• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.7-12
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• 2017

This experiment was conducted to analyze the effect of drainage reuse rate on the growth and fruiting of summer paprika in closed hydroponic cultivation. The experiment was carried out for 25 weeks from March to September 2015 with 0, 20, 30, 50% mixing ratio of waste nutrient solution using non - recycling hydroponic cultivation as a control. As a result, stem diameter of the test was different in the groups 1 and 2, but no difference showed as the group progressed more than 3 groups. L.A.I tended to decrease with increasing drainage mixing ratio. The number of nodes in the 50% reuse test group was 1.4 compared to the control group, but there was no significant difference. The number of harvested nodes was significantly different in the control group (11.1 nodes) and the 50% reuse test group (8.7 nodes), and the harvested nodes tended to decrease as the drainage was reused. The ratio of harvest was also the same as that of the harvesting node, and the control was the highest at 33.2% and the lowest at the 50% reuse test at 27.6%. Relative yields were reduced by 30%, 35% and 45% in the control group in the first group, and this tendency was also observed in the second and fourth groups. However, in the 3 and 5 groups, the production of 50% test group increased by 13% and 5%. The ratio of unmarketable fruit was increased 2%, 4%, 4%, and 7% in 0%, 20%, 30% and 50% reuse test, respectively. In conclusion, if the decrease in yield due to the decline in early growth is carefully managed, even if the imbalance of inorganic ions occurs after the mid-term growth, the growth of the crop will enter into a stable period and the re-use will not be worried about the growth and the yield decrease.

• Journal of Bio-Environment Control
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• v.24 no.4
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• pp.275-280
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• 2015

The objective of this study was to investigate the effect of drip irrigation level on soil salinity and growth of broccoli (Brassica oleracea L. var. italica) at the 'Saemangeum Reclaimed Tidal Land' from April to June, 2015. Drip irrigation was conducted at 1.5, 3.0 and $6.0mm{\cdot}day^{-1}$ level for reduction of resalinization in the plastic vinyl house using 10cm spacing drip irrigation tape. At harvesting stage, the average EC of surface soil was $10.9dS{\cdot}m^{-1}$ for $1.5mm{\cdot}day^{-1}$, $11.5dS{\cdot}m^{-1}$ for $3.0mm{\cdot}day^{-1}$ and $5.1dS{\cdot}m^{-1}$ for $6.0mm{\cdot}day^{-1}$ and was significantly reduced by 52~56% in $6.0mm{\cdot}day^{-1}$ treated plot compared to those in 1.5 and $3.0mm{\cdot}day^{-1}$ plots. The fresh bud weights of 1.5, 3.0 and $6.0mm{\cdot}day^{-1}$ treatment plots were 60.9, 129.1 and $371.3g{\cdot}plant^{-1}$, respectively. The estimated soil EC for 50% yield reduction was $7.6dS{\cdot}m^{-1}$ and the desalinization depth by drip irrigation was 30~40cm in soil profile. The total amount of drip irrigation water was estimated to be 422mm and the daily drip irrigation level was $6.0mm{\cdot}day^{-1}$ for the prevention of resalinization during the broccoli growing period at the 'Saemangeum Reclaimed Tidal Land'. Our results suggested that drip irrigation shows effectiveness on the lowering the soil salinity according to the drip irrigation quantity but it needs more research on this study because dynamics of salts in soil can vary with many factors such as soil physico-chemical properties and seasonal climate.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.592-598
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• 2012

Forest stand yield and its changes along with 10 thinning scenarios were estimated using a forest stand yield model for six major tree species in Korea, such as Pinus densiflora in Gangwon province, Pinus densiflora in other regions, Pinus koraiensis, Larix leptolepis, Quercus acutissima Carruth, Quercus mongolica. The 10 thinning scenarios were generated based on a number of constraints and assumptions. For instance, it was assumed that thinning is implemented between 15 years and 40 years with 5 year period and its duration should be at least 10 years. Also, the overall removal rate from the thinning treatments was assumed to be not greater than 60%. Under the 10 scenarios, the overall stand yield volumes from thinning and final harvesting were estimated for each species and site index. The results showed that highest yield volumes were obtained for Pinus densiflora in Gangwon province, Pinus koraiensis and Quercus mongolica when 30% of basal areas were thinned at 20 and 40 years, while highest yield volumes were obtained for Pinus densiflora in other regions and Larix leptolepis when 20% of basal areas were thinned at 20, 30 and 40 years. Those two scenarios gave the same amount of highest yield volume for Quercus acutissima Carruth. Also the results indicated that thinning treatment is effective to increase overall stand yield volume and its effects are larger with a higher site index. The largest thinning effects were found in Pinus densiflora in Gangwon province (28%) and Larix leptolepis (25%), while limited in Pinus koraiensis (12%). The forest stand yield model, used in this research, could be an effective tool for estimating the stand dynamics with various thinning treatments, but it could be improved in a further research that validates its applicability in the field.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.5
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• pp.97-104
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• 2017

Greenspace enlargement through proper landscape planting is essential to creating a low carbon society. This study analyzed changes in stem diameter growth rates(DGR), ratios of below ground/above ground biomass(B/A), and carbon sequestration by age of major landscape tree species. Landscape trees for study were 11 species and 112 individuals planted in middle region of Korea. The DGR and B/A were analyzed based on data measured through a direct harvesting method including root digging. The carbon sequestration by tree age was estimated applying the derived regression models. The annual DGR at breast height of trees over 30 years averaged 0.72 cm/yr for deciduous species and 0.83 cm/yr for evergreen species. The B/A of the trees over 30 years averaged 0.23 for evergreen species and 0.40 for deciduous species, about 1.7 times higher than evergreen species. The B/A by age in this study did not correspond to the existing result that it decreased as tree ages became older. Of the study tree species, cumulative carbon sequestration over 25 years was greatest with Zelkova serrata(198.3 kg), followed by Prunus yedoensis(121.7 kg), Pinus koraiensis(117.5 kg), and Pinus densiflora (77.4 kg) in that order. The cumulative carbon sequestration by Z. serrata offset about 5% of carbon emissions per capita from household electricity use for the same period. The growth rates and carbon sequestration for landscape trees were much greater than those for forest trees even for the same species. Based on these results, landscape planting and management strategies were explored to improve carbon sequestration, including tree species selection, planting density, and growth ground improvement. This study breaks new ground in discovering changes in growth and carbon sequestration by age of landscape trees and is expected to be useful in establishing urban greenspaces towards a low carbon society.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.257-263
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• 2016

Recently, an interest has developed in the use of whole green grains as functional food materials. The present study was conducted to provide the baseline data for the stable production of whole green grains in 20 cultivars of wheat by investigating the greenness of grain with maturation (from $20^{th}$ to $41^{st}$ day after heading, at an interval of 3 days). On the $20^{th}$ day after heading, the grains were dark green with a wrinkled long-oval shape. After the $35^{th}$ day of heading, the grains turned almost yellow with an oval shape. Their redness ('a' value of chromaticity) increased from the $20^{th}$ to $41^{st}$ days after heading, indicating a negative value up to the $32^{nd}$ day after heading. A significant decrease in their chlorophyll content was observed with maturation. The yield of whole green wheat grain (including greenish yellow grain) was the highest from the $32^{nd}$ to $35^{th}$ after heading. Therefore, we concluded that the optimal harvesting period for whole green wheat grain was from the $32^{nd}$ to $35^{th}$ day after heading. The heading time of various cultivars ranged from April 28 to May 5, the time of Jopummil cultivar grew the fastest among them, such as Gurumil, Alchanmil, but Dahongmil got the latest in heading time. The greenness of seven cultivars (Jeokjungmil, Keumkangmil, Jogyeongmil, Jopummil, Baekjungmil, Yeonbaekmil, and Milseongmil) was relatively higher than that of the others. The yield of greenish whole grain was relatively high in six cultivars (Alchanmil, Baekjungmil, Eunpamil, Yeonbaekmil, Dahongmil, and Urimil). Based on their greenness and yield, the Baekjungmil and Yeonbaekmil cultivars have been considered to be optimal for the production of whole green wheat grain.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.31-38
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• 1994

This study was carried out to investigate the possibility of potential injury to crops which were exposed to precipitation. The rainwater were collected from May to September in 1992 and analyzed its chemical composition. The amounts of chlorophyll and cations in plant were measured, and the morphological structure of epidermis was also investigated by SEM. The results are summarized as follows: 1. The pH of precipitation in Suwon was relatively high even with high level of $SO_4^{2-}$ and monthly pH at May, June, July, August, and September were 4.65, 5.47, 5.32, 5.44 and 4.80, respectively. 2. The amount of ions in rainwater was in the order of $NH_4^+$, $Ca^{2+}$, $Mg^{2+}$ and $H^+$ for cations, and $SO_4^{2-}$, $NO_3^-$ and $Cl^-$ for anions. 3. pH of rain in less than 5mm of precipitation was higher than that in greater than 5mm of precipitation. 4. The amount of chlorophyll was higher in the plant exposed to rain than that in plant intercepted rain during the early portion of growing season, but at the later period, the trend was shown to be reversed. 5. When the sesame plants were exposed to rain at harvesting stage, they contained less amount of CaO, MgO and $Na_2O$ than those with the interception of rain. 6. Scanning electron microphotographs revealed the shringkage in glandular trichomes in the epidermis of sesame leaves when they were exposed to rain.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.441-448
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• 2010

This study was carried out to investigate the effects of the seeding dates and growth periods on the growth characteristics, dry matter yield and feed value of corn for silage in paddy field. The experimental design was arranged in a randomized block design with three replications. Treatments consisted of five seeding dates, 1 May (T1), 8 May (T2), 15 May (T3), 22 May (T4) and 29 May (T5). And harvesting time homologized by August 24. Therefore, growing periods were 115 days (T1), 108 days (T2), 101 days (T3), 94 days (T4) and 87 days (T5), respectively. In maturities at harvest time, T1, T2, T3, T4 and T5 were full dent, early dent, late dough, dough and early dough stage, respectively. Plant height and numbers of root system were highest in T5 (p<0.01), but leaf length was higher in T4 than others (p<0.05). Dead leaf, tip filling degree and ear circle were higher in T1 than others (p<0.05, 0.01). Leaf width, ear height, leaf number, ear length, stem diameter, stem hardness and brix were not significantly different among the treatments. Dry matter yield and TDN yield were higher in the order of T1 > T2 > T3 > T4 > T5 (p<0.01). Crude protein, crude ash, NDF, ADF and crude fiber were significantly higher in T4 (p<0.05, 0.01). But crude fat was the highest in T1, T3 was the lowest as compared to other treatments (p<0.01). Total EAA(essential amino acids) were higher in order of T4 > T3 > T1 > T2 > T5, and total NEAA (nonessential amino acids) were higher in order of T1 > T4 > T2 > T3 > T5, and total amino acids were higher in order of T4 > T1 > T3 > T2 > T5. But no significant differences were found among the treatments. TUFA (total unsaturated fatty acid) and TSFA (total saturated fatty acid) were in order of T1 > T2 > T3 > T5 > T4 (p<0.01). Minerals were the highest in T4 (4,721.25 mg/kg), and T2 (2,970.80 mg/kg) was the lowest as compared to other treatments (p<0.05). Based on the above results, seeding dates could be recommended as early May, and harvest times is yellow ripe stage for qualitative and quantitative production of corn for silage in rice paddy field soil.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.493-497
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• 2000

An experiment was conducted to evaluate the possibility of using basic oxygen furnace (BOF) slag as soil conditioner in soybean upland field. In 1997, soybean (Glycine max L. cv. Eunha) crop was cultivated under different application rates of BOF slag at an experimental field of Chonnam Rural Development Administration in Nampyung, Najoo city. Five treatments, four application rates of BOF slag (0, 4, 8, $12Mg\;ha^{-1}$) and one application rate of lime ($2Mg\;ha^{-1}$) were tried with three replications. Plant height and shoot dry weight per plant were measured five times during the growth period. Chemical contents of soybean plant tissues and soil were also measured at the same sampling date. Yield were estimated by harvesting $6.6m^2$ per experimental unit and yield components were measured by sampling 10 plants per experimental unit at the harvest date. In upland soil, application of BOF slag rarely affected contents of total nitrogen, organic matter, available phosphate and potassium in soil. Soil pH, and contents of Ca and Fe in soil became higher as BOF slag rate increased. Enhancement of soil pH by application of BOF slag appeared to be closely related with increase in soil Ca content. Application rate of $2Mg\;ha^{-1}$ of lime showed almost the same effect in increase of soil Ca content as application rate of $4{\sim}8Mg\;ha^{-1}$ of BOF slag. Slag treatment hardly affected the contents of total nitrogen, $P_2O_5$, CaO, $K_2O$ and MgO in the shoot of soybean plants. Soybean plants under treatments of BOF salg showed better growth from the earlier growth stage compared with those of control treatment, and at the later growth stage, their growth was even superior to that of lime treatment. BOF slag rate of $8Mg\;ha^{-1}$ showed the highest soybean yield with $1,232kg\;ha^{-1}$. which was $330kg\;ha^{-1}$ or 37% higher than the yield of control with $902kg\;ha^{-1}$, As a result, BOF slag appeared to be useful material as a soil conditioner as well as nurient source for Ca and Fe in upland soybean fields, and its optimal rate for higher yield seemed to be around $8Mg\;ha^{-1}$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.1-10
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• 1982

Degree of grain shattering which is of varietal character is an important determinant for the magnitude of field loss of grains during harvest and threshing. Seven Indica \times Japonica progeny varieties and four Japonica varieties were subjected to measurements of tensile strength of grains, degree of grain shattering when panicles were dropped at 1.5m above concrete floor, and moisture content of grains (wet basis) during a period 35 to 63 days after heading. In addition, two varieties were tested for the relation of tensile strength of grains to the magnitude of field loss of grains in actual binder harvest. The 11 varieties differed conspicuously in tensile strength of grains and the degree of grain shattering: the weakest average tensile strength of grains of a variety was about 90g and the strongest about 250g with varying standard deviation of 30 to 60g. Three Indica \times Japonica varieties and one Japonica variety shattered I to 30% of the grains under the falling test. The threshold tensile strength of grains allowing grain shattering was estimated to be 180g on average for a sampling unit of 10 panicles, but only the grains having tensile strength weaker than 98g within the samples shattered. A decrease in average tensile strength by 10g below the threshold value corresponded to an increase of 3 to 5% in grain shattering. Most varieties did not change appreciably the tensile strength of grains and degree of grain shattering with delay in time of harvest and showed a negative correlation between the tensile strength and the moisture content of grains. The average tensile strength of grains was negatively correlated linearly with field loss in binder harvest. The average tensile strength for zero field loss in binder harvest was estimated to be 174g and a decrease in the average tensile strength by 10g corresponded to an increase of 40kg per hectare in field loss of grains. Instead of the average tensile strength of grains, the percentage of grains having tensile strength weaker than 100g is recommended as a criterion for the estimation of field loss of grains during harvesting operations as well as a basis of variety classification for grain shattering, since the standard deviation of tensile strength of grains varies much with variety and time of harvest, and individual grains having tensile strength stronger than 98 did not shatter practically.

• Journal of Food Hygiene and Safety
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• v.33 no.5
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• pp.404-411
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• 2018

To evaluate bacteriological and toxicological safety hygienic indicator bacterium and paralytic and diarrhetic shellfish toxins in the shellfish produced in Hansan Geojeman 2013-2017 were investigated. Fecal coliforms were < 18~330 MPN/100 g in 404 oyster samples. But all samples tested, did not exceed 230 E. coli MPN/100 g. Geometric mean of E. coli for oyster samples collected during major shellfish production period was 24.3 MPN/100 g, considerde stable results. Bacteriological quality of oysters collected from Hansan Geojeman meets the standard value based on shellfish hygiene of the Food Sanitation Act of Korea and also meets Grade A, according to classification of shellfish harvesting areas of the European Union. For toxicological evaluation of Hansan Geojeman, 532 oyster samples and 268 mussel samples as an indicator, were analyzed. Paralytic shellfish toxins were detected in the range of 0.42~2.29 mg/kg in eight mussel samples, and exceeded criteria in three samples from early to late April 2013. Diarrhetic shellfish toxin was detected in three of 120 samples, but it was revealed to be under regulation value (0.16 mg Okadaic Acid equ./kg). As a result of toxicological evaluation, paralytic and diarrhetic shellfish toxins were not detected in oyster samples, but it was found that mussel as an indicator species, exceeded the threshold value of paralytic shellfish toxin. Accordingly, sanitary surveys were continuously requested for food safety management of shellfish.