• Horticultural Science & Technology
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• v.34 no.4
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• pp.564-577
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• 2016

Salinity stress limits plant cultivation in many areas worldwide; however, persimmon (Diospyros spp.) has high tolerance to salt. Five accessions of Diospyros [three of Diospyros lotus (accession numbers 824, 846, and 847); one of Diospyros kaki var. sylvestris (869); and one of Diospyros virginiana (844)] were chosen for analysis of salinity stress. We compared the effects of salt stress on plant growth, relative water content (RWC), malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide content ($H_2O_2$), and antioxidative enzyme activities (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD; and ascorbate peroxidase, APX) in leaves of healthy potted seedlings from each of the five accessions after salt treatment for 25 days. Salt stress affected the growth of plants in all five accessions, with all three D. lotus accessions showing the most severe effect. Salt stress increased membrane lipid peroxidation in all accessions, but a stronger increase was observed in the three D. lotus accessions. Moreover, accumulation of $H_2O_2$ was faster in salt-sensitive D. lotus compared to salt-tolerant D. virginiana 844. The activities of all antioxidant enzymes increased in D. virginiana 844 and in D. kaki var. sylvestris 869; the activities of SOD, CAT, and APX were at similar levels in D. virginiana 844 and D. kaki var. sylvestris 869, but POD activity was stimulated to a greater extent in D. virginiana 844. The activities of all antioxidant enzymes (except POD) decreased in D. lotus 824 and increased (except for SOD) in D.lotus 846. The activities of SOD and APX decreased in D. lotus 847, whereas POD and CAT activities both increased. Relative water content decreased significantly in D. lotus. No significant changes in lipid peroxidation or relevant antioxidant parameters were detected in any of the accessions in controls treated with 0.0% NaCl. D. virginiana 844 had higher antioxidant capacity in response to salinity compared to other persimmon rootstocks. These results indicate that changes of these key physiological variables are related to salinity resistance in different accessions of persimmon.

• Journal of The Korean Association For Science Education
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• v.33 no.2
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• pp.511-521
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• 2013

This study aims to investigate the effects of science writing activities on the students' science-related attitude, motivation for learning science, and academic achievement. One hundred and twenty seven second graders of a middle school located in Gyeonggi province participated in this study. The experimental group performed science writing activities, while the comparative group performed problem solving activities at the end of the regular science lessons over 30 class hours. For the students' science-related attitude and motivation for learning science, TOSRA, PALS, and MSLQ were used with some modification and supplementation. For the students' academic achievement, scores on science examinations were used. The results of this study are as follows: First, the test of the science-related attitude showed that science writing activities have positive effects on the cultivation of sciencerelated attitude, as for the sub-factors, 'attitude towards scientific inquiry,' 'pleasure of science lessons,' and 'active attitude towards science'(p<.05). Second, the test of motivation for learning science showed that the science writing activities had positive effect on the improvement in students' motivation, as for the sub-factors, 'difference in values on task' and 'self-efficacy'(p<.05). Third, science writing activities are effective on improvement in the students' academic achievement(p<.05), especially on the high-level achievement group.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.57-66
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• 2013

Although the quantity of dredged soils has increased owing to recent new harbor construction, sea course management, polluted sediment dredging, and four-river project, the reuse or recycling of those dredged soils has not done properly in Korea. To develop measures to utilize them in various ways for reuse or recycling, the biophysicochemical properties of dredged soils and sediment were assessed in this study. Samples were classified according to their sources-river and sea-by location, and as dredged soil and sediment depending on storage time. The results showed that dredged materials from the sea have high clay content and can be used for making bricks, tiles, and lightweight backfill materials, while dredged materials from the river have high sand content and can be used in sand aggregates. Separation procedures, depending on the intended application, should be carried out because all dredged materials are poorly sorted. All dredged soils and sediments have high salinity, and hence, salts should be removed before use for cultivation. Since dredged materials from the sea have adequate concentrations of nutrients, except phosphate, they can be used for creating and restoring coastal habitats without carrying out any additional removal processes. The high overall microbial activities in dredged materials from the river suggested that active degradation of organic matter, circulation of nutrients, and provision of nutrients may occur if these dredged materials are used for cultivation purpose.

• The Korean Journal of Food And Nutrition
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• v.22 no.4
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• pp.644-649
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• 2009

This study was conducted to determine the influence of cultural conditions such as temperature, time, water content, koji-thickness and agitation on the production of saccharifying amylase by Rhizopus sp. ZB9 isolated from Korean Nuruk during the preparation of rice koji, which is used in brewing Korean rice wines, Takju and Yakju. Rice kojies were made under different cultural conditions, and the saccharifying activities of each koji were tested. The temperature range suitable for the production of saccharifying amylase was $28{\sim}36^{\circ}C$. Based on the saccharifying activity and color, 60 hours of cultivation at $28^{\circ}C$ was believed to produce the optimum results. The water contents of steamed rice suitable for the production of saccharifying amylase were 35~40%. An increase in koji-thickness induced no adverse effects on the production of saccharifying amylase, but agitation-work during cultivation had a harmful effect.

• Journal of Microbiology and Biotechnology
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• v.11 no.1
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• pp.40-49
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• 2001

The present work presents a novel approach for the dynamic quantification of respiration rates on a small scale by using lysine-producing Corynebacterium glutamicum ATCC 21253. Cells sampeld from batch cultures at different times were incubated ina 12-ml scale bioreactor equipped with a membrane mass spectrometer. Under dynamic conditions, gas exchange across the gas-liquid phase, specific respiration rates, and RQ values were precisely measured. For this purpose, suitable mass balances were formulated. The transport coefficients for $O_2$ and $CO_2$, crucial for calculating the respiration activity, were determined as $k_La_{O2}=9.18h^{-1}$ and $k_La_{CO2}=5.10h^{-1}$ at 400 rpm. The application of the proposed method to batch cultures of C. glutamicum ATCC 21253 revealed the maximum specific respiration rates of $q_{O2}=8.4\;mmol\;g^{-1}h^{-1}\;and\;q_{CO2}=8.7\;mmol\;g^{-1}h^{-1}$ in the middle of the exponential growth phase after 5 h of cultivation. When the cells changed from growth to lysine production due to the depletion of the essential amino acids theonine, methionine, and leucine, $q_{O2}\;and\;q_{CO2}$ decreased significantly and RQ increased. The respiration data exhibited an excellent agreement with previous cultivations of the strain [13]. This confirms the potential of the developed approach to realistically reflect the metabolic activities of cells at their point of sampling. The short-term influence of added threonine, methionine, and leucine was highest during the shift from growth to lysine production, where $q_{O2}\;and\;q_{CO2}$ increased 50% within one minute after the pulse addition of these compounds. Non-growing, yet lysine-producing cells taken from the end of the batch cultivation revealed no metabolic stimulation with the addition of threonine, methionine, and leucine.

• Korean Journal of Organic Agriculture
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• v.23 no.2
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• pp.291-299
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• 2015

This study aimed to investigate the effect of inoculation time of phosphate- solubilizing Kluyvera sp. CL2 on fruit quality in cultivation of Campbell early' grape. When phosphate-solubilizing strain was treated at the stone-hardening stage, soil phosphorous increased, exchangeable cations such as K, Ca and Mg also increased. Soil pH was not changed severely due to the soil buffer capacity. Water soluble phosphate concentrations did not decrease heavily up to 20 days after inoculation. When this strain was treated at the berry-softening stage, soil phosphate solubilization ratio was high, cluster weight and sugar content also increased. Both anthocyanin contents and Hunter's values were seen to be significant when inoculation times were stone-hardening stage and berry-softening stage, in particular, increase of Hunter's value a resulted in the improvement of coloration. From these results, we could find that the inoculation of phosphate-solubilizing Kluyvera sp. CL2 at berry-softening stage was the most effective in improvement of fruit productivity and quality in cultivation of'Campbell early' grape.

• Korean Journal of Medicinal Crop Science
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• v.25 no.2
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• pp.95-101
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• 2017

Background: Callus cultivation has the advantage of producing a large amount of tissue of a plant in a laboratory regardless of the environment, for extracting an active substance. In the present study, callus formation was induced in the leaves of the succulent plant Adenium obesum (Forssk.) Roem & Schult. After callus cultivation, anti-inflammatory activity tests were conducted, because leaves and stems of A. obesum have been reported to possess biological activity. Methods and Results: In order to induce callus formation, various concentrations of plant growth factors, such as kinetin, naphtha-leneacetic acid (NAA), 6-benzyladenine (BA), and indole-3-acetic acid (IAA) were added to MS solid medium. The maximum callus proliferation was induced by mixed medium consisting of NAA ($2mg/{\ell}$) and BA ($1mg/{\ell}$). In addition, an elicitor was added to the medium under optimal conditions for initiating suspension culture. After suspension culturing, the activities of the callus extracts were compared and analyzed. The cytotoxicity and anti-inflammatory activity tests revealed that the anti-inflammatory activity of the callus extract and the content of phenolic compounds were elevated after treatment of the callus culture with the elicitior. Conclusions: A. obesum callus might be considered as potential source of biologically active anti-inflammatory material.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.3
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• pp.109-121
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• 2020

Converting the agricultural land-use of rice field to upland has been increasingly conducted as farmers encourages themselves to grow higher value-added crops on rice fields under the policy support. Comparing to rice field, Upland shows different characteristic of discharge due to the slope, scale, and shape of field and characteristics of rainfall event. In this study, we designed the experiment fields reflecting flat-upland characteristics with different land scale, and tried to collect the discharge and load data. Soybeans and corn were selected as target crops considering the possibility of large-scale cultivation and crop demand. The cultivation was conducted during the growth period in 2019 with 3 different field scales. Hence, we have collected the discharge data from 17 rainfall events and the load data for 8 rainfall events. As a result, the magnitude of rainfall events and the discharge duration were found to have a strong positive correlation and field discharge occurred during the period by 55% to 83% of rainfall duration. Besides we found other relationships and characteristics of rainfall event, discharge, and pollutant load and also pointed out that continuous monitoring and more data are required to derive statistically significant results. Compared with slope-field monitoring data obtained from the precedent research, the runoff ratio of the flat-fields was significantly lower than slope-fields. Overall the discharge in the slop and flat-fields shows appreciably different characteristics so that the related researches need to be further conducted to reasonably assess environmental impact of agricultural activities at flat-field.

• Journal of Korean Elementary Science Education
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• v.23 no.4
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• pp.305-317
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• 2004

The learning materials in elementary school science textbooks should include all kinds of materials being used by both teachers and students in the science teaching. The major purpose of this research is to analysis textbooks and teacher's guidebooks prepared for the science teaching of 3-6 grade students. To clarify this research, we listed whole of the learning materials of science teaching for each grade and counted numbers being used for whole of the lessons of science. And according to the characteristics and the methods of its preparation of materials, the types of learning materials can be divided into 10 categories such as teaching equipments for science, test materials, consumables, audio-visual aids, teaching equipments in general, collecting' recycling materials, field studies' collected data, breeding' cultivation materials, manufacture materials, and etc. At the result of this research, the 7th national science curriculum needs total 844 items of learning materials for science education. They could be separated into ten types of categories such as 159 items of teaching equipments for science, 65 items of test materials, 116 items of consumables, 198 items of audio-visual aids, 64 items teaching equipments in general, 31 items of collecting' recycling materials, 38 items of field studies (collecting) materials, 17 items of breeding-cultivation materials, 58 items of manufacturing materials, 105 items of other materials. And we found out that there were 332 items of materials for the 3rd grade, 303 items for the 4th grade, 324 items for the 5th grade, and 254 items for the 6th grade. The result of this research could be useful for classroom activities for science teaching.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1726-1736
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• 2013

Biosynthesis of indole-3-acetic acid (IAA) via the indole-3-pyruvic acid pathway involves three kinds of enzymes; aminotransferase encoded by aspC, indole-3-pyruvic acid decarboxylase encoded by ipdC, and indole-3-acetic acid dehydrogenase encoded by iad1. The ipdC from Enterobacter cloacae ATCC 13047, aspC from Escherichia coli, and iad1 from Ustilago maydis were cloned and expressed under the control of the tac and sod promoters in E. coli. According to SDS-PAGE and enzyme activity, IpdC and Iad1 showed good expression under the control of $P_{tac}$, whereas AspC was efficiently expressed by $P_{sod}$ originating from Corynebacterium glutamicum. The activities of IpdC, AspC, and Iad1 from the crude extracts of recombinant E. coli Top 10 were 215.6, 5.7, and 272.1 nmol/min/mg-protein, respectively. The recombinant E. coli $DH5{\alpha}$ expressing IpdC, AspC, and Iad1 produced about 1.1 g/l of IAA and 0.13 g/l of tryptophol (TOL) after 48 h of cultivation in LB medium with 2 g/l tryptophan. To improve IAA production, a tnaA gene mediating indole formation from tryptophan was deleted. As a result, E. coli IAA68 with expression of the three genes produced 1.8 g/l of IAA, which is a 1.6-fold increase compared with wild-type $DH5{\alpha}$ harboring the same plasmids. Moreover, the complete conversion of tryptophan to IAA was achieved by E. coli IAA68. Finally, E. coli IAA68 produced 3.0 g/l of IAA after 24 h cultivation in LB medium supplemented with 4 g/l of tryptophan.