• Journal of Biomedical Engineering Research
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• v.7 no.1
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• pp.75-79
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• 1986

In this paper, a multigate pulsed doppler system with parallel signal processing which enables the transcutaneous assesment of the blood-flow velocities of five adjacent sample volumes is developed. The outputs of the system are audio signals, velocity curves and velocity profiles of 5 adjacent sample volumes. We have applied to the major superficial arteries and obtained the detailed information about the time dependent blood-flow behavior.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.746-749
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• 2003

Alignment of 2D-gel images of biological samples can visualize the difference of expression profiles and also inform us candidates of protein spots to be further analyzed. However, comparison of two proteome images between case and control does not always successfully identify differentially expressed proteins due to sample-to-sample variation. Because of poor reproducibility of 2D-gel electrophoresis, sample-by-sample variations and inconsistent electrophoresis conditions, multiple number of 2D-gel image must be processed to align each other to visualize the difference of expression profiles and to deduce the protein spots differentially expressed with reliability. Alignment of multiple 2D-Gel images and their clustering were carried out by applying various algorithms and statistical methods. In order to align multiple images, multiresolution-multilevel algorithm was found out to be suitable for fast alignment and for distorted images. Clustering of 12 different images implementing a k-means algorithm gives a phylogenetic tree of distance map of the proteomes. Microsoft Visual C++ was used to implement the algorithms in this work.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.360-363
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• 1994

Column--swtiching technique with a reversed-phase high performance liquid chromatographic method has been developed for the routine analysis of radioiodinated insulin and its degadation products in biological fluids. The diluted biological samples were loaded onto a precolumn packed with LiChrosorb RP-8 $(25-40{\;}{\mu}m)$ using 0.1% trifuoroacetic acid (TFA) in water as a washing solvent. After valve switching, the concentrated insulins were eluted in the back-flush mode and separated by a W-Porex $C_{18}$ column with a gradient of 0.1% TFA in water and 0.1% TFA in acetonitrile as the mobile phase. The method showed good precision, accuracy and speed with the detection limit of 20 pg/ml. Total analysis time per sample was about 40 min and the coefficients of variation were less than 8, 2%.

• Korean Journal of Ecology and Environment
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• v.43 no.4
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• pp.477-491
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• 2010

Benthic macroinvertebrates were collected two times from 116 sites at the $1^{st}{\sim}4^{th}$ order streams in forest areas in Gyungsang province in late spring and late summer. The sample sites belonged to slightly and moderately polluted states. When communities were classified by the Self-Organizing Map (SOM), the gradient was observed according to degree of pollution. Within clusters of slightly polluted sites, however, seasonality was further observed. Scrapers, gatherer-collectors, and filterer-collectors were abundantly observed in late spring while shredders appeared more in late summer. The number of predator species increased in late summer. Behavior types were mostly clingers in two seasons. Community compositions at the moderately polluted sites were not much differentiated in different seasons. Gatherer-collectors and burrowers were dominantly collected in both seasons.

• Applied Microscopy
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• v.42 no.1
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• pp.49-52
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• 2012

For TEM study of biological samples or polymers that are contained in organic structure, it is often required that the sample is prepared by using ultramicrotome and stained with proper agents to increase the contrast of organic structure. In this study, we investigated an efficient TEM sample preparation method for ductile heterogeneity material by using ultramicrotomy. Cryo-ultramicrotomy is a suitable method that is capable of rendering sample hardness for various ductile materials. However, it has several factors to consider, such as experimental cost, working time and finding the optimal staining conditions. To satisfy these considerations, we prepared TEM sample by using ultramicrotome without cryofunction, and secured the sample hardness by applying the staining process prior to ultrathin sectioning. The cross-linked polyethylene structure in the sample was stained with the 2% $RuO_4$ solution in a sealed test tube for 24 hours at $4^{\circ}C$. After the sample staining, ultrathin sections of sample were prepared using ultramicrotome. As a result, it was revealed that the difficulties associated with staining of ultrathin sections prepared by low-temperature conditions were improved. In addition, appropriate staining depth of sample could be selected for sectioning process. The quality of TEM sample obtained by using this method was better than that of cryo-ultramicroscopy. Finally, it is expected that our method could be effectively applied in TEM sample preparation for a variety of nano-bio convergence materials.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.295-305
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• 2002

Benthic macro- invertebrates were collected in a 200 m reach located in the $3^{rd}$ order Yangjae Stream, a tributary of the Han River, Seoul, from April 1996 to March 1998. Although species richness was relatively low due to organic pollution, community abundance patterns appeared to be different depending upon location of the sampling sites. At the sample sites in the straight zone with high water velocity and large substrates, species richness was high and species relatively less-tolerant to organic pollution was additionally present. At the sample sites in the pool zone with lower velocity and high sedimentation, species richness was low and a few tolerant species to organic pollution were abundantly collected. The principle component analysis indicated that some sample sites in the straight zone appeared to be related to water velocity and shear velocity, and associated with diverse taxa less tolerant to organic pollution. Additionally the sample site transplanted with large substrates was associated wit]h hydraulic characters such as substrate diversity and roughness, and was related to species indicating partial recovery of water. The sample sites located at the pool zone tended to be associated with organic matter that had sedimented on to the substrates and the taxa tolerant to organic pollution, including Oligochaeta and Chironomus.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1071-1077
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• 2019

Natural gamma-decalactone (GDL) produced by biotransformation is an essential food additive with a peach-like aroma. However, the difficulty of effectively controlling the concentration of the substrate ricinoleic acid (RA) in water limits the biotransformation productivity, which is a bottleneck for industrialization. In this study, expanded vermiculite (E-V) was utilized as a carrier of RA to increase its distribution in the medium. E-V and three commonly used organic compounds were compared with respect to their effects on the biotransformation process, and the mechanism was revealed. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis indicated that RA was physically adsorbed onto the surface of and inside E-V instead of undergoing a chemical reaction, which increased the opportunity for interactions between microorganisms and the substrate. The highest concentration of GDL obtained in the medium with E-V was 6.2 g/l, which was 50% higher than that in the reference sample. In addition, the presence of E-V had no negative effect on the viability of the microorganisms. This study provides a new method for producing natural GDL through biotransformation on an industrial scale.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.28-33
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• 2004

This study was performed to examine in vitro biological activities such as antioxidative, nitrite scavenging effect, tyrosinase inhibitory effect and antithrombotic activity of a Korean traditional prescription, Nogyong-daebotang, composed of oriental medical herbs and antler, nourishing the blood, helthiness, strengthening of vital power and promotion of growth. The concentration of total phenolic compounds of the prescription sample was 151.3$\pm$2.6 mg％. The electron donating abilities (EDA) by reduction of 2.2'-diphenyl-1-picrylhydrazyl (DPPH) was 80.9%, inhibition rate of lipid peroxidation in thiocyanate method used linoleic acid was 88.1%. Nitrite scavenging effects of the sample were more than 70% at acidic pH, but it was pH dependent, showing the highest at pH 1.2 and the lowest at pH 6.0. Inhibition rate against tyrosinase of the sample was above 80%. Platelet aggregation induced by ADP (adenosine-5'-diphosphate) was inhibited up to 30% and the inhibitory effect was dependent on concentration of the sample.

• Korean Journal of Environmental Biology
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• v.26 no.3
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• pp.183-191
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• 2008

The effect of silver ion solution on the growth of Microcystis aeruginosa UTEX 2388 (cyanobacterium) and Chlorella sp. KCTC AG20136 (green alga) was investigated using separated and mixed culture in filtered natural water and BG11 medium. In separated culture, M. aeruginosa UTEX 2388 and Chlorella sp. KCTC AG20136 were found to be sensitive to 0.01 and 0.1 mg L$^{-1}$ of silver ion, respectively. Also, the silver ion concentrations for the growth inhibition of M. aeruginosa UTEX 2388 and Chlorella sp. KCTC AG20136 in the mixed culture were same in separated culture. Cyanobacteria were more sensitive to the silver ion solution than green algae. In bloom sample, the minimal inhibition concentration of silver ion solution for the low Chl-${\alpha}$ sample (110$\sim$190 ${\mu}g$ L$^{-1}$) and high Chl-${\alpha}$ sample (1,500$\sim$1,900 ${\mu}g$ L$^{-1}$) was about 0.1 and 3.0 mg L$^{-1}$, respectively. The silver ion concentration for the inhibition of algal bloom sample was affected by the algal biomass. In order to use silver ion solution for the control of algal bloom, the silver ion concentration must be determined in consideration of a minimal effect on the environment.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.265-271
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• 1992

Derivatives (microcrystalline chitin, carboxymethylchitin, acetylchitin, N-acetylchitosan, ethylchitosan and chitosansulfate) of chitin and chitosan were synthesized, and the physicochemical properties of the derivatives were compared with those of chitin and chitosan. Carboxymethylchitin was soluble in water or acetic acid, whereas chitosan and ethylchitosan were soluble in acetic acid alone. The water binding capacity of N-acetylchitosan was two fold higher than that of chitin. Lipid binding capacity of carboxymethylchitin was the highest, holding 1800%, and that of chitin was the lowest, holding 511% among the derivatives. Carboxymethylchitin among the derivatives showed the highest emulsifying capacity, however chitin and chitosan didn't produce emulsions. Dye binding capacity of acetylchitin was the highest, holding 0.93 mg dye/g sample (Blue R-250) and 0.96 mg dye/g sample (Red No. 2). It was concluded that carboxymethylchitin is a good emulsifier and N-acetylchitosan, chitosansulfate and chitosan are suitable for use as dye absorbents.