• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.168-171
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• 2000

The thermal stability and catalytic activity of phospholipase A$_1$ from Serratia sp. MK1 were improved by an evolutionary molecular engineering. Two thermostable mutants were isolated after sequential rounds of error-prone PCR to introduce random mutations and filter-based screening of the resultant mutant library, and identified as having six (mutant TA3) and seven (mutant TA13) amino acid substitutions, respectively. Different types of the substitutions were found in two mutants, resulting in the increase of nonploar residues (mutant TA3) or changes between side chains within polar or charged residues (mutant TA13). The wild-type and mutant enzymes were purified, and the effect of temperature on their stability and catalytic activity was investigated. The T$\sub$m/ values of TA3 and TA13 were increased by 7 and 11$^{\circ}C$, respectively. Thus, evolutionary molecular engineering was found to be an effective and efficient approach to increasing thermostability without compromising enzyme activity.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.362-365
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• 2000

A rapid immunochromatographic assay kit using whole blood to screen hepatitis B surface antigen was developed and evaluated by using sera from 240 patients. The reference diagnosis was based on the results obtained with GENEDIA Anti-HBs Rapid kit which is very similar to the above kit except for the use of serum. The test demonstrated a good correlation with the reference immunochromatographic assay kit, that is, the sensitivity and the specificity of the kit was 100%, respectively. The rapid test kit using whole blood should be more convenient and useful for the diagnosis of hepatitis B virus because the kit does not need machines and time to prepare serum. In addition, this kit is safe from inadvertent infection during sample treatment because the blood is sterilized with hydrogen peroxide, eliminates the procedure required to prepare serum and reduces the possibility of exposure to infectious agents.

• Mycobiology
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• v.39 no.3
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• pp.226-229
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• 2011

An unrecorded Antrodia species was collected in South Korea and based on morphological characteristics, the species was identified as Antrodia sitchensis. To confirm its affinity within the polypores, the phylogenetic relationships of A. sitchensis and allied species were established using large subunit rDNA sequences.

• Macromolecular Research
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• v.17 no.7
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• pp.506-515
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• 2009

We synthesized a series of polystyrene derivatives containing various side chain terminal moieties, such as phenoxymethyl, 4-methoxyphenoxymethyl, 4-fluorophenoxymethyl, 4-methylphenoxymethyl, and 4-trifluoromethoxyphenoxymethyl groups, using polymer analogous reactions, in order to investigate the effect of the side group on their liquid crystal (LC) alignment behaviors. The polymers containing 4-fluorophenoxymethyl, 4-methylphenoxymethyl, or 4-trifluoromethoxyphenoxymethyl side groups had lower surface energy values and the LC cells fabricated using the unrubbed films of these polymers showed homeotropic LC alignment behavior. The LC cells fabricated using the rubbed films of the polymers containing phenoxymethyl or 4-fluorophenoxymethyl groups showed homogeneous planar LC alignment behavior in which the LCs were aligned perpendicular to the rubbing direction. This homogeneous planar and perpendicular alignment behavior was ascribed to the favorable anisotropic interactions between the LC molecules and the side groups preferentially oriented perpendicular to the rubbing direction.

• Macromolecular Research
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• v.17 no.2
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• pp.79-83
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• 2009

The oral delivery of heparin is the preferred therapy in the treatment of patients with a high risk of deep vein thrombosis and pulmonary embolism. New conjugates of heparin and sodium deoxycholate were synthesized in order to enhance the heparin absorption in the GI tract. After oral administration of DOC-heparin, the concentration in anti-FXa assay was increased with increasing amount of coupled DOC. The maximum concentration of DOC-heparin VIII conjugate was $3.3{\pm}0.5\;IU/mL$ at an oral dose of 10 mg/kg, which was 3-fold higher than the baseline level. Finally, DOC coupled to heparin greatly enhanced the absorption of heparin in the GI tract, and this enhancing effect was not induced by changing the tissue structure of the GI wall.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.37-39
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• 1996

For the laryngeal function assessment, we developed a measurement system of speech sound and air flow rate. The speech sound was transduced with a standard omnidirectional condenser microphone and orally emitted air flow was measured with pneumotachometer using differential pressure transducer.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.33-36
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• 1996

In this paper, we present the Computerized Polysomnographic System, which we developed for aiding manual polysomnographic diagnonis. This system is composed of four sub parts: patient information management tool, polysomno-graphic signal acquisition tool, signal analysis tool, and result-reporting tool. We calculated the parameters of sleep diagnosis, both on the sleep stage hypnogram and event lists. We developed this system on the Windows NT 4.0 and Pentium Pro 200Mhz. We are testing this system on the clinical site.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.27-30
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• 1996

PR interval variability has been proposed as a noninvasive tool for in-vestigating the autonomic nervous system as welt as heart rate variability. The goal of this paper is to determine whether PR interval variability is generated from deterministic nonlinear dynamics. The data used in this study is a 24-hour bolter ECGs of 20 healthy adults. We developed an automatic PR interval measurement algorithm, and tested it using MIT ECG Databases. The general discriminants of nonlinear dynamics, such as, correlation dimension and phase space reconstruction are used. Surrogate data is generated from simpler linear models to have similar statistical characteristics with the original data. Nonlinear discriminants are applied to both data, and compared for any significant results. It was concluded that PR interval variability shows non-linear characteristics.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.10-13
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• 1996

We have developed the digital polysomnograph system to enhance the manual sleep study. This system is composed of host PC and target board. The host computer is IBM-PC Pentium 133 MHz and the target board is PC31 (processor type: TMS320C31). These two Processors communicate with each other by dualport RAM. Target board acquire 16 channel sleep signals from the Polysomnographic system (GRASS model 78, USA) and digitize them. We used high resolution monitor$(1600{\times}1280)$ to simulate the paper-recording quality of polysomnographic signal. We also implemented the GUI based polysomnographic staging program on the windows environment. Clinicians can score the sleep stage, and edit and mark the event efficiently. Finally it can support making patient database.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.169-175
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• 1993

Recently, interest in infra-red(IR) telemetry has increased because of the entirely different propagation and reflection properties of IR light as compared to radiowaves. IR hardly penetrates most materials and is reflected from obstacles. An biotelemetry system using these characteristics of indirect transmitted IR lights was developed, in which 3 ECG's are multiplexed and modulated in PDM/PIM pulse sequence. This proto-type system enables us to realize the non-restraint measurement of biological signals. Compared with conventional radio telemetry, this technique has some merits such as no electromagnetic interference, no frequency allocation problem, no government control over transmission power.