1964)등이 사용한 자료를 이용한 예제를 통해 이상점 탐지와 등분 산성 검정을 실시한 결과를 제시하였다.

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박막의 조성비율에 따른 유기태양전지의 효율성 연구 (A Study about the Efficiency of Organic Photovoltaic Device as a function of the Material Concentration)

  • 김승주;이동근;박재형;공수철;김원기;류상욱
    • 반도체디스플레이기술학회지
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    • 제8권3호
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    • pp.1-5
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    • 2009
  • In this study, we have shown the power conversion efficiency of organic thin film photovoltaic devices utilizing a conjugated polymer/fullerene bulk-hetero junction structure. We use MDMO-PPV(Poly[2-methoxy-5-(3,7-dimethyloctyloxy -1,4-phenylenevinylene) as an electron donor, PCBM([6,6]-Phenyl C61 butyric acid methyl ester) as an electron accepter, and PEDOT:PSS used as a HTL(Hole Transport Layer). We have fabricated OPV(Organic Photovoltaic) devices as a function of the MDMO-PPV/PCBM concentration from 1:1 to 1:5. The electrical characteristics of the fabricated devices were investigated by means of I-V, P-V, F·F(Fill Factor) and PCE(power conversion efficiency). The power conversion efficiency was gradually increased until 1:4 ratio, also the highest efficiency of 0.4996% was obtained at the ratio.

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카울크로스빔용 PA/GF복합재료의 기계적 특성 분석에 관한 연구 (A Study on Mechanical Characteristics Analysamsarais of PA/GF Composite Materials for Cowl Cross Beam)

  • 김환국;박종빈;이지훈;정헌규
    • 한국염색가공학회지
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    • 제35권1호
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    • pp.29-41
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    • 2023
  • This study is about a hybrid lightweight cowl crossbeam structure with high rigidity and ability to absorb collision energy to support the cockpit module, which is an automobile interior part, and to absorb energy during a collision. It is a manufacturing process in which composite material bracket parts are inserted and injected into existing steel bars. When considering the mounting condition of a vehicle, the optimization of the fastening condition of the two parts and the mechanical properties of the composite material is acting as an important factor. Therefore, this study is about a composite material having a volume content of Polyamide(PA) and Glass Fiber used as a composite material for a composite material-metal hybrid cowl crossbeam. As a result of analyzing the physical properties of the PA/GF composite material, experimental data were obtained that can further enhance tensile strength and flexural strength by using PA66 rather than PA6 used as a base material for the composite material. And based on this, it contributed to securing the advantage of lightening by using high-stiffness composite material by improving the high disadvantage of the weight of the cowl crossbeam material, which was made only of existing metal materials.

Queering Narrative, Desire, and Body: Reading of Jeanette Winterson's Written on the Body as a Queer Text

  • Kim, Kwangsoon
    • 영어영문학
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    • 제56권6호
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    • pp.1281-1294
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    • 2010
  • In Written on the Body, by creating the narrator's ungendered and unsexed identity, Winterson makes her text open to the reader's assumption of the narrator's sexual and gender identity. Thus, this novel has been read, on the one hand, as a lesbian text by those who assume that the narrator is a female and, on the other hand, as a suspicious text colluding with patriarchal and heterosexual values by those who define the narrator as a male. Those readings of the narrator as one of either sex/gender, however, demonstrate how (academic as well as general) readers have been accustomed to the gender-based reading habits in which textual meanings are dichotomously arranged along the lines of sex and gender of characters. Challenging those dualistic "gendered" readings, this paper reads Winterson's Written on the Body as a queer text which interrogates, troubles, and subverts the heterosexual concepts of narrative, desire, and body without reducing the narrator's identity to the essentialist sex and gender system. More specifically, this paper examines how the narrator's 'un-/over-' determined sexual and gender identity queers the narrative structure of author-character-reader; how the narrator's queer (fluid) desire is passing and traveling across categorical contours of (homo-/hetero-) sexual desires; how Winterson challenges the concept of a coherent body and queers the concept of body as a hermeneutic text with myriad textual grids which are not coherently mapped by power but randomly inscribed by nomadic desires.

Rubrene:CuPc 정공 수송층이 도입된 p-i-n형 유기 박막 태양전지의 성능 특성 연구 (Performance Characteristics of p-i-n type Organic Thin-film Photovoltaic Cell with Rubrene:CuPc Hole Transport Layer)

  • 강학수;황종원;강용수;이혜현;최영선
    • Korean Chemical Engineering Research
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    • 제48권5호
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    • pp.654-659
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    • 2010
  • 박막형 유기 태양전지의 효율 향상을 위하여 정공 수송층인 CuPc 층에 p형 유기 반도체인 rubrene을 함량 별로 도핑하여 ITO/PEDOT:PSS/CuPc: rubrene/CuPc:C60(blending ratio 1:1)/C60/BCP/Al의 이종접합구조를 가지는 p-i-n형 유기 박막형 태양전지 소자를 제조한 후, 유기 태양전지의 전류 밀도-전압(J-V) 특성, 단락 전류($J_{sc}$), 개방 전압($V_{oc}$), 충진 인자(fill factor:FF), 에너지 전환 효율(${\eta}_e$) 등을 측정하고 계산하여 성능 평가를 수행 하였다. 정공 수송층으로 사용된 CuPc 층에 rubrene을 도핑함으로써 에너지 흡수 스펙트럼에서 흡수 강도가 감소하였다. 그러나 CuPc 보다 큰 밴드갭을 가지며 높은 정공 이동도를 가지는 결정성 rubrene의 도핑에 의해 제조된 p-i-n형 유기 박막 태양전지의 성능은 향상 되는 것으로 확인되었다. 제조된 유기 태양전지의 에너지 전환 효율(${\eta}_e$)은 1.41%로 실리콘 태양전지와 비교해서 아직도 성능 향상을 위한 많은 노력이 필요함을 보여 준다.