• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.46-52
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• 2007

As flue gas desulfurization (FGD) wastewater contains high concentrations of nitrate and is very low in organic carbon, the feasibility of nitrate removal by autotrophic denitrification using Thiobacillus denitrificans was studied. This autotrophic bacteria oxidizes elemental sulfur to sulfate while reducing nitrate to elemental nitrogen gas, thereby eliminating the need for addition of organic compounds such as methanol. Owing to the unusually high concentrations of dissolved salts $(Ca^{2+},\;Mg^{2+},\;Na^+,\;K^+,\;B^+,\;SO_4^{2-},\;Cl^-,\;F^-,)$ in the FGD wastewater, extensive laboratory-scale and pilot-scale tests were carried out in sulfur-limestone reactors (1) to determine the effect of salinity on autotrophic denitrification, (2) to evaluate the use of limestone for pH control and as source of inorganic carbon for microbial growth, and, (3) to find the optimum environmental and operational conditions for autotrophic denitrification of FGD wastewater. The experimental results demonstrated that (1) autotrophic denitrification is not inhibited up to 1.8 mol total dissolved salt content; (2) inorganic carbon and inorganic phosphorus must be present in sufficiently high concentrations; (3) limestone can supply effective buffering capacity and inorganic carbon; (4) the high calcium concentration may interfere with pH control, phosphorus solubility and limestone dissolution, hence requiring pretreatment of the FGD wastewater; and, 5) under optimum conditions, complete autotrophic denitrification of FGD wastewater was obtained in a sulfur-limestone packed bed reactor with a sulfur:limestone volume ratio of 2:1 for volumetric loading rates up to 400g $NO_{3^-}N/m^3.d$. The interesting interactions between autotrophic denitrification, pH, alkalinity, and the unusually high calcium and boron content of the FGD wastewater are highlighted. The engineering significance of the results is discussed.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.99-105
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• 1994

In this study we compared traditional cheesemaking process with the process utilizing ultrafiltration(UF) system. The whole milk retentates were prepared by ultrafiltration to volume concentration ratio(VCR) of 2.00:1, 2.25:1 and 2.50:1. Along with the untreated whole milk, there were studies in terms of the change of pH, titratable acidity and Soxhlet-Henkel($\circ $SH) value by mesophilic lactic starter and curd formation by rennet during Gouda cheese manufacture. Due to the increase of buffering effect titratable acidity and $\circ $SH value increased with the higher concentration ratio. When inoculated with the same volume of mesophilic lactic starter, less pH change occurred in UF retentates than in control milk. When added 0.0025% rennet, UF retentates coagulated 16~ 17 minutes ealier then the control milk. Gouda cheese yield from raw milk and UF retentates was 12.5~13.1% equally, but yield efficiency of UF retentate cheese was slightly higher than that of the raw milk cheese. Quantity of whey from retentate cheese was inversely related to VCR. But whey from retentate cheese contained higher percentage of amjor components than that from control milk cheese. In early ripening, the concentrations of lactose and soluble nitrogen compound were higher in retentate cheeses. Lactose content of control milk cheese was 3.49% and that of 2.00:1. 2.25:1, 2.50:1 VCR retentate was 3.77%, 4.89%, 7.03%, respectively. Thus, the more concentrated cheese contained a higher amount of lactose and all the lactose was hyerolyzed durion 35-day ripenion period. Soluble nitrogen compound of control milk cheese was 1.22% and that of UF cheeses was 1.82~2.06%. After 20-day ripening, soluble nitrogen compound increased starply in UF cheese.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.1926-1940
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• 1998

This paper is the part II of research results on the performance evaluation of fully interconnected ATM switch, and includes the performance evaluation results for bursty traffic and nonuniform distribution. The switch model is a fyully interconnected switch type proposed by ETRI and is the proper architecutre for a small-sized switch element. The proposed switch consists of two steps of buffering scheme in the switch fabric in order to effectively absorb the effect of bursty nature of ATM traffic. The switch uses bit addressing method for addressing shcmeme and thus it is easy to implement multicasting function without adding additional functional block. In order to incorporate the bursty nature of traffic in ATM networks, we use IBP(Interrupted Bernoulli Process) model as an input traffic model as well as random traffic model which has been used as a traditional traffic model. In order to design the various scenarios for simulation, we considered both uniform and nonuniform output distribution, and also implemented multicast function. In this paper, we presented the simulation results in diverse environments and evaluated the performance of the switch.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.465-468
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• 2008

Recently, VOD market is getting increased and most of public, educational organization, enterprises are providing service as content managing system of WMV standard subordinated to Window OS of Microsoft company. VOD CMS of WMV standard have problem that frequent cut-off, small-size of screen, and image quality which is also chronic problem. In order to solve this problem, technology solving the problem has developed through minimization of buffering time, screen size, high quality sound, and high quality image by image codec and streaming engine which is H. 264. But there are still a problem that systematic management of contents or distribution is difficult. This study expected that there would be a effect preoccupying significant stand of world wide H.264 high quality image mobile VOD managing market by securing domestic on-line VOD contents integrated managing technology by designing system for image VOD contents management having a limit in wmv market and combining H.264 which is new technology.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.1-11
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• 2014

Sympathetic detonation (SD) of high explosives occurs when a detonating donor initiates neighboring acceptors. The present study focuses on the hydrodynamic simulation of one-on-one sympathetic detonation of 155 mm charge filled with PBXN-109. Both unbuffered and buffered SD configurations are performed while changing the distance between each charge, in order to investigate the detonation sensitivity to a donor initiation. The cause of a SD is by a shock impact for the unbuffered case at a close range, while at a distant range, blast fragment penetration is the primary cause. The buffers can reduce the incident sensitivity to a SD by reducing the strengths of shock wave and impinging fragments.

• Journal of the Korea Safety Management & Science
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• v.24 no.4
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• pp.49-59
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• 2022

Mt. Umyeon is a low-altitude mountain near a residential area, and the actual forest area is not large due to the fact that development for use as a living green space is being completed and in progress across the mountain, so the buffering action for landslides was weak. The unit was located at the top of Mt. Umyeon, and there were reports of contents related to the military unit in some accident areas. Some experts suggested that the landslide that started on the cut side of the unit could be one of the causes of the landslide at Mt. Umyeon. It is presumed that there was a sudden collapse of trees that had fallen due to erosion inside the valley. In the case of the Umyeon landslide, localized torrential rain is the biggest cause, but the fact that it suffered a lot of damage is the result of no preemptive measures. In particular, it can be said that the damage was caused by the concentration of residential and commercial facilities due to the unplanned urban expansion without prior review of the feng shui geography of settlement areas. The important lesson we have learned is that we should recognize nature as living things and live in harmony and coexistence between humans and nature through understanding and cooperation. Adapting to changes in the environment can survive, but if it doesn't, it will be slaughtered. As such, geography influences changes in feng shui. Changes in feng shui have a profound effect on not only humans but also the natural ecosystem.

• Journal of Ecology and Environment
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• v.47 no.1
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• pp.1-13
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• 2023

Background: The positive effects of Arctic plants on the soil environment and plant-species co-occurrence patterns are known to be particularly important in physically harsh environments. Although three dominant plants (Cassiope tetragona, Dryas octopetala, and Silene acaulis) are abundant in the Arctic ecosystem at Ny-Ålesund, Svalbard, few studies have examined their occurrence patterns with other species and their buffering effect on soil-temperature and soil-moisture fluctuation. To quantify the plant-species co-occurrence patterns and their positive effects on soil environments, I surveyed the vegetation cover, analyzed the soil-chemical properties (total carbon, total nitrogen, pH, and soil organic matter) from 101 open plots, and measured the daily soil-temperature and soil-moisture content under three dominant plant patches and bare soil. Results: The Cassiope tetragona and Dryas octopetala communities increased the soil-temperature stability; however, the three dominant plant communities did not significantly affect the soil-moisture stability. Non-metric multidimensional scaling separated the sampling sites into three groups based on the different vegetation compositions. The three dominant plants occurred randomly with other species; however, the vegetation composition of two positive co-occurring species pairs (Oxyria digyna-Cerastium acrticum and Luzula confusa-Salix polaris) was examined. The plant species richness did not significantly differ in the three plant communities. Conclusions: The three plant communities showed distinctive vegetation compositions; however, the three dominant plants were randomly and widely distributed throughout the study sites. Although the facilitative effects of the three Arctic plants on increases in the soil-moisture fluctuation and richness were not quantified, this research enables a deeper understanding of plant co-occurrence patterns in Arctic ecosystems and thereby contributes to predicting the shift in vegetation composition and coexistence in response to climate warming. This research highlights the need to better understand plant-plant interactions within tundra communities.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.465-473
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• 2016

This study was carried out to evaluate restoration process of a few wetlands in the National Institute of Ecology (NIE). Wetlands were composed of the former rice paddies that passive restoration was led through only natural process and by creating waterway, and an ecological pond, a reservoir that restorative treatment was practiced. As the result of analysis on landscape change in the current wetland space, existing wetland in NIE was usually from the former rice field and some parts were from the residential area or forest. Change of species composition was progressed from crops or ruderals resistant to human interferences to plant species, which has removed artificially for cultivation and grow usually in the typical wetland. Both species diversity and occurrence of exotic plants were the highest when restoration project is in progress and stages after and before restoration were followed. In an ecological pond that restorative treatment was done, vegetation introduced as riparian buffer was established successfully and thereby it was expected that it could contribute to buffer environmental stress comming from the outside. Synthesized the above mentioned results, change of wetland vegetation established in NIE resembled the typical trend of early successional stage occurring in the abandoned rice paddy and consequently, it was estimated that successful restoration is under progress. Restoration under progress in an ecological pond where artificial aid in the least level was added, could be evaluated in successful as well. In particular, successful establishment of buffering vegetation, which can play diverse ecological functions, could be evaluated as significant restoration effect. But adaptive management to improve ecological quality for the section that buffering vegetation is insufficient, is required.

• Korean Journal of Food Science and Technology
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• v.30 no.2
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• pp.425-433
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• 1998

The characteristics of the reaction of calcium carbonate $(CaCO_3)$ immobilized with alginate as buffer system for the high concentration cultivation of bifidobacteria in fermenter are described by the mathematical model, and tested for the reusing possibility of the used $CaCO_3$ beads. When$CaCO_3$ beads with the various diameters were reacted in 0.1 M of the mixed organic acids (0.6 M of acetic acid and 0.4 M lactic acid) and in fermenter inoculated Bifidobacterium longum ATCC 15707, the change of bead diameters can be calculated with the amount of the decreased $CaCO_3$ from the surface of bead using the mathematical model. These values was similar to the directly measured bead diameter by a micrometer. Therefore, it was considered that the mathematical model could be used for explaining the reaction charateristics of the $CaCO_3$ bead reacted with the organic acids. When Bifidobacterium longum was incubated at $37^{\circ}C$ for 20 hours in fermenter with $CaCO_3$ beads, the buffering effect of $CaCO_3$, the reduce rate of the bead diameter, and the growth rate of Bifidobacterium longum were higher at the smaller beads than beads with the larger diameters. Also, when Bifidobacterium longum was incubated in fermenter with the mixed beads which were added new beads to the recovered beads in order to equalize with the total surface area of initial beads, the buffering effect of $CaCO_3$ bead and the growth rate of Bifidobacterium longum were very corresponded with the results of the fermentation using the only initial beads. Therfore, it is expected that the used beads can be reused by adding the initial beads.

• Journal of Korean Academy of Nursing
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• v.20 no.3
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• pp.414-429
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• 1990

Numerous research reports have substantiated the role of stressful life events in relation to the onset of health changes. The relationship tends to hold across different age groups. Theoretically, adolescence has been considered a developmental crisis period of great stress, impoverished coping skills and high vulnerability to biological, social and psychological demands. The research problem addressed by this study was to examine the relationships between stressful life events and health symptom patterns, and the effect of two variables, coping and social, support, theoretically considered to mediate the relationship between stress and health symptoms in adolescents. The following five hypotheses were tested in this research : 1. Health symptoms are positively related to stressful life events in adolescents, 2. Health symptoms are negatively related to coping in adolescents, 3. Health symptoms are negatively related to social support in adolescents, 4. When coping is controlled, the relationship between health symptoms and stressful life events will decrease, and 5. When social support is controlled, the relationship between health symptoms and stressful life events will increase. The study subjects consisted of 1090 high school students of the metropolitan city of Seoul. The following sampling procedure was used : 1. Of the 169 high schools in nine school administrative districts in the city, a proportional sample of ten schools was selected. 2. One class from each of the freshman and sophomore was randomly selected and all the students who were in the sampled class were used as the study sample. The study was limited to freshman and sophomore adolescents, aged 15 to 18(mean＝16.6). Of the 1090 subjects 688(63%) were boys and 402(37%) were girls. An Adolescent Inventory of Stressful Life Events, a Health Symptom Questionnaire and an Adolescent Coping Inventory were adapted for this study. The Norbeck Social Support questionnaire was utilized to collect the data on perceived social support. Five high school teachers in the areas of school health and counselling reviewed the items of each questionnaire for content validity. A pilot study was undertaken to ascertain reliability. Fifty three high school students responded to the questionnaires and gave their opinions on the items. For stressful life events, health symptoms, coping, and social support, the Cronbach's alpha's on the study were .70, .94, .77, and .76, respectively. Research assistants attended all the sampled classes with the school proctor to explain the purpose and procedures of the study to the students. The questionnaires along with a ballpoint pen were distributed to the students who were asked to complete each item. The research assistants left the ballpoint pen with the students as a gift for their cooperation. An average of 50 minutes was required to complete the questionnaires. Using an SPSS, the first, three hypotheses were tested using Gamma, a measure of association for ordinal variables. Partial gamma was used to test the fourth and fifth hypotheses. Patterns of elaboration described by Babbie were selected to interpret the relationship of the three variable analyses. The significance of gamma was determined by Chisquare at a .05 level of significance. There was a positive relationship between health symptoms and stressful life events(Gamma＝.35, p＝.000). Thus the first hypothesis was supported. Unexpectedly, coping was positively related with health symptoms(Gamma＝.13, p＝.000). That is, the higher the coping levels, the greater number of health problems. The third hypothesis, the higher the level of social support, the fewer the health symptoms, was not accepted in this adolescent study group. When coping was controlled, under the condition of low coping the association between health symptoms and stressful life events increased significantly to a partial gamma of .39, and under the condition of high coping it was .30. According to the elaboration model, when one partial relationship is the same or greater than the original and the other is smaller, the control variable should be considered to be specifying the conditions. When social support was controlled the relationship between stressful life events and health symptoms increased under the condition of low social support, but with high social support, the relationship decreased. Both partial gamma were statistically significant at .05 level(.43 and .26 relatively). It can be interpreted that stressful life events are strongly and positively related to health symptoms under the condition of low social support, however this relationship can not be expected with high social support. Thus, the last two hypotheses were conditionally sustained. In this study, the relationships between stressful life events and health symptoms, and the specified me diating roles of coping and social support were found to have statistical interaction. This finding supports the theoretical position of this study. It suggests that stressful life events would create high susceptability to biological social and psychological health symptoms and coping and social support buffering the relationship between stressful life events and health symptom. The findings of this study have implications for nursing practice. When adolescents are confronted with non-developmental life events that are perceived as stressful, nurses should recognize the evidence of the stress-buffering effect of coping and social support on health symptoms and utilize the diverse sources of social support that are readily available to adolescents.