• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.309-309
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• 2011

알루미늄 합금은 경량성과 우수한 가공성, 내식성 등의 특성을 지니고 있고 구리나 아연, 마그네슘, 실리콘 등과 쉽게 합금화 가능하다. 또한 알루미늄과 그 합금은 자동차, 항공기, 건축물, 레저 그리고 가전용품의 재료로도 널리 사용되고 있다. 특히 Al에 Si을 소량 첨가하게 되면 내식성과 반사율이 향상되는 것으로 알려져 있다. 본 연구에서는 마그네트론 스퍼터링으로 Al, Al-Si 박막을 코팅하여 박막의 미세구조와 가시광선의 반사율을 관찰하였다. 시편은 Si wafer를 사용하였으며 알코올과 아세톤으로 각각 10분간 초음파 세척한 후 진공장비에 장착하여 Ar 분위기에서 glow discharge로 in-situ cleaning을 약 30분간 실시하였다. 시편청정이 끝나면 ~10-6 Torr 까지 진공배기를 실시하고 Ar 가스를 주입하여 2.5 mTorr로 진공도를 유지하면서 박막 코팅을 실시하였다. 기판-타겟의 거리는 12 cm로 고정 하였고 0.7, 1.5, 2.0 kW의 스퍼터링 파워와 외부 자기장의 변화에 따라 실험을 실시하였다. 순수한 Al 박막의 경우 외부 자기장 변화가 박막조직 변화에 영향을 주었으나 Si이 함유된 Al 합금 박막에서는 외부 자기장의 효과보다는 스퍼터링 전원의 세기가 박막 조직을 변화시키는 주된 공정변수였다. 박막의 반사율은 Si이 함유된 박막이 순수한 Al 박막보다 높았으며 스퍼터링 전원 세기가 증가할수록 반사율이 증가하는 경향성을 보였다. 이것은 Si을 Al에 첨가하여 스퍼터링 전원 세기를 최적화하는 것만으로도 치밀한 조직의 박막을 코팅할 수 있으며 높은 반사율을 갖는 박막을 코팅할 수 있음을 의미한다.

• Journal of Dental Anesthesia and Pain Medicine
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• v.19 no.3
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• pp.151-158
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• 2019

Background: This study aimed to examine whether the combination of low-dose ketamine and propofol in deep sedation is clinically useful in controlling the behavior in intellectually disabled patients who are typically extremely noncooperative during dental procedures. Methods: A total of 107 extremely noncooperative intellectually disabled adult patients were analyzed. In all patients, deep sedation was performed using either propofol alone (group P) or using a combination of propofol and 0.2 mg/kg or 0.4 mg/kg ketamine (groups PK0.2 and PK0.4, respectively). The procedures were performed in the order of insertion of nasal cannula into the nostril, attachment of mouth gag, and mouth cleaning and scaling. The frequency of patient movement during the procedures, mean arterial pressure, heart rate, peripheral oxygen saturation, recovery time, discharge time, and postoperative nausea and vomiting were examined. Results: The three groups were significantly different only in the frequency of patient movement upon stimulation during single intravenous injection of propofol and scaling. Conclusion: For propofol deep sedation, in contrast to intravenous injection of propofol alone, prior intravenous injection of low-dose ketamine (0.4 mg/kg) is clinically useful because it neither affects recovery, nor causes side effects and can suppress patient movement and vascular pain during procedures.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.325-334
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• 2023

Membrane bioreactor (MBR) provides the benefits on high effluent quality and construction cost without the secondary clarification. Despite of these advantages, fouling, which clogs the pore in membrane modules, affects the membrane life span and effluent quality. Studies on the laboratory scale MBR were focused on the control of particulate fouling, organic fouling and inorganic fouling. However, less studies were focused on the control of biofouling and microbial aspect of membrane. In the full scale operation, most MBR produces high effluent quality to meet the national permit of discharge regulation. In this study, the performance and microbial community analysis were investigated in two MBRs. As the results, the performance of organic removal, nitrogen removal, and phosphorus removal was similar both MBRs. Microbial community analysis, however, showed that Azonexus sp. and Propionivibrio sp. contributed to indirect fouling to cause the chemical cleaning in the DX MBR.

• Journal of the Korean Vacuum Society
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• v.14 no.1
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• pp.17-23
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• 2005

Glow discharge mass spectrometry(GDMS) was used to determine the impurity concentrations of the deposited Cu films and the 6N Cu target. Cu films were deposited on Si (100) substrates at zero substrate bias voltage and a substrate bias voltage of -50 V using a non-mass separated ion beam deposition method. Since do GDMS has a little difficulty to apply to thin films because of the accompanying non-conducting substrate, we have used an aluminum foil to cover the edge of the Cu film in order to make an electrical contact of the Cu film deposited on the non-conducting substrate. As a result, the Cu film deposited at the substrate bias voltage of -50 V showed lower impurity contents than the Cu film deposited without the substrate bias voltage although both the Cu films were contaminated during the deposition. It was found that the concentration change of each impurity in the Cu films by applying the negative substrate bias voltage is related to the difference in their ionization potentials. The purification effect by applying the negative substrate bias voltage might result from the following reasons: 1) Penning ionization and an ionization mechanism proposed in the present study, 2) difference in the kinetic energy of accelerated Cu+ ions toward the substrate with/without the negative substrate bias voltage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.603-608
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• 2018

Although the voltage-applied discharge method is most widely used in the semiconductor and display industries, periodic management costs are incurred because the method causes defects due to the absorption of ambient fine dust and causes emitter tip contamination due to the discharge. The emitter tip contamination problem is caused by the accumulation of fine particles in ambient air due to the corona discharge of the ionizer. Fuzzy ball generation accelerates the wear of the emitter tip and deteriorates the performance of the ionizer. Although a mechanical cleaning method using a manual brush or an automatic brush is effective for contaminant removal, it requires management of additional mechanical parts by the user. In some cases, contaminants accumulated in the emitter may be transferred to the wafer or product. In order to solve this problem, we developed an ionizer for a clean environment that can remove the pencil-type emitter tip and directly ionize the surrounding gas molecules using the tungsten wire located inside the ion tank. As a result of testing and certification by the Korea Institute of Machinery and Materials, the average concentration was $0.7572particles/ft^3$, the decay time was less than two seconds, and the ion valance was 7.6 V, which is satisfactory.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1489-1497
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• 2003

Aerosol charge neutralizers with various radioactive sources have been used to apply an equilibrium charge distribution to aerosols of unknown charge distribution. However, the performance of aerosol charge neutralizers is not well known, especially for highly charged particles. Measurements of highly charged particles are needed in air cleaning devices, e.g. electrostatic precipitator, bag filter with a pre-charger, and electrical cyclone. In this study, the particle charging characteristics of two different aerosol charge neutralizers were experimentally investigated for singly charged monodisperse particles and highly charged polydisperse particles. One has radioactive source of $^{85}$ Kr (beta source, 2 mCi) and the other has $^{210}$ Po (alpha source, 0,5 mCi). The air flow rate passing through each aerosol charge neutralizer was changed from 0.2 to 2.5 L/min. The results show that the charge distribution of singly charged monodisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer is well agreed with the Boltzmann equilibrium charge distribution at an air flow rate of 0.3 L/min, However, it deviates from the equilibrium charge distribution when the air flow rates are 0.6, 1,0, and 1,5 L/min, On the other hands, the effect of air flow rate is insignificant for the $^{210}$ Po aerosol charge neutralizer. The non-equilibrium character in charge distribution of highly charged polydisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer greatly depends on the air flow rate, however it is insensitive to the air flow rate for the $^{210}$ Po aerosol charge neutralizer.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.95-99
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• 2016

As the survey results of cultivation area, farmhouse, yield and income to clarify the effect of PO Film on Korean melon industry in Seongju region, the covering areas of PE film of Korea, Kyungsangbuk-do and Seongju-gun in 2014 were decreased 91.5%, 94.9% and 95.2% as to 2010. In contrary, the covering areas of PO film of Korea, Kyungsangbuk-do and Seongju-gun in 2014 were increased 342.5%, 500% and 825% as to 2010. The cultivation area and farmhouse in 2015 were decreased 8.8% and 11.9% than those in 2010. The yield and production in 2015 were 38.2% and 25.9% increased han those in 2010. The gross and net income in 2015 were 1.3 and 2.7 times increased than those in 2010. Finally, to change as PO film, the productivity will be increased. And cleaning work and noxious materials discharge will be decreased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.28-35
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• 2004

$N_2$ has been one of the most useful gases in industrial application, for example, plasma ashing, surface cleaning and decomposition of pollution gases. In order to clarify $N_2$ plasma properties and increase practical applications, many experimental and theoretical investigations have been carried out until now on. In this papa, we examined the characteristics of $N_2$ RF Plasmas using one-dimensional fluid model. $N_2$ plasmas showed a double-layer structure in both sheath regions as the power source voltage becomes higher. Generally, a double-layer structure should be showed in electro-negative plasmas, but not in electro-postive plasmas such as $N_2$ discharge. However, most electrons in $N_2$ plasmas lost their energy by many excitation reactions in the near of both electrodes where electron collisions were actively executed and such continuous reactions during an RF period made this structure strong with increase of the power source voltage. The dependence of $N_2$ plasma properties on pressure was also discussed.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.81-89
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• 2019

This study deals with a process for recovering hydrogen isotopes from fusion exhaust gas. The goal of this process is to remove impurities, maximally recover only pure hydrogen isotopes. Experiments using hydrogen and deuterium were conducted to confirm the possibility of the recovery of hydrogen isotopes. In the exhaust gas containing H₂, impurities was removed in the membrane process, and only pure H₂ was recovered. And the H₂ in the exhaust gas of the He-GDC(Glow Discharge Cleaning) process was recovered using a cryogenic adsorption process. In addition, HAZOP analysis was performed for qualitative risk assessment. For scenario analysis, the damage prediction ALOHA program was used to calculate the range of influence. Finally measures were sought to improve safety.

• Journal of The Korea Institute of Healthcare Architecture
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• v.24 no.2
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• pp.37-44
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• 2018

Purpose: This study investigates the influences of coughing direction and healthcare worker's location on the transport characteristics of coughed particles in airborne infection isolation room (AIIR), which is commonly called negative pressure isolation room, with a downward ventilation system. Methods: Computational Fluid Dynamics (CFD) was used to simulate the airflow and for tracing the behavior of particles. Results: The results show that the airflow pattern and coughing direction have a significant influence on the characteristics of particle dispersion and deposition. When healthcare workers are in the isolation room with the patient who is lying on the bed, it is recommended to be located far from the anteroom to reduce the exposures from infectious particles. And when the patient is lying, it is more effective in removing particles than when the patient is in Fowler's position. Although it is an isolation room that produces unidirectional flow, coughing particles can spread to the whole room and a large number of particles can be deposited onto patient, bed, side rails, healthcare worker, ceiling, floor, and sidewall. Implications: Following the patients' discharge or transfer, terminal cleaning of the vacated room, furniture, and all clinical equipment is essential. Also, it is necessary to establish detailed standard operating procedure (SOP) in order to reduce the risk of cross-contamination.