• KSBB Journal
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• v.24 no.5
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• pp.432-438
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• 2009

Here, we demonstrated simple nucleic acid, RNA, concentration method using polymer micro chip containing glass bead ($100\;{\mu}m$). Polymer micro chip was fabricated by PDMS ($1.5\;cm\;{\times}\;1.5\;cm$, $100\;{\mu}m$ in the height) including pillar structure ($160\;{\mu}m\;(I)\;{\times}\;80\;{\mu}m\;(w)\;{\times}\;100\;{\mu}m\;(h)$, gap size $50\;{\mu}m$) for blocking micro bead. RNA could be adsorbed on micro glass bead at low pH by hydrogen bonding whereas RNA was released at high pH by electrostatic force between silica surface and RNA. Amount of glass beads and flow rate were optimized in aspects of adsorption and desorption of RNA. Adsorption and desorption rate was measured with real time PCR. This concentrated RNA was applied to amplification micro chip in which NASBA (Nucleic Acid Sequence Based Amplification) was performed. As a result, E.coli O157 : H7 in the concentration of 10 c.f.u./10 mL was successfully detected by these serial processes (concentration and amplification) with polymer micro chips. It implies this simple concentration method using polymer micro chip can be directly applied to ultra sensitive method to measure viable bacteria and virus in clinical samples as well as environmental samples.

• Journal of KIISE:Databases
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• v.34 no.2
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• pp.109-118
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• 2007

Recently, flash memory is used to store data in mobile computing devices such as PDAs, SmartCards, mobile phones and MP3 players. These devices need index structures like the B-tree to efficiently support some operations like insertion, deletion and search. The BFTL(B-tree Flash Translation Layer) technique was first introduced which is for implementing the B-tree on flash memory. Flash memory has characteristics that a write operation is more costly than a read operation and an overwrite operation is impossible. Therefore, the BFTL method focuses on minimizing the number of write operations resulting from building the B-tree. However, we indicate in this paper that there are many rooms of improving the performance of the I/O cost in building the B-tree using this method and it is not practical since it increases highly the usage of the SRAM memory storage. In this paper, we propose a BOF(the B-tree On Flash memory) approach for implementing the B-tree on flash memory efficiently. The core of this approach is to store index units belonging to the same B-tree node to the same sector on flash memory in case of the replacement of the buffer used to build the B-tree. In this paper, we show that our BOF technique outperforms the BFTL or other techniques.