• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.28-33
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• 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.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.747-752
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• 1999

The effects of nonpoint source pollutants from a small agricultural alluvial watershed on groundwater quality were investigated and analyzed in this study . Water quality factors of pH, electric conductivity(EC), total nitrogen(T-N), nitrate nitrogen(NO3-N), ammonium nitrate(NH4-N), and total phosphorus(T-P) concentrations were monitored at the watershed located in Shinbook-myon , Chunchon, Kangwon-Do, Korea for 2 years. Groundwater samples of about 2 liters from 7 to 20 farm wells were regulary collected and analyzed with respect to the water quality factors which were again anlayzed with respect to time and land uses of residential , agricultural , livestock feedlot, greenhouse, and natural areas.

• 한국환경보건학회지
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• 제41권5호
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• pp.305-313
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• 2015

Objectives: The objective of this study is to identify toxicants causing acute toxicity in effluents from the aluminum rolling industry that violate the discharge limits in Korea. Methods: Whole effluent toxicity tests (WET) were conducted on effluent discharged from the aluminum rolling industry following the US EPA WET test methods. We collected effluent samples three times and evaluated acute toxicity by using Daphnia magna. We employed toxicity identification evaluation (TIE) procedures to identify toxicants causing toxicity in the effluent. Results: No specific chemical groups were identified in the seven different manipulations applied to the of wastewater effluent samples showing 1.3 toxic units (TU) according to the TIE phase I procedures. Water quality parameters for water hardness, electric conductivity and heavy metals (Mn) were 4,322 mg/l as $CaCO_3$, 11.39 mS/cm, and $5,551{\mu}g/l$, respectively. Considering water hardness and reference toxicity, high concentrations of Mn can be disqualified from the causative toxicants. Consequently, high ionic concentrations of $Na^+$(1,648 mg/l), $Ca^{2+}$(1,048 mg/l), $Mg^{2+}$(1,428 mg/l) and $SO_4{^{2-}}$(7,472 mg/l) were identified to be causative toxicants. Water hardness and electric conductivity exceed the $EC_{50}$ value obtained by biological toxicity tests using Daphnia magna. Conclusion: According to TIE procedures, high salt concentration is determined to be a major toxicant in the effluent of agro-industrial wastewater treatment plants receiving wastewater from the aluminum rolling industry.

• 한국환경과학회지
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• 제24권1호
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• pp.17-23
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• 2015

This study was aimed to determine the effect of basal application of Effective Microorganisms (EM) on the grow and yield of cucumber. For treatments, the EM was applied to soil with fertilizer composed with $N-P_2O_5-K_2O$-manure (24.0-16.4-23.8-2,000kg) in the 1.0 strength (defined as EM+1S), 2/3 strength (defined as EM+2/3S), 1/2 strength (defined as EM+1/2S), without fertilizer (defined as EM), or only fertilizer in the 1.0 strength (defined as 1S). In result, there was no significant differences of organic substance content and pH with the EM treatment. While the EC (Electric conductivity) concentration was decreased, plant-available P (phosphorus) was markedly increased. Chlorophyll content was highest in the treatment of EM+standard application rate for both semi-forcing and retarding culture. In contrast, no significant difference was found in plant height and internode length under the fertilizer treatment. Weekly harvested number of cucumber was highest at the treatment of EM+standard application for the semi-forcing culture, while it was 3.6 at the EM+1/2 application for the retarding culture. Weekly yield was greatest at the EM+standard application treatment and decreased with the decrease of fertilizer application rate. In addition, weekly yield was significantly reduced in the treatment of EM. There was no significant difference in yields by production time with the fertilizer applications?. Yield was increased with temperature for the semi-forcing culture, while consistent pattern was maintained for the retarding culture.

• 생태와환경
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• 제43권4호
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• pp.459-470
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• 2010

In this study, we analyzed fish tolerance guilds in mainstems and tributaries of 65 streams and rivers arid their relations to water quality using dataset sampled from April to November, 2009. For the study, water quality parameters including biochemical oxygen demand (BOD), electric conductivity (EC), total nitrogen (TN), total phosphorus (TP), ammonia nitrogen ($NH_3$-N), nitrate nitrogen ($NO_3$-N) and phosphate phosphorus ($PO_4$-P) were analyzed in the laboratory and also tolerance ranges in 3 category fishes of sensitive, intermediate, and tolerant species with high abundance were analyzed. According to fish guild analysis, tolerant species was 58% of the total community and the proportion of omnivore species was 63% of the total, indicating a degradation of habitats and water quality. Water quality was shown typical longitudinal gradients from the headwater to the down-river; TN and TP increased toward the down-rivers except for the big point-source area and ionic contents, based on, electric conductivity showed same pattern. Tolerance guild analysis of 9 major species with high abundance indicated that sensitive groups had narrower tolerance range in the water quality than the groups of intermediate and tolerant species. In contrast, tolerant groups including Zacco platypus, Carassius auratus, and Opsarichthys uncirostris amurensis had wider tolerance ranges than the groups of sensitive and intermediate species. Thus, each group was evidently segregated from the tolerance levels. Principal Component Analysis (PCA) employed for the relations of water quality to fish species in each groups suggests that water quality had highest eigenvalues with fish species in the 1st axis of the PCA and nitrogen (TN, $NH_3$-N, $NO_3$-N) and phosphorus (TP) were key components differentiating three groups of sensitive, intermediate and tolerance guilds.

• 한국환경과학회지
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• 제13권2호
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• pp.161-165
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• 2004

This study has been conducted to develop a new recycling technology of sewage sludge using a carbonization process. The carbonizing yield, the calorific value and EC(electric conductivity) of carbonized sewage sludge had a tendency to be decreased with increase of the carbonizing temperature and time, but pH and the C/N were increased with increase the carbonizing temperature and time. The whole pore volume of carbonized sludge processed in the carbonizing furnace was /g, which was smaller than that in the electric furnace. But, the rates of mesopore and macropore were found to account for 100% therein. Rate of color and organic materials removal for dyeing wastewater were determined 70~97%, 78~83% on cotton yarn, 88~96%, 69~80% on wool wastewater and 77~89%, 77~87% on towel compared with powder activated carbon. Effect of carbonized sludge on chrysanthemum growth was investigated. Plant height and number of leaves was better mixture of carbonized sludge than comparison.

• Journal of Forest and Environmental Science
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• 제30권2호
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• pp.208-217
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• 2014

Leaf litter is the main and quick source of organic matter and nutrient to the soil compared to other parts of litter. This study focused on the nutrients (N, P and K) leaching from leaf litter of Melia azadirachta, Azadirachta indica, Eucalyptus camaldulensis, Swietenia macrophylla, Mangifera indica, Zizyphus jujuba, Litchi chinensis, Albizia saman, Artocarpus heterophyllus, Acacia auriculiformis, Dalbergia sissoo and Khaya anthotheca as the common cropland agroforest tree species of Bangladesh. About (9 to 35) % of initial mass was lost, while Electric Conductivity (EC) and TDS (Total Dissolved Solid) of leaching water increased to (573 to 3,247) ${\mu}S/cm$ and (401 to 2,307) mg/l respectively after 192 hours of leaching process. Mass loss (%) of leaf litter, EC and TDS of leaching water showed significant (ANOVA, p<0.05) curvilinear relationship with leaching time. Initial concentration of NH4, PO4 and K in leaching water was found to increase significantly (p<0.05) up to 48/72 hours and then remained almost constant at later stages (48/72 to 192 hours). Mass loss of leaves; EC, TDS, $NH_4$, $PO_4$ and K in leaching water was varied also significantly (ANOVA, p<0.05) among the studied tree species. All the tree species showed similar pattern of nutrients (K>N>P) release during the leaching process. The highest $NH_4$ (4,097 ppm) and potassium (8,904 ppm) concentration was found for M. azadirachta while the highest $PO_4$ (1,331 ppm) concentration was found for E. camaldulensis in the leaching water. Among the studied tree species, M. azadirachta, A. indica, D. sissoo, E. camaldulensis and Z. jujuba was selected as the best tree species with respect to nutrient leaching.

• Journal of Ecology and Environment
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• 제42권4호
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• pp.205-210
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• 2018

To assess the environmental factors determining the zonation between Phacelurus latifolius and Phragmites australis, vegetation survey and soil analysis were performed at a tidal marsh. The vegetation of the tidal marsh was classified into P. latifolius and Suaeda japonica dominated quadrats, P. latifolius and P. australis dominated quadrats, P. australis dominated quadrats, and P. australis and other land plants dominated quadrats. The density of P. latifolius ($83.7{\pm}5.5\;shoots\;m^{-2}$) was higher than that of P. australis ($79.3{\pm}12.1\;shoots\;m^{-2}$) in each dominated quadrat but height of two species were similar. Soil environmental characteristics of P. latifolius dominated quadrats appeared to be affected by tide based on higher soil electric conductivity ($EC_{PL}=1530{\pm}152{\mu}Scm^{-1}$ ; $EC_{PA+PL}=689{\pm}578{\mu}Scm^{-1}$ ; $EC_{PA}=689{\pm}578{\mu}Scm^{-1$) and lower pH ($pH_{PL}=5.96{\pm}0.16$ ; $pH_{PA+PL}=6.28{\pm}0.31$ ; $pH_{PA}=6.38{\pm}0.22$). In redundancy analysis, environmental characteristics of P. latifolius dominated quadrats and P. australis dominated quadrats were clearly separated and those of P. latifolius and P. australis co-dominated quadrats were similar to P. australis dominated quadrats. From our investigation, P. latifolius showed relatively high competitiveness when compared to P. australis in lower tidal zone rather than upper tidal zone. Zonation of P. latifolius and P. australis seems to be a transitional zone between halophytes and land plant species.

• 원예과학기술지
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• 제29권1호
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• pp.23-28
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• 2011

딸기에 적합한 수경재배기술을 개발하기 위하여, 배양액 농도와 뿌리의 활성과의 상관관계를 조사함으로써 딸기에 적정한 배양액의 농도를 구명하고자 하였다. '설향(雪香)' 딸기를 재료로 하여 야마자키 조성 딸기 전용배양액을 0.5, 1.0, $2.0dS{\cdot}m^{-1}$ 농도로 처리하였다. 그리고 투명 플라스틱 포트에 코코피트를 충진하고 처리별로 5주씩 정식하여 딸기의 지상부 및 뿌리의 발달을 관찰하였다. 뿌리의 활력은 TTC(Triphenyl-tetrazoliumchloride)법으로 조사하였다. 엽병장은 EC $1.0dS{\cdot}m^{-1}$ 처리구에서 가장 길었으며, 그 다음 EC 2.0, $0.5dS{\cdot}m^{-1}$ 순으로 나타났다. 엽폭은 EC $1.0dS{\cdot}m^{-1}$ 처리구에서 가장 넓었으며, EC 0.5, $2.0dS{\cdot}m^{-1}$ 순으로 나타났다. 과장, 과경, 과중 및 수량은 EC 0.5와 $1.0dS{\cdot}m^{-1}$ 처리구에서 EC $2.0dS{\cdot}m^{-1}$ 처리구 보다 통계적으로 유의하게 높게 나타났다. 그러나, 당도는 처리 간에 유의한 차이를 나타내지 않았다. 지상부 건물중은 EC $1.0dS{\cdot}m^{-1}$ 처리구에서 가장 높았으며 다음이 $0.5dS{\cdot}m^{-1}$ 처리구, $2.0dS{\cdot}m^{-1}$ 처리구 순으로 나타났다. 지하부의 건물중은 배양액의 농도가 0.5와 $1.0dS{\cdot}m^{-1}$에서 높게 나타났으며, $2.0dS{\cdot}m^{-1}$에서는 현저하게 낮았다. 배액의 산도 변화는 EC $1.0dS{\cdot}m^{-1}$ 처리구는 공급배양액의 pH와 비슷한 경향을 나타내었으나, EC 0.5 처리구에서는 상승하는 경향을 보였고 EC 2.0 처리구에서는 현저하게 낮아지는 경향을 보였다. Formazan의 농도는 EC $1.0dS{\cdot}m^{-1}$ 처리구에서 전 생육기간 동안 가장 높게 나타났으며, EC $2.0dS{\cdot}m^{-1}$ 처리구에서는 현저하게 낮은 경향을 보였다. 이상의 결과에서 '설향'딸기에 가장 적합한 배양액 농도는 EC $1.0dS{\cdot}m^{-1}$에 가까운 것으로 생각되었다. 또한, 배액의 pH는 뿌리의 활성과 직접적인 상관이 있어서, 배액의 pH가 높은 것은 뿌리의 활성이 양호한 것을 시사하고, 배액의 pH가 낮은 것은 뿌리의 활성이 낮은 것을 나타내는 지표가 될 수 있다는 것을 확인하였다. 이러한 결과는 딸기 수경재배에서 생육진단의 지표로 유용하게 활용될 수 있을 것으로 생각된다.

• Journal of Biosystems Engineering
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• 제22권4호
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• pp.469-478
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• 1997

This study was conducted to develop an automatic nutrient-solution mixing system for small-scale sewers. The nutrient-solution mixing system consisted of a low-cost and precise metering device and data acquisition ＆ control system with a personal computer. and, the metering device was composed of three parts those were supply pumps, metering cylinders and venturi tube. The system controlled electric conductivity(EC) and pH of nutrient-solution based on the time-based feedback control method with the information about temperature, EC, and pH of the nutrient-solution. The performance of the nutrient-solution mixing system was evaluated through the control of EC and pH while compared with those of commercial system. Also an experimental cultivation of tomato was conducted to verify and to improve the developed system. Results of this study were as follows. 1. The correlation coefficient of meteing device between the flow rate and operating time was 0.9999, and the linear reuession equation computed was y=21.759x, where y is the discharge($g$) and x is the operating time(s). 2. Calculated errors for the developed metering device and two commercial pump were $\pm$0.3% $\pm$2.45% and $\pm$1.38 % FS error respectively. 3. An automatic nutrient-solution mixing system based on a low-cost and precise metering device was developed. 4. The full scale errors of the developed system in controlling EC and pH at 23$\pm$1$^{\circ}C$ were $\pm$0.05mS/cm and $\pm$0.2, respectively 5. When using the commercial system, the controlled values of EC and pH of the 500 $\ell$ of water were 1.29 mS/cm and 6.1 pH for the setting points of 1.4 mS/cm and 6.0 pH respectively at 23$pm1^{\circ}C$. 6. The developed nutrient-solution control system showed $\pm$0.05 ms/cm of deviation from the setting EC value over the experimental cultivation period. 7. The deviation from the average values of Ca and Mg mass content in the several nutrient-solution were 0.5% and 1.8% respectively.