• Journal of Welding and Joining
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• v.32 no.5
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• pp.32-43
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• 2014

Welding and joining technology has become a core field. Therefore it is more widely applied to nonferrous metals, inorganic and polymeric materials. That is because the high performance, high function and diversification trend of materials used as industrial technology develops. In the laser welding process, STS 304 and SCP1-S were used as the base materials, the output density was fixed $7MW/cm^2$, the protective gas was argon(Ar) and the transfer rate was fixed 5 mm/sec. and it was progressed while the magnetic field is gradually increasing by 100 mT ranging 0 to 400 mT. The tensile test showed in average about 6 % tensile strength improvement in the case of the laser welding process using the magnetic fields. In the shielded metal arc welding process using SPHC only or the combination of SPHC+STS304 as base materials. The electric current was set at 80 Amperes and the protective gas used argon(Ar) the same as the laser welding process and the strength of magnetic fields. In the shielded metal arc welding process using the magnetic fields, the tensile tests showed about 5 % tensile strength improvement in the case of using SPHC only, 3 % tensile strength improvement in the case of using the combination of SPHC+ STS304. In comparing the results of numerical analysis to the results of experimental tests, it was revealed that the temperature, thermal stress distribution and the behavior of molten pool were similar to those of real tests. Consequently, it may be considered that the numerical assumption and the analytical model used in this study were reasonable.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.110-119
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• 2009

In this study magnetic fields near electric power lines with branch lines which have a arbitrary angle were derived and formulated by dipole antenna theory and could be calculated easily using the formula. It seems that those formula could be applicable to the consideration of magnetic fields during the design of distribution lines with branch lines. As an example those formulated equations on elements of magnetic fields were applied to a model of 3 phase distribution lines with branch lines and calculated by Matlab programs and the results were presented The analyzed results are follows. The resultant magnetic field is dominated by the componant By all over y-axis in the case of the smaller branched angle $\alpha$ and the lower observed point z. In case of ${\alpha}=\frac{\pi}{2}$[rad], the resultant field is affected by the componant Bx. The resultant field is dominated by the componant Bz at the vicinity of the power lines and it shows very large value at the branch line position of y-axis in case of ${\alpha}>\frac{\pi}{2}$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.3
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• pp.51-58
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• 1998

This paper deals with the power frequency electric and magnetic profiles from transformer and gas-insulated swichgear(GIS) perimeters in the indoor power substation. Measurements of electric and magnetic field magnitudes were carried out by using single axis and three axes field meters at a height of 1[m]. The resultant electric and magnetic field profiles measured in the vicinity of the transformer were displayed as a 2-dimensional plot. The electric fields intensity are relatively low value of about 2.3~9[V/m], and the magnetic fields intensity range from 0.3 to [$20.3\mu$T]. Also, in the GIS perimeter the electric fields intensity are in the range of 2.2~2.5[V/m], and the high magnetic fields are largely localized to the intermediate section of the GIS and their amplitudes are [$1.2~39.5\mu$T]. Metal enclosures of transform and GIS play a role in reducing the electric field, and the magnetic fields are characterized by a rapid decrease with distance from the transformer and GIS enclosures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.46-54
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• 1999

In recent years, the electromagnetic enviroments are varied with the increase of power consumption and the spread of hoosehold electric appliances. Most of the interests to date have concentrated in the area of human health effects associated with exposure to power frequency electric and rmgretic fields, and thus the precise measurement and analysis are required. In this paper, the measurements and analysis of the extremdy low frequency(ElF) electric and magnetic fields produced by actual 22.9[kV] distribution lines were performed. The experiIrents have been carried rot by lateral rrofile, and the thooretical analyses were made by use of FIELDS program fer the sake of comparison with the experimental data. Electric and magnetic field intensity were strong under power distrib.rticn lines, and were inversely proportional to lateral distance. The pufiles of electric and magnetic fields were M and $\bigcap$ shapes, respectively. and the rreasured data were good in agreemnt with the thooretical results. Both the electric and magnetic field intensity were iocreased with increasing the measurement height.height.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.359-368
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• 1998

One of the topics concerning the electromagnetic compatibility of modern electronic circuits is to take protection from transient overvoltages caused by not only cloud-to-ground lightnings but also induced lightning discharges. In this paper, the vertical electric and horizontal magnetic fields from cloud-to-ground lightnings were measured and analyzed. The electric and magnetic fields waveforms associated with cloud-to-ground lightnings have several subsidiary peaks which decrease with time. There were not much differences between the electric and magnetic field due to long distance cloud-to-ground discharges. Average values of 10~90% rise times of electric fields are $4.65mutextrm{s}$ for the positive cloud-to-ground lightning and $3.29mutextrm{s}$ for the negative cloud-to-ground lightning, respectively. Also, in the positive and negative cloud-to-ground lightning discharges, the zero-to-zero crossing times in the wave tail of magnetic fields are significantly longer than those of the electric fields.

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.309-311
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• 2001

Strong thermal X-ray emission, called Galactic Ridge X-ray Emission, is observed along the Galactic plane (Koyama et al. 1986). The origin of hot ($\~$7 keV) component of GRXE is not known, while cool ($\~$0.8 keV) one is associated with supernovae (Kaneda et al. 1997, Sugizaki et al. 2001). We propose a possible mechanism to explain the origin; locally strong magnetic fields of $B_{local}\;\~30{\mu}G$ heat interstellar gas to $\~$7 keV via magnetic reconnection (Tanuma et al. 1999). There will be the small-scale (< 10 pc) strong magnetic fields, which can be observed as $(B)_{obs} \;\~3{\mu}G$ by integration of Faraday Rotation Measure, if it is localized by a volume filling factor of f $\~$ 0.1. In order to examine this model, we solved three-dimensional (3D) resistive magnetohydrodynamic (MHD) equations numerically to examine the magnetic reconnect ion triggered by a supernova shock (fig.l). We assume that the magnetic field is Bx = 30tanh(y/20pc) $\mu$G, By = Bz = 0, and the temperature is uniform, at the initial condition. We put a supernova explosion outside the current sheet. The supernova-shock, as a result, triggers the magnetic reconnect ion, and the gas is heatd to > 7 keV. The magnetic reconnect ion heats the interstellar gas to $\~$7 keV in the Galactic plane, if it occurs in the locally strong magnetic fields of $B_{local}\;\~30{\mu}G$. The heated plasma is confined by the magnetic field for $\~10^{5.5} yr$. The required interval of the magnetic reconnect ions (triggered by anything) is $\~$1 - 10 yr. The magnetic reconnect ion will explain the origin of X-rays from the Galactic ridge, furthermore the Galactic halo, and clusters of galaxies.

• Resources Recycling
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• v.27 no.6
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• pp.11-22
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• 2018

Magnetic separators has been used in the mining and the recycling fields in general, and is still applied in wide variety of fields. It is classified into the equipments for separating coarse ferrous scrap from non-ferrous materials and the equipments for concentrating fine ferromagnetic particles below 3mm. Magnetic separation equipments for concentrating fine materials also falls into two categories of low intensity and high intensity magnetic separators. The former is used for ferromagnetic materials but also paramagnetic materials of high magnetic susceptibility, and the latter for paramagnetic materials of lower magnetic susceptibility. Both low and high intensity magnetic separators could be utilized either dry and wet. Recently, the High gradient magnetic separators(HGMS) used in the range of less than 0.7 tesla has been gradually replaced by the magnetic separator made of rare earth permanent magnets commercialized in the 1980s. In addition, the expansion of nanotechnology in terms of synthetic magnetic materials in the environmental and biological fields is expected to contribute positively to the development of magnetic separation technology.

• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.343-347
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• 2004

The energy injection of galactic black holes (BH) into the intergalactic medium via extragalactic radio source jets and lobes is sufficient to magnetize the IGM in the filaments and walls of Large Scale Structure at < [B] > ${\~}0.l{\mu}G$ or more. It appears that this process of galaxy-IGM feedback is the primary source of IGM cosmic rays(CR) and magnetic field energy. Large scale gravitational infall energy serves to re-heat the intergalactic magnetoplasma in localities of space and time, maintaining or amplifying the IGM magnetic field, but this can be thought of as a secondary process. I briefly review observations that confirm IGM fields around this level, describe further Faraday rotation measurements in progress, and also the observational evidence that magnetic fields in galaxy systems around z=2 were approximately as strong then, ${\~}$10 Gyr ago, as now.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.846-848
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• 2002

A large-area (830mm ${\times}$ 1,020mm) inductively coupled plasma source with a six internal straight antennas was developed for large area FPD etch process applications and the effects of magnetic fields employing permanent magnets on the plasma characteristics were investigated. By employing the magnetic fields perpendicular to the six straight antenna currents using permanent magnets, improved plasma characteristics such as increase of the ion density and decrease of both electron temperature and plasma potential could be achieved in addition to the stability of the plasma possibly due to the reduction of the electron loss. However, the application of the magnetic field decreased the plasma uniformity slightly even though the uniformity within 10% could be maintained in the 800mm processing area.

• Journal of Magnetics
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• v.21 no.1
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• pp.102-109
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• 2016

In this paper, the theoretical and experimental characteristics of magnetic and electric fields in the vicinity of high voltage lines are investigated. To realize these measurements and calculations, we have developed some equations for two overhead power line configurations of 150 kV (single circuit, double circuit), based on Biot-savart law, image and Maxwell theories, in order to calculate the magnetic and electric fields. The measurements were done to a maximum distance from the tower of 50 m, at a height of 1m from the ground. These experiments take into consideration the real situations of the power lines and associated equipment. The experimental results obtained are near to that of the Biot-Savart theoretical results for a far distance from the tower; and for a distance close to the power line, the results from the image theory are in good agreement with the experimental results.