• Journal of Environmental Science International
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• v.22 no.4
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• pp.407-413
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• 2013

The flow of sewage has been studied for hundreds of years. Reducing drag in pipes can allow sewer to be removed easily and quickly. Drag reduction is not only a macroscale issue. Physical and chemical properties of the nano-scale can affect flow at the macroscopic scale. In this paper the predictability of hydrophobicity at the nano-scale is studied. Molecular dynamics simulations were used to calculate the range of contact angles of water droplets in equilibrium on a pillared graphite surface. It was found that at a pillar height of two graphite layers there was the largest range of contact angles. It is observed that at this height the droplet begins to transition from the Wenzel state to the Cassie-Baxter state. Surfaces with larger pillar heights have much larger contact angles corresponding to a more hydrophobic surface. Silicon dioxide was also simulated in the water droplet. The contaminant slight decreased the contact angle of the water droplet.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.823-832
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• 2004

Atmospheric aerosol particles collected in Seoul on four single days, each in every seasons of 2001, were characterized and classified on the basis of their chemical species using low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA). Low-Z particle EPMA technique can analyze both the size and the chemical species of individual aerosol particles of micrometer size and provide detailed information on the size distribution of each chemical species. The major chemical species observed in Seoul aerosol were aluminosilicate, silicon dioxide, calcium carbonate, organic, carbon-rich, marine originated, and ammonium sulfate particles, etc. The soil originated species, such as aluminosilicate, silicon dioxide, and calcium carbonate were the most popular in the coarse fraction, meanwhile, carbonaceous and ammonium sulfate were the dominant species found in the fine fraction. Marine originated species such as sodium nitrate was frequently encountered, up to 30% of the analyzed aerosol particles.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.14-14
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• 2011

Graphene is known to possess excellent thermal properties, including high thermal conductivity, that make it a prime candidate material for heat management in ultra large scale integrated circuits. For device applications, the key parameters are the thermal expansion coefficient and the thermal conductivity. There has been no reliable experimental determination on the thermal expansion coefficient of graphene whereas the estimates of the thermal conductivity vary widely. In this work, we estimate the thermal expansion coefficient of graphene on silicon dioxide by measuring the temperature dependence of the Raman spectrum. The shift of the Raman peaks due to heating or cooling results from both the intrinsic temperature dependence of the Raman spectrum of graphene and the strain on the graphene film due to the thermal expansion mismatch with silicon dioxide. By carefully comparing the experimental data against theoretical calculations, it is possible to determine the thermal expansion coefficient. The thermal conductivity is measured by estimating the thermal profile of a graphene film suspended over a circular hole of the substrate.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.792-795
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• 1988

Titanium dioxide antireflection (AR) Coating, which is deposited on Si substrates using an organotitanium solution by the spinning technique, has been studied. The coated films on Si substrates were subsequently heated to $450^{\circ}C$. The thickness and index of refraction of films were varied continuousely from $740{\AA}$ to $1380{\AA}$ and from 1.7 to 2.1 respectively as a function of heat treatment temperature and time. Silicon solar cells AR-coated by the spinning technique showed as much as 31% improvement in conversion efficiency over the uncoated cell.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.164-169
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• 2008

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.3-3
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• 1996

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.41-42
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• 2015

The concrete aggregate generates carbon dioxide in production but its demanding is gradually increased in accordance with the depletion of natural resources. Therefore we evaluated compatibility and basic physical properties of Silicon manganese slag generated in iron production as an applicable concrete aggregate. In our test, the silicon maganese slag shows 2.8g/㎥ of density in 10mm of maximum particle size similar to a natural aggregate, and its absorption rate was 0.3% similar to the electric furnace slag. Unit volume weight and ratio of absolute volume was respectively 2,001㎏/㎥ and 51%. Strength properties of Silicon manganese slag will be evaluated with further studies and experiments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1991.10a
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• pp.63-67
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• 1991

Amorphous silicon films were deposited on glass, [100] single crystal silicon wafer with thermally grown silicon dioxide, and [100] silicon wafer substrates by Plasma Enhanced Chemical Vapor Deposition(with argon diluted silane source gas). Growth rate, UV optical band edge, and the hydrogen quantity in the amorphous silicon films have been investigated as a function of the preparation conditions by measuring film thickness, UV-absorbency, and FT-IR transmittance. The growth rate of the ${\alpha}$-Si:H films increases with increasing substrate temperture, flow rate and R.F. power density. The UV optical band edge shifts to blue with the increases in the deposition pressure. Increasing substrate temperature shifts the UV optical band edge of the films to red. Hydrogen quantity in the ${\alpha}$-Si:H films increases with an increases in the R.F. powr and decreases with an increase in the substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.199-199
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• 2008

이 실험은 NVM의 Oxide, Nitride, Oxide nitride층별 blocking, trapping and tunneling 속성에 대해서 밝히고자 한다. gate 전극은 값싸고 전도도가 좋은 알루미늄을 사용한다. 유리기판위에 Silicon nitride층을 20nm로 코팅하고 Silicon dioxide층을 10nm로 코팅한다. 그리고 amorphous Silicon material이 증착된다. Poly Silicon은 Solid Phase Crystallization 방법을 사용하였다. 마지막 공정으로 p-doping은 ion shower에 의한 방법으로 drain과 source 전극을 생성하였다. gate가 biasing 될 때, p-channel은 source와 drain 사이에서 형성된다. Oxide Nitride Oxide nitride (ONO) 층은 각각 12.5nm/20nm/2.3nm의 두께로 만들었다. 전하는 Program process 중에 poly Silicon층에서 Silicon Oxide nitride tunneling층을 통하여 움직이게 된다. 그리고 전하들은 Silicon Nitride층에 머무르게 된다. 그 전하들은 erasing process 중에 trapping 층에서 poly Silicon 층으로 되돌아 간다. Silicon Oxide blocking층은 trapping층으로 전하가 나가는 것을 피하기 위하여 더해진다. 이 논문에서 Programming process와 erasing process의 Id-Vg 특성곡선을 설명한다. Programming process에 positive voltage를 또는 erasing process에 negative voltage를 적용할 때, Id-Vg 특성 곡선은 왼쪽 또는 오른쪽으로 이동한다. 이 실험이 보여준 결과값에 의해서 10년 이상의 저장능력이 있는 메모리를 만들 수 있다. 그러므로, NVM의 중요한 두 가지 성질은 유지성과 내구성이다.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.106-113
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• 1997

The thermal characteristics of two binary mixtures by sodium azide/manganese dioxide and ferric oxide, two ternary mixtures by sodium azide/silicon dioxide/manganese dioxide and ferric oxide were studied to obtain the basic data of gas-generating agents for air bags. The thermal reaction for all mixtures started at about $420^{\circ}C$, but the temperature at which the reaction rate reached a maximum was different with the states of samples. According to reaction results, nitrogen, nitrogen oxide and nitrogen dioxide were detected by GC-MS and so many kinds of new chemicals from sodium azide and metal oxide mixtures by XRD. NMS is considered as most stable and reasonable mixture for this types of gas-generating agents.