• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1048-1057
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• 2012

In this paper, a new compact dual-band unequal power divider is suggested. Instead of the quarter wavelength transmission line(TX-line)s for the branches of the conventional Wilkinson's power divider, we use composite right- and left-handed(CRLH) phase-shift lines and can reduce the physical length. With the non-linear dispersion of the meta-meterial, each branch in the proposed divider is designed to have $+90^{\circ}$ and $-90^{\circ}$ at $f_1$ and $f_2$ respectively. To validate the proposed method, the performances of the circuit and full-wave simulation results are shown with the CRLH dispersion curve. The measurement results are compared with the simulation results. Also, the size reduction effect by the proposed scheme is addressed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.162-172
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• 2011

In this paper, a design and fabrication of 4 W power amplifier for the WiMAX frequency band(2.3~2.7 GHz) are presented. The adopted active device is a commercially available GaN HEMT chip of Triquint Company, which is recently released. The optimum input and output impedances are extracted for power amplifier design using a specially self-designed tuning jig. Using the adopted impedances value, class-F power amplifier was designed based on EM simulation. For integration and matching in the small package module, spiral inductors and interdigital capacitors are used. The fabricated power amplifier with $4.4{\times}4.4\;mm^2$ shows the efficiency above 50 % and harmonic suppression above 40 dBc for second(2nd) and third(3rd) harmonic at the output power of 36 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1447-1453
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• 2010

In this paper, the design and the fabrication of dual-band bandpass filter using two dual-mode resonators is presented. Dual-mode resonator using a short stub is miniaturized by inter-digital capacitor and stepped impedance. Two dual mode resonators are designed to have different resonant frequencies, one for the lower passband and the other for the upper passband. Transmission zero is positioned at low or high rejection bands with a sharp skirt characteristic. Dual-band operation can be achieved using dual feeding structure. For WLAN, the proposed filter at 2.45/5.25 GHz is designed and fabricated. The size of the filter is as compact as 1$10.83\;mm{\times}5.3\;mm$.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.54.1-54.1
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• 2014

Kyung Hee University has been developing a CubeSat for the space science mission called SIGMA (Scientific cubesat with Instrument for Global Magnetic field and rAdiation), which includes TEPC (Tissue Equivalent Proportional Counter) and a magnetometer. SIGMA has a 3-unit CubeSat, and the weight is about 3.2 kg. The main payload is TEPC which can measure the Linear Energy Transfer (LET) spectrum and calculate the equivalent dose for the complicated radiation field in the space. The magnetometer is a secondary payload using a miniaturized fluxgate magnetometer. We expect it to have a 1 nT resolution in the dynamic range of ${\pm}65535$ nT. An Attitude Control System (ACS) spins the SIGMA spacecraft 4 rpm with the spin axis perpendicular to the ecliptic plane. Full duplex communication is consists of VHF uplink and S-band and UHF downlink. In this paper, we introduce the system design and the scientific purpose of the SIGMA CubeSat mission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1429-1435
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• 2004

In this work, high performance broadband amplifier MMIC including all the matching and biasing components, and electrostatic discharge (ESD) protection circuit was developed for K/Ka band applications. Therefore, external biasing or matching components were not required for the operation of the MMIC. STO (SrTiO3) capacitors were employed to integrate the DC biasing components on the MMIC, and miniaturized LC parallel ESD protection circuit was integrated on MMIC, which increased ESD breakdown voltage from 10 to 300 V. A pre-matching technique and RC parallel circuit were used for the broadband design of the amplifier MMIC. The amplifier MMIC exhibited good RF performances and good stability in a wide frequency range. The chip size of the MMICs was $1.7{\pm}0.8$ mm2.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.251-258
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• 2010

This paper presents the technology for the design, fabrication, and characterization of a microfluidic system interface (MSI); the purpose of this technology is to enable the integration of complex microfluidic systems. The MSI technology can be applied in a simple manner for realizing complex arrangements of microfluidic interconnects, integrated microvalves for fluid control, and optical windows for on-chip optical processes. A microfluidic system for the preparation of genetic samples was used as the test vehicle to prove the effectiveness of the MSI technology for packaging complex microfluidic systems with multiple functionalities. The miniaturized genetic sample preparation system comprised several functional compartments, including compartments for cell purification, cell separation, cell lysis, solid-phase DNA extraction, polymerase chain reaction, and capillary electrophoresis. Additionally, the functional operation of the solid-phase extraction and PCR thermocycling compartments was demonstrated by using the MSI.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.62-68
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• 1990

On the basis of standard Si processing, the miniaturized piezoresistive-type Si pressure sensor with a chip size of $1.7{\times}1.7{mm^2}$ was fabricated and its operating characteristics were investigated. The sensor chip has a full-bridge type of 4 boron-diffused resistors which is formed on an $1.0{\times}1.0{mm^2}$ area, $20{\mu}m$ thick n-type Si diaphragm and finally, encapsulated under room temperature, 1 atm in order to measure a gauge pressure. The operating characteristics of this sensor were determined as a pressure sensitivity of $14.2{\mu}$V/VmmHg, a rated pressure range of 0~760 mmHg, and a maximum nonlinearity of $1.0{\%}$ FS at room temperature.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.104-109
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• 2020

In this paper, we proposed a miniaturized folded inverted F antenna with ISM-band (center frequency : 447 MHz) for mounting in intelligent parking sensor. First, to mount the antenna in the intelligent parking sensor module (72 mm × 70 mm) with limited size, a folded inverted F antenna was designed at low frequency 447 MHz (wavelength λ : 670 mm) of the ISM-band. As a result, it resonates in the ISM band and obtains suitable characteristic with a -10 dB bandwidth of 13 MHz (2.9%). In addition, the H-plane pattern by the vertical and horizontal elements represents the omni-directional patterns from which the null point is removed, and the E-plane has directivity in a specific direction. Finally, it is suitable as and antenna for vehicle management in parking lots.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.669-677
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• 2016

A miniaturized FTIR spectrometer based on lamellar grating interferometry is being developed for passive remote-sensing. Consisting of a pair of micro-mirror arrays, the lamellar grating can be fabricated using MEMS technology. This paper describes a method to compute the optical field in the interferometer to optimize the design parameters of the lamellar grating FTIR spectrometer. The lower limit of the micro-mirror width in the grating is related to the formation of a Talbot image in the near field and is estimated to be about $100{\mu}m$ for the spectrometer to be used for the wavelength range of $7-14{\mu}m$. In calculating the far field at the detection window, the conventional Fraunhofer equation is inadequate for detection distance of our application, misleading the upper limit of the micro-mirror width to avoid interference from higher order diffractions. Instead, the far field is described by the unperturbed plane-wave combined with the boundary diffraction wave. As a result, the interference from the higher order diffractions turns out to be negligible as the micro-mirror width increases. Therefore, the upper limit of the micro-mirror width does not need to be set. Under this scheme, the interferometer patterns and their FT spectra are successfully generated.

• KSBB Journal
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• v.22 no.6
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• pp.378-386
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• 2007

Bio-sensing devices, which are basically integrated and miniaturized assay systems consisted of bioreceptor and signal transducer, are advantageous in several ways. In addition to their high sensitivity, selectivity, simplicity, multi-detection capability, and real time detection abilities, they are both very small and require relatively inexpensive equipments. Two core technologies are required to develop bio-sensing devices; the fabrication of biological receptor module (both of receptor development and immobilisation of them) and the development of signal transducing instruments containing signal generation technique. Various biological receptors, such as enzymes, DNA/RNA, protein, and cell were tried to develop bio-sensing devices. And, the signal transducing instruments have also been extensively studied, especially with regard to electrochemical, optical, and mass sensitive transducers. This article addresses bio-sensing devices that have been developed in the past few years, and also discusses possible future major trends in these devices.