• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.282-282
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• 2013

그래핀(Graphene)은 열 전도도가 높고 전자 이동도(200 000 cm2V-1s-1)가 우수한 전기적 특성을 가지고 있어 차세대 전자재료로써 유망한 후보로 간주되어 왔다. 최근에는 아크 방출(Arc discharge method), 화학적 기상 증착법(Chemical vapor deposition; CVD), 이온-조사법(Ion-irradiation) 등을 이용한 이종원자(Hetero atom)도핑과 화학적 처리를 이용한 기능화(Functionalization)등의 방법으로 그래핀의 전도도를 향상시킬 수 있었다. 그러나 이러한 방법들은 기판의 표면을 거칠게 하며, 그래핀에 많은 결함들이 발생한다는 단점이 있다. 이러한 단점을 극복하기 위해 자가 조립 단층막법(Self-Assembled Monolayers; SAMs)을 이용하여 기판을 기능화한 후 그 위에 그래핀을 전사하면, 자가 조립 단층막의 기능기에 따라 그래핀의 일함수를 조절 가능하고 운반자 농도나 도핑 유형을 변화시켜 소자의 전기적 특성을 최적화 할 수 있다 [1-3]. 본 연구에서는 PET(polyethylene terephthalate) 기판에 SAMs를 이용하여 유연하고 투명한 그래핀 전극을 제작하였다. 자외선 오존처리 (UV ozone treatment)를 이용하여 PET 기판 표면 위에 하이드록실 기(Hydroxyl group; -OH)를 기능화 화였고 이를 접촉각 측정(Contact angle measurement)을 통해 확인하였다. 또한 3-Aminopropyltriethoxysilane(APTES)와 톨루엔 (toluene)을 이용하여 PET 기판 표면 위의 하이드록실 기 위에 아민 기(Amine group; -NH2)를 기능화 하였고 이를 X-선 광전자 분광법(X-ray photoelectron spectroscopy: XPS)으로 분석하였다. 이렇게 만들어진 PET기판 표면 위에 화학적 기상 증착법을 이용하여 합성한 대면적의 균일한 그래핀을 전사하였다. NH2그룹에 의해 그래핀에 도핑 효과가 나타난 것을 라만 분광법(Raman spectroscopy)과 전류-전압 특성곡선(I-V characteristic curve)을 이용하여 확인하였다. 본 연구 결과는 유연하고 투명한 기판 위에 안정적이면서 패턴이 가능하기 때문에 그래핀을 기반으로 하는 반도체 소자에 적용 가능할 것이라 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.179.2-179.2
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• 2013

A large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER device. Negative hydrogen ion sources are major components of neutral beam injection (NBI) systems in future large-scale fusion experiments such as ITER and DEMO. The RF sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck-Institute for Plasma Physics), Garching, for the ASDEX-U and W7-AS neutral beam heating systems. Ion sources of the first NBI system (NBI-1) for the KSTAR tokamak have been developed successfully with a bucket plasma generator based on the filament arc discharge, which have contributed to achieve a good plasma performance such as 15 sec H-mode operation with an injection of 3.5 MW NB power. There is a development plan of RF ion source at the KAERI to extract the positive ions, which can be used for the second NBI system (NBI-2) of the KSTAR and to extract the negative ions for future fusion devices such as Fusion Neutron Source and Korea-DEMO. The development progresses of RF ion source at the KAERI are described in this presentation.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.557-575
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• 2020

Plasma blasting which is generated by high voltage arc discharge of electricity is applied to soil mass to improve permeability of soil and cleaning efficiency of oil contamination. A new high voltage generator was manufactured and three types of soil including silty sand, silty sand mixed with lime and silty sand mixed with cement were prepared. Small and large soil columns were produced using these types of soil and plasma blasting was performed within soil columns to investigate the variation of soil volume penetrated by fluid and permeability. Soil volume penetrated by fluid increased by 11~71% when plasma blasting was applied in soil. Although plasma blasting with low electricity voltage induced horizontal fracture and fluid penetrated along this weak plane, plasma blasting with high voltage induced spherical penetration of fluid. Plasma blasting increased the permeability of soil. Permeabilty of soils mixed with lime and cement increased by 450~1,052% with plasma blasting. Permeability of soil increased as discharge voltage increased when plasma blasing was applied once. However, several blastings with the same discharge voltage increase or decrease permeability of soil. Oil contaminated soil was prepared by adding diesel into soil artificially and plasma blasting was performed in these oil contaminated soil. Cleaning efficiency increased by average of 393% for soil located nearby the blasting and by average of 239% for soil located far from the blasting. Cleaning efficiency did not show any correlation with discharge voltage. All these results indicated that plasma blasting might be used for in-situ cleaning of oil contaminated soil because plasma blasting increased permeability of soil and cleaning efficiency.

• Electrical & Electronic Materials
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• v.12 no.7
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• pp.7-11
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• 1999

Fully sealed field emission display in size of 4.5 inch has been fabricated using single-wall carbon nanotubes-organic vehicle com-posite. The fabricated display were fully scalable at low temperature below 415$^{\circ}C$ and CNTs were vertically aligned using paste squeeze and surface rubbing techniques. The turn-on fields of 1V/${\mu}{\textrm}{m}$ and field emis-sion current of 1.5mA at 3V/${\mu}{\textrm}{m}$ (J=90${\mu}{\textrm}{m}$/$\textrm{cm}^2$)were observed. Brightness of 1800cd/$m^2$ at 3.7V/${\mu}{\textrm}{m}$ was observed on the entire area of 4.5-inch panel from the green phosphor-ITO glass. The fluctuation of the current was found to be about 7% over a 4.5-inch cath-ode area. This reliable result enables us to produce large area full-color flat panel dis-play in the near future. Carbon nanotubes (CNTs) have attracted much attention because of their unique elec-trical properties and their potential applica-tions [1, 2]. Large aspect ratio of CNTs together with high chemical stability. ther-mal conductivity, and high mechanical strength are advantageous for applications to the field emitter [3]. Several results have been reported on the field emissions from multi-walled nanotubes (MWNTs) and single-walled nanotubes (SWNTs) grown from arc discharge [4, 5]. De Heer et al. have reported the field emission from nan-otubes aligned by the suspension-filtering method. This approach is too difficult to be fully adopted in integration process. Recently, there have been efforts to make applications to field emission devices using nanotubes. Saito et al. demonstrated a car-bon nanotube-based lamp, which was oper-ated at high voltage (10KV) [8]. Aproto-type diode structure was tested by the size of 100mm $\times$ 10mm in vacuum chamber [9]. the difficulties arise from the arrangement of vertically aligned nanotubes after the growth. Recently vertically aligned carbon nanotubes have been synthesized using plasma-enhanced chemical vapor deposition(CVD) [6, 7]. Yet, control of a large area synthesis is still not easily accessible with such approaches. Here we report integra-tion processes of fully sealed 4.5-inch CNT-field emission displays (FEDs). Low turn-on voltage with high brightness, and stabili-ty clearly demonstrate the potential applica-bility of carbon nanotubes to full color dis-plays in near future. For flat panel display in a large area, car-bon nanotubes-based field emitters were fabricated by using nanotubes-organic vehi-cles. The purified SWNTs, which were syn-thesized by dc arc discharge, were dispersed in iso propyl alcohol, and then mixed with on organic binder. The paste of well-dis-persed carbon nanotubes was squeezed onto the metal-patterned sodalime glass throuhg the metal mesh of 20${\mu}{\textrm}{m}$ in size and subse-quently heat-treated in order to remove the organic binder. The insulating spacers in thickness of 200${\mu}{\textrm}{m}$ are inserted between the lower and upper glasses. The Y\ulcornerO\ulcornerS:Eu, ZnS:Cu, Al, and ZnS:Ag, Cl, phosphors are electrically deposited on the upper glass for red, green, and blue colors, respectively. The typical sizes of each phosphor are 2~3 micron. The assembled structure was sealed in an atmosphere of highly purified Ar gas by means of a glass frit. The display plate was evacuated down to the pressure level of 1$\times$10\ulcorner Torr. Three non-evaporable getters of Ti-Zr-V-Fe were activated during the final heat-exhausting procedure. Finally, the active area of 4.5-inch panel with fully sealed carbon nanotubes was pro-duced. Emission currents were character-ized by the DC-mode and pulse-modulating mode at the voltage up to 800 volts. The brightness of field emission was measured by the Luminance calorimeter (BM-7, Topcon).

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.48-55
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• 2014

These Xenon flashlamp power supply for Ultra Violet has converter with high voltage conversion ratio. General model is composed of transformer with high voltage conversion ratio and voltage doubler rectifier circuit. Purpose of power supply leads dielectric breakdown of Xenon flashlamp and passes current rapidly. When passing current, it has to limit current to avoid over-heat, damage of electrode and acceleration of gas oxidation which are cause of performance degradation of lamps. Generally, inductors and resistors, which are called as "Ballast," are used to limit currents. Generally, Transformer has high turn ratio to make high voltages. But we can get high voltages using the transformer with low turn ratio which is driven with self resonance. Also, an advantage of self resonance is to make a circuit simply through impedance of transformer in resonance frequency which filters output voltage. As using an unique impedance of transformer, the circuit does not need other impedance elements like the ballast. So the power supply assures high efficiency of the arc discharge.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.400-401
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• 2012

그래핀(Graphene)은 열 전도도가 높고 전자 이동도(200 000 cm2V-1s-1)가 우수한 전기적 특성을 가지고 있어 전계 효과 트랜지스터(Field effect transistor; FET), 유기 전자 소자(Organic electronic device)와 광전자 소자(Optoelectronic device) 같은 반도체 소자에 응용 가능하다. 그러나 에너지 밴드 갭이 없기 때문에 소자의 전기적 특성이 제한되는 단점이 있다. 최근에는 아크 방출(Arc discharge method), 화학적 기상 증착법(Chemical vapor deposition; CVD), 이온-조사법(Ion-irradiation) 등을 이용한 이종원자(Hetero atom)도핑과 화학적 처리를 이용한 기능화(Functionalization) 등의 방법으로 그래핀을 도핑 후 에너지 밴드 갭을 형성시키는 연구 결과들이 보고된 바 있다. 그러나 이러한 방법들은 표면이 균일하지 않고, 그래핀에 많은 결함들이 발생한다는 단점이 있다. 이러한 단점을 극복하기 위해 자가조립 단층막(Self-assembled monolayers; SAMs)을 이용하여 이산화규소(Silicon oxide; SiO2) 기판을 기능화한 후 그 위에 그래핀을 전사하면 그래핀의 일함수를 쉽게 조절하여 소자의 전기적 특성을 최적화할 수 있다. SAMs는 그래핀과 SiO2 사이에 부착된 매우 얇고 안정적인 층으로 사용된 물질의 특성에 따라 운반자 농도나 도핑 유형, 디락 점(Dirac point)으로부터의 페르미 에너지 준위(Fermi energy level)를 조절할 수 있다[1-3]. 본 연구에서는 SAMs한 기판을 이용하여 그래핀의 도핑 효과를 확인하였다. CVD를 이용하여 균일한 그래핀을 합성하였고, 기판을 3-Aminopropyltriethoxysilane (APTES)와 Borane-Ammonia(Borazane)을 이용하여 각각 아민 기(Amine group; -NH2)와 보론 나이트라이드(Boron Nitride; BN)로 기능화한 후, 그 위에 합성한 그래핀을 전사하였다. 기판 위에 NH2와 BN이 SAMs 형태로 존재하는 것을 접촉각 측정(Contact angle measurement)을 통해 확인하였고, 그 결과 NH2와 BN에 의해 그래핀에 도핑 효과가 나타난 것을 라만 분광법(Raman spectroscopy)과 X-선 광전자 분광법(X-ray photoelectron spectroscopy: XPS)을 이용하여 확인하였다. 본 연구 결과는 안정적이면서 패턴이 가능하기 때문에 그래핀을 기반으로 하는 반도체 소자에 적용 가능할 것이라 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.434-434
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• 2012

Despite recent efforts for fabricating flexible transparent conducting films (TCFs) with low resistance and high transmittance, several obstacles to meet the requirement of flexible displays still remain. Indium tin oxide (ITO) thin films, which have been traditionally used as the TCFs, have a serious obstacle in TCFs applications. SWNTs are the most appropriate materials for conductive films for displays due to their excellent high mechanical strength and electrical conductivity. Recently, it has been demonstrated that acid treatment is an efficient method for surfactant removal. However, the treatment has been reported to destroy most SWNT. In this work, the fabrication by the spraying process of transparent SWNT films and reduction of its sheet resistance by Au-ionic doping treatment on PET substrates is researched. Arc-discharge SWNTs were dispersed in deionized water by adding sodium dodecyl sulfate (SDS) as surfactant and sonicated, followed by the centrifugation. The dispersed SWNT was spray-coated on PET substrate and dried on a hotplate. When the spray process was terminated, the TCF was immersed into deionized water to remove the surfactant and then it was dried on hotplate. The TCF film was then was doped with Au-ionic doping treatment, rinsed with deionized water and dried. The surface morphology of TCF was characterized by field emission scanning electron microscopy. The sheet resistance and optical transmission properties of the TCF were measured with a four-point probe method and a UV-visible spectrometry, respectively. This was confirmed and discussed on the XPS and UPS studies. We show that 87 ${\Omega}/{\Box}$ sheet resistances with 81% transmittance at the wavelength of 550 nm. The changes in electrical and optical conductivity of SWNT film before and after Au-ionic doping treatments were discussed. The effects of hole transport interface layer using Au-ionic doping SWNT on the performance of organic solar cells were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.412-412
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• 2009

Carbon-based nano materials have a significant effect on various fields such as physics, chemistry and material science. Therefore carbon nano materials have been investigated by many scientists and engineers. Especially, since graphene, 2-dimemsonal carbon nanostructure, was experimentally discovered graphene has been tremendously attracted by both theoretical and experimental groups due to their extraordinary electrical, chemical and mechanical properties. Electrical conductivity of graphene is about ten times to that of silicon-based material and independent of temperature. At the same time silicon-based semiconductors encountered to limitation in size reduction, graphene is a strong candidate substituting for silicon-based semiconductor. But there are many limitations on fabricating large-scale graphene sheets (GS) without any defect and controlling chirality of edges. Many scientists applied micromechanical cleavage method from graphite and a SiC decomposition method to the fabrication of GS. However these methods are on the basic stage and have many drawbacks. Thereupon, our group fabricated GS through Thermo-electrical Pulse Induced Evaporation (TPIE) motivated by arc-discharge and field ion microscopy. This method is based on interaction of electrical pulse evaporation and thermal evaporation and is useful to produce not only graphene but also various carbon-based nanostructures with feeble pulse and at low temperature. On fabricating GS procedure, we could recognize distinguishable conditions (electrical pulse, temperature, etc.) to form a variety of carbon nanostructures. In this presentation, we will show the structural properties of OS by synthesized TPIE. Transmission Electron Microscopy (TEM) and Optical Microscopy (OM) observations were performed to view structural characteristics such as crystallinity. Moreover, we confirmed number of layers of GS by Atomic Force Microscopy (AFM) and Raman spectroscopy. Also, we used a probe station, in order to measure the electrical properties such as sheet resistance, resistivity, mobility of OS. We believe our method (TPIE) is a powerful bottom-up approach to synthesize and modify carbon-based nanostructures.

• Asian Oncology Nursing
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• v.5 no.1
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• pp.52-62
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• 2005

Purpose: This study was to analyze the research trend centering on the theses to cancer nursing research in digestive system released in Korea. Method: The researcher collected the academic degrees and theses published on the book of the academic soceity from January 1993 to August, 2004, and examined 38 domestic papers of cancer nursing research in digestive system. Results: 1) As for the subject, the results were : patients with stomach cancer 25(66%), colon cancer 4(11%), rectal cancer 3(8%), and others(taxi drivers 2, family of cancer patents. 2) As for the research designs the result were : quantitative studies were 33(87%), and qualitative studies were 9(23%). 3) As for key concepts of survey, the results were : life patterns of patients with rectal cancer, oral intake of stomach cancer patients, fatigue of stomach cancer patients undergoing chemotherapy, nursing needs when discharging from hospital after operation with gastrectomy, and so on. 4) As for the comparative studies, the results were : risk factors between colorectal patients and general population, early symptom and risk factors between stomach cancer patients and general population, and risk factors between stomach cancer and patients with gastritis. 5) As for main concepts of correlational studies, the results were : quality of life, health belief, fatigue, health promotion behavior, social support, straitanxiety. 6) The treatment of experimental research, the results were : information services, arc reflex massage, acupressure, educational program for discharge, 7)As for the qualitative studies, in terms of subjects, stomach cancer patients were 2, spouse of patients with stomach cancer was 1, rectal cancer patients were 2. In the theme of the qualitative studies, the results were: experience of family of patients with stomach cancer, experience of long term survival of patients with rectal cancer, experience of disease process of rectal cancer patiens. 8) As for the used instrument in studies, the results were : Strait-anxiety Scale by Spielberger, Nausea and Vomiting Scale by Rhodes, Social support by Tae and Lee, Health belief by Champion, Becker, and Moon. QOL by NCCN, Roh, Pdilla, Kwon, Revised Fatigue Scale by Piper, Health Locus of Control by Wallston and Wallston, Uncertainty Scale by Mishel. Conclusions: More research needs to be encouraged in various subject of cancer patients in digestive system. More nonexperimental and experimental researches should be conducted for the establishment of the basis of practical and theoretical framework and the providing good quality of care for cancer patients.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.48-53
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• 2006

The purpose of this paper is to investigate the optimal condition of the SynGas production by reforming of propane using plasmatron. Plasma was generated by air and arc discharge. The effects of applied steam, $CO_2$ or Ni-catalyst on propane conversion, yield of hydrogen and $H_2/CO$ ratio as well as correlation of syngas were studied. When the variations of $O_2/C_3H_8$ flow ratio, $H_2O/C_3H_8$ flow ratio and $CO_2/C_3H_8$ flow ratio were $0.94{\sim}1.48,\;4.3{\sim}10\;and\;0.8{\sim}3.05$ respectively, Under the condition mentioned above, result of $H_2O/C_3H_8$ flow ratio was maximum $H_2$ concentration, or $28.2{\sim}31.6%$, and result of $H_2O/C_3H_8$ flow ratio with catalyst was minimum CO concentration or $6.6{\sim}7.1%$ and the ratio of hydrogen to carbon monoxide($H_2/CO$) were $3.89{\sim}4.86$.