• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.103-107
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• 2000

Boron Phosphide films were deposited on the glass substrate at the low temperature, 55$0^{\circ}C$, by the reaction of B$_2$H$_{6}$ with PH$_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 50 $m\ell$/min for B$_2$H$_{6}$, 50 $m\ell$/min for PH$_3$ $m\ell$/min and 1.5 $\ell$/min for $N_2$. To investigate the annealing effect, the films were annealed for 1hour, 3hours in $N_2$ambient at 55$0^{\circ}C$ and tested. The deposition rate was 1000$\AA$/min and the refractive index of film was 2.6. The measurement of X-RD shows that the films have the preferred orientation of (1 0 1) and the intensity of the peak for (1 0 1) orientation decreases according to the annealing time. The data of VIS spectrophotometer proved that the films are transparent in the visible range and the maximal transmittance increases according to the annealing time; 75.49% for as-deposited, 76.71% for 1hr-annealed and 86.4 % for 3hrs-annealed. The measurement of AFM shows that the average surface roughness increases according to the annealing time; 73$\AA$ for as-deposited, 88.9$\AA$ for 1hr-annealed and 220$\AA$ for 3hrs-annealed. Also, The data of the secondary electron emission rate(Υ) shows that the secondary electron emission rate increases according to the annealing time; 0.317 for 1hr-deposited, 0.357 for 1hr-annealed and 0.537 for 3hrs-annealed. And, The measurement of FT-IR that the characteristic of transmittance in the infrared range was stabilized through annealing.ing.

• 한국세라믹학회지
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• 제47권5호
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• pp.401-406
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• 2010

For the lower-temperature preparation of calcium monoaluminate(CA, C:CaO, A:$Al_2O_3$) clinker which is hard to synthesize purely within its melting point, an equimolar hydrate was obtained and then used as a starting raw material of clinker burning. The hydrate was prepared from a mixture of waste oyster shell and industrial aluminium hydroxide by heating to $1200^{\circ}C$, grinding and mixing with water. The hydrate was composed of amorphous aluminium hydroxide and $C_3AH_6$(H:$H_2O$) formed by resolution-precipitation mechanism of the system C-A-H. By heating the hydrate, nearly pure and porous calcium monoaluminate clinker was formed at $1400^{\circ}C$ which is fairly lower temperature than that of its melting point. The formation of calcium monoaluminate was performed mainly by the reaction between amorphous alumina and $C_{12}A_7$ caused by the decomposition of $C_3AH_6$. The immediate and earlier formation of $C_{12}A_7$ seemed to be accelerated by not only high surface area and instability of the thermally decomposed hydrate but also the catalytic effect of water decomposed from the hydrate. The final calcium monoaluminate clinker was very porous because of the influence of highly porous shape of the thermally decomposed hydrate.

• Transactions on Electrical and Electronic Materials
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• 제5권1호
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• pp.1-6
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• 2004

Zinc sulfide is a semiconductor with wide band gap and high refractive index and hence promising material to be used as ARC on commercial silicon solar cells. Uniform deposition of zinc sulfide (ZnS) by using chemical bath deposition (CBD) method over a large area of silicon surface is an emerging field of research because ZnS film can be used as a low cost antireflection coating (ARC). The main problem of the CBD bath process is the huge amount of precipitation that occurs during heterogeneous reaction leading to hamper the rate of deposition as well as uniformity and chemical stoichiometry of deposited film. Molar concentration of thiorea plays an important role in varying the percentage of reflectance and refractive index of as-deposited CBD ZnS film. Desirable rate of film deposition (19.6 ${\AA}$ / min), film uniformity (Std. dev. < 1.8), high value of refractive index (2.35), low reflectance (0.655) have been achieved with proper optimization of ZnS bath. Decrease in refractive index of CBD ZnS film due to high temperature treatment in air ambiance has been pointed out in this paper. Solar cells of conversion efficiency 13.8 ％ have been successfully achieved with a large area (103 mm ${\times}$ 103 mm) mono-crystalline silicon wafers by using CBD ZnS antireflection coating in this modified approach.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.91-96
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• 1996

광반응을 이용하여 fibrinolytic 활성을 보이는 LK (lumbrokinase)를 생체재료인 PU (polyurethane) 표면에 고정화하는 방법에 관하여 연구하였다. 먼저 PU표면에 amino 작용기를 도입하기 위하여 side chain 작용기로 phenylazide 와 amino작용기를 갖는 AzPhPAL을 이용하였으며 광반응은 266nm 이상의 UV light을 약 1분간 조사시키는 방법을 이용하였다. LK를 amino작용기가 유도된 PU 표면에 공유결합시키기 위하여 amide결합 형성시 사용되는 수용성 carbodiimide인 EDC를 이용하였다. ESCA측정시, AzPhPAL으로 공유결합시킨 경우 반응하지 않은 PU표면에 비하여 N/C가 0.1717로, LK 고정시 S/C가 0.0043로 증가된것을 알 수 있었다. 이것으로부터 AzPhPAL과 LK가 PU표면에 공유결합된 것을 확인할 수 있었으며 static contact angle 측정으로 표면개질된 PU표면이 소수성에서 친수성으로 변화된 것을 확인 할 수 있었다. 또한 공유결합된 LK의 활성을 확인하기 위하여 fibrin plate test를 실시하였는데 그 결과 고정화된 후에도 LK의 활성이 존재함을 알 수 있었다.

• 한국진공학회지
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• 제20권3호
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• pp.176-181
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• 2011

$Y_{1-x}BO_3:Ce_x^{3+}$ 세라믹 청색 형광체를 고상 반응법을 사용하여 $Ce^{3+}$ 이온의 농도를 변화시키면서 합성하였다. 청색 형광체의 결정 구조, 표면 형상과 광학 특성은 각각 X-선 회절 장치(XRD), 주사전자현미경, 광여기 및 발광 분광기를 사용하여 측정하였다. XRD 결과로부터 합성된 모든 형광체 분말의 주 피크는 (401)와 ($31\bar{2}$)면에서 발생한 회절 신호이었다. 광학 특성의 경우에, $Ce^{3+}$ 이온의 농도비가 0.10 mol일 때 여기 스펙트럼은 243 nm에서 발생하였고, 469 nm에 피크를 갖는 최대의 청색 형광 스펙트럼이 관측되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.270.1-270.1
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• 2013

Zinc oxide (ZnO) is one of the most powerful materials for purifying organic pollutants using photocatalytic activity. In this study, we have introduced a novel method to design highly photoreactive flexible 3 dimensional (3D) ZnO nanocomposite [F-ZnO-m (m: reaction time, min)] by electrospinning and simple-step ZnO growth processing (one-step ZnO seed coating/growth processing). Significantly, the F-ZnO-m could be a new platform (or candidate) as a photocatalytic technology for both morphology control and largearea production. The highest photocatalytic degradation rate ([k]) was observed for F-ZnO-m at 2.552 h-1, which was 8.1 times higher than that of ZnO nanoparticles (NPs; [k] = 0.316 h-1). The enhanced photocatalytic activity of F-ZnO-m may be attributed to factors such as large surface area. The F-ZnO-m is highly recyclable and retained 98.6% of the initial decolorization rate after fifteen cycles. Interestingly, the F-ZnO-m samples show very strong antibacterial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) after exposure to UV-light for 30 min. The antibacterial properties of F-ZnO-m samples are more effective than those of ZnO NPs. More than 96.6% of the E. coli is sterilized after ten cycles. These results indicate that F-ZnO-m samples might have utility in several promising applications such as highly efficient water/air treatment and inactivation of pathogenic microorganisms.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.223.1-223.1
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• 2013

Since sapphire single crystal is one of the materials that have excellent mechanical and optical properties, the single crystal is widely used in various fields, and the demand for the use of substrate of LED devices is increasing rapidly. However, crystal defects such as dislocations and stacking faults worsen the properties of the single crystal intensely. When sapphire wafer of single crystal is used as LED substrate, especially, crystal defects have a strong influence on the characteristics of a film deposited on the wafer. In such a case quantitative assessment of the defects is essential, and the evaluation technique is now becoming one of the most important factors in commercialization of sapphire wafer. Wet etching is comparatively easy and accurate method to estimate dislocation density of single crystal because etching reaction primarily takes place where dislocations reached crystal surface which are chemically weak points, and produces etch pit. In the present study, the formation behavior of etch pits and etching time dependence were studied systematically. Etch pit density(EPD) analysis using optical microscope was also conducted and measurement uncertainty of EPD was studied to confirm the reliability of the results. EPDs and measurement uncertainties for 4 inch sapphire wafers were analyzed in terms of 5 and 21 points EPD readings. EPDs and measurement uncertainties in terms of 5 points readings for 4 inch wafers were compared by 2 organizations. We found that the average EPD value in terms of 5 points readings for a 4 inch sapphire wafer may represent the EPD value of the wafer.

• 한국염색가공학회지
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• 제19권3호
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• pp.26-36
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• 2007

This study was carried out to treat the aqueous solutions containing reactive dyes(RB19, RR120 and RY179) by the Ozone demand flask method and adsorption process using activated carbon fiber(ACF) which are one of the main pollutants in dye wastewater. Ozone oxidation of three kinds of the reactive dyes was examined to investigate the reactivity of dyes with ozone, competition reaction and ozone utilization on various conditions for single- and multi-solute dye solution. Concentration of dyes was decreased continuously with increasing ozone dosage in the single-solute dye solutions. Competition quotient values were calculated to investigate the preferential oxidation of individual dyes in multi-solute dye solutions. Competition quotients(CQi) and values of the overall utilization efficiency, ${\eta}O_3$, were increased at 40mg/l of ozone dosage in multi-solute dye solutions. ACF(A-15) has much larger specific surface area$(1,584m^2/g-ACF)$ in comparison with granular activated carbon adsorbent (F400, $1,125m^2/g-GAC$), which is commonly used, and most of pores were found to be micropores with pore radius of 2nm and below. It was found that RB19 was most easily adsorbed among the dyes in this study. In the case of PCP (p-chlorophenol) and sucrose, which are single component adsorbate, adsorption capacities of ACF(A-15) were in good agreement with the batch adsorption measurement, and saturation time predicted of ACF columns for these components was also well agreed with practically measured time. But in the case of reactive dyes, which have relatively high molecular weight and aggregated with multi-components, adsorption capacities or saturation time predicted were not agreed with practically measured values.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2384-2393
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• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.

• Elastomers and Composites
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• 제40권4호
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• pp.272-276
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• 2005

3-aminopropyltrimethoxysilane을 처리한 반응성 있는 유리표면 위에 'dirt-ball' 방법을 사용하여 $C_{70}$-금 나노입자 다중성막 필름을 자기조립하였다. 표면처리한 유리막을 $C_{70}$ 과 ${\omega}$-아미노기를 가진 금 나노입자를 포함하고 있는 용액속에 담그었다. 유기반응(아민화 반응)은 여러층으로 쌓인 다중성막 $C_{70}$-금 나노입자 필름을 용이하게 자기조립 할 수 있었다. $C_{70}$-금 나노입자 필름의 화학적 안정성은 산성용액에 필름을 담근후 흡수도의 변화를 측정함으로 조사되었다. 또한 나노입자 필름의 초음파적 안정성은 초음파 조건에 $C_{70}$-금 나노입자 필름을 노출하여 초음파를 조사 시킨후 고체 표면 위에 부분적인 탈착도의 변화와 작은 정도의 응집성이 일어남을 알 수 있었다.