• 대한전기학회논문지:전력기술부문A
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• 제53권8호
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• pp.461-465
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• 2004

This paper analysed the induced current density by electric field of human body under the 765 kV transmission line considering permittivity and conductivity. As permittivity of human body is very high as $10^6$ at 60 Hz, special numerical computation technique in Surface Charge Method(SCM) for composite media with extremely different properties is applied to reduce calculation error of induced current density and electric field inside the human body. Calculation results show that the average of the induced current density inside human body is about 3mA/$m^2$, which is less than ICNIRP criterion (10mA/$m^2$).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1987-1989
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• 2000

In this paper, electric field distribution of dielectric sphere considering surface or volume resistivity is analysed by the use of rotational symmetric charge simulation method. We applied three methods such as ${\alpha},{\beta}$ modified $\beta$ method to check electric field calculation error. We find f method and modified $\beta$ method are suitable to simulate volume and surface resistivity respectively.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1577-1583
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• 2018

Tumor-treating fields therapy involves placing pads onto the patient's skin to create a low- intensity (1 - 3 V/cm), intermediate frequency (100 - 300 kHz), alternating electric field to treat cancerous tumors. This new treatment modality has been approved by the Food and Drug Administration in the USA to treat patients with both newly diagnosed and recurrent glioblastoma. To deliver the prescribed electric field intensity to the tumor while minimizing exposure of organs at risk, we developed an optimization method for the electric field distribution in the body and compared the electric field distribution in the body before and after application of this optimization algorithm. To determine the electric field distribution in the body before optimization, we applied the same electric potential to all pairs of electric pads located on opposite sides of models. We subsequently adjusted the intensity of the electric field to each pair of pads to optimize the electric field distribution in the body, resulting in the prescribed electric field intensity to the tumor while minimizing electric fields at organs at risk. A comparison of the electric field distribution within the body before and after optimization showed that application of the optimization algorithm delivered a therapeutically effective electric field to the tumor while minimizing the average and the maximum field strength applied to organs at risk. Use of this optimization algorithm when planning tumor-treating fields therapy should maintain or increase the intensity of the electric field applied to the tumor while minimizing the intensity of the electric field applied to organs at risk. This would enhance the effectiveness of tumor-treating fields therapy while reducing dangerous side effects.

• Journal of Information Display
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• 제10권4호
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• pp.158-163
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• 2009

There are two kinds of well-known electron emissions from metal: field and thermionic emission. For thermionic emission, electrons come out of a metal due to the thermal energy, whereas for field emission, electrons tunnel out of a metal through the strong electric field. In this study, the most general electron emission caused by the temperature and electric field with a free electron gas model was considered. The total current density of electron emission comes from the field emission effect, where the electron energy is lower than vacuum, and from the thermionic-emission effect, where the electron energy is higher than vacuum. The total current density of electron emission is shown as a function of the temperature for a constant electric field, and as a function of the electric field for a constant temperature.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.485-491
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• 2002

Since Wertheimer and Leeper reported possible adverse health effects of magnetic field in 1979, worldwide researches on this issue have been conducted. More recently, the U.S. Congress instructed the NIEHS (National Institute of Environmental Health Sciences), NIH (National Institute of Health) and DOE (Department of Energy) to direct and manage EMF RAPID (Electric and Magnetic Fields Research and Public Information Dissemination) program aimed at providing scientific evidence to clarify the potential for health risks from exposure to extremely low frequency electric and magnetic fields(ELF-EMF). Although they concluded that the scientific evidence suggesting adverse health risks of ELF-EMF is weak, the exposure to ELF-EMF cannot be recognized as entirely safe. Therefore, the purpose of this article is to describe magnetic field 3-D calculation and to evluate eddy current of human body compare to international guide line recognized one of the basic problems. In open boundary problem, Magnetic field using FEM is not advantageous in the point of the division of area and the proposition of the fictitious boundary. Therefore, we induced the analytic equation of magnetic field calculations so but the finite line segment based on Biot-Savarts law Also, Eddy currents induced due to ELF-EMF magnetic field are computed. To calculate induced currents, impedance method is used in this paper, An example model of human head with resolution of 1.27cm is used. In this paper, We evaluate the magnetic field and eddy current of human head around 765 kV transmission lines compare to international guide line.

• 한국안전학회지
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• 제19권2호
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• pp.34-40
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• 2004

This paper presents an analysis of SAR(Specific Absorption Rate) distribution characteristics in a head model using FDTD(Finite Difference Time Domain). In this study human head was modelled in four elements-layered structure, consisting of skin, fat, skull and brain. To calculate the electromagnetic fields wihtin the head model, FDTD method was used. In the FDTD method, the electromagnetic wave is analyzed by solving a Maxwell's equations repeatedly. For the calculation, distance between power source and head model increased by 10[m]. Power density and incident electric field intensity were calculated. Based on the incident electric field, the program which calaculated internal electric fields intensity and SAR calculation of the head model were developed. The results of developed program using FDTD were compared with those of a commericial programs, which showed the availability and usefulness of the suggested scheme in this paper.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.977-982
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• 2012

In order to find out partial discharge (PD) phenomena in the cable joint due to the poor workmanship during the installation, the relationship between PD inception voltages and joint defects was investigated. For the purpose, in the joint of 22.9kV CNCV cables, electric fields were calculated for various semiconductive layer wrong positioning (WP) defects. And, PDIV were investigated through the experiments and compared with the results of electric field analysis. In all WP defect cases, the PD inception field calculated using measured PDIVs was similarly shown to be the average value of 1.84kV/mm. In addition, the calculated PDIV and the measured PDIV were almost equal, from the PDIV calculation using maximum electric fields and the measured PDIV for the normal case. Throughout this study, it is possible to analyze WP defects due to the poor workmanship and to establish better joint design for the distribution grade extruded cable system.

• KEPCO Journal on Electric Power and Energy
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• 제3권2호
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• pp.119-125
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• 2017

Regarding the implementation of ROMM project (Rehabilitation, Operation, Maintenance & Management), which is one of overseas development projects, it is very important to diagnose the exact current status of aged thermal power plant. However, when people visit the power plant for the purpose of prediagnosis to implement the ROMM project, most target power plants for diagnosis, in general, are under operation. This can be a big interference factor to diagnose the exact current status of power plants. Therefore, in order to solve such interference factor, based on the 30 years of know-how in the field, the present study has developed a regression curve for a simple life time assessment and the calculation of rehabilitation cost that may be used as a reference relatively for the quantitative diagnosis on the status of a relevant power plant even during the operation of the power plant.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.172-176
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• 1997

It is likely that the corona discharge appears due to the motion and the multiplication of electron and ion under the nonuniform electric field. Because the motion and the multiplication of electron and ion are the function of electric field, for the simulation of the corona discharge, we have to calculate the electric field, before the calculation of the motion and the multiplication of electron and ion. In this paper, the electric field is calculated on the assumption that the gap between a hyperboloidal needle and a plane is 1-dimension, and the motion and the multiplication of electron and ion are determined by Flux-Corrected Transport method. For this purpose, we solve the electron and ion continuity equation together with Poisson equation. We calculated the current density and the electron and ion density distributions between electrodes as well as electric field distortion due to the space charge assuming that the discharge channel radius is 100${\mu}{\textrm}{m}$. In this simulation, it is found that the current density has one peak as observed by experiment, and electric field distortion is important to the formation and the stability of the corona discharge.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.2089-2097
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• 2014

Negative corona onset characteristics of the stranded conductors based on the ultra-high voltage (UHV) corona cage were studied in the paper. Based on the corona self-sustaining criterion in extreme uneven electric fields and the secondary emission process of the photoelectrons, the corona onset calculation model in the UHV corona cage is established and the corona current tests of the single LGJ900-75, 6 bundle LGJ900-75, 8 bundle LGJ400-35 conductors in dry and rain conditions were done in the UHV corona cage, and the rain rates are 2.4 mm/h, 20 mm/h and 30 mm/h. Corona onset electric field strength is gained by E-I tangent method, and the onset electric field strength in dry condition proves that the calculation model can be used to calculate the corona onset characteristics of the bundle conductors in the UHV corona cage. A further analysis proves that: the negative corona onset voltage of the conductor increases with the bundle number and the diameter of the sub conductor, but decreases with the bundle space in the corona cage. The onset electric field strength is influenced little by bundle space and bundle number, but decreases with the increase of the diameter of the sub-conductor. The surface irregularity coefficient decreases with the rain rate.