• 천문학회지
• /
• 제46권5호
• /
• pp.183-190
• /
• 2013

Recurring jets, which are jets ejected from the same site, are a peculiar type among various solar jet phenomena. We report such recurring jets ejecting from the same site above an active region on January 22, 2012 with high-resolution multi-wavelength observations from Solar Dynamics Observatory(SDO). We found that the recurring jets had velocities, lengths and lifetimes, but had similar directions. The visible brightening appeared at the jet base before each jet erupted. All the plasma produced by the recurring jets could not overcome the large coronal loops. It seemed that the plasma ejecting from the jet base was confined and guided by preexisting coronal loops, but their directions were not along the paths of the loops. Two of the jets formed crossing structures with the same preexisting filament. We also examined the photospheric magnetic field at the jet base, and observed a visible flux emergence, convergence and cancellation. The four recurring jets all were associated with the impulsive cancellation between two opposite polarities occurring at the jet base during each eruption. In addition, we suggest that the fluxes, flowing out of the active region, might supply the energy for the recurring jets by examining the SDO/Helioseismic and Magnetic Imager (HMI) successive images. The observational results support the magnetic reconnection model of jets.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.251-252
• /
• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.

• 대한소아치과학회지
• /
• 제29권1호
• /
• pp.19-29
• /
• 2002

본 연구의 목적은 다양한 중합과정에 따른 복합레진과 컴포머의 수축 양상을 스트레인 게이지법(strain gauge method)을 이용하여 평가해보고자 하는 것이었다. 광중합기는 기존의 할로겐 시스템인 XL 3000(3M, USA)과 최근 소개된 plasma arc curing 시스템인 Flipo(LOKKI, France)를 사용하였고, 충전 재료는 복합레진인 Z-100(3M, USA)과 컴포머인 Dyract AP(Dentsply, Germany)를 사용하였다. 주형과 치아 와동 내에 충전된 실험재료의 중합수축을 각각 측정하였으며, 만능시험기를 이용하여 압축강도를 측정하였다. 중합수축 측정 결과 모두 중합초기에는 일시적인 재료의 팽창을 나타냈고, 그 후 약 1분간은 수축량이 급격히 증가하다가 증가의 폭이 점차 감소하는 양상을 보였다. 전반적으로 컴포머를 사용한 군에 비해 복합레진을 사용한 군에서 중합수축이 크게 나타났으며 plasma arc curing 시스템을 사용한 군에 비해 기존의 광조사 시스템 군에서 더 큰 중합수축을 보였다. 압축 강도의 측정결과는 컴포머 군에 비해 복합레진 군에서 크게 나타났다. 이상의 결과를 종합해 볼 때, plasma arc curing unit와 컴포머의 사용은 시술시간의 단축과 항우식 효과를 감안한다면 소아치과 영역에서의 사용이 긍정적으로 고려될 수 있다고 생각된다.

• 치위생과학회지
• /
• 제9권5호
• /
• pp.525-530
• /
• 2009

이 연구는 35% 과산화요소를 이용한 전문가 치아미백술에 플라즈마 아크를 함께 적용하여 플라즈마 아크가 법랑질의 색조변화에 미치는 효과와 비커스경도와 주사전자현미경을 이용하여 법랑질 표면에 미치는 영향을 알아보고자 in vitro 평가를 시행하여 다음과 같은 결론을 얻었다. 1. 미백 횟수의 증가에 따라 색조변화량(${\Delta}E^*$)이 통계적으로 유의한 증가를 나타내었으며, 미백 제만 단독으로 적용한 대조군 보다 플라즈마 아프를 함께 적용하여 미백처리를 한 실험군의 색조변화량(${\Delta}E^*$)이 더 높게 나타나는 것을 알 수 있었다. 2. 미백처리 전 후 법랑질의 미세경도 측정 값을 분석한 결과 미백 처치를 함으로써 미세경도 값이 통계적으로 유의하게 감소되었고, 미백제에 플라즈마 아크를 함께 적용한 실험군에서 더 큰 미세경도의 감소가 나타나는 것을 알 수 있었다. 3. 주사전자현미경 관찰에서 미백 처치를 한 시료에서 법랑질 표면이 상당히 거칠어진 양상을 나타내는 것을 볼 수 있었다. 이상의 결과를 종합해 볼 때 전문가 치아미백술에서 플라즈마 아크를 함께 적용함으로써 색조변화를 더욱 상승시킬 수 있으나, 법랑질 표면의 미세경도와 형태변화를 증가시킬 수 있으므로 미백 효과는 증가시키면서 법랑질의 형태와 구조는 변화시키지 않는 안전한 미백 방법에 관한 연구가 이루어 져야 할 것으로 사료된다.

• 한국진공학회지
• /
• 제18권3호
• /
• pp.164-175
• /
• 2009

전산 유체 역학 코드를 사용하여 안테나 내장형 유도 결합 플라즈마 시스템의 가스 유동 특성, 전력 흡수, 전자 온도, 전자 밀도, 화학종의 분포에 대해서 살펴보았다. 복잡한 현실적 3차원 시스템에 대한 안정한 수치해의 도출을 위해서 최적화된 격자생성 전략을 구사하였으며, 이를 이용하여 플라즈마 질화 시스템을 한 예로 전력 흡수, 가스 유동, 전자 온도, 전자 밀도, 화학종의 분포를 분석하였다. 금속 노출형 안테나의 경우 전력 도입부 쪽에 전력 흡수의 불균형이 모델에서 예측되었으며 유전체피복 안테나의 한 예에서 전력 흡수 표피 깊이가 실제 보고된 값인 53 mm와 잘 일치하는 50 mm로 예측되었다. 또한 수소연료 전지 분리판을 위한 고속 질화 공정용 시스템의 모델링에서도 산업용 대량 처리 시스템에 적절한 다중 분리판의 장입 간격을 가스 유동, 활발한 질화종인 질소 원자와 질소 분자 이온의 농도를 근거로 예측하였다.

• 한국해양공학회지
• /
• 제25권6호
• /
• pp.60-65
• /
• 2011

A low temperature plasma carburizing process was performed on AISI 316L austenitic stainless steel to achieve an enhancement of the surface hardness without degradation of its corrosion resistance. Attempts were made to investigate the influence of the processing temperatures on the surface hardened layer during low temperature plasma carburizing in order to obtain the optimum processing conditions. The expanded austenite (${\gamma}_c$) phase, which contains a high saturation of carbon (S phase), was formed on all of the treated surfaces. Precipitates of chromium carbides were detected in the hardened layer (C-enriched layer) only for the specimen treated at $550^{\circ}C$. The hardened layer thickness of ${\gamma}_c$ increased up to about $65{\mu}m$ with increasing treatment temperature. The surface hardness reached about 900 $HK_{0.05}$, which is about 4 times higher than that of the untreated sample (250 $HK_{0.05}$). A minor loss in corrosion resistance was observed for the specimens treated at temperatures of $300^{\circ}C{\sim}450^{\circ}C$ compared with untreated austenitic stainless steel. In particular, the precipitation of chromium carbides at $550^{\circ}C$ led to a significant decrease in the corrosion resistance. A diamond-like carbon (DLC) film coating was applied to improve the wear and friction properties of the S phase layer. The DLC film showed a low and stable friction coefficient value of about 0.1 compared with that of the carburized surface (about 0.45). The hardness and corrosion resistance of the S phase layer were further improved by the application of such a DLC film.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권11호
• /
• pp.1604-1608
• /
• 2000

Penicillin antibiotics such as penicillin G, ampicillin and amoxicillin have been widely used in the pig industry to control salmonellosis, bacterial pneumonia, and urinary tract infections. Extensive use of antibiotics in veterinary clinics has resulted in tissue residues and bacterial resistance. To prevent unwanted drug residues entering the human food chain, extensive control measures have been established by both government authorities and industries. The demands for reliable, simple, sensitive, rapid and low-cost methods for residue analysis of foods are increasing. In this study, we established a rapid prediction test for the detection of pigs with unacceptable tissue residues of penicillins. The recommended therapeutic doses of three penicillins, penillin G (withdrawal time, 7 days), ampicillin (withdrawal time, 7 days) and amoxicillin (withdrawal time, 14 days), were administered to three groups of 20 pigs each. Blood was sampled before drug administration and during the withdrawal period. The concentration of penicillins in plasma, determined by a semi-quantitative ELISA, were compared to that of internal standard, 4 ppb, which corresponded to the Maximum Residue Limit in milk. The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine whether drug residues in pig tissues were negative or positive. That is, a B/Bs ratio less than 1 was considered residue positive, and larger than 1 negative. All 60 plasma samples from pigs were negative to three penicillins at pretreatment. Penicillin G could be detected in the plasma of the treated pigs until day 4 post-treatment and ampicillin until day 2, whereas amoxicillin could be detected until day 10 of its withdrawal period. The present study showed that the semi-quantitative ELISA could be easily adapted to detect residues of penicillin antibiotics (penicillin G, ampicillin and amoxicillin) in live pigs.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권12호
• /
• pp.1775-1778
• /
• 2000

Oxytetracycline has been widely used in the cattle industry to control pneumonia, shipping fever, foot rot, bacterial enteritis, and uterine infections. Extensive use of antibiotics in veterinary clinics has resulted in residues in tissue and bacterial resistance to antibiotics. To prevent unwanted drug residues from entering the human food chain, extensive control measures have been established by both government authorities and industries. The demands for reliable, simple, sensitive, rapid and low-cost methods for residue analysis of foods are increasing. In this study, we established a rapid test for tissue residues of oxytetracycline in cattle. The recommended therapeutic dose of oxytetracycline (withdrawal time, 14 days) was administered to 10 cattle. Blood samples were collected from each cow before drug administration and during the withdrawal period. The concentration of oxytetracycline in plasma, determined by a semi-quantitative ELISA, was compared to that of the internal standard, 10 ppb. The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine whether the residues in cattle tissues were negative or positive. That is, a B/Bs ratio less than 1 was considered as residue positive and that greater than 1 as negative. Based on this criterion, all plasma samples from cattle were negative to oxytetracycline at pre-treatment. Oxytetracycline could be detected in the plasma treated cattle until day 14 post-treatment. The present study showed that the semi-quantitative ELISA could be easily adapted in predicting tissue residues for oxytetracycline in live cattle.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권4호
• /
• pp.528-534
• /
• 2000

Sixteen specific pathogen free 4-wk-old crossbred weanling pigs were allotted into a $2{\times}2$ factorial design to evaluate chromium picolinate (CrPic) on growth and physiological responses. Two factors included (1) no Cr or 400 ppb Cr supplementation from chromium picolinate and (2) lipopolysaccharide (LPS) injection on day 21 (d 21) and 35 (d 35) compared to saline application. Plasma samples and rectal temperature were obtained from all piglets before (h 0) and at 2 h (h 2), 4 h (h 4), 8 h (h 8), and 24 h (h 24) after LPS injection ($200{\mu}g/kg$ BW, intraperitoneally). The rectal temperature on d 21 was significantly decreased (p<0.05) of about $0.36^{\circ}C$ with Cr supplementation before LPS injection. After LPS injection, the daily gain of piglets was decreased during d 35-38. Supplementation of Cr had no effect in general on growth performance particularly after LPS injection. The plasma glucose, triglycerides and urea nitrogen concentrations were changed in different ways after LPS injection. Plasma cortisol level was significantly elevated at h 2 after LPS injection on d 21 and d 35. The supplementation of Cr in the diet can delayed plasma cortisol release on d 35. The results suggest that 400 ppb Cr supplementation from CrPic may modulate the physiological response during immune stress in weanling pigs.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.942-945
• /
• 1999

In this work, we proposed Proper etching algorithm for ultra-large scale integrated circuit device and simulated etching process using the proposed algorithm in the case of ICP (inductive coupled plasma) 〔1〕source. Until now, many algorithms for etching process simulation have been proposed such as Cell remove algorithm, String algorithm and Ray algorithm. These algorithms have several drawbacks due to analytic function; these algorithms are not appropriate for sub 0.1 ${\mu}{\textrm}{m}$ device technologies which should deal with each ion. These algorithms could not present exactly straggle and interaction between Projectile ions and could not consider reflection effects due to interactions among next projectile ions, reflected ions and sputtering ions, simultaneously In order to apply ULSI process simulation, algorithm considering above mentioned interactions at the same time is needed. Proposed algorithm calculates interactions both in plasma source region and in target material region, and uses BCA (binary collision approximation4〕method when ion impact on target material surface. Proposed algorithm considers the interaction between source ions in sheath region (from Quartz region to substrate region). After the collision between target and ion, reflected ion collides next projectile ion or sputtered atoms. In ICP etching, because the main mechanism is sputtering, both SiO$_2$ and Si can be etched. Therefore, to obtain etching profiles, mask thickness and mask composition must be considered. Since we consider both SiO$_2$ etching and Si etching, it is possible to predict the thickness of SiO$_2$ for etching of ULSI.