• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
• /
• pp.22-22
• /
• 2000

The discoveries of high temperature superconductors received great attention due to their high critical temperatures. These materials also exhibit extremely high critical magnetic fields and high critical current density at low temperature, high magnetic field. Thus, they are the most promising materials for superconducting magnets above 20 T. In this talk, progress in the development of HTS materials and insert coils at the National High Magnetic Field Laboratory will be reviewed. In 1999, a Bi-2212 stack of double pancakes generated 3 T in a 19 T background field. These results will be reviewed in terms of implications for future systems. Individual double pancakes of Bi-2223 have also been tested and their performance will also be discused. The present goal of a 57 system will be presented and the key technical requirements for larger, higher field systems will be addressed. It will be shown that in addition to increased critical current density, improved mechanical performance (stain resistanced) is necessary for high field systems. Furthemore, improvements in the conductor n-value will improve prospects for operational systems.

• 천문학회지
• /
• 제8권1호
• /
• pp.29-34
• /
• 1975

Solar electrical conductivity has been calculated, making use of Yun and Wyller's formulation. The computed results arc presented in a tabulated form as functions of temperature and pressure for given magnetic field strengths. The results of the calculation show that the magnetic field does not play any important role in characterizing the electrical conductivity of the ionized gas when the gas pressure is relatively high (e.g., $P{\geq}10^4\;dynes/cm^2$). However, when the gas pressure is low (e.g., $P{\leq}10\;dynes/cm^2$), the magnetic field becomes very effective even if its field strength is quite small (e.g., $B{\leq}0.01$ gauss). It is also found that, except for lower temperature region (e.g., $T{\leq}10^{4^{\circ}}K$), there is a certain linear relationship in a log- log graph between the pressure and the critical magnetic field strength, which is defined as a field strength capable of reducing the non-magnetic component of the electrical conductivity by 20%.

• 한국대기환경학회지
• /
• 제12권3호
• /
• pp.243-254
• /
• 1996

The main purpose of this study is to investigate the collection efficiency characteristics of a cylindrical ESP. To do that, it is necessary to analyze the electric field, gas flow field, and mechanism of particle movement by numerical simulation based on EHD model. For a gas flow field, Navier-Stokes equation involving the electric source term was solved by SIMPLE algorithm. In case of the electric field, the current continuity and electric field equations were solved by S.O.R. method. The analysis of particle movement was performed on the basis of PSI-CELL model from the Lagrangian viewpoint. The results showed that the influence on the gas flow field by the electric field is almost negligible in a cylindrical ESP. The particle drift velocity $V_P$ toward the collection surface is increased continuously by the electrostatic force due to the rise of particle charge as the particle is moving to the flow direction and the particle size becomes larger. The collection efficiency is to quitely higher with the increase of applied voltage for the same particle size, while becomes smaller as the inlet velocity is increased.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.478-479
• /
• 2008

this paper describes the electric field distribution interpretation along a shield form inner vacuum interrupter(VI). The equipotential line and electric field and field vector in a VI are analysed by a finite element method at various shield form. in result, The equipotential line and electric field distribution was affected to VI shield form. The reason is as it gets distortion of equipotential line done. shield of cup type is how to electric field distribution, finally, this paper recognized whether or not affected, and proposed gap with the most suitable shield length and an external insulation.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제52권7호
• /
• pp.305-309
• /
• 2003

This paper was shown the simulation of electric field distribution of globular dielectric for design of ideal packed-bed plasma reactor. When discharge gap between the electrodes and input voltage are each 20[mm]. 10000[V] in the atmosphere, the results of simulation to the electric field was measured stronger at globular dielectric of $\phi$5[mm] than 1$\phi$[mm] and 3.33$\phi$[mm]. And the maximum electric field or globular dielectric with $\phi$10[mm] was increased about 5[%] to maximum electric field of globular dielectric with $\phi$5[mm] in the atmosphere. when dielectric constant of globular dielectric is 100, it was simulated about 90[%] of maximum electric field of globular dielectric over 1000 dielectric constant. Ana the highest electric field appeared as globular electric was parallel structure with the other globular dielectric side by side of the globular dielectric and connected to electrodes.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
• /
• pp.312-314
• /
• 2000

The electric wave propagation characteristics of electromagnetic field by induction current shows a nonlinear distinction in the metal but linear on air. This paper is written about the magnetic transmission distinction in the metalic tube, which wrapped the center axis by the same direction. The electromagnetic field made by the transmission signal is transferred from the transmission coil area toward the receiving coil by the magnetic diffusion. So, it is different magnetic flux around the coil with one in the remote field area. Analyzing such a complex magnetic characteristic, we verified this theory by the vector analysis and presented eddy current mechanism and analytical model about magnetic distribution in the remote field area. This magnetic distribution rate in metal body will be very useful in the nondestructive inspection of the eddy current in remote field which is recently rising as a new technology.

• 전기학회논문지
• /
• 제67권9호
• /
• pp.1165-1173
• /
• 2018

Recently, owing to environmental problems and instability of rare earth resources market, non-rare earth electric motors are attracting attention. As a non-rare earth motor type, a wound rotor synchronous motor(WRSM) has high power density and wide driving range further it can reduce loss by field current control during field weakening control at high speed. However, since the d-axis flux of the WRSM is coupled with the rotor circuit, the fluctuation in the d-axis flux linkage affects the rotor circuit, which causes ripple of the field current and torque. In this paper, we propose the field current ripple compensation method by injecting the feedforward voltage. the proposed compensating method was demonstrated by simulation and experiments.

• Geomechanics and Engineering
• /
• 제37권3호
• /
• pp.243-251
• /
• 2024

In the current work, a poro-thermoelastic half-space issue with temperature-dependent characteristics and an inclined load is examined in the framework of the three-phase-lag model (3PHL) while taking into account the effects of magnetic and gravity fields. The resulting coupled governing equations are non-dimensional and are solved by normal mode analysis. To investigate the impacts of the gravitational field, magnetic field, inclined load, and an empirical material constant, numerical findings are graphically displayed. MATLAB software is used for numerical calculations. Graphs are used to visualize and analyze the computational findings. It is found that the physical quantities are affected by the magnetic field, gravity field, the nonlocal parameter, the inclined load, and the empirical material constant.

• 한국자원식물학회지
• /
• 제35권5호
• /
• pp.675-685
• /
• 2022

2018년부터 2020년까지 화훼작물의 시설 및 노지재배지의 토양 화학성을 비교 분석하였다. 시설재배지 토양의 pH는 3년간 적정 범위 유지되었고, 노지토양도 적정 범위로 유지되었다. 유기물 함량은 두 토양에서 모두 적정 범위로 유지되었고, EC의 경우 시설토양은 적정 기준보다 높았으나, 노지토양에서는 적정 기준 범위로 유지되었다. 유효인산은 시설토양에서 2018년에 560 mg/kg가장 높았으나 매해 낮아져 2020년에 적정 기준 범위로 낮아졌고, 노지재배지 토양은 매해 적정 범위에 유지되었다. 치환성 양이온은 시설재배지 토양에서 3년간 표준 범위보다 높게 유지되어 영양 불균형이 극심하였고, 특히 치환성 칼슘과 마그네슘의 유의성이 높았다. 그러나 노지재배지 토양에서는 치환성 칼슘과 마그네슘이 적정 범위보다 약간 높은 수준이었다. 주성분 분석을 통해서 시설재배지 토양의 치환성 양이온을 비롯해 유효인산, EC가 높은 문제점이 드러났으며, 노지재배지는 시설재배지보다는 상대적으로 낮은 값의 유효인산, EC, 치환성 양이온 분포를 보였다. 그러나 노지재배지 토양의 pH는 변동성이 너무 크고 pH가 높은 토양의 비율이 시설재배지보다 높았다. 또한, 노지재배지 토양은 시설재배지보다 유기물 함량이 낮으므로 유기물 시용에 더욱 적극적으로 노력해야 할 것으로 판단되었다.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
• /
• pp.126-131
• /
• 2008

Fire-fighters have been struggling against heat and dense smoke caused by fire when it occurs especially at the basement or the inner place of a building. An indoor fire-fighting robot with well heat-resistance, great searching cameras and good extinguishing ability has been recently developed. It never suffocate, coming into the fire district and extinguishes fire directly. In this study, several experiment was conducted to promote field working ability of the fire-fighting robot. As a result, heat resistance, water discharge and field working appeared satisfactory.