• KSBB Journal
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• v.25 no.4
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• pp.344-350
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• 2010

This paper demonstrates a microfluidic chip incorporating patterned hollow silica beads that can be effectively used for chemotaxis assay. The hollow silica bead has been exploited to develop a carrier for chemoattractant to induce cell migration. The microfluidic chip contains a patterned array of microfabricated docks which can hold only one bead per docking site. The hollow bead placed inside microfluidic chip releases chemotactic reagent (PDGF-BB) around its periphery in a controlled fashion which generates a signal for chemotatic migration of fibroblast cells. The number of cells migrated close to each bead has been assessed. On-chip cell migration assay showed a remarkable result proving the high efficiency and reliable accuracy in quantitative analysis. Therefore, the device could be extensively used in cell migration assay and other various studies related to cellular movements.

• Journal of Sensor Science and Technology
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• v.25 no.4
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• pp.243-246
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• 2016

The characteristics of a bimetallic surface plasmon resonance (SPR) chip were investigated to detect a tumor biomarker, carcinoembryonic antigen (CEA). The linewidth and the tangential slope of the reflectance curve of the bimetallic SPR chip was compared with those of the reflectance curve of a conventional gold (Au) SPR chip. The changes in reflectance in response to the variation in CEA in the critical concentration range were analyzed at an angle where the tangential slope of the reflectance curve was maximum. From linear regression analysis, the sensitivity of the bimetallic SPR chip with respect to the CEA in critical concentration was obtained.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.42-47
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• 2009

In this paper we propose a microfluidic chip that measures the mechanical stiffness of cell membrane using impedance measurement. The microfluidic chip is composed of PDMS channel and a glass substrate with electrode. The proposed device uses patch-clamp technique to capture and deform a target cell and measures impedance of deformed cells. We demonstrated that the impedance increased after the membrane stretched and blocked the channel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1140-1144
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• 2005

A plastic-based CE (capillary electrophoresis) microchip was fabricated by hot embossing process. A Si mold was made by wet etching process and a PMMA wafer was cut off from 1mm thick PMMA sheet. A micro-channel structure on PMMA substrate was produced by hot embossing process using the Si mold and the PMMA wafer. A vacuum assisted thermal bonding procedure was employed to seal an imprinted PMMA wafer and a blank PMMA wafer. The results of microscopic cross sectional images showed dimensions of channels were well preserved during thermal bonding process. In our procedure, the deformation amount of bonding process was below 1%. The entire fabrication process may be very useful for plastic based microchip systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.553-558
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• 1998

We present in this paper the ture union bound of the performance of chip level detection for coded DS/CDMA system operating in Rician fading channels such as LEO satellite mobile radio where the maximum doppler frequency is very high. The main objective of this paper is to calculate the exact doe union bound of BER performance of different performance of different quadrature detectors and to find a optimum spreading factor as a function of fade rate. The rationale of using multiple chip detection is to reduce the effective fade rate or variation. We considered chip level differential detection, chip level maximum likelihood sequence estimation, noncoherent detection and coherent detection with perfect channel state information as a reference.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.263-266
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• 2005

An UHF ($860{\sim}960MHz$) RFID tag antenna is optimized and designed using a genetic algorithm (GA). The tag antenna impedance should be matched to the conjugate of the impedance of the tag IC Chip. The chip impedance has real and capacitive imaginary parts due to the parasitic capacitance of the RFID chip. A GA linked with a commercially available antenna simulation program optimizes the UHF $860{\sim}960\;MHz$ tag antenna to match a commercially available RFID chip. This method shows that any RFID antenna can be designed for any commercial RFID chip with any impedance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1228-1235
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• 2014

Input impedance of UHF RFID tag chip is needed to design a tag. In determining the chip impedance, direct measurement method is adopted commonly. In this paper, problems generated from fixtures that interface between tag chip and coaxial-oriented measurement instrument are investigated and the result of the problems is shown, when the direct measurement method is applied. As an alternative to the method, a modeling method is proposed and its validity and accuracy are shown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.561-565
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• 2007

We propose glass and PDMS (polydimethylsiloxane) chips for DNA amplification with continuous-flow PCR (polymerase chain reaction). The PDMS microchannel was fabricated using a negative molding method for sample injection. Three heaters and sensors of ITO (indium-tin-oxide) thin films were fabricated on glass chip. ITO heaters and sensors were calibrated accurately for the temperature control of the liquid flow. ITO heater generated stable heat versus applied power. ITO sensor resistance was changed linearly versus temperature increase as a RTD (resistance temperature detector) sensor. As a result, we enable precision temperature control of continuous-flow PCR chip. Using the continuous-flow PCR chip DNA plasmid pKS-GFP 720 bp was successfully amplified.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1673-1678
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• 2007

The use of flip-chip type electronic package offers numerous advantages such as reduced thickness, improved environmental compatibility, and downed cost. Despite numerous benefits, flip-chip type packages bare several reliability problems. The most critical issue among them is their electrical performance deterioration upon consecutive thermal cycles attributed to gradual delamination growth through chip and adhesive film interface induced by CTE mismatch driven shear and peel stresses. The electronic package in use is heated continuously by itself. When the crack at a weak site of the electronic package occurs, thermal deformationon the chip side is changed. Therefore, we can measure these micro deformations by using Moire interferometry and find out the crack length.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.32-38
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• 2005

Generally, cutting force models use a sin function method to calculate chip thickness. In slot end milling, the error from a sin function method is much bigger than other machining because a tool rotation angle in cutting is much larger. Thus in this paper, a new method to calculate chip thickness was suggested and evaluated. In a new method, tool position data according to tool rotation are checked and stored so that it is possible correct chip thickness is calculated. Cutting force waveforms simulated from a sin function method and a new method and measured waveforms from experiments were compared and error percentages were obtained. Finally, a new method had good results for simulating cutting force in slot end milling.