• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.48-52
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• 1982

Methods for the measurement of aquatic bacteria can be divided into two groups. The first group of these methods is based on the 'replicon' concept that live bacterial cells, when diluted and transferred to a suitable medium, produce colonies. These methods distinguish living from dead bacteria, but they massively underestimate bacterial numbers. The second group of enumeration methods uses visual counting technique using specific apparatus such as a microscope. These methods are generally direct and simple, but it is very hard to distinguish between live and dead bacteria and between small particle and bacteria. Recently developed technique in staining methods has provided a reliable method of visual determination of aquatic bacteria. This uses epifluorescence microscopy to measure the total bacterial population. In order to present the fluorescence microscopy as a new methodology for the determination of bacterial numbers in water supplies, data were obtained from chlorine and monochloramine doses added to samples. Total counts by fluorescence microscopy were compared with standard plate count method. The total number of bacteria in water supplies can be determined with fluorescence microscopy. This technique allows better resolution of small bacteria and differentiation of particle from bacteria. Chloramine was found to persist longer in natural waters and prevent bacterial regrowth.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.192-200
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• 2001

The event-based agricultural non-point source(AGNPS) pollution model was applied to estimate the loads of nitrogen and phosphorus in a stream draining small agricultural watersheds. Calibration and verification of the model were performed using observed data collected from rainfall events in the Imgo watersheds during 1997-1998. Parameter calibrations were made for the runoff curve number. The peak flow volumes in the watersheds were well reproduced by the modified model. Average deviation between observed and simulated values was 10%, and this match was confirmed by the coefficient of efficiency value of 0.97. The deviations tended to increase as the peak flows increased. The simulated total N concentrations in the stream water were fairly close to the measured values, and the coefficient of efficiency in the estimation was 0.93. However, there were relatively large variations between calculated and observed values of total P concentration, and the coefficient of efficiency in the estimation was 0.74. Any inaccuracies that arise in estimating runoff flow and nutrient loading can not be explained exactly and further adjustment and refinements may be needed for application of AGNPS in agricultural watersheds. With this restrictions in mind, it can be concluded that AGNPS can provide realistic estimates of nonpoint source nutrient yields.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.481-488
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• 2006

The field scale experiment was performed to examine the performance of the constructed wetland for nonpoint source (NPS) pollution loading reduction. Four sets (0.88 ha each) of wetland and pond system were used. After three growing seasons of the wetland construction, plant coverage increased to about 90% even without plantation from bare soil surfaces at the initial stage. During the start up period of constructed wetlands, lower water levels should be maintained to avoid flooding newly plants, if wetland plants are to start from germinating seeds. The average removal rate of $BOD_5$, TSS, T-N and T-P during the first two years was 5.6%, 46.6%, 45.7%, and 54.8%, respectively. The $BOD_5$ removal rate was low and it might be attributed to the low influent concentration. The early stage of wetland performance demonstrated the effectiveness of water quality improvement and was satisfactory for treating polluted stream waters. From the first-order analysis, T-P was virtually not temperature dependent, and $BOD_5$ and TSS were more temperature dependent than T-N. A pond-wetland system was more effective than a wetland-pond or a wetland alone system in water quality improvement, particularly to reduce T-P. Overall, the wetland system was found to be an adequate alternative for treating a polluted stream water with stable removal efficiency and recommended as a NPS control measures.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.471-480
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• 2006

The field scale experiment was performed to examine the performance of the constructed wetland for nonpoint source (NPS) pollution loading reduction. Four sets (each set of 0.88 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland systems. Water depth was maintained at 0.3-0.5 m and hydraulic retention time was managed to about 2-5 days; emergent plants were allowed to grow in the wetland. The wetland effluent concentrations of $BOD_5$, TSS, and T-N were higher in winter than in the growing season excepting the T-P, and effluent $BOD_5$ concentration was higher than influents in winter. Mass retention of T-N and T-P was stable throughout the year, whereas mass retention of $BOD_5$ and TSS was decreased in winter. $BOD_5$, TSS, T-N, and T-P performance of the experi-mental system was compared with the existing database (North American Treatment Wetland Database), and was within the range of general system performance. From the first-order analysis, T-P was virtually not temperature dependent, and $BOD_5$ and TSS were more temperature dependent than T-N. Overall, the wetland system was found to be an adequate alternative for treating polluted stream water with stable removal efficiency and recommended as a NPS control measures.

• Geotechnical Engineering
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• v.13 no.4
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• pp.37-54
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• 1997

This paper is to investigate the bearing capacity and the failure mechanism of slope subjected to strip surcharges adjassent to embankment slope of sandy soil. Parametric model tests under plain strain condition were performed by changing width of footing, relative density of slope materials, and position of footing from the crest of slopes. For model tests, Jumunjin standard sand was used as the slope material and its relative density was 45% and 70%, respectively. The angle of slope was formed with 1 : 1.5 and 1 2. Rigid model footings, made of aluminuu were used with their widths of 4, 7, 10 and 12cm. For the position of model footing, position ratios, distance of model footing from the crest of slope divided by footing width, were 0, 0.5, 1, 2, 3, 4, 5. Failure mechanism was observed by using ink colored sands and markers inserted in model slopes. Ultimate bearing capacity obtained from tests was analyzed and compared with limit equilibrium method, limit analysis method and empirical equation. Characteristics of load-settlement curves and failure mechanism were also analyzed and compared with the existing theories. Thus, their effects on ultimate bearing capacity of model footing adjacent to slope were assessed.

• Korean Journal of Social Welfare
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• v.35
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• pp.427-451
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• 1998

The purpose of this study is (1) to contrast the welfare state formation in Korea with that in Western European nations, and (2) to examine the historical peculiarities of the Korean welfare state formation process. For the analysis, this study uses' contrast of context' logic of comparative history and contrast the process of (1)modern state formation (2) civil society development (3) interventionist state evolution of Korea with those of Western European nations. The findings of this study are as follows: First, the distingushing role of nation state as welfare provider is very different. It is attributed to the difference in the traditional dominance structure and in the nation-bulding process of each case. Second, class cleavage of the Western Eeuropean nations has been continually mobilized for political action and converted into political resources, while it is impossible to achieve such results in Korea which has continued labor excusive regime. Third, the institutionalization patterns of welfare politics are different. In Western Eeuropean nations, public welfare benefits have been able to produce welfare coalitions and politics of solidarity. By contrast, since welfare have been thoroughly depoliticized and informalized in Korea, voters and political parties have not been able to make issues of welfare problem Due to these historical peculiarities, it seems to be impossible that Korea's underdeveloped public welfare could be changeable in near future.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.81-90
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• 2016

In the civil market, companies launch new products when the acquired innovations are ready, but in defense, customer requests the innovation applied weapon systems. The technology adoption cycle model takes unusual form of market like inverse chasm takes technology inversely. This thesis describes an inverse chasm from the perspective of technology adoption cycle, equipped product model, and technical progress S-curve. As a way to overcome the inverse chasm, considering factors like a self-investment demo model, customer needs, and the temporary chasm expanding phenomenon are derived. And order-effective relationship analysis and chasm marketing strategy are suggested. Especially securing the core technologies and possibility for equipped product by developing self-investment demo model are identified as a good marketing strategy of chasm. This analysis and strategy suggest the policy implications for preemptive advantage of market positioning in the procurement process of defense, discontinuous innovation technology applied on.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.186-193
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• 2010

In order to examine the traits of sluice gate water control, halophyte community formation and their inter-relations in Saemangeum, both water level condition and halophyte community formation were analyzed periodically and spatially on the topographic map with Surfer, Saemageum Spatial Analysis System, and related field reports. The traits of water level condition are that average water level in the growing period of halophytes was similar to annual average water level, annual low level and high level appeared in the growing period, and water level was usually maintained within a range of -1.0m~0.5m above mean sea level, but it has changed more frequently year by year. Routine water level control, natural disaster prevention, construction, and civil appeal took major percentages of the reasons for sluice gate's opening and shutting. Since 2007, not only the overall control frequency of sluice gate but also its control frequency for construction and natural disaster prevention have increased outstandingly. Halophyte community had formed at a rate of 1,209ha/year in the 4,315 ha land in 2008, 6.3 times larger than in 2005, and 2,382 ha above around 1.0m was estimated to be artificially vegetated, 89.1 % of the 2,673ha-size sown area. High water level was found to be a more possible determinant than average water level or low water level in halophyte community formation and it was thought to be secondary factors whether tillage was conducted or/and whether surface sealing formed.

• Clean Technology
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• v.14 no.2
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• pp.123-128
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• 2008

The waste solution, which was discharged from the recovery process of LCD etching solution, consists of 15 wt% nitric acid and 20 wt% acetic acid. In this study, it was conducted to separate acid individually from the mixed acid by vacuum evaporation under -760 mmHg gauge and at $40^{\circ}C$. We have investigated evaporation behavior of acid as a function of temperature. There have been problems that tiny amount of nitric acid were evaporated simultaneously above $33^{\circ}C$. Thus, efforts were conducted to recover acetic acid by vacuum evaporation with adding $H_2O$, waste mixed acid and 20 g/L NaOH for a curb on evaporation of nitric acid. By adding $H_2O$, evaporation of nitric acid was reduced from 7% to 0.78%. However, it was reduced from 7% to 0.25% by adding mixed acid. In view of the results achieved so far, we may expect to separate the etching solution individually by controlling vacuum conditions.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.169-176
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• 2010

A pilot-scale wastewater treatment plant combined with rotating biological contactor and tapered aeration reactors was operated with the wastewater discharged from a food factory for 5 months. The bacterial communities of this plant were investigated by terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analysis of 16S rRNA genes. In spite of high concentration of nitrogen and phosphorus as well as organic carbon, removal efficiency of chemical oxygen demand, total nitrogen, and total phosphorus was 98%, 93%, and 95%, respectively. Bacterial community at the initial operation stage was clearly distinguished from that of the stable operation stage. The most predominant phylum in the sample of stable stage was Bacteroidetes. Major population of operation period was Haliscomenobacter, Sphaerotilus, and candidate division TM7, which were classified as filamentous bacteria. However, sludge bulking caused by these bacteria was not observed. The population that has a close relationship with Haliscomenobacter increased during the stable operation stage, emerging as the most predominant group. These results suggest that the filamentous bacteria participated in nutrient removal when using rotating biological contactor and tapered aeration reactor.