• Journal of Korean Society for Atmospheric Environment
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• v.34 no.2
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• pp.207-222
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• 2018

In this study, light absorption of carbonaceous species in $PM_{2.5}$ was investigated using a dual-spot 7-wavelength Aethalometer(model AE33) with 1-min time interval between January 01 and September 30, 2017 at an urban site of Gwangju. During the study period, two Asian dust (AD) events occurred in April (AD I) and May (AD II), respectively, during which light absorption in total suspended particles was observed. Black carbon (BC) was the dominant light absorbing aerosol component at all wavelengths over the study period. Light absorption coefficients by aerosol particles were found to have 2.7~3.3 times higher at 370 nm than at 880 nm. This would be attributed to light absorbing organic aerosols, which is called brown carbon (BrC), as well as BC as absorbing agents of aerosol particles. Monthly average absorption ${{\AA}}ngstr{\ddot{o}}m$ exponent ($AAE_{370-950nm}$) calculated over wavelength range of 370~950 nm ranged from 1.10 to 1.35, which was lower than the $AAE_{370-520nm}$ values ranging from 1.19~1.68 that was enhanced due to the presence of BrC. The estimated $AAE_{370-660nm}$ of BrC ranged from 2.2 to 7.5 with an average of 4.22, which was fairly consistent to the values reported by previous studies. The BrC absorption at 370 nm contributed 10.4~28.4% to the total aerosol absorption, with higher contribution in winter and spring and lower in summer. Average $PM_{10}$ and $PM_{2.5}$ concentrations were $108{\pm}36$ and $24{\pm}14{\mu}g/m^3$ during AD I, respectively, and $164{\pm}66$ and $43{\pm}26{\mu}g/m^3$ during AD II, respectively, implying the greater contribution of local pollution and/or regional pollution to $PM_{2.5}$ during the AD II. BC concentration and aerosol light absorption at 370 nm were relatively high in AD II, compared to those in AD I. Strong spectral dependence of aerosol light absorption was clearly found during the two AD events. $AAE_{370-660nm}$ of both light absorbing organic aerosols and dust particles during the AD I and II was $4.8{\pm}0.5$ and $6.2{\pm}0.7$, respectively. Higher AAE value during the AD II could be attributed to mixed enhanced urban pollution and dust aerosols. Absorption contribution by the light absorbing organic and dust aerosols estimated at 370 nm to the total light absorption was approximately 19% before and after the AD events, but it increased to 32.9~35.0% during the AD events. In conclusion, results from this study support enhancement of the aerosol light absorption due to Asian dust particles observed at the site.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.231-240
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• 2005

The number of cases exceeding environmental standards of atmospheric ozone in the major cities in Korea has steadily increased during the past decades. In order to understand and analyze the atmospheric reactions in the atmosphere, especially the secondary photochemical reactions, smog chambers studies have been performed very actively by many research groups worldwide. However, these studies have focused on the mechanism of photochemical reactions in high concentration conditions, not at the ambient levels. Therefore, in-depth studies in these conditions are essentially needed to realize exact mechanism in the atmosphere near the earth surface, especially at Korean atmospheric conditions. In this experiment, the mechanism of photochemical smog was examined through a comparative experiment of smog chambers under sun light and black light conditions. The results of our study indicated that concentrations of ozone, aldehyde, and PAN increased as the radiation of light source increases. Photochemical reaction patterns can be considered quite similar for both black light and sun light experiments. Based on our experiments using toluene as a reactant which is present at significant high levels in ambient air relative to other VOCs, it was found that toluene could contribute notably to oxidize NO to $NO_2$, this reaction can eventually generate some other photochemical oxidants such as ozone, aldehyde, and PAN. The results of simulation and experiments generally showed a good agreement quite well except for the case of $O_3$. The restriction of oxidization of NO to $NO_2$ seems to cause this difference, which is mainly from the reaction of peroxy radical itself and other reactants in the real gas.

• Journal of Applied Biological Chemistry
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• v.59 no.2
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• pp.129-132
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• 2016

This study was conducted to evaluate the attraction effects of Sitophilus zeamais and Tribolium castaneum to light emitting diode (LED) trap in granary and compared with the black light bulb (BLB) trap, which is typical used in commercial trap. The red LED trap showed more attractive to S. zeamais and T. castaneum than that of the BLB. Moreover, the external condition of granary was about 1.5 times more attractive to S. zeamais and T. castaneum than the internal condition of granary. These results suggested that red LED trap could be useful to control S. zeamais and T. castaneum in granary.

• Korean journal of food and cookery science
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• v.19 no.1
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• pp.72-78
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• 2003

This study was conducted to investigate the physicochemical and organoleptic characteristics and freshness of wild and cultivated Paralichthys olivaceus during storage. By the results of morphological observation, wild Paralichthys olivaceus had white abdomen, light black skin and transparent muscle, but cultivated Paralichthys olivaceus had black spotted abdomen, dark black skin and dark pink muscle. Moisture contents of wild and cultivated Paralichthys olivaceus were similar, but the lipid content was higher in cultivated Paralichthys olivaceus than that of wild Paralichthys olivaceus. Sensory scores of appearance, taste, texture and overall acceptability were higher in wild Paralichthys olivaceus than that of cultivated Paralichthys olivaceus. The reason was that lipid content was higher in cultivated Paralichthys olivaceus The freshness of cultivated Paralichthys olivaceus seemed to last shorter than that of wild one due to rapid increase of the volatile basic nitrogen content, pH and total microbial count during storage.

• Journal of The Korean Astronomical Society
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• v.23 no.1
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• pp.63-70
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• 1990

The original axisymmetric, stationary electrodynamic model of the central engine in an active galactic nucleus proposed by Macdonald and Thorne consists of a supermassive black hole with magnetic field lines that pass through the region just outside the event horizon of the black hole. Each magnetic field line rotates with a constant angular velocity which will exceed the speed of light at large radii. Even though the field lines are purely mathematical entities this condition sets a stringent physical constraint on the motion of the magnetic field lines and the particles on them. In this paper we will show that we can remove this auxiliary constraint in our model by allowing nonstationary processes. As a result the magnetic field lines can be twisted and wound up in a region lying outside of the quasi-stationary magnetosphere of the black hole. We conclude that astrophysical jets are formed in that region due to the twisted and wound magnetic field lines powered by the Blandford-Znajek process and the other driving forces.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.31.3-31.3
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• 2016

Exploring a universe with gravitational waves (GWs) was only theoretical expectation for long time. In September 2015, the Laser Interferometer GW Observatory (LIGO) first detected GWs emitted from the collision of two stellar-mass black holes in cosmological distance (1.3 billion light years) on Earth. This confirms the existence of black-hole binary mergers, and further, opens a new field of GW astronomy. We begin our discussion with a list of important GW sources that can be detectable on Earth by large-scale laser interferometers such as LIGO. Focusing on compact objects such as neutron stars and black holes, we then discuss possible research in the context of GW astronomy. By coordinating with existing observatories, searching for electromagnetic waves or particles from astronomical objects, around the world, multi-messenger astronomy for the universe's most cataclysmic phenomena (e.g. gamma-ray bursts) will be available in the near future.

• Applied Microscopy
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• v.28 no.4
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• pp.503-512
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• 1998

Fine structure of the cutaneous pigments in the black widow spider, Latrodectus mactans are studied with light and electron microscopes. The cutaneous pigments are only observed in epidermal layer just beneath the cuticle. These pigments are compactly distributed around the spinnerets which located at caudal area of the abdomen. According to the fine structural characteristics of the pigment granules, two main types of guanine pigment granules-carotenoid vesicles and reflecting platelets - are observed in the cytoplasm of the epidermal cells. Morphological features of these pigment granules are characterized as the electron dense carotenoid vesicles and the electron lucent reflecting platelets. Marginal electron density of the carotenoid vesicle is different from that of internal region, whereas the reflecting platelets have laminated crystalline granules. Typiral structures of these pigment granules are very similar to those of invertebrate's chromatophores, especially erythrophores and iridophores. Moreover differentiation of these pigment granules are also originated from the small vesicles of Golgi complexes similarly to those of cutaneous chromatophores.

• Food Science and Preservation
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• v.14 no.4
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• pp.400-407
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• 2007

This study compared lipid oxidation and color stability of M. longissimus from five Korean native black barrows (66 kg average weight; KNP) and modern genotype barrows ($Landrace{\times}Yorkshire{\times}Duroc$, 112 kg average weight, MGP) during light exposure in a refrigerated shop display. The meat samples were aged at $1^{\circ}C$ for 5 days and either kept in the dark, or under light of flux 3,000 lux, at $4^{\circ}C$ for 7 days. The KNPs contained larger amounts of fat than did MGPs (p<0.05), but KNPs had lower $C_{14:0},\;Cl_{8:3},\;and\;C_{20:5}$ contents than did MGPs (p<0.05). The pH of KNP was lower than that of MGP, and increased more rapidly upon exposure to light. The TBARS assay showed that oxidized lipid levels increased more rapidly in KNP than in MGP, and this accumulation was accelerated by exposure to light. The KNP was always a darker red in color than was MGP, and the color deteriorated more rapidly in the light than in the dark. The sensory attributes of raw pork were reduced by exposure to light, but KNP showed higher sensory attributes than did MGP. Compared to the MGP, the KNP showed greater color stability under light, retained desired sensory attributes under light longer, but showed a lower lipid oxidation stability under light. Overall, light exposure accelerated lipid oxidation in and discoloration of pork.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.113-116
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• 2006

This study was carried out to investigate spectral irradiance characteristics of blue, yellow, and blue-black colored polyethylene (PE) shading net and the effect on growth characteristics and yield in ginseng seedling. The spectral irradiance $({\mu}mol/m^2/s/nm)$ showed the peak at 498 nm in both of blue and blue-black PE shading net, and 606 nm under yellow PE one. The intensity of blue light in blue shading was more strong than that of blue-black shading, control. Blue shading was increased by 17% and 23% in accumulated quantum for daytime, $0.5^{\circ}C and $0.2^{\circ}C$ in maximum temperature on June 2 than that of yellow and blue-black shading, respectively, but heat injury ratio of the former was lower than that of the latter. Chlorophyll content and stem length in blue shading were decreased more significantly than those of yellow and blue-black shading. The specific leaf weight was higher under blue and yellow shading than that of blue-black shading. Ginseng seedling harvested in blue shading was increased by $13{\sim}17%$ in the number of root, and $17{\sim}20%$ in root weight per $m^ 2 compared to yellow and blue-black shading owing to the increase of survived plant, and the decrease of specific leaf weight, heat injury ratio, and stem length.

• Current Research on Agriculture and Life Sciences
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• v.27
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• pp.13-19
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• 2009

The purpose of this study was the efficient use of the black rice bran for dyeing textiles. For this purpose, we investigated proper extracting conditions of black rice bran, dyeability and dyeing fastness of dyed silk fabrics. To find proper extracting condition of black rice bran, we extracted black rice bran with water at different temperatures($40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$), different extracting pH(pH3, pH4, pH5, pH6) and extracting time(20, 40, 60, 80, 100, 120, 140, 160, 180min.). Also we investigated the effect of dyeing time(1, 2, 3, 4, 5, 6hr.), dyeing temperature($40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$) and mordanting method(non, pre, sim, post) to examine dyeability and dyeing fastness of dyed silk fabrics. As a result, when the extracting temperature and time were $80^{\circ}C$, 3hr., respectively, extracting was best. And the higher the extracting concentration, the more the extracting amount. As the dyeing temperature and time were higher and longer, the dyeability of silk fabrics was better. With mordant, the dyeability was improved and when using premordant method better, the K/S value was maximized. The laundering fastness of the silk fabrics dyed with black rice bran was estimated to have a good grade of 3~4, however, the light fastness was poor to have a grade of 1~2.