• 전기학회논문지
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• 제63권6호
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• pp.770-775
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• 2014

According to ICNIRP guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields up to 300GHz, magnetic flux density which range from 3Hz to 150kHz are regulated to lower than $6.25{\mu}T$. In order to comply with its standard, OLEV(On-Line Electric Vehicle) have been designed considering EMF(Electro-Magnetic Field) reduction. However, if a current flowing in power line would be bigger for increasing power transfer efficiency, the established shield system no longer acts their role properly. In this paper, therefore, FCCL(Flexible Copper Clad Laminate) is applied to power line and pick-up devices to solve the problems. Though, the FCCL is normally utilized to insulator on circuit board, because of its high heat resistance characteristic, flexibility and thin properties, it makes effectiveness in the shielding device as well. 4 types of FCCL shielding structure are introduced to power line and pick-up devices. From the results, the FCCL which are placed in proposed positions shows maximum EMF reduction compared to the established shielding structure. Henceforth, if OLEV is applied FCCL shielding structure in practice, it will not only be more safe but also step forward to commercialization near future.

• 전기학회논문지
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• 제68권1호
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• pp.207-214
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• 2019

A large-capacity wireless power system is a technology that transmits electric power of kW or more in a noncontact type. Electric cars, electric buses, and electric railways. In order to increase the power transmission efficiency, a resonance method using a frequency of kHz is applied and the efficiency is 80 ~ 90%. In this case, the loss is 10 ~ 20% other than efficiency, and corresponds to several hundreds of W to several kW in kW class wireless power transmission. 35 kW wireless feed system environment, and induced current in the nearby conductive part was measured. As a result of analysis, it was confirmed that induction phenomenon is higher as the loop configuration of the conductive part per area is dense. The increase of the induced current in the mesh loop is characterized by the density of the nearby conductive part having a permeability per unit area. The concentration of the magnetic field by the permeability is increased and the induction phenomenon causing the induction current is increased. It was confirmed that induction phenomenon increases by about 2.7 times when 9 times dense structure is formed.

• 한국전기전자재료학회논문지
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• 제30권10호
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• pp.646-650
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• 2017

We have evaluated the ferroelectric and electrical properties of pure $BiFeO_3$ (BFO) and $Bi_{0.9}A_{0.1}Fe_{0.975}V_{0.025}O_{3+{\alpha}}$ (A=Nd, Tb) thin films on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by using a chemical solution deposition method. The remnant polarization ($2P_r$) of the $Bi_{0.9}Tb_{0.1}Fe_{0.975}V_{0.025}O_{3+{\alpha}}$ (BTFVO) thin film was approximately $65{\mu}C/cm^2$, with a maximum applied electric field of 950 kV/cm and a frequency of 10 kHz, where as that of the $Bi_{0.9}Nd_{0.1}Fe_{0.975}V_{0.025}O_{3+{\alpha}}$ (BNFVO) thin film was approximately $37{\mu}C/cm^2$ with a maximum applied electric field of 910 kV/cm. The leakage current density of the co-doped BNFVO thin film was four orders of magnitude lower than that of the pure BFO thin film, at $2.75{\times}10^{-7}A/cm^2$ with an applied electric field of 100 kV/cm. The grain size and uniformity of the co-doped BNFVO and BTFVO thin films were improved, in comparison to the pure BFO thin film, through structural modificationsdue to the co-doping with Nd and Tb.

• 전기학회논문지
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• 제66권12호
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• pp.1844-1851
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• 2017

As the capacity of the wireless power transmission increases, a higher supply current which may induce current in nearby conductive parts requires. Induced current may affect electric shock to the human body and malfunction of the electrical equipment. In order to prevent such induced phenomena as a risk factor, shielding is required between the source of the wireless power transmission and the conductive parts. The resonance frequency for the large capacity wireless power transmission has the wavelength of several hundred meters, so most environments are included in the near-field area. By wave impedance, the electric field has higher density in the near-field area and needs to be analyze for protecting. For this purpose, it is necessary to select a substance having a larger electric conductivity and optimized shielding structure. In this paper, an aluminum base shielding structure was presented to conduct experiments on thickness, position, and heat dissipation. In the 35 kW, 60 kHz environments, the optimized 5T Al base shielding structure attenuates the induced current to 43 %.

• 한국정밀공학회지
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• 제26권3호
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• pp.122-128
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• 2009

DBD(Dielectric Barrier Discharges) plasma is often used to clean the surface of semiconductor. The cleaning performance is affected mainly by plasma density and duration time. In this study, the plasma density is predicted by coupled simulation of flow, chemistry mixing and reaction, plasma, and electric field. 13.56 MHz of RF source is used to generate plasma. The effect of dielectric thickness, gap distance, and flow velocity on plasma density is investigated. It is shown that the plasma density increases as the dielectric thickness decreases and the gap distance increases.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.257-261
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• 2000

The value of I$_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on B${\bot}$(vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the B${\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape according to the iron plate to obtain small B${\bot}$ by using Biot-Savart's law, image method and 2D FEA(2 Dimensional Finite Element Analysis) considering the stress condition of HTS. Moreover, the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEA, in which flux density at armature is calculated in 5kVA class HTSG.

• 한국재료학회지
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• 제17권3호
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• pp.173-178
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• 2007

Carbon nanotube cathodes(CNT cathodes) with a trench structure similar to gated structure of triode-type cathode were fabricated by a screen printing method using multi-walled carbon nanotubes. The effects of surface treatments on CNT cathodes were investigated for high efficiency field emission displays(FEDs). A liquid method easily removed the organic residue and protruded the CNTs. Field emission properties were measured by using a diode-type mode. The liquid method produced a turn-on field of $1.4V/{\mu}m$. The emission current density was measured about $3.1mA/cm^{2}$ at the electric field of $3V/{\mu}m$. The liquid method showed a high potential applicable to the surface treatment for triode-type FEDs.

• 한국표면공학회지
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• 제32권3호
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• pp.385-388
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• 1999

Electron field emission properties from various CVD diamond films were studied. Diamond films were synthesized by microwave plasma CVD at 1173K and at 673K substrates temperature and pulse microwave plasma CVD at 1173K. B-doped diamond film was synthesized by microwave plasma CVD at 1173K also. Estimation by SEM, both the non-doped diamond film and B-doped diamond film which were synthesized at 1173K substrate temperature were $2~3\mu\textrm{m}$ in diameter and nucleation densities were $10^{8}{\;}numbers/\textrm{cm}^2$ order. The diamond film synthesized at 673K was $0.2\mu\textrm{m}$ in diameter and nucleation densities was 109 numbers/cm2 order. The diamond film synthesized by pulse microwave plasma CVD at 1173K was $0.2\mu\textrm{m}$ in diameter and nucleation density was $10^{9}{\;}numbers/\textrm{cm}^2$ order either. From the result of electron field emission measurement, electron field emission at $20V/\mu\textrm{m}$ from CVD diamond film synthesized by pulse microwave plasma CVD was $37.3\mu\textrm{A}/\textrm{cm}^2$ and the diamond film showed the best field emission property comparison with other CVD diamond.

• 한국전자통신학회논문지
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• 제7권4호
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• pp.833-837
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• 2012

SC1(Standard Cleaning) 시간을 줄여 STI 측벽에서의 실리콘 손실 및 과도절개를 최소화하여 DRAM에서의 데이터 유지시간을 증가시키는 방법을 제안한다. SC1 시간 최적화를 통해 STI 상층 모서리부에서의 기생 전기장을 약화시킴으로서 Inverse Narrow Width 효과를 감소시키면 셀 트랜지스터의 Subthreshold 누설의 증가없이 채널 도핑농도가 감소하게 된다. 이것은 셀 접합에서 P-Well간 공핍 영역에서의 전기장을 최소화하여 일드나 데이터 유지시간의 증가를 보여 주었다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.23.4-23.4
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• 2008

In March and April 2001, the apogee (~9 Re) of the Polar spacecraft was located near the subsolar magnetopause with its orbital plane nearly parallel to a magnetic meridian plane. Polar electric and magnetic field data acquired during the two-month interval of solar maximum have been used to study fundamental standing Alfven waves near the subsolar meridian plane (magnetic local time = 1000-1400 hours) at magnetic latitudes from the equator to $\pm45$ degrees and at L values between 7 and 12. In the frequency band from 1.5 to 10 mHz, fundamental mode oscillations were identified based on high coherence (more than 0.7) and an approximately 90-degree phase shift between the azimuthal magnetic and radial electric field components. The L dependence of the fundamental frequencies is studied, and the frequencies are compared with those observed near the solar minimum interval (Takahashi et al. 2001). We found that the average frequencies in solar maximum are lower than those in solar minimum by a factor of ~2. This implies that the mass density in solar maximum is higher than that in solar minimum by a factor of ~4. Since there is a positive correlation between solar irradiance and solar activity, we suggest that the ionosphere in solar maximum produces more ions and load magnetic flux tubes with more ions.