• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.400-400
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• 2012

산화물 반도체는 넓은 에너지갭을 가지고 높은 이동성과 높은 투명성을 가지기 때문에 초고 속 박막 트랜지스터(Thin film transistor; TFT)에 많이 응용되고 있다. 그러나 ZnO 및 $In_2O_3$ 산화물 반도체를 박막트랜지스터에 사용할 경우 소자가 불안정하여 전기적 성질이 저하되고 문턱전압의 이동이 일어난다. TFT에 사용되는 산화물 반도체로는 GaInZnO, ZrInZnO, HfInZnO 및 GaSnZnO의 전기적 특성에 관한 연구가 많이 되었다. 그러나 titanium-indium-zinc-oxide (TIZO) TFT에 대한 연구는 비교적 적게 수행 되었다. 본 연구에서는 TFTs의 안정성을 향상하기 위하여 TFT의 채널로 사용되는 TiInZnO를 형성하는데 간단한 제조 공정과 낮은 비용의 용액 증착방법을 사용하였다. 졸-겔 전해액은 Titanium (IV) isopropoxide $[Ti(OCH(CH_3)_2)_4]$, 0.1 M Zinc acetate dihydrate $[Zn(CH_3COO)_2{\cdot}2H_2O]$ 그리고 indium nitrate hydrate $[In(NO_3)_3{\cdot}xH_2O]$을 2-methoxyethanol의 용액에 합성하였다. $70^{\circ}C$에서 한 시간 동안 혼합 하였다. Ti의 몰 비율은 10%, 20% 및 40% 로 각각 달리하여 제작하였다. $SiO_2$층 위에 2,500 rpm 속도로 25초 동안 스핀 코팅하여 TFT를 제작하였다. TIZO 박막에 대한 X-선 광전자 스펙트럼 관측 결과는 Ti 몰 비율이 증가함에 따라 Ti 2p1/2피크의 세기가 증가함을 보여주었다. TiZO 박막에 Ti 원자를 첨가하면 $O^{2-}$ 이온이 감소하기 때문에 전하의 농도가 변화하였다. 전하 농도의 변화는 TiZO 채널을 사용하여 제작한 TFT의 문턱전압을 양 방향으로 이동 하였으며 off-전류를 감소하였다. TiZO 채널을 사용하여 제작한 TFT의 드레인 전류-게이트 전압 특성은 on/off비율이 $0.21{\times}107$ 만큼 크며 이것은 TFT 소자로서 우수한 성능을 보여주고 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3494-3499
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• 2009

The stability of omeprazole in the aqueous solutions containing loxoprofen or Sodium bicarbonate was examined at room temperature. Loxoprofen or Sodium bicarbonate (60 mg) was added to omeprazole (600 ${\mu}g$/ml) solution to check the stability profile. Then, the solution was kept at room temperature for 80 hours. The concentration was assayed at each concentration by stability-indicating High performance liquid chromatography (HPLC) method. Aliquots of the solution were withdrawn at specified time intervals and assayed by chromatographic analysis for intact omeprazole. The relation between omeprazole concentration and peak area was linear from 5 to 160 ${\mu}g$/ml. The analysis method was precise with relative standard deviation (% RSD) no greater than 3.05 %. The remaining percentage-time curves revealed that omeprazole was degraded rapidly as functions of time and temperature following pseudo first-order kinetics. In conclusion, the stability of omeprazole was significantly affected by liquid solutions mixed with alkalizer (Sodium carbonate) or the NSAIDs (loxoprofen).

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.39-47
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• 2015

In this study, the properties of strength and drying shrinkage of alkali-activated slag cement (AASC) with magnesium oxide (MgO) contents between 0 and 16 wt% were investigated. The ground granulated furnace blast slag (GGBFS) was activated by potassium hydroxide (KOH) and dosage of activator was 2M and 4M. The MgO was replaced with 2% to 16% of GGBFS by weight. The water-binder ratio (w/b) was 0.5. In the result, the higher MgO content leads to a slightly higher degree of reaction and thus to a higher compressive strength at all ages. The compressive strength and ultra sonic velocity (UPV) increased with increases MgO contents. The drying shrinkage of AASC was decreased as the contents of MgO increases. The results from SEM confirmed that there were densified reaction product of higher MgO content specimens.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.574-578
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• 1998

Electrochemical Ion Exchang(EIX) electrode containing Amberlite IRP-64 as a cation ion exchange resin and Stylene-Buthylene-Rubber(SBR) as a binder was fabricated by the compressed diecasting method. The adsorption and elution characteristics in copper sulfate solution were investigated at the various electrode potentials and electrolyte pHs. In the adsorption process, it was found that the maximum adsorption rate of copper was obtained at -1800 mV and the ratio of adsorption was 92% during 90 min. In the elution process, the elution rate of copper was increased in proportion to anodic potential in the present experimental range and the ratio of elution was 88% during 50 mins at 3600 mV. The adsorption and elution processes were significantly affected by the variation of local pH in the vicinity of electrochemical ion exchange electrode. The higher performances of adsorption and elution were elution were obtained at basic and acidic eletrolytes.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.735-742
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• 1996

Polymeric matrices were prepared with dextran and silver sulfadiazine by adding glycerine as a plasticiser. Namely, the release rate of the drug from the polymeric matrix formulations in dissolved phases was determined in a phosphate buffer solution. The results were as follows : The drug release time was delayed as drug loading contents increased, whereas it decreased as the glycerine concentration increased. The drug release time was not changed with varying the molecular weight of the dextran. The apparent release rate constant (k) increased as the composition of silver sulfadiazine and glycerine was increased. But the apparent release rate constant (k) was not changed with increasing molecular weight of the dextran.

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.49-55
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• 2014

Characteristics of sedimentation of dredged soil is depended on the field condition and characteristics of dredged soil because dredged fill ground was formed by various field condition, sedimentation and self-weight consolidation process of dredged soil. Dredged fill ground is formed as separated sedimentary layer by characteristics of dredged soil. Therefore, it requires some special test method to consider a various field condition, characteristics of sedimentation and self-weight consolidation of dredged soil. In this study, in order to identify the characteristics of sedimentation of dredged soil with disposing velocity geo-centrifuge test and laser particle size analyzer were performed. As a results, river and mixed dredged soil show the separation sedimentation by soil particle size. And sedimentation of clayey dredged soil is parallel to the bottom surface of dredged fill space.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.7-12
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• 2017

Recovery of sulfuric acid is very important after biomass converted to sugar by acid hydrolysis. In this work, the separation of sulfuric acid from sulfuric acid/glucose solution was studied by electrodiaysis. Three chamber method, which requires both anion membrane and cation membrane, is the most commonly used in the electrodialysis process, but two chamber method using only an anion membrane was the focus of this study. Sulfuric acid was perfectly separated from a mixture of 10~30 wt% glucose and 1~3 M sulfuric acid by electrodialysis using two chamber method. The separation rate of sulfuric acid lineary increased with higher current density when the affect of diffusion and convection of the membrane was small. Without electric energy, 45% of sulfuric acid was separated by diffusion and convection only.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.581-587
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• 1988

The solvolysis of substituted benzyl bromides was studied in binary solvent mixtures of acetone-water and ethanol-water at $25^{\circ}C$ and $45^{\circ}C$. The rate constants increase with electron-donating substituents in benzene ring and increasing of water contents in both of solvent mixtures. The sensitivity parameter (m) of the solvolysis of substituted benzyl bromides to solvent ionizing power (Y) was decreased in going from the electron-donating group to electron-withdrawing one, whereas their nucleophilic sensitivity increased continuously in going to above same substituents. It was shown that electron-donating (electron-withdrawing) groups make the transition state looser (tighter). The above results were consisted with the account for the potential energy surface model and the quantum mechanical approach.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.46-53
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• 2016

It is required to predict a limit cycle amplitude controlled by system's nonlinear behavior as well as an eigen-frequency and initial growth rate of instabilities under the linear motions, in order to fully understand combustion instabilities in a lean premixed gas turbine combustor. Special focus of the current work is placed on the limit cycle amplitude prediction using flame describing function(FDF) where the ratio of a heat release fluctuation to a given flow perturbation is expressed as a function of frequency and amplitude. In this study, the CFD modeling work based on RANS is carried out to obtain FDF, which makes that the nonlinear thermo-acoustic model is successfully developed for predicting the limit cycle amplitude of the combustion instability.

• Polymer(Korea)
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• v.26 no.1
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• pp.53-60
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• 2002

Polypropylene(PP : continuous phase)/poly (styrene-co-acrylonitrile)(SAN : dispersed phase) blends, and PP/poly(acrylonitrile-butadiene-styrene) (ABS : dispersed phase)blends, containing various amounts of compatibilizer(PP-SAN graft copolymer), were prepared at various shear rates by using twin-screw extruder. In the PP/SAN blend, the average size of the dispersed particles(SAN) was increased with SAN content, while the flexural strength and tensile strength were decreased with SAN content. When the screw rpm was increased from 10 to 60 rpm, the size of the dispersed phase was decreased while the flexural strength and the tensile strength were increased. Maximum mechanical strength and minimum droplet size were observed when the 5 phr compatibilizer was added to the PP/SAN blends. The mechanical strength of PP/ABS blends such as flexural strength and tensile strength increased by adding compatibilizer was reached maximum when blends contained 5 phr compatibilizer.