• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.154.2-154.2
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• 2007

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.595-597
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• 1998

This paper deals with an algebraic compensator design for dynamic systems using a novel BPF transformation method. To obtain an algebraic compensator for the system, block pulse function's differential operation is used. Compare to unalgebraic compensator, proposed algebraic compensator is less sensitive to the measurement noise.

• Journal of the Korean Ceramic Society
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• v.43 no.4 s.287
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• pp.203-206
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• 2006

Polyacrylonitrile (PAN) nanofibers, which are pH-sensitive and exhibit soft actuation as a linear actuator and artificial muscles, were prepared by electrospinning to investigate the effect of viscosity on the morphology of PAN fibers. Experimental results revealed that higher viscosity is critical for the formation of unbeaded nanofibers because surface tension is almost constant throughout the experiment. Uniform, smooth, and continuous fibers with diameters of about 700 nm were achieved for the 10 wt% PAN fibers at a flow rate of 0.5 mL/h and an electric field of 0.875 kV/cm.

• Mycobiology
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• v.29 no.3
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• pp.142-144
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• 2001

The tetrahydropahnatine alkaloid was assayed against spore germination of some saprophytic and pathogenic fungi e.g., Alternaria solani, A. brassicicola, A. brassicae, A. alternata, Erysiphe pisi, Curvularia lunata, C. pallescens, C. maculans, Curvularia species, Colletotrichum species, C. musae, Helminthosporium echinoclova, H. pennisetti, H. spiciferum, and Heterosporium sp. It inhibite spore germination of all the fungi tested. Colletotrichum spp. Curvularia lunata, Helminthosporium spiciferum and Heterosporium sp. were most sensitive as complete inhibition of spore germination was observed at very low concentration(200 ppm).

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1560-1564
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• 2005

The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from $2.5\;{\times}\;10^{-8}\;to\;1\;{\times}\;10^{-6}$ mol/L, and the detection limit was found to be $7.5\;{\times}\;10^{-9}$ mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.

• Mycobiology
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• v.35 no.2
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• pp.62-64
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• 2007

An allosecurinine alkaloid was assayed against spore germination of some saprophytic and pathogenic fungi e.g., Alternaria alternata, A. solani, A. brassicicola, A. brassicae, Curvularia lunata, C. pallescens, C. maculans, Curvularia species, Colletotrichum species, C. musae, C. gloeosporioides, Erysiphe pisi, Fusarium udum, Helminthosporium echinoclova, H. pennisetti, H. spiciferum, and Heterosporium sp. It inhibited mild spore germination of all the fungi tested. Curvularia lunata, Curvularia sp., Collectotrichum sp., C. musae and Heterosporium sp. were most sensitive as complete inhibition of spore germination was observed at very low concentrations.

• Journal of Microbiology
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• v.39 no.2
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• pp.146-148
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• 2001

Lactobacillus crispatus ATCC 33820 and L. gasseri ATCC 33323 were grown in MRS broth (pH 6.5) at 37$^{\circ}C$ for 24 h and the antibacterial activities of cell free culture supernatants were determined by the agar well diffusion method. The culture supernatants were inhibitory to Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Pediococcus acidilacticii, and Lactobacillus helveticus. The supernatants did not show any lysozyme activity. Addition of catalase did not affect the antibacterial activities of the supernatants. The antibacterial substances were heat stable (100$^{\circ}C$ for 60 min) and sensitive to proteases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.1
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• pp.54-63
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• 2018

We investigated the effect of $CO_2$ exposure on the reproductive process of chameleon goby Tridentiger trigonocephalus. Rearing aquaria were exposed for 90 days to $CO_2$ gas through diffuser connected with pH controller maintaining at pH 7.2 ($156.31{\pm}7.90ppm$) in low treatment, and at pH 6.5 ($274.17{\pm}6.51ppm$) in high treatment. $CO_2$ treatment had no significant effects on survival rates although the value was decreased compared to the controls. In female fish, $CO_2$ treatment had no significant effects on gonadosomatic index (GSI), hepatosomatic index (HSI) and condition factor (CF). However, high $CO_2$ treatment decreased HSI and CF in males significantly compared to the controls (P<0.05). The spawning occurrence was 6 times in the low level $CO_2$ treatment, and 4 times in the high level $CO_2$ treatment although only once in the controls. For the histological observations, there was no significant difference in $CO_2$ treatments. However, in male fish, $CO_2$ treatment delayed the formation of sperm from spermatid compared to controls. These results suggest $CO_2$ may disrupt reproductive process by delaying gametogenesis in chameleon goby and it was more sensitive in males.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.50-54
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• 2005

Antimicrobial activities of ethanol extracts of marta rosemary (Rosemarinus officinalis L.) against Bacillus subtilis and Salmonella typhimurium were investigated under conditions similar to processing of general food materials to develop natural food preservatives. The strongest antimicrobial activities were shown against the tested organisms at pH 7. In B. subtilis, the herbal extract extended the lag phase at low concentrations, and reduced the specific growth rate during logarithmic phase at high concentrations. In S. typhimurium the herbal extract reduced the specific growth rate even at lower concentrations. These trends were obtained at low pHs of culture solution. Antimicrobial substances of herbs were efficiently extracted with low polar solvents. The thermal stability of antimicrobial substances decreased with heating time at $100^{\circ}C$. S. typhimurium was more sensitive to herbal extracts at $100\;and\;121^{\circ}C$ than B. subtilis.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1938-1940
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• 2003

본 연구는 요소 센서 제작을 위한 과정으로서, 전기화학적 방법을 이용한 다공질 실리콘 구조 형성과, PDV(Physical Vapor Deposition) 법에 의한 백금 박막 코팅 및 전기화학적 전도성 고분자 코팅과 urease 고정화 단계를 고찰하고 감도 특성을 제시 하였다. 전극 기질로서 B을 도우핑한 p-type 실리콘웨이퍼를 사용하였고, HF:$C_2H_5OH:H_2O$=1:2:1의 부피비를 갖는 에칭 용액에서 5분간 -7 $mA/cm^2$의 일정 전류를 가하여 폭 2 ${\mu}m$, 깊이 10 ${\mu}m$의 다공질 실리콘(PS) 충을 형성하였다. 그 위에 200 ${\AA}$의 Ti 층을 underlayer로서 증착하고, 2000 ${\AA}$의 Pt를 중착하여 PS/Pt 박막 전극을 제작하고, 전도성 고분자로서 polypyrrole (PPy), 또는 poly(3-mehylthiophene) (P3MT)을 전기화학적으로 코팅한 후, urease(EC 3.5.1.5, type III, Jack Bean, Sigma)를 고정화 하였다. 고정화 시 전해질 수용액의 pH는 7.4로 하여 urease표면이 음전하를 갖도록 하고, 전극에 0.6 V (vs. SCE(Saturated Calomel Electrode))의 일정 전압을 가함으로써 urease가 전도성 고분자 표면에 전기적으로 흡착되도록 하였다. 이상의 방법으로 제작한 요소 센서의 감도는 PPy와 P3MT를 전자 전달 매질로 사용한 경우, 각각 8.44 ${\mu}A/mM{\cdot}cm^2$와 1.55 ${\mu}A/mM{\cdot}cm^2$의 감도를 보였다.