The remote sensing technique of measuring the magnetic field was applied first to sunspots by Hale (1908). Later Babcock (1961) showed that the solar surface magnetic field on a global scale is a dipole in first-order approximation and that this dipole field reverses once every solar cycle. The Wilcox Solar Observatory (WSO) supplies the spherical harmonics coefficients of the solar corona magnetic field of each Carrington Rotation, calculated based on the remotely-sensed photospheric magnetic field of the solar surface. To infer the internal current system producing the global solar coronal magnetic field structure and evolution of the Sun, we calculate the multipole components of the solar magnetic field using the WSO data from 1976 to 2019. The prominent cycle components over the last 4 solar activity cycles are axis-symmetric fields of the dipole and octupole. This implies that the current inversion driving the solar magnetic field reversal originates from the equatorial region and spreads to the whole globe. Thus, a more accurate solar dynamo model must include an explanation of the origin and evolution of such solar internal current dynamics.

The purpose of this study is to investigate the ELF-MF emissions from UCLs and to compare the ELF-MF emission levels of HVTLs and UCLs. In addition, this study proposes a method and management plan to investigate the effects of exposure to ELF-MF emissions from UCLs. The ELF-MF emissions from the 154 kV UCL were 15.4±24.4 (GM: 7.8)mG, while from the 345 kV line they were 6.0±2.4 (GM: 5.7)mG. Through the comparison between ELF-MF emissions of 154 kV UCL and HVTL, at about 20 m distance from an overhead line the emissions level is 4 mG, while from an underground line at about 10 m distance the emission level was recorded as less than 4 mG. Through comparing the ELF-MF emission amount of the UCL according to the burial method, it was found that the direct ELF-MF emission levels are 15.3±7.4 (GM: 13.9)mG at the direct point, in the conduit type 21.0±30.4 (GM: 10.8)mG, and in the buried form 8.5±12.3 (GM:5.1)mG. In this study, ELF-MF emissions were about 37.0% and 47.5% lower, respectively, compared with the direct power and conduit type. The correlation between ELF-MF emission (mG) and power load (A) was analyzed. The higher the power load, the higher the ELF-MF emission. The correlation between ELF-MF emission at the direct point and depth of the UCL was also analyzed, and it was found that as the depth of line burial increased, ELF-MF emissions decreased.

We present results of our R-band polarimetry of a bright-rimmed cloud, IC1396A (with BRC 36), associated with the H II region S131 and the cometary globule LDN 1616 to study their magnetic field geometry. The distances of these clouds have been reported to be ~ 750 pc and ~ 450 pc, respectively in the literature. The young open cluster Trumpler 37 in the vicinity of IC1396A and the high mass stars in the Orion belt near L1616 are found to be responsible for the structure of these clouds. We made polarimetry of foreground stars inferred from their distances measured by the Hipparcos satellite to subtract the foreground contribution to the observed polarization results. We discuss the optical polarimetric results and compare our findings with MHD simulations towards BRCs and CGs.

In this study, ELF-MF levels of subway trains were measured to understand the status of the intensity of ELFMF. The measurement points for the train are selected in the center of each train compartment(pantagraph compartment, motor-driven compartment and the compartment that is not connected to any other electric equipment) using EMDEX II. ELF-MF levels of trains were measured from the starting to the terminal station in each lines(Seoul line 1-9, Incheon line 1, Incheon international airport line, Gyungui line, Bundang line, Gyeongchun line, Joongang line, Suin line). We found that the mean and range of ELF-MF levels in the DC power subway train are 2.4 and 0.1~125.9 mG, respectively, while the mean and range of ELF-MF levels in the AC power subway train are 10.4and 0.0~156.3 mG, respectively. Furthermore, the maximum ELF-MF level(156.3 mG) was lower than the reference level(ICNIRP 833 mG, 60Hz). The findings of this study in relation to the characteristics of ELF-MF for subway will be useful to derive the ELF-MF exposure coefficient from our living environment in a subsequent study.