• Korean Journal of Materials Research
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• v.17 no.1
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• pp.31-36
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• 2007

Nanoimprint lithography (NIL) is a new lithographic method that offers a sub-10nm feature size, high throughput, and low cost. One of the most serious problems of NIL is the stiction between mold and resist. The antistiction layer coating is very effective to prevent this stiction and ensure the successful NIL results. In this paper, an antistiction layer was deposited by VSAM (vapor self assembly monolayer) method on silicon samples with FOTS (perfluoroctyltrichlorosilane) as a precursor for making an antistiction layer. A specially designed LPCVD (low pressure chemical vapor deposition) was used for this experiment. All experiments were achieved after removing the humidity. First, the evaporation test of FOTS was performed for checking the evaporation temperature at low pressure. FOTS was evaporated at 5 Tow and $110^{\circ}C$. In order to evaluate the temperature effect on antistiction layer, chamber temperature was changed from 50 to $170^{\circ}C$ with 0.1ml of FOTS for 1 minute. Good hydrophobicity of all samples was shown at about $110^{\circ}$ of contact angle and under $20^{\circ}$ of hysteresis. The surface energies of all samples calculated by Lewis acid/base theory was shown to be about 15mN/m. The deposited thicknesses of all samples measured by ellipsometry were almost 1nm that was similar value of the calculated molecular length. The surface roughness of all samples was not changed after deposition but the friction force showed relatively high values and deviations deposited at under $110^{\circ}$. Also the white circles were founded in LFM images under $110^{\circ}$. High friction forces were guessed based on this irregular deposition. The optimized VSAM process for FOTS was achieved at $170^{\circ}C$, 5 Torr for 1 hour. The hot embossing process with 4 inch Si mold was successfully achieved after VSAM deposition.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.176-177
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• 2013

Surface plasmon polaritons (SPPs) have attracted the attention of scientists and engineers involved in a wide area of research, microscopy, diagnostics and sensing. SPPs are waves that propagate along the surface of a conductor, usually metals. These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of conductor. In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties. In this papers, we studied theoretical and experimental extraordinary transmittance (T) and reflectance (R) of 2 dimensional metal hole array (2D-MHA) on GaAs in consideration of the diffraction orders. The 2d-MHAs was fabricated using ultra-violet photolithography, electron-beam evaporation and standard lift-off process with pitches ranging from 1.8 to $3.2{\mu}m$ and diameter of half of pitch, and was deposited 5-nm thick layer of titanium (Ti) as an adhesion layer and 50-nm thick layer of gold (Au) on the semiinsulating GaAs substrate. We employed both the commercial software (CST Microwave Studio: Computer Simulation Technology GmbH, Darmstadt, Germany) based on a finite integration technique (FIT) and a rigorous coupled wave analysis (RCWA) to calculate transmittance and reflectance. The transmittance was measured at a normal incident, and the reflectance was measured at variable incident angle of range between $30^{\circ}{\sim}80^{\circ}$ with a Nicolet Fourier transmission infrared (FTIR) spectrometer with a KBr beam splitter and a MCT detector. For MHAs of pitch (P), the peaks ${\lambda}$ max in the normal incidence transmittance spectra can be indentified approximately from SP dispersion relation, that is frequency-dependent SP wave vector (ksp). Shown in Fig. 1 is the transmission of P=2.2 um sample at normal incidence. We attribute the observation to be a result of FTIR system may be able to collect the transmitted light with higher diffraction order than 0th order. This is confirmed by calculations: for the MHAs, diffraction efficiency in (0, 0) diffracted orders is lower than in the (${\pm}x$, ${\pm}y$) diffracted orders. To further investigate the result, we calculated the angular dependent transmission of P=2.2 um sample (Fig. 2). The incident angle varies from 30o to 70o with a 10o increment. We also found the splitting character on reflectance measurement. The splitting effect is considered a results of SPPs assisted diffraction process by oblique incidence.

• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.437-443
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• 2005

A rapid, selective and sensitive reversed-phase HPLC method for the determination of a major metabolite of terfenadine, fexofenadine, in human serum was developed, validated, and applied to the pharmacokinetic study of terfenadine. Fexofenadine and internal standard, haloperidol were extracted from human serum by liquid-liquid extraction with acetonitrile and analyzed on a $Symmetry^{TM}$ C8 column with the mobile phase of 1% triethylamine phosphate (pH 3.7)-acetonitrile (67:33, v/v, adjusted to pH 5.6 with triethylamine). Detection wavelength of 230 nm for excitation, 280 nm for emission and flow rate of 1.0 mL/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^{3}$ factorial design using a fixed fexofenadine concentration (50 ng/mL) with respect to its peak area and retention time. In addition, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of 10-500 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of serum was 10 ng/mL, which was sensitive enough for the pharmacokinetic studies of terfenadine. The overall accuracy of the quality control samples ranged from 95.70 to 114.58% for fexofenadine with overall precision (% C.V.) being 3.53-14.39%. The relative mean recovery of fexofenadine for human serum was 90.17%. Stability studies (freeze-thaw, short-term, extracted serum sample and stock solution) showed that fexofenadine was stable during storage, or during the assay procedure in human serum. However, the storage at $-70^{\circ}C$ for 4 weeks showed that fexofenadine was not stable. The peak area and retention time of fexofenadine were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of fexofenadine in human serum samples for the pharmacokinetic studies of orally administered Tafedine tablet (60 mg as terfenadine) at three different laboratories, demonstrating the suitability of the method.

• Analytical Science and Technology
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• v.13 no.3
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• pp.291-296
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• 2000

The SIMFUEL which composition is similar to PWR nuclear spent fuels was dissolved with a acid digestion bomb. An analytical conditions of ICP-AES for the direct determination of molybdenum in the uranium matrices without separation process were investigated. Based on the effect of uranium on molybdenum intensity. the most optimum wavelengths of molybdenum were found to be 202.030 and 203.844 nm. However, the method of standard additions is applied to overcome the effects of changing background caused by analyzing the sample solutions containing high concentration of uranium and the standard calibration solutions. The relative error of two methods, direct and indirect measurements with cation exchange resin separation procedures, was less than 5%. Therefore it was possible for this procedure to directly measure molybdenum in uranium matrices without separation. And this method was also applied to the determination of several percent of molybdenum in a U-Mo alloy.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.45-50
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• 2018

The functional nanomaterials of fluorescent dye-doped silica nanoparticles(NPs) are applied to bio applications such as bio-labeling of DNA micro-array, and bio-imaging. Organic dye-doped fluorescent silica NPs exhibit excellent bio-compatibility, non-toxic, and highly hydrophilic properties. In this study, organic fluorescent dyes were dissolved in ethanol, and deionized(DI) water. Organic fluorescent dyes were physically adsorbed to silica NPs and chemically doped to silica NPs. The fluorescence characteristics(FLC) was investigated by UV lamp irradiation of 365 nm wavelength. As results, the FLC of dye-doped silica NPs exhibits better than dye-adsorbed silica NPs and the FLC was improved with the increase of concentration of doped-dyes. The fluorescent organic dyes were well dissolved in ethanol than DI water. The photostability of dye-doped silica NPs was superior than pure fluorescent organic dye. The FLC of optimized dye-doped silica NPs would be applied to agent of non-invasive fluorescence bio-imaging in live cell and in vivo.

• Korean Journal of Materials Research
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• v.12 no.6
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• pp.452-457
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• 2002

Titanium oxide films were prepared by RF reactive magnetron sputtering. The effect of sputtering conditions on structural and optical properties was investigated systemically as a function of sputtering pressure(5~20 mTorr) and $O_2/Ar$ flow ratio(0.08~0.4). The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. At low sputtering pressure and $O_2/Ar$ flow ratio, the films had preferred orientations along [101] and [200] directions. As the sputtering pressure and $O_2/Ar$ flow ratio increased, the intensity of the 101 and 200 diffraction peaks decreased gradually. The microstructure of the sputtered films showed the fine grain size (20nm~50nm) and columnar microcrystals perpendicular to the substrate. With increasing the sputtering pressure and decreasing $O_2/Ar$ flow ratio, the sputtered films showed the more porous columnar structure. XPS analysis showed that stoichiometric $TiO_2$ films were deposited at 7 mTorr sputtering pressure and 0.2 $O_2/Ar$ flow ratio. The results of the X-ray diffraction showed that all films had only the anatase $TiO_2$ phase. Ellipsometeric analysis showed that the refractive index increased from 2.32 to 2.46 as the sputtering pressure decreased. The packing density calculated using the refractive index varied from 0.923 to 0.976, indicating that $TiO_2$films became denser as the sputtering pressure decreased.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.713-718
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• 2009

Advanced industries-IT, BT, NT and ET are rapidly developing in 21 century. And the cement industry is becoming the principal factor in air pollution because of the creation of $CO_2$ during manufacturing. Also, the cement industry will be faced with a crisis due to the exhaustion of natural resources. In this study, nano cement by Bottom-up method of a chemical synthesis was developed. The generation of $CO_2$ during the plasticization process of cement manufacturing was avoided. The purpose was to produce building materials that have both high strength and durability as the high value-added growth engine industry of the 21 century. The nano cement was developed using hydrothermal synthesis. This is a method of mixing after ripening, by manufacturing the high density gel and low gel, which does not require special test equipment or pressure conditions to produce. Particle size, SEM, EDX, and porosity tests were conducted. This study investigated the compressive strength of concrete with various compositions. Specimens were tested for compressive strength at 3, 7, 14 and 28 days. The medium-sized (50% by weight) cement particles created by chemical synthesis were less than 168 nm. The compressive strength of the mortar prepared using this cement was 53.9 MPa. But it was judged that succeeding study will be necessary for development of nano building materials with high ability and economical analysis.

• Journal of The Korean Astronomical Society
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• v.49 no.1
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• pp.25-35
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• 2016

Multiple color selection techniques are successful in identifying quasars from wide-field broadband imaging survey data. Among the quasars that have been discovered so far, however, there is a redshift gap at 5 ≲ z ≲ 5.7 due to the limitations of filter sets in previous studies. In this work, we present a new selection technique of high redshift quasars using a sequence of medium-band filters: nine filters with central wavelengths from 625 to 1025 nm and bandwidths of 50 nm. Photometry with these medium-bands traces the spectral energy distribution (SED) of a source, similar to spectroscopy with resolution R ~ 15. By conducting medium-band observations of high redshift quasars at 4.7 ≤ z ≤ 6.0 and brown dwarfs (the main contaminants in high redshift quasar selection) using the SED camera for QUasars in EArly uNiverse (SQUEAN) on the 2.1-m telescope at the McDonald Observatory, we show that these medium-band filters are superior to multi-color broad-band color section in separating high redshift quasars from brown dwarfs. In addition, we show that redshifts of high redshift quasars can be determined to an accuracy of Δz/(1 + z) = 0.002 - 0.026. The selection technique can be extended to z ~ 7, suggesting that the medium-band observation can be powerful in identifying quasars even at the re-ionization epoch.

• Korean Journal of Veterinary Service
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• v.18 no.2
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• pp.113-123
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• 1995

The present study was conducted to investigate the prevalent characteristics of Fowl Typhoid and antibiotic susceptibility of Salmonella gallinarum isolated from 56 infective or dead chickens of 20 egg laying farms in Kyung Buk province during the period from August to December 1994. 1. Among 416, 000 chickens of 92 flocks in 20 egg laying farms, 17, 360 chickens of 31 flocks were died of Fowl Typhoid. 2. Salmonella gallinarum was isolated from 56 chickens in liver and spleen, and then blood of infective chickens was positive to Pullorum antigen. 3, In the survey of gross lesion of 56 chickens, 43 chickens(76.8%) were swelled at liver, 39(69.6%) were swelled at spleen, 12(21.4%) were changed with bronze, 3(5.4% ) were hemorrhagic in peritoneal cavity. 4. In transmission pattern, 4 farms were outbreaked the entrance of chicken house at first, but the others were outbreaked at various place. They were transmitted at right and left directions in flock. 5. 2 farms confirmed at the early stage of infection were eradicated by removing infective chickens and administrating antibiotics, but 18 farms at chronic stage were not. 6. The biochemical properties of 112 Salmonella gallinarum from chickens were generally identical to those of the referance, but H$_2$S was not productive, cellobiose was fermentive. 7 Minimum inhibitory concentration(MIC) of 20 isolates was performed by using 21 antibiotics, MICs of Amikacin(Ak), Gentamicin(Gm), Kanamycin(Km), and Tetracycline (Tc) were below 1.6 ug/ml, Ampicillin(Am), Furazolidone(Fu) and Neomycin(Nm) were below 3.1 ug/ml, Cephalothin(Ce), Cefazoline(Cf) and Chloramphenicol(Cm) were below 6.3 ug/ml, Nalidixic acid(Na), Polymyxin(Po) and Rifampicin(Rf) were below 12.5 ug/ml, Penicillin (Pm) was below 25 ug/ml, Colistin(Co) and Streptomycin(Sm) were below 50 ug/ml, Sulfamerazine(Sr) and Sulfamethazine (St) were below 200 ug/ml, Lincomycin(Lm) and Spiramycin(Sp) were below 400 ug/ml, Bacitracin(Ba) was below 800 ug/ml. 8. Among the 20 isolates, all(100%) of those were sensitive to Ak, Am, Ce, Cf, Cm, Fu, Gm, Km, Na, Nm, Po, Rf, Sr, St and Tc, but 6 isolates(30%) were resistent to Co, 20(100% ) to Ba, Lm, Pm, Sm, and Sp. The drug resistance patterns were simple which 6 strains were BaCoLmPmSmSp type, and 14 were BaLmPmSmSp type.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.298-301
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• 2003

생물학적 토양오염 복원기술은 산소와 영양염류를 오염토양에 공급하여 호기성 미생물의 대사작용을 자극함으로써 유류를 생분해 하는 방법으로 널리 사용되고 있다. 유류에 오염된 토양은 혐기성 상태인 경우가 대부분이기 때문에, 호기성 미생물을 이용하기 위해서는 충분한 산소를 공급하여야 하므로 운전비가 많이 드는 단점이 있다. 최근에는 혐기성 미생물을 이용하여 유류오염 토양을 정화하는 방법이 보고되고 있다. 혐기성 생분해 방법은 다소 분해 속도는 느리지만 산소를 공급하지 않기 때문에 경제적인 유류오염토양 복원 방법으로 주목받고 있다. 본 연구에서는 디젤을 사용하여 인위적으로 10000 mg/kg.TPH soil의 농도로 오염시킨 토양 50g을 100$m\ell$ 용적의 vial에 주입하고 하수처리장의 혐기성 소화조 슬러지를 15$m\ell$, 30$m\ell$을 주입하여 배양하였으며 TPH의 분해량과 CH$_4$ 및 $CO_2$ 발생량을 측정하였다. vial의 기상을 $N_2$가스로 치환함으로써 혐기성 상태가 되도록 하였으며, 35$^{\circ}C$에서 90일간 배양하였다. 그 결과, 슬러지를 주입하지 않은 대조군의 경우에는 TPH의 분해가 거의 없었지만, 슬러지를 주입한 경우에는 TPH(Total Petroleum Hydrocarbon)농도가 55% 제거된 것으로 나타났다. TPH의 분해는 CH$_4$ 및 $CO_2$ 발생량과 밀접한 상관관계를 보였다. 본 연구의 결과로부터 하수처리장의 혐기성 소화조 슬러지를 이용한 유류오염 토양의 복원 가능성을 확인할 수 있었다.양에서 유동 가능성이 있는 중금속만을 추출하였다. 분석실험은 토양의 Cd2+ 와 Pb2+를 대상으로 행하여졌으며, 여러 토양에서 추출 분석한 결과를 EDTA분석결과와 비교하였다. 실험결과, 중금속은 매우 신속하게 고분자 자성체와 결합하였고, 그 후 자성체를 외부 자장으로 모은 후 산으로 용해시키고, 결합된 중금속은 Graphite furnace AAS로 분석함으로써 빠르고 효율적으로 분석실험을 수행할 수 있음을 알 수 있었다. 한편, 실험에서 나타난 수치들을 비교 검토한 결과 토양 분석시 sandy soil에서는 자성체를 이용한 분석이 EDTA에 의한 방법보다 더 높은 추출도를 보인 반면, silt 함량이 많은 토양의 경우에서 EDTA분석에서 더 높은 중금속 추출도를 보였다.s 중에서 490nm와 555nm의 복합밴드를 포함하는 OC2 알고리즘(ocean color chlorophyll 2 algorithm)을 사용하는 것이 OC2 series 및 OC4 알고리즘보다 좋은 추정 값을 도출할 수 있을 것으로 기대된다.환경에서는 5일에서 7월에 주로 이 충체의 유충이 발육되고 전파되는 것으로 추측되었다.러 가지 방법들을 적극 적용하여 금후 검토해볼 필요가 있을 것이다.잡은 전혀 삭과가 형성되지 않았다. 이 결과는 종간 교잡종을 자방친으로 하고 그 자방친의 화분친을 사용할 때만 교잡이 이루어지고 있음을 나타내고 있다. 따라서 여교잡을 통한 종간잡종 품종육성 활용방안을 금후 적극 확대 검토해야 할 것이다하였다.함을 보이고 있다.X> , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서