• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.166-171
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• 2005

In this paper, a set of new complementary quadriphase sequences based on Jacket matrix is proposed. It is with a good zero cross correlation zone and efficiently eliminates the inter-user interferences for CDMA systems. Unlike the conventional complementary sequence designs, the proposed sequences can be easily extended to large odd and even sizes by using a fast linear transform for multi-user communication systems. The computer simulation shows that the proposed sequences have better performance than conventional multi-user spreading CDMA systems using ZCZ sequence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.32-40
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• 2008

Recently, due to the onset of the information age, various high-priced, large-size machines have been invented such as intelligent building and high-tech computer operated facilities. Consequently, all kinds of electrical, electronic, and communication equipments and facilities have been found to be vulnerable even to small amounts of electrical shock. Interference between equipments and equipment malfunction occur because of various electromagnetic interferences. Galvanic action by direct current (D.C.) causes gas valve corrosion and other electrical problems such as static electricity and electromagnetic interference (EMI) occur as well. Most of the problems stated above occur because of problems in grounding.

• Journal of electromagnetic engineering and science
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• v.1 no.2
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• pp.131-138
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• 2001

The DTV (Digital TV) tuner for an 8-VSB (Vestigial Side-Band) modulation was developed to meet the requirements of the ATSC (Advanced Television Systems Committee). The double frequency conversion and the active tracking filter in the front-end were used to cancel interferences between adjacent channels and multi-channels by suppressing the IF beat and the Image frequency. However, It was impossible to get frequency mapping between the tracking filter and the first VCO (Voltage Controlled Oscillator) in the existing DTV tuner structure which differs from the NTSC (National Television Systems Committee) tuner. This paper, therefore, suggests an assailable structure and a new method for the automatic frequency selection by mapping the frequency characteristics over the tracking voltage and the combined HW which is composed of a Micro-controller, an EEPROM (Electrically Erasable Programmable Read Only Memory), a DAC (Digital-to-Analog Converter), an OP amplifier, and a switch driver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.958-963
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• 2013

Ceramic dielectric waveguide duplexer was developed. Duplexer was designed in order to minimize the muture interferences between transmission port and receive port of bandpass filter. The design method for antenna port was determined by the transmission loss and calibrated the length of resonator of recriving filter. We used the ceramic powder of dielectric constant 9.46 and installed SMD type on PCB board.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.208-213
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• 2008

In recent society, the quality of human life has improved due to the use of electric appliances and the high powered electrical equipments. However, lots of electric appliances and equipments generate the electromagnetic field hazard. Many studies have been made about the wrong behavior of machines due to electromagnetic fields, the interferences in communication equipments, the possibility of the electromagnetic field hazard in human body, etc. There exist international standards about the RF equipments (ex. mobile phone, antenna, etc.). But, many researchers involved in power frequency electric and magnetic field only propose the prudential avoidance. In this paper, induced currents in a human body model due to magnetic fields in high speed railway are calculated by two dimensional impedance method. Power frequency(60Hz) magnetic fields are calculated and induced currents are simulated by Faraday's law. Induced currents are simulated with induced voltage, human body model impedances due to Ohm's law, magnetic fields derived from Biot-Savart's law and Transmission Line Method in high speed railway.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.18-23
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• 2022

This paper examines the electromagnetic shielding structure of ultra-high frequency (UHF) RF modules used in aircraft. Advances in electrical and electronic technologies have increased the need for electronic equipment in aircraft. High-frequency wireless devices have become integrated circuits in the form of UHF integrated circuits to support a wide range of frequencies and miniaturisation. To ensure the functionality and performance of these integrated devices in aviation, shielding is necessary to prevent unexpected electromagnetic interference, which could be detrimental to aircraft safety. A shield structure was designed to protect the RF chipset from malfunctioning, and the shielding effectiveness was improved through the application of various geometric shapes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.317-329
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• 1998

In this paper, we have analyzed the packet error probability of DS/CDMA-Trellis Coded QPSK modulation signal with MRC(Maximum Ratio Combining) diversity reception in Rician fading, multi-user interferences and multipath channel. And then we have evaluated the performance and capacity of DS/CDMA-Trellis Coded QPSK system using the MRC diversity reception as a function of direct power to indirect power ratio ($K_R$), the number of diversity branch(M), the number of multi-user(U), PN chip rate(PN), the number of multipath channel($L_P$), and packet length(PL). From the results, we know that the coding gain of DS/CDMA-Trellis Coded QPSK system with 2 branch MRC diversity is about 6 dB against uncoded DS/CDMA BPSK system with 2 branch MRC diversity in Rician fading ($K_R=6dB), 5 multi-user interferences, and 3 multipath channel. And, we know that coded QPSK signal designed for the AWGN channel also perform well on a Rician fading channel with MRC diversity reception. Consequently, we expected that proposed system structure is reliable to the wireless data communication system in Rician fading, multi-user interferences, and multipath channel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.3
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• pp.392-400
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• 1999

In this paper, the electromagnetic immunity of electronic medical equipments was tested by employing a standard test method for medical equipments. In addition, the electromagnetic interference to the medical equipments caused by four different types of mobile phones such as portable transceiver, analog, digital, and PCS cellular phones, have been studied. In this study, 16 medical equipments of 11 different types were investigated. There are a patient monitor, an infusion pump, a neonatal incubator and so on. In the case of the EMS test, the interferences were detected for seven medical equipments of four different types(53.3%) such as the patient monitor. For the two portable transceivers, 12 medical equipments of eight different models (75%) were affected. All medical equipments were satisfied with electromagnetic immunity by analog, digital and PCS cellular phones. The experiment results show that the malfunction of the electronic medical equipments is dependent on the frequency range and the electric field strength of the mobile phones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.284-290
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• 2016

As the recently advanced scientific developments result in high lever of the usability and the needs for the electrical equipment and devices in various situations, the safety technologies protecting malfunction and electrical critical damages including soft and hardware from the unexpectedly radiated electromagnetic interferences are required gradually. In addition, the numerical analysis for the miniaturized electrical components and equipments as well as the conventional electrical devices installed inside the electrically large enclosures and structures requires the memory requirement and time consumption too big to be handled in a realistic situation, which will result in a limitation in solving the complete set of maxwell's equations. In this paper, PWB method based on statistical theory and topological modeling with appropriate zoning concepts are introduced for the EM analysis of an electrically large complex structures.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.331-341
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• 2002

It is expected that the SCM (Subcarrier Multiplexing) optical link system, in which a number of small scale base stations with only antenna and RF transceiver are connected to central station through optical fiber, is in demand. In order to analyze the performance of SCM optical link system fur RF signal transmission, MZ(Mach-Zehnder) modulator's transfer function is modelled as nonlinear form with the cube of input signal. And considering the multiple access interferences occurred In the demodulation of other users'CDMA signals with multipath components after passing through MZ modulator, the BER performance is analyzed.