• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1276-1282
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• 2003

The SMT(Surface Mount Type) ferrite bead used to reduce the influx of power bus noise is modeled with parallel capacitor(C), series resistor(R) and series inductor(L). The simple equivalent circuit modeling doesn't agree with the measurement result. In this paper, we proposed the accurate equivalent circuit model of the ferrite bead at wide frequency range(50 MHz∼3 GHz) and analyzed the noise effect to the high speed IC(Integrate Circuit) with ferrite bead or not.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.848-853
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• 1993

The properties of ferrite bead, a low-pass filter, are determined by the frequency dispersion of the complex permeability. In this study, frequency dispersion of complex permeability of the Ni-Zn ferrites with different Ni/Zn ratio were investigated. Relationship between the behavior of filter and dispersion of complex permeability of a ferrite was studied. As a result, it was concluded that the compositions for Ni/Zn ratio of $0.41{\sim}0.47$, having high initial permeability and good sensitivity, were favorable as a ferrite bead filter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.535-541
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• 2013

The present study was carried out to investigate the effects of welding parameters such as current, voltage and shielding gases on the bead shape, microstructures and hardness. It was confirmed that bead height was lowered and bead depth was increased with increasing voltages while height, depth and width of beads increased with welding currents. The hardness of weld metals with Ar+10% $O_2$ and Ar+20% $CO_2$ was low due to the formation of grain boundary and polygonal ferrites while that of weld metals with Ar+2% $O_2$ was high due to the presence of acicular, bainitic and sideplate ferrites.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.525-528
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• 2002

The proposed EMC filter composed with feed-through capacitors and ferrite beads of high permeability was prepared which satisfy the EMC standard for a wide-band noise signal in the frequence of 10 MHz to 1.5 GHz in power supply line. The optimum structure of ferrite bead was found by calculating the load effect of ferrite beads. As a result, the filter showed excellent differential- and common-mode noises filtering characteristics above 30dB 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 1.8GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.376-383
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• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each subsystem, this partition will cause unwanted effects. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is used for the way of maintaining radiated emission, still specific user's guide doesn't give sufficient principle. In a view point of EMI, design principle of multi-CB using method will be analyzed by measurement. And design principle of noise mitigation will be provided. Generally interval of multi-CB is ${\lambda}/20$ ferrite bead. In this study, When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of EMI.

• Journal of Welding and Joining
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• v.11 no.4
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• pp.57-69
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• 1993

In the present study, the microstructure and Charpy V notch toughness of multipass $CO_2$ FCA weldment in three different heat inputs(1-3KJ/mm)were investigated. The weldments using two different domestic FCAW wires(AWS E71T-1 and E71T-5 equivalent) in C-Mn steel were chemically analysed. The following conclusions can be inferred. 1. T-1 wire Showed a stable arc transfer, less spatter and harsh, a better bead spreading and easy slag removal, whereas T-5 wire suffered from the arc stability, which tended to increase spatter and produce a more convex bead. 2.The microsturctures of the top beads of the weldments in three different heat inputs consisted of coarse-grained boundary ferrite and Widmanstatten ferrite side plate with increasing heat inputs. The modest fraction of acicular ferrite in the two wire weldments was observed in the 2KJ/mm heat input. 3.The fine-grained reheated zones of both welds consisted of a duplex microstructure of polygonal ferrite and second phases. 4. The basic flux weldment of T-5wires showed a higher Charpy impact property than that of T-1 wires because of a higher fraction of acicular ferrite in the weld microstructure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.11-15
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• 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 became 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 Navigation and Port Research
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• v.28 no.8
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• pp.715-719
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• 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 Navigation and Port Research
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• v.34 no.1
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• pp.33-37
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• 2010

It is very important to prevent the electromagnetic interference and to prevent malfunction of electronic equipments mounted on ships. To solve these problems, in this paper, the EMC filter was designed, fabricated, and tested. The Ni-Zn ferrite beads with high permeability were used to make large inductance as the inductor and the feed-through capacitors without any resonance points. As a result, excellent attenuation characteristics of 25~70 dB were obtained from the 0 kHz~1.5 GHz band. In addition, when the Electric Fast Transient (EFT) of 4 kV in the level 4 of IEC 61000-4-4 was induced the EFT reduced to 600 V. Therefore, it was clearly shown that the developed EMC felter can be used for suppressing the electromagnetic interference on-board electronic devices and equipments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.183-184
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• 2009

In this paper the internal or external of the ships mounted electronic devices due to the propagation of electromagnetic interference and to prevent malfunction EMC filter was designed and fabricated. It was designed and fabricated with Ni-Zn ferrite beads of high permeability to make large inductance as the inductor and Feed-through capacitors, which did not have any resonance point, to restraint resonance effectively, and the characteristics was evaluated. The results from the 0 kHz$\sim$1.5 GHz bandwidth of $25{\sim}70$ dB were able to obtain excellent attenuation characteristics. And, when the Electric Fast Transient (EFT) of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon attenuated more than 1/6 to 600 V. Therefore, it was confirmed that the developed EMC filter can be used for suppressing ships mounted electromagnetic interference between electronic devices.