• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.67-71
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• 2019

All countries, including Korea, are currently experiencing the effect of rapid climate change. As a result, the cultivation area of many crops including wheat is changing, or productivity is falling sharply. If enough nitrogen is present in the soil, the increase in atmospheric carbon dioxide due to the greenhouse effect can lead to increased photosynthesis of plants, resulting in increased productivity. By contrast, a low proportion of nitrogen in soil does not increase production, often leading to the use of nitrogen fertilizers to increase crop productivity: this causes serious environmental pollution due to the leakage of nitrogen fertilizers used by crops. Increasing the understanding of the molecular level of the plant nitrogen use efficiency mechanism may contribute to increased productivity of crops and reduced of environmental pollution by nitrogen. In Korea, cultivars have developed 35 kinds of wheat, such as 'keumgang' and 'Chokyeong', which can be used for specific purposes such as baking or noodles. In this study we investigate 'keumgang' and 'Chokyeong' in order to elucidate the mechanism of nitrogen use ability of wheat and contribute to the reduction of environmental pollution by providing guidelines for the proper use of nitrogenous fertilizer.

• Journal of Ginseng Research
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• v.9 no.1
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• pp.36-41
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• 1985

The study was conducted to investigate the changes of soil physico-chemical properties between soils of preplanting fields and 2 years old ginseng fields, and compare the missing plant rate among the 2 years 016 ginseng fields. 1, The missing plant rate of 2 years old ginseng was high in sand loam while low in clay loam soil texture, soil porosity and NO3-N were remarkably increased in 2 years old ginseng field than preplanting soil, as the clay content was increased, soil porosity seemed to be increased but exchangeable nitrogen decreased. 2. The preplanting soil management methods did not significantly influenced on the missing plant rate and soil porosity in 2 years old ginseng fields, However NO3-N content and Fusarium density seemed to be decreased as the plow frequency was increased, exchangeable nitrogen content, whereas, seemed to be increased with more organic matter. 3. Differences of clay content (below 15% and above 20% of clay content) was significantly influenced on soil porosity, bulk density, total nitrogen, organic matter and P2O5 content. 4, Missing rate showed negative correlation with clay, soil moisture, and organic matter content but positive corelation with NO3-N in 2 years old ginseng fields.

• Journal of Embryo Transfer
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• v.14 no.2
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• pp.83-88
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• 1999

This study was undertaken with three objectives : to determine the optimal time of blood collection for plasma urea nitrogen(PUN) analysis, to examine the frequency distribution of PUN levels in recipient herd and to relate concentration of PUN to conception rate in Hanwoo recipients. The relationship between PUN level and time postfeeding was examined for 5 individual cows. Mean concentration of PUN rose for 4hrs postfeeding and decreased to PUN level before feeding at 10hrs postfeeding. And then, the blood for PUN analysis was collected at the time before feeding in next experiments. The ratio of cows with PUN concentration of < 12, 12∼18 and 18mg/dl were 50.6, 39.9 and 9.5% in 163 recipients, individually. The pregnancy rate of cows with PUN concentration 12∼16 mg/dl (63.3%) was higher than that of cows with PUN concnetration < 12 mg/dl (46.7%) or > 16mg/dl (42.9%). There results suggest that the PUN test may be beneficial for management of recipient herd in effects to maintain or improve reproductive efficiency.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.771-775
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• 2005

The purpose of this research was to investigate applicative possibility of field. Pilot-scale experiments were conducted, at outdoor temperature, HRT l0hour, IR(Internal Recycle) $150\%$ and used $2.8m^3$ Reactor. External carbon source was varied 80 to 120 mg/L. When External carbon source and Alkalinity were injected to the B3 pilot plant, the removal efficiencies of COD and BOD were not decreased. Nitrification rate were 5.95, 5.40, 4.08 $mgNH_4^+-N/gSS/d$ during operation periods and denitrification rate was $3.l2mgNO_3^--N/gSS/d.$ When we surveyed the relationship between loading rate of nitrogen and nitrogen removal quantity, this data was 0.949, B3 process will be possible application process of field.

• Journal of Environmental Science International
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• v.28 no.7
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• pp.629-637
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• 2019

The purpose of this study was to evaluate the effect of high-salinity wastewater on the microbial activity of Aerobic Granule Sludge (AGS). Laboratory-scale experiments were performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen removal efficiency, sludge precipitability, and microbial activity were evaluated under various salinity injection. The COD removal efficiency was found to decrease gradually to 3.0% salinity injection, and it tended to recover slightly from 4.0%. The specific nitrification rate was 0.043 - 0.139 mg $NH_4{^+}-N/mg$ $MLVSS{\cdot}day$. The specific denitrification rate was 0.069 - 0.108 mg $NO_3{^-}-N/mg$ $MLVSS{\cdot}day$. The sludge volume index ($SVI_{30}$) ultimately decreased to 46 mL/g. The specific oxygen uptake rate decreased from an initial value 120.3 to a final value 70.7 mg $O_2/g$ $MLVSS{\cdot}hr$. Therefore, salinity injection affects the activity of AGS, causing degradation of the COD and nitrogen removal efficiency. It can be used as an indicator to objectively determine the effect of salinity on microbial activity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.66-70
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• 1998

Four introduced forage rape (Brassica napus) cultivars, 'Akela', 'Ramon', 'Sparta', and 'Velox' and a leading rapeseed cultivar, 'Hallayuchae' were grown at nitrogen (N) rates of 0, 100, 250, 300, 350, and 400 kg/ha to (i) select forage rape cultivars adapted best to Cheju area, and (ii) determine the optimum N rate for the best cultivars. Days from seeding to flowering across the cultivars increased 190 to 195 days as N rate increased from 0 to 400 kg/ha. Average days to flowering of six cultivars ranged from 182 to 198 days. Plant height increased as N rate increased up to 300 kg/ha and then decreased with a further increase in N rate and ranged from 159 to 174 cm among the cultivars. The optimum N rate for the greatest dry matter yield of five cultivars ranged from 222 to 258 kg/ha. Sparta showed the greatest dry matter yield (35.79 Mg/ha), followed by Akela, Hallayuchae, Velox, and Ramon. As N rate increased, crude protein content linearly increased but crude fiber content declined curvilinearly. Akela and Sparta had higher protein content than the other cultivars did. The forage cultivars had lower crude fiber content than the oilseed cultivar Hallayuchae did. Our results demonstrated that Sparta was best adapted to Cheju area and the optimum N rate for Sparta was about 220kg/ha.

• Journal of Environmental Science International
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• v.12 no.10
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• pp.1085-1093
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• 2003

This study was conducted to investigate anoxic-RBC (rotating biological contactor) and its application in advanced municipal wastewater treatment process to remove biologically organics and ammonia nitrogen. Effluent COD and nitrogen concentration increased as the increase of volumetric loading rate. But, the concentration changes of NO$_2$$\^$-/ -N and NO$_3$$\^$-/ -N were little, as compared to COD and NH$_4$$\^$+/ -N. When the volumetric loading rate increased, COD removal efficiency and nitrification appeared very high as 96.7∼98.8% and 92.5∼98.8%, respectively. However, denitrification rate decreased to 76.2∼88.0%. These results showed that the change of volumetric loading rate affected to the denitrification rate more than COD removal efficiency or nitrification rate. The surface loading rates applied to RBC were 0.13～6.0lg COD/㎡-day and 0.312∼1.677g NH$_4$$\^$+/-N㎡-day and they were increased as the increase of volumetric loading rate. However, the nitrification rate showed higher than 90%. The thickness of the biofilm in RBC was 0.130 ∼0.141mm and the density of biofilm was 79.62∼83.78mg/㎤. They were increased as surface loading rate increased. From batch kinetic tests, the k$\_$maxH/ and k$\_$maxN/ were obtained as 1.586 g C/g VSS-day, and 0.276 g N/g VSS-day, respectively. Kinetic constants of denitrifer in anoxic reactor, Y, k$\_$e/, K$\_$s/, and k were 0.678 mg VSS/mg N, 0.0032 day$\^$-1/, 29.0 mg N/l , and 0.108 day$\^$-l/, respectively. P and K$\_$s/, values of nitrification and organics removal in RBC were 0.556 g N/㎡-day and 18.71 g COD/㎡-day, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.46-50
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• 2005

This study was carried out to investigate the proper nitrogen fertilizer level at reclaimed saline land in the southwestern area of Korea from 2002 to 2004. The rice cultivars tested were Samcheonbyeo(Early maturing one), Nampyeongbyeo (Medium maturing one) and Hwaseongbyeo(Mid-late maturing one). The results aye summarized as follows: The more the nitrogen level, the more number of panicle and spikelet per unit area was. But, ripened grain rate and 1000-grain weight were decreased at higher nitrogen level. As higher nitrogen level, head rice rate was decreased and protein content was increased. But, amylose content wasn't differ among the nitrogen fertilizer application levels. As increase nitrogen level in head rice yield increased up to 12 kg/10a, 11 kg/10a, in Samcheonbyeo, Hwaseongbyeo and Nampyeongbyeo, respectively. But there wasn't different more than it. Consequently, considering the yield of head rice, ripened grain rate and rice quality. The proper nitrogen fertilizer application level was 11-12 kg/10a at reclaimed saline land in the southwestern area of Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.1
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• pp.23-27
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• 1990

To elucidate the influence of nitrogen application rate on cool tolerance at the booting stage and respiratory activity of anther at the heading stage in the rice plants, the relationships among nitrogen content in the leaf blade and leaf sheath+culm at young microspore stage, cool tolerance at the booting stage and respiratory activity of anther at the heading stage were investigated for 3 rice cultivars-Yeomyungbyeo, Unbongbyeo and Milyang 23. Nitrogen content in the leaf blade at the young microspore stage was negatively correlated with respiratory rate of anther at the heading stage and fertility index, respectively. Respiratory activity of anther at the heading stage with 10ppm nitrogen application was higher than that of anther with 100ppm nitrogen application. On the Arrhenius plot of respiratory activity of anther at the heading stage, Yeomyungbyeo and Unbongbyeo showed a break at 18$^{\circ}C$ and 18.5$^{\circ}C$, respectively, with 100ppm nitrogen application, but did not show a break in respiratory activity of anther with 10ppm nitrogen application, while Milyang 23 showed a break at 20.5$^{\circ}C$ and 21$^{\circ}C$ with 10ppm and 100ppm nitrogen application, respectively. The highest correlation coefficient between fertility and respiratory rate of anther at the heading stage was shown at 20$^{\circ}C$ in the temperature range of 15$^{\circ}C$-30$^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1186-1192
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• 2005

The relationship between bacteria and anaerobic archaea, sludge yield coefficient and nitrogen removal rate were investigated in intermittent aeration systems(I/A) with added archaea, I/A and conventional activated sludge system. As the archaea solution was added to the I/A reactor, organic removal rate as well as nitrogen removal rate increased. Also, sludge production rate in I/A system added the archaea was maintained lower than other systems because sludge yield coefficient was decreased due to the role of anaerobic archaea such as anaerobic degradation of organics. The experimental data supported the possibility of symbiotic activated sludge system with anaerobic archaea under intermittent aeration, leading to the enhanced nitrogen removal. Crucial results to be presented are: 1) specific oxygen utilization rate(SOUR) of the I/A-arch system was $2.9\;mg-O_2/(g-VSS{\cdot}min)$. SOUR and nitrification rate of the sludge from the I/A-arch system was higher than those from the I/A and A/S reactors. 2) Removal efficiencies of $TCOD_{Cr}$ in the I/A-arch, I/A and A/S reactors were 93, 90 and 87%, respectively. 3) Nitrification occurred successfully in each reactor, while denitrification rate was much higher in the I/A-arch reactor. Efficiencies of TN removal in the I/A-arch, I/A and A/S reactors were 75, 63 and 33%, respectively.