• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1921-1927
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• 2014

A new method for optimizing the magnetic field gradient in the exciting coil of electronic anti-fouling (EAF) system is presented based on changing exciting coil size. In the proposed method, two optimization expressions are deduced based on biot-savart law. The optimization expressions, which can describe the distribution of the magnetic field gradient in the coil, are the function of coil radius and coil length. These optimization expressions can be used to obtain an accurate coil size if the magnetic field gradient on a certain point on the coil's axis of symmetry is needed to be the maximum value. Comparing with the experimental results and the computation results using Finite Element Method simulation to the magnetic field gradient on the coil's axis of symmetry, the computation results obtained by the optimization expression in this article can fit the experimental results and the Finite Element Method results very well. This new method can optimize the EAF system's anti-fouling performance based on improving the magnetic field gradient distribution in the exciting coil.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1445-1449
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• 2007

This paper presents the DOD (Drop-On-Demand) characteristic using the electrostatic field induced inkjet printing system. In order to achieve the DOD characteristic of electrostatic field induced inkjet printing, applied the bias voltage of 1.4 kV and the pulse voltage of $2.0\;kV\;{\sim}\;2.7\;kV$ using high voltage pulse generator. Electrostatic field induced droplet ejection is directly observed using a high-speed camera and for investigated DOD characteristic, CNT ink used. The electrostatic field induced inkjet head system has DOD characteristic using pulse generator which can be applied pulse voltage. The bias voltage has a good condition which form meniscus and has micro dripping mode for small size micro droplet. Also, the droplet size decreases with increasing the applied pulse voltage. This paper shows DOD characteristic at electrostatic field induced inkjet head system, Therefore. electrostatic DOD inkjet head system will be applied industrial area comparing conventional electrostatic inkjet head system.

• Journal of The Korean Astronomical Society
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• v.14 no.1
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• pp.37-42
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• 1981

In order to know how the magnetic field increases with density in interstellar clouds, we have analyzed observations of extinction and polarization for stars in the ${\rho}$ Oph molecular cloud complex. The size of grains in dense parts of the complex is estimated to be larger than the ones in diffuse interstellar clouds by about 15 percent in radii. Employing the Davis-Greenstein mechanism for grain alignment with this estimated grain size, we have put constraints on the exponent in the field-density relation $B{\propto}n^x:1/5{\leq}x{\leq}1/3$. It is concluded that magnetic field in gravitationally contracting clouds increases less steeply than the classical expectation based on the approximation of isotropic contraction with complete frozen-in flux.

• KCID journal
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• v.21 no.1
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• pp.99-108
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• 2014

This study investigated the effects of NPS(non point source) pollution reduction of sediment traps through field experiments. Various sizes of 4 sediment traps were applied in a upland field located in Gunwi and assessed the infiltration and storage effects as well as NPS pollution reduction effects of this technique. The characteristics of deposited soil in the sediment traps were also analyzed including distribution of particle size, soil texture, and chemical properties. The results showed that slightly different composition of soil particle size from each sediment trap with high proportion of 0.15mm and 0.25mm ranges of soil particle diameters, while the loamy sand is the main types of deposited soils in the sediment traps. Decreased NPS pollution were observed from the water quality analysis of the samples taken from the sediment traps. Further research need to be proceeded continuously to improve this technique in order to utilize on upland fields for management of agricultural NPS pollutions.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.97-102
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• 1995

The ferromagnetic resonance properties of Mg ferrites which have various porosity grain size, and saturation magnetization are measured at one frequency. This allows a determination of the anisotropy field(Ha). The saturation magnetization multiplied by porosity is the resonance magnetic field. As the saturation magnetization increases, the linewidth decerases due to decrement of magnetic inhomogenity in sample. the porosity is a major factor broadening the linewidth for Mg ferrite when porosity is more thatn 6%, and the anisotropy field is dominant when porosity is less than 6%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.265-268
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• 2009

We present the experimental study to realize a DNA separation chip using asymmetrically-switched nonuniform electric fields. The DNA separation chip redistributes DNA molecules within a specific area based on the size- and field-dependent nonlinearity of DNA drift velocity. The present chip is composed of a width variable channel to distribute nonuniform electric field, a DNA loading slit and a pair of electrodes to apply electric field. We focus on the design of DNA separation chips with identifying the nonlinearity of DNA drift velocity using three different DNA molecules (11.1kbp, 15.6kbp, and 48.5kbp) in the chips. It is demonstrated that different size of DNA shows different net migration in different direction under the asymmetrically-switched nonuniform electric field.

• Journal of Magnetics
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• v.12 no.1
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• pp.31-34
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• 2007

The Co-based ribbons with different length were annealed in different magnetic field and GMI profiles were investigated in order to clarify the influence of ribbon size on GMI effect. The GMI ratio decreased with the decreasing in length and also decreased with increasing annealing field. While, the slope of GMI profiles inclined and the field range showing linearity was broadened. It shows prospect to low field sensor, especially for a navigation sensor.

• Progress in Medical Physics
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• v.24 no.2
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• pp.119-126
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• 2013

Due to the introduction of CR and DR, it has been neglected the use of the X-ray beam collimator and field size. This study examines nationwide survey of the proper use of collimator and field size by area in a specific field of plain radiography and the current status. Authors emphasized the need for the field size criteria, and propose a standard reference field size in each specific radiologic examination. Total 333 medical institutions (included in Seoul, Gyeonggi-do, Jeolla, Chungcheong, Gangwon-do, Busan area), were investigated in relation to the status of the X-ray beam collimation field size, type specific inspection areas, medical facilities, and image analyses by type to figure out whether they use the adjustment of image field to the specific examination. To assess the awareness and the impact of radiation exposure to the collimation adjustable, 168 radiographers who was working in 10 general hospitals, 10 hospitals, and 10 clinics, were surveyed how they haver adjusted the actual field size. We examine that 61.3% of medical institutions used the "Proper collimation" and only 49.9% of them employed proper one in lumbar spine densely crowded by major organs. 69% among general hospitals, and 65% among hospitals using DR system were using proper collimation. Radiographers recognized that proper adjustment of collimation could reduce the harmful radiation dose on patients. In the survey, 97.6% of respondents were aware of this fact, but only 83.3% of respondents did the adjustment of the size of the collimation field. The using of proper collimation field was low in the nationwide survey, so the effort to reduce the radiation dose on the patients is urgently needed. A unified standard for the field accompanied by thorough education should be needed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.2
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• pp.61-67
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• 2003

This paper describes a development of magnetic tomography system using two poles perpendicular magnetic field. In the system, the relative permeabilities of the object are detected by Hall sensors located along with tube circumference. The signals according to the size and position of the object could be separated in case the relative permeability of the object are over 10. Moreover, the size and location of the object could be determined in real time.

• Journal of the Korean Chemical Society
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• v.57 no.1
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• pp.159-164
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• 2013