• Journal of the Optical Society of Korea
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• 제10권3호
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• pp.130-142
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• 2006

Lab-on-a-chip technology is attracting great interest because the miniaturization of reaction systems offers practical advantages over classical bench-top chemical systems. Rapid mixing of the fluids flowing through a microchannel is very important for various applications of microfluidic systems. In addition, highly sensitive on-chip detection techniques are essential for the in situ monitoring of chemical reactions because the detection volume in a channel is extremely small. Recently, a confocal surface enhanced Raman spectroscopic (SERS) technique, for the highly sensitive biological analysis in a microfluidic sensor, has been developed in our research group. Here, a highly precise quantitative measurement can be obtained if continuous flow and homogeneous mixing condition between analytes and silver nano-colloids are maintained. Recently, we also reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). This method overcomes many of the drawbacks of microarray chips, such as long hybridization times and inconvenient immobilization procedures. In this paper, our recent applications of the confocal Raman/fluorescence microscopic technology to a highly sensitive lab-on-a-chip detection will be reviewed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.360-365
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• 2003

In this paper, we have developed a general purpose motion controller using an FPGA(Field Programmable Gate Array). The multi-PID controllers on a single chip are implemented as a system-on-chip for multi-axis motion control. We also develop a PC GUI for an efficient interface control. Comparing with the commercial motion controller LM 629 it has multi-independent PID controllers so that it has several advantages such as space effectiveness, low cost and lower power consumption. In order to test the performance of the proposed controller, robot finger is controlled. The robot finger has three fingers with 2 joints each. Finger movements show that position tracking was very effective. Another experiment of balancing an inverted pendulum on a cart has been conducted to show the generality of the proposed FPGA PID controller. The controller has well maintained the balance of the pendulum.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.965-966
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• 2006

As billion transistors system-on-chip (SoC) design becomes a reality, the productivity gap between rapidly increasing design complexity and designer productivity lagging behind is becoming a more serious problem to be solved. To reduce the gap, we present a system that generates executable transaction level models automatically. It speed up the SoC design space exploration process at various abstraction levels.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.203-207
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• 1999

In this paper we report new integration technology developed for three-dimensional metallic microstructures in an arbitrary shape. We have developed the two fabrication methods: Multi-Exposure and Single-Development (MESD) and Sacrificial Metallic Mold(SMM) techniques. Three-dimensional photoresist mold can be formed by the MESD method while unlimited number of structural levels can be realized by the SMM technique. Using these two techniques we have fabricated solenoid inductors and levitated spiral inductors for RF applications. We have achieved peak Q- factors over 40 in the 2-10㎓ range, the highest number among the inductors reported to date. Finally, we propose "On-Chip Passives" as a post IC process for monolithic integration of inductors, tunable capacitors, microwave switches, transmission lines, and mixers and filters toward future single-chip transceiver integration.

• 한국융합학회논문지
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• 제9권3호
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• pp.217-222
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• 2018

본 논문에서는 정확한 수의 희귀 세포 포집 및 이송을 위한 마이크로 폴리머 칩 플랫폼의 디자인과 제작, 그리고 프로토콜을 소개하고 있다. 본 플랫폼과 프로토콜은 기존의 통계학적인 샘플 준비 방법인 희석(Dilution)의 한계와 고가이며 형광염색이 요구되는 유세포분석기(Fluorescence activated cell sorter)의 단점을 극복하였다. 타켓 세포를 선택적으로 쉽고 간단하게 채집할 수 있으며 채집되는 세포의 수는 시각적으로 검증되므로 매우 정확한 방법이다. 또한, 채집된 세포들은 마이크로 챔버 등의 원하는 곳으로 세포의 손실 없이 이송 또는 주입 시킬 수 있다. 본 연구는 암진단 등을 목적으로 하는 칩 속의 실험실(Lab on a chip) 등에 필요한 희귀 세포 샘플 준비를 위해 활용 될 수 있을 뿐만 아니라 세포분석을 위한 싱글/더블/다수 세포 샘플의 준비에도 활용 가능하다. 본 논문에서 제시하는 세포 채집 플랫폼과 프로토콜을 검증하기 위해 5개의 인간 암세포(MCF-7)를 채집한 뒤 세포계수기(Hemocytometer) 안으로 주입시켜 세포의 수를 확인하였다.

• Applied Science and Convergence Technology
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• 제24권5호
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• pp.196-202
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• 2015

Human blood consists of 55% of plasma and 45% of blood cells such as white blood cell (WBC) and red blood cell (RBC). In plasma, there are many kinds of promising biomarkers, which can be used for the diagnosis of various diseases and biological analysis. For diagnostic tools such as a lab-on-a-chip (LOC), blood plasma separation is a fundamental step for accomplishing a high performance in the detection of a disease. Highly efficient separators can increase the sensitivity and selectivity of biosensors and reduce diagnostic time. In order to achieve a higher yield in blood plasma separation, we propose a novel fluid wing structure that is optimized by COMSOL simulations by varying the fluidic channel width and the angle of the bifurcation. The fluid wing structure is inspired by the inertial particle separator system in helicopters where sand particles are prevented from following the air flow to an engine. The structure is ameliorated in order to satisfy biological and fluidic requirements at the micro scale to achieve high plasma yield and separation efficiency. In this study, we fabricated the fluid wing structure for the efficient microfluidic blood plasma separation. The high plasma yield of 67% is achieved with a channel width of $20{\mu}m$ in the fabricated fluidic chip and the result was not affected by the angle of the bifurcation.

• 센서학회지
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• 제18권1호
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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.

• 대한기계학회논문집B
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• 제30권2호
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• pp.110-116
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• 2006

A syringe pump or a device using high electric voltage has been used for controlling flows inside a LOC (lab-on-a-chip). Compared to LOC, however, these microfluidic devices are large and heavy that they are burdensome for a portable ${\mu}-TAS$ (micro total analysis system). In this study, a new flow control technique employing pressure regulators and pressure chambers was developed. This technique utilizes compressed air to control the micro-scale flow inside a LOC, instead of a mechanical actuator or an electric power supply. The pressure regulator controls the output air pressure by adjusting the variable resistor attached. We checked the feasibility of this system by measuring the flow rate inside a capillary tube of $100{\mu}m$ diameter in the Re numbers ranged from 0.5 to 50. In addition, the performance of this flow control system was compared with that of a conventional syringe pump. The developed flow control system was found to show superior performance, compared with the syringe pump. It maintains automatically the: air pressure inside a pressure chamber whether the flow inside the capillary tube is on or off. Since the flow rate is nearly proportional to the resistance, we can control flow in multiple microchannels precisely. However, the syringe pump shows large variation of flow rate when the fluid flow is blocked in the microchannel.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.228-230
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• 2002

We present a new low power scan testing and test data compression method for System-On-a-Chip (SOC). The don't cares in unspecified scan vectors are mapped to binary values for low power and encoded by adaptive encoding method for higher compression. Also, the scan-in direction of scan vectors is determined for low power. Experimental results for full-scanned versions of ISCAS 89 benchmark circuits show that the proposed method has both low power and higher compression.

• ETRI Journal
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• 제35권2호
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• pp.340-343
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• 2013

A novel bumping process using solder bump maker is developed for the maskless low-volume solder on pad (SoP) technology of fine-pitch flip chip bonding. The process includes two main steps: one is the aggregation of powdered solder on the metal pads on a substrate via an increase in temperature, and the other is the reflow of the deposited powder to form a low-volume SoP. Since the surface tension that exists when the solder is below its melting point is the major driving force of the solder deposit, only a small quantity of powdered solder adjacent to the pads can join the aggregation process to obtain a uniform, low-volume SoP array on the substrate, regardless of the pad configurations. Through this process, an SoP array on an organic substrate with a pitch of $130{\mu}m$ is successfully formed.