• Korean Journal of Organic Agriculture
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• v.17 no.3
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• pp.357-370
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• 2009

This experiment was conducted to investigate the effects of compost leachate and concentrated slurry on growth of tomato in hydroponic culture. In process of composting, compost leachate was produced water was through a saturated compost heap. The concentrated slurry was produced by filtration and concentration by membrane process. Filtration of pig slurry was necessary to prevent the hose clogging in hydroponics culture. The treatments of this experiment were consisted of seven different liquid fertilizers; compost leachate(CL), concentrated pig slurry (CS), compost leachate+byproduct(CL+BP), concentrated pig slurry+byproduct(CS+BP), compost leachate 50%+nutrient solution50%(CL+NS), concentrated pig slurry 50%+nutrient solution50%(CS+NS) and nutrient solution(NS) for tomato based on nitrogen content. The chemical nutrient solution was the solution of National Horticulture Research Station for the growth of tomato. The concentration of nutrient solution was adjusted a range of $1.6{\sim}2.0 mS/cm$ in EC. 1. The compost leachate and concentrated pig slurry were low in phosphorus(P), calcium(Ca), magnesium(Mg), but rich in potassium(K). 2. Plant height, SPAD value of tomato was highest in the plot of CS+NS, intermediate in CL, CS+BP, and lowest in 100% concentrated pig slurry. 3. The tomato yield of compost leachate plot was 91% compared with inorganic nutrient solution. The compost leachate solution could be used as a nutrition solution of tomato in organic hydroponics. 4. The growth including plant height, SPAD value, fruit number, fruit weight and yield of tomato in the CL 50%+NS 50% was similar in the control. In conclusion, the mixture solution of 50% pig slurry and 50% nutrient solution could be used as a nutrition solution of tomato hydroponic culture.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.2
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• pp.44-54
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• 1999

Agricultural water quality standards were reviewed through rice culture using treated sewage irrigation . The seqage from school building of Konkuk University was treated by a constructed wetland system, and theeffluent of the systeml was irrigated for rice culutre after nutrient concentration adjusted by dilution. Average concentration of COD, SS, T-N and T-P in irrigated water was 22.3mg/$\ell$, 6.5mg/$\ell$, 25.8 mg/$\ell$and 2.2mg/$\ell$, respectively. Treatment include irrigation of adjusted effluent with conventional fertilization (TWCF), adjusted effluent with no fertilization (TWNF). and effluent of the wetland system as it was with no fertilization (SWNF). These treatment plots were compared with control plot irrigated by tap water with conventional fertilization (CONTROL). Other environmentals for rice culture were identical for all the plots. Among them, TWCF showed the best growth rate and the highest yield, and constituents in the harvested rice showed not much difference among them. Which implies that irrigation with relatively high nutrient concentration compared to the current water quality standards may cause no adverse effect on rice culture and could be even beneficial . Although T-N for this study was 25 times greater than the current standards, rice culture wasnot adversely affected by irrigatino water quality and even beeter results were observed than the CONTROL. It could be mistakenly that clean irrigation water produces better agricultural product, however, it is not necessarily true. Irrigation water with moderate nutrient concentration can enhance the plant growth, and better result might be expected. Therefore, peer review and modification if necessary are needed to the current agricultural water quality standards, especially for the nutrient components.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.651-658
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• 2005

The Non-parametric Analysis is powerful in data test especially for the non- normality water quality data. The data at three monitoring stations of the Tam-Jin River were evaluated for their normality using Skewness, Q-Q plot and Shapiro-Willks tests. Various constituent of water quality data including temperature, pH, DO, SS, BOD, COD, TN and TP in the period of January 1994 to December 2004 were used as dataset. Shapiro-Willks normality test was carried out for a test 5% significance level. Most water quality data except DO at monitoring stations 1 and 2 showed that data does not normally distributed. It is indicating that non-parametric method must be used for a water quality data. Therefore, a homogeneity was conducted by Mann-Whitney U test (p<0.05). Two stations were paired in three pairs of such stations. Differences between stations 1, 2 and stations 1, 3 for pH, BOD, COD, TN and TP were meaningful, but Tam-Jin 2 and 3 stations did not meaningful. In addition, a narrow gap of the water quality ranges is not a difference. Categories in which all three pairs of stations (1 and 2, 2 and 3, 1 and 3) in the Tam-Jin River showed difference in water quality were analyzed on TN and TP. The results of in this research suggest a right analysis in the homogeneity test of water quality data and a reasonable management of pollutant sources.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.741-749
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• 2008

Many small-scale ponds that serve as ecological habitat, recreation and irrigation are faced to eutrophication problem, which causes aesthetic nuisance and ultimately loss of their functions. Thus accurate evaluation of the trophic state of these ponds is essential to provide rational information to the stakeholders so that they can develop effective management actions. In this study, the trophic state of a small pond (Wonheung) that experiencing water quality degradation due to vicinity land development was assessed using various Trophic State Indexes (TSIs) and statistical analysis including Principal Components Analysis (PCA) based on the field monitoring data obtained from May to December, 2007. The results showed that the pond is under eutrophic state with average total nitrogen (T-N) and total phosphorus (T-P) concentrations of $708.1{\mu}g/L$ and $59.3{\mu}g/L$, respectively. The factor loading plot obtained from PCA showed distinct two influencing factors, PC 1 and PC 2. PC 1 was grouped by T-P, Chlorophyll a (Chl-a), suspended solids (SS), TN/TP ratio, and transparency that all strongly related to the eutrophication state, while PC 2 by temperature, conductivity, dissolved oxygen (DO) and turbidity that explains the seasonal water quality variations. The limiting factor was identified as light rather than phosphorus by both T-N/T-P ratio and TSI indexes analysis. The results and methodology adopted in this study can be used for water quality assessment for other small ponds and lakes.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.29-37
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• 2011

Effect of rice straw mat and wood shaves on the reduction of runoff and nonpoint source (NPS) pollution loads from field plots were experimentally studied. Three runoff plots of $5{\times}22$ m in size and 3 % in slope were prepared on a loamy sand field. Each plot was equipped with a flume to measure runoff and collect water samples. Experimental treatments of surface cover were bare, wood shaves (1,000 kg/ha) and rice straw mat cover (3,000 kg/ha). Under radish was cultivation. During the growing season of the radish, three rainfall-runoff events were monitored. Effect of wood shaves and straw mat cover on runoff reduction was 4~30 % and 33~75 % respectively compared to control. The effect on NPS pollution reduction was 36.8 and 64.3 % in BOD, 41.1 and 80.8 % in SS, 34.0 and 56.1 % in TP and 28.0 and 56.6 % in TN respectively. It was analyzed that the reduction of runoff and NPS pollution were mainly contributed by the decrease of rainfall energy impact and flow velocity and the increase of infiltration due to the surface cover materials. Rice straw mat showed very stable soil cover while large portion of wood shaves were lost during heavy storm events. It was concluded that straw mat was an efficient cover material to reduce NPS pollution from upland fields.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.37-44
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• 2013

We have examined the effect of rice straw mat (RSM) on the reduction of non-point source (NPS) pollution loads at soybean cultivations. The slope of the experimental plot was about 3 %. Monitoring was carried out for four years at conventional tillage (CT) in 2008~2009 years and RSM covered tillage in 2010~2011 years. Thirty-two rainfall events were monitored and analyzed during the study period. During the 2 years of 2008 and 2009, 20 rainfall runoff events were monitored. But in 2010 years, only 2 rainfall runoff events could be monitored. And in 2011 years, 10 rainfall runoff events was monitored. It was because the RSM cover enhanced infiltration and reduce runoff in 2010 and 2011. Average NPS pollution load (organic matters) of the RSM covered field was reduced by 72.1~94.2 % compared to that of CT field. NPS pollution load of TN and TP reduced by 67.5 % and 55.7 %, respectively. Especially, SS pollution load was reduced by 97.3 %. Based on the results, rice straw mat cover was considered as a promising best management practices (BMP) to reduce NPS pollution load. However, it was recommended that the results are limited to the field conditions and the same experiments must be performed on different soil textures, slopes, and crops if it is applied to the development of policies.

• Journal of The Korean Society of Grassland and Forage Science
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• v.26 no.4
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• pp.293-300
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• 2006

This study was carried out to determine the effect of chemical fertilizer and two fermented types of pig slurry on the dry matter(DM) yield of three crops and chemical properties. The experiment design was a split plot with three replications. Main plots consist of three crops : $sorghum{\times}sudangrass$ hybrid('SS405'), sudangrass('Jumbo'), corn('DK501'). Sub plots consist of three treatments : chemical fertilizer (CF N-200, P-150, K-150 kg/ha), aerobic fermented pig slurry (APS 200kg N/ha), and aerobic fermented pig slurry treated with probiotics (APS+P 200 kg N/ha). Plant heights with three crops per sudangrass (380.3cm) was the longest (p<0.01). Dry matter yield of aerobic fermented pig slurry treated with probiotics was the highest the other treatments (p<0.01). Crude protein (CP) content were highest in $sorghum{\times}sudangrass$ hybrid than in the other crops. Cupper content(%) were highest in aerobic fermented pig slurry treated with probiotics than in the other treatments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.1
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• pp.1-11
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• 1986

Welded connectors of the cover plates, the transverse stiffeners of the plate girders, and the gusset plates of the plates girders or box girders, were selected as studying objects. A simplified method of drawing the S-N curves in these welded joints by a computer program without the direct fatigue tests was established. The plots on the S-N curve using the values from the practical fatigue tests were compared with the results from the method of the computer programming. The results of these studies are as follows. It appeared that the fatigue life by calculation method was a little less than the practical fatigue life from the actual tests. The latter values included both life $N_c$ of occurrence of initial crack $a_i$ and the life $N_p$ of propagation of critical crack. On the other hand, the former values included only the life $N_p$. Therefore, these results should be considered as justifiable ones. Since the difference between the two results was not significant, the results by calculation method should be in the conservation side when the safety of the structures was considered. Consequently, the results by calculation method should be applicable to the fracture fatigue design of structure. For reference, the same fatigue tests were performed with the specimens of 3 pieces in each case made of the low-strength steel, SS 41. The results went unexpected showing that the fatigue strength was lower in the case of low-strength steel. That is, in the case of the cover plate, the fatigue strength became slowly higher than the case of high-strength steel, SWS 50. That was observed when the maximum testing stress was higher than $14kg/mm^2$. In addition, in the case of the transverse stiffener, the fatique strength became rapidly higher than the case of SWS 50. That was observed when the maximum testing stress was lower than $31kg/mm^2$. It was thought that more such fatigue tests should be performed for more reliable results.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.112-121
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• 2004

A study was performed to examine the effects of UV-disinfected reclaimed water on microorganism concentration during rice culture. Four treatments were used and each one was triplicated to evaluate the changes of microorganism concentrations: stream water irrigation (STR), biofilter effluent irrigation (BE), UV-disinfected water irrigation with dose of 6 mW ${\cdot}$ s $cm{-2}$ (UV-6), and UV-disinfected water irrigation with dose of 16 mW ${\cdot}$ s $cm{-2}$ (UV-16). The indicator microorganisms of interest were total coliform (TC), fecal coliform (FC), and E. coli. The biofilter effluent from 16-unit apartment sewage treatment plant was used as reclaimed water and flowthrough type UV-disinfection system was used. Concentrations of indicator microorganisms in the treatment plots ranged from $10^2$ to $10^5$ MPN/100 mL during 24 hours after irrigation in May and June, where initial irrigation water for transplanting reparation was biofilter-effluent without UV-disinfection. It implies that initial irrigation using only non-disinfected reclaimed water for puddling in paddy field can be health-concerned because of more chance of farmer's physical contact with elevated concentration of microorganisms. The concentrations of microorganisms varied widely with rainfall, and treatments using UV-disinfected water irrigation showed significantly lower concentrations than others and their levels were within the range of paddy rice field with normal surface water irrigation. The mean concentrations of STR and BE during growing season were in the range of 4 ${\times}\;10^3$ MPN/100 mL for TC, and 2${\times}\;10^3$ MPN/100 mL for FC and E, Coli, While mean concentrations of UV-S and UV-lS were less than 1${\times}\;10^3$ MPN/100 mL for all the indicator microorganisms. Overall, UV-disinfection was thought to be feasible and practical alternative for agricultural reuse of secondary level effluent in Korea.