• Journal of Magnetics
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• v.20 no.4
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• pp.353-359
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• 2015

Dielectric properties of $xBaTiO_3-(1-x)CoFe_2O_4$ composite materials have been investigated. Dielectric properties of $BaTiO_3$, $CoFe_2O_4$ and $0.5BaTiO_3-0.5CoFe_2O_4$ samples show frequency dependence, which is classified as relaxor behavior with different relaxing degree. The relaxor behaviors were described using the modified Curier-Weiss and Vogel-Fulcher laws. Among three above samples, the $BaTiO_3$ sample has highest relaxing degree. Photoluminescence spectral indicated defects, which might in turn control relaxing degree.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.50.2-50.2
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• 2017

Spatial distribution of atmosphereless bodies in the solar system provides an important clue as to their origins, namely asteroids from Mainbelt or comets from outer solar system. It is, however, difficult to distinguish asteroids and dormant comets due to their similar appearances. In this study, we conducted a unique observation to differentiate asteroids and dormant comets in terms of 'polarimetry'. We observed (331471) 1984 QY1 (hereafter QY1) at large phase angles using the Multi-Spectral Imager (MSI) on the 1.6-m Pirka Telescope from UT 2016 May 25 to June 24. QY1 is a dormant comet candidate in terms of the dynamical properties (i.e. the Tisserand parameter with respect to Jupiter, TJ = 2.68). We analyzed the polarization degree of QY1 as a function of phase angle and found its maximum polarization degree, $Pmax=8.68{\pm}0.28%$ and $8.72{\pm}0.38%$, in RC-and V-band, respectively, around the phase angle of ${\alpha}=100^{\circ}$. In addition, we obtained the geometric albedo, $pV=0.16{\pm}0.02$ by means of an empirical slope-albedo law. The polarimetric properties and the albedo value we acquired are similar to those of S-type asteroids rather than cometary nuclei. In this presentation, we introduce our observation and findings. In addition, we further discuss a dynamical transportation process from Mainbelt to the current orbit.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.44.4-45
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• 2018

(4179) Toutatis (Toutatis hereafter) is one of the Near-Earth Asteroids which has been studied most rigorously not only via ground-based photometric, spectroscopic, polarimetric, and radar observations, but also via the in-situ observation by the Chinese Chang'e-2 spacecraft. However, one of the most fundamental physical properties, the geometric albedo, is less determined. In order to derive the reliable geometric albedo and further study the physical condition on the surface, we made photometric observations of Toutatis near the opposition (i.e., the opposite direction from the Sun). We thus observed it for four days on 2018 April 7-13 using three 1.6-m telescopes, which consist of the Korean Microlensing Telescope Network (KMTNet). Since the asteroid has a long rotational period (5.38 and 7.40 days from Chang'e-2, Zhao et al., 2015), the continuous observations with KMTNet matches the purpose of our photometric study of the asteroid. The observed data cover the phase angle (Sun-asteroid-observer's angle) of 0.65-2.79 degree. As a result, we found that the observed data exhibited the magnitude changes with an amplitude of ~0.8 mag. We calculated the time-variable geometrical cross-section using the radar shape model (Hudson & Ostro 1995), and corrected the effect from the observed data to derive the geometric albedo. In this presentation, we will present our photometric results. In addition, we will discuss about the regolith particles size together with the polarimetric properties based on the laboratory measurements of albedo-polarization maximum.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.45.2-46
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• 2021

The Hayabusa 2 mission target asteroid (162173) Ryugu is a near-Earth, carbonaceous (C-type) asteroid. Before the arrival, this asteroid is expected to be covered with mm- to cm- sized grains through the thermal infrared observations [1]. These grains are widely understood to be formed by past impacts with other celestial bodies and fractures induced by thermal fatigue [2]. However, the close-up images by the MASCOT lander showed lumpy boulders but no abundant fine grains [3]. Morota et al. suggested that there would be submillimeter particles on the top of these boulders but not resolved by Hayabusa 2's onboard instruments [4]. Hence, we conducted polarimetry of Ryugu to investigate microscopic grain sizes on its surface. Polarimetry is a powerful tool to estimate physical properties such as albedo and grain size. Especially, it is known that the maximum polarization degree (Pmax) and the geometric albedo (pV) show an empirical relationship depending on surface grain sizes [5]. We observed Ryugu from UT 2020 November 30 to December 10 at large phase angles (ranging from 78.5 to 89.7 degrees) to derive Pmax. We modified TRIPOL (Triple Range Imager and POLarimeter, [6]) to attach to the 1.8-m telescope at the Bohyunsan Optical Astronomy Observatory (BOAO). With this instrument, we observed the asteroid and determined linear polarization degrees at the Rc-band filter. We obtained sufficient data sets from 7 nights at this observatory to determine the Pmax value, and collaborated with other observatories in Japan (i.e., Hokkaido University, Higashi-Hiroshima, and Nishi-Harima) to acquire linear polarization degrees of the asteroid from total 24 nights observations with large phase angle coverage (From 28 to 104 degrees). The observational results have been published in Kuroda et al. (2021) [7]. We thus found the dominance of submillimeter particles on the surface of Ryugu from the comparison with other meteorite samples from the campaign observation. In this presentation, we report our activity to modify the TRIPOL for the 1.8-m telescope and the polarimetric performance. We also examine the rotational variability of the polarization degree using the TRIPOL data.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.45.1-45.1
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• 2021

The polarization degree as a function of phase angle (the Sun-target-observer's angle), so-called the polarimetric phase curves (PPC), have provided priceless information on asteroids' albedos since B. Lyot (1929). Succeeding experimental works in 1970s have confirmed the Umow law: There is a universal and strong correlation between the albedo and the PPC slope (slope of the tangential line at the zero of the PPC at phase angle ~ 20 degrees). Experiments in 1990s (ref [1]), on the other hand, have demonstrated that the negative branch of PPC is dependent on the size parameter (X ~ π * particle-size / wavelength), especially when X <~5. The change in particle size changed the minimum polarization degree, location of the minimum, and the width of the negative branch (called the inversion angle). From polarimetry[2] and spectroscopy[3], large asteroids are expected to be covered with fine (<~ 10 ㎛ size) particles due to the gravity. The size parameters are X ~ 30 at the optical wavelength (λ ~ 0.5 ㎛) and X ~ 10 in near-infrared (J, H, Ks bands; λ ~ 1.2-2.2 ㎛), if the representative particle size of 5 ㎛ is considered. Accordingly, the near-infrared polarimetry has a great potential to validate the idea in ref[1]. We conducted near-infrared photopolarimetry of the large asteroid (4) Vesta using the Nishiharima Infrared Camera (NIC) at Nishi-Harima Astronomical Observatory (NHAO). NIC allows simultaneous polarimetric measurements in J, H, and Ks bands, and thus the change of PPC is obtained for three different size parameters. As a result, we found a signature of the change in the negative branch in the PPC of asteroid (4) Vesta. We will introduce our observation and the results and give an interpretation of the regolith on Vesta.

• Journal of Oriental Neuropsychiatry
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• v.8 no.2
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• pp.1-12
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• 1997

As there has recently been growing interest in Alternative Medicine, Oriental Medicals have been trying to incorporate Alternative Medicine into Oriental Medicine evolutionarily. The purpose of this study is to make a comparative study of the historical background and present condition, the view of life, the principle of therapeutics, and the various therapeutics in Alterative Medicine and Oriental Medicine from the viewpoint of Oriental Medicine. The conclusion of this study is; 1. Although Alternative Medicine has become influential mainly in the effort of finding a solution the limit of western medicine, the clinical effect of Alternative Medicine should be verified continuously. 2. Alternative Medicine includes all of the therapeutics such as Traditional Medicine, Naturopathy, Complementary Medicine and Selective Medicine whose characters are different from Western Medicine and Oriental Medicine can be regarded as a sort of Alternative Medicine. 3. The holistic, systematic view of life of Alternative Medicine, from which viewpoint human considered as a harmonious vital existence, is a sort of recurrence to the view of Hipporcrates. 4. From the viewpoint of Alternative Medicine, a disease is not partial but holistic disorder and is treated by utilizing natural products as a medicine based on the principle that pursues harmonious and balanced psychosomatic function. This principle of therapeutic is the same as Oriental Medicine is based on. 5. Alternative Medicine may be classified largely five category, (1) Eastern Therapy, (2) Manipulative Therapy, (3) Natural Therapy, (4) Active Therapy, (5) Therapy Involving External Powers. 6. Besides Alternative Medicine which is used in clinical treatment, Massage, Homeopathy, Bach Flower remedies, Meditation, and other Music Therapy and Color Therapy is relatively accordant with therapeutics in Oriental Medicine and should be more actively accepted in clinics and improved.

• Journal of Microbiology
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• v.43 no.4
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• pp.319-324
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• 2005

Estuarine sediments are frequently polluted with hydrocarbons from fuel spills and industrial wastes. Polycyclic aromatic hydrocarbons (PAHs) are components of these contaminants that tend to accumulate in the sediment due to their low aqueous solubility, low volatility, and high affinity for particulate matter. The toxic, recalcitrant, mutagenic, and carcinogenic nature of these compounds may require aggressive treatment to remediate polluted sites effectively. In petroleum-contaminated sediments near a petrochemical industry in Gwangyang Bay, Korea, in situ PAH concentrations ranged from 10 to 2,900 ${\mu}g/kg$ dry sediment. To enhance the biodegradation rate of PAHs under anaerobic conditions, sediment samples were amended with biostimulating agents alone or in combination: nitrogen and phosphorus in the form of slow-release fertilizer (SRF), lactate, yeast extract (YE), and Tween 80. When added to the sediment individually, all tested agents enhanced the degradation of PAHs, including naphthalene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo [a] pyrene. Moreover, the combination of SRF, Tween 80, and lactate increased the PAH degradation rate 1.2-8.2 times above that of untreated sediment (0.01-10 ${\mu}g$ PAH/ kg dry sediment/day). Our results indicated that in situ contaminant PAHs in anoxic sediment, including high molecular weight PAHs, were degraded biologically and that the addition of stimulators increased the biodegradation potential of the intrinsic microbial populations. Our results will contribute to the development of new strategies for in situ treatment of PAH-contaminated anoxic sediments.

• Research in Plant Disease
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• v.10 no.1
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• pp.69-72
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• 2004

The control activity of isoprothiolane and tricyclazole mixed with carbosulfan, and probenazole by the nursery treatment was performed against rice leaf and neck blast caused by Magnaporthe grisea. In the paddy field, three fungicides showed good activities against leaf blast 3 months after nursery treatment. Especially the activity of tricyclazole against leaf blast gradually increased by the laps of time to 85.5％, which was assessed at 6 September,2003. Although the control value of isoprotholane and tricyclazole mixed with carbosulfan against neck blast was 47.5％ and 61.1％, respectively, probenazole showed a very high activity against not only leaf blast but also neck blast, of which that was 91.2％. No phytotoxicity was observed in all the treatments after transplanting rice seedling in the paddy field. Based on these results, three systemic fungicides tested in this study showed such a good potential that they might be used to formulate the nursery treating granule.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.1
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• pp.62-70
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• 1984

N+NPP+ HLEBSF (high low emitter back surface field) solar cells which have N+N high low junction in the emitter as well as N+PP+ BSF cells were designed and fabricated by using <111> oriented P type Si wafers with the resistivity of 10$\Omega$/$\textrm{cm}^2$ and the thickness of 13-15 mil. Physical parameters (impurity concentration, thickness) at each region of N+PP+ and N+NPP+ cell were made equally through same masks and simultaneous process except N region of HLEBSF cell to investigate the high low emitter junction effect for efficiency improvement. Under the light intensity of 100 mW/$\textrm{cm}^2$, total area (active area) conversion efficiency were typically 10.94% (12.16%) for N+PP+ BSF cells and 12.07% (13.41%) for N+N PP+ cells. Efficiency improvement of N+NPP+ cell which has high low emitter Junction structure is resulted from the suppression of emitter recombination current and the increasement of open circuit voltage (Voc) and short circuit current (Ish) by removing heavy doping effects occurring in N+ emitter region.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.2
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• pp.238-245
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• 2009

Pure culture experiments were conducted to assess the bacteriostatic and bactericidal effects of phlorotannins (PT) isolated from Ascophyllum nodosum (brown seaweed) on Escherichia coli O157:H7. In Exp. 1, one non-O157:H7 strain (25922) and three strains of E. coli O157:H7 (3081, EDL933 and E318N) were cultured in M9 medium with PT included at 0 (control), 25, 50 or $100{\mu}g/ml$ (n = 3). Bacterial growth was monitored by $OD_{600}$ at 0, 4, 6, 12 and 24 h, and by dilution plating at 0, 4, 6 and 24 h. All strains were inhibited (p<0.001) by PT to varying degrees. At 50 or $100{\mu}g/ml$, PT prevented growth of all four strains. At $25{\mu}g\;PT/ml$, growth of 25922, 3081, E318N and EDL933 was inhibited for 6, 12 and 24 h, respectively, but 25922 and 3081 resumed growth by 12 and 24 h. Direct plating confirmed bactericidal effects of PT on all four strains at $100{\mu}g/ml$, and on EDL933 and E318N at $50{\mu}g/ml$. In Exp. 2, strains 25922 and 3081 were incubated with no tannins or with $50{\mu}g/ml$ of PT, purified condensed tannins (CT) from Quebracho (Schinopsis balansaei), or purified tannic acid from Rhus semialata (Anacardiaceae) as hydrolysable tannins (HT). Strain 3081 was unaffected by HT or CT, but was completely inhibited (p<0.001) by PT at 4, 6 and 24 h. Strain 25922 was unaffected by HT, slightly inhibited by CT, and almost eradicated by PT at 4 and 6 h. Transmission electron microscopy revealed tannin-mediated alterations to bacterial cell walls. Phlorotannins from A. nodosum exhibit growth-inhibiting and bactericidal effects in vitro against the strains of E. coli O157:H7 investigated. Anti-E. coli efficacy of A. nodosum PT is superior to that of terrestrial tannins purified from Quebracho and from Rhus semialata.