• 한국진공학회지
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• 제6권2호
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• pp.114-121
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• 1997

투명전도성 산화주석 박막이 펄스레이저증착에 의하여 파이렉스유리 기판상에 제조 되었다. 진공, $O_2$, 및 $Sn(CH_3)_4$분위기에서 Nd-YAG레이저 빛살이 다결정 $SnO_2$ 타겟을 융제 하여 실온에서 기판상에 박막을 증착시키고, 증착된 막을 230, 420, 및 $610^{\circ}C$에서 각각 2시 간 동안 공기중에서 열처리하였다. 박막의 특성이 UV-VIS-NIR 분광법과 X-선 회절법에 의하여 조사되고, 전기적 성질이 촉심식법으로 구해진 막의 두께와 함께 사점탐침법에 의하 여 측정되었다. $Sn(CH_3)_4$이 존재할 때 $SnO_2$상들이 실온에서조차 성장되는 것이 관찰되었다. 이는 레이저 융제 동안 발생된 마이크로플라즈마가 전구물질분자의 분해에 중요한 역할을 함을 시사한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.571-571
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• 2012

We discovered the formation of C60 aggregates in solution by means of photoluminescence spectroscopic study on C60 in solutions. From the in-depth investigation of temperature dependence of the luminescence of C60 in toluene, benzene and CS2 solutions, we reported that the C60 aggregates are formed during cooling at the freezing temperature of these solvents. Furthermore, the C60 aggregates can be changed to stable structures by irradiating with UV pulse-laser (Nd:YAG laser, 355nm). As a consequence, we could obtain nano-scale photo-polymerized C60 clusters, which appear as round-shaped nano- scale particles in high resolution transmission electron-microscopy (HRTEM) images. However, the yield of the nano-scale C60 clusters obtained by this method is too small. So we designed and developed a system to obtain C60 cluster of macroscopic quantity by using ultrasonic nebulizer. In this system, C60 solution was vaporized to several micro-sized droplets in vacuum, resulting in the formation of C60 aggregates by evaporating solvent (toluene). The system was invented to produce nano-scale carbon clusters by the irradiation of UV light upon C60 aggregates in vacuum. We have characterized the products, C60 cluster, obtained from the system by using UV absorption spectra and HPLC spectra. Although the products have a possibility of inclusion various forms of C60 cluster, results support that the product formed from the system by using vaporizer method establishes a new method to obtain C60 cluster in macroscopic quantity. In the presentation, the details of the system and the results of characterization are reported.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.178-178
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• 2016

Every display is equipped with a cover glass to protect the underneath displaying devices from mechanical and environmental impact during its use. The strengthened glass such as Gorilla glass.$^{TM}$ has been exclusively adopted as a cover glass in many displays. Conventionally, the strengthened glass has been manufactured via ion-exchange process in wet salt bath at high temperature of around $500^{\circ}C$ for hours of treatment time. During ion-exchange process, Na ions with smaller diameter are substituted with larger-diameter K ions, resulting in high compressive stress in near-surface region and making the treated glass very resistant to scratch or impact during its use. In this study, PIIID (plasma immersion ion implantation and deposition) technique was used to implant metal ions into the glass surface for strengthening. In addition, due to the plasmonic effect of the implanted metal ions, the metal-ion implanted glass samples got colored. To implant metal ions, plasma immersion ion implantation technique combined with HiPIMS method was adopted. The HiPIMS pulse voltage of up to 1.4 kV was applied to the 3" magnetron sputtering targets (Cu, Ag, Au, Al). At the same time, the sample stage with glass samples was synchronously pulse-biased via -50 kV high voltage pulse modulator. The frequency and pulse width of 100 Hz and 15 usec, respectively, were used during metal ion implantation. In addition, nitrogen ions were implanted to study the strengthening effect of gas ion implantation. The mechanical and optical properties of implanted glass samples were investigated using micro-hardness tester and UV-Vis spectrometer. The implanted ion distribution and the chemical states along depth was studied with XPS (X-ray photo-electron spectroscopy). A cross-sectional TEM study was also conducted to investigate the nature of implanted metal ions. The ion-implanted glass samples showed increased hardness of ~1.5 times at short implantation times. However, with increasing the implantation time, the surface hardness was decreased due to the accumulation of implantation damage.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.176.2-176.2
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• 2013

Property of optical diagnostics for pulse-discharged plasma in liquid and its biological applications to proteins are investigated by making use of high voltage Marx generator. The Marx generator has been consisted of 5 stages, where each charging capacitor is 0.5 ${\mu}F$, to generate a high voltage pulse with rising time of $1{\mu}s$. We have applied an input voltage of 6 kV to the each capacitor of 0.5 ${\mu}F$. High voltage pulsed plasma has been generated inside a polycarbonate tube by a single-shot operation, where the breakdown voltage is measured to be 7 kV, current of 1.2 kA, and pulse width of ~ 1 ${\mu}s$ between the two electrodes of anode-cathode whose material is made of tungsten pin, which are immersed into the liquids. We have investigated the emitted hydrogen lines for optical diagnostics of high voltage pulsed plasma. The emission line of 656.3 nm from $H-{\alpha}$ and 486.1 nm from $H-{\beta}$ have been measured by a monochromator. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium conditions, the electron temperature and density of the high voltage pulsed plasma in liquid could be obtained by the Stark broadening of optical emission spectroscopy. For the investigation of the influence of pulsed plasma on biological proteins, we have exposed it onto the proteins such as hemoglobin and myoglobin. The structural changes in these proteins and their analysis have also been obtained by circular dichroism (CD) and ultraviolet (UV) visible spectroscopy.

• 전기학회논문지
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• 제58권3호
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• pp.559-565
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• 2009

In this paper, we invented a new and unique technique for the sterilization of Escherichia coli(E. coli) in polluted water. We applied a rich ultra-violet(UV) light from pulsed xenon flashlamp and photocatalyst(TiO2) to sterilize E. coli in polluted water. This method based on the use of UV light and photocatalyst is eco-friendly and does not cause secondary pollution. The proposed elliptical reactor is able to concentrate on quartz sleeve coated TiO2 or general quartz sleeve. The primary objective of our research was to determine the important parameters such as pulse repetition rate and input voltage and to know on the sterilizing efficiency of quartz sleeve coated TiO2 and general quartz sleeve. We obtained to achieve 99.999% sterilization in as little as 6 pulses at 800V in case of quartz sleeve coated Ti02, and 10 pulses at 800V in case of general quartz sleeve for 5 minutes. Although transmitted light of quartz sleeve coated TiO2 is deceased, the sterilizing efficiency is increased by 40% than general quartz sleeve. The reason of high sterilizing efficiency is that generated hydroxyl radical(OH) by photocatalyst and is able to concentrate light at a focus by using elliptical reactor.

• Natural Product Sciences
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• 제25권3호
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• pp.222-227
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• 2019

Quantitative nuclear magnetic resonance (qNMR) is a well-established method adopted by international pharmacopoeia for quantitative and purity analyses. Emodin is a type of anthraquinone, well known as the main active component of Fabaceae, Polygonaceae and Rhamnaceae. Purity analysis of emodin is usually performed by using the high-performance liquid chromatography (HPLC)-UV method. However, it cannot detect impurities such as salts, volatile matter, and trace elements. Using the qNMR method, it is possible to determine the compound content as well as the nature of the impurities. Several experimental parameters were optimized for the quantification, such as relaxation delay, spectral width, number of scans, temperature, pulse width, and acquisition time. The method was validated, and the results of the qNMR method were compared with those obtained by the HPLC and mass balance analysis methods. The qNMR method is specific, rapid, simple, and therefore, a valuable and reliable method for the purity analysis of emodin.

• Transactions on Electrical and Electronic Materials
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• 제13권5호
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• pp.245-247
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• 2012

In this study, ZnO films have been grown on PES (polyethersulfone) of flexible polymer substrate by PLD (pulsed laser deposition) and characterized for crystalline and optical properties. Growing conditions were changed with substrate temperatures ranging from 50 to $200^{\circ}C$ and laser power density ranging from 0.2 to $0.4J/cm^2$. When ZnO thin films are deposited at low temperature with a small laser power density, the (002) peaks of XRD to signify the crystal quality of ZnO thin films appear to be very weak and the (101) peaks to signify the chemical composition of oxygen and zinc are strong. The (002) peaks increase with the substrate temperature and laser power density because the energy needed for the supply of the combination regarding zinc and oxygen has increased. In this study, the best condition for growing ZnO thin film on PES is at a substrate temperature of $200^{\circ}C$ and with a laser density of $0.3J/cm^2$. The characteristics of PL were measured by UV and green luminescence.

• 한국전기전자재료학회논문지
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• 제23권3호
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• pp.199-205
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• 2010

The crystallization speed (v) of amorphous (InTe)$_x$(GeTe) (x = 0.1, 0.3 and 0.5) films and their thermal, optical and electrical behaviors have been investigated using nano-pulse scanner (wavelength = 658 nm, laser beam diameter < 2 ${\mu}m$), X-ray diffraction (XRD), 4-point probe and UV-vis-IR spectrophotometer. These results were compared with those of $Ge_2Sb_2Te_5$ (GST) film, comprehensively utilized for phase-change random access memory (PRAM). Both v-value and thermal stability of (InTe)$_{0.1}$(GeTe) and (InTe)$_{0.3}$(GeTe) films could be enhanced in comparison with those of the GST. Contrarily, the v-value in the (InTe)$_{0.5}$(GeTe) film was so drastically deteriorated that we could not quantitatively evaluate it. This deterioration is thought because amorphous (InTe)$_{0.5}$(GeTe) film has relatively high reflectance, resulting in too low absorption to cause the crystallization. Conclusively, it could be thought that a proper compositional (InTe)$_x$(GeTe) films (e.g., x < 0.3) may be good candidates with both high crystallization speed and thermal stability for PRAM application.

• 대한금속재료학회지
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• 제48권5호
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• pp.449-455
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• 2010

To enhance the efficiency of dye sensitized solar cells, we proposed crystalline anatase-$TiO_{2}$ by using a low temperature process ($150^{\circ}C{\sim}250^{\circ}C$). We successfully fabricated 30 nm-$TiO_{2}$ at a fixed atomic layer deposition condition of 1.0 sec of TDMAT pulse, 20 sec of TDMAT purge, 0.5 sec of H$_{2}$O pulse, and 20 sec of H$_{2}$O purge. In order to examine the microstructure, phase, and band-gap of the TiO$_{2}$ respectively, we employed a Nano-Spec, transmission electron microscope, high resolution XRD, Auger electron spectroscopy, scanning probe microscope, and UV-VIS-NIR. We were able to fabricate a crystalline anatase-phase of 30 nm-TiO$_{2}$ successfully at temperatures above $180^{\circ}C$. Our results showed that our proposed low temperature ALD process (below $200^{\circ}C$) might be applicable to glass and flexible polymer substrates.

• 생명과학회지
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• 제13권4호
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• pp.522-528
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• 2003

본 연구는 출아형 효모 Saccharomyces cerevisiae에서 자외선의 상해 시 이를 정상으로 회복시키는 절제회복 (excision repair) 유전자로 알려진 RADA4의 특성 규명을 위하여 균류 Coprinus cinereus에서 이와 유사한 유전자를 분리하였다. RAD4 유사 유전자를 분리하기 위하여 균류 C. cinereus의 염색체 DNA를 전기영동하여 분리한 다음 효모 RAD4 DNA를 probe로하여 이와 hybridization하였다. 이 결과 RAD4 유사 유전자는 3.2 kb의 insert DNA를 갖고 있었다. 또한 Southern hybridization으로 이 유사 유전자는 fungus C. cinereus의 염색체에 존재함을 확인하였다. 분리한 RAD4 유사 유전자의 전사체 크기는 2.5 kb 였으며, 자외선의 상해 시 전혀 'inducibility가 없음을 Northern hybridization으로 확인하였다. 또한 유사유전자 부분을 삭제하였을 때 이 부분이 없는 세포는 전혀 생존을 못하였다. 이 결과 분리한 RAD4 유사유전자는 세포의 생존에 관여함을 알 수 있었다.