• Carbon letters
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• 제13권4호
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• pp.248-253
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• 2012

Dielectrophoretic filtering and alignment of single-walled carbon nanotubes (SWCNTs) were tested using deuterium oxide as a solvent. A solution of deuterium oxide-SWCNTs was dropped on top of a silicon chip and an ac electric field was applied between pre-defined electrodes. Deuterium oxide was found to be a better solvent than hydrogen oxide for the dielectrophoresis process with higher efficiency of filtering. This was demonstrated by comparing Raman spectra measured on the initial solution with those measured on the filtered solution. We found that the aligned nanotubes along the electric field were not deposited on the substrate but suspended in solution, forming chain-like structures along the field lines. This so-called pearl chain formation of CNTs was verified by electrical measurements through the aligned tubes. The solution was frozen in liquid nitrogen prior to the electrical measurements to maintain the chain formation. The current-voltage characteristics for the sample demonstrate the existence of conduction channels in the solution, which are associated with the SWCNT chain structures.

• 한국초전도ㆍ저온공학회논문지
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• 제13권4호
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• pp.5-9
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• 2011

We have fabricated the superconducting $MgB_2$/carbon fiber by physical vapor deposition method. Mg (Magnesium) and B (Boron) were simultaneously deposited on the carbon fiber using the RF-sputtering and thermal evaporation, respectively. To ensure the relatively high vapor pressure of Mg at the growth region and the subsequent phase stability of $MgB_2$ at the deposition temperature, inverted funnel-like guide made of Mg-foil was employed while one side of the guide were open for the sputtered B flux. Mg vapor pressure should be controlled precisely to secure the complete reaction. The $MgB_2$/carbon fiber showed a uniformly deposited thin layer with dense and well-formed grains. The $MgB_2$/carbon fibers in this study showed $T_c$~37.5K, $J_c$ ~ $2{\times}10^4\;A/cm^2$ in the 20K, 0T.

• Bulletin of the Korean Chemical Society
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• 제22권4호
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• pp.429-431
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• 2001

• 한국해양학회지:바다
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• 제14권1호
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• pp.56-62
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• 2009

남해 연안의 3개 내만역을 대상으로 전체 어류군집이 이용하는 유기물의 기원을 조사하기 위하여 잘피와 부착조류, 저서미세조류, 해조류, 습지식물, 부유입자유기물(식물플랑크톤), 습지식물(갈대) 그리고 육상기원 유기물 등 다양한 유래의 유기물에 대한 탄소안정동위원소 비(${\delta}^{13}C$) 값과 어류 체조직의 ${\delta}^{13}C$ 값을 비교 분석하였다. 연구해역에서 채집된 총 31종의 어류들이 가지는 ${\delta}^{13}C$C 값은 -16.2${\sim}$-8.3‰의 범위를 나타내어 잘피(-8.3${\pm}$1.9‰), 부착조류(-12.4 ${\pm}$0.6‰), 저서미세조류(-15.4${\pm}$1.6‰) 그리고 해조류(-16.0${\pm}$1.8‰)가 가지는 ${\delta}^{13}C$ 값에 상당하는 범위를 나타내었다. 또한 연구수역의 어류군집이 가지는 ${\delta}^{13}C$ 값(-12.9${\pm}$1.5‰)은 남해 외양역에서 채집된 어류(-17.3${\pm}$0.8‰)와 낙동강 수계에서 채집된 어류군집(-23.2${\pm}$1.6‰)이 가지는 값에 비하여 뚜렷히 높은 값을 보였다. 따라서 본 조사에서 얻어진 ${\delta}^{13}C$ 분석 결과들은 조사가 수행된 3개 내만역 어류군집은 만 자체의 자생기원 저서생산에서 유래한 탄소원에 주로 의존하고 있다는 것을 시사하였다.

• Korean Chemical Engineering Research
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• 제50권2호
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• pp.244-250
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• 2012

MEA(monoethanolamine)와 PZ(piperazine)를 함침한 성형 제올라이트 13X 흡착제를 이용하여 연소배가스 중 이산화탄소를 분리하고자 하였다. 이를 위해 MEA, PZ를 각각 30, 50, 70 wt%로 성형 제올라이트에 함침하였다. 함침된 성형 제올라이트 13X 흡착제에 대한 물성 평가를 위해 XRD, FT-IR, BET를 이용하였다. 이산화탄소 분리특성을 조사하기 위하여, 성형 제올라이트, MEA 함침 성형 제올라이트, PZ 함침 성형 제올라이트에 대하여 25, 50, $75^{\circ}C$에서 흡착능을 조사하였다. 아민 함침 성형 제올라이트 흡착제는 온도가 증가할수록 흡착능은 감소한다. 최종적으로 연소배가스의 배출온도인 $50^{\circ}C$에서 흡착능을 비교할 때, PZ가 함침된 성형 제올라이트는 성형 제올라이트보다 1.8배 그리고 MEA 함침된 성형 제올라이트보다 20배 이상의 이산화탄소 흡착능을 보였다.

• 약학회지
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• 제32권3호
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• pp.164-169
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• 1988

$^{13}C$ NMR chemical shifts for 18 ${\alpha}-susbstituted$ toluenes at high dilution in $CCl_4$ solution have been determined. Substituents are as follows: H, Me, Et, n-Pr, iso-Pr, Ph, F, Cl, Br, $NH_2$, NHMe, $NMe_2$, OH, OMe, OCOMe, $CO_2Me$, $CO_2Et$, CN. Those chemical shifts of the methylene carbon of the toluene and the ${\alpha}-carbon$ of the n-butane systems are correlated well. (r=.975, slope=.962)

• Advances in materials Research
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• 제13권3호
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• pp.211-220
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• 2024

Polylactic acid or polylactide (PLA) is a biodegradable thermoplastic that can be produced from renewable material to create various components for industrial purposes. In 3D printing technology, PLA is used due to its good mechanical, electrical, printing properties, environmentally friendly and non-toxic properties. However, the physical properties and excellent electrical insulation properties of PLA have limited its application. In this study, with the carbon black (CB) as filler added into PLA, the lattice spacing and morphology were investigated by using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The physical properties of PLA-carbon composite were evaluated by using tensile test, shore D hardness test and density and voids measurement. Impedance test was conducted to investigate the electrical properties of PLA-Carbon composites. The results demonstrate that the inclusion of carbon black as filler enhances the physical properties of the PLA-carbon composites, including tensile properties, hardness, and density. The addition of carbon black also leads to improved electrical conductivity of the composites. Better enhancement toward the electrical properties of PLA-carbon composites is observed with 1wt% of carbon black in N774 grade. The N550 grade with 2wt% of carbon black shows better improvement in the physical properties of PLA-carbon composites, achieving 10.686 MPa in tensile testing, 43.330 in shore D hardness test, and a density of 1.200 g/cm3 in density measurement. The findings suggest that PLA-carbon composites have the potential for enhanced performance in various industrial applications, particularly in sectors requiring improved physical and electrical properties.

• Corrosion Science and Technology
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• 제13권5호
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• pp.163-169
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• 2014

The corrosion resistance of epoxy-coated carbon steel was evaluated. The carbon steel surface was subjected to different treatment methods such as steel grit blasting and power tool treatment as well as contamination of water soluble salt. To study the effect of the surface treatments and contamination, the topology of the treated surface was observed by confocal microscopy and a pull-off adhesion test was conducted. The corrosion resistance of the epoxy-coated carbon steel was further examined by electrochemical impedance spectroscopy (EIS) combined with immersion test of 3.5 wt% of NaCl solution. Consequently, the surface contamination by sodium chloride with $16mg/m^2$, $48mg/m^2$ and $96mg/m^2$ didn't affect the adhesion strength for current epoxy coated carbon steel and blister and rust were not observed on the surface of epoxy coating contaminated by various concentration of sodium chloride after 20 weeks of immersion in 3.5 wt% NaCl aqueous solutions. In addition, the results of EIS test showed that the epoxy-coated carbon steel treated with steel grit blasting and power tool showed similar corrosion protection performance and surface cleanness such as Sa 3 and Sa 2.5 didn't affect the corrosion protectiveness of epoxy coated carbon steel.

• 공업화학
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• 제29권5호
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• pp.594-603
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• 2018

본 연구는 VOC 제거 기술인 TSA 공정에서 제올라이트 13X와 활성탄이 채워진 두 종류의 탑을 사용하여 원료농도, 질소 유량, 수증기 유량, 탑 온도 등 조업조건의 영향을 분석하였다. 본 연구의 TSA 사이클은 흡착단계, 수증기 탈착단계, 건조 및 냉각단계로 구성되었다. 2% 벤젠 농도에서 제올라이트 13X와 활성탄의 사이클 당 전체 흡착량은 각각 4.44 g과 3.65 g으로 활성탄보다 충전밀도가 큰 제올라이트 13X가 더 많은 양의 벤젠을 흡착할 수 있었다. 수증기 탈착의 결과에서 수증기 유량을 증가시키고 탑의 외부 가열로 온도를 높이면 탈착시간이 짧아지고 배출되는 벤젠의 농도가 높아지는 것으로 나타났다. 2% 벤젠 농도에서 수증기 유량을 75 g/hr로 증가시키면 탈착시간이 1 hr에서 최대 33 min까지 단축되어 상대적으로 건조 및 냉각단계의 시간이 늘어나 수증기 제거와 탑 냉각을 충분히 진행할 수 있었다. 탑 온도를 높이면 탈착량이 증가하나 $150^{\circ}C$ 이상에서는 에너지소비는 증가하는 반면 탈착량은 거의 일정했다. 연속 사이클 조업에서 재생단계 완료 시 잔존하게 되는 벤젠의 비율이 늘어나면 흡착제 working capacity 감소의 원인이 될 수 있다. 제올라이트 13X를 이용해 연속 사이클 공정실험을 수행한 결과 탑 내부에 잔존하는 벤젠의 비율이 4번째 사이클 이후 일정한 값으로 유지되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권3호
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• pp.24-35
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• 2019

It is known that ${\delta}^{13}C_{DIC}$ (carbon-13 isotope of dissolved inorganic carbonate (DIC) ions) of water increases when dissolved $CO_2$ degases. However, ${\delta}^{13}C_{DIC}$ could decrease when the pH of water is lower than 5.5 at the early stage of degassing. Laboratory experiments were performed to observe the changes of ${\delta}^{13}C_{DIC}$ as $CO_2$ degassed from three different artificial $CO_2$-rich waters (ACWs) in which the initial pH was 4.9, 5.4, and 6.4, respectively. The pH, alkalinity and ${\delta}^{13}C_{DIC}$ were measured until 240 hours after degassing began and those data were compared with kinetic isotope fractionation calculations. Furthermore, same experiment was conducted with the natural $CO_2$-rich water (pH 4.9) from Daepyeong, Sejong City. As a result of experiments, we could observe the decrease of DIC and increase of pH as the degassing progressed. ACW with an initial pH of 6.4, ${\delta}^{13}C_{DIC}$ kept increasing but, in cases where the initial pH was lower than 5.5, ${\delta}^{13}C_{DIC}$ decreased until 6 hours. After 6 hours ${\delta}^{13}C_{DIC}$ increased within all cases because the $CO_2$ degassing caused pH increase and subsequently the ratio of $HCO_3{^-}$ in solution. In the early stage of $CO_2$ degassing, the laboratory measurements were well matched with the calculations, but after about 48 hours, the experiment results were deviated from the calculations, probably due to the equilibrium interaction with the atmosphere and precipitation of carbonates. The result of this study may be not applicable to all natural environments because the pressure and $CO_2$ concentration in headspace of reaction vessels was not maintained constant as well as the temperature. Nevertheless, this study provides fundamental knowledge on the ${\delta}^{13}C_{DIC}$ evolution during $CO_2$ degassing, and therefore it can be utilized in the studies about carbonated water with low pH and the monitoring of geologic carbon sequestration.