• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.1-12
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• 2003

DAB(Digital audio broadcasting) is a next generation radio broadcasting system which provides CD quality audio, various data services and superior reception ability when moving. Also, it can show traffic informations and news literally or graphically. In this paper, we design and fabricate the DAB tuner for ITS service that follows Eureka-147 and ETSI 300 401 specifications. This small-sized tuner can be adopted to mny electronic equipments such as a Hi-Fi audio, DVD player, car audio system etc.. The overall performance of the tuner depends on a phase noise of VCO and the sensitivity of the receiving system is influenced by LNA, image rejection filter and channel selection filter. All our measurement results satisfy the specification for a DAB system with the return loss of 9dB, the noise figure of 6dB for both Band 111 and L-band and the sensitivity of -97dBm.

• 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$10.83\;mm{\times}5.3\;mm$.

• Publications of The Korean Astronomical Society
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• v.27 no.3
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• pp.71-80
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• 2012

We have developed superconducting mixer receivers for 129 GHz VLBI observation in Korean VLBI Network (KVN). The developed mixer has a radial waveguide probe with simple transmission line L-C transformer as a tuning circuit to its 5 series-connected junctions, which can have 125 - 165 GHz as the operation radio frequency (RF). For intermediate frequency (IF) signal path a high impedance quarter-wavelength line connects the probe to one end of symmetric RF chokes. The double side band (DSB) receiver noise of the mixer was about 40 K over 4 - 6 GHz IF band, whereas we achieved the uncorrected single side band (SSB) noise temperature of about 70 K and better than 10 dB image rejection ratio in 2SB configuration with 8 - 10 GHz IF band. Insert-type receiver cartridges employing the mixers have been under commission for KVN stations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.918-923
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• 2009

In this paper, a design method of the compact narrow band filter on the microstrip board is proposed using complementary split-ring resonators(CSRRs). The design technique of this filter is based on cascading filter stages consisting of the combination of circular CSRRs, capacitive gaps between patches, and inductive grounded stubs with the meander configuration. By these means, it was possible to get the nearly symmetric frequency responses, adjustable bandwidths, compact sizes. And also excellent characteristic of the out-of-band rejection is achieved in contrast to the conventional filter design technique. The measured insertion shows good results about -4.0dB at the center frequency($f_0=1GHz$) and passband return loss is less than -9.4dB. The 3dB fractional bandwidth(FBW) is approximately 4%. The results of the frequency response measured on the fabricated band pass filter substrate show satisfactory agreement with the simulated frequency responses by the HFSS in the region of interest.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.36-44
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• 2016

In this paper, an Impulse Radio-Ultra Wide band RF Transceiver for WBAN applications is implemented in $0.18{\mu}m$ CMOS technology. The designed RF transceiver support 3-5GHz UWB low band and employs OOK(On-Off Keying) modulation. The receiver employs non-coherent energy detection architecture to reduce complexity and power consumption. For the rejection of the undesired interferers and improvement of the receiver sensitivity, RF active notch filter is integrated. The VCO based transmitter employs the switch mechanism. As adapt the switch mechanism, power consumption and VCO leakage can be reduced. Also, the spectrum mask is always same at each center frequency. The measured sensitivity of the receiver is -84.1 dBm at 3.5 GHz with 1.579 Mbps. The power consumption of the transmitter and receiver are 0.3nJ/bit and 41 mW respectively.

• Journal of computational fluids engineering
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• v.13 no.2
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• pp.48-54
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• 2008

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be launched by ARIANE 5. Ka-band components are installed on South panel, where single solar array wing is mounted. Radiators, embedded heat pipes, external heat pipe, insulation blankets and heaters are utilized for the thermal control of the satellite. The Ka-band payload section is divided several areas based on unit operating temperature in order to optimize radiator area and maximize heat rejection capability. Other equipment for sensors and bus are installed on North panel. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. During the transfer orbit operation, satellite will be under severe thermal environments due to low dissipation of components, satellite attitudes and LAE(Liquid Apogee Engine) firing. This paper presents temperature and heater power prediction and validation of thermal control design during transfer orbit operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1156-1160
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• 2000

The cancellation loop configuration for power amplifier module is proposed to reject the RX signals using feed-forward technique. In this paper, we implement the 1W-ampilfier module of WLL band to show validity of the proposed cancellation loop. The power amplifier module with the proposed cancellation loop can provide low TX insertion path loss due to duplexer and choice of loose RX attenuation characteristic for various wireless communication systems. It shows at least 90 % improved RX rejection characteristic compared to power amplifier module without RX band cancellation loop.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.92-98
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• 2010

A new wideband bandstop filter(BSF) with a sharp roll-off characteristic is introduced in a stripline structure in this paper. The BSF consists of two sections: the first is two capacitively coupled $\lambda/4$ short-circuited lines with opposite ground positions, while the second is a capacitively coupled $\lambda/4$ short-circuited line. The BSF provides three transmission zeros within the stopband and better than 22 dB rejection over the whole wireless local area network (WLAN) band from 5.15 to 5.825 GHz. The BSF, cascaded to an U.S. ultra-wideband(UWB: 3.1~10.6 GHz) band-pass filter(BPF), is simulated with HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape with a dielectric constant of 7.8. The measurement results agree well with the HFSS simulation results. The size of the UWB BPF including the BSF is $3{\times}6.3\times0.45\;mm^3$.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.550-557
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• 2006

This paper proposes a dry-type surface myoelectric sensor for the myoelectric hand prosthesis. The designed surface myoelectric sensor is composed of skin interface and processing circuits. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper is proposed two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22mm is selected. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value(MAV) circuit. Using SUS440, six prototype skin interface with different reference electrode shape and IED is fabricated, and their output characteristics are evaluated by output signal obtained from the forearm of a healthy subject. The experimental results show that the skin interface with parallel bar shape and the 18mm IED has a good output characteristics. The fabricated dry-type surface myoelectric sensor is evaluated for the upper-limb amputee.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.227-231
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• 2007

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication and ocean and meteorological observations. It will be launched by ARIANE 5. Ka-band components are installed on South panel, where single solar array wing is mounted. Radiators, embedded heat pipes, external heat pipe, insulation blankets and heaters are utilized for the thermal control of the satellite. The Ka-band payload section is divided several areas based on unit operating temperature in order to optimize radiator area and maximize heat rejection capability. Other equipment for sensors and bus are installed on North panel. The ocean and meteorological sensors are installed on optical benches on the top floor to decouple thermally from the satellite. During the transfer orbit operation, satellite will be under severe thermal environments due to low dissipation of components, satellite attitudes and LAE(Liquid Apogee Engine) firing. This paper presents temperature and heater power prediction and validation of thermal control design during transfer orbit operation.