• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.259-259
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• 2011

염료감응형 태양전지(Dye-Sensitized Solar Cells:DSSC)는 환경 친화적이며, 저가의 공정에 대한 가능성으로 기존의 고가의 결정질 실리콘 태양전지의 경제적인 대안으로 각광을 받고 있다. 최근 염료감응형 태양전지는 투명 전도성 산화막(Transparent Conducting Oxide : TCO)으로 사용되는 Fluorine Tin Oxide (FTO)가 증착된 유리기판 위에 주로 제작된다. FTO는 낮은 비저항과 가시광선 영역에서 높은 투과도를 가지는 우수한 전기-광학적 특성을 갖지만, 비교적 공정이 까다로운 Chemical Vapor Deposition (CVD)법으로 제조하며, 전체 공정비용의 60%를 차지하는 높은 생산단가로 인해 현재 FTO를 대체할 재료개발 연구가 활발히 진행되고 있다. 그 중 ZnO (Zinc Oxide)는 우수한 전기-광학적 특성과 비교적 저렴한 가격으로 새로운 TCO로써 주목받고 있다. ZnO는 넓은 energy band gap (3.4 [eV])의 육방정계 울자이트(hexagonal wurtzite) 결정 구조를 가지는II-VI족 n형 반도체 물질이며, III족 금속원소인 Al, Ga 및 In 등의 불순물을 첨가하면 TCO로서 우수한 전기-광학적 특성과 안정성을 나타낸다. 이들 물질중 $Zn^{2+}$ (0.060 nm)의 이온반경과 유사한 $Ga^{2+}$0.062 nm) 이온이 ZnO의 격자반경을 최소화 시킬 수 있다는 장점으로 최근 주목 받고 있다. 하지만 Ga-doped ZnO (GZO)의 경우 DSC에 사용되는 루테늄 계열의 산성 염료 하에 장시간 두면 표면이 파괴되는 문제가 발생하며, $TiO_2$ paste를 Printing 후 열처리하는 과정에서도 박막의 파괴가 발생할 수 있다. 이를 방지하기 위해 $TiO_2$ Blocking Layer를 GZO 투명전극 위에 증착하였다. 또한, $TiO_2$ Blocking Layer를 적용한 GZO 박막을 전면전극으로 이용하여 DSC를 제작하여 효율을 확인하였다. 2wt%의 $Ga_2O_3$가 도핑된 ZnO 박막은 20mTorr 400$^{\circ}C$에서 Pulsed Laser Deposition (PLD)에 의해 성장되었고, $TiO_2$박막은 Ti 금속을 타겟으로 이용하여 30mTorr 400$^{\circ}C$에서 증착되었다. Scanning electron microscopy (FE-SEM)을 이용한 박막 분석 결과 $TiO_2$가 증착된 GZO 박막의 경우 표면 파괴가 일어나지 않았다. Solar Simulator을 이용하여 I-V특성 측정결과 상용 FTO를 사용한 DSC 수준의 효율을 나타내었다. 이에 따라 Pulsed Laser Deposition을 이용해 제작된 GZO 기판은 $TiO_2$ Blocking Layer를 이용하여 표면 파괴를 방지할 수 있었으며, 이는 향후 염료감응형 태양전지의 투명전극에 적용 가능 할 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2289-2294
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• 2021

In the present study, an original spark plasma sintering-reactive synthesis (SPS-RS) method for minerallike ceramic materials based on SrAl₂Si₂O₈ feldspar-like skeleton structure was used for the first time, promising solid-state matrices for reliable immobilization of high-energy ⁹⁰Sr. The method is based on the "in-situ" reaction of a mixture of SrO, Al₂O₃ and SiO₂ oxides when heated by a unipolar pulsed current under compacting pressure. The phase and elemental composition structure were studied. The dynamics of the consolidation of the reaction mixture of oxides was studied in the range of 900-1200 ℃. The study found the temperature of the high-speed (minutes) SPS-RS formation of single-phase SrAl₂Si₂O₈ composition ceramic in the absence of intermediate reaction products with a relative density of up to 99.2% and compressive strength up to 145 MPa and a strontium leaching rate of 10^-4g/cm²·day.

• 한국분말재료학회지
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• 제18권2호
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• pp.105-111
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• 2011

This study investigated the effect of wire diameter and applied voltage on the fabrication of Ni-free Fe-based alloy nano powders by employing the PWE (pulsed wire evaporation) in liquid, for high temperature oxidation-resistant metallic porous body for high temperature particulate matter (or soot) filter system. Three different diameter (0.1, 0.2, and 0.3 mm) of alloy wire and various applied voltages from 0.5 to 3.0 kV were main variables in PWE process, while X-ray diffraction (XRD), field emission scanning microscope (FE-SEM), and transmission electron microscope (TEM) were used to investigate the characteristics of the Fe-Cr-Al nano powders. It was controlled the number of explosion events, since evaporated and condensed nano-particles were coalesced to micron-sized secondary particles, when exceeded to the specific number of explosion events, which were not suitable for metallic porous body preparation. As the diameter of alloy wire increased, the voltage for electrical explosion increased and the size of primary particle decreased.

• 한국환경보건학회지
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• 제30권1호
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• pp.15-21
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• 2004

In an attempt to analyze the characteristics of domestic pathogenic strains of S. pneumoniae, the basic epidemiological charactristics of pathogenic strains such as their serotypes and frequency of penicillin resistance, and pattern of chromosomal DNA from PFGE(pulsed-field gel electrophoresis) were observed. For this study,56 strains of S. pneumoniae isolated from inpatients and outpatients in the four domestic university hospitals were collected from January to December in 1998. Among those strains, a total of 56 pathogenic strains from blood(39 isolates), cerebrospinal fluid(8 isolates) and other specimen(9 isolates) were selected and isolated. The penicillin resistance frequency of those 56 strains was identified with disk diffusion method with 66.1％. From the invasive strains, predominant serotypes were isolated in the order of 19F(12.5％), 23F(10.7%), 14(10.7%) and 9V(10.7％), totalling 45 percent. This experiment also used PFGE patterns to compare the correlations among genetic subtypes in several serotypes. The DNA fragments digested with Sma I and Apa I were resolved by PFGE. The PFGE patterns digested with Sma I were better than Apa I for analysis. In the DNA fragments digested with Sma 1, PFGE analysis of 56 S. pneumoniae isolates showed 25 different patterns. As a result, serotype was on the whole correlated to PFGE pattern on the ground that each different PFGE pattern by serotype was observed. This study can be utilized not only fur the study of incidence trend of domestic pneumococcal diseases but also as a useful basic data for the development of identification tool and treatment.

• 한국전문물리치료학회지
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• 제3권3호
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• pp.67-81
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• 1996

This study was performed to assess the efficacy of high voltage pulsed galvanic current for the healing of wounds in rabbits. Skin wounds were created laterally on the flank of 12 domestic rabbits($3{\times}3cm$). The wounds of each group were treated with an intensity of 170 V at a frequency of 70 pulses per second, which was applied for 30 minutes a day for 10 days. The experimental groups were randomly assigned to either EXP I (n=3), EXP II(n=3), EXP III(n=3) or control(n=3). Each group was stimulated under the following conditions : 1) EXP I (Negative polarity), 2) EXP II (Change in polarity, negative electrode stimulation during the first 3 days and then positive electrode stimulation from 4 to 10 days), 3) EXP III(Positive polarity), 4) control(No stimulation). An active electrode was placed over the wound and a dispersive electrode on the buttock. The rate of wound closure was compared with the original wound size, evaluated by a tracing film in each measurement period. Finally, on the wound in each group, skin tissue was excised for histological evaluation after treatment for 10 days. The results obtained are as follows : 1) It was found that the control group did not show a complete remodeling of epitherial layer and had a chronic inflammatory response. Judging from the irregularity of intercellular space and the loose alignment of connective tissue, these findings show that wound healing was delayed. 2) EXP I showed a significant bactericidal effect, but a moderate response of vasodilation. The rate of wound closure was slower when compared with EXP II, III. 3) EXP II showed a complete remodeling of epitherial layer and a positive repair of connective tissue. Its rate of wound closure was best when compared with the others. 4) EXP III had a slower rate of wound closure than EXP II, but judging from the greater proliferation of collagen fibers and the dense alignment of connective tissue, this positive electrode was very effective in the formation of neo - connective tissue.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.338.2-338.2
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• 2016

Al doped ZnO (AZO) thin films were deposited on Si substrates with rod-shaped-surface by pulsed laser deposition method (PLD). Si-rods were prepared through chemical etching. To analyze the influence on the formation of the rod structure, samples with various chemical etching conditions such as AgNO3/HF ratio, etching time, and solution temperature were prepared. The morphology of Si-rod structures were examined by FE-SEM. Fig. 1 shows a typical structure of n-AZO/p-Si-rod juncions. The fabricated n-AZO/p-Si-rod devices exhibited p-n diode current-voltage characteristics. We compared the I-V characteristics of n-AZO/p-Si-rod devices with the samples without Si-rod structure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.432-432
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• 2009

본 연구에서는 HW-PLD(Hot-walled Pulsed Laser Deposition) 법을 이용하여 ZnO 나노와이어를 $Al_2O_3$ 기판 위에 성장하였다. 성장된 ZnO 나노와이어는 SEM, XRD, PL 분석을 통하여 구조적 특성을 확인하였으며, 성장된 나노와이어를 photolithography 공정을 통하여 FET(Field Effect Transistor)소자를 제작하였다. 제작된 소자의 I-V 특성 측정 결과 Ti/Au 전극과 ZnO nanowire 채널 간에 ohmic 접합이 형성된 것을 확인하였으며 게이트 전압의 증가에 따라 소스와 드레인 사이의 전류가 증가하는 전형적인 n-type FET소자 특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.126-129
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• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

• Transactions on Electrical and Electronic Materials
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• 제3권1호
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• pp.1-3
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• 2002

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed typical I-V characteristics. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.126-129
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• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process ws performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.