• 한국전자파학회논문지
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• 제14권12호
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• pp.1276-1282
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• 2003

SMT 타입의 페라이트 비드(ferrite bead)는 전원단에서 발생되는 잡음(noise)이 회로 소자로 유입되는 것을 막기 위해 사용되는 소자로 병렬 캐패시터(capacitor)와 직렬 인덕터(inductor) 및 저항(resistor)을 이용하여 등가 모델화된다. 이와 같은 간단한 페라이트 비드의 등가 모델은 광대역 범위에서 측정 결과와 일치하지 않는다. 본 논문에서는 광대 역(50 MHz∼3 GHz)에서 정확한 페라이트 비드의 모델을 제시하고 페라이트 비드가 있을 때와 없을 때 전원단 잡음의 회로 소자에 미치는 영향을 고찰하였다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.315-318
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• 2001

We are proposing a new mobile phone antenna, which has a specially manufactured Mn-Zn cylindrical ferrite bead inside of the helical coil of the antenna. The extended antenna radiation patters and the spatial peak SAR averaged over 1 gram simulated tissue with and without the ferrite bead insertion were measured at 824 MHz. The results show that the ferrite bead resulted in SAR reduction about 20 %, and reflection coefficient increase about 7 % for the extended antenna. The applicability of this scheme to the antenna mass production is quite feasible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.97-100
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• 1996

In this paper, 3-terminal EMI filter for communication was studied. EMI filter for communication combining Ferrite bead with 3-terminal capacitor was constructed with T-type. We was able to control resonance frequency with chip capacitor value and attenuation characteristics by Ferrite bead properties.

• Journal of Welding and Joining
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• 제17권2호
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• pp.36-43
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• 1999

The effect of microstructure on the fracture toughness of multi pass weld metal has been investigated. The micromechanisms of fracture process are identified by in-situ scanning electron microscopy(SEM) fracture observation using single edge notched specimen. The notches of the in-situ fracture specimens were carefully located such that the ends of the notches were in the as-deposited top bead and the reheated weld metal respectively. The observation of in-situ fracture process for as-deposited top bead indicated that as strains are applied, microcracks are formed at the interfaces between soft proeutectoid ferrite and acicular ferrite under relatively low stress intensity factor. Then, the microcracks propagate easily along the proeutectoid ferrite phase, leading to final fracture. These findings suggest that proeutectoid ferrite plays an important role in reducing the toughness of the weld metal. On the other hand, reheated regions showed that the microcrack initiated at the notch tip grows along the localized shear bands under relatively high stress intensity factor, confirming that reheated area showing momogeneous and fine microstructure would be beneficial to the fracture resistance of weld metal.

• 한국통신학회논문지
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• 제18권6호
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• pp.848-853
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• 1993

저역 통과 필터인 페라이트 비드의 특성은 페라이트의 복소투자율의 주파수 분산거동에 의해서 결정된다. 본 실험에서는 Ni-Zn페라이트의 Ni-Zn페라이트의 Ni/Zn 비 변화에 따른 복소투자율에 주파수 분산거동을 조사하고 이것이 필터의 삽입감쇠 거동에 미치는 영향을 고찰하였다. 본 실험은 결과 초투자율이 비교적 크고 필터로서의 민감도도 우수한 Ni/Zn 비가 $0.41{\sim}0.47$인 조성이 페라이트 비드필터용으로 가장 적합함을 알 수 있었다.

• Journal of Welding and Joining
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• 제11권4호
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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.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1998년도 특별강연 및 춘계학술발표 개요집
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• pp.150-154
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• 1998

The purpose of this paper is to investigate optimum welding conditions of STS 304 thin sheet by GTA welding and control 6 $\delta$--fenite which is harmful in mechanical processing, corrosion problem and can be formed brittle a phase in using long term at high temperature. One series of automatic welds was made using argon plus 10, 20, 30 % nitrogen to ensure a fully austenite deposit. Results obtained were summarized as follows: 1) 6 $\sigma$ferrite content in the weld metals is influenced largely by the nitrogen content. 2) Additions of nitrogen to the shielding gas can significantly reduce the amount of retained delta ferrite and result in an increase in hot cracking. 3) Bead width was increased when Ar + $N_2$ shielding gas was used and travel speed was increased. 4) Ar+$N_2$ shielding gas made weld metal ductile and reduce 6 -$\delta$-ferrite.

• Journal of Welding and Joining
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• 제14권6호
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• pp.93-100
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• 1996

Effect of a flux composition on weld metal toughness in submerged arc welding with 60kgf/$\textrm{mm}^2$ grade C-Mo type wires was investigated and interpreted in terms of weld metal microstructure and hardenability. Flux workability was also studied by characterizing a weld bead profile. Compared to other weld metals, .weld metal used alumina basic flux with nickel showed lowest oxygen content, highest hardenability and the most acicular ferrite. The highest impact toughness of that weld metal, however, was attributed to the tough matrix due to the nickel rather than to the larger amount of acicular ferrite. Manganese silicate flux had better workability than alumina basic flux, showing broader welding conditions resulting in a depth-to-width ratio of 0.5. The composition of oxides in the weld metal was dependent on the flux composition, showing MnO-SiO$_2$-TiO in manganese silicate flux and MnO-SiO$_2$-Al$_2$O$_3$-TiO in alumina basic flux. MnO-SiO$_2$composition in both oxides was similar to a tephroite.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.589-592
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• 2001

In this paper, Electronic ballast for multiple fluorescent lamps based on the use of ferrite beads are presented. The use of this system in place of the conventional electromagnetic ballast results in lower power consumption and reduced maintenance cost, because the electronic system has higher efficiency and longer lamp lifetime than the electromagnetic ballast. In comparison with the conventional electronic ballast. The proposed system presents a significant reduction of cost. This reduction becomes were meaningful with the growing of the lamp number. The description of the lighting system, We show that the proposed model can be applied to multiple lamps electronic ballast by simulation processes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.589-592
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• 2001

In this paper, Electronic ballast for multiple fluorescent lamps based on the use of ferrite beads are presented. The use of this system in place of the conventional electromagnetic ballast results in lower power consumption and reduced maintenance cost, because the electronic system has higher efficiency and longer lamp lifetime than the electromagnetic ballast. In comparison with the conventional electronic ballast. The proposed system presents a significant reduction of cost. This reduction becomes were meaningful with the growing of the lamp number. The description of the lighting system, We show that the proposed model can be applied to multiple lamps electronic ballast by simulation processes.