• Water for future
• /
• v.28 no.6
• /
• pp.147-158
• /
• 1995

The purpose of this study is to establish a method of estimating the daily urban water demand using statistical model. This method will be used for the development of the efficient management and operation of the water supply facilities. The data used were the daily urban water use, the population, the year lapse and the weather conditions such as temperature, precipitation, relative humidity, etc. Kwangju city was selected for the case study area. The raw data used in this study were rearranged either by month or by season for the purpose of analysis, and the statistical analysis was applied to the data to obtain the regression model. As a result, the multiple linear regression model was developed to estimate the daily urban water use based on the seather condition. The regression constant and the model coefficients were determined for each month of a year. The accuracy of the model was within 3% of average error and within 10% of maximum error. The developed model was found to be useful to the practical operation and management of the water supply facilities.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.4 no.3
• /
• pp.255-263
• /
• 2006

Vol-oxidizer is a device to convert $UO_2$ pellets into $U_3O_8$ powder and to feed a homogeneous powder into a Metal Conversion Reactor in the ACP(Advanced Spent Fuel Conditioning Process). In this paper, we propose a design model of the vol-oxidizer, develop the new vol-oxidizer with a capacity of 20 kg HM/batch in $UO_2$ pellets, and conduct a verification for the device. Design considerations include the internal structure, the capacity, the heating position of the device, and the size. The dimensions of the new vol-oxidizer are decided by the design model. We determine a permeability test of the $U_3O_8$ measuring the temperature distribution, and the volume of $UO_2$ and $U_3O_8$. We manufactured the new vol-oxidizer for a 20 kg HM/batch in $UO_2$ pellets, and then analyzed the characteristics of the $U_3O_8$ powder for the verification. The experimental results show that the permeability of the $U_3O_8$ throughout mesh enhance more than old vol-oxidizer, the oxidation time takes only 8 hours when compared with the 13 hours of the old device, and the average distribution of particle size is $40{\mu}m$. The capacities of new vol-oxidizer for a 20 kg HM/batch in $UO_2$ pellets were agree well with the predictions of design model.

• Journal of Bio-Environment Control
• /
• v.15 no.3
• /
• pp.257-263
• /
• 2006

This experiment was conducted to investigate the optimal media for 'Pechika' ever-bearing strawberry grown in hydroponic culture system in summer highland. Three mixed media (1:1, v/v) of peatmoss with perlite, rice hull, and granular rockwool, and four solution strengths of EC 0.5, 0.75, 1.0 and $1.25 dS{\cdot}m^{-1}$ were tested. Root zone temperature in peatmoss+perlite media was 1 to $3^{\circ}C$ lower than in the other media. The culture medium of mixing to peat moss and perlite was most effective in producing good yield and fruit quality. The culture medium of mixing to peat moss and perlite was the highest about 1,632kg/10a to yield yearly average, but was very undulating 732 kg/10a to yield in 2004 year and 3,013kg/10a in 2003 year. The deformed fruits were increased when the solution strength was increased, especially in EC $1.25dS{\cdot}m^{-1}$. The soluble solids and the acidity content of fruits were increased with higher solution strength regardless of media. The uptake of Ca and Mg was inhibited at higher solution strength, and the uptake of N, P and K was promoted. Therefore, the culture medium of mixing to peat moss and perlite was the most suitable culture medium to product strawberry in summer, because it had the highest yield even though fruit quality among treatments was not significant.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.13 no.4
• /
• pp.163-171
• /
• 1980

Recently, Bacillus has been identified as one of food poisoning bacteria especially in products of cereal foods in foreign countries. Therefore, the quantitative distribution of Bacillus cereus in market foods, its physiological characteristics, growth rate by temperature and heat resistance of its spore were examined. Thirty two samples of cooked rice, 20 samples of kimbab(cooked rice rolled with laver), 23 samples of rice cake, 13 samples of rice ana 13 samples of barley were collected from restaurents and food stores in Busan, Korea during the period from May to November in 1980. Forty samples of 101 samples submitted to the test appeared positive for Bacillus cereus showing abut $40\%$ in detection ratio. Detection ratio of Bacillus cereus was higher than $50\%$ in barley and rice, and about $30\%$ in rice products. Average Bacillus cereus content of in the samples was $2.6\times10^6/g$ in cooked rice, $2.3\times10^6/g$in kimbab, $4.9\times10^4/g$ in rice cake while that in rice and barley was about $10^3/g$. The result of biochemical tests of the bacterium was $100\%$ positive in catalase, egg yolk reaction, gelatin hydrolysis and glucose fermentation, $100\%$ negative in xylose, arabinose and mannitol oxidation, about $90\%$ positive in acetoin production, $80.0\%$ positive in nitrate reduction and citrate utilization and $55.0\%$ positive in starch hydrolysis test. Isolation ratio of Bacillus ceresus which showed haemolysis positive and starch hydrolysis negative results, was about $38\%$ in 40 strains examined. It is known that those strains has a close relation to food poisoning accident. Growth rate and generation time of Bacillus cereus isolated from the cooked rice were $0.34hr^{-1},\;2.02hr\;at\;20^{\circ}C,\;0.73hr^{-1},\;0.95hr\;at\;30^{\circ}C\;and\;0.49hr^{-1},\;1.44\;hr\;at\;40^{\circ}C$ respectively. Heat resistance value of Bacillus cereus spores suspended in phosphate buffer solution was $D_{90}=29.0min,\;D_{95}=8.7min,\;D_{98}=3.7\;min\;and\;D_{101}=2.3\;min(z=10.5)$.

• The Korean Journal of Pesticide Science
• /
• v.17 no.2
• /
• pp.94-106
• /
• 2013

The proficiency testing for the residue laboratories of pesticide registration was conducted in order to improve the reliability and the ability for pesticide residue analysis. On October 2011 the testing was carried out using the soil collected and kept as the moistened state for five years, which is expected to very low residue levels of pesticides. The soil was fortified with chlorpyrifos, metolachlor and procymidone in a manner similar to prepare soil sample for indoor soil degradation test, and then sub-samples were prepared for the distribution to participants. Some of them were randomly selected for confirm of homogeneity and to ensure the stability of samples at room temperature. Samples were consisted of two soil treated as different levels, one of which was used to the assesment and another used to confirm. In addition, provide three standard solutions, respectively concentration of 10 mg/L, and untreated soil. Forty seven institutions submitted results. The medians of results were used as the assigned values for pesticide residues. Fitness for purpose standard deviation of proficiency test was calculated by applying 20% RSD as the coefficient of variation allowed in the soil residue test. Z-score was applied for evaluation of individual pesticides, and the average of the absolute value of the Z-score for the overall assessment of pesticides. Laboratories evaluated the absolute value of the Z-score less than 2 to fit the case of chlorpyrifos and procymidone were 44, metolachlor 40.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.26 no.2
• /
• pp.141-149
• /
• 1993

The seasonal variation of lipid content was mostly attributed to diet, water temperature and period of reproduction etc. The lipid mainly consisted of neutral lipid and phospholipid. Nonpolar lipid content was higher in between late spring and summer, while polar lipid content lower during the period. The composition of neutral, glyco, and phospholipid of the total lipid: in average was 53.88, 10.09 and $36.03\%$, respectively. The neutral lipids were composed of triglycride($51.88\%$) and free sterol($23.21\%$) as major component and a little quantity of diglycerides, monoglycerides, esterified sterols and hydrocarbon, free fatty acid were also identified. The phospholipids of each fraction were mainly occupied by phosphatidyl choline($55.5\%$), followed by phosphatidyl ethanolamine($27.8\%$), phosphatidyl inositol($8.65\%$) and phosphatidyl serine($4.85\%$). The major fatty acids of the total lipid in ascidian were $C_{20:5},\;C_{22:6},\;C_{16:6}\;and\;C_{18:1}$, respectively. The fatty acid composition of phospholipid and neutral lipid showed a similar tendency to that of the total lipid. The major fatty acids in the fraction of glycolipid, however, appeared $C_{16:0},\;C_{20:1},\;C_{18:0}\;and\;C_{18:1}$ in order.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.17 no.3
• /
• pp.184-190
• /
• 1984

Sardine, Sardinops melanosticta, has been caught more than fifty thousand metric tons every year in adjacent sea of Korea, but most of them used for uneatable fish meal because of their rapid spoilage. Usually it is known that the main reason of putrefaction of foods is caused by the maicro-organisms included in them. Therefore, this experiment was carried out to identify the micro-organisms isolated from the intestine of fresh sardine and characterize their proteolytic enzymes produced from them. Aerobic cell count ranged from $1.7{\times}10^4\;to\;3.6{\times}10^5/g$, while anaerobic cell count, from $2.9{\times}10^4\;to\;5.5{\times}10^5/g$. Most of the isolated strains were psychrotrophic mesophiles. Among the two hundred and eighty strains isolated from the fresh samples, fifty-six strains ($20.0\%$) were proteolytics, one hundred and seventy-five strains ($62.5\%$) were lipolytics and tenty-nine strains ($10.5\%$) had the ability to produce hydrogn sulfide. The most predominantly isolated microbial groups from the fresh sardine were Moraxella ($31.4\%$) and Pseudomonas sup. ($28.6\%$). Flavobacterium-Cytophaga, Vibrio, Acinetobacter, Micrococcus spp. and Enterobacteriaceae appeared from $7.9\%\;to\;5\%$ out of total tested strains. The average bacterial count in the spoiled samples (stored at about $18^{\circ}C$ for 48 hours) was increased to the level of $2.9{\times}10^8/g$ for aerobes, $1.5{\times}10^8/g$ for anaerobes, then one hundred and ten strains, corresponding to $52\%$, out of two hundred and thirteen strains submitted to the test were proteolytics. The strongest proteolytic bacterium among the two hundred and eighty strains was identified as Pseudomonas 101 which grew best at $25^{\circ}C$. The optimum condition for the activity of the proteolytic enzyme produced by Pseudomonas 101 appeared $35^{\circ}C$ and pH 9.0, but the activity was relatively unchanged between 5.0 and 11.0 of pH and between $30^{\circ}C\;and\;50^{\circ}C$ of temperature.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.3 no.2
• /
• pp.79-89
• /
• 1995

Changes of microbial activity and physicochemical environment during composting of papermill sludge(PMS) in the pilot plant equipped with an agitated bed reactor were monitored for establishing the efficient composting system. Microbial activity determined as the evolution of $CO_2$ increased for the first 10 days after introduction of PMS to the reactor and decreased thereafter. Population changes of microorganisms in the reactor-PMS were not typical as in windrow system. The ratio of thermophilic bacteria to mesophilic bacteria, however, increased slowly even 23 days after introduction. Temperature of PMS increased rapidly from the first day and reached $62^{\circ}C$ at 7 days after introduction and decreased slowly thereafter. The acidity of PMS was pH 6.8 initially, increased to pH 8.0 after 7 days and decreased to pH 7.4 after 23 days. Redox potential(Eh) of PMS was -320mV at the beginning of composting, but it was increased with time to reach -15mV after 23 days composting. However, Eh of PMS pre-sterilized before measurement was average 50mV, regardless of composting periods indicating the major role of microorganisms during composting process. Water content of PMS was 67% initially and decreased to about 50% after 23 days composting in the reactor. Less than 13 days-old compost inhibited growth of radish in the container mixture with bed soil. Based on statistical analysis of microbial and physicochemical parameters of PMS during composting, an equation was developed for determining compost maturity. A number of experiments using various organic wastes are required before application of the formular to the practical use.

• Journal of Korea Water Resources Association
• /
• v.51 no.3
• /
• pp.247-261
• /
• 2018

The purpose of this study is to evaluate the groundwater level behavior of Geum river basin ($9,645.5km^2$) under future climate change scenario projection periods (2020s: 2010~2039, 2050s: 2040~2069, 2080s: 2070~2099) using SWAT (Soil and Water Assessment Tool). Before future evaluation, the SWAT was calibrated and validated using 11 years (2005~2015) daily multi-purpose dam inflow at 2 locations (DCD, YDD), ground water level data at 5 locations (JSJS, OCCS, BEMR, CASS, BYBY), and three years (2012~2015) daily multi-function weir inflow at 3 locations (SJW, GJW, BJW). For the two dam inflow and dam storage, the Nash-Sutcliffe efficiency (NSE) was 0.57~0.67 and 0.87~0.94, and the coefficient of determination ($R^2$) was 0.69~0.73 and 0.63~0.73 respectively. For the three weir inflow and storage, the NSE was 0.68~0.70 and 0.94~0.99, and the $R^2$ was 0.83~0.86 and 0.48~0.61 respectively. The average $R^2$ for groundwater level was from 0.53 to 0.61. Under the future temperature increase of $4.3^{\circ}C$ and precipitation increase of 6.9% in 2080s (2070~2099) based on the historical periods (1976~2005) from HadGEM3-RA RCP 8.5 scenario, the future groundwater level shows decrease of -13.0 cm, -5.0 cm, -9.0 cm at 3 upstream locations (JSJS, OCCS, BEMR) and increase of +3.0 cm, +1.0 cm at 2 downstream locations (CASS, BYBY) respectively. The future groundwater level was directly affected by the groundwater recharge by the future seasonal spatial variation of rainfall in the watershed.

• Korean Journal of Materials Research
• /
• v.11 no.8
• /
• pp.708-712
• /
• 2001

Microwave dielectric properties of $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb{2/3})_{1-x}Ti_x]O_3$ ceramics were investigated as a function of $Ti^{4+}$ content (0.05$\leq$x$\leq$0.35). A single perovskite phase was obtained from x=0.05 to x=0.15, and $TiO_2$ and $CaNb_2O^6$ were detected as a secondary phase beyond x=0.2. The structure was changed from orthorhombic at x=0.05 to cubic at x=0.35. Dielectric constant(K) was increased with increase of $Ti^{4+}$ content due to increase of rattling effect, and was inversely proportional to the cube of the average radius of B-site cation, however, Qf value was decreased, which was due to the decrease of grain size and the secondary phase. With the increase of $Ti^{4+}$ content, the temperature coefficient of resonant frequency(TCF) was controlled from -27.36 ppm/$^{\circ}C$ value to +18.4 ppm/$^{\circ}C$ value, which was caused by the influence of tolerance factor(t) and the bond valence of B-site. Typically, K of 51.67, Qf of 7268(GHz), TCF of 0 ppm/$^{\circ}C$ were obtained in the $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb_{2/3})_{0.8}Ti_0.2]O_3$ sintered at 13$50^{\circ}C$ for 3h.