• Korean Journal of Environmental Agriculture
• /
• v.39 no.4
• /
• pp.327-333
• /
• 2020

BACKGROUND: Through Saemangeum development project, 283 ㎢ of new land is planned to be created and the reclaimed land of 89.7 ㎢ will be used as agricultural land. Therefore, monitoring of soil salinity is required to evaluate the suitability of the land for agricultural purposes. METHODS AND RESULTS: We investigated changes of soil physico-chemical properties, including electric conductivity (EC), of the Saemangeum reclaimed tidal land (1,195 ha) from 2008 to 2017 to obtain basic data for suitable soil management of the Saemangeum reclaimed tidal land. Soil samples were collected from the sites spaced 200 meters apart from each other. Soil analysis results showed that average soil EC was 14.5 dS m-1 in 2008, and decreased to 6.5 dS m-1 in 2014 and to 0.9 dS m-1 in 2017. Accordingly, the soil area below soil EC 4.7 dS m-1 (accepted as farmable soil salinity) increased; 25.0% in 2008, 54.3% in 2014, and 96.9% in 2017. The annual decrease in soil EC was described as y = -1.5756x + 14.6 (R2= 0.96), where y = soil EC and x = elapsed years since 2008. CONCLUSION: The soil salinity have decreased to a level for cultivation of most edible crops. However, since the soil chemical properties, such as soil organic matter were inadequate for the cultivation of crops, it was suggested that management of soil fertility would be important for efficient agricultural use of Saemangeum reclaimed land.

• Journal of Korean Society of Forest Science
• /
• v.108 no.2
• /
• pp.241-258
• /
• 2019

The aim of this study was to analyze the factors that affect the habitat of fishes and amphibians in a mountain stream that is part of an experimental forest at Kongju National University, Gongju, Chungcheongnam, Korea, and examine the differences in the presence of fishes and amphibians in the stream before and after construction of an erosion control dam. The results showed that the factors that affect the presence of fishes are pH, electrical conductivity (EC), dissolved oxygen (DO), flow velocity, and step-pool number, and that the factors that affect the presence of amphibians are monthly rainfall, pH, EC, DO, and crown density. Of these factors, pH, EC, flow velocity, and monthly rainfall were significantly different before and after dam construction; however, the differences among the other three factors from dam construction, except EC, might not have been enough to affect the presence of fishes and amphibians. Our results suggest that the difference in the frequency of fishes and amphibians surveyed before and after dam construction in the upper and lower stream sections were not statistically significant. One exception to this was the presence of amphibians in the lower stream section during and after dam construction, which could have been the result of a large amount of sediment produced by excavation that led to high EC.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.15 no.1
• /
• pp.159-170
• /
• 2007

Organic compost from the food waste and poultry manure is useful for a soil conditioner and fertilizer. The purpose of this study is to compare the effect of the food waste compost(FC) and poultry manure compost(PC) separately on the growth of young radish and the change of soil properties. Applying 3, 6, $9kg/m^2$ of FC and 1, 2, $3kg/m^2$ of PC, the cultivation of young radish was carried out in the crop field. In young radish applied with FC, leaf length was positively increased with the increasing usage of the compost. Number and area of leaves, and weight of leaf and root were peaked at applying rate of $6kg/m^2$. Growth of young radish with FC of $9kg/m^2$ was lowest in the initial period of the cultivation, and it is regarded that the applying rate of $9kg/m^2$ was detrimental to the germination of the young radish. In young radish applied with PC, the growth rate lowest at applying of $2kg/m^2$ than any other applying rate. Soil properties as bulk density and EC were considerably improved according to applying of food-waste and poultry manures compost. It should be considered to be needed additional study about the accurate applying rate and detailed investigation for soil properties.

• Journal of Environmental Science International
• /
• v.20 no.11
• /
• pp.1447-1455
• /
• 2011

The purpose of this study was to analyze physicochmical characteristics of oil within planting base of Incheon coastal reclamation cities where 10 years have passed since reclamation, and to provide basic data to promote growth and development of plants by conducting evaluation based on the planting degree standard. Study targets were Cheongra, Sondo, and Yeongjong districts within Incheon Free Economic Zone, the coastal reclamation city. The analysis results of average soil characteristics of 3 districts. Soil acidity(pH) was shown in orders of Cheongra district(8.85) > Songdo district(8.70) > Yeongjong district(7.97) and electric conductivity(EC) was shown in orders of Cheongra district(4.80 dS/m) > Songdo district(1.30dS/m) > and Yeongjong district(0.07 dS/m). Organic matter content(OMC) was shown in orders of Cheongra district(5.72%) > Songdo district(2.60%) > Yeongjong district(0.59%) and available phosphate was shown in orders of Cheongra district(70.70 mg/kg) > Songdo district(23.07 mg/kg) > Yeongjong district(2.49 mg/kg). $K^+$ was shown in orders of Songdo district(0.84 cmol/kg) > Cheongra district(0.74 cmol/kg) > Yeongjong district(0.22 cmol/kg), $Ca^{++}$ was shown in orders of Cheongra district(22.08 cmol/kg) > Songdo district(9.87 cmol/kg) > Yeongjong district(4.04 cmol/kg), and $Mg^{++}$ was shown in orders of Cheongra district(1.98 cmol/kg) > Songdo district(1.22 cmol/kg) > Yeongjong district(1.12 cmol/kg). Planting base level of coastal reclaimed land can be applied with above intermediate level, soil acidity and available phosphate were all more than intermediate in 3 districts, and electric conductivity was low level in Cheongra district and more than intermediate level in Songdo and Yeongjong districts. Organic matters content was more than intermediate level in Cheongra district and low level in Songdo and Yeongjong district. $K^+$ among exchangeable ions was intermediate level in Cheongra and Songdo districut and low in Yeongjong district. $Ca^{++}$ and $Mg^{++}$ both were more than imtermidiate levels in 3 districts.

• Korean Journal of Ecology and Environment
• /
• v.43 no.2
• /
• pp.338-344
• /
• 2010

The automatic water quality monitoring system (AWQMS) have been installed to immediately response to any pollution incident. It also make it possible to conduct the task efficiently regarding water quality control. The purpose of this study is to enhance reliability by securing accuracy of automatic water quality data through quality assessment (QA) for temperature, pH, dissolved oxygen (DO), electric conductivity (EC), total organic carbon (TOC). The result of comparison between manual and automatic data, relative accuracy of general items (temperature, pH, EC, DO) and TOC were mostly satisfied with guideline (i.e. less than 20%). On the other hand, relative accuracy of DO between sampling site and housing site was somewhat against the guideline. The contamination by attaching algae and microorganism in the pipeline is considered as main cause. After backwashing the pipeline, DO concentration was increased up to 53%. Therefore, pipeline management is recognizable as important thing to secure reliability of water quality data.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.676-683
• /
• 2003

A laboratory experiment using artificial fracture rocks was used to understand the 3-dimensional dispersion of a tracer and the mixing process in a fractured network. In this experiment, 12cm polystyrene foam cubes with two electrodes for monitoring electric conductivity (EC) were used as artificial fractured rocks. Distilled water with 0.5mS/m was used as a tracer in water with 35mS/m and the difference of EC between the tracer and the water was monitored by a multipoint simultaneous measurement system of electrical resistance. The results showed that even if the fracture arrangement pattern was not straight in the direction of the flow, the tracer did not diffuse along individual fractures and an oval tracer plume, which was the distribution of tracer concentrations, tended to be form in the direction of the flow. The vertical cross section of the tracer distribution showed small diffusivity in the vertical direction. The calculated total tracer volume passing through each measurement point in the horizontal cross section showed while that the solute passed through measurement points near the direction of hydraulic gradient and in other directions, the passed tracer volumes were small. Using Peclet number as a criterion, it was found that the mass distribution at the fracture intersection was controlled in the stage of transition between the complete mixing model and the streamline routing model.

• Applied Chemistry for Engineering
• /
• v.17 no.3
• /
• pp.243-249
• /
• 2006

Porous polymer gel electrolytes (PGEs) based on poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) as a polymer matrix and polyvinylpyrolidone (PVP) as a pore-forming agent were prepared and electrochemical properties were investigated for an electric double layer capacitor (EDLC) in order to increase a permeability of an electrolyte into the PGE. Propylene carbonate (PC) and ethylene carbonate (EC) as plasticizers, and tetraethylammonium tetrafluoroborate ($TEABF_4$) as a supporting salt for the PGE were used. EDLC unit cells were assembled with the PGE and electrode comprising BP-20 and MSP-20 as activated carbon powders, Super P as a conducting agent, and P(VdF-co-HFP)/PVP as a mixed binder. Ion conductivity of PGEs increased with an increased PVP content and was the best at 7 wt% PVP, whereas electrochemical characteristics such as AC-ESR of unit cell were better in 3 wt%. And electrochemical characteristics of the unit cell with PGE were the best at a 33 : 33 weight ratio of PC to EC. Specific capacitance of a mixed plasticizer system of PE and EC was higher than that of pure PC. Ion conductivity of PGEs with a film thickness of $20{\mu}m$ was higher, but electrochemical characteristics of unit cells were higher for a $50{\mu}m$ membrane thickness. Also, the unit cell has shown the highest capacitance of 31.41 F/g and more stable electrochemical performance when PGE and electrode were hot pressed. Consequently, the optimum composition ratio of PGE for EDLCs was 23 : 66 : 11 wt% such as P(VdF-co-HFP) : PVP = 20 : 3 wt% and PC : EC = 44 : 22 wt%. In this case, $3.17{\times}10^{-3}S/cm$ of ion conductivity was achieved at the $50{\mu}m$ thickness of PGE for EDLCs. And the electrochemical characteristics of unit cells were $2.69{\Omega}$ of DC-ESR, 28 F/g of specific capacitance, and 100% of coulombic efficiency.

• Agricultural and Biosystems Engineering
• /
• v.4 no.2
• /
• pp.45-49
• /
• 2003

Achievements in the real-time soil spectro-photometer are: an improved soil penetrator to ensure a uniform soil surface under high speed conditions, real-time collecting of underground soil reflectance, getting underground soil color images, use of a RTK-GPS, and all units are arranged for compactness. With the soil spectrophotometer, field experiments were conducted in a 0.5 ha paddy field. With the original reflectance, averaging and multiple scatter correction, Kubelka-Munk (KM) transformation as soil absorption, its 1st and 2nd derivatives were calculated. When the spectra was highly correlated with the soil parameters, stepwise regression analysis was conducted. Results include the best prediction models for moisture, soil organic matter (SOM), nitrate nitrogen ($NO_3-N$), pH and electric conductivity (EC), and soil maps obtained by block kriging analysis.

• Proceedings of the Korean Society for Bio-Environment Control Conference
• /
• 2004.03a
• /
• pp.196-203
• /
• 2004

• Journal of Animal Environmental Science
• /
• v.4 no.2
• /
• pp.183-191
• /
• 1998

This study was carried out to elucidate the correlation between Germination Index(G.I.) and CO2 emission for evaluation of the maturity of compost products. 13 compost samples was used for this experiment. The G.I. test was carried out on the basis of T-N 200ppm. As a result of this research, we found that CO2 emission method was good simple indicator for evaluation of maturity of compost materials, in spite of G.I. The obtain results are summarized as follows ; 1. The correlation value between the G.I. and the CO2 emission was R2 = 0.776. 2. The correlation value between EC(Electric Conductivity) and G.I. was R2 =0.7. 3. The equation calculated from G.I. and CO2 emission was G.I. = -16.7(InCO2) - 6.87. 4. From these results, we found the possibility of estimation for the value of G.I.(T-N 200ppm) from CO2 emission volume under specific condition.