• Proceedings of the Korean Environmental Sciences Society Conference
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• 1998.10a
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• pp.2-4
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• 1998

Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

• Journal of Distribution Science
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• v.14 no.3
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• pp.55-62
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• 2016

Purpose - Average using time of smart-phone for Korean people is 3 hours 39 minutes and most people who are using a computer at home and their workplace can be affected over force to neck and shoulder due to unstable body posture. musculoskeletal disorders which caused by unstable body posture can affect strongly to decrease work efficiency. So this research is designed to measure the effect of using computer & smart-phone on decreased work efficiency due to musculoskeletal disorders and mediating effect between decreased work efficiency and musculoskeletal disorders. Research Design, Data, and Methodology - The author has developed a questionnaire with 6 hypothesis on the basis of previous research result with 5 constructs. The questionnaires were also made by interview and E-mail. 300 copies of questionnaires were distributed and 282 questionnaire were used for the analysis as valid data responses. SPSS ver.21.0 were used and made Cronbach's α and reliability test, correlation, Baron & Kenny 3 step mediated regression analysis. Result - Cronbach's α shows 0.770~0.954 and C.R. is 0.963~0.997 which is higher than 0.7. and AVE was 0.867~0.933. So the data are all acceptable condition. Using for a long time of a computer & smart-phone has a positive effect on musculoskeletal disorders. This means, it can cause musculoskeletal disorders if people use a computer & smart-phone for a long time due to unstable body posture. And musculoskeletal disorders can effect strongly decrease work efficiency. This study also found out that a long time of using computer can cause musculoskeletal disorders rather than using smart-phone a long time. To check mediate effect of musculoskeletal disorders between using a computer & smart-phone and Decreased Work Efficiency, author used 3-step mediated regression analysis of Baron & Kenny (1986). Using a computer for a long time mediate partially and using a smart-phone for a long time mediate completely. This means that using a smart-phone a long time is not the actual reason to decrease work efficiency. But using level of smart-phone is increasing rapidly day by day. So we need to make additional research about this matter seriously. Conclusion - Nowadays, people can not live on without a computer & smart-phone even a moment. But, using a computer for a long time will affect to cause musculoskeletal disorders and it will effect strongly to decrease work efficiency. Before, we thought over that musculoskeletal disorders were diseases of elder people. But, we found out from this study that musculoskeletal disorders can be happen to any people, even children, or workers in heavy industry or engaged in brain work. So we need to be careful when we use a computer for a long time. People also need to be careful to keep correct body posture when using both a computer and smart-phone since a smart-phone became more popular and using time level became longer. Due to increased income and living standard of people, physical growth of young people is so rapid. But the physical environment of society is not suitable for them since it can not follow up the speed of growth. Suitable work table is very important to prevent musculoskeletal disorder which can affect decrease work efficiency. For a person, a society or country, increased productivity is very important since it can directly connected to the job satisfaction. Education and reeducation for the people is also important, but to teach them how to keep good condition of health will be more important since it can increase the quality of work efficiency and quality of life. Computer and Smart-phone is one the best invention of modern society, but it can cause mental and physical disease which can affect decrease work efficiency and productivity. So it is necessary to observe attentively for the situation continually.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.647-653
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• 2007

The ultimate objective of this study is to develop a reliable oxygen-enriched combustion techniques especially for the case of the flue gas recycling in order to reduce the $CO_2$ emissions from practical industrial boilers. To this end a systematic numerical investigation has been performed, as a first step, for the resolution of the combusting flame characteristics of lab-scale LNG combustor. One of the important parameters considered in this study is the level of flue gas recycling calculated in oxygen enriched environment. As a summary of flame characteristics, for the condition of 100% pure $O_2$ as oxidizer without any flue gas recycling, the flame appears as long and thin laminar-like shape with relatively high flame temperature. The feature of high peak of flame temperature is explained by the absence of dilution and heat loss effects due to the presence of $N_2$ inert gas. The same reasoning is also applicable to the laminarized thin flame one, which is attributed to the decrease of the turbulent mixing. These results are physically acceptable and consistent and further generally in good agreement with experimental results appeared in open literature. As the level of $CO_2$ recycling increases in the mixture of $O_2/CO_2$, the peak flame temperature moves near the burner region due to the enhanced turbulent mixing by the increased amount of flow rate of oxidizer stream. However, as might be expected, the flue gas temperature decreases due to presence of $CO_2$ gas together with the inherent feature of large specific heat of this gas. If the recycling ratio more than 80%, gas temperatures drop so significantly that a steady combustion flame can no longer sustain within the furnace. However, combustion in the condition of 30% $O_2/70% $ $CO_2$ can produce similar gas temperature profiles to those of conventional combustion in air oxidizer. An indepth analyses have been made for the change of flame characteristics in the aspect of turbulent intensity and heat balance.

• Microbiology and Biotechnology Letters
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• v.26 no.1
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• pp.7-14
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• 1998

To study the oxygen tolerance mechanism of bifidobacteria, we have studied the growth of cells, the activities of the enzymes which were related with oxygen, such as catalase, superoxide dismutase(SOD), NADH oxidase, and NADH peroxidase, and cellular fatty acid compositions of Bifidobacterium adolescentis and B. longum under anaerobic and aerated (microaerobic and aerobic) conditions. B. longum grew relatively well under the microaerobic conditions, whereas the growth of B. adolescentis was inhibited under the same aerated conditions. B. adolescentis had extremely low level of NADH oxidative enzymes while B. longum had the relatively high level of NADH oxidative enzymes, whose activities were dramatically increased from 3.7 to 11.4 times by microaerobic condition but not in B. adolescentis. The activity of SOD was unexpectedly high in B. adolescentis compared with in B. longum under anaerobic and aerated conditions. The activities of catalase were not detected in all samples tested in this study. We also found that normal $C_{l6:0}$ and $C_{18:1}$ were the major fatty acids in B. adolescentis and B. longum under anaerobic and aerated conditions. 2.2-14.1% $C_{l9:0}$ cyclo fatty acid was detected only in B. longum and the fatty acid was increased by the addition of the aeration. The $C_{l9:0}$ cyclic fatty acid was identified as a cis 9, 10-methylene octadecanoic acid, which was different from lactobacillic acid in the cyclized site. 6.6%-24.6% of dimethyl acetals (DMA) which came from plasmalogen were observed in the B. adolescentis and B. longum grown under anaerobic condition, and the components were notably decreased in the cells grown under the aerated conditions. It is believed that NADH oxidative enzymes play an important role to detoxify oxygen metabolites of Bifidobacteriurn spp. under anaerobic and microaerobic conditions. Independently from oxidative enzymes, it seems that oxygen stress may induce the change of the level of cellular fatty acids showing an increase of $C_{l9:0}$ cyclo in B. longum and a decrease of $C_{l8:1}$ of plasmalogen in B. longum and B. adolescentis to adapt in environment.

• Korean Journal of Poultry Science
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• v.39 no.3
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• pp.183-193
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• 2012

This study was conducted to investigate the effect of feeding the electrolytic materials on blood and carcass traits of broiler during transportation exposed under intense heat condition in summer. The broilers were selected on the day when the outside temperature was about $32^{\circ}C$ to provide heat stressed environment. Broilers reared for 33 d were selected and fed with the electrolytic materials ($NaHCO_3$, NaCl, KCl) for 2 days. Treatments were as follows; feeding the underground water for control, $NaHCO_3$ (1.0%) + NaCl (0.5%) for treament 1, KCl (0.5%) + NaCl (0.5%) for treatment 2, KCl (1.0%) + NaCl (0.5%) treatment 3, KCl (0.5%) + $NaHCO_3$ (1.0%) + NaCl (0.5%) for treatment 4 and KCl (1.0%) + $NaHCO_3$ (1.0%) + NaCl (0.5%) for treament 5. pH of chicken meat increased for treatments group of electrolytic material, especially, that of treatment 3 was highest when compared to the other treatments. The frequency rate (%) of $1^+$ quality grade were 33.3, 60.0 and 83.3% at control, treatment 3, 4 and treatment 5, respectively. Occurrence rates of PSE were 50% for control and 13.3% for treatment 5. Corticosterone increased at the post-harvest period compared to the pre-harvest period of broiler and have small disparity between pre-and post-harvest only except treatment 3 when compared to control. $pCO_2$ partial pressure of blood at the pre-harvest period was low in all treatments by heat stress, the disparity value of control was high for control, and those of treatment 4 and 5 were low compared to other treatments.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.390-399
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• 2014

The objective of this study was to establish a processing technology for preserved leaves based on the results from the examination of the optimal period and condition for dye-absorbing treatment for Eucalyptus cinerea F. Mull. ex Benth. (silver dollar eucalyptus) being used frequently as plant material for flower design. Cut foliages of E. cinerea with uniformly matured leaves were cut into 20 cm lengths and their lower stem parts were placed in dye solution in growth chambers with different temperatures (10, 20, 30, and $40^{\circ}C$), vapor pressure deficits (VPD; 0.23, 0.70, 1.17, and 1.61 kPa), and photoperiods (0, 6, 12, 24 hours) for 3, 6, 9, and 12 days, and then dried in a room of $20^{\circ}C$ for three days. Lower temperature during preserving dye treatment reduced the changes in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. Especially, high temperature increased red degree (a) and decreased yellow degree (b) due to browning. Lower VPD reduced the change in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. Shorter photoperiod reduced the change in leaf color compared with fresh leaves and decreased ${\Delta}E$ value. The ${\Delta}E$ value increased with increasing absorbing duration under three environmental conditions. The flexibility of stem and leaves after dipped into preserving dye solution and dried for 3 days increased with decreasing temperature, VPD and dipping duration. Therefore, the optimal environment condition for dye treatment was 0.23-0.70 kPa VPD at $10-20^{\circ}C$ in the darkness, and the optimal and economical duration was 3 days. These conditions reduced the speed of water loss by decreasing transpiration, so yellowing or browning by rapid water loss deteriorated the quality of preserved leaves out of these ranges.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.77-85
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• 2008

Grazing rates (GR) and pseudofaeces production (PFP) of native snail, Chinese mystery snail (Cipangopaludina chinensis malleata Reeve) on natural colonial morphs of Microcystis aeruginosa was measured. C. chinensis was collected from the upstream of the Geum River (Boryeong, Korea), where they co-habituated with Unio douglasiae and Lanceolaria acrorhyncha. The experiments were performed to evaluate the GR and PFP at different conditions such as; incubation time (1, 3, 5, 7, 9 and 11 hr), body size (3 to 6.1 cm, n=28), snail density (0.5, 1, 1.5 and 2.0 ind. $L^{-1}$) and prey concentration (168.3, 336.7, 505.0 and $673.0{\mu}g\;Chl-{\alpha}L^{-1}$). All experiments were triplicated, and conducted in transparent acrylic vessel (3L in volume). Regarding feeding time, a highest GR (0.538L $gAFDW^{-1}h^{-1}$) and PFP $(7.18mgAFDW^{-1})$ appeared at 1hr and 7hr after snail stocking, respectively. Interestingly, the snail, smaller than 4.5cm in body size, showed a wide range of GR ($-4.173{\sim}1.087L\;gAFDW^{-1}h^{-1}$) for the initial period (1 and 4hrs of stocking), compared to those greater than 4.5cm, which showed a stable FR, higher than 0.5L $gAFDW^{-1}h^{-1}$. Upon density effect, the density of 1.5 ind. $L^{-1}$ induced the most effective inhibition on Microcystis biomass with highest PFP. On the prey concentration, highest GR (0.897L $gAFDW^{-1}h^{-1}$) and PFP (3.67 mg $gAFDW^{-1}h^{-1}$) were induced at the level of $168.3{\mu}g\;Chl-{\alpha}L^{-1}$ and $673{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. GR and PFP of this freshwater snail on the cyanobacterial bloom (M. aeruginosa) varied with the feeding conditions, and they were comparatively high for a short period of time less than 7hrs regardless of the stocking condition. Our results suggest that this freshwater snail has a potential to control cyanobacterial bloom when provided with suitable condition.

• Conservation Science in Museum
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• v.19
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• pp.1-18
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• 2018

The Stele for National Preceptor Hongbeop from the Jeongtosa Temple site in Chungju is one of the most important stone cultural heritage items for exemplifying the style of the Goryeo era. Despite its obvious value, this relic has been stored in a weathered condition at the National Museum of Korea. It had suffered various dismantling and displacements during the Japanese colonial period and had long been exposed in the open air. The stele was selected as a subject for the Stone Monuments Restoration Project launched by the National Museum of Korea in 2015. In preparation for its outdoor exhibition as part of the restoration project, this study investigated the characteristics of its materials, produced a map of its deterioration from weathering, and carried out ultrasonic analysis of the materials to provide findings useful for conservation treatment. The materials analysis revealed that the turtle-shaped pedestal of the stele was made from two-mica granite consisting of medium-grained quartz, plagioclase, alkali feldspar, biotite, and muscovite. Its body stone is crystalline marble, the rock-forming mineral in which is medium-grained calcite in a rose-pink color with dark grey spots. The dragon top of the stele is made of crystalline marble, the major component of which is medium-grained calcite of a light-grey color. The deterioration consists of 21.5% abrasion on the stone body, with its south face most damaged, and 18.6% granular disintegration, with the north face most damaged. The ultrasonic material characterization conducted for mapping the general condition of weathering shows low values on the parts-assembly area of the turtle-shaped pedestal and on the upper portion of the stone body. It is considered that there is dislocation due to partial blistering and fracturing as well as to the differences in surface treatment. Prior to the outdoor exhibition of the stele, the surface was cleaned of contaminants and was consolidated based on the scientific investigation in order to prevent weathering from the external environment.

• Land and Housing Review
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• v.4 no.1
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• pp.77-87
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• 2013

About 1,800 villages have released from Greenbelt since Greenbelt-reform-policy for readjustment of the area was promoted after 1997. Even though the government intended to attract planned development & improvement of these lifted villages through District Unit Plan and designating the lifted area as low-rise and low-density zoning considering the characteristics of the Greenbelt region, there are still many problems to be solved: a lack of funds, insufficient capability for self-improvement and unexecuted SOCs in long-term etc. It seems that these problems are caused by focusing on the lifting areas itself instead of researching deeply the condition and characteristics of the villages and searching proper direction/plans of improvement before lifting Greenbelt In addition, the existing plan of village improvement and management was not considering physical and spacial characteristics of the areas, social and economic situation of residents and relationship between the villages and surrounding cities, though these conditions are different among each villages, and the related regulations are applied uniformly across all the villages and those have been causing many civil appeals and environmental problems. In these respects, this study aims to consider the problems of the lifted villages using the existing researches on them and to make typology by characteristics-data of the villages and to establish improvement strategies of each types. In this study, the villages were classified into 5 types as a result of cluster analysis on 424 villages among all 1,800 through variables of locational potentiality : location, accessibility, size and form of village, condition of regulations etc. According to function of the villages, they were divided into 4 types: urban-type, rural-type, industrial-type and neighborhood-centered-type. This study also drew 4 improvement-strategy-types by combination of locational potentiality and village-function : type of improving life-environment, type of improving production-infra, type of inducing-planned-improvement and type of constructing center-of living-circle. Finally, this study suggested the directions of the each 4 types to desirable improvement and management which could be used to make and complement plans for village improvement.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.1
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• pp.39-48
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• 2010

Recreation forests are in the spotlight as the place for personality development, mind and body comfort, companionship, and environment education in forests and valleys. Visitors to recreation forests have been on the increase along with booming in recreation forest building since 1988. Recreation forests are being categorized according to some features such as regional and environmental condition. Recreation forests, however, have not met the expectations of some visitors who want to take a rest with calmness due to the influence of the 5-day-work-week system, increasing interest in rest, leisure, and well-being, and users converge during weekends, summer, and the tourist season. In order to improve visitors' satisfaction efficiently, this study surveyed the level of satisfaction in each cluster based on the precedent study which had classified 85 national or public recreation forests in Korea into clusters. Questionnaires were distributed properly to each cluster and, of the 1,132 questionnaires collected, 1,015 were valid and used for analysis. Reliability of questionnaires and statistical validity of the model were verified. As a result, there are meaningful differences in the ranking of independent variables which affect the level of satisfaction according to clusters. Variables in rest and fatigue recovery have the strongest influence on the level of satisfaction in the clusters of potential factor, internal activation factor, and mixed potential capacity factor. In the use performance and visiting condition factor cluster, appropriateness of visit cost is most influential and, in the education cluster, connectivity with tourist attractions around it is most affective. These results can provide priority in services and maintenance of recreation forests for improving the level of satisfaction and differentiate the distribution of resources according to clusters.