• Carbon letters
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• 제2권3_4호
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• pp.192-201
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• 2001

The Carbon/Carbon composite was prepared from 3D carbon fiber preform and coal tar pitch as matrix precursor. In order to evaluate of ablative characteristics of the composite, liquid rocket system was employed Kerosene and liquid oxygen was used as propellants, operating at a nominal chamber pressure of 330 psi and a nominal mixture ratio (O/F) of 2.0. The results of an experimental evaluation were that high density composite exhibited high, while low density composites showed low erosion resistance. The erosion rate against heat flux was highly depended on the density of the materials. The morphology of eroded fiber showed differently according to collision angle with heat flux on the composite. The granular matrix which derived from carbonization pressure of 900 bar was more resistance to heat flux than well-developed flow type matrix.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1692-1696
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• 2008

In this paper, we characterize the mechanical properties of PCL strand which is made by oscillating nozzle for tissue engineering scaffold. In order to increase the mechanical properties of the PCL strand, we designed an oscillating nozzle system for the 3D plotting system. First, we check the effect of the nozzle speed (3 to 8 mm/sec), frequency (0 or 300 Hz) and the oscillating amplitude (0 or 100 V) on the diameter of the PCL strand. Second, we observe the effect of the frequency (0, 100, 200 and 300 Hz) and the oscillating amplitude (0, 50 and 100 V) on the mechanical property of PCL strand. The mechanical properties and surface morphology of PCL strand made by oscillating nozzle are compared with the PCL strand made by normal nozzle using Nano-UTM and SEM.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.563.2-563
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• 2001

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from the radiographic examination. This study was done to get more informations about the root and canal configuration of C-shaped root by 3-dimentionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Teeth had been extracted from periodontal problems with sound crown and root portion, including teeth with caries lesion limited crown portion only.(omitted)

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.554-554
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• 2001

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from the radiographic examination. This study was done to get more informations about the root and canal configuration of C-shaped root by 3-dimentionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Teeth had been extracted from periodontal problems with sound crown and root portion, including teeth with caries lesion limited crown portion only.(omitted)

• 한국응용과학기술학회지
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• 제25권3호
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• pp.404-409
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• 2008

The core-shell composite particles of inorganic/organic were polymerized by using styrene(St) as a shell monomer and potassium persulfate (KPS) as an initiator. We studied the effect of core-shell structure of silicone dioxide/styrene in the presence of an anionic surfactant sodium lauryl sulfate (SLS) and polyoxyethylene alky lether sulfate (EU-S133D). We found that when $SiO_2$ core/PSt shell polymerization was prepared on the surface $SiO_2$ particle, to minimize the coagulation during the shell polymerization, the optimum conditions were at concentration of $2.56{\times}10^{-2}mole/L$ SLS. The structure of core-shell polymer was confirmed by measuring the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of core-shell polymer particles by transmission electron microscope (TEM).

• Journal of Species Research
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• 제9권3호
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• pp.181-190
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• 2020

Monoraphidium subclavatum (FBCC-A409) of this study clustered in the same clade as Messastrum gracile strains in the 18S rDNA phylogeny. Compared to Messastrum gracile, Monoraphidium subclavatum did not form a colony, and the curvature of the cell was slightly curved or slightly crescent-shaped. This result means that the genus Monoraphidium is still based on the morphospecies concept, and was not monophyletic and not distinguishable as a separate genus. Two Stichococcus-like strains of this study (NIBRCL0000114567, NIBRCL0000114571) belong to Deuterostichococcus epilithicus and Pseudostichococcus monallantoides respectively in phylogenetic analysis using 18S rDNA sequences. These two species are consistent with recent research in the morphology and the genetic analyses using 18S and ITS rDNA sequences. We reported M. subclavatum, D. epilithicus, and P. monallantoides as newly recorded species in Korea.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1516-1522
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• 2014

A series of 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ surface treatments were applied to $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates. The $Li[Li_{0.2}Mn_{0.54}Co_{0.13}Ni_{0.13}]O_2$ substrates were synthesized using a co-precipitation method. Sample (a) was left pristine and variations of the 20 wt % $(NH_4)_2SO_4$ and 3 wt % $Al_2O_3$ were applied to samples (b), (c) and (d). XRD was used to verify the space group of the samples as R$\bar{3}$m. Additional morphology and particle size data were obtained using SEM imagery. The $Al_2O_3$ coating layers of sample (b) and (d) were confirmed by TEM images and EDS mapping of the SEM images. 2032-type coin cells were fabricated in a glove box in order to investigate their electrochemical properties. The cells were charged and discharged at room temperature ($25^{\circ}C$) between 2.0V and 4.8V during the first cycle. The cells were then charged and discharged between 2.0V and 4.6V in subsequent cycles. Sample (d) exhibited lower irreversible capacity loss (ICL) in the first charge-discharge cycle as compared to sample (c). Sample (d) also had a higher discharge capacity of ~250 mAh/g during the first and second charge-discharge cycles when compared with sample (c). The rate capability of the $Al_2O_3$-coated sample (b) and (d) was lower when compared with sample (a) and (c). Sample (d), coated with $Al_2O_3$ after the surface treatment with $(NH_4)_2SO_4$, showed an improvement in cycle performance as well as an enhancement of discharge capacity. The thermal stability of sample (d) was higher than that of the sample (c) as the result of DSC.

• 한국미생물·생명공학회지
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• 제41권1호
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• pp.88-95
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• 2013

Candida 바이오필름은 숙주조직과 의료기기의 표면에 자라는 자가-조직화된 미생물의 군락으로 전통적인 항진균제에 대한 저항성이 높게 나타난다. 황금(Scutellaria baicalensis)의 뿌리는 극동지방에서 의료용 목적으로 널리 사용되어 왔다. 본 연구의 목적은 10 C. albicans 임상 분리균주에 의해 형성된 바이오필름에 대한 황금의 수용성 추출물의 효과를 평가하고, 항바이오필름 활성에 대한 메커니즘을 알아보는 것이다. 바이오필름에 대한 효과는 XTT 환원분석법을 사용하였으며, 조사된 모든 균주에 대한 대사활성은 MIC에서 유의하게 감소($57.7{\pm}17.3$%)하였다. 황금추출물은 (1,3)-${\beta}$-D-글루칸 합성효소의 활성을 저해하였고 C. albicans의 형태에 대한 황금의 효과는 글루칸 합성의 억제로 인한 생장의 변화와 관련이 있었다: 대부분의 세포는 둥글고 팽창되었으며 세포벽이 진하게 염색되거나 파열되었다. 항캔디다 활성은 살진균성이었고, 황금은 C. albicans를 $G_0/G_1$기에 머물게 했다. 데이터는 황금이 목표가 되는 균류에 다중의 치명적인 효과를 내며, (1,3)-${\beta}$-D-글루칸 합성효소의 활성을 저해함을 통해 궁극적으로는 세포벽의 파열과 죽음에 이르게 한다는 것을 나타낸다. 따라서 황금은 바이오필름과 관련된 캔디다의 감염을 치료하고 제거하기 위한 항진균제 개발 후보 물질로서의 가능성을 가진다.

• Restorative Dentistry and Endodontics
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• 제27권4호
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• pp.421-431
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• 2002

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from radiographic examination. This study was done to get more informations about the root and canal configuration of C-shape root by 3-dimensionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Six photo images from occlusal, apical, mesial, distal, buccal, lingual directions and radiographic view were taken as preoperative ones to compare them with 3-D image. After crown reduction to the level of 1-2mm over pulpal floor was performed, teeth were stored in 5.25% sodium hypochlorite solution for the removal of pulp tissue and debris. They were cleaned under running water, allowed to bench dry and embedded in a self-curing resin. This resin block was serially ground with a microtome (Accutom-50, Struers, Denmark) and the image of each level was recorded by digital camera (FinePix S1-pro, Fuji Co., Japan). The thickness of each section was 0.25mm. Photographs of serial sections through all root canal were digitized using Adobe Photoshop 5.0 and then minimum thickness of open and closed sites were measured (open site is the surface containing occluso-apical groove closed site is oppsite). After dizitization using 3-D Doctor (Able software Corp, USA). 3D reconstruction of the outer surface of tooth and the inner surface of pulp space was made. Canal classsification of C-shaped roots was performed from this 3-D reconstructed image. The results were as follows : 1. Most C-shape rooted teeth showed lingual groove (28/30). 2 According to Vertuccis' calssification, type I, II, III, IV, VII were observed. but also new canal types suck as 2-3-2, 1-2-3-2. 2-3-2-1, 2-3-2-3 were shown. 3 There was little difference in minimum thickness on coronal and apical portions, but open site were thinner than closed site on mid portion. Conclusively, 3D reconstruction method could make the exact configurations of C-shape root possible to be visualized and analyzed from multi-directions. Data from minimum thickness recommend cleaning and shaping be more carefully done on dangerous mid portion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.112-112
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• 2009

In this study, the effect of a long post-deposition thermal annealing(600 and 1000 $^{\circ}C$) on the surface acoustic wave (SAW) properties of polycrystalline (poly) aluminum-nitride (AlN) thin films grown on a 3C-SiC buffer layer was investigates. The poly-AlN thin films with a (0002) preferred orientation were deposited on the substrates by using a pulsed reactive magnetron sputtering system. Experimental results show that the texture degree of AlN thin film was reduced along the increase in annealing temperature, which caused the decrease in the electromechanical coupling coefficient ($k^2$). The SAW velocity also was decreased slightly by the increase in root mean square (RMS) roughness over annealing temperature. However, the residual stress in films almost was not affect by thermal annealing process due to small lattice mismatch different and similar coefficient temperature expansion (CTE) between AlN and 3C-SiC. After the AlN film annealed at 1000 $^{\circ}C$, the insertion loss of an $IDT/AlN/3C-SiC/SiO_2/Si$ structure (-16.44 dB) was reduced by 8.79 dB in comparison with that of the as-deposited film (-25.23 dB). The improvement in the insertion loss of the film was fined according to the decrease in the grain size. The characteristics of AlN thin films were also evaluated using Fourier transform-infrared spectroscopy (FT-IR) spectra and X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) images.