• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.197-197
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• 2012

Device 제작에 사용된 graphene은 일반적인 lithography 공정에서 resist residue에 의한 오염을 피할 수 없으며 이로 인하여 graphene의 pristine한 성질을 잃어버린다. 본 연구에서는 graphene을 저밀도의 argon inductively coupled plasma (Ar-ICP)를 통해 처리함으로서 graphene based back-gated field effect transistor (G-FET)의 특성변화를 유도한 결과에 대해서 보고한다. Argon capacitively coupled plasma (Ar-CCP)은 에 노출된 graphene은 강한 ion bombardment energy로 인하여 쉽게 planar C-C ${\pi}$ bonding (bonding energy: 2.7 eV)이 breaking되어 graphene의 defect이 발생되었다. 하지만 우리의 경우 저밀도의 Ar-ICP가 적용될 때 graphene의 defect이 제한되며 이와 동시에 contamination 만을 제거할 수 있었다. 소자의 전기적 측정 (Gsd-Vbg)을 통하여 contamination으로 인하여 p-doping된 graphene은 pristine 상태로 회복되었으며 mobility도 회복됨이 확인되었다. Ar-ICP를 이용한 graphene cleaning 방법은 저온공정, 대면적 공정, 고속공정을 모두 만족시키며 thermal annealing, electrical current annealing을 대체하여 graphene 기반 소자를 생산함에 있어 쉽고 빠르게 적용할 수 있는 강점이 있다.

• 대한치과기공학회지
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• 제27권1호
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• pp.65-71
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• 2005

Experimental Ti-13%Zr and Ti-13%Zr-5%Cu alloys were made in an argon-arc melting furnace. The grade 2 CP Ti was used to control. The alloys were cast into phosphate bonded $SiO_2$ investment molds using an argon-arc casting machine, and The hardness and microstructures of the castings were investigated in order to reveal their possible use for new dental casting materials and to collect useful data for alloy design. The hardness of the Ti-13%Zr-5%Cu alloy(379Hv) became higher than that of Ti-13%Zr(317Hv) alloy, and the hardness of this alloys became higher than that of CP Ti(247Hv). Increasing in the hardness of the Ti-13%Zr-5%Cu alloy was considered to be solid solution hardening as the Ti-Zr system shows a completely solid solution for both high temperature $\beta$phase and low temperature $\alpha$ phase and also the inclusion of the eutectoid structure($\alpha Ti+Ti_{2}Cu$). No martensitic structures are observed in the specimen made of CP Ti, but Ti-13%Zr and Ti-13%Zr-5%Cu alloys show a kind of martensitic structure. Ti-13%Zr-5%Cu shows the finest microstructure. From these results, it was concluded that new alloys for dental casting materials should be designed as Ti-Zr-Cu based alloys.

• 대한소아치과학회지
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• 제25권1호
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• pp.62-75
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• 1998

The main purpose of this study was to compare the anticariogenecity of glass ionomer restorative material polymerized by argon laser versus visible light, The results from the present study can be summarized as follows; 1. Under the polarized light microscope, the specimens of laser-cured group showed the shallower lesion body than that of visible-light cured group, both in the stage of lesion initiation and progression. 2. Glass ionomer material cured by visible light showed shallower body of lesion than that of composite resin cured by argon laser at the stage of lesion progression(p<0.05). It was suggested fluoride released from the glass ionomer might have the additive anticariogenic effect. 3. Statistical difference between groups on depth of lesion body was evident after lesion progression (p<0.05). It was suggested that anticariogenic effect by argon laser was more effective at the stage of lesion progression than the lesion initiation. 4. The increment of lesion body during progression was highest in group IV (p<0.05). 5. Based upon the above-mentioned results of this study, it can be concluded that the advantage of anticariogenic effect and short curing time of argon laser in glass ionomer polymerization should be considered in children and adolescents whose caries activity is relatively higher.

• Journal of Korean Vacuum Science & Technology
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• 제7권1호
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• pp.18-22
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• 2003

The optogalvanic effect is proposed and demonstrated as a technique for Penning ionization in a discharge of mixtures of metal vapors and rare gases. The gadolinium and argon mixture is used as a prototype. The lowest metastable of argon, 3P$_2$ (ls$\_$5/ in Paschen notation) at 93144 cm$\^$-1/, is within kT from the excited states of Gd ion. Thus Penning ionization occurs to an excited states of the ion. This process strongly alters the optogalvanic signal and has its own signatures.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제20권2호
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• pp.134-137
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• 2017

Gastric hemangioma in the neonatal period is a very rare cause of upper gastrointestinal bleeding. We present a case of hemangioma limited to the gastric cavity in a 10-day-old infant. A huge, erythematous mass with bleeding was observed on the lesser curvature side of the upper part of the stomach. Surgical resection was ruled out because the location of the lesion was too close to the gastroesophageal junction. Medical treatment with intravenous $H_2$ blockers, octreotide, packed red blood cell infusions, local epinephrine injection at the lesion site, application of hemoclip, and gel-form embolization of the left gastric artery did not significantly alter the transfusion requirement. Hemostasis was achieved with endoscopic argon plasma coagulation (APC). After two sessions of APC, complete removal of the lesion was achieved. APC was a simple, safe and effective tool for hemostasis and the ablation of gastric hemangioma without significant complications.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.261-268
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• 1999

Laser-induced thermochemical etching has been recognized as a new powerful method for processing a variety of materials, including metals, semiconductors, ceramics, insulators and polymers. This study presents characteristics of direct etching for Si substrate using focused argon ion laser beam in aqueous KOH and $CCl_2F_2$ gas. In order to determine process conditions, we first theoretically investigated the temperature characteristics induced by a CW laser beam with a gaussian intensity distribution on a silicon surface. Major process parameters are laser beam power, beam scan speed and reaction material. We have achieved a very high etch rate up to $434.7\mum/sec$ and a high aspect ratio of about 6. Potential applications of this laser beam etching include prototyping of micro-structures of MEMS(micro electro mechanical systems), repair of devices, and isolation of opto-electric devices.

• 한국재료학회지
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• 제16권2호
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• pp.116-122
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• 2006

The effects of milling time in argon and hydrogen atmospheres on the hydrogen sorption speed of a getter alloy, $Zr_{57}V_{36}Fe_{7}$, was studied. The hydrogen sorption speed of milled alloys was evaluated at room temperature. In argon, as the oxygen content increased with milling time, the hydrogen sorption speed decreased accordingly. In hydrogen, on the other hand, the oxygen content decreased at first with milling time but started increasing after 5 hrs of milling time. Similar to the case of argon, however, the hydrogen sorption speed changed exactly in the opposite direction with the oxygen content, exhibiting the maximum rate at 5 hrs. These results suggest that in both atmospheres the hydrogen sorption speeds are inversely related with the oxygen contents.

• 한국분말재료학회지
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• 제12권2호
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• pp.112-116
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• 2005

In the present study, the focus is on the analysis of carbothermal reduction of oxide powder prepared from waste WC/Co hardmetal by solid carbon under a stream of argon for the recycling of the WC/Co hard-metal. The oxide powder was prepared by the combination of the oxidation and crushing processes using the waste $WC-8 wt.\%Co$ hardmetal as the raw material. This oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and gases discharge of the mixture during carbothermal reduction was analysed using XRD and gas analyzer. The oxide powder prepared from waste $WC-8wt.\%Co$ hardmetal has a mixture of $WO_{3} and CoWO_{4}$. This oxide powder reduced at about $850^{\circ}C$, formed tungsten carbides at about $950^{\circ}C$, and then fully transformed to a mixed state of tungsten carbide (WC) and cobalt at about $1100^{\circ}C$ by solid carbon under a stream of argon. The WC/Co composite powder synthesized at $1000^{\circ}C$ for 6 hours from oxide powder of waste $WC-8wt.\%Co$ hardmetal has an average particle size of $0.3 {\mu}m$.

• 대한전자공학회논문지SD
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• 제39권4호
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• pp.35-40
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• 2002

일함수가 낮은 바나듐과 몰리브덴을 장벽금속으로 사용하여 초절전형 SBR을 제조하였다. 일함수가 낮은 장벽금속을 사용함으로서 나타나는 역방향 누설전류를 감소시키기 위해 n-Si층에 아르곤 이온을 1×10/sup 14/ ion/㎠, 40 keV로 주입하였다. 제조된 소자의 전기적 특성은 60 A/㎠의 동일한 전류밀도에서 Mo-SBR의 V/sub F/는 0.39 V이고 V-SBR은 0.25 V로서 매우 낮은 V/sub F/를 나타내었다. 이에 따라 아르곤 이온주입에 의해 제조된 Y-SBR의 역방향 누설전류는 일반적인 V-SBR과 비교하여 20㎂ 이상 감소됨을 확인할 수 있었다. 또한, 아르곤 이온주입으로 인한 소자의 특성저하는 나타나지 않았다.

• 한국환경과학회지
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• 제11권7호
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• pp.749-755
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• 2002

The effects of noble gas (such as helium, neon, argon, krypton, and xenon) on the sonolytic decomposition of water and 2-methyl-2-propanol(t-butanol) with 200 KHz high power ultrasound were investigated. The physical properties of the noble gas have an effect on the formation rate of products $(H_2O_2,\;H_2,\;O_2)$ and the decomposition rate on the sonolytic decomposition of water. The pyrolysis products, such as methane, ethane, ethylene, and acetylene are formed during the sonolytic decomposition of t-butanol. From the estimation of the ratio $[C_2H_4+C_2H_2] / [C_2H_6]$, the cavitation temperature would be varied by the used noble gas. In all cases for the sonolytic decomposition of water, t-butanol, and diethyl phthalate, the decomposition rates were xenon > krypton > argon > neon > helium with a significant difference and were closely correlated with the formation rate of OH radical and high temperature inside the cavitation bubble under each noble gas.