• Journal of Magnetics
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• 제17권2호
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• pp.133-137
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• 2012

We investigated the effects of pulsed magnetic fields (PMF) stimulus on electroencephalogram (EEG) alpha activity and heart rate variability (HRV) from electrocardiogram (ECG) measurements with various stimulus durations at acupoint PC9. The alpha activity in the EEG and the ratio of low frequency power and high frequency power (LHR) in the HRV, a reflection of sympathovagal activity, were increased and decreased, respectively, after PMF stimulus of 3 min. Our spectral analysis quantitatively proved that the changes in the EEG alpha activity were consistent with an autonomic function in the ECG. These findings suggest that appropriate PMF stimulus results in the same effect as that of acupuncture applied to the acupoint PC9, which is closely related to the parasympathetic activity of the autonomic nervous system.

• Journal of Astronomy and Space Sciences
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• 제30권2호
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• pp.101-106
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• 2013

The length of solar cycle 23 has been prolonged up to about 13 years. Many studies have speculated that the solar cycle 23/24 minimum will indicate the onset of a grand minimum of solar activity, such as the Maunder Minimum. We check the trends of solar (sunspot number, solar magnetic fields, total solar irradiance, solar radio flux, and frequency of solar X-ray flare), interplanetary (interplanetary magnetic field, solar wind and galactic cosmic ray intensity), and geomagnetic (Ap index) parameters (SIG parameters) during solar cycles 21-24. Most SIG parameters during the period of the solar cycle 23/24 minimum have remarkably low values. Since the 1970s, the space environment has been monitored by ground observatories and satellites. Such prevalently low values of SIG parameters have never been seen. We suggest that these unprecedented conditions of SIG parameters originate from the weakened solar magnetic fields. Meanwhile, the deep 23/24 solar cycle minimum might be the portent of a grand minimum in which the global mean temperature of the lower atmosphere is as low as in the period of Dalton or Maunder minimum.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3327-3332
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• 2011

Antimicrobial peptides have recently gained the much attention because of their ability to make defense system from attacking bacterial infections. Drosocin has been considered as very attractive antibiotic agents because of low toxicity against human erythrocytes and active at the low concentration. We have studied the structureactivity relationship of a glycopeptide drosocin focused on the N-acetyl-D-galactoside at $Thr^{11}$ residue. Based on the radial diffusion assay, we found that the acetylation of carbohydrate moiety increased the antimicrobial activity and the $Pro^{10}$, present in the middle of drosocin plays an important role in the antimicrobial activity. Our results provide a good lead compound for further studies on the design of drosocin-based analogues targeting glyco linked Thr site.

• 한국산업보건학회지
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• 제24권4호
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• pp.509-517
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• 2014

Objectives: This study was conducted to investigate the patterns of exposure of welders to strong magnetic fields for extended periods of time on the basis of their daily activities as recorded in a logbook. Methods: Male workers whose main job is welding, specifically seven welders occupied with gas tungsten arc welding(GTAW), two performing shielded metal arc welding(SMAW), and ten engaged in gas metal arc welding(GMAW), were measured in terms of the degree to which they were exposed to extremely low frequency(ELF) magnetic fields over 24 hours by using an electromagnetic field meter(EMF meter), as well as based on a daily activity log. Results: The welders were exposed to $1.25{\pm}4.95{\mu}T$ of magnetic field per day on average. For those who spent more than half a day-735.26 minutes, or 51.1% of the day-at work, the figure averages $3.88{\pm}8.85{\mu}T$ with a maximum value of $221.28{\mu}T$. The subject welders spent $338.14{\pm}154.95$ minutes per day at home. During their stays at home, they were exposed to an average of $0.17{\pm}0.06{\mu}T$ with a maximum value of $3.50{\mu}T$. The maximum exposure of $221.28{\mu}T$ occurred when welders performed GMAW. The average exposure reached its highest at $17.71{\pm}6.96{\mu}T$ when conducting SMAW. Magnetic field exposure also depends upon posture: welders who sat while welding were exposed five times more than those who stood during work, and this difference is statistically significant. As for the relationship between distance from the welding power supply and maximum magnetic field exposure, maximum magnetic field exposure decreases as the distance increases. The average magnetic field exposure, in the meantime, showed no significant difference depending on distance. Conclusions: The following were observed through this study: 1) welders, while conducting jobs, are exposed to magnetic fields not only from the welding machine, but also from the surrounding base material due to the current flowing between the welding machine and base material, meaning that they are continuously exposed to a magnetic field; and 2) welders are more exposed to magnetic fields while they sit at a job compared to when they stand up.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.231-239
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• 2013

To identify seasonal and latitudinal variations of F2 layer during magnetic storm, we examine the change of daily averages of foF2 observed at Kokubunji and Hobart during high (2000~2002) and low (2006~2008) solar activity intervals. It is found that geomagnetic activity has a different effect on the ionospheric F2-layer electron density variation for different seasons and different latitudes. We, thus, investigate how the change of geomagnetic activity affects the ionospheric F2-layer electron density with season and latitude. For this purpose, two magnetic storms occurred in equinox (31 March 2001) and solstice (20 November 2003) seasons are selected. Then we investigate foF2, which are observed at Kokubunji, Townsville, Brisbane, Canberra and Hobart, Dst index, Ap index, and AE index for the two magnetic storm periods. These observatories have similar geomagnetic longitude, but have different latitude. Furthermore, we investigate the relation between the foF2 and the [O]/[$N_2$] ratio and TEC variations during 19-22 November 2003 magnetic storm period. As a result, we find that the latitudinal variations of [O]/[$N_2$] ratio and TEC are closely related with the latitudinal variation of foF2. Therefore, we conclude that the seasonal and latitudinal variations of foF2 during magnetic storm are caused by the seasonal and latitudinal variations of mean meridional circulation of the thermosphere, particularly upwelling and downwelling of neutral atmosphere during magnetic storm.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
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• pp.113-113
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• 2003

A number of studies have demonstrated recently nonthermal interactions of extremely low frequency electromagnetic fields with cellular systems, such as the cells of the immune system. Particular concern came from epidemiological findings, which correlated environmental exposure of human body to weak electromagnetic fields with an elevated risk for developing certain type of leukemias and cancers. Several home/environmental sources generating extremely low frequency electromagnetic fields, such as 50 - 60 Hz high-voltage transmission lines, video display terminals, electric blankets, clinical nuclear magnetic resonance imaging procedures, etc., may interact with the human body. In this study we examined the effects of static magnetic fields (SMF) on the phagocytosis of the murine peritoneal macrophages (C57BL/6). The cells were exposed in vitro for 24 h at 37$^{\circ}C$ to 400 G SMF. The phagocytic activity of peritoneal macrophages was determined with a luminometer. Exposure to the SMF decreased phagocytic activity of murine peritoneal macrophages. In order to provide a more exact mechanism of the phenomenon, we analyzed peritoneal macrophages for alteration in their proteomes. The expression levels of these 5 proteins were increased in the SMF. In total 5 proteins which were differentially expressed in the SMF compared with control group were identified. The expression levels of these 5 proteins were increased in the SMF.

• 천문학논총
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• 제15권spc1호
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• pp.93-102
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• 2000

We have reviewed the magnetic activity in close binaries. Solar like magnetic activity indicators such as photometric spots, chromo spheric emission, coronal X-ray and radio emission, and flare activity are commonplace in many cool stars with convective envelopes. Using the UV spectra we confirmed the strength of stellar activity increases with more rapid rotation and later spectral types which corresponds to the increasing depth of the star's convective envelope. Apart from very young stellar objects such as T Tauri stars, the stars with the highest levels of activity are close binary systems composed of cool stars, i.e., the chromospherically active binaries such as RS CVn, BY Dra, W UMa and related systems. The IUE low and high dispersion spectra of V711 Tau, VW Cep and SW Lac are used for ultraviolet photometry and for a variation study of chromospheric activity. Evidence of chromospherically activity is indicated by the intensity variation of the Mg II emission line with orbital phase.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.1-5
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• 2020

Heart consists of myocardium cells and the electrophysiological activity of the cells generate magnetic fields. By measuring this magnetic field, magnetocardiogram (MCG), functional diagnosis of the heart diseases is possible. Since the strength of the MCG signals is weak, typically in the range of 1-10 pT, we need sensitive magnetic sensors. Conventionally, superconducting quantum interference devices (SQUID)s were used for the detection of MCG signals due to its superior sensitivity to other magnetic sensors. However, drawback of the SQUID is the need for regular refill of a cryogenic liquid, typically liquid helium for cooling low-temperature SQUIDs. Efforts to eliminate the need for the refill in the SQUID system have been done by using cryocooler-based conduction cooling or use of non-cryogenic sensors, or room-temperature sensors. Each sensor has advantage and disadvantage, in terms of magnetic field sensitivity and complexity of the system, and we review the recent trend of MCG technology.

• Macromolecular Research
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• 제16권7호
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• pp.637-643
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• 2008

A combination of magnetic and temperature-responsive properties in the same polymer composites is expected to increase their potential applications in the biomedical field. Accordingly, micron-sized magnetite/polystyrene/poly(2-dimethylaminoethyl methacrylate-ethyleneglycol dimethacrylate), which are abbreviated as $Fe_3O_4$/PS/P (DM-EGDM) composite polymer particles, were prepared by the seeded copolymerization of DM and EGDM in the presence of magnetite/polystyrene ($Fe_3O_4$/PS) particles. $Fe_3O_4$/PS/P(DM-EGDM) composite particles with magnetic properties showed a temperature-sensitive phase transition at approximately $31^{\circ}C$. The adsorption behavior of the low molecular weight emulsifiers and trypsin (TR) as biomolecules were examined on $Fe_3O_4$/PS/P(DM-EGDM) composite polymer particles at different temperatures. The native conformation of TR was followed by measuring the specific activity under various adsorption conditions. The activity of the adsorbed TR on composite polymer particles was higher than those of the tree TR and TR adsorbed on $Fe_3O_4$/PS particles.

• 천문학회보
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• 제41권2호
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• pp.67.1-67.1
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• 2016

We examined the relations between CME speed and properties of magnetic helicity in the source region such as helicity injection rate and total unsigned magnetic flux, which reflect the magnetic energy in the active region. For this, we selected 22 CMEs occurred during the increasing phase of solar cycle 24, which shows extremely low activities and classified them into two groups according to evolution pattern of helicity injection rate. We then compared the relations with those from previous study based on the events in solar cycle 23. As the results, we found several properties as follows: (1) Both of CME speed and helicity parameters have very small values since we only considered increasing phase; (2) among 22 CMEs, only 6 events (27%) are classified as group B, which show sign reversal of helicity injection and they follow behind of appearance of group A events. This fact is well coincide with the trend of solar cycle 23 that only group A events was observed in the first 3 years of the period; (3) as the solar activity is increasing, the CME speed and helicity parameters are also increasing. Based on the observations of solar cycle 23, the helicity parameters was still increasing in spite of decreasing solar activity after maximum period.