• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.146-150
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• 2011

A large amount of nitrogenous compounds are found in burley tobacco and are responsible for peculiar aroma during smoking. Excess in nitrogen or its compounds such as total nitrogen and proteins in burley tobacco gives a strong pungency and make its taste bad. The present study has focused on improving quality of Burley tobacco by regulating topping and harvesting time of leaf to reduce nitrogen compounds in Burley tobacco. In addition, the early-stage of flower topping had lower level of nitrogenous compound, such as total nitrogen and protein nitrogen, and total tobacco-specific nitrosamine (TSNA) contents compared to the button-stage and full flower-stage topping. Also, the contents of nicotine got significantly decreased while the ether extract was increased as the period of topping got delayed. Regarding the brightness among the colors of cured leaves, the color at the full flower-stage topping was the brightest, and there was no particular difference in red and yellow colors. The harvesting amount was decreased as the period of topping got delayed and there was no significant difference between the topping treatments in terms of the exterior quality. As the harvesting time delayed, the total nitrogen, protein nitrogen, nitrate nitrogen, and ammonium nitrogen were decreased while the nicotine contents got increased. Also, the total TSNA contents were decreased as the harvesting time delayed. However, ether extract was increased. Among the colors of cured leaves, the brightness and degree of yellow color were significantly increased as the harvesting time delayed, and there was no particular difference in the degree of red color. The harvesting amount was decreased along with the delayed harvesting time; however, the harvest of the matured and mellow leaves was higher in terms of price, compared to that of the immature leaves. For the reduction of nitrogenous compound and TSNA contents in Burley tobacco, the topping was examined to be more effective in terms of improvement in chemical contents and quality regardless of the decreased harvesting amount.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.1
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• pp.45-54
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• 2009

This experiment was conducted to clarify the effects of source and sink related characteristics on grain weight increase and grain nitrogen accumulation in rice. Source was modified by leaf removing treatment with no sink modification in 2002 and sink and source were modified at the same time by different sowing dates, N fertilization rates, row spacings, and thinning treatments at heading in 2007. Grain weight (GW) and grain assimilates produced by photosynthesis during grain-filling ($GW_P$) increased with the increase of source, while the grain assimilates retranslocated from leaf and stem ($GW_T$) decreased. Among the source-related characters, shoot dry weight were most closely related with GW. GW was dependant on $GW_P$ rather than on $GW_T$. Grain nitrogen content (GN) and grain nitrogen absorbed from soil during grain-filling ($GN_S$) increased with the increase of source, while the grain nitrogen retranslocated from leaf and stem ($GN_T$) decreased. Shoot nitrogen content among the source-related characters was related most closely with GN. The contribution of $GN_T$ to GN was relatively large although GN depended more largely on $GN_S$ than $GN_T$. In addition, GN was supplied firstly from $GN_S$ or from $GN_S$ and $GN_T$ at the same time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.251-255
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• 2008

This study was carried out in 2002 to determine the usefulness of Jeju scoria for a component of a growth medium and optimum planting density of 'Dejima' seed potatoes (Solanum tuberosum L.) grown in a wick hydroponic system. The minitubers ($7.0{\pm}0.2\;g$) produced in an aeroponics system were planted at five planting densities (3 to 15 tubers/box; 19 to $95\;tubers/m^2$) in polystyrene boxes (51 cm long $\times$ 31 cm wide $\times$ 20 cm high) containing two media (perlite + peatmoss and Jeju scoria + peatmoss 1:2, v/v mixtures). There were no significant interactions between medium and planting density for the growth and tuber yield traits. Shoot growth and the number of tubers per plant were not significantly affected by the media. However, tuber yield was higher in the perlite + peatmoss mixture than in the Jeju scoria + peatmoss mixture. The percentage of underdeveloped plants ranged from 8.3 to 14.7% at four lower planting densities (3 to 12 tubers/ box), and was 25.8% at the highest planting density (15 tubers/box). As planting density was increased from 3 to 15 tubers per box, seed potato (${\geq}5\;g$ tuber) number increased from 101 to 269 and yield from 6.3 to $11.6\;kg/m^2$. These results indicate that the perlite + peatmoss mixture might be more suitable for seed potato production in the wick hydroponic system, and considering the percentage of underdeveloped plants and tuber yield, optimum planting density would be 56 to $76\;tubers/m^2$ in the system depending on availability of seed potatoes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.164-173
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• 2018

Elevated atmospheric carbon dioxide concentration ($CO_2$) is a major component of climate change, and this increase can be expected to continue into the crop and food security in the future. In this study, Soil-Plant-Atmosphere-Research (SPAR) chambers were used to examine the effect of elevated $CO_2$, temperature, and drought on the canopy architecture and concentration of macronutrients in potatoes (Solanum tuberosum L.). Drought stress treatments were imposed on potato plants 40 days after emergence. Under AT+2.8C700 (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$), at maximum leaf area, elevated $CO_2$, and no drought stress, a significant increase was observed in both the aboveground biomass and tuber, and for the developmental stage. Even though $CO_2$ and temperature had increased, AT+2.8C700DS (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$ under drought stress) under drought stress showed that the leaf area index (LAI) and dry weight were reduced by drought stress. At maturity, potatoes grown under $CO_2$ enrichment and no drought stress exhibited significantly lower concentrations of N and P in their leaves, and of N, P, and K in tubers under AT+2.8C700. In contrast, elevated $CO_2$ and drought stress tended to increase the tuber Mg concentration under AT+2.8C700DS. Plants grown in AT+2.8C700 had lower protein contents than plants grown under ATC450 (30-year average temperature at $400{\mu}mol\;mol^{-1}$ of $CO_2$). However, plants grown under AT+2.8C700 showed higher tuber bulking than those grown under AT+2.8C700DS. These findings suggest that the increase in $CO_2$ concentrations and drought events in the future are likely to decrease the macronutrients and protein concentrations in potatoes, which are important for the human diet.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.30-39
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• 2020

A new silicate coating technology was developed which reduces the impact of dust and loosening during seeding compared to existing silicate-coatings (Seed/Si/Zeolite), and therefore can lower the production costs of rice cultivation. In this method, 100 g of rice seed is coated with 18 mL of liquid silicic acid and then dressed with a mixture containing 80 g of dolomite and 5 g of iron. To determine the most effective method of application and ensure that seedlings developed healthily, a series of experiments were carried out. Infected seeds scattered in seedling boxes and pots (soil and hydroponic) were coated dry, without disinfection. In comparison to the seed which were not treated with the silicate-coating, the new seed (A) were 1.84 times heavier in weight, and were also improved in terms of coating strength and coating color. Compared to the seedlings grown from the non-coated seed, those grown from the new silicate-coated seed were of significantly higher quality (weight/length) and had erect, dark greenish leaves, which are ideal plant characteristics. This was most likely due to increased silicate uptake. The symptoms of bakanae disease in the non-coated seed peaked after 38 days to 54.2%, whereas the control value was 68.8% in the new silicate-coated seed (A). In the infected seedlings grown from the new silicate-coated rice seed, subnormal macro-conidia, namely, a sickle shape spore without a septum; a straight oblong shape spore without a septum and with a thick cell wall; and inter-septal necrosis of a normal spore were detected. It is believed that the strong alkalinity of silicic acid have acted as unfavorable conditions for pathogenicity. In seedlings grown from the new silicate coated rice seed under hydroponic conditions without nutrients, normal root activity and growth was maintained without leaf senescence. Therefore, it was possible to reduce the rate of fertilization. In the future, a new silicate-coated rice seed was required for the study of minimal nutrition for anti-aging of seedlings.

• Journal of Animal Environmental Science
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• v.15 no.1
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• pp.51-58
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• 2009

The compost leachate was dark-colored solution that leaches out of the bottom of the compost pile. The compost leachate was rich in nutrients and can potentially used in plant culture. In the organic production, commercial liquid fertilizer was used to insure the availability of nutrients during the formation of the yield. The cost of supplemental liquid fertilizer could be reduced by developing a fertilizer based on animal fertilizer. This experiment was conducted to investigate the effect of different combination of compost leachate and conventional inorganic solution in hydroponic culture for lettuce growth. Six different treatments were applied. The compost leachate(CL) and nutrient solution(NS) were mixed by six different mixing ratios of 0:100, 20:80, 40:60, 60:40%, 80:20 and 100%:0% based on nitrogen content. The chemical nutrient solution was the solution of National Horticulture Research Station for the growth of leaf lettuce. The concentration of nutrient solution was adjusted 1.5 mS/cm in EC. The compost leachate was low in phosphorus(P), calcium(Ca), magnesium(Mg), but rich in potassium(K). The plant height of lettuce treated with CL 20+NS 80% was similar with 100% NS of control plot. Plant height was highest in the plot of CL 20+NS 80%. The treatment of 100% compost leachate was lowest in the growth characteristics of leaf lettuce. Number of leaf was very low in 100% compost leachate compared with plot of chemical nutrient solution. In the beginning of growth stage, SPAD value was reduced in plot treated with CL100%, but CL20+NS80% plot was higher compared to 100% compost leachate. SPAD value of leaf lettuce leaves was decreased as the amount of CL was increased. The dry weight of lettuce were 107.4, 104.2g in plot of NS 100% and CL 20%+NS80%, respectively. The leaf number and plant weight were decreased at high application plots of compost leachate. The leaf lettuce showed lowest in the plot treated with 100% compost leachate, and the growth of lettuce severely decreased after application of 100% CL treatment. The results showed that compost leachate can be use as liquid fertilizer for the organic hydroponic production. The mixture solution of 20% of compost leachate and 80% of nutrient solution could be used as a nutrition solution in hydroponic culture of leaf lettuce. Our studies have shown that is possible to produce using compost leachate, although growth is slower than when using a conventional inorganic hydroponic solution.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.87-93
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• 2013

'Okhan' (Avena sativa L.), an oat cultivar for winter use, was developed by the breeding team at the Department of Rice and Winter Cereal Crop, NICS, RDA in 2011. It was derived from an original cross between 'Early80', exhibiting early heading, and 'Maine PI-590' (CI 7518), exhibiting large-size grain, in 1995. Subsequent generations as well as cross-bred cultivars were handled in bulk, and pedigree selection programs took place at Suwon and Yeoncheon, respectively. A promising line, 'SO95027-B-45-16-10-6-2-Y7-10', was selected in 2004, and was designated 'Gwiri74' after being selected from a yield trial for three years from 2005 to 2008. The breeding line 'Gwiri74' was subsequently evaluated for earliness of heading and forage yield in four different locations, Yesan, Iksan, Kimjae, and Jeju, from 2009 to 2011, and was finally named as 'Okhan'. Over 3 years, the heading date of 'Okhan' was about 6 days earlier than that of the check cultivar 'Samhan', and their average forage dry matter yield harvested at the milk-ripe stage was 15.0 ton $ha^{-1}$, compared with 14.1 ton $ha^{-1}$ of check cultivar. Cultivar 'Okhan' was lower than the check cultivar 'Samhan' in terms of the protein content (9.2% and 9.9%, respectively) and total digestible nutrients (58.5%, and 59.3%, respectively), while the TDN yield per ha was more than the check (8.70 and 8.36 kg, respectively). Fall sowing cropping of 'Okhan' is recommended only in areas where average daily minimum mean temperatures in January are higher than $-7^{\circ}C$, and it should not be cultivated in mountain areas, where frost damage is likely to occur.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.81-86
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• 2013

'Mogwoo', a new high yield and whole crop silage rice (Oryza sativa L.) cultivar, was developed by the rice breeding team of the National Institute of Crop Science, RDA, Suwon, Korea, from 1999 to 2009, and was released in 2010. It was derived in 1999 from a cross between Dasanbyeo, having a high yield, and Suweon431/IR71190-45-2-1. A promising line, SR25848-C99-1-2-1, selected by the pedigree breeding method, was designated the name of 'Suweon 519' in 2007. This cultivar has about 155 days of growth period from seeding to heading, and is tolerance to lodging, with erect pubescent leaves as well as a long and thick culm. This cultivar has the same number of tillers per hill and higher spikelet numbers per panicle compared to Nokyang. 'Mogwoo' has longer leaves compared with other Tongil-type varieties. This new variety is resistant to grain shattering, leaf blast, bacterial leaf blight, and small brown planthopper. The biomass yield of 'Mogwoo' was 1,956 kg/10a in a regional test over three years. The result shows that 'Mogwoo' is adaptable to central and south-east plain areas of Korea.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.1
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• pp.57-65
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• 2020

This study was conducted to investigate the effect of sowing and harvesting dates on agronomic characteristics and feed values of rye and triticale at Sanchoeng, South Korea. The experimental design consisted of the different sowing and harvesting dates as follows; rye (Secale cereale L., cv. Gogu) of sowing (October 15, 25, and November 5) in 2015 and harvesting (April 20, May 1 and May 11) in 2016, and triticale (X Triticosecale, cv. Joseong) of sowing (October 15, 25, and November 5) in 2015 and harvesting (May 18, 28, and June 7) in 2016. In rye, fresh and dry matter (DM) yields increased (p<0.05) with the delayed-harvesting date. Crude protein (CP) content and relative feed value (RFV) decreased (p<0.05) with the delayed-harvesting date, but neutral detergent fiber (NDF) content increased (p<0.05). In triticale, fresh and dry matter (DM) yields increased (p<0.05) with the delayed-harvesting date. The CP content decreased (p<0.05) with the delayed-harvesting date, but NDF content and RFV increased (p<0.05). This study concluded that rye sown in the middle of October then harvested in early May, and the triticale sown at the end of October then harvested at the end May are recommended to increase dry matter yield and feed value.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.