• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.975-976
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• 2006

The passive type RFID (Radio Frequency Identification) System using Surface Acoustic Wave (SAW) tag at 900 MHz in the range of more than 1 m was fabricated. To improve interrogation range of the system propose a method to increase isolation between transmitter and receiver. This method using a direct conversion architecture achieves a leakage rejection of 10 dB increased compared with conventional system. Measured interrogation range is more than 1 m.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.336-341
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• 2014

Dosimetry of radiating electromagnetic wave from mobile devices to human body has been evaluated by measuring Specific Absorption Rate (SAR). Usual SAR measurement system scans the volume by robot arm to evaluate RF power absorption to human body from wireless devices. It is possible to fast estimate the volume SAR by software deleting robot moving time with the 2D surface SAR data acquired by arrayed probes. This paper shows the principle of fast SAR measurement and the measured data comparison between the fast SAR system and the robot scanning system. Data of the fast SAR is well corresponding with data of robot scanning SAR within ${\pm}3$ dB, and its dynamic range covers from 10 mW/kg to 30 W/kg with 4.8 mm probe diameter.

• ETRI Journal
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• v.28 no.3
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• pp.393-396
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• 2006

This letter proposes a new impedance matching scheme of a traveling wave electro-absorption modulator (TWEAM) module for a 60 GHz band radio-over-fiber (ROF) link. A microstrip band pass filter (BPF) was used to achieve impedance matching at the 60 GHz band, and termination resistance was carefully designed to obtain an input impedance close to $50\;{\Omega}$. Also, a bias circuit for the device was designed in the module. The measured return loss and frequency response show that the modulator module observes the characteristics of a filter without the need of a further tuning process.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2286-2291
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• 2008

Some electronics component, which is adopted as components of antenna for radar or satellite system and used for amplifying signals to transmit, is accompanied by very significant heat dissipation levels because of the inefficiencies inherent in radio frequency wave generation. So, proper cooling performance for that system is base requirement for thermal design. On this paper, we applied heat spreading structures to reduce thermal density and find the optimum values of heat sink design factors through theoretically, numerically and evaluated by product test. As the results, the performance of the cooling system shows the propriety of cooling high density heat dissipation electronics components.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.798-806
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• 2001

As electronic industry and radio communication technologies progress, the electrical and electronic equipments are lightened, minimized, and operated by low power. At the same time, these equipments react sensitively by electromagnetic wave noise. It is a origine these equipments to wrong-operation. In this paper, we focused on the design and preperation condition of a advanced EMI filter. This filter sowed superior attenuation effect of 10 dB~20 dB compare with typical filter in the range of frequency from 150 kHz to 30 GHz and superior character over the variation of a load.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.556-560
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• 2019

To provide high shunt impendence with low power losses, an 81.25 MHz continuous wave (CW) radio frequency quadrupole (RFQ) accelerator has been designed and machined as parts of the Low Energy Accelerator Facility (LEAF). In this paper, the mechanical structure and the main processing technology of the RFQ cavities are described according to the physical and geometric parameters requirements of the RFQ. The fabrication of the RFQ has been completed and the test results agree well with the design requirements. The RFQ accelerator will work in Institute of Modern Physics, Chinese Academy of Sciences in 2018.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.8 s.99
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• pp.803-809
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• 2005

This paper presents a novel method of mutual coupling suppression between antenna elements for performance improvement in planar array antenna system. Two miniature patch antenna elements satisfied IEEE 802.1 la($5.75\~5.35\;GHz,\;5.75\~5.85\;GHz$) are used for this research, they are arrayed by half wave length interval. It is observed about -20 dB mutual coupling between each antenna element at center frequency. To suppress mutual coupling, the arrayed antennas with a reversed 'U' structure are observed below -30 dB mutual coupling at IEEE 802.1la band.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.2
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• pp.128-136
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• 2001

This paper evaluates the performance of an optic link in a frequency conversion based fiber-radio system. The proposed link structure simplifies a BS(base station) via making the MMW(millimeter wave) optical pilot tone generated in the CS(control station) be used in the uplink as well as in the downlink. To acquire the optical pilot tone, an EOM(electro-optic modulator) in the CS is biased in three different ways, i.e., MAB(maximum bias), MIB(minimum bias), QB(quadrature bias). We, depending on the biasing of the EOM, evaluate the link performances in two cases; one is for constant laser source power and the other for constant received DC optical power at a PD(photo detector). Based on the simulation results on the downlink CNR and the uplink SFDR(spurious free dynamic range), we finally deduce the effective EOM biasing for each case.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1023-1029
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• 2007

In this paper, we propose the method to solve the BLT equations using Laguerre polynomials in time domain. The solution of BLT equations is obtained by recursive, differential and integral properties of Laguerre polynomials. The verification of the proposed method is tested by applying it to the two-wired transmission line with resistors and capacitors, which is illuminated by the electromagnetic plane wave pulse. And the result is compared with the corresponding transient responses obtained from inverse fast Fourier transform(IFFT) of the frequency domain solutions of BLT equations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.220-227
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• 2011

With the rapid development of mobile communication technology, the technologies based on the diverse digital modulation schemes have been used for the frequency range of over 800 MHz. The only radiation immunity has been tested using only AM signal based on IEC 61000-4-3 without any consideration of the influence of electromagnetic radiation in Korea. However, it has not been tested by wideband digital modulation signals such as cdmaone(IS-95), WCDMA and PM signal. The purpose of this study was to review the standards. In addition, the input signals were analyzed and tested considering the environments in Korea. The results showed that the devices were influenced by digital modulation signal or PM signal more than by AM signal.