• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.38-43
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• 2018

A few authors have already investigated microbial contamination of leafy vegetables in distribution condition and examined the effect of temperature abuse on microbial safety or product quality. But this study analyzed proliferation of indicator microorganisms and food poisoning bacteria in real situation in Korean agroindustry and investigated washing effect of micobial contamination on leaf surface. Leafy vegetables were found to be contaminated with aerobic bacteria at $0.1{\sim}0.32{\times}10^3CFU/g$. Staphylococcus aureus and Bacillus cereus were detected in leafy vegetables at $0{\sim}0.54{\times}10^3CFU/g$. However, Salmonella spp., Coliforms, Clostridium spp. and Listeria spp. were not detected in any samples. Indicator microorganisms and food poisoning bacteria on leafy vegetables increased at room temperature when simulatively distributed condition. After clean-up, the indicator microorganisms and food poisoning bacteria of kimchi cabbage, lettuce and perilla leaf were decreased to a very low level. This study suggests that it is necessary to improve the level of hygiene management such as use of cold chain system and hygiene management of transport tools during the distribution process for fresh leafy vegetables.

• 한국해양학회지
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• v.26 no.1
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• pp.83-100
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• 1991

A layer of salinity-minimum which characterizes the East Sea intermediate Water (ESIW) is found at an approximate depth of 200 m in three CTD section taken in the Ulleung Basin on May 17-21, 1988. Properties at this layer vary in ranges of $1.1^{\circ}C except at stations near the east coast of Korea where temperature is as high as $4.39^{\circ}C$ and salinity is as low as $33.992{\textperthousand}$. To be distinguished from the ESIW the East Sea Proper Water (ESPW) may be characterized by temperature less than $1^{\circ}C$, Salinity at the saliently-minimum layer and 500db increases southward in general, implying that the cold waters, both ESIW and ESPW, formed in the northern basin of the East Sea are spreading southward below the permanent thermocline in the basin. Hydrography in the Ulleung Basin is very similar to that in the Alboran Sea, suggesting a possibility of an anticyclonic circulation in the Ulleung Basin which is controlled strongly by the shoaling bottom.

• Applied Biological Chemistry
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• v.38 no.1
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• pp.42-48
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• 1995

The experiment was carried out to purify and to investigate the properties of the cyclodextrinase produced from Bacillus megaterium KFCC 11855. The enzyme was partially purified with $(NH_4)_2SO_4$ and chromatography on DEAE-trisacryl, Ultrogel AcA 34, DEAE-trisacryl and Ultrogel HA. The optimum temperature and pH of the purified enzyme were $60^{\circ}C$ and 6.0, respectively. The enzyme was stable at the temperature of $45^{\circ}C$ below and at the pH range of $6.0{\sim}9.0$, respectively. The Km value for ${\gamma}-cyclodextrin$ was 0.903 mM. The enzyme activity was increased by $Mg^{2+}$ and $Mn^{2+}$, but decreased by $Hg^{2+}$ and $Cu^{2+}$. The enzyme degraded ${\gamma}-cyclodextrin$ but not ${\alpha}-cyclodextrin$. The degree of ${\beta}-CD$ degradation by the enzyme was very low. The decomposed products of ${\gamma}-cyclodextrin$ by the enzyme were mainly glucose, maltose and a little amount of maltotriose.

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.423-441
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• 2013

On 21 September 2010, one of Chuseok holidays in Korea, localized heavy rainfalls occurred over the midwestern region of the Korean peninsula. In this study MTSAT-2 infrared and water vapor channel imagery are examined to find out some features which are obvious in each stage of the life cycle of convective cell for this heavy rain event. Also the kinematic and thermodynamic features probably associated with them are investigated. The first clouds related with the Chuseok heavy rain are detected as low-level multicell cloud (brightness temperature: $-15{\sim}0^{\circ}C$) in the middle of the Yellow sea at 1630~1900 UTC on 20 Sept., which are probably associated with the convergence at 1000 hPa. Convective cells are initiated in the vicinity of Shantung peninsula at 1933 UTC 20, which have developed around the edge of the dark region in water vapor images. At two times of 0033 and 0433 UTC 21 the merging of two convective cells happens near midwestern coast of the peninsula and then they have developed rapidly. From 0430 to 1000 UTC 21, key features of convective cell include repeated formation of secondary cell, slow horizontal cloud motion, persistence of lower brightness temperature ($-75{\sim}-65^{\circ}C$), and relatively small cloud size (${\leq}-50^{\circ}C$) of about $30,000km^2$. Radar analysis showed that this heavy rain is featured by a narrow line-shaped rainband with locally heavy rainrate (${\geq}50$ mm/hr), which is located in the south-western edge of the convective cell. However there are no distinct features in the associated synoptic-scale dynamic forcing. After 1000 UTC 21 the convective cell grows up quickly in cloud size and then is dissipated. These satellite features may be employed for very short range forecast and nowcasting of mesoscale heavy rain system.

• Korean Journal of Plant Resources
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• v.33 no.1
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• pp.33-39
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• 2020

This study was carried out to provide basic information for mass breeding and cultivating the saplings of Camellia japonica. The germination rates did not show definite tendency according to the changes of seed weight at room temperature and 4℃ dry storage conditions. The germination rate of 4℃ wet sand storage was increased with seed weight, but showed very low germination rate for 120 days of storage. The germination rate was above 80% in 60 days, 90 days and 120 days, respectively, at 4℃ wet filter paper storage conditions. The average days taken for those germinations were about 30 days at room temperature and 4℃ dry storage conditions, but wet storage (sand, filter paper) condition took the shortly nearly 13 days for those germinations. Leaf number, leaf dry weight, stem diameter and root dry weight were higher than total average by more than 1.21 g for seed weight. Stem length was higher than the average by more than 1.01 g, plant dry weight was higher than the average by more than 0.81 g, and stem dry weight was higher than the average by more than 0.61 g. In the case of seed weight becoming heavier, seedling growth was good but T/R ratio tended to decrease. In order to increase the mass production of seedlings using Camellia japonica seeds, we need to specify the weight and size of those seeds. The 4℃ wet filter paper storage condition was evaluated as the most efficient method for the seed storage used for seeding.

• Korean Journal of Medicinal Crop Science
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• v.13 no.4
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• pp.171-177
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• 2005

This study was carried out to investigate the distribution and habitat feature of Glehnia littoralis as a part of establishment of conservation plan for important natural agro-plant resources in South Korea. Habitat of Glehnia littoralis was generally found 28.2 m from high tide water line and 2.7 m above sea level at sand dunes near three seashore areas. Density and coverage of Glehnia littoralis were higher in east seashore among three seashore areas. The number of plant species growing with Glehnia littoralis in natural habitat was found 35 species. Among 35 species Ixeris repens Carex pumila, Carex kobomugi, Elymus mollis, Ischaemum anthephoroides, Imperata cylindrica var. koenigii were shown higher density and coverage. Average yearly precipitation and temperature of habitat for Glehnia littoralis were 1250.3 mm and $12.5^{\circ}C$, respectively. Among three seashores, the precipitation and temperature of south seashore were much more and higher than those of other two seashores. Soil characteristics of habitat for Glehnia littoralis were that average pH was 7.9 and organic matter was 0.23%. Content $P_2O_5$ and Ca were relatively higher, but the level K and Na were very low.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.553-566
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• 2015

The effects of vertical resolutions and planetary boundary layer (PBL) physics schemes in a numerical simulation with a very high resolution over the metropolitan area were investigated. The numerical experiments using the Weather Research and Forecast model were conducted from 0000 UTC 25 October to 0000 UTC 26 October 2013. We verified the numerical results against with six hourly observation data from the radiosonde at Seolleung, which was located in southern part of Seoul, and forty three auto weather systems in Seoul. In the experiments of vertical resolutions in low level atmosphere with 44, 50, and 60 layers, which are set to be subdivided particularly under 2 km height. The experiment in 60 layers, which has the highest vertical resolution in this study, showed relatively a clear diurnal variation of PBL heights. Especially, the difference of PBL heights and 10-meter wind fields were mainly seen in the area of high altitude lands for the experiments of vertical resolution. In the sensitivity experiment of PBL schemes such as asymmetric convective model-version 2 (ACM2), Yonsei University (YSU), and Mellow-Yamada-Janjic (MYJ) to the temperature, all three PBL schemes revealed lower temperature than observed profile from the radiosonde in the entire period. The experiments with YSU PBL and ACM2 PBL schemes show relatively less biased in comparison with the experiment of the MYJ PBL scheme.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.11-11
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• 2008

ZnO has a very large exciton binding energy (60 meV) as well as thermal and chemical stability, which are expected to allow efficient excitonic emission, even at room temperature. ZnO based electronic devices have attracted increasing interest as the backplanes for applications in the next-generation displays, such as active-matrix liquid crystal displays (AMLCDs) and active-matrix organic light emitting diodes (AMOLEDs), and in solid state lighting systems as a substitution for GaN based light emitting diodes (LEDs). Most of these electronic devices employ the electrical behavior of n-type semiconducting active oxides due to the difficulty in obtaining a p-type film with long-term stability and high performance. p-type ZnO films can be produced by substituting group V elements (N, P, and As) for the O sites or group I elements (Li, Na, and K) for Zn sites. However, the achievement of p-type ZnO is a difficult task due to self-compensation induced from intrinsic donor defects, such as O vacancies (Vo) and Zn interstitials ($Zn_i$), or an unintentional extrinsic donor such as H. Phosphorus (P) doped ZnO thin films were grown on c-sapphire substrates by radio frequency magnetron sputtering with various Ar/ $O_2$ gas ratios. Control of the electrical types in the P-doped ZnO films was achieved by varying the gas ratio with out post-annealing. The P-doped ZnO films grown at a Ar/ $O_2$ ratio of 3/1 showed p-type conductivity with a hole concentration and hole mobility of $10^{-17}cm^{-3}$ and $2.5cm^2/V{\cdot}s$, respectively. X-ray diffraction showed that the ZnO (0002) peak shifted to lower angle due to the positioning of $p^{3-}$ ions with a smaller ionic radius in the $O^{2-}$ sites. This indicates that a p-type mechanism was due to the substitutional Po. The low-temperature photoluminescence of the p-type ZnO films showed p-type related neutral acceptor-bound exciton emission. The p-ZnO/n-Si heterojunction LEO showed typical rectification behavior, which confirmed the p-type characteristics of the ZnO films in the as-deposited status, despite the deep-level related electroluminescence emission.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.191-198
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• 2010

This research was performed to investigate the effect of hydrogen peroxide on the stain removal in japanese hackberry. Response surface method (RSM) was used to optimize the bleaching conditions such as reaction temperature, reaction time and the concentration of hydrogen peroxide. Fifteen different bleaching conditions were selected according to $2^3$ factorial central composite design (CCD). The bleaching effect were evaluated by lightness differences of wood surface before and after the bleaching. The RSM model was determined and its $R^2$ values were 0.93, showing it well represented the bleaching effect. The most affecting factor on the stain removal was the concentration of hydrogen peroxide, followed by reaction time and reaction temperature. Second degree of concentration was proved to have an effect on the bleaching. Bleaching rates above 3% concentrations of hydrogen peroxide were tended to be slightly decreased, and low bleaching effect was found at $20^{\circ}C$. The determined RSM model may offer very practical ways to obtain the desired levels of bleaching because it offers multiple solutions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.95-100
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• 2006

Synthesis of the non-swelling property micas was carried out by hydrothermal method. In order to artificially induce the diffusion of ions, a rotating system was attached to the hydrothermal apparatus and by adding 0.7 mm zircon beads, synthesis of the non-swelling property micas could be performed in a low temperature area. The hydrothermal conditions for the preparation of micas were a reaction temperature of $260^{\circ}C$, for 72 hrs, using $1K_2O,\;1Al(OH)_3,\;4Mg(OH)_2\;and\;6SiO_2$ as the starting materials and a 8M-KOH solution as the hydrothermal solvent. The micas obtained under these conditions were a plate shape with a size of $2.89{\mu}m$ and showed a whiteness of over 97 %. Also, through the FT-IR analysis, because the absorption peak of the $Mg_3OH$ vibration was observed at approximately $3700cm^{-1}$, it could be known that it was phlogopite of non-swelling property showing the chemical composition of $KMg_3AlSi_3O_{10}(OH)_2$. This result was very consistent with the EDS analysis where O (41.34 %), Mg (3.88 %), Al (11.45 %), Si (17.62 %) and K (25.71%) elements were detected.