• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.221-221
• /
• 1999

산소 플라즈마의 음이온 발생 특성을 정전 탐침을 이용하여 관찰하였다. 탐침에 흐르는 음 전류는 전자 전류와 음이온 전류의 합으로 구성되며 음이온 속도는 전자 속도에 비해 작아 음이온의 발생 량이 증가함에 따라 음이온 전류의 크기는 감소하게 된다. 따라서 탐침에 흐르는 양 전류와 음전류의 비 Ii*/(Ie*+I-*)는 음이온의 발생량에 따라 변화하게 된다. 또한 플라즈마 전위와 부유 전위간의 전위차와 음 이온밀도와의 관계는 다음과 같은 관계식 e(Vp-Vf)/Te={3.35 + 0.5 ln$\mu$ - ln(ni/ne)]을 갖으며 이로부터 음이온의 밀도를 측정할 수 있다. 이들 두 가지 방법을 이용하여 정전 탐침에서 얻어지는 탐침 자료로부터 직접 플라즈마에서 음이온 발생에 관한 정성적인 특성 변화를 관찰할 수 있었다. 본 실험에서는 운전 압력(0.1-600mTorr)과 입력 전력(50-500W)에 따른 DC, ICP, CCP에서 발생하는 산소 음이온 플라즈마의 발생 특성을 분석하였다. 운전 압력이 증가함에 따라 음이온의 비율이 증가하다가 감소함이 관찰되었으며 400mTorr에서 최대 30%의 음이온 발생 비율을 갖음을 알 수 있었으며 더 큰 압력 하에서는 발생률이 점차 감소함을 관찰되었다. 또한 음이온의 발생 율은 입력 전력보다 운전 압력에 민감하게 변화하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.562-562
• /
• 2013

산소 플라즈마는 음이온을 발생시키는 음전성 플라즈마로서 감광제 세정이나 금속, 폴리실리콘 등의 식각을 위해 할로겐 가스와 혼합하여 반도체나 디스플레이 공정에 광범위하게 사용되고 있다. 산소 플라즈마는 아르곤 플라즈마와 그 특성이 상이하고, 다량의 음이온이 국부적으로 만들어지므로 음이온의 공간분포 진단이 중요하다. 본 연구에서는 평판형 부유형 탐침에 고조화파 분석법을 적용하여 양이온의 밀도를 구하고, 직류 차단 커패시터를 제거하여 접지전위에서 전자 전류 측정을 통하여 위치에 따른 전자의 상대적인 공간 분포를 얻었다. 이러한 방법으로 측정된 양이온과 전자의 공간 분포로부터 음이온의 공간 분포를 구할 수 있었다. 가스 압력, 산소 첨가량, 인가 전력 등 여러 조건에서 측정된 음이온의 분포는 이론적인 경향성과 유사함을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.150.1-150.1
• /
• 2015

일부 금속들은 산화물을 형성하여 반도체적 성질을 갖게 되는데 이를 산화물 반도체라 한다. 산화물 반도체는 전자의 전도 특성에 의해 기존에 널리 사용되고 있는 a-Si 반도체 보다 뛰어난 전자 이동도를 갖고 넒은 Band gap energy를 갖기 때문에 누설 전류가 적어 Device 제작 시 저전력 구동이 가능하다는 장점이 있어 관련 연구가 활발히 진행 중이다. 산화물 박막을 증착하는 방법으로는 용액 공정, CVD, Sputtering 등이 있다. 그 중 Sputtering을 이용한 산화물 박막 증착 시 산소 음이온이 기판으로 가속하여 박막에 충돌, 박막 물성에 영향을 준다는 연구결과가 보고되고 있다. 본 연구에서는 Sputtering을 이용하여 ITO를 증착하는 과정에서 발생하는 산소 음이온을 측정하는 장치를 개발하여 산소 음이온 발생여부를 확인해 보았다.

• Journal of the Korean Vacuum Society
• /
• v.9 no.4
• /
• pp.428-435
• /
• 2000

Negative ion generation in an inductively coupled oxygen plasma was investigated by using a Langmuir probe. It was observed that the probe current ratio of the positive ion saturation current and the negative current which is consisted of the electron current and the negative ion current, and also the potential difference between the floating potential and plasma potential vary with the RF input power and more sensitively with the operating pressure, respectively. Results show that the operating condition to achieve the maximum probe current ratio and the minimum potential difference shift from the low pressure region to the high pressure regions with increasing the input power. It implies that the generation of the negative oxygen ions increases and the recombination of the positive and negative ions are enhanced in the plasma.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.4
• /
• pp.246-250
• /
• 2014

This study was carried out to investigate the anion-distribution of the famous valleys in Jeollanam-do. Sampling sites were the valley region of Eochi, Surak, Daeheungsa and Namchang. The maximum values of the anion level were 11,190~178,100 ea/mL at each site and the highest value was measured at the Surak. The mean values showed 14,060 ea/mL in Surak, 8,590 in Eochi, 8,420 in Daeheungsa and 7,020 in Namchang. For a day, the highest Concentration showed in the 5:00 a.m to 7:00 a.m and the lowest values showed in the 12:00 p.m to 14:00 p.m. According to the distance from the source, the anion tended to disappear within 7 m in Namchang and Daeheungsa. But, it influenced by 50 m in Eochi and Surak. Correlation coefficient was -0.54 with wind speed, 0.34 with humidity about the formation of anion. There was no significant correlation with wind speed in the island and longevity village where we had studied in 2009 and 2011. But there was similar correlation with humidity in the island region. Therefore, we can say that wellbeing life is walking around the valley early in the morning with no wind.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.8-8
• /
• 2010

본 발표에서는 OLED, LCD, E-ink 등에 적용되는 고품질 전도성 투명 산화막의 구조, 전기적 성질, 광학적 성질, 표면 거칠기 등에 미치는 공정 변수의 영향을 유연 기판 적용 사례를 들어서 설명한다. 특히 RF superimposed dc sputtering 방법으로 성장시킨 TCO의 특성이 현재 알려진 어떤 방법보다도 우수한 특성들과 유연 기판에 필수적인 내절성을 갖는 결과를 보여주고 있음에 주목하고 그 원리 및 대형화 가능성에 대해서 언급한다. 증착된 박막의 투습성 평가에서 측정 장비의 한계치 이하를 달성하였고 플라즈마를 이용한 중간 처리 과정의 효과로 PC, PET 등의 필름 기판에서도 우수한 성질을 갖는 박막의 성공적인 증착이 이루어 졌음을 설명한다. 여기에는 적절한 산소 분압의 유지가 관건이며 이미 재료연구소에서는 대형 타겟 시스템에 대해서 안정된 공정을 운영하고 있다. RF superimposed dc power의 특징은 타겟에서 반사되는 고속 중성 입자의 유속을 적절하게 제어할 수 있다는 점으로 판단되며 이는 주로 산소 원자와 산소 음이온의 에너지가 높다는 점에 주목할 필요가 있다. Carcia등의 보고에 따르면 산소 음이온의 경우에는 110 eV가 넘는 운동 에너지를 가지고 성장 중인 박막에 입사하여 결함을 생성한다고 한다. 이들 고속 입자들의 에너지를 낮추고 그 수를 감소시킬 수 있는 방법 중의 하나가 RF superimposed dc라고 판단된다.

• Tuberculosis and Respiratory Diseases
• /
• v.41 no.1
• /
• pp.11-19
• /
• 1994

Background: Mycobacterium tuberculosis is a facultative intracellular pathogen which persists and multiplies within macrophage. Competent cell mediated immunity by cooperation of both T lymphocyte and macrophage of the host is required to kill the Mycobacterium tuberculosis. But a precise understanding of the pathogenesis of tuberculosis infection in pulmonary alveolar macrophage has not been achived. Research on the macrophage's basic microbicidal mechanism has elucidated the importance of oxygen-dependent or oxygen-independent components. Oxygen dependent processing begins with the reduction of oxygen by NADPH oxidase and generation of superoxide. In this study, the oxidative metabolic status of blood monocyte and pulmonary alveolar macrophage in patients with active pulmonary tuberculosis was accessed and compared with that of healthy control subjects to know whether there was a basic difference in superoxide generation by mononuclear cells between two groups. Methods: Pulmonary alveolar macrophage was purified after performing BAL(bronchoalveolar lavage) through the bronchi of infected lesion by plastic adhesion method. Blood monocyte was purified by Ficoll-Hypaque method. Superoxide generation by blood monocyte and pulmonary alveolar macrophage was measured by ferricytochrome-C reduction method after either stimulated with PMA(phorbol myristate acerate) or non-stimulated states. We also measured the effect of pulmonary tuberculosis patient's serum on superoxide generation by monocyte. Results: 1) Generation of superoxide by alveolar macrophage obtained from patients with pulmonary tuberculosis was little higher than those of controls, and PMA enhanced the generation of 2) Generation of superoxide by blood monocyte obtained from patients with pulmonary tuberculosis was little higher than those of control(p>0.05), and PMA more enhanced the generation of superoxide in patientswith pulmonary tuberculosis than those in controls(p<0.02). 3) Patient's serum enhanced the generation of superoxide by blood monocyte obtained from patients with pulmonary tuberculosis and controls, but not in the case of PMA stimulated blood monocyte. Conclusion: The present study suggest that the phenomenon of M.tuberculosis escape the microbicidal action of macrophage was not result of suppressed superoxide generation by blood monocyte and pulmonary alveolar macrophage, rather there might be a factor to stimulate the generation of superoxide by blood monocyte in pulmonary tuberculosis patient serum, but the comparision with effect of control's serum on superoxide generation needs further elucidation.

• Applied Chemistry for Engineering
• /
• v.20 no.6
• /
• pp.593-602
• /
• 2009

For a long time, there is much interest in the superoxide anion radical as one of reactive oxygen species (ROS) not only in the basic research field of chemistry and physics but also in the life science (or biotechnology). Recently, it is becoming ever more vital since the toxic property of nanomaterials as well as advanced oxidation processes (AOP) frequently employed for controlling pollutants are connected with the formation of superoxide anion radicals. Despite many researches on superoxide anion radical, the quantitative information of its presence and its detailed reaction mechanism in aqueous environments remains largely unclear, causing the controversy and confusion. In this review paper, we attempted to summarize the physicochemical property, mechanisms, and applications of superoxide anion radical. In addition, we briefly incorporated the important application of superoxide anion radical in AOP, nanomaterials, and life science (or biotechnology).

• Tuberculosis and Respiratory Diseases
• /
• v.40 no.1
• /
• pp.16-22
• /
• 1993

Background: The Microbicidal and cytotoxic activities of neutrophils are to a large extent dependent on a burst of oxidative metabolism which generates superoxide anion, hydrogen peroxide, and other reactive products of oxygen. The respiratory burst of PMN is initiated by intracellular calcium mobilization that follows immune or particular stimulation and is very sensitive to modulation by c-AMP or adenosine. Despite its antagonism against adenosine, earlier study has demonstrated potent theophylline inhibition of the PMN respiratory burst at variable ranges of blood concentrations of theophylline in the healthy normal volunteers and in the septic animals pretreated or early post-treated with aminophylline (AMPH) or pentoxifylline. However it is unclear whether theophylline inhibits the superoxide generation or not in the established human sepsis caused by acute pneumonia, as taking into consideration of the fact that full activation of neutrophils have occurred within minutes after the septic insult in the animal experiments. Methods: We measured the $O_2$ generation of peripheral arterial neutrophils obtained from 11 human septic subjects caused by acute pneumonia before and 1 hour after completion of continuous AMPH infusion. Patients were identified and studied within 48 hour of admission. All subjects were administered an intravenous loading and maintenance dose of AMPH. The generation of $O_2$ was measured at a discrete time point (60 min) by the reduction of ferricytochrome c.PMA (10 ${\mu}g/ml$) was used as a stimulating agent. PMNs were isolated at a concentration of $2{\times}10^6$ cells/ml. The arterial oxygen tension, blood pressure and heart rates were also checked to evaluate the systemic effects of AMPH in the acute pneumonia. Results: The mean serum concentration of AMPH at 60 minutes was $8.8{\pm}0.6{\mu}g/ml$. Sixty minutes after AMPH infusion the generatition of $O_2$ was decreased from $0.076{\pm}0.034$ to $0.013{\pm}0.004$(OD) (p<0.05) and from $0.177{\pm}0.044$ to $0.095{\pm}0.042$(OD) (p<0.01) in the resting and stimulated PMNs respectively. $PaO_2$ was not changed after AMPH infusion. Conclusion: AMPH may compromise host defense by significant inhibition of neutrophil release of superoxide anion and it had no effect on improving $PaO_2$ in the acute pneumonia.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2003.05a
• /
• pp.157-160
• /
• 2003

‘우리들은 공기를 먹고살고 있다.’ 라고 해도 금방 실감할 수 있는 사람은 적을 것이다. 하지만 공기는 생명에 불가결한 것이다. 공기를 마신다고 하는 것. 즉 산소를 취한다고 하는 것으로 우리들의 몸은 에너지를 보급하고 있다고 하는 것을 새롭게 인식해야 할 것이다.(중략)