• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.271-277
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• 2012

The present study was conducted to assess the suitability of domestic natural waters as a Daphnia magna culture medium. In order to assess survival rate and reproductive output, young female daphnids (parent animals), aged less than 24 hours at the start of the test and produced in the Elendt M4 medium, were exposed to Elendt M4 medium, de-chlorinated tap water, and natural mineral water for 21 days. D. magna cultured in Elendt M4 medium (reference medium) and natural mineral water met the criteria of OECD No. 211, Daphnia magna Reproduction Test Guidelines in terms of percent adult survival, first day of reproduction, and average young production. However, the mortalities of adult daphnids observed in de-chlorinated tap water were more than 20% in two reproduction tests for 21 days. Mortality was observed on exposure days 13, 15, and 18 in de-chlorinated water. The use of D. magna is recommended in water of hardness >80 mg $CaCO_3\;L^{-1}$. However, the hardness of de-chlorinated tap water used in the present study was 50~53 mg $CaCO_3\;L^{-1}$. Therefore, it is judged that the delayed mortalities observed in de-chlorinated tap water were caused by a rapid decreased in hardness when the medium was changed from Elendt M4 to de-chlorinated tap water. When D. magna is cultured using domestic natural waters (underground water, surface water, and de-chlorinated water), the quality-control (QC) data should be maintained through a standardization for health assessment method, toxicity test method using reference chemical, test intervals of reference toxicant toxicity test, and data treatment and interpretation. In the long term, national research programs are needed for the development of test species which are representative of domestic aquatic environmental conditions among indigenous daphnids.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.459-473
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• 2012

This study evaluated the rainfall-runoff characteristics of Non-point Pollution Source (NPS) of the impervious area through on-site monitoring. In this study, trend analysis was performed by various runoff analysis method of non-point pollution source. The characteristics of rainfall at impervious area appeared to be influenced by rainfall strength. It is judged that the measure is required to be prepared against that now that concentration difference of non-point pollution source appeared to be big by precedent number of days of no rainfall. However, it appeared that Rainfall Sustaining Time (RST) has nothing to do with effluent concentration of non-point pollution source, however, the rising tendency that effluent concentration did not appear because the tendency that concentration of non-point pollution source reduces more than 50% within initial 60 min due to first flushing effects and rainfall sustaining time is long. If looking into the outflow tendency of non-point pollution source at the impervious area, it showed the tendency that the concentration lowers gradually as time goes by after initial concentration appeared very high. However, it could be recognized that the concentration of non-point pollution source appeared to be high as the pollutants integrated on the surface of the road during dry season. The Event Mean Concentrations (EMCs) in impervious area were ranged $9.2{\sim}199.3mg{\cdot}L^{-1}$ for TSS, $8.1{\sim}24.2mg{\cdot}L^{-1}$ for $COD_{Mn}$, $0.070{\sim}1.860mg{\cdot}L^{-1}$ for T-N. Based on such runoff characteristics of non-point pollution source, it is judged that it would be desirable to process initial rain efficiently as the measure against initial rain phenomenon at the impervious area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.1-12
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• 2013

Acoustic backscatter profiles were measured by Eco-sounder along an east-west section in the mid-eastern Yellow Sea and at an anchoring station in the low salinity region off the Keum River estuary in September 2012, with observing physical water property structure by CTD. Tidal front was established around the sand ridge developed in 50 m depth region. Internal waves measured by Eco-sounder during low tide period in the eastern side of the sand ridge were nonlinear depression waves with wave height of 15 m and mean wavelength of 500 m. These waves were interpreted into tidal internal waves that were produced by tidal current flowing over the sand ridge to the southeast. When weakly non-linear soliton model was applied, propagation speed and period of these internal depression wave were 50 m/s and 16~18 min. Red tides by Dinoflagelates Cochlodinium were observed in the sea surface where strong acoustic scattering layer was raised up to 7 m. Hourly CTD profiles taken at the anchoring station off the Keum River estuary showed the halocline depth change by tidal current and land-sea breeze. When tidal current flowed strongly to the northeast during flood period and land-breeze of 7 m/s blew to the west, the halocline was temporally raised up as much as 2 m and acoustic profile images showed a complex structure in the surface layer within 5-m depth: in tens of seconds the declined acoustic structure of strong and weak scattering signals alternatively appeared with entrainment and intrusion shape. These acoustic profile structures in the surface mixed layer were observed for the first time in the coastal sea of the mid-eastern Yellow Sea. The acoustic profile images and turbidity data suggest that relatively transparent low-layer water be intruded or entrained into the turbid upper-layer water by vertical shear between flood current and land breeze-induced surface current.

• Korean Journal of Microbiology
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• v.47 no.2
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• pp.137-142
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• 2011

$TiO_2$-coated bamboo activated carbon has been prepared and utilized under UV irradiation as a pretreatment method for an effective biodegradation of the recalcitrant polyaromatic hydrocarbons (PAHs). The anatase $TiO_2$ was successfully coated on the bamboo activated carbon (AC) and it showed the highest photoactivity against methylene blue. In the absence of the PAHs-degrading bacteria PAHs having low molecular weight (i.e., naphthalene, acenaphthylene, acenaphthene, and fluorene) were degraded by 9.8, 76.2, 74.1, and 40.5%, respectively. Higher molecular weight PAHs, however, maintained high residual concentrations of PAHs (400-1,000 ${\mu}g$/L) after the same treatment. On the other hand, the overall concentrations of PAHs became lower than 340 ${\mu}g$/L when the pretreated PAHs were subjected to biodegradation by a PAH-degrading consortium for a week. Herein, phenanthrene, anthracene, fluoranthene, and pyrene were removed by 29.3, 61.4, 27.0, and 44.3%, respectively, indicating the facilitated potential biodegradation of PAHs. Activated carbon coated with $TiO_2$ appeared to inhibit growth of PAH degraders on the surface of AC, indicating planktonic degraders were dominantly involved in the PAH biodegradation in presence of the $TiO_2$-coated bamboo AC. It was proposed that an effective remediation technology for the recalcitrant PAHs could be developed when an optimum pretreatment process is further established.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.385-390
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• 1998

The effect of agglomeration treatment was examined to prevent the parched cereal powder from clumping when it is blended with water. Parched cereal powder was composed of 66.9% carbohydrate, 7% water, 12.1% crude protein, 12.1% crude fat and 1.9% ash, respectively. Particle size of parched cereal powder was generally enlarged by agglomeration treatment. This phenomenon was confirmed by particle size analyzer and microscopic observation. The color of agglomerated sample was shown to be slightly darker than the untreated sample. The water absorption indices of agglomerated samples which were steamed for 2min and re-dried were significantly increased as compared with the untreated sample. The water solubility indices of agglomerated samples showed generally lower values than those of untreated samples. In views of quality and processing time, the optimum condition of agglomeration treatment for manufacturing well-dispersable parched cereal powder in water was 15min re-drying after 2min steaming. It is concluded that the agglomeration treatment improves the dispersibility of parched cereal powder and thus facilitates the intake of it after mixing with water.

• The korean journal of orthodontics
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• v.31 no.6 s.89
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• pp.601-610
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• 2001

The purpose of this retrospective study was to evaluate the level oi alveolar bone support of the erupted Permanent canine through the reconstructed cleft region compared to the contralateral canine on the non-cleft side. This study was limited to children with complete unilateral cleft lip and palate who underwent secondary alveolar iliac bone gvaft and the apices of the erupted canine roots were closed at the time of evaluation. With these criteria the study included 21 children whose average age at the time of bone graft reconstruction was 9.8 years, with a minimum of 12.4 years of age at the time of the evaluation. The study was limited to the use of iliac cancellous bone as the autograft material for reconstruction of the alveolar cleft. Cranial bone graft and other autogenous bone sources were excluded. The periapical radiographs were used to evaluate alveolar bone level of each canine. The percentages of root supported by the bone were established by dividing the amount of root covered with the bone by the anatomic root length. The canine oi the non-cleft side was used as an internal control and the canine on the cleft side was used as an experimental. There was a statistically significant difference in the alveolar bone support ratio between the control ($92.9\%$) and experimental canines ($8.7\%$). An average of $95\%$ level of alveolar bone support was achieved for the experimental canine in comparison to the control canine. Neither the presence of lateral incisor, nor the stage of root development of the canine at the time of the bone graft appeared to have affected the alveolar bone support ratio of the canine after the secondary bone graft.

• Membrane Journal
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• v.21 no.2
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• pp.118-126
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• 2011

A method of light pre-irradiation, one of methods modifying hydrophobic surface to hydrophilic surface in a membrane, was proposed to overcome the drawback of previous methods such as blending, chemical treatment and post-irradiation, Process of membrane preparation in the study was comprised of 4 parts as follows: firstly process of precursor preparation to introduce hydrophilic nature under atmosphere and aqueous vapor by irradiating electron beam (EB), secondly process of dope solution preparation to cast on non-woven fabrics, thirdly process of casting to prepare membrane and finally process of coagulation in non-solvent to form porous structure. The merit of this method might show simple process as well as homogenous modification compared to previous methods. To carry it out, precursor was prepared by irradiating EB to powder PVDF at 75~125 K Gray dose. Precursor prepared was analyzed by FTIR, EDS and DSC to confirm the introduction of hydrophilic function and its mechanism. From their results, it was inferred I conformed that hydrophilic function was hydroxy1 and it was introduced by dehydrozenation. Hydrophilicity of membranes prepared was evaluated by contact angle (pristine PVDF : $62^{\circ}$, 125 K Gray-PVDF$13^{\circ}$). Porosity was evaluated by mercury intrusion method, simultaneously morpholoy and surface pore size were observed by SEM phothographs. The result showed the trend that more dose of EB led to smaller pore size and to lower porosity (pristine PVDF : 82%, 125 K Gray-PVDF : 63%). Trend of water permeability was similar to result above (pristine PVDF : 892 LMH, 125 K Gray-PVDF : 355 LMH).

• Journal of Aquaculture
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• v.13 no.3
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• pp.267-275
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• 2000

To evaluate the characteristics and efficiency of oxygen transfer rate of a polystyrene foam bead as media in a packed column aerator was tested. This media has more surface area and cheaper than other ordinary plastic media. The polystyrene foam media was a sphere-shaped bead with 2.5 mm in diameter and specific surface area was 1,350 $m^2$/$m^3$. Oxygen transfer rate and standard aeration efficiency were tested under different hydraulic loading rates, depths of the media and temperatures. Experiment 1 was performed using a small packed column aerator with 10 cm in diameter and 1 m in length. The aerator filled with 0, 4.5, 9.0 and 18.0 cm of the media was tested under hydraulic loading rates of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperatures of 20, 25 and 3$0^{\circ}C$, respectively. In this experiment, standard oxygen transfer rate (SOTR) increased with the hydraulic loading rate and depth of the media increased. The maximum SOTR was reached at 5.6 $m^3$/$m^2$/min of hydraulic loading rate with 9 cm in depth of the media. However, standard aeration efficiency (SAE) decreased with the hydraulic loading rate increased because electricity consumed by pump increased as hydraulic loading rate increased. The highest SAE was reached at hydraulic loading rate of 2.0 $m^3$/$m^2$/min with 9.0 cm in depth of the media. Therefore, the highest SOTR and SAE were achieved at 9.0 cm in depth of the media regardless of the hydraulic loading rate. The maximum SAE was about 1.8 kg $O_2$/kW-hr with the hydraulic loading .ate of $m^3$/$m^2$/min at temperature of 20 $^{\circ}C$.Experiment 2 was performed using a larger aerator, 20 cm in diameter with 2 m in height. The aerator filled with 0, 9, 18, 27 and 36 cm of the media was operated under hydraulic loading rate of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperature of 27 $^{\circ}C$. The SAE reached to the highest efficiency (1.9 kg $O_2$/kW-hr) at 2.0 $m^3$/$m^2$/min of hydraulic loading rate and 36 cm in depth of the media. According to the above results, the polystyrene foam bead as a media in a packed column aerator was effective to increase oxygen transfer rate.

• The Korean Journal of Mycology
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• v.30 no.2
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• pp.86-94
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• 2002

Recently a serious outbreak of weed mould caused by a species of Hypocrea occurred in oyster mushroom (Pleurotus ostreatus) substrates in Korea. The disease was characterized by a rapid infestation of the oyster mushroom substrates by Hypocrea sp. and subsequent inhibition of fructification of the mushroom. In spite of it's serious losses to the oyster mushroom industry in Korea, etiology and ecology of the disease have not been studied. Morphological characteristics of the fungus were examined and molecular characteristics of the fungus were compared with those of the green moulds (Trichoderma spp.) isolated from oyster mushroom bed. Stromata formed superficially on suface of the substrates were pulvinate to effuse or irreguler, initially white but becoming yellowish brown, measuring $6.0{\sim}13.0{\times}3.0{\sim}11.0mm$. Perithecia were globose to subglobose, immersed in stroma, $223{\sim}263\;(Ave.239.9){\times}167.3{\sim}231\;(Ave.204.1){\mu}m$ in size. Asci were unitunicate, cylindrical, nonamyloid, $82.7{\sim}124.8\;(Ave.103.3){\times}4.1{\sim}5.1\;(Ave.4.9){\mu}m$ in size, 16 part-spored. Ascospores were bullet-shaped or somewhat oblong, hyaline, bicellular, roughened or warted, $5.4{\sim}7.4\;(Ave.6.5){\times}3.6{\sim}5.5\;(Ave.4.7){\mu}m$ in size. This fungus readily form the stroma on PDA. Mycelia on PDA nearly invisible and without cottony aerial mycelium. Optimum temperature for mycelial growth of this fungus was $25^{\circ}C$ on PDA and its growth rate was 15 mm per day. This species did not grow at below 10 and above $35^{\circ}C$. Phialides in culture enlarged in the middle and aggregated to penicillate type. They were very variable, shorted ampulliform and occasionally curved when matured, but cylinderical when young, measuring $11.9{\sim}24.3\;(Ave.\;14.7){\times}2.9{\sim}3.9\;(Ave.\;3.4){\mu}m$ when matured and $7.2{\sim}14.0\;(Ave.\;10.8){\times}2.8{\sim}4.9\;(Ave.\;3.5){\mu}m$ when young. Phialosopres were ovoid to ellipsoid, smooth, measuring $3.5{\sim}7.2\;(Ave.\;4.5){\times}2.6{\sim}3.3\;(Ave.\;2.9){\mu}m$. Nineteen isolates of Hypocrea sp. were analyzed on the basis of molecular characteristics and classified into phenotypic groups. On the basis of RAPD, URP-PCR, the fungus was confirm to monoclonal, and was classified as a different taxon from reported species of Hypocrea and Trichoderma and supposed to be a new species not previously reported in literature.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.62-79
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• 1994

The quanttative and structural analysis of the binary standard mixtures of albite and quartz, and microcline and albite were carried out using the Rietveld refinement method in order to investigate the accuracy and precision of the method. The quantitative analysis using the Rietveld method results in a standard deviation of 4 wt % for the albite-quartz standard mixtures and 1 wt % for the microcline-albite standard mixtures, suggesting that its accuracy is far better than that of the conventional XRD method in which only a few selected peaks are utilized. Furthermore, the unit-cell parameters of component minerals in mixtures were also estimated accurately during the analysis. It was observed that the refined weight fractions deviate systematically from their measured values when the method is applied to the mixtures that contain minerals with different degrees of preferred orientation, such as albite-quartz mixtures. The preferred orientation parameters and R-values suggest that the systematic deviation is caused as a result of the preferred orientation effect of feldspar crystallites. It is evident that the preferred orientation corrections are of help for the accurate determination of unit-cell parameters, although they may not improve the result of quantitative analysis significantly. The refined weight fraction of the mineral with higher degree of preferred orientation in mixture is greater than the measured one. This is apparently caused by the effect of geometry of feldspar crystallites in the surface of the mounted sample. The Rietveld refinement method minimizes the problems inherent in the traditional XRD methods, such as the line overlap, primary extinction, and preferred orientation effect, by fitting every data point in a whole pattern explicitly. Furthermore, accurate unit-cell parameters as well as scale factors that can be obtained from the Rietveld refinement are used for the quqantification. The present stdudy demonstrates that the Rietveld method yields far more accurate analytical result than the conventional XRD quantitative analysis method does.