• 보존과학연구
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• s.32
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• pp.99-112
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• 2011

The three-storied stone pagoda located in Seungansaji temple site consists mainly of medium to fine-grained biotite granite and granitic gneiss, and partly macrocrystalline gneiss, muscovite gneiss and gabbro. The surface of the stone pagoda is extensively colonized by lichen and moss due to surrounding trees and lawns, and severly deteriorated. Therefore, a comprehensive deterioration diagnosis has been carried out and conservation treatment was conducted in this study. For the conservation treatment, dry cleaning is performed throughout all the surface of the pagoda for naturally grown lichen and biological contaminants using a soft brush and wooden knife. Crustose lichen strongly adhere to the surface was removed by wet cleaning using distilled water. Also, protective railings were reinstalled to an appropriate height with taking the distance from the stone pagoda into account. Finally, the ground around the stone pagoda was repaired with clay sand, and dike was installed with a natural gradient to facilitate water drainage.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1111-1120
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• 1998

Spray Drying Absorber(SDA) system, where the combustion product gas is mixed with atomized limestone-slurry droplets and then the chemical reaction of $SO_2$ with alkaline components of the liquid droplets forms sulfates, has been widely used to eliminate $SO_2$ gas from coal fired power plants and waste incinerators. Liquid atomization is necessary because it can maximize the reaction efficiency by increasing the total surface area and dispersion angle of the alkaline components. First, numerical calculations using FLUENT are carried out to investigate $SO_2$ concentration distribution and thus to calculate $SO_2$ removal efficiency. So to attain the optimized spray conditions, then an electrostatic spraying system is set up and spray visualization is performed to show the effect of an electric field on overall droplet size. Next, the effect of an electric field on the concentrations of $SO_2$ is experimentally examined. Field strength is varied from -10 kV to 10 kV and configurations of conduction charging and induction charging are utilized. Consequently, the electrostatic removal efficiency of 501 increases about 30% with the applied voltage of ${\pm}10kV$ but is independent of polarity of the applied voltage. It Is also found that the conduction charging configuration results in higher efficiency of $SO_2$ removal that the induction charging configuration. Finally, the effect of slurry temperature on $SO_2$ removal is studied. The temperature influences on the electrostatic removal efficiency of $SO_2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1259-1263
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• 2004

In this paper, the optimum design of ultrasonic dry cleaning head was investigated. The transducer instead of mechanical dynamic structure was used to generate ultrasonic wave and the horn-shape amplifier was utilized to solve the energy decaying problem of ultrasonic wave with propagating it through the media. The analyses of ultrasonic wave and a fluid for the selected structure of a cleaning head were carried out using SYSNOISE and ANSYS simulators, respectively. Based on simulator results, the distance between a horn and the substrate of 4 mm and the horn diameter of 10 mm were determined to maximize the energy of ultrasonic waves. The cooling structure was also considered to reduce the heat from the transducer and the horn. The equivalent circuit for the fabricated horn was deduced from HP4194A impedance/gain/phase analyzer and the frequency of an ultrasonic wave of 20.25 kHz was confirmed using the parameters of the equivalent circuit.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.45-50
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• 2020

We investigated the Si_1-xGe_x surface properties when dry cleaning the films using NF₃ / H₂O remote plasma. After the dry cleaning process, it was found that about 80-250 nm wide bumps were formed on the SiGe surface regardless of Ge concentration in the rage of x = 0.1 ~ 0.3. In addition, effects of the dry cleaning processing parameters such as pressure, substrate temperature, and H₂O flow rates were examined. It was found that the surface bump is significantly dependent on the flow rate of H₂O. Based on these observations, we would like to provide additional guidelines for implementing the dry cleaning process to SiGe materials.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.169.2-169.2
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• 2013

본 연구에서는 gas를 이용한 PECVD 공법중 이온화 에너지가 높고 대면적 코팅이 용이한 Hybrid 코팅 장비에서 Linear Ion-Gun 이용하여 탄화수소 계열의 gas인 $C_2H_2$ 와 Si을 함유한 TMS (tetramethylsilane, $Si(CH_3)_4)$ gas를 이용하여 저마찰, 고경도 특성을 갖는 Si-DLC 코팅에 대한 연구를 수행하였다. Si-DLC 코팅에 앞서 전처리 공정으로 Linear Ion-Gun에 Ar gas를 주입하고 고전압의 DC 전원을 인가하여 제품 표면의 건식세정 및 표면 활성화를 진행 후, $C_2H_2$ 와 TMS gas를 Linear Ion-Gun에 주입하여 Si-DLC 코팅 공정을 진행하였다. Si-DLC 코팅시 $C_2H_2$ gas 주입량을 고정하고 TMS 가스 유량을 5~20sccm으로 조절하여 Si 함유량에 따른 Si-DLC 코팅막의 특성을 분석하였다. 이렇게 코팅된 Si-DLC의 박막 특성 분석으로 마찰계수 측정을 위해 ball-on-disk 타입의 tribometer를 사용하였으며, 박막 경도 측정은 Nano-indenter를 이용하여 분석을 진행하였다. 그 결과 Si을 포함하지 않는 DLC의 경우 마찰계수가 ~0.2를 가지는 반면, Si-DLC의 경우 Si 함유량이 약 1.5at%일 때, 마찰계수 ~0.04 저마찰의 우수한 특성을 지니며, 박막의 경도는 22[Gpa]로 고경도의 Si-DLC 코팅을 확인할 수 있었다.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.26-31
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• 2023

We investigated the impact of NF₃ / H₂O remote plasma dry cleaning conditions on the SiO₂ etching rate at different preparation states during the fabrication of ultra-large-scale integration (ULSI) devices. This included consideration of factors like Si crystal orientation prior to oxidation and three-dimensional structures. The dry cleaning process were carried out varying the parameters of pressure, NF₃ flow rate, and H₂O flow rate. We found that the pressure had an effective role in controlling anisotropic etching when a thin SiO₂ layer was situated between Si₃N₄ and Si layers in a multilayer trench structure. Based on these observations, we would like to provide further guidelines for implementing the dry cleaning process in the fabrication of semiconductor devices having 3D structures.

• Journal of Conservation Science
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• v.18 s.18
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• pp.63-74
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• 2006

All rock materials of the three storied stone pagoda in Seoakri were composed of light gray alkali granite with medium grained and developed with small mialolitic cavities. This stone pagoda is preserving almost archetype except the head part because there was repair work already. But, foundation, basement and roof rocks are serious state by microbial invasion such as lichens. Because there are tree and grass that cause direct effect to stone pagoda surrounding. Therefore, conservation treatment executed the primary dry cleaning and secondary wet cleaning treatment. Stone surface is partly not removed well such as lichens which part removed using cleansing device that use high temperature steam. Some treated part concrete and epoxy resin remove and retreatment with mixing talc and alkali granite powder to epoxy resin. Did color matching at mixing process of epoxy resin and fillers to properties with set the feel of a material. Also, drainage ditched to minimize inflow of rainwater fall from slope that is on the east of stone pagoda, tree and grass in stone pagoda surrounding wished to do remove and control occurrence of lichens hereafter minimizing moisture conteats.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.177.1-177.1
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• 2015

플라즈마 건식 식각공정은 반도체 공정에 있어 증착 및 세정 공정과 함께 중요한 공정중 하나이다. 기존 연구에서는 높은 식각 속도, 종횡비, 대면적에 대한 균일도 증가를 위하여 플라즈마 이온 밀도의 증가와 전자 온도를 감소시키기 위한 노력을 하고 있으며 플라즈마 식각분석 연구에서는 분광학 분석 기법을 활용하여 플라즈마에 의하여 활성화된 식각 가스와 박막 표면의 반응 메커니즘 연구가 진행 중에 있다. 그러나 지금까지의 플라즈마 식각연구에서는 플라즈마 식각 공정에서 발생되는 박막의 damage에 대한 연구는 전무하다. 본 연구에서는 플라즈마 식각과정에서 발생되는 박막 표면의 damage 연구를 위하여 Nano-indenter에 의한 분석 기법을 제시하였다. Nano-indentation 기법은 박막 표면을 indenter tip으로 직접 인가하여 박막 표면의 기계적 특성을 분석하고 이를 통하여 플라즈마에 의한 박막 표면의 물성 변화를 정량적으로 측정한다. 실험에서 플라즈마 소스는 Adaptively Coupled Plasma (ACP)를 사용하였고 식각 가스로는 HBr 가스를 주로 사용하였으며, 플라즈마 소스 파워는 1000 W로 고정 하였다. 연구 결과에 의하면 식각공정 챔버 내 압력이 5, 10, 15 및 20 mTorr로 증가함에 따라 TEOS SiO2 박막의 강도가 7.76, 8.55, 8.88 및 6.29 GPa로 변화되는 것을 측정하였고 bias power에 따라서도 다르게 측정됨을 확인하였다. 이 결과를 통하여 Nano-indentation 분석 기법을 활용하여 TEOS SiO2 박막의 식각공정의 변화에 따른 강도변화를 측정함으로써 플라즈마에 의한 박막 표면의 damage를 정량적으로 측정 가능함을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.150-156
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• 2009

The removal of tiny particles adhered to surfaces is one of the crucial prerequisite for a further increase in IC fabrication, large area displays and for the process in nanotechnology. Various cleaning techniques (wet chemical cleaning, scrubbing, pressurized jets and ultrasonic processes) currently used to clean critical surfaces are limited to removal of micrometer-sized particles. Therefore the removal of sub-micron sized particles from silicon wafers is of great interest. For this purpose various cleaning methods are currently under investigation. In this paper, we report on experiments on the cleaning effect of 100nm sized fluorescence particles on silicon wafer using the plasma shockwave occurred by femtosecond laser. The plasma shockwave is main effect of femtosecond laser cleaning to remove particles. The removal efficiency was dependent on the gap distance between laser focus and surface but in some case surface was damaged by excessive laser intensity. These experiments demonstrate the feasibility of femtosecond laser cleaning using 100nm size fluorescence particles on wafer.

• Journal of Environmental Science International
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• v.10 no.1
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• pp.59-64
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• 2001

The effect of major operating parameters in spray drying sorber(=SDS) for automatic control for the simultaneous removal of acidic and organic gaseous pollutants from solid waste incinerator was performed. The field experiment was carried out in pilot scale test for the quantification of major operating parameters of hydrophilic and the hydrophobic pollutants. The removal efficiencies of $SO_2$and HCI in the 5wt% slurry condition were being increased with the increase of the stoichiometric ration which is the molecular ratio of lime to the pollutant concentration, and with the decrease of inflow flue gas temperature in the pilot SDS reactor. The removal efficiency along the height of spray drying sorber was closely related to the temperature profile, and more than 90% of total removal efficiency was achieved in an absorption region. For the removal of acidic gas the optimum operating condition considering the economics and a stable operation is the 5wt% of slurry concentration, 1.2 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. For the organic gases of benzene and toluene the removal efficiencies were 20-60% which is much lower than that of acidic gas. The best removal efficiency was obtained at 1.5 of stoichiometric ratio and 25$0^{\circ}C$ of inflow flue gas temperature. The organic\`s removal efficiency along the height of spray drying sorber was quite different from that of acidic gas, that is, more than 60% of the total removal efficiency for benzene and 90% of the total removal for toluene were achieved in the dried adsorption region, which was formed at the lower or exit part of the reactor.