• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 G
• /
• pp.2541-2543
• /
• 1998

This paper describes the fabrication process to fabricate metallic structure of high aspect ratio using LlGA-like process. SU-8 is used as an electroplating mold. SU-8 is an epoxy-based photoresist, designed for ultrathick PR structure with single layer coating [1,2]. We can get more than $100{\mu}m$ thick layer by single coating with conventional spin coater, and applying multiple coating can make thicker layers. In the experiments, we used different kinds of SU-8, having different viscosity. To optimize the conditions for mold fabrication process, experiments are performed varying spinning time and speed, soft-bake, develop and PEB (Post Expose Bake) condition. With the optimized condition, minimum line and space of $3{\mu}m$ pattern with a thickness of $40{\mu}m$ and $4{\mu}m$ pattern with a thickness of $130{\mu}m$ were obtained. Using the patterned PR as a plating mold, metallic structure was fabricated by electroplating. We have fabricated a electroplated nickel comb actuator using SU-8 as plating mold. The thickness of PR mold is $45{\mu}m$ and that of plated nickel is$40{\mu}m$. Minimum line of the mold is $5{\mu}m$. Patterned metallic layer or polymer layer, which has selectivity with the structural plated metallic layer, can be used as sacrificial layer for fabrication of free-standing structure.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
• /
• pp.88-91
• /
• 2000

An MMIC oscillator operating at the 24.55 GHz has been designed using 0.2 ${\mu}{\textrm}{m}$AlGaAs/InGaAs/GaAs Pseudomorphic HEMT technology. The active device used in the oscillator design has a 0.2 ${\mu}{\textrm}{m}$ gate length PHEMT with 4$\times$80 ${\mu}{\textrm}{m}$ gate width. We obtained 4.08 dB of S$_{21}$ gain and 317 mS/mm of transconductance, and extrapolated unit current gain cut-off frequency (f$_{T}$) and maximum oscillation frequency (fmax) were 62 GHz and 120 GHz, respectively. The circuit are based on a series feedback and negative resistance topology. Microstrip line open stub is used to terminating. The oscillator circuits has designed for delivering maximum power to load and conjugated matching. The simulated small signal negative resistance was 50 Ω. We obtained 1.002 of loop gain and 0.0005$^{\circ}$angle from the simulation by HP libra 6.1. The layout for oscillator is 1.2$\times$1.8 $\textrm{mm}^2$.>.

• 대한수의학회지
• /
• 제24권2호
• /
• pp.163-168
• /
• 1984

The in vitro activity of penicillins(penicillin G, ampicillin, carbenicillin, methicillin and cloxacillin) and gentamicin to Staphylococcus aureus and coagulase-negative staphylococci isolated from bovine mastitic milk samples was determined. The growth of all isolates of staphylococci tested was inhibited by cloxacillin and methicillin at a concentration of $0.78{\mu}g/ml$ and by gentamicin at a minimum inhibitory concentration (MIC) of $1.56{\mu}g/ml$. Of the 140 strains of Staphylococcus aureus isolated 99(70.7%) gave positive reactions for penicillinase on the starch-iodine test. Of 121 isolates of coagulase-negative staphylococci, 58(47.9%) showed penicillinase production, but all the Staph. xylosus lacked the ability to produce penicillinase. MIC of penicillin G of the penicillinase-positive strains was $0.2{\mu}g/ml$ or more. The combination of cloxacillin with gentamicin showed a synergistic effect by inhibiting regrowth of the tested organism.

• East Asian mathematical journal
• /
• 제4권
• /
• pp.57-73
• /
• 1988

The subclasses S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) ($0\leqq\alpha<1,\;0<\beta\leqq1$ and $0\leqq\mu\leqq1$) of T the class of analytic and univalent functions of the form $$f(z)=z-\sum\limit^{\infty}_{n=2}\mid a_n\mid z^n$$ have been considered. Sharp results concerning coefficients, distortion of functions belonging to S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) are determined along with a representation formula for the functions in S*($\alpha,\beta,\mu$). Furthermore, it is shown that the classes S*($\alpha,\beta,\mu$) and C*($\alpha,\beta,\mu$) are closed under arithmetic mean and convex linear combinations. Also in this paper, we find extreme points and support points for these classes.

• 미생물학회지
• /
• 제34권1_2호
• /
• pp.31-36
• /
• 1998

지네 Scolopendra subspinipes multilans L. Koch로부터 정제한 Centipedin의 gram-negative, gram-positive bacteria 및 fungi에 대한 광범위 항균 spectrum을 조사하였으며 액체배지를 사용하여 각 균주에 대한 minimal inhibitory concentrations(MICs)값을 측정하였다. 인체의 기관중 주로 폐에 감염되는 gram-negative bacteria인 Klebsiella pneumoniae ATCC 8308 균주에 대한 MIC값이 $2{\mu}g/ml$로서 가장 강한 항균력을 나타내었고 화농균인 Proteus vulgaris NRRL B-123 균주에 대해서도 MIC값이 $16{\mu}g/ml$로 비교적 높은 항균력을 나타내었으며 항균제로서의 작용 mechanism을 시험한 결과 prokaryotic RNA transcription을 억제함을 알 수 있었다. Human blood leukemia(HL-60)와 mouse B lymphocyte myeloma cell 등의 동물세포에 대한 Centipedin의 cytotoxicity는 없는 것으로 확인되었다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제13권1호
• /
• pp.39-47
• /
• 2009

Gaegurin 4(GGN 4), an antimicrobial peptide isolated from a Korean frog, is five times more potent against Gram-positive than Gram-negative bacteria, but has little hemolytic activity. To understand the mechanism of such cell selectivity, we examined GGN4-induced $K^+$ efflux from target cells, and membrane conductances in planar lipid bilayers. The $K^+$ efflux from Gram-positive M. luteus(2.5 ${\mu}g/ml$) was faster and larger than that from Gram-negative E. coli(75 ${\mu}g/ml$), while that from RBC was negligible even at higher concentration(100 ${\mu}g/ml$). GGN4 induced larger conductances in the planar bilayers which were formed with lipids extracted from Gram-positive B. subtilis than in those from E. coli(p<0.01), however, the effects of GGN4 were not selective in the bilayers formed with lipids from E. coli and red blood cells. Addition of an acidic phospholipid, phosphatidylserine to planar bilayers increased the GGN4-induced membrane conductance(p<0.05), but addition of phosphatidylcholine or cholesterol reduced it(p<0.05). Transmission electron microscopy revealed that GGN4 induced pore-like damages in M. luteus and dis-layering damages on the outer wall of E. coli. Taken together, the present results indicate that the selectivity of GGN4 toward Gram-positive over Gram-negative bacteria is due to negative surface charges, and interaction of GGN4 with outer walls. The selectivity toward bacteria over RBC is due to the presence of phosphatidylcholine and cholesterol, and the trans-bilayer lipid asymmetry in RBC. The results suggest that design of selective antimicrobial peptides should be based on the composition and topology of membrane lipids in the target cells.

• 대한전자공학회논문지TC
• /
• 제45권8호
• /
• pp.60-68
• /
• 2008

구형 도파관 기법을 이용하여 다양한 모양을 가진 주기적인 metamaterial (MTM) 셀의 복소 유전율과 투자율을 시뮬레이션으로 추출하였다. 이 도파관은 PEC 벽과 PMC 벽으로 구성된 가상적인 것이고, 고려된 MTM 셀의 모양은 thin wire (TW), single split-ring resonator (SSRR), double SRR (DSRR), modified SRR, 그리고 TW와 DSRR이 결합된 구조이다. TW는 음의 유전율/양의 투자율, SRR은 양의 유전율/음의 투자율, 그리고 TW와 DSRR을 합친 구조는 유전율과 투자율이 동시에 음이 되는 영역이 나타남을 확인하였다. 각 셀의 파라미터에 따른 유전율과 투자율의 변화를 살펴보았다. 추가적인 연구로서 상기 도파관 기법의 단점을 보완하는 시 영역 신호를 이용한 추출 방법을 소개했다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권4호
• /
• pp.457-462
• /
• 2014

This letter proposes a low-jitter DLL-based clock generator with two negative feedback loops. The main negative feedback loops suppress the jitter of DLL. The additional negative feedback loops suppress the delay-time variance of each delay stages. Both two negative feedback loops in a DLL results in suppressing the jitter of clock signal further. Measurement results of the DLL-based clock generator with two negative feedback loops fabricated in a one-poly six-metal $0.18{\mu}m$ CMOS process show 5.127-ps rms jitter and 47.6-ps peak-to-peak jitter at 1 GHz.

• 한국균학회지
• /
• 제23권2호통권73호
• /
• pp.176-189
• /
• 1995

98종의 한국산버섯의 그람음성균에 대한 항균활성을 검색한 결과 20종의 버섯의 80% 에탄올(E) 및 증류수(H) 추출물이 Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens, Shiegella sonnei, Shiegella dysenteiae, Salmonella typhi, Salmonella typhimurium 및 Pseudomonas aeruginosa에 대하여 항균력을 나타내며, 특히 R. sinuatus, S. luteus, B. umbriniporus, 그리고 A. tabescens의 E 추출물은 다른 버섯에 비하여 여러 종류의 그람음성균에 대하여 다양한 항균활성을 보였다. Abortiporus biennis, Phellinus gilvus, 및 Polyporus dispansus의 E 추출물은 S. typhi에 대하여 강력한 항균력을 나타내었으며 이들의 MIC는 $10\;{\mu}g/ml$이었다. 25종 버섯의 곰팡이균에 대한 항균활성을 검색한 결과 Armillariella tabescens의 E 추출물이 Trichopyton mentagrophytes에 대하여 항균력을 가지며 이의 MIC는 $300\;{\mu}g/ml$이었다.

• 대한수의학회지
• /
• 제39권4호
• /
• pp.765-771
• /
• 1999

Unlike most Escherichia coli strains, E coli O157 : H7 didn't ferment sorbitol within 24h of incubation and showed a negative reaction for $\beta$-glucuronidase. We developed a new medium for the rapid isolation of E coli O157 : H7 using sorbitol MacConkey agar with cefixime, potassium tellurite and 4-methylumbelliferyl-${\beta}$-D-glucuronide (MUG) as a primary plating medium. The addition of $20{\mu}g/ml$ of vancomycin in enrichment broth for E coli O157 : H7 inhibited lots of Gram positive bacteria. Three strains (10.3%) of 29 non-O157 E coli strains and 3 strains (8.3%) of 36 Salmonella spp were inhibited at the $0.05{\mu}g/ml$ of cefixime and 23 strains (79.3%) of 29 non-O157 E coli strains and 12 strains (33.3%) of 36 Salmonella spp were inhibited at the $2.0{\mu}g/ml$ of potassium tellurite. But none of the E coli O157 : H7 was affected at these concentration. The addition of MUG at $100{\mu}g/ml$ level to sorbitol MacConkey agar with cefixime and potassium tellurite (CTM-SMAC) aided in the rapid isolation of E coli O157 : H7 from samples by checking sorbitol-negative and $\beta$-glucuronidase negative phenotypes simultaneously. In conclusion, inoculation of a positive in the O157 screening test from enrichment broth on CTM-SMAC appeared to be a rapid, cost-effective and sensitive method for the isolation of E coli O157 : H7.