• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1135-1139
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• 2004

This paper presents a microextractor for the separation of DNA molecules by their sizes. The DNA microextractor immobilizes the DNA molecules of specific size in the micropillar array by adjusting the period of the crossed electric field, thus providing a starting-point independent target DNA extraction method without separation process monitoring. The DNA microextractor has been fabricated by a three-mask micromachining process. The velocity of three different DNA molecules has been measured at the electric field of E=5V/0.8cm in the fabricated DNA microextractor, resulting in the reorientation times of $4.80{\pm}0.44sec,\;7.12{\pm}0.75sec$, and $9.88{\pm}0.30sec$ for ${\lambda}$ DNA, micrococcus DNA, and T4 DNA, respectively. T4 DNA is trapped in the micropillar array when the crossed electric field of 5V/0.8cm is applied alternately at a 10 second time interval. The present DNA microextractor filters the DNA in a specific size range by adjusting the magnitude and/or the period of the crossed electric field applied in the micropillar array.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.265-268
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• 2009

We present the experimental study to realize a DNA separation chip using asymmetrically-switched nonuniform electric fields. The DNA separation chip redistributes DNA molecules within a specific area based on the size- and field-dependent nonlinearity of DNA drift velocity. The present chip is composed of a width variable channel to distribute nonuniform electric field, a DNA loading slit and a pair of electrodes to apply electric field. We focus on the design of DNA separation chips with identifying the nonlinearity of DNA drift velocity using three different DNA molecules (11.1kbp, 15.6kbp, and 48.5kbp) in the chips. It is demonstrated that different size of DNA shows different net migration in different direction under the asymmetrically-switched nonuniform electric field.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.391-395
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• 2012

We present a continuous cell separator that achieves density-dependent and size-independent cell separation based on the net force of gravity and buoyancy forces on the cells in dissimilar density fluids. Previous cell separators are, based on the size or dielectrophoretic property of the cells and, are suitable for size-dependent and density-independent cell separation. However, these properties can make it difficult to collect the same types of cells with the same density but with size variations. The present separator, however, is capable of collecting the same types of cells based on the cell density in the fluid. Regardless of cell size, the proposed chip isolates low density cells, (white blood cells, or WBCs) at the upper outlet while obtaining high-density cells (red blood cells, or RBCs) from the lower outlet based on density. Efficiency levels for separation of WBCs and RBCs were $90.9{\pm}9.1%$ and $86.4{\pm}1.99%$, respectively. The present separator therefore has the potential for use in the pretreatment of whole blood.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.378-385
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• 2021

The production of plum jangachi requires the cleaning of plums, immersion in saltwater, separation of seed and pulp, removal of impurities, and addition of sugar. In most farms, the separation of plum seed and pulp is carried out manually, requiring considerable labor, which is why plum jangachi is expensive. To solve this problem, this study designed and manufactured automatic, semi-automatic plum seed and pulp separators. During the design process, the characteristics were compared, and the machine power was determined through on-site test after manufacture. As a result, automatic machines used plums 180° arrayed and six reverse-edged blades, semi-automated plums 180° arrayed, and six blades, each with a 68% and 57% pulp recovery rate and a machine power of 80 kg/h and 62 kg/h respectively. Overall, the mechanization of plum processed food will reduce labor and increase the market value of plums compared to the previous method.