• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.162-173
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• 2009

Information on the expected geographical shift of suitable zones for growing crops under future climate is a starting point of adaptation planning in agriculture and is attracting much concern from policy makers as well as researchers. Few practical schemes have been developed, however, because of the difficulty in implementing the site-selection concept at an analytical level. In this study, we suggest site-selection criteria for quality Fuji apple production and integrate geospatial data and information available in public domains (e.g., digital elevation model, digital soil maps, digital climate maps, and predictive models for agroclimate and fruit quality) to implement this concept on a GIS platform. Primary criterion for selecting sites suitable for Fuji apple production includes land cover, topography, and soil texture. When the primary criterion is satisfied, climatic conditions such as the length of frost free season, freezing risk during the overwintering period, and the late frost risk in spring are tested as the secondary criterion. Finally, the third criterion checks for fruit quality such as color and shape. Land attributes related to these factors in each criterion were implemented in ArcGIS environment as relevant raster layers for spatial analysis, and retrieval procedures were automated by writing programs compatible with ArcGIS. This scheme was applied to the A1B projected climates for South Korea in the future normal years (2011-2040, 2041-2070, and 2071-2100) as well as the current climate condition observed in 1971-2000 for selecting the sites suitable for quality Fuji apple production in each period. Results showed that this scheme can figure out the geographical shift of suitable zones at landscape scales as well as the latitudinal shift of northern limit for cultivation at national or regional scales.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.143-149
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• 2019

This study was conducted to investigate the graft-taking and growth of grafted cucumber seedlings as affected by light quality and blink cycle of LED modules. Four light quality treatments, namely blue, red, blue+red, white LED and four blink cycle levels of 5s/5s, 7s/3s, 9s/1s and control were provided to investigate the effect of lighting quality and blink cycle on the graft-taking and growth of grafted cucumber seedlings. Photoperiod for the control was 12/12 h. Photosynthetic photon flux, air temperature, and relative humidity for healing were maintained at $100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $25^{\circ}C$, and 90%, respectively. There was no significant difference in graft-taking of grafted cucumber seedlings according to light quality except the blue LED with the blink cycle of 5s/5s. Regardless of the blink cycle, there was no significant difference in graft-taking of cucumber seedlings healed under red, blue+red, and white LED modules. These results implied that the effects of light quality and blink cycle on the graft-taking were not significant. Differences in the leaf length, leaf area, and fresh weight of cucumber seedlings healed blue or red LED with the blink cycle of 9s/1s were found to be significant. There was no significant effect of the blink cycle on the growth of cucumber seedlings healed under white LED modules. The prices of white LED are gradually falling due to increased demand. Considering the manufacturing unit price of white LED modules, the cost savings of 10-15% are expected as compared to the conventional blue/red LED modules. Therefore, it was concluded that the use of white LED modules will be economical as an artificial lighting sources for healing of grafted seedlings.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.8-14
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• 2023

This study was conducted to develop a precision automatic irrigation system in a nursery by considering the problems and improvements of manual and the conventional automatic irrigation system. The amount of irrigated water between the conventional automatic irrigation system and manual irrigation was 28.7 ± 4.4 g and 14.2 ± 4.3 g, respectively, and the coefficient of variation was less than 30%. However, the coefficient of variation of the conventional automatic irrigation system of 15%, was higher than that of manual irrigation of 30%. The irrigation test using the developed uniform irrigation system attached with the nozzle of a spray angle 80° and most highest uniformity was at height 600 mm. And coefficient of variation of the irrigation uniformity at the center part was within 20%, but irrigation amount of the edge part was lower 50% and over compared to the center part. As a result of a tomato grafting seedling cultivation test using the developed uniform irrigation system, the average plant height of seedling at the edge part was 28 mm but plant height at the center part was higher as 72 mm. Therefore, it was necessary to apply additional irrigation device at the edge part. The irrigation uniformity of the edge concentrated irrigation system was investigated that the irrigation amount of the edge part was irrigated by more than 50% compared with the center part, and coefficient of variation of the irrigation amount at the center part was less than 30%. As a result of a cucumber grafting seedling cultivation test using the edge concentrated irrigation system, the plant height of seedlings in the edge and central part of cultivation bed were 24% and 26%, respectively, so irrigation uniformity was higher then the uniform irrigation system. In order to improve the uniformity of seedlings, it is necessary to adjust the height of boom according to the growth of the seedling by installing a distance sensor in the overhead watering and boom irrigation system.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.57-71
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• 2015

This study was conducted to develop the fertigation system with a peristaltic hose pump and brushless DC motor. The fertigation system was consisted of sensor, main controller, motor control unit, peristaltic pump, water supply pump, control panel, and filter. The peristaltic pump discharges liquid by squeezing the tube with rollers. Rollers attached to the external circumference of the rotor compresses the flexible tube. The fluid is contained within a flexible tube fitted inside a circular pump casing. The developed fertigation system has no mixing tank but instead injects directly a concentrated nutrient solution into a water supply pipe. The revolution speed of the peristaltic pump is controlled by PWM (Pulse width modulation) method. When the revolution speed of the peristaltic pump was 300rpm, the flow rate of the 3.2, 4.8, 6.3mm diameter tube was 202, 530, 857mL/min, respectively. As increasing revolution speed, the flow rate of the peristaltic pump linearly increased. As the inner diameter of a tube larger, a slope of graph is more steep. Flow rate of three roller was more than that of four roller. Flow rate of a norprene tube with good restoring force was more than that of a pharmed tube. As EC sensor probe was installed in direct piping in comparison with bypass piping showed good performance. After starting the system, it took 16~17 seconds to stabilize EC. The maximum value of EC was 1.44~1.7dS/m at a setting value of 1.4dS/m. The developed fertigation system showed ±0.06dS/m deviation from the setting value of EC. In field test, Cucumber plants generally showed good growth. From these findings, this fertigation system can be appropriately suitable for fertigation culture for crops.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.274-281
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• 2015

BACKGROUND: A lasting release of low levels of persistence chemicals including pesticides and pharmaceuticals into river has a bad influence on aquatic ecosystems and humans. The present study monitored pesticide residues in the Yeongsan and Seomjin river basins and their tributaries as a fundamental study for water quality standard of pesticides.METHODS AND RESULTS: Nine pesticides(aldicarb, carbaryl, carbofuran, chlorpyrifos, 2,4-D, MCPA, methomyl, metolachlor, and molinate) were determined from water samples using SPE-Oasis HLB(pH 2) and LC/MS/MS. Validation of the method was conducted through matrix-matched internal calibration curve, method detection limit(MDL), limit of quantification(LOQ), accuracy, precision, and recovery. MDLs of all pesticides satisfied the GV/10 values. Linearity(r²) was 0.9965- 0.9999, and a percentage of accuracy, precision, and recovery was 89.4-113.6%, 3.1-14.0%, and 90.8-106.2%, respectively. All pesticides exclusive of aldicarb were determined in the river samples, and there was a connection between the positive monitoring results and agricultural use of the pesticides.CONCLUSION: Monitoring outcomes of the present study implied that pesticides were a possible non-point pollutant source in the Yeongsan and Seomjin river basins and tributaries. Therefore, it is required to produce and accumulate more monitoring results on pesticides in river waters to set water quality standards, finally to preserve aquatic ecosystems.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.363-373
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• 2010

"Curve number" (CN) indicates the runoff potential of an area. The US Soil Conservation Service (SCS)'s CN method is a simple, widely used, and efficient method for estimating the runoff from a rainfall event in a particular area, especially in ungauged basins. The use of soil maps requested from end-users was dominant up to about 80% of total use for estimating CN based rainfall-runoff. This study introduce the use of soil maps with respect to hydrologic and watershed management focused on hydrologic soil group and a case study resulted in assessing effective rainfall and runoff hydrograph based on SCS-CN method in a small watershed. The ratio of distribution areas for hydrologic soil group based on detailed soil map (1:25,000) of Korea were 42.2% (A), 29.4% (B), 18.5% (C), and 9.9% (D) for HSG 1995, and 35.1% (A), 15.7% (B), 5.5% (C), and 43.7% (D) for HSG 2006, respectively. The ratio of D group in HSG 2006 accounted for 43.7% of the total and 34.1% reclassified from A, B, and C groups of HSG 1995. Similarity between HSG 1995 and 2006 was about 55%. Our study area was located in Sosu-myeon, Goesan-gun including an approx. 44 $km^2$-catchment, Chungchungbuk-do. We used a digital elevation model (DEM) to delineate the catchments. The soils were classified into 4 hydrologic soil groups on the basis of measured infiltration rate and a model of the representative soils of the study area reported by Jung et al. 2006. Digital soil maps (1:5,000) were used for classifying hydrologic soil groups on the basis of soil series unit. Using high resolution satellite images, we delineated the boundary of each field or other parcel on computer screen, then surveyed the land use and cover in each. We calculated CN for each and used those data and a land use and cover map and a hydrologic soil map to estimate runoff. CN values, which are ranged from 0 (no runoff) to 100 (all precipitation runs off), of the catchment were 73 by HSG 1995 and 79 by HSG 2006, respectively. Each runoff response, peak runoff and time-to-peak, was examined using the SCS triangular synthetic unit hydrograph, and the results of HSG 2006 showed better agreement with the field observed data than those with use of HSG 1995.

• Journal of Wetlands Research
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• v.14 no.1
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• pp.59-73
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• 2012

The importance of rice paddy wetland has been raised since the 10th Ramsar Convention in 2010. However, there is shortage of study on the evaluation of rice paddy wetland and also of the study on the effect of organic agriculture on the vegetation characteristics. Accordingly, this study examined the vegetation characteristics of organic rice paddy for the basic resources of evaluating value of rice paddy wetland. 6 places of organic rice paddy and conventional rice paddy were chosen as research targets. It analyzed the function of 'Floral Diversity and Wildlife Habitat' among the revised RAM, an existing wetland evaluation system. As to the factor affecting the analysis result, simple land-use result was proved to determine the evaluation. As a result of vegetation investigation total 176 taxa, 53 families, 146 generics, 148 species, 26 varieties and 1 forma. When the difference of appearance of life form between organic area and conventional area was examined, organic paddy had higher appearance of life form in Therophyte and Megaphanerophyte. For the distribution of Naturalized plants, organic rice paddy had lower naturalized rate and urbanization index than conventional rice paddy. As to the Pearson correlation analysis between growing condition and vegetation characteristics, variety of rice paddy vegetation showed it was not heavily influenced by the land use. However, the organic rice paddy area had more variety in vegetation than conventional rice paddy. There was about 1% correlation with types of Cyperaceae, which means that the classification group of Cyperaceae can be utilized in evaluating rice paddy wetland later on. It is determined that the wetland evaluation has been widely influenced by soil environment, water environment and surrounding natural and artificial landscape as well as vegetation characteristics. Accordingly, further research seems to be required with minute investigation to an extensive area.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.335-342
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• 2013

Sophorae radix extract (SRE) has been registered as an environment-friendly organic material that is widely used in the cultivation of crops in Korea. Matrine, the active ingredient in SRE, was reported as a toxic substance in the nervous system in mice. However, no information is available on its toxic effects in other organisms. Therefore, antimutagenicity and two kinds of genotoxicity tests (bacterial reverse mutation and chromosome aberration test) of two samples of SRE were investigated in this study. Antimutagenicity test was experimented by using bacterial reverse mutation test. In the reverse mutation test, Salmonella Typhimurim TA98, TA1535 and TA1537 were used to evaluate the mutagenic potential of SRE. Bacterial reverse mutation test was also performed on positive and negative control groups in the presence of the metabolic activation system (with S-9 mix) and metabolic non-activation system (without S-9 mix). In the chromosome aberration test, Chinese hamster lung cells were exposed to SRE for 6 or 24 hours without S-9 mix, or for 6 hours with S-9 mix. Negative and positive control groups were experimented for chromosome aberration test. As a result, the number of mutated colonies induced by 4-NQO were reduced by SRE treatment in all strains, indicating that SRE may have antimutagenic effects. Reverse mutation was not shown at all concentrations of SRE, regardless of application of the metabolic activation system. In the chromosomal aberration test, one of the SRE sample gave a suspicious positive result at 250 ${\mu}g/ml$ in the presence of S-9 mix. For the more adequate evaluation of the genotoxic potential of SRE samples, other in vivo genotoxicity study is needed.

• Korean Journal of Food Science and Technology
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• v.51 no.6
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• pp.517-523
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• 2019

In this study, we investigated antioxidant capacity of 20 strawberry extract using the DPPH and ABTS assay and HPLC-DAD validation method. The total polyphenolic and flavonoids contents of 20 strawberry extracts were 22.77-107.61 mg TAE/100 g FW and 17.58-44.12 mg QE/100 g FW. The Aiberry and Elie star showed the highest total polyphenol and flavonoid contents, respectively. The DPPH radical scavenging activity of what was 1540.6-1124.0 μmol TEAC/100 g FW and Derunoka showed the highest activity. The ABTS radical scavenging activity was 6352.3-4592.3 μmol TEAC/100 g FW and FA23 showed the highest activity. The HPLC-DAD method for the quantitation of ellagic acid results showed high linearity in various concentration ranges, and the limit of detection was 2.35 μg/mL. The limit of quantification was 7.12 μg/mL. Relative standard deviation values from intra-and inter-day precision were less than 5.31%. Recovery rate at 10, 50, and 100 μg/mL, respectively, were 100.0-101.0% with relative standard deviation (RSD) values less than 5.30%. These results provide viable information for the validation of antioxidant capacity in strawberry fruits.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.97-108
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• 1995

Nitrate concentration and ${\delta}^{15}N$ value in the groundwater in Miyakojima Island, Okinawa, were measured during 1992-1993. Water from the shallow and the deep wells at the ten separate sites were sampled. Mineral contents and natural nitrogen isotope abundance(${\delta}^{15}N$) were analyzed using a liquid chromatography and a mass spectrometry (Finnigan MAT 252). Except for waters which were directly influenced by sea water invasion, most of the groundwater showed small variations among their mineral contents and ${\delta}^{15}N$ values. The average nitrate nitrogen concentrations were $1.4{\sim}11.5mgL^{-1}$ and average ${\delta}^{15}N$ values were +4.3${\sim}$+9.7$%_o$. From the nitrate concentration and ${\delta}^{15}N$ value observed, the types of the groundwater could be categorized into four groups, such as high ${\delta}^{15}N$ and high nitrate, high ${\delta}^{15}N$ and medium nitrate, low ${\delta}^{15}N$ and medium nitrate, and low ${\delta}^{15}N$ and low nitrate, reflecting the main source of nitrate contamination, such as animal and domestic waste, animal waste and soil organic matter, soil organic matter and chemical fertilizer, and chemical fertilizer, respectively. It was discussed that the lowest ${\delta}^{15}N$ value was higher than the ${\delta}^{15}N$ value of the chemical fertilizers used in this island(-3.9${\sim}$-1.4$%_o$), then considerable amounts of nitrogen must be lost by ammonium evaporation or denitrification after fertilization.