• 지질공학
• /
• 제30권4호
• /
• pp.557-575
• /
• 2020

유류오염 토양의 투수성 및 정화효율을 개선하기 위하여 고전압 아크 방전에 의한 플라즈마 블라스팅을 토양에 적용하였다. 이 연구를 위하여 고전압 발생장치를 새로 제작하였고, 실트질 모래인 토양시료, 토양시료에 소석회를 혼합한 시료와 토양시료에 시멘트를 혼합한 세 종류의 토양시료를 다져서 소형 토조와 대형 토조를 제작한 후 각각의 토조내에서 플라즈마 블라스팅을 시행하여 유체확산의 범위와 투수성의 변화를 측정하였다. 플라즈마 블라스팅이 시행된 토양시료에서는 플라즈마 블라스팅이 시행되지 않은 대조군에 비해 유체의 확산 부피가 약 11~71% 증가하였다. 낮은 전압하에서 플라즈마 블라스팅이 시행되면 토양 내에서는 구조적 취약면(다짐면)을 따라 수평적 확산이 우세하게 나타났으나 높은 전압에 의한 플라즈마 블라스팅은 토양 내에 구형의 입체적인 확산을 발생시켰다. 플라즈마 블라스팅은 투수성 또한 증가시켰으며, 소석회 및 시멘트가 혼합된 토양에서 더욱 뚜렷하게 관찰되어, 플라즈마 블라스팅이 시행된 시료들은 대조군 시료에 비해 투수계수가 450~1,052% 범위로 증가하였다. 플라즈마 블라스팅이 1회만 실시된 토양시료의 투수계수는 방전 전압이 높아질수록 증가하였으나 동일한 전압으로 여러 번의 블라스팅이 시행된 토양시료의 투수계수는 증가하거나 감소하였다. 토양시료에 경유를 이용하여 인위적으로 오염시킨 토양시료에 플라즈마 블라스팅을 실시하여 정화효율을 측정하였다. 플라즈마 블라스팅이 시행되면, 방전지점 근처의 토양에서는 평균 393%, 방전지점으로부터 20 cm 이상 이격된 하부 토양에서는 평균 239% 정도의 정화효율이 개선되었으나 방전 전압과 정화효율은 상관성을 보이지 않았다. 위의 결과는 플라즈마 블라스팅이 토양의 투수성과 정화효율을 상당히 개선하므로, 유류오염 토양의 원위치 정화에 효율적으로 이용될 가능성을 보여주었다.

• E2M - 전기 전자와 첨단 소재
• /
• 제12권7호
• /
• pp.7-11
• /
• 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
• /
• 제38권1호
• /
• pp.48-55
• /
• 2014

UV 발생용 플래시램프의 전원공급장치는 강력한 아크방전을 유발하기 위하여 높은 승압 비를 갖는 전압변환회로를 가지고 있다. 일반적인 구조는 높은 승압비의 트랜스포머와 배전압정류방식(코크라프트 올튼 회로 등)으로 방전관의 절연을 파괴함과 동시에 방전관에 전류를 급격히 통과시키는 방식으로 구동한다. 이 때, 제논방전관의 방전특성상 입력전류를 제한하지 않으면 방전관의 과다 발열, 전극손실, 봉입기체의 산화가속 등으로 수명저하의 원인이 되므로, 반드시 방전관에 유입되는 전류를 제한해야 되며, 이를 Ballast라 하는데 일반적으로 인덕터나 저항을 사용하여 인입전류량을 제한한다. 트랜스포머의 자가 공진(self-resonance)을 이용하면 낮은 1, 2차권선 비에도 고유주파수의 전후에서 비교적 높은 피크 전압을 얻을 수 있다. 또한 트랜스포머의 특정주파수에서 고유임피던스 성분을 이용하여 출력전압을 필터링하면 제논방전관이 자가 발진방식으로 동작하므로 종래의 회로구성보다 간단하고 경제적인 아크방전 파워 스테이지의 구성이 가능하다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.400-401
• /
• 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.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.434-434
• /
• 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.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.412-412
• /
• 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.

• 종양간호연구
• /
• 제5권1호
• /
• pp.52-62
• /
• 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.

• 대한환경공학회지
• /
• 제28권1호
• /
• pp.48-53
• /
• 2006

본 논문에서는 plasmatron을 사용하여 프로판의 개질에 의해 SynGas 생산의 최적의 조건을 연구하였다. 플라즈마는 공기와 아크 방전에 의해 생성되며 합성 가스의 상관 관계뿐만 아니라 수증기, $CO_2$ 또는 반응기에 촉매를 추가하여 프로판 전환에 미치는 영향과 수소의 수율, $H_2/CO$ 비에 대해 연구하였다. $O_2/C_3H_8$ 유량비, $H_2O/C_3H_8$ 유량비와 $CO_2/C_3H_8$ 유량비를 각각 $0.94{\sim}1.48,\;4.3{\sim}10$과 $0.8{\sim}3.05$로 변화하였을 때, $H_2O/C_3H_8$ 유량비의 변화 결과가 최대 $28.2{\sim}31.6%$의 $H_2$ 농도를 나타냈으며, 촉매를 추가하고 $H_2O/C_3H_8$ 유량비의 변화결과 $6.6{\sim}7.1%$의 최소 CO 농도를 나타냈다. 그리고 $H_2/CO$ 비는 $3.89{\sim}4.86$을 나타냈다.

• 대한약리학회지
• /
• 제23권2호
• /
• pp.57-75
• /
• 1987

Two modalities of gonadotropin secretion, pulsatile gonadotropin and preovulatory gonadotropin surge, have been identified in the mammals. Pulsatile gonadotropin secretion is modulated by the pulsatile pattern of GnRH release and complex ovarian steroid feedback actions. The neural mechansim that regulates the pulsatile release of GnRH in the hypothalamus is called "GnRH pulse generator". Ovarian steroids, estradiol and progesterone, appear to exert thier feedback effects both directly on the pituitary to modulate gonadotropin release and on a hypothalamic site to modulate GnRH release; estradiol primarily affects the amplitude while progesterone decreases the frequency of the pulsatile GnRH. Steroid hormones are known to affect catecholamine transmission in brain. MBH-POA is richly innervated by NE systems and close apposition of NE terminals and GnRH cell bodies occurs in the MBH as well as in the POA. NE normally facilitates pulsatile LH release by acting through ${\alpha}-receptor$ mechanism. However, precise nature of facilitative role of NE transmission in maintaining pulsatile LH has not been clearly understood. Close apposition of DA and GnRH terminals in ME might permit DA to influence GnRH release. Action of DA transmission probably is mediated by axo-axonic contacts between GnRH and DA fibers in the ME. Dopamine transmission does not normally regulate pulsatile LH release, but under certain conditions, increased DA transmission inhibit LH pulse. Endogenous opioid acts to suppress the secretion of GnRH into hypophysial portal circulation, thereby inhibiting gonadotropin secretion. However, an interaction between endogenenous opioid peptides and gonadotropin release is a complex one which involves ovarian hormones as well. LH secretion appears to be most suppressed by endogenenous opioids during the luteal phase, at a time of elevated progesterone secretion. The arcuate nucleus contains not only cell bodies for GnRH and ${\beta}-endorphin$ but also a dense aborization of fibers suggesting that GnRH release is changed by the interactions between GnRH and ${\beta}-endorphin$ cell bodies within the arcuate nucleus. The frequency and amplitude of pulsatile LH release seem to be increased during the preovulatory gonadotropin surge. Estradiol exerts positive feedback action on the hypothalamo-pituitary axis to trigger preovulatory LH surge. GnRH is also crucial hormonal stimulus for preovulatory LH surge. It is unlikely, however, that increased secretion of GnRH during the preovulatory gonadotropin surge represents an obligatory neural signal for generation of the LH discharge in primates including human. Modulation of preovulatory LH surge by catecholamines has been studied almost exclusively in rats. NE and E may be involved in distinct way to accumulate GnRH in the MBH and its release into the hypophysial portal system during the critical period for LH surge on proestrus in rats. However, the mechanisms whereby augmented adrenergic transmission may facilitate the formation and accumulation of GnRH in the ME-ARC nerve terminals before the LH surge have not been clearly understood.

• 한국자기학회지
• /
• 제22권3호
• /
• pp.79-84
• /
• 2012

나노크기의 물질이 가지는 새로운 특성을 응용하는 연구가 매우 활발하게 진행되어 지고 있다. 본 연구에서는 PAD법으로 제조한 ${\alpha}$-Fe 나노분말을 이용하여 높은 포화자화와 기계적인 경도, 화학적 안정성, 작은 입자로 인한 tape noise의 감소 등의 특성을 지니고 있는 질화철인 $Fe_4N$을 합성하고, 이를 환원/확산법과 $N_2$가스 질화법으로 합성한 $Fe_{17}Sm_2N_x$ 자성분말과 자성 특성을 비교하였다. $NH_3+H_2$(부피비 3 : 1) 혼합가스를 이용하였을 경우 $Fe_4N$의 생성 온도와 반응시간 등의 조건 변수를 통해 $400^{\circ}C$에서 4시간 동안 열처리함으로서 단일상의 $Fe_4N$이 생성되는 것을 관찰 할 수 있었으며, 나노크기의 $Fe_4N$ 분말과 마이크론 크기의 $Fe_{17}Sm_2N_x$ 분말의 포화자화의 값은 각각 149, 117 emu/g의 값을 나타내었다.