• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.144-148
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• 2001

A geophysical and geochemical study was performed to verify the depth of landfill as well as the horizontal/vertical distribution of leachate at the landfill site located in Gongju. The electrical resistivity, with dipole-dipole array and dipole spacing of 5m, was applied along the nine survey lines and electromagnetic induction survey was conducted along the perimeter traverse surrounding the landfill. Cations, anions and stable isotope ($\delta$D and $\delta$$^{18}$ O) analyses were performed on about 63 water and leachate samples collected in dry and rainy seasons at 31 sites. The result of electromagnetic induction survey make it possible to derive the potential route of leachate in the past or present. The imaging of processed resistivity field data show that the possible route of leachate doesn't exist except the survey line 7. The weak zone traversing the landfill, however, is revealed by the electrical resistivity imaging, which may be the potential route of leachate toward the deep ground. The geochemical data agree well with geophysical data for deducing possible route of leachate of the site.

• Journal of Environmental Impact Assessment
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• v.15 no.4
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• pp.271-277
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• 2006

In this study, we investigated the applicable plan of GIS on the environmental impact assessment of 60 Hz Powerline. So we assessed distance data based on calculations by use of 2D and 3D Geographical information systems(GIS) and distance data based on measurements on 1: 5000 maps accord with on site distance measurements to use input data for calculating magnetic field. One hundred eight of the on site measured addresses were selected from residences. The data were achieved by measuring the distance between residence and power line on maps with scales of 1: 5000. The digital map was obtained from National Geographic Information Institute with scales of 1: 5000, and we made 2D and 3D map. Correlation analyses were performed for statistical analyses. For the 3D GIS versus on site comparison of different exposure categories, 70 of 108 measurements were assigned to the correct category. Similarly for 2D GIS versus on site comparison, 71 of 108 were correctly categorized. When comparing map measurement with on site measurement, 62 of 108 were correctly categorized. When the correlation analysis was performed, best correlation was found between 3D GIS and on site measurements with r = 0.84947 (p<0.0001). The correlation between map and on site measurement yielded an r of 0.76517 (p<0.0001). Since the GIS measurements and map measurement were made from the center point in the building and the on site measurements had to be made from the closest wall on the building, this might introduce and additional error in urban areas. The difference between 2D and 3D calculations were resulted from the height of buildings.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.523-528
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• 2013

Background: The possibility that electromagnetic fields (EMF) exposure may increase male breast cancer risk has been discussed for a long time. However, arguments have been presented that studies limited by poor quality could have led to statistically significant results by chance or bias. Moreover, data fo the last 10 years have not been systematically summarized. Methods and Results: To confirm any possible association, a meta-analysis was performed by a systematic search strategy. Totals of 7 case-control and 11 cohort studies was identified and pooled ORs with 95% CIs were used as the principal outcome measures. Data from these studies were extracted with a standard meta-analysis procedure and grouped in relation to study design, cut-off point, exposure assessment method, adjustment and exposure model. A statistical significant increased risk of male breast cancer with EMF exposure was defined (pooled ORs = 1.32, 95% CI = 1.14-1.52, P < 0.001), and subgroup analyses also showed similar results. Conclusions: This meta-analysis suggests that EMF exposure may be associated with the increase risk of male breast cancer despite the arguments raised.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.89-91
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• 2008

This paper deals with the thrust calculations and the measurements of a cylindrical Linear Oscillatory Actuator (LOA) sing Transfer Relations Theorem (TRT), namely, Melcher's methodology. Using transfer relations derived in terms of a magnetic vector potential and a two-dimensional (2-d) cylindrical coordinate system, this paper derives analytical solutions for the magnetic vector potential, magnetic fields due to Permanent Magnets (PMs) and stator winding currents and the thrust. The analytical results are validated by non-linear Finite Element (FE) analyses. In particular, test results such as thrust and back-emf measurements are given to confirm the analysis.

• 전기의세계
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• v.21 no.3
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• pp.7-18
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• 1972

An analysis is made for the performance of twin stator single-phase induction machine having any movable asymmetrical angle of stator windings, with any symmetrical or asymmetrical magnetizing reactance and winding turn-ratio between two stators, provided that asymmetrical common squirrel cage rotor is utilized. This mechanism is a new type, which has the advantage of mading only not the performance prediction in applications as a single-phase electromagnetic driving mechanism but also the analysis prediction of single-phase induction motor with not in quadrature axis. The basis of the analyses are lead by Kron's primitive machine matrix and Morrill's double-revolving field concept. All the performances can be calculated from the test values and design details of the asymmetrical magnetizing reactance twin stator single-phase induction machine and verified by test. And its validity is still demonstrated to the pure twin stator single-phase induction machine.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.864-869
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• 2008

Magnetic Levitated(Maglev) Vehicle, which utilizes electromagnetic forces between dual-pole electromagnets and a steel rail, generally runs on guideway structures. A prototype of an Urban Maglev Vehicle has been developed and tested in Korea, This study was conducted as a cooperation research subject of the 3-1 subject, performance improvement of maglev track structures, of the Center for Urban Maglev Program, statred in 2006. As the Maglev load is distributed rather than concentrated, a field test was conducted on Simple Span PSC-BOX Girder Bridge(L=25.0m) of the Expo-Maglev test track in Daejeon to examine the dynamic effect of the Maglev load on the bridge. Numerical analyses were also performed up to the maximum passing speed of 110 km/h by 10 km/h increments of Maglev Vehicle using Finite Element model of bridge, and girder deflections, accelerations and Dynamic Amplification Factor (DAF) are analysed.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.21-34
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• 2017

The ground penetrating radar (GPR) signal can be measured with different amplitudes according to the directivity, so the directivity of the antenna should be considered. The objective of this study is to investigate the directivity of antenna by analyzing the reflection characteristics of electromagnetic waves radiated from the antenna, and to evaluate effective range of angle that can inspect an abnormal area according to the directivity of antenna. For the measurement of the directivity, a circular metal bar is used as reflector and the signals are measured by changing the angle and the distance between reflector and antenna in the E- and H-plane. The boundary distance between the near field and the far field is determined by analyzing the amplitudes of reflected signals, and two points with different distances from each of near and far fields are designated to analyze radiation patterns in near and far fields. As a result of radiation pattern measurement, in the near field, minor lobes are observed at angle section at more than $50^{\circ}$ in both E- and H-plane. Therefore, antenna has the directivity for the direction of main lobe and minor lobes in near field. In the far field, antenna has the directivity for a single direction of main lobe because minor lobes are not observed. The amplitude of the signal reflected from the near field is unstable, but it can be distinguished from noise. Therefore, in the near field, the ground anomaly can be detected with high reliability. On the other hand, the amplitude of the signal reflected from the far field is stable, but it is hard to distinguish between reflected signal and noise because of the excessive loss of electromagnetic wave. The analyses of directivity in the near and the far fields performed in this study may be effectively used to improve the reliability of the analyses of abnormal area.

• Environmental Analysis Health and Toxicology
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• v.30
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• pp.15.1-15.11
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• 2015

Objectives There has been a growing concern about the possible carcinogenic effects of the electromagnetic radiofrequency fields emitted from mobile phones. The purpose of this study was to investigate the association between mobile phone use and the development of gliomas in Korea. Methods Our study methods were based on the International Interphone study that aimed to evaluate possible adverse effects of mobile phone use. This study included 285 histologically-confirmed Korean patients 15 to 69 years of age, with gliomas diagnosed between 2002 and 2007 in 9 hospitals. The 285 individually matched controls were healthy individuals that had their medical check-up in the same hospitals. Unconditional logistic regression was used to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for use of mobile phones. Results For the entire group, no significant relationship was investigated between gliomas and regular use of mobile phones, types of mobile phones, lifetime years of use, monthly service fee, and the other exposure indices. Analyses restricted to self-respondents showed similar results. For ipsilateral users, whose the body side for usual mobile phone use match the location of glioma, the aORs (95% CIs) for lifetime years of use and cumulative hours of use were 1.25 (0.55 to 2.88) and 1.77 (0.32 to 1.84), respectively. However, the contralateral users showed slightly lower risk than ipsilateral users. Conclusions Our results do not support the hypothesis that the use of mobile phones increases the risk of glioma; however, we found a non-significant increase in risk among ipsilateral users. These findings suggest further evaluation for glioma risk among longterm mobile phone users.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.217-222
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• 2014

This paper discusses about the beam pattern distortion caused by the failures of some antenna modules in the active array antenna and analyses the possibility of improvement through applying the beam pattern compensation method previously studied. The beam pattern distortion which is mostly represented as an increase of the sidelobe level, can be suppressed through re-synthesizing each module's magnitude and phase. This method was applied to the prototype of active array antenna system, and the results of antenna pattern distortion and compensation were analyzed and measured in the Near Field Chamber. Array failures are generally divided into random TR module failures and TRU(TR Unit: combination of TR modules, Beam Computation module, Power supply module) failures. The results of beam pattern compensation were analyzed in each failure and compared to the results of the simulation. The beam pattern compensation results applied to the real active antenna array system showed the similar to the simulation results. Consequently, it was verified the beam pattern could be compensated with the magnitude and phase adjustment of other normal antenna modules.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.29-34
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• 2021

In this paper, a cylindrical photonic crystal waveguide with a low-index core is first proposed. The core can be filled with air, liquid, or arbitrary dielectric materials. Exact analyses for the electromagnetic field characteristics of guided modes, by using appropriate Bessel functions and applying the boundary conditions, are performed to find out the guiding characteristics of the proposed waveguide. For verification and usage in design and manufacturing process, the computer-calculation of the waveguide transmission characteristics is also performed by applying the rigorous full-vectorial finite difference method. Providing variations of the effective area for the fundamental mode of the designed waveguide with different numbers of cladding layers, ranging from 2.6056 ㎛2 to 5.9673 ㎛2 over the operation wavelength, generally as the core refractive index n1 is higher, the mode area becomes smaller and the result leads to more optimistic effect for nonlinear device applications.