• E2M - 전기 전자와 첨단 소재
• /
• 제10권5호
• /
• pp.481-486
• /
• 1997

This paper describes the anisotropic etching characteristics of Si in acqueous TMAH/IPA solutions. The etch rates of (100) oriented Si crystal planes decrease with increasing TMAH concentration and IPA concentration. Etchant concentration and etch temperature have a large effect on hillock density. Hillock density strongly increase with lower TMAH concentration and higher etch temperature. The etched (100) planes are covered by pyramidal-shaped hillocks below TMAH 15 wt.%, but very smooth surface is obtained TMAH 25 wt.%. The addition of IPA to TMAH solution leads to smoother surfaces of sidewalls etched planes. Undercutting ratio of pure TMAH solution is much higher than KOH. But, addition of IPA to TMAh the underrcutting ratio reduces by a factor of 3∼4. Therefore, acqueous TMAH/IPA solution is able to use as anisotropic etchant of Si because of full compability with IC fabrication process.

• 한국환경과학회지
• /
• 제7권6호
• /
• pp.827-831
• /
• 1998

Statistical $SO_2$ forecasting technique by multiple regression analysis was designed and developed to predict $SO_2$ concentration in Wonju City. $SO_2$ concentration data measured from air pollution monitoring system and meteorological factors data such as : wind speed, atmospheric stability, surface temperature, relative humidity and precipitation were used in Wonju City during the 1996~1997. As the results, correlation model for forecasting was well fitted with some parameters including minimum temperature, wind speed and the $SO_2$ concentration of the previous day.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1992년도 하계학술대회 논문집 B
• /
• pp.820-824
• /
• 1992

An accurate method for extracting both Si film doping concentration and front or back silicon-to-oxide fixed charge density of fully depleted SOI devices is proposed. The method utilizes the current-to-voltage and capacitance-to-voltage characteristics of both SOI NMOSFET and PMOSFET which have the same doping concentration. The Si film doping concentration and the front or back silicon-to-oxide fixed charge density are extracted by mainpulating the respective threshold voltages of the SOI NMOSFET and PMOSFET according to the back surface condition (accumulation or inversion) and the capacitance-to-voltage characteristics of the SOI PMOSFET. Device simulations show that the proposed method has less than 10% errors for wide variations of the film doping concentration and the front or the back silicon-to-oxide fixed charge density.

• 센서학회지
• /
• 제17권4호
• /
• pp.256-260
• /
• 2008

This paper describes the mechanical properties of poly(polycrystalline) 3C-SiC thin films with various doping concentration, in which poly 3C-SiC thin fil's mechanical properties according to the n-doping concentration 1($9.2{\times}10^{15}cm^{-3}$), 3($5.2{\times}10^{17}cm^{-3}$), and 5%($6.8{\times}10^{17}cm^{-3}$) respectively were measured by nano indentation. In the case of $9.2{\times}10^{15}cm^{-3}n$-doping concentration, Young's modulus and hardness were obtained as 270 and 30 GPa, respectively. When the surface roughness according to n-doping concentrations was investigated by AFM(atomic force microscope), the roughness of poly 3C-SiC thin films doped by 5% concentration was 15 nm, which is also the best of them.

• Architectural research
• /
• 제7권1호
• /
• pp.19-26
• /
• 2005

Unlike other countries, Korea uses various kinds of wall-paper as finishing material. Conventional wall-paper consists of paper and vinyl, and petrochemical ink is used for the decoration of the surface. Adhesive is used to paste the wall with the wall-paper, which emit substantial amounts of VOCs and formaldehyde. In this study, VOCs characteristics emitted from specimens made of concrete, mortar, gypsum board and wall-paper were investigated using small chamber method. Moreover, concentration and emission factor of BTEX(Benzene, Toluene, Ethylbenzene, m,p,o-Xylene) and TVOC were investigated, and concentration and emission factor decay were estimated. As a result of the prediction, both time-dependent concentration decay and cumulative concentration can be converted into the logarithmic scale. Furthermore, prediction equations were developed from the experimental results under accurately controlled experimental conditions. Therefore, there may be difference if the estimated equations are directly applied to real buildings. Further research should be done on the generalization of the developed prediction equations.

• 한국응용과학기술학회지
• /
• 제5권1호
• /
• pp.53-62
• /
• 1988

Properties of aqueous solution, that is, the viscosities and solubilities of benzene were observed in relation to critical micelle concentration of each alkyl aldehyde polyoxyethylene glycol acetal type surfactant. These showed that the mininum points in specific viscosity/concentration-concentration curves were corresponded with the critical micelle concentration obtained by surface tension and appeared the remarkable increase of non-Newtonics according to the increase of the number of carbon in hydrophobic groups. The fluidity of non-Newtonics is not observed by a little increase of the degree of polymerization in polyoxyethylene glycol groups.

• KSBB Journal
• /
• 제18권2호
• /
• pp.107-110
• /
• 2003

스텐트 재질인 stainless steel 표면에 모델 약물인 rose bengal을 포함한 생분해성 고분자 PLGA, PHB, MCL-PHA를 코팅하여 약물방출 특성을 조사하였다. PLGA의 농도가 낮을수록, rose bengal의 농도가 높을수록, dip-coating 시간이 길수록 약물방출이 증가하였으며, PHB > PLGA > MCL-PHA의 순서로 약물이 빨리 방출되었다. 이는 생분해성 고분자의 농도 및 종류, 약물의 농도, dip-coating 시간 등을 변화시켜 약물방출을 조절할 수 있음을 나타낸다.

• 한국환경과학회지
• /
• 제11권12호
• /
• pp.1299-1305
• /
• 2002

Thirty sediment samples of the <63${\mu}{\textrm}{m}$ fraction collected from the southwestern coast of Korea were analysed for their heavy metal (Fe, Mn, Cr, Co, Cu, Ni, Zn and Pb) concentration. The results show that sediment texture plays a controlling role on the total metal concentrations and their spatial distribution. A single lM HCl extraction procedure was used in order to assess the environmental risk of heavy metals in bottom sediments. The non-residual fraction was the most abundant pool for Mn and Pb in most samples, which means that this metals are highly avaliable in these sediments. Cr, Ni, Fe, Co, Zn and Cu were mainly associated with the residual fraction, suggesting that their concentrations are controlled significantly by transport processes with the fine particles as carriers from diffuse pollution source. Concentration enrichment ratios(CER) were calculated from the non-residual contents and their values allowed us to classify the sediments according to their environmental risk.

• 한국환경과학회지
• /
• 제6권4호
• /
• pp.335-350
• /
• 1997

Numerical simulations of photochemical air pollution (CBM: Carbon-Bond Mechanisms under a theoretical three-dimensional local wind system are carried to clarify the fundamental characteristics of the effects of local wind on photochemical air pollution. According to the AWS data of Pusan coastal area and KMA, the surface wind of Pusan during summertime showed a very remarkable land and sea breeze circulation. The ozone concentration distribution using local wind model showed that high ozone concentration zone near coastal area moved toward inland In the afternoon. This change implies a sea breeze Increases the ozone concentration, but a land breeze decreases it in Pusan coastal area.

• 한국의류학회지
• /
• 제28권7호
• /
• pp.1029-1036
• /
• 2004

The fragrant fabrics were prepared by treatment with eucalyptus microcapsules. 100% cotton fabric, 100% polyester fabric and 100% wool fabric were used as test specimens. Using pad-dry-cure method, microcapsules were attached on each specimen by acrylic binder under conditions of varying concentration. Surface property, stiffness, and air permeability of fragrant fabrics were evaluated. As increasing concentration of binder, add-on yield was increased. Add-on yield was decreased with increasing laundering cycle, especially in polyester fabric. As the concentration of binder was increased, the properties of stiffness and air permeability were decreased. Also it fumed out that pad-dry-cure method was not suitable to polyester fabric.