• Journal of Environmental Health Sciences
• /
• v.21 no.1
• /
• pp.78-85
• /
• 1995

Ornithine decarboxylase(ODC) is an indicate enzyme in carcinogenesis. We divided Sprague Dawley rats into six groups: control, electric field exposure, X-ray only irradiation, X-ray irradiation with electric field exposure group, Sr-90 injected group and Sr-90 and electric field complex exposure group. The ODC activity was measured in rat's bone marrow cell every week. The results were summarized as follows: The ODC activitied was increased in X-ray irradiated, Sr-90 injected and Sr-90 and electric field complex exposed group as compared with that of control(p<0.05). The ODC activity was increased comparing that of control neither in X-ray and electric field complex exposed group nor electric field only exposed group. This result suggests that the electric field doesn't have myeloid carcinogenicity and myeloid cancer incidence caused by ionized radiation is suppressed by electric field exposure.

• New Physics: Sae Mulli
• /
• v.68 no.11
• /
• pp.1225-1230
• /
• 2018

Schwinger pair production of electrons and positrons in a strong electric field is a prediction of nonperturbative quantum field theory, in which the out-vacuum is superposed of multi-particle states of the in-vacuum. Solving the Dirac or Klein-Gordon equation in the background field, though a linear wave equation, and finding the pair-production rate is a difficult or nontrivial job. The phase-integral method has recently been introduced to compute the pair production in space-dependent electric fields, and a complex analysis method has been employed to calculate the pair production in time-dependent electric fields. In this paper, we apply the complex analysis method to a Sauter-type electric field and other hyperbolic-type electric fields that vanish in the past and future and show that the Stokes phenomena in pair production occur when the time-dependent frequency for a given momentum has finite simple poles (polons) with pure imaginary residues.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.469-472
• /
• 2000

a crack with electrically impermeable surfaces in an electrostrictive material subjected to uniform electric loading is analysed. A strip yield zone model is employed to investigate the effect of electric yielding on stress intensity factor. complete forms of electric fields and elastic fields for the crack are derived by using complex function theory. /the stress intensity factors are obtained based on the strip yield zone model.

• Journal of the Korean Society of Safety
• /
• v.31 no.1
• /
• pp.48-53
• /
• 2016

This paper deals with analysis of complex grounding system using electromagnetic simulation method. Electrical devices could be damaged by transient voltage such as a lightning surge. Therefore the measures to protect the equipments from transient, such as a lightning are required. The ground system is important in this respect. The representative parameter of grounding system performance is earth ground resistance. Precise prediction of earth resistance is required, because it is difficult to modify and change after the completion of the grounding system construction. Numerical modeling is often used in numerical analysis to identify the electrical characteristics of the grounding system. However complex systems are difficult to predict grounding characteristics by numerical analysis. If the total electric field of the earth in general is similar to the antenna model, in that the incident electric field and expressed as a sum of the scattering field. In this study, the electromagnetic field simulation tool "ANSYS HFSS" module containing the antenna model was used to analyze performance of ground system. Both the simple and complex grounding system were analyzed by simulation tool and experimental method. As a result simulation method is effective to predict performance of a complex ground system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.2
• /
• pp.235-241
• /
• 2001

A crack with electrically conducting surfaces in a linear electrostrictive ceramic subjected to uniform electric fields is analyzed. Complete forms of electric fields and elastic fields for the crack are derived by using the complex function theory. The linear electromechanical theory predicts overlapping of the traction free crack surfaces. It is shown that the surfaces of the crack are contact near the crack tip. The contact zone size obtained on the basis of the linear dielectric theory for the conducting crack does not depend on the electric fields and depends on only the original crack and the material property for the linear electrostrictive ceramic.

• Journal of Biomedical Engineering Research
• /
• v.44 no.6
• /
• pp.377-383
• /
• 2023

Purpose: There is increasing attention to the application of transcranial direct current stimulation (tDCS) for enhancing cognitive functions in subjects to aging, mild cognitive impairment (MCI), and Alzheimer's disease (AD). Despite varying treatment outcomes in tDCS which depend on the amount of current reaching the brain, there is no general information on the impacts of anatomical features associated with AD on tDCS-induced electric field. Objective: The objective of this study is to examine how AD-related anatomical variation affects the tDCS-induced electric field using computational modeling. Methods: We collected 180 magnetic resonance images (MRI) of AD patients and healthy controls from a publicly available database (Alzheimer's Disease Neuroimaging Initiative; ADNI), and MRIs were divided into female-AD, male-AD, female-normal, and male-normal groups. For each group, segmented brain volumes (cerebrospinal fluid, gray matter, ventricle, rostral middle frontal (RMF), and hippocampus/amygdala complex) using MRI were measured, and tDCS-induced electric fields were simulated, targeting RMF. Results: For segmented brain volumes, significant sex differences were observed in the gray matter and RMF, and considerable disease differences were found in cerebrospinal fluid, ventricle, and hippocampus/amygdala complex. There were no differences in the tDCS-induced electric field among AD and normal groups; however, higher peak values of electric field were observed in the female group than the male group. Conclusions: Our findings demonstrated the presence of sex and disease differences in segmented brain volumes; however, this pattern differed in tDCS-induced electric field, resulting in significant sex differences only. Further studies, we will adjust the brain stimulation conditions to target the deep brain and examine the effects, because of significant differences in the ventricles and deep brain regions between AD and normal groups.

• Journal of the Korean Ceramic Society
• /
• v.39 no.1
• /
• pp.16-20
• /
• 2002

Semiconducting (Ba.Sr)TiO$_3$ceramic device, which shows the PTCR effect, has been usually used as a current limiter. In this case, the device should endure the condition under the high electric field. In this study, the dynamic electrical properties of the PTCR device under high voltage has been evaluated. Two different formulated powders were used and the sintered bodies exhibited the different grain size and porosity. The wide range of characterization such as complex impedance spectroscopy, microstructure, I-V characteristics and voltage dependence of resistivity of the samples were performed. The PTCR effect of the specimen containing coarse grains was very sensitively dependent on the AC electric field, showing that it was inversely pro-portional to the grain boundary potential barrier. The withstanding voltage was proportional to the potential barrier of grain boundary.

• Journal of the Korean Society of Visualization
• /
• v.3 no.2
• /
• pp.45-50
• /
• 2005

Electro-osmotic flow (EOF) instability in a microchannel has been experimentally investigated using a micro-PIV system. The micro-PIV system consisting of a two-head Nd:Yag laser and cooled CCD camera was used to measure instantaneous velocity fields and vorticity contours of the EOF instability in a T-shape glass microchannel. The electrokinetic flow instability occurs in the presence of electric conductivity gradients. Charge accumulation at the interface of conductivity gradients leads to electric body forces, driving the coupled flow and electric field into an unstable dynamics. The threshold electric field above which the flow becomes unstable and rapid mixing occurs is about 1000V/cm. As the electric field increases, the flow pattern becomes unstable and vortical motion is enhanced. This kind of instability is a key factor limiting the robust performance of complex electrokinetic bio-analytical devices, but can also be used for rapid mixing and effective flow control fer micro-scale bio-chips.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.179.1-179.1
• /
• 2005

• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.1
• /
• pp.85-91
• /
• 2021

With the social atmosphere of respect for human life and the increasing interest in safety of field workers, research and development is underway in various ways to transform direct live method into indirect live method in the field of distribution. As part of this measure, it was necessary to convert electric pole and complex facilities work from machining power distribution to indirect live operation, and install a straight connecting sleeve that connects cut wires for by-pass method, but it failed to meet the tensile strength standard when constructing a sleeve constructed by direct method. In this paper, the design factors were derived based on the case of overseas similar sleeves and the tensile strength evaluation of each variable was performed, based on the analysis of these test results, the method for securing tensile strength of straight-line access sleeves for indirect running was presented.