• Journal of Navigation and Port Research
• /
• v.28 no.8
• /
• pp.715-719
• /
• 2004

This paper deals with EMC filter for a personal computer(PC). A PC contains many sources of noise inside and out, with many connected cables. High noise levels are also emitted from the PC because of high-speed signals. So radiated noise from the computer body may sometimes cause problems. Therefore, we design and fabricate an electromagnetic compatibility (EMC) filter for PC, which is composed of feed-through capacitors and ferrite beads with high permeability. Through extensive test, the proposed EMC filter is shown to have excellent differential-mode and common-mode noises filtering characteristics above 30 dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.12
• /
• pp.79-84
• /
• 2007

This paper presents an improved field uniformity in a reverberation chamber, that can be alternatively used for the analysis and the measurement of electromagnetic interference and immunity, with a designed CRD(Cubical Residue Diffuser) that have various dimensions. The Schroeder type CRD is designed for $1\sim3$ GHz band and the FDTD(Finite Difference Time Domain) method is used to analyze the field characteristics. At 2 GHz, the standard deviation of test volume in the reverberation chamber is the smallest and has a good field distribution with a CRD of $40\sim80%$ dimension of one side of the reverberation chamber. The Electric field uniformity gets worse when the dimension of a CRD is either below 40 % or above 80 % of the side wall. The result shows that the standard deviation of the test volume in the reverberation chamber with a CRD of 44 % dimension is improved by 1 dB compared with that of the reverberation chamber with a CRD of 100 % dimension.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.8
• /
• pp.121-127
• /
• 2008

This paper presents an electric field distribution in a reverberation chamber using cylindrical diffuser. The characteristics of electric field distributions are compared with QRD(Quadratic Residue Diffuser) and cylindrical diffuser for $1{\sim}3$ GHz frequency band. The FDTD(Finite-Difference Time-Domain) method is used to analyze the field characteristics, and the field uniformity. At 2 GHz, the standard deviation and the tolerance of test volume in the reverberation chamber are improved by 0.11 dB, 0.43 dB for the case of cylindrical diffuser. The field strength is increased by 43.2 dBmV/m vs QRD's of 36.6 dBmV/m. Comparing with QRD's, the characteristic of polarization is also improved. These results show that reverberation chamber using cylindrical diffuser can be used alternative facility for measurement of electromagnetic interference and immunity.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.3
• /
• pp.269-274
• /
• 2011

The purpose of hull stress monitoring system(HSMS) is to lead hull structure to be safer at lower cost. We proposed a hull stress monitoring system for leisure boats using fiber-optic bragg grating(FBG) strain sensor. Fiber optic sensors are well suited for structure monitoring system, due to their ability to withstand harsh environments, immunity to electromagnetic interference, and reduce cabling installation cost when employing wavelength multiplexing. This paper presents an overview of current research and design of hull stress monitoring system for leisure boats.

• Journal of Radiation Protection and Research
• /
• v.33 no.1
• /
• pp.1-12
• /
• 2008

International Standardization in all technical area is gaining its momentum as its impact and implication over global trade is directly linked. The worldwide competition to secure a dominant position in the standardization process is ever growing over the years. In 2005, the International Technical Committee on Nuclear Instrumentation, which is a subunit of International Electro-technical Commission (IEC), was held in Korea under the auspices of MOST (Ministry of Science and Technology). Korea has adopted its Rule and Regulation as the National Standard. As a part of a link to National Mid-and Long-term Atomic Energy R&D Program of MOST, the technical development of a performance test for the radiation monitors was carried out under mechanical environment and electromagnetic immunity conditions. The characteristics of the radiation fields were also evaluated under the conditions and introduced to a techniques of performance test for the radiation protection instrumentation adopted IEC61526 standards and it's results was analyzed. We would like to share the experience gained in these efforts, failure as well as success, and to discuss the problems encountered and serious consideration to be taken into account in the future endeavor.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.5
• /
• pp.879-886
• /
• 2008

This paper addresses the analysis and the design optimization of differential interconnects for Low-Voltage Differential Signaling (LVDS) applications. Thanks to the differential transmission and the low voltage swing, LVDS offers high data rates and improved noise immunity with significantly reduced power consumption in data communications, high-resolution display, and flat panel display. We present an improved model and new equations to reduce impedance mismatch and signal degradation in cascaded interconnects using optimization of interconnect design parameters such as trace width, trace height and trace space in differential flexible printed circuit board (FPCB) transmission lines. We have carried out frequency-domain full-wave electromagnetic simulations, time-domain transient simulations, and S-parameter simulations to evaluate the high-frequency characteristics of the differential FPCB interconnects. The 10% change in trace width produced change of approximately 6% and 5.6% in differential impedance for trace thickness of $17.5{\mu}m$ and $35{\mu}m$, respectively. The change in the trace space showed a little change. We believe that the proposed approach is very helpful to optimize high-speed differential FPCB interconnects for LVDS applications.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.5
• /
• pp.13-25
• /
• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.