• KSBB Journal
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• v.9 no.2
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• pp.174-179
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• 1994

Chitin was isolated from crab shell wastes and characterized for its chemical and physical properties. White powdered chitin was obtained through demineralizaticn, deproteinization and decoloration process. The contents of inorganics was less than 0.5%, whereas protein and lipid were almost removed. The results of IR spectroscopic analysis for the isolated chitin showed similar characteristics with that of Sigma product. Degree of deacetylation of purified chitin was significantly higher than Sigma product and viscosity average molecular weights was $2.3{\times}10^5~3.2{\times}10^5$. SEM analysis showed that the obtained chitin had the fibril shaped morphology.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.147-150
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• 2004

Graphite reinforced conductive polymer composites were fabricated by the compression molding technique. Graphite powder (conductive filler) was mixed with an epoxy resin to impart electrical property in composites. The ratio of graphite powder was varied to investigate electrical property of cured conductive composites. In this study, graphite filled conductive polymer composites with high filler loadings$(>60wt.\%)$ were manufactured to accomplish high electrical conductivity(> 100S/cm). Graphite powder increase electrical conductivity of composites by direct physical contact between particles. While high filler loadings are needed to attain good electrical property, the composites becomes brittle. So the ratio of filler to epoxy was varied to optimize of cured composites. The optimum molding pressure according to filler was proposed experimentally.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.103-105
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• 2003

A chiral stationary phase (CSP) was synthesized by the modification of the chitosan using N-nicotinoyl phenylalanine and 3, 5-dimethylphenylisocyanate . The CSP based on the chitosan was then characterized in terms of their chemical structure and physical properties. To test its performance as a CSP, the silica powder with 5 ${\mu}{\textrm}{m}$ of diameter were coated with the CSP to pack a column for High Performance Liquid Chromatograph (HPLC). Using the packed column, several racemates were tried to separate under various separation conditions with different compositions of eluents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.13-22
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• 1999

Both the resonance and ultrasonic techniques are standard methods far characterizing the physical properties of piezoelectric materials. However, we found that each technique can only offer a few reliable measurements while the rest often have errors or impossible to implement because of the sample requirements. This paper show that one can use the combination of both techniques to achieve much better accuracy and be able to get the complete set of elastic, dielectric and piezoelectric coefficients using fewer samples. Using an ultrasonic spectroscopy we have also measure the dispersion of the ultrasonic velocity and the attenuation up to 65 MHz. Pb(Zr,Ti)O$_3$[PZT] ceramics were used as examples fur both studies.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.197-202
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• 1999

Electric arc furnaces (EAFs) use bulk electrical energy to create heat in metal refining industries. The electric arc process is a main cause of the degradation of the electric power quality such as voltage flicker due to the interaction of the high demand currents of the load with the supply system impedance. The stochastic models have described the aperiodic physical phenomena of EAFs. An alternative approach is to include deterministic chaos in the characterization of the arc currents. In this parer, a chaotic approach to such modeling is described and justified. At the same time, a DLL(Dynamic Link Library) module, which is a FORTRAN interface with TACS (Transient Analysis of Control Systems), is developed to implement the chaotic load model in the Electromagnetic Transients Program (EMTP). The details of the module and the results of tests performed on the module to verify the model and to illustrate its capabilities are presented in this paper.

• Genomics & Informatics
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• v.4 no.2
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• pp.80-86
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• 2006

It is clear that the construction of large insert DNA libraries is important for map-based gene cloning, the assembly of physical maps, and simple screening for specific genomic sequences. The bacterial artificial chromosome (BAC) system is likely to be an important tool for map-based cloning of genes since BAC libraries can be constructed simply and analyzed more efficiently than yeast artificial chromosome (YAC) libraries. BACs have significantly expanded the size of fragments from eukaryotic genomes that can be cloned in Escherichia coli as plasmid molecules. To facilitate the isolation of molecular-biologically important genes in Ashbya gossypii, we constructed Ashbya chromosome-specific BAC libraries using pBeloBAC11 and pBACwich vectors with an average insert size of 100 kb, which is equivalent to 19.8X genomic coverage. pBACwich was developed to streamline map-based cloning by providing a tool to integrate large DNA fragments into specific sites in chromosomes. These chromosome-specific libraries have provided a useful tool for the further characterization of the Ashbya genome including positional cloning and genome sequencing.

• Microbiology and Biotechnology Letters
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• v.23 no.3
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• pp.249-254
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• 1995

When mating type A and a cells of heterobasidiomycetous yeast Rhodosporidium toruloides were mix-cultured, both of the mating type cells have shown strong agglutination. But this agglutination was not detactable when the A and a cell were cultured separately. From reagglutination made just after the result of disassembling the agglutination by sonication, we knew that the agglutination was sexual-agglutination, not simple physical cell agglutination. The sexual agglutination was progressed actively on logarithmic phase and, in addition, progressed faster on mating type a cell treated with rhodotorucine A. These sexual agglutination have been inhibited by several protease such as trypsin, pronase, chymotrpysin and thermolysin and inhibited by 5 mM DTT as well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.457-460
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• 2004

Many of the physical and chemical properties of polymer materials can be altered by high energy radiation. In the present work the exposure to radiation of low density polyethylene(LDPE) included antioxidants was carried out at various doses up to 600kGy at a dose rate of 5kGy/hr in the presence of air at room temperature. The study of the irradiation effects on the material properties has been make by different methods in an integrated way. The experimental data indicate that the decomposition onset temperature(DOT), the crystallinity and the thermoluminescence(TL) with radiation dose. DOT, crystallinity and TL analysis from irradiated PE samples provides useful data for the characterization of radiation-induced oxidation effects on these samples.

• Tunnel and Underground Space
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• v.6 no.1
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• pp.1-9
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• 1996

Pocheon granite specimens were thermally treated with cycles of predetermined temperatures ranging 2$0^{\circ}C$ to $600^{\circ}C$. Characterization of thermally-induced microcracks were carried out using optical microscopy and their effect on the various physical & mechanical properties were studied. Generally. uniaxial compressive strength, Young's modulus, Poisson's ratio, elastic wave velocity and specific gravity were found to decrease with increasing temperature. From 30$0^{\circ}C$ upwards, negative lateral strains were observed, which resulted in negative Poisson's ratio. Dynamic Young's modulus and Poisson's ratio were found to be generally most sensitive indicators to thermal cracking.

• Journal of the Korean Mathematical Society
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• v.41 no.1
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• pp.157-174
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• 2004

In this work we discuss "plank problems" for complex Banach spaces and in particular for the classical $L^{p}(\mu)$ spaces. In the case $1\;{\leq}\;p\;{\leq}\;2$ we obtain optimal results and for finite dimensional complex Banach spaces, in a special case, we have improved an early result by K. Ball [3]. By using these results, in some cases we are able to find best possible lower bounds for the norms of homogeneous polynomials which are products of linear forms. In particular, we give an estimate in the case of a real Hilbert space which seems to be a difficult problem. We have also obtained some results on the so-called n-th (linear) polarization constant of a Banach space which is an isometric property of the space. Finally, known polynomial inequalities have been derived as simple consequences of various results related to plank problems.