• Carbon letters
• /
• 제2권2호
• /
• pp.99-104
• /
• 2001

Partial mesophase (PM) pitch precursor was prepared from fluidized catalytic cracking-decant oils (FCC-DO) by chemical reaction in the presence of $Br_2$. The PM pitch heated-treatment at $420^{\circ}C$ for 9 h exhibited the softening point of $297^{\circ}C$ with 23% yield, and 55% anisotropic content. The PM pitch precursor was melt-spun through circular nozzle by pressurized $N_2$, stabilized at $310^{\circ}C$, carbonized at $700^{\circ}C$, $1000^{\circ}C$, and $1200^{\circ}C$. The enough stabilization introduced 16.4% of the oxygen approximately. The stacking height ($L_{c002}$) and interlayer spacing ($d_{002}$) of the as-spun fibers were 4.58 nm and $3.45{\AA}$ and the value became minimum and maximum at $700^{\circ}C$ respectively in the carbonization procedure. The tensile strength increased with an increase in the heat treatment temperature exhibiting highest value of 750 MPa at $1200^{\circ}C$ carbonization.

• 미생물학회지
• /
• 제35권3호
• /
• pp.205-210
• /
• 1999

Vibrio cholerae 는 사람에게 설사를 일으키는 병원성 세규닝며 본 연구에 이용된 V.cholerae KNIH002 는 국내의 설사질환 환자로부터 분리하였다. 콜레라 독소 검출용 프라이머를 이용하여 PCR 로 증폭한 산물을 탐침자로 이용하여 Southern hybridization을 실시한 결과 PstI 및 BglII로 이중절단된 4.5-kb 절편내에서 ctx 유전자가 존재함을 확인하였다. 따라서 염색체 DNA를 PstI 및 BglII로 절단 후 V. cholerae KNIH002 의 유전자 mini-libraries를 제조하였다. 그리고 동일 탐침자를 이용하여 colony hybridization을 실시한 결과 제조된 유전자 mini-libraries 로부터 신호를 나타내는 한 개의 클론을 선발하였다. 선발된 클로닝 지니는 플라스미드를 pCTX75 라 명명하였으며, 이 클론은 CHO 세포에 대한 세포 독력이 나타남을 확인하였다. 염기서열을 결정한 결과 클로닝된 플라스미드에는 ace 와 zot 유전자들은 각각 ATG 개시코돈과 TGA 종결코돈을 포함하여 291 bp와 1,200 bp 로 구성되어져 있었다. ace 유전자의 염기서열은 V.cholerae E7946 EI Tor Ogawa strain 이 것과 100% 일치하였다. 그러나 zot 유전자의 염기서열 및 아미노산 서열은 V. cholerae 395 Classical Ogawa strain 의 것과 각각 99% 및 98.8% 의 상동성을 보였다. 특히, V.cholerae 395 Classicale Ogawa strain 의 Zot 폴리펩타이드에서 100번, 272번, 281번째 alanine 은 V.cholerae KNIH002에서 모두 valine 으로 치환되어져 있었다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 춘계학술대회 논문집
• /
• pp.155-158
• /
• 2009

본 연구에서는 Hydroxy Terminated Polyether(HTPE) 추진제 원료와 HTPE 둔감 추진제 조성 2종에 대하여 DSC와 TGA를 사용하여 열분해 특성을 고찰하였고, Extermely Insensitive Detonating Substance(EIDS) 완속가열 시험을 수행하여 반응 시간과 반응 온도를 측정하였다. AN이 포함된 HTPE 002는 약 $125^{\circ}C$에서 AN의 상전이과정($II{\rightarrow}I$)을 거친 후, 약 $200^{\circ}C$범위까지 BuNENA와 AN이 함께 발열특성을 가지고 분해됨을 알 수 있었다. EIDS 완속가열 시험을 수행한 결과 HTPE 001은 $250^{\circ}C$, HTPE 002는 $152^{\circ}C$ 부근에서 반응이 있어났으며, 두 추진제 모두 $115^{\circ}C$부근에서 급격한 온도 상승이 일어났다.

• 한국정보통신학회논문지
• /
• 제14권3호
• /
• pp.691-698
• /
• 2010

본 연구에서는 RF magnetron sputtering 법으로 AZO 세라믹 타켓 ($Al_2O_3$ : 3 wt%)을 이용하여 Eagle 2000 유리 기판위에 기판온도 ($100{\sim}500^{\circ}C$)와 공정압력 (10 ~ 40 mTorr)에 따른 AZO 박막을 제작하여, 결정화 특성과 전기적 및 광학적 특성을 조사하였다. 모든 AZO 박막은 육방정계구조를 가지는 다결정 이었고, (002)우선 배향성이 관찰되었다. 기판온도 $300^{\circ}C$, 10 mTorr에서 제작한 AZO 막에서 가장 우수한 (002) 배향성을 나타냈으며, 이때의 반가폭 값은 $0.42^{\circ}$였다. 전기적 특성은 기판온도 $300^{\circ}C$, 10 mTorr에서 가장 낮은 비저항 $2.64{\times}10^{-3}\;{\Omega}cm$과 우수한 캐리어 농도 및 이동도를 $5.29{\times}10^{20}\;cm^{-3}$, $6.23\;cm^2/Vs$를 나타내었다. 모든 AZO 박막은 가시광 영역에서 80%의 투과율을 나타내었으며, 기판온도 증가와 공정압력 감소에 따른 Al 도핑효과의 증가로 밴드 갭이 넓어지는 Burstein-Moss 효과가 관찰 되었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제52권8호
• /
• pp.319-324
• /
• 2003

AIN thin films are deposited on Si (100) and $SiO_2$/Si substrates by using an RF magnetron sputtering method and by changing the conditions of deposition variables, such as RF power, $N_2$/Ar flow ratio, and substrate temperature ($T_sub$). For all the deposited AIN films, XRD Peak patterns are monitored to examine the effect of deposition condition on the crystal orientation. Highly (002)-oriented AIN films are obtained at following nominal deposition conditions; RF Power : 350W, $N_2$/Ar ratio = 10/20, T$_{sub}$ : $250^{\circ}C$, and working pressure = 5mTorr, respectively. AIN-based SAW devices are fabricated using a lift-off method by varying the thickness of AIN layer. Insertion losses and side-lobe rejection levels of fabricated SAW devices are extracted from their frequency response characteristics, which are also compared in terms of AIN thickness and substrate. Relationships between the film properties of AIN films and the frequency responses of SAW devices are discussed. It is concluded from the experimental results that the (002)-preferred orientation as well as the surface roughness of AIN film may play a crucial role of determining the device performances of AIN-SAW devices.s.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제5C권3호
• /
• pp.97-101
• /
• 2005

ZnO thin films were grown at different plume-substrate (P-S) angles of 90$^{\circ}$ (on-axis PLD), 45$^{\circ}$ and 0$^{\circ}$ (off-axis PLD) using pulsed laser deposition. The x-ray diffraction pattern exhibiting a dominant (002) and a minor (101) peak of ZnO indicates all films were strongly c-axis oriented. By observing of (002) peak, the FWHMs of ZnO (002) peaks decreased and c-axis lattice constant approached the value of bulk ZnO as P-S angle decreased. Whereas the carrier concentration of ZnO thin film deposited at P-S angle of 90$^{\circ}$ was ~ 10$^{19}$ /cm$^{3}$, the Hall measurement of ZnO thin films deposited at P-S angles of 0$^{\circ}$ and 45$^{\circ}$ was impossible due to the decrease of the carrier concentration by the improvement of stoichiometry and crystalline quality. By decreasing P-S angle, the grain size of the films and the UV intensity investigated by photoluminescence (PL) increased and UV peak position showed red shift. The improvement of properties in ZnO thin films deposited by off-axis technique was due to the decrease of repulsive force between a substrate and the particle in plume and the relaxation of supersaturation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
• /
• pp.3-6
• /
• 2009

Aluminum nitride (AIN) thin films were deposited on a polycrystalline 3C-SiC intermediate layer by a pulsed reactive magnetron sputtering system. Characteristics of the AIN/SiC heterostructures were investigated by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The columnar structure of AIN thin films was observed by FE-SEM. The surface roughness of AlN films on the 3C-SiC buffer layer was measured using AFM. The XRD pattern of AlN films on SiC buffer layers was highly oriented at (002). Full width at half maximum (FWHM) of the rocking curve near (002) reflections was $1.3^{\circ}$. The infrared absorbance spectrum indicated that the residual stress of AIN thin films grown on SiC buffer layers was nearly negligible. The 3C-SiC intermediate layers are promising for the realization of nitride based electronic and mechanical devices.

• 센서학회지
• /
• 제16권6호
• /
• pp.462-466
• /
• 2007

Aluminum nitride (AlN) thin films were deposited on Si substrates by using polycrystalline (poly) 3C-SiC buffer layers, in which the AlN film was grown by pulsed reactive magnetron sputtering. Characteristics of grown AlN films were investigated experimentally by means of FE-SEM, X-ray diffraction, and FT-IR, respectively. The columnar structure of AlN thin films was observed by FE-SEM. X-ray diffraction pattern proved that the grown AlN film on 3C-SiC layers had highly (002) orientation with low value of FWHM (${\Theta}=1.3^{\circ}$) in the rocking curve around (002) reflections. These results were shown that almost free residual stress existed in the grown AlN film on 3C-SiC buffer layers from the infrared absorbance spectrum. Therefore, the presented results showed that AlN thin films grown on 3C-SiC buffer layers can be used for various piezoelectric fields and M/NEMS applications.

• BMB Reports
• /
• 제30권1호
• /
• pp.80-84
• /
• 1997

The synthesis and secretion of human angiogenin in E. coli by the natural leader sequence has been studied. We constructed a recombinant plasmid containing human angiogenin cDNA which encompassed all the coding region including leader sequence required for secretion. The recombinant plasmid was introduced into a suitable E. coli host. The angiogenin was detected in the culture medium and periplasm upon the induction of gene expression. The molecular weight of the secreted angiogenin was identical to that of authentic angiogenin purfied from human plasma when estimated by SDS-PAGE and immunoblotting. showing that the natural leader sequence was recognized and processed by the secretion machinery of E. coli. The angiogenin concentration in the culture medium reached a maximum within 2 h when expressed at $37^{\circ}C$ with 0.02~2 mM IPTG. In contrast, the expression level increased gradually over time up to 11 h at $23^{\circ}C$ with 0.002~2 mM IPTG and at $37^{\circ}C$ with 0.002 mM IPTG.

• 한국결정학회지
• /
• 제4권2호
• /
• pp.92-99
• /
• 1993

Diethylzinc를 사용하여 PECVD장치로 ZnO 박막을 증 착하여 미세구조를 분석하였다. 기판 온도 100℃에서부터 이미 미세 결정 입자로 구성된 ZnO 박막의 증착이 가능했으며, 200℃이상에서는 C 축 배향성이 뛰어난 ZnO 박막이 유리 기판위에 증착되었다. c-면 사파이어 기판위에 증착된 ZnO 박막을 TEM으로 분석한 결과 기판 온도 350℃에서 EPITAXIAL (002) ZnO 박막이 성장됐으며, 입계에서는 Moire패턴에 의한 dislocation이 관찰되었다.