• Title/Summary/Keyword: V2C

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액체 내에 적용 가능한 바이오 플라즈마 소스 개발과 특성 연구

  • Im, Seung-Ju;Min, Bu-Gi;O, Hyeon-Ju;Lee, Jong-Yong;Gang, Seung-Eon;Choe, Eun-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.495-495
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    • 2013
  • 액체 내에 적용 가능한 바이오 플라즈마 소스를 제작하기 위해 텅스텐과 주사 바늘, 카테터 등의 여러 재료를 사용하여 시도를 해보았고 액체에서 방전이 일어날 수 있는 구조를 연구하였다. 전극 위에 절연체를 씌우고 그 위에 전극을 고정시켜 전압을 인가하여 전극 간에 표면방전을 통해서 플라즈마를 생성하는 방식을 사용하였다. 실험 장비는 AC 전압을 사용하였으며(12 kV, 22 kHz) 방전 전압과 방전 전류를 고전압 프로브(Tektronix P6015A)와 전류 프로브(P6021)를 사용하여 측정하였다. 모노크로미터를 이용하여 바이오 플라즈마 소스가 액체 속(수돗물, 증류수, 생리식염수)에서 방전 될 때 에미션 스펙트럼을 분석하여 산화질소(nitric oxide; NO), 과산화수소(hydrogen peroxide; H2O2), hydroxyl radical이 발생함을 확인하였다. 인체 내에서는 온도가 중요한 요소이기 때문에 액체에서 방전할 때 $40^{\circ}C$ 이하의 낮은 온도에서 이용이 가능하도록 연구하였다. 특히, 우리는 여러 종류의 액체(수돗물, 증류수, 생리식염수)에서의 방전 특성의 광학적 전기적 연구를 하였다.

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Wet Treatment를 이용한 Nonpolar InGaN/GaN Micro-Column LED Array 개발

  • Gong, Deuk-Jo;Bae, Si-Yeong;Kim, Gi-Yeong;Lee, Dong-Seon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.395-395
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    • 2013
  • GaN는 LED, 태양전지, 그리고 전자소자 등에 쓰이는 물질로, 관련 연구가 활발히 진행되고 있으며, 이와 더불어 top-down방식을 활용한 소자제작 방법 또한 발달되고 있다. 하지만, 일반적으로 LED 제작에 사용되는 c-plane GaN의 경우, c축 방향으로 발생하는 분극의 영향을 받게되며, 분극은 LED내 양자우물의 밴드를 기울게 하여 전자와 홀의 재결합률을 감소시켜 낮은 내부양자효율을 야기한다. 이러한 문제를 해결하기 위해 여러 가지 방법들이 제시되었으며, 그 중에서도 a면, 혹은 m면과 같은 nonpolar면을 사용하는 GaN LED가 주목받고 있다. 본 연구에서는, top-down방식을 통해 약 $2{\mu}m$ 크기의 diameter를 갖는 micro-sized column LED를 구현하였으며, 식각 후 드러나는 semipolar면을 wet treatment를 통해 제거하여 nonpolar면을 드러나게 하였으며, 이 면에 Ni/Au를 contact하여, 전기적, 광학적 특성을 논하였다. Fig. 1은 I-V 특성 그래프이며, Fig. 2는 EL측정 결과(광학적 특성)이다.

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Novel Fabrication of Platinum Counter Electrode in Dye-sensitized Solar Cells Using Nano-second Pulsed Laser Sintering

  • Lee, Jin Ah;Yoo, Kicheon;Kim, Woong;Ko, Min Jae
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.234-234
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    • 2013
  • The counter electrodes in dye-sensitized solar cells (DSSCs) play roles in not only collecting electrons from external circuit but also reducing I3- to I- in electrolytes. Generally, conventional counter electrodes for DSSCs are prepared from the high temperature treatment of the H2PtCl6 precursor solution at $400^{\circ}C$ However, the more simplified fabrication process of counter electrodes is required for the commercialization of DSSCs. In this work, we developed novel fabrication process of counter electrodes using nano-second pulsed laser. DSSCs employing counter electrodes prepared by laser process showed conversion efficiency of 6.75% with short-circuit current of 12.73 mA/cm2, open-circuit voltage of 0.74 V and fill factor of 0.72. Closer investigating of photovoltaic properties will be reported.

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Fractal Analysis of the Surface in Thin Film Capacitors

  • Hong, Kyung-Jin;Min, Yong-Ki;Cho, Jae-Cheol
    • KIEE International Transactions on Electrophysics and Applications
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    • v.11C no.2
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    • pp.18-22
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    • 2001
  • The thin films of high permitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)TiO$_3$ thin as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Sio$_2$/Si substrate at 4,000 [rpm] for 10 seconds. The structural characteristics of the surface were analyzed by fractal dimension. The thickness of BST ceramics thin films was about 260∼280 [nm]. The property of the leakage current was stable with 10-9∼10-11[A] when the applied voltage was 0∼3[V]. BST thin films ha low leakage current properties when fractal dimension was low and a coating area was high.

A Study on the Development of Thin Film Type Humidity Sensor Materials by Sol-Gel Method(II) (졸겔법에 의한 박막형 습도센서 소제개발에 관한 연구(II))

  • You, D.H.;Kang, D.H.;Na, D.K.;Hwang, M.W.;Yuk, J.H.;Lee, D.C.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1472-1474
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    • 1994
  • In this paper, $TiO_2-V_2O_5$ thin films are fabricated by Sol-Gel method and their humidity-sensing characteristics have been investigated. The microstructure of specimen is porous. The humidity-sensing characteristics of thin films are good according to increasing heat treatment temperature and decreasing measurement frequency.

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AN EXPERIMENTAL STUDY ON THE EFFECT OF ULTRASONIC INSTRUMENTATION ON THE ROOT CANAL OBTURATION (Ultrasonic Instrumentation이 근관충전에 미치는 영향에 관한 연구)

  • Hur, Soo-Beom;Hong, Chan-Ui
    • Restorative Dentistry and Endodontics
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    • v.16 no.1
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    • pp.181-189
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    • 1991
  • The purpose of this study was to evaluate the effect of apical seal produced by ultrasonic instrumentation. 120 extracted, permanent single rooted teeth were randomly divided into 6 groups of 20 teeth and root canals were enlarged & obturated according to Table I. After canal obturation, the obturated teeth were immersed in 2.5 % Methylene blue for 72 hrs. at $37^{\circ}C$ incubator and longitudinally sectioned. The apical sealing ability was evaluated by measuring the degree of dye penetration into the canal. The results were as follows: 1. All groups showed varying depth of dye penetration. 2. There were no significant differences between Group I and N, Group II and V, Group III and VI. (P>0.05) 3. Regardless of obturation method, there were no significant differences between hand instrumented group and ultrasonic instrumented group.(P>0.05).

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쌀 저장기간이 쌀 첨가 요구르트의 품질에 미치는 영향

  • 백지혜;고영태
    • Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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    • 2003.10a
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    • pp.216.2-216
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    • 2003
  • 본 연구에서는 우유에 탈지분유 또는 저장기간이 다른 3종의 통일벼(86년산, 88년산, 89년산)를 각각 2%(w/v)첨가하고 젖산균(Lacttobacillus 4종, Leuconostoc 1종)으로 발효하여 커드사으이 요구르트를 만든 후, 저장기잔이 다른 쌀의 첨가가 젖산균의 산생성과 커드상 요구르트의 품질(관능성, 점도, 저장성)에 미치는 영향을 조사하였다. TKf의 첨가로 젖산균의 산생성이 대조군(우유로만 만든 요구르트)보다 촉진되었는데, 젖산균의 종에 따라 다소 차이는 있으나 싸렝 의한 젖산균의 상생성 촉진효과는 쌀의 저장기간에 의하여 현저한 영향을 받지 않았다. 관능검사의 결과를 보면 우유에 첨가된 쌀은 저장기간이 다르더라도 요구르트의 관능성에 현저한 영향을 미치지 않았다. 점도측정의 결과를 보면 쌀의 저장기간이 경과할수록 쌀 첨가 요구르트의 첨도가 증가하였으며, 커드상 요구르트는 thixotropic fiow의 특성을 나타냈다. 5$^{\circ}C$에서 15일간 보존된 쌀 첨가요구르트의 저장성은 첨가된 쌀의 저장기간에 관계없이 우수하였다.

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MINIMAL CLOZ-COVERS OF κX

  • Jo, Yun Dong;Kim, ChangIl
    • Honam Mathematical Journal
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    • v.35 no.2
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    • pp.303-310
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    • 2013
  • In this paper, we first show that $z_{{\kappa}X}:E_{cc}({\kappa}X){\rightarrow}{\kappa}X$ is $z^{\sharp}$-irreducible and that if $\mathcal{G}(E_{cc}({\beta}X))$ is a base for closed sets in ${\beta}X$, then $E_{cc}({\kappa}X)$ is $C^*$-embedded in $E_{cc}({\beta}X)$, where ${\kappa}X$ is the extension of X such that $vX{\subseteq}{\kappa}X{\subseteq}{\beta}X$ and ${\kappa}X$ is weakly Lindel$\ddot{o}$f. Using these, we will show that if $\mathcal{G}({\beta}X)$ is a base for closed sets in ${\beta}X$ and for any weakly Lindel$\ddot{o}$f space Y with $X{\subseteq}Y{\subseteq}{\kappa}X$, ${\kappa}X=Y$, then $kE_{cc}(X)=E_{cc}({\kappa}X)$ if and only if ${\beta}E_{cc}(X)=E_{cc}({\beta}X)$.

Design of Multi-Band VCO with Fast AFC Technique (광대역 고속 AFC 기법을 적용한 다중 대역 VCO의 설계)

  • Ahn, Tae-Won;Yoon, Chan-Geun;Lee, Won-Seok;Moon, Yong
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.983-984
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    • 2006
  • Multi-band VCO with fast response adaptive frequency calibration (AFC) technique is designed in 1.8V $0.18{\mu}m$ CMOS process. The possible operation is verified for 5.8GHz band, 5.2GHz band, and 2.4GHz band using the switchable L-C resonators for 802.11a/b/g WLAN applications. To linearize its frequency-voltage gain, optimized multiple MOS varactor biasing technique is used. In order to operate in each band frequency range with reduced VCO gain, 4-bit digitally controlled switched-capacitor bank is used and a wide-range digital logic quadricorrelator is implemented for fast frequency detector.

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Synthesis and Characterization of the Thermally Stable Ho(hfa)3(tme)

  • Kang, Seong-Joo
    • Bulletin of the Korean Chemical Society
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    • v.25 no.8
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    • pp.1207-1210
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    • 2004
  • Holmium $\beta$ -diketonate complexes, Ho(hfa)$_3$(tme), has been prepared and characterized by IR, TGA, MS, and single-crystal X-ray analyses. This complex is air- and moisture-stable and most importantly has good volatility and thermal stability. Holmium atom binds to nine oxygen atoms, contributed by six oxygen atoms of three hfa ligands and three oxygen atoms of the tme ligand. The coordination polyhedron of Ho can be described as a distorted tricapped trigonal prism. Crystal data for $Ho(hfa)_3(tme)$; orthorhombic $P2_12_12_1$, a = 15.415(4), b = 13.17(2), c = 17.291(3) $\AA$, V = 3496(1) ${\AA}^3$.