• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.113-117
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• 1997

In this paper we detected the thrombosis formation by spectral analysis and neural network. Using microphone and amplifier, we measured the sound from the mechanical valve which is attached to the pneumatic ventricular assist device. The sound was sampled by A/D converter and the periodogram is the main algorithm or obtaining spectrum. We made the valvular thrombosis models using pellethane and silicon and they are thrombosis model on the disk, around the sewing ring and fibrous tissue growth across the orifice of valve. The spectrum of normal and 5 kinds of thrombotic valve were obtained and primary and secondary peak appeared in each spectrum waveform. So to distinguish the secondary peak of normal and thrombotic valve quantatively, 3 layer back propagation neural network.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.215-220
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• 1995

In this paper, we study myoelectric signal variation through kyungrak needle stimulation. The signal are detected from two kyunrak route of arm; before and after stimulation of a needle, and before and after needle rotation. The detected signals are analyzed at frequency domain to search a characteristic parameters. At the rotation method, spectrum denity of the signals varies large but spectrum is not detected before and after rotation. We can not see any relation bet ween spectrum variation and rotational direction. As the results, when the same stimulation method is used at two different kyungrak route respectively, it is found that the variation of the myoelectric signal is not same.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.162.1-162.1
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• 2015

The use of plasma has increased in bio-application field in recent years. Particularly, water treated by arc discharge or atmospheric pressure plasma has been actively utilized in bio-industry. In this study, we have developed a plasma activated water generating system. For this system, two kinds of plasma sources; dielectric barrier discharge (DBD) plasma and arc discharge plasma have been used. The discharge energy was calculated using the breakdown voltage and current, and the emission spectrum was measured to investigate the generated reactive species. We also analyzed the amount of reactive oxygen and nitrogen species in water using the chemical methods and nitric oxide sensor. Finally, the influence of plasma generated reactive species on the germination and growth of spinach (Spinacia oleracea) was investigated. Spinach is a green leafy vegetable that contains a large amount of various physiologically active organic compounds. However, it is characterized with a low seed germination rate.

• Applied Biological Chemistry
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• 제41권4호
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• pp.209-212
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• 1998

Methylan, a polysaccharide produced from Methylobacterium organophilum, was chemically modified by adding diethylaminoethyl (DEAE) group to the backbone of methylan. The structure of DEAE-methylan was determined by measuring its nitrogen content obtained from an elemental analysis. From the analysis of mass spectrum, the DEAE group in DEAE-methylan was also confirmed by determining diethylaminoethene as a separate form of DEAE. Mercury adsorption of DEAE-methylan was higher than that of native methylan. This fact was valid for a variety of pH, reaction times, metal concentrations, and polysaccharide concentrations. In particular, native methylan and DEAE-methylan adsorbed 16% (w/w) and 18% (w/w) for mercury after 30 min at pH 7, respectively. The increase in mercury adsorption of DEAE-methylan may be resulted from mercury adsorption by the lone pair electron of nitrogen atom in DEAE group.

• Macromolecular Research
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• 제15권4호
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• pp.330-336
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• 2007

Luminescent CdSe/ZnS QDs, with emission in the red region of the spectrum, were synthesized and encapsulated in poly(ethylene glycol)-poly(D,L-lactide) diblock copolymer micelles, to prepare water-soluble, bio-compatible QD micelles. PEG-PLA diblock copolymers were synthesized by ring opening polymerization of D,L-lactide, in the presence of methoxy PEG as a macro initiator. QDs were encapsulated with PEG-PLA polymers using a solid dispersion method in chloroform. The resultant polymer micelles, with encapsulated QDs, were characterized using various analytical techniques, such as UV- Vis measurement, light scattering, fluorescence spectroscopy, transmission electron microscopy (TEM) and atomic forced microscopy (AFM). The polymer micelles, with encapsulated QDs, were spherical and showed diameters in the range of 20-150 nm. The encapsulated QDs were highly luminescent, and have high potential for applications in biomedical imaging and detection.

• Journal of Microbiology
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• 제43권2호
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• pp.172-178
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• 2005

To determine the prevalence and genotypes of $\beta$-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced $\beta$-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five ($167\%$) of thirty clones produced an extended-spectrum $\beta$-lactamase. 837- and 259-bp fragments specific to bla$_{TEM}$ genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM­1 was the most prevalent $\beta$-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type $\beta$-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type $\beta$-lactamases of the pre-antibiotic era indicates that TEM-type $\beta$-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.

• Journal of Microbiology and Biotechnology
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• 제22권6호
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• pp.872-881
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• 2012

The inhibitory effect of the Klebsiella pneumoniae ATCC 13883 strain caused by the hexane extract of Halimeda discoidea (Nor Afifah et al., 2010) was further evaluated by means of the microscopy view and its growth curves. The morphological changes of the K. pneumoniae ATCC 13883 cells were observed under the scanning electron microscope (SEM) and transmission electron microscope (TEM) after they were treated at minimum inhibitory concentration (MIC; 0.50 mg/ml) (Nor Afifah et al., 2010) for 12, 24, and 36 h. The results showed the severity of the morphological deteriorations experienced by the treated cells. The killing curve assay was performed for 48 h at three different extract concentrations (1/2 MIC, MIC, and 2 MIC). An increase in the extract concentration of up to 2 MIC value did significantly reduce the number of cells by approximately 1.9 $log_{10}$, as compared with the control. Identification of the potential compounds of the extract responsible for the antibacterial activity was carried out through the gas chromatography-mass spectrum (GC-MS) analysis of the active subfraction, and the compound E-15-heptadecenal was identified and suggested as the most potential antibacterial compound of this extract. The subsequent cellular degenerations showed by the data might well explain the inhibitory mechanisms of the suggested antibacterial compound. All of these inhibitory effects have further proven the presence of an antibacterial compound within H. discoidea that can inhibit the growth of K. pneumoniae ATCC 13883.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.240-242
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• 1996

In this paper, we proposed a method of a hearing aid suitable for the sensorineural hearing impaired. Generally as the sensorineural hearing impaired have narrow audible ranges between threshold and discomfortable level, the speech spectrum may easily go beyond their audible range. Therefore speech spectrum must be optimally amplified and compressed into the impaired's audible range. The level and frequency of input speech signal are varied continuously. So we have to make compensation input signal for frequency-gain loss of the impaired, specially in the frequency band which includes much information. The input sigaal is divided into short time block and spectrum within the block is calculated. The frequency-gain characteristic is determined using the calculated spectrum. The number of frequency band and the target gain which will be added input signal are estimated. The input signal within the block is processed by a single digital filter with the calculated frequency-gain characteristics. From the results of monosyllabic speech tests to evaluate the performance of the proposed algorithm, the scores of test were improved.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 추계학술대회
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• pp.233-234
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• 1995

• 대한의용생체공학회:의공학회지
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• 제6권1호
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• pp.47-54
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• 1985

In this paper, clutter in ultrasound pulsed Doppler system is analyzed mathematically. And stationary canceler which reduce the clutter is designed. The operating characteristics of the stationary canceler is investigated in body (in vivo) by audio signal and spectrum analyzer.