• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.189-192
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• 2004

A LNA module, integrated microwave assemblies (IMAs) were developed for use in Ka-band Satellite Communication Satellite Payload that operates in the frequency range of 29,6 ${\~}$ 30.0GHz. The module will be placed directly behind their respective antenna feed horns to minimize the required waveguide and system noise figure impact. Two MMIC LNA Chips were used in the module design. The measured result shows that the module has 32dB gain and 2.4dB NF performance. The module size is 51m ${\times}$ 36m ${\times}$ 22 and the mass is 92g. The Noise Figure performance is the best result of currently available modules for satellite payload operating in the same frequency range. The module will be assembled using space-qualified process and tested for space qualification.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.12-24
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• 2001

The key advantage of LTCC(low temperature co-fired ceramics) technology is the ability to integrate passive components such as resistors, capacitors, and inductors. More compact circuits with an increased scale of integration are needed with the development for advanced telecommunication system such as IMT-2000. LTCC technology can be obtained by removing these elements from the substrate surface to inside of ceramic body. And it can miniaturize the wireless phone through integration of planar patch antenna, duplexer, band pass filter, bias line, circuit of impedance matching and RF choke etc. Futhermore, with the multilayer chip process and its outstanding electrical material characteristics, LTCC is predestined for highly-integrated, cost effective wide band applications. This paper focuses on the general description of LTCC MCM technologies and the fabrication of the multilayer VCO module.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.35-42
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• 2010

We use conformal mapping method to derive the analytical expressions for calculating electrostatic fields and electric potentials surrounding the conductor-backed coupled coplanar waveguide(CBCCPW) structure. Using the derived expressions, the electrostatic fields and potentials are computed at various points of the CBCCPW's geometry and the field and potential distributions are analyzed. The proposed method provides a faster and simpler calculation of the field distributions than the full-wave analysis method because no iterations are required. This method can be widely applied to the analysis of microwave integrated circuits using coupled line, such as coupler, filter, and microstrip antenna.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.38-43
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• 1994

To provide more instructive and a safer ground control operation environments for satellite operators, and subsequently to implement a better look-and-feel user interface and a structural mechanism to enhance the efficiency of control and monitoring facilities, we have developed a prototype(laboratory model) ground control softwares targeting for the first generation KOREASAT scheduled to be launched in 1995. As far as the functionality is concerned, the developed system is covering almost all the mission phase operational functions except for some functions like antenna tracking control that are necessary for real operation environments. Most of the functions of the system is realized in softwares but some hardwares needed for TM/TC RF communications are also included in it. The system is now being integrated and under the system test. The performance and functionality is to be evaluated by the end of this year by using the satellite software simulator. Next year, this system could be configured to be used as a workbench for a online/off-line analysis of the operating KOREASAT satellites.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.619-628
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• 2012

The ZigBee network has been considered to monitor electricity usage of home appliances in the smart grid network. ZigBee, however, may suffer from a coexistence problem with wireless local area network (WLAN). In this paper, to resolve the coexistence problem between ZigBee network and WLAN, we propose a new protocol constructing a cognitive smart grid network for supporting monitoring of home appliances. In the proposed protocol, home appliances first estimates the transmission timing and channel information of WLAN by reading request to send/clear to send (RTS/CTS) frames of WLAN. Next, based on the estimated information, home appliances transmit a data at the same time as WLAN transmission. To manage the interference between WLAN and smart grid network, we propose a cognitive beamforming algorithm. The beamforming algorithm is designed to guaranteeing zero interference to WLAN while satisfying a required rate for smart metering. We also propose an energy efficient rate adaptation algorithm. By slowing down the transmission rate while satisfying an imperceptible impact of quality of service (QoS) of the receiver, the home appliance can significantly save transmit power. Numerical results show that the proposed multiple antenna technique provides reliable communications for smart metering with reduced power comparing to the simple transmission technique.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.535-544
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• 2008

Unlike MS(Magnetic Stripe), SMART CARD is equipped with COS(Chip Operating System) consisting of the Microprocessor and Memory where information can be stored and processed, and there are two types of cards according to the contact mode; the contact type that passes through a gold plated area and the contactless one that goes through the radio-frequency using an antenna embedded in the plastic card. the contactless IC card used for the transportation card was first introduced into local area buses in Seoul, and expanded throughout the country so that it has removed the inconvenience such as possession of cash, fare payment and collection. Focusing on the Seoul metropolitan area in 2004, prepaid and pay later cards were adopted and have been used interchangeably between a bus and subway. The card terminal compatible between a bus and subway is Proximity Integrated Circuit Card(PICC) as international standards(1443 Type A,B), communicates in the 13.56MHz dynamic frequency modulation-demodulation system, and adopts the Multi Secure Application Module(SAM). In the second half of 2009, the system avaliable nationwide will be built when the payment SAM standard is implemented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.949-958
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• 2016

This paper presents the new development result of the multi-band, the multi-mode SDR(Software Defined Radar) platform. The SDR hardware platform is implemented by using the reconfigurable multi-band RF transceiver and antenna modules of S, X, and K-bands, and a programmable signal processing module. The SDR software platform is implemented by using the multi-mode waveform generation of CW, Pulse, FMCW, and LFM Chirp as well as the adaptable algorithm library of signal processing and open API software modules. Through the integrated test of the SDR platform, the operational performance was verified in real-time. Also, through the field-application test, the ground target and air-vehicle drone target were successfully detected and their test results were presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.783-789
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• 2002

In this paper, V-band MMIC coupled oscillator arrays are presented. In the proposed array, two push-pull patch antennas are synchronized by using strong electromagnetic coupling between two antennas. As a result, total size of the array is reduced and the array can be integrated in a single chip. To verify proposed array concept, two 1$\times$2 arrays are designed and fabricated using standard 0.15 um gate length pHEMT MMIC process. The circuits are mounted in an oversized waveguide and measured. The first array shows 0.5 dBm at 56.372 GHz and the second one has an output of 5.85 dBm at 60.147 GHz.

• ETRI Journal
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• v.41 no.3
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• pp.337-347
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• 2019

The specific anthropomorphic mannequin (SAM) phantom was designed to provide a conservative estimation of the actual peak spatial specific absorption rate (SAR) of the electromagnetic field radiated from mobile phones. However, most researches on the SAM phantom have been based on early phone models. Therefore, we numerically analyze the SAM phantom to determine whether it is sufficiently conservative for various types of mobile phone models. The peak spatial 1- and 10-g averaged SAR values of the SAM phantom are numerically compared with those of four anatomical head models at different ages for 12 different mobile phone models (a total of 240 different configurations of mobile phones, head models, frequencies, positions, and sides of the head). The results demonstrate that the SAM phantom provides a conservative estimation of the SAR for only mobile phones with an antenna on top of the phone body and does not ensure such estimation for other types of phones, including those equipped with integrated antennas in the microphone position, which currently occupy the largest market share.

• ETRI Journal
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• v.46 no.2
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• pp.323-332
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• 2024

Receiver and transmitter monolithic microwave integrated circuit (MMIC) multifunction chips (MFCs) for active phased-array antennas for Ka-band satellite communication (SATCOM) terminals have been designed and fabricated using a 0.15-㎛ GaAs pseudomorphic high-electron mobility transistor (pHEMT) process. The MFCs consist of four-channel radio frequency (RF) paths and a 4:1 combiner. Each channel provides several functions such as signal amplification, 6-bit phase shifting, and 5-bit attenuation with a 44-bit serial-to-parallel converter (SPC). RF pads are implemented on the bottom side of the chip to remove the parasitic inductance induced by wire bonding. The area of the fabricated chips is 5.2 mm × 4.2 mm. The receiver chip exhibits a gain of 18 dB and a noise figure of 2.0 dB over a frequency range from 17 GHz to 21 GHz with a low direct current (DC) power of 0.36 W. The transmitter chip provides a gain of 20 dB and a 1-dB gain compression point (P1dB) of 18.4 dBm over a frequency range from 28 GHz to 31 GHz with a low DC power of 0.85 W. The P1dB can be increased to 20.6 dBm at a higher bias of +4.5 V.