• Journal of Korea Water Resources Association
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• v.45 no.5
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• pp.431-444
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• 2012

This study investigated the differences between annual maximum series and annual maximum independent rainfall event series with relatively short and long rainfall durations. Annual maximum independent rainfall events were selected by applying various IETDs and thresholds to the hourly rainfall data in Seoul for the duration from 1961 to 2010. Annual maximum independent rainfall event series decided were then compared with the conventional annual maximum series. Summarizing the results is as follows. First, the effect of IETD and threshold was not beyond the expected level. For example, as the IETD increases, the frequencies of independent rainfall events decreased similarly in their rate for both with short and long durations. However, as the threshold increases, the frequency of those with rather long durations decreased much higher. Second, The mean rainfall intensity of the independent rainfall events was found to remain constant regardless of their duration. This indicates that the annual maximum rainfall intensity could be found in a rainfall event with longer durations. Lastly, the difference between the annual maximum rainfall series and the annual maximum independent rainfall event series with rather short rainfall durations was found significantly large, which decreases with longer durations. This result indicates that the conventional data analysis method, especially for small basins with short concentration time, could lead an unrealistic design rainfall with little possibility of occurrence.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.535-542
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• 2016

As one of the most cost-effective methods for surface emission measurements, flux chamber method has been used worldwide. It can be classified into two types: SFC (with slope method) and DFC (with steady-state method). SFC (static flux chamber) type needs only simple equipment and is easy to handle. However, the value of flux might vary with SFC method, because it assumes that the change of concentration in chamber is linear with time. Although more specific equipments are required for DFC (dynamic flux chamber) method, it can lead to a constant result without any ambiguity. We made a self-designed DFC using a small and compact kit, which recorded good sample homogeneity (RSD < 5%) and recovery ( > 90%). Relative expanded measurement uncertainty of this improved DFC method was 7.37%, which mainly came from uncontrolled sweep air. The study shows that the improved DFC method can be used to collect highly reliable emission data from large landfill area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.237-245
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• 1999

Rates of photosynthesis and respiration of Laminaria japonica sporophytes cultivated on the southeastern coast of Korea were monthly measured in situ and under constant temperature and nitrogen concentration in laboratory from February to July 1996 in order to understand the seasonal photosynthetic performance of this alga. P-I (the relationship between photosynthsis and irradiance) parameters measured in situ varied seasonally. Photosynthetic capacity ($P_{max}$) reached its maximum in March (6.64 mg $O_2{\cdot}gdw^{-1}{\cdot}h^{-1}$) and gradually decreased thereafter. Photosynthetic efficiency (${\alpha}$), which ranged from 0.026 to 0.106, generally showed a similar pattern with the $P_{max}$, curve. Correlation between respiration and $P_{max}$, was not significant (Spearman's rank correlation, p>0.05); respiration rate, which varied between 0.25 and 0.83 mg $O_2{\cdot}gdw^{-1}{\cdot}h^{-1}$, showed no gradual decline from March. $P_{max}$ in situ significantly correlated with the relative growth rate of frond weight (Spearman's rank correlation, p<0.01) and this result means that the amount of accumulated materials in body increased with the increment of $P_{max}$. Compared $P_{max}$, in situ with that in the laboratory. The lower $P_{max}$ in February was probably caused by the effect of lower seawater temperature at this time. The decrease in $P_{max}$ after March, however, was primarily attributable to the thickness of blade as the plants got old. Comparison of P-I parameters measured for different size groups in April, explained the negative relationship between $P_{max}$ and frond thickness.

• Journal of Nutrition and Health
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• v.28 no.4
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• pp.345-354
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• 1995

Blenderized diets are not recommended because of difficulties in providing a constant content of nutrients, phoblems with viscosity and osmolarity, time needed for preparation, and increased risk of contamination. To determine the possibility of substituting commercial formulas for blenderized diets, 27 unconscious patients were randomized into two different groups : blenderized diet group(n=11) and commercial formula group(n=16). Blenderized diets were composed of food sources such as rice, milk, egg, juices and others, and its energy percentage of protein, fat, and carbohydrate was 15%, 30%, and 55%, respetively. Commercial enteral formulas provided 1 kcal/ml and the energy percentage of protein, fat and carbohydrate was 25%, 20% and 55% in greenbia(G) and 20%, 20%, and 60% in Greenbia-DM(GD), repectively. In commercial formula group, five patients with diarrhea, constipation, and high blood glucose level received GD, and the other eleven patients received G. All patients received their lipuid diet for 4 weeks through 16 French rubber nasogastric tube by bolus feeding 6 times daily. The patients in commercial formula group had a similar mean daily calorie intake to the patient in blenderized diet group, 32-34kcal/kg/d and 30-35kcal/kg/d, respectively. Patients given commercial formula gained an averge of 1.7kg in weight but those given blenderized diet lost an average of 2.6kg. There was a trend toward an increase in percent ideal body weight in commercial formula group(94$\pm$5 vs 99$\pm$6%). However, blenderized diet group showed a trend toward a decrease in percent ideal body weight(106$\pm$5 vs $101\pm$6%). The initial levels of total lymphocyte counts, serum albumin and tranferrin were below the normal rante, The mean daily protein intake was significanlty higher for commercial formula group(2.0-2.1g/kg/d) than for blenderized diet group(1.1-1.3g/kg/d). Patient fed cormmercial formula for 4 weeks showed a trend toward an increase in serum albumin(8.1%) and a significant increase in serum transferrin(32.1%) without increasing the levels of blood glucose. GOT, GPT, blood urea nitrogen and serum creatinine. In the blenderized diet group, however, no significant improvement were obseved in the concentration of serum albumin and transferin, compared to initial value. There was a trend toward a decrese in the level of hemoglobin and hematocrit in blenderized deit group but no significnat change in commercial formulas goups. All patients tolerated both diets well and no significant complications were encountered. The results indicate that the commercial enteral formulas tested in this study can be an effective substitution for blenderized diet in unconscious tube-fed patients.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.278-284
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• 2016

Software reliability in the software development process is an important issue. In infinite failure NHPP software reliability models, the fault occurrence rates may have constant, monotonic increasing or monotonic decreasing pattern. In this paper, infinite failures NHPP models that the situation was reflected for the fault occurs in the repair time, were presented about comparing property. Commonly, the software model of the infinite failures using the linear hazard rate distribution software reliability based on intercept parameter was used in business economics and actuarial modeling, was presented for comparison problem. The result is that a relatively large intercept parameter was appeared effectively form. The parameters estimation using maximum likelihood estimation was conducted and model selection was performed using the mean square error and the coefficient of determination. The linear hazard rate distribution model is also efficient in terms of reliability because it (the coefficient of determination is 90% or more) in the field of the conventional model can be used as an alternative model could be confirmed. From this paper, the software developers have to consider intercept parameter of life distribution by prior knowledge of the software to identify failure modes which can be able to help.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.1-8
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• 2006

The objective of this study is to assess impacts of sorption heterogeneity on the transport of leachate leaked from unlined landfill sites and is accomplished by examining the results from a series of Monte-Carlo simulations. For random distribution coefficient ($K_{d}$) fields with four different levels of heterogeneity ranging from homogeneous to highly heterogeneous, the transport of leachate was investigated by linking a saturated flow model with a contaminant transport model. Impacts of a chemical heterogeneity were evaluated using point statistics values such as mean, standard deviation, and coefficient of variation of the concentration obtained at monitoring wells from 100 Monte-Carlo trials. Inspection of point statistics shows that the distribution of distribution coefficient in the landfill site proves to be an important parameter in controlling leachate concentrations. In comparison to homogeneous sorption, heterogeneous $K_{d^-}$ fields produce the variability in the leachate concentration for different realizations. The variability increases significantly as the variance in the $K_{d^-}$ field and the travel time between source and monitoring well increase. These outcomes indicate that use of a constant homogeneous $K_{d}$ value for predicting the transport of leachate can result in significant error, especially when variability in $K_{d}$ is high.

• Korean Journal of Medicinal Crop Science
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• v.21 no.5
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• pp.329-333
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• 2013

This study was carried out to compare the characteristics of seed germination and the first stage of growth in Cynanchum wilfordii (Maxim.) by different light conditions such ass fluorescent light, dark and light emitting diode (LED). There was not much difference from the germination rate of C. wilfordii (Maxim.) in different light conditions for 10 days. The highest of germination rate occurred over 91.11 percentage by LED red condition at $26^{\circ}C$. Also mean germination velocity and promptness index were represented the highest results of 2.3 ea/day and 52.67 under red light, respectively. But mean germination time under both LED red and blue light was represented low data that it takes over three days for germinating of seed. Even though handling both LED red and blue lights, the germination uniformity was not constant. These results may help our understanding of variations in germination characteristics for C. wilfordii (Maxim.) seeds treated under different light conditions.

• Solar Energy
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• v.15 no.2
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• pp.77-90
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• 1995

An effective heat transfer during freezing process was proposed in the vertical cylinder to improve the effectiveness of the heat storage. Vertical cylinder was filled with pure water in order to investigate ice-shape, temperature distribution of the liquid, temperature distribution of the cylinder tube wall, total heat storage per unit mass in the test section under the two experimental conditions; inlet temperature of working fluid is constant($-10^{\circ}C$) and inlet direction of working fluid is either upward flow or downward. Both the mean temperature of the liquid and temperature difference of cylinder tube wall in the upward were lower than those in the downward. In case that the initial temperature of water was $7^{\circ}C$ and $4^{\circ}C$, the shape of ice layer in the upward was more uniform than that in the downward. In case of $1^{\circ}C$, the shape of ice layer is formed by inlet direction of working fluid. Finally, time-varying total heat energy stored in the water in the upward was higher than that in the downward.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.4
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• pp.326-332
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• 2021

Swabs are useful and common sampling tools in various research fields, such as medicine, ecology, biotechnology, forensic medicine, and pollutant monitoring systems. Collection reagents are one of the essential components in sampling. It is important to develop a sample collection kit and designate an appropriate storage temperature because samples need to be stored for a long time. The purpose of this study was to identify the effects of three collection reagents and three storage temperatures on the recovery of living bacteria without media. We selected Escherichia coli and Staphylococcus aureus as representative environmental bacteria. Distilled water (DW), phosphate buffered saline (PBS), and Tris-EDTA (TE) buffer were used as collection reagents and stored at 22℃, 4℃, and -70℃ after sampling. The results of using each collection reagent and storage temperature on the bacteria were compared using relative light units (RLU) and the number of colony forming units (CFU). When using -70℃ storage temperature and the TE buffer, the number of living bacteria and the RLU values remained constant. It is therefore recommended that the sample be stored at -70℃ immediately after collection and a TE buffer solution be used as the collection reagent.

• Journal of The Korean Association For Science Education
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• v.41 no.6
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• pp.501-517
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• 2021

In the present age, when the development of science and technology is leading the changes, this study supports the view that students should possess the literacy to participate democratically and critically in socio-scientific issues, and should be positioned as agentic and participatory citizens. Accordingly, we implemented a club activity that emphasize climate social action for elementary students, and explored how students were positioned in relation to climate change. In this study, position is defined as a complex cluster of rights and duties that students have in relation to climate change. The club activity was implemented throughout 46 sessions from March to July, 2019 for 11 sixth graders of 'H elementary School' in Seoul, and transcripts of video and interviews were analyzed by means of a constant comparison method. In the course of the activity consisting of three steps, the students exhibited different positioning and they are as follows: In the global warming modeling activity for Step 1, students were positioned as 'active learners', but at the same time, they showed a contradiction in being positioned as 'apprentice'. In the student-led research activities inherent to Step 2, they were positioned as 'scientists who design and conduct research' and 'bystanders' due to the controversial nature of SSI knowledge. As students participate in the social actions involved in Step 3, the position changed from 'elementary school students facing difficulty in making a change' to 'participatory citizens creating changes.' This study is significant because it shows students' potential to promote participatory and democratic citizenship through action-oriented SSI activities. In addition, pedagogical approaches were discussed dealing with the contradictions and limitations of positioning.