• Korean Journal of Soil Science and Fertilizer
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• 제41권3호
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• pp.164-169
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• 2008

This experiment was carried out to find the growth response and changes of nitrate and soluble sugar content in tomato leaves with salt stress. Tomato (Solanum lycopericum) seedlings were grown under different electrical conductivity (EC) levels adjusted with $CaCl_2$ as 1, 2, and $6dS\;m^{-1}$. The growth response and contents of nitrate and soluble sugar in tomato plants were examined at 7 and 14 days after salt treatment. Leaf area and dry weight ratio of shoot to root of tomato plants were decreased as EC level increased. Photosynthetic rate of leaves was reduced under high EC level due to the stomatal closure and the reduction of transpiration rate. The soluble sugar and starch content were lower in the tomato leaves grown under high EC level. Total nitrogen and nitrate contents were decreased in high EC level, whereas the ammonium content was increased. High-salt stress induced the accumulation of salt crystal in mesophyll cells of tomato leaf.

• Korean Journal of Soil Science and Fertilizer
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• 제41권1호
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• pp.44-49
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• 2008

Sufficient inorganic nitrogen supply for crop growth is crucial for economically sustainable organic farming. The effects of an application of cover crop biomass on crop growth, nitrogen utilization and carbohydrate composition were investigated during early stage. Short-term changes in soil nitrogen after incorporating fresh hairy vetch and rye shoots were measured. The inorganic nitrogen from cover crops reached the peak at 15 ($NH_4-N$) and 24 ($NO_3-N$) days after incorporation, and then decreased rapidly. The highest concentration of soil nitrate showed at 27 days of incorporation in hairy vetch and at 18 days in rye, and three fold differences exhibited between two treatments. Crop growth under hairy vetch or rye incorporation significantly differed. At 20 DAT, dry matter production in NPK and hairy vetch was about two fold greater than that in rye. Difference in decomposing rates of hairy vetch and rye had also influence on nitrogen status in leaves and roots of pepper plants. Total nitrogen was greater in NPK and hairy vetch than in rye until 20 DAT, whereas inorganic nitrogen (nitrate and nitrite) concentration was higher in rye. Temporal changes in soluble sugars and starch in pepper plants among treatments were similar, although difference in the amount existed. It was suggested that hairy vetch as an alternative nitrogen source promoted crop growth and mineral utilization during early growth stage, whereas an obvious effect in rye was not found.

• Korean Journal of Organic Agriculture
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• 제25권2호
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• pp.373-386
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• 2017

The study was conducted to investigate seasonal nutrient dynamics in rice-cultivated soils collected from farmhouses of three large-scale environment-friendly agricultural districts (LEAD), Jangheung, Suncheon, and Okcheon in which environmental-friendly agriculture has been exemplarily practiced in Korea. Among three districts, Crop- livestock cycling organic farming system had been introduced only in Jangheung. pH and EC of farmhouse soils of three LEADs were ranged between 5.5 - 6.7 and $0.4-1.0dS\;m^{-1}$ from March to September, respectively. T-N was observed to be high on the farmhouse soil in Suncheon and K was observed to be lowest on farmhouse soil in Okcheon. Concentration of $NH_4-N$ in soil was observed to be highest on June, in particular on the farmhouse in Jangheung, but rapidly decreased due to the loss of fertilizer applied in Spring. Yield and harvest index were the highest on the farmhouse in Okcheon in which total annual gross production $ha^{-1}$ was nearly three time higher than those of other two farmhouses. Farmhouse soil of Okcheon was maintained the highest seasonal nutrient balance due to the high input of fertilizer. It was estimated that K balance in the farmhouse soil in Suncheon dropped to $-60kg\;ha^{-1}$ on September, and it might have some effect on the less rice productivity due to K deficiency. Farmhouse soil in Jangheung was maintained low seasonal balance of T-N and P but showed the highest N use efficiency in the rice grain. Based on above-mentioned results, we think Jangheung farmhouse can be recommended as a model farmhouse of LEADs.

• Korean Journal of Medicinal Crop Science
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• 제11권2호
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• pp.161-166
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• 2003

Korean ginseng(Panax gmseng C.A. Meyer) is very difficult to obtain stable production of qualified ginseng roots because of variable stresses in soil environments. In environment stresses, soil condition is the most important factor, among which nutrients, especially inorganic materials such as N, P, K, Ca, Mg, Fe, etc., influence greatly on the ginseng growth. However, present ginseng field soils in Korea contain so much amount of such inorganic materials that a variety of remarkable disorders were noted in many ginseng plantations, resulting in decrease of qualitative ginseng production. Therefore, it is required to search for genetic resources and genes tolerant to salt stress for the development of ginseng cultivars. Selection of stress-tolerant ginseng lines in fields is very difficult because it is almost impossible to control properly the environmental conditions of soil. On the contrary, it can be studied with ease to search for stress-tolerant ginseng lines through in vitro culture because of easy manipulation of stress conditions. Murashige & Skoog(MS) media with 2.5 folds of $KNO_3,\;NH_4NO_3,\;MgSO_4\;7H_2O,\;KH_2PO_4,\;and\;CaCl_2\;2H_2O$ was established for the selection of ginseng lines tolerant to salt stress under the embryo culture.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.204-205
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• 2011

In thin film silicon solar cells, p-i-n structure is adopted instead of p/n junction structure as in wafer-based Si solar cells. PECVD is a most widely used thin film deposition process for a-Si:H or ${\mu}c$-Si:H solar cells. For best performance of thin film silicon solar cell, the dopant profiles at p/i and i/n interfaces need to be as sharp as possible. The sharpness of dopant profiles can easily achieved when using multi-chamber PECVD equipment, in which each layer is deposited in separate chamber. However, in a single-chamber PECVD system, doped and intrinsic layers are deposited in one plasma chamber, which inevitably impedes sharp dopant profiles at the interfaces due to the contamination from previous deposition process. The cross-contamination between layers is a serious drawback of a single-chamber PECVD system in spite of the advantage of lower initial investment cost for the equipment. In order to resolve the cross-contamination problem in single-chamber PECVD systems, flushing method of the chamber with NH3 gas or water vapor after doped layer deposition process has been used. In this study, a new plasma process to solve the cross-contamination problem in a single-chamber PECVD system was suggested. A single-chamber VHF-PECVD system was used for superstrate type p-i-n a-Si:H solar cell manufacturing on Asahi-type U FTO glass. A 80 MHz and 20 watts of pulsed RF power was applied to the parallel plate RF cathode at the frequency of 10 kHz and 80% duty ratio. A mixture gas of Ar, H2 and SiH4 was used for i-layer deposition and the deposition pressure was 0.4 Torr. For p and n layer deposition, B2H6 and PH3 was used as doping gas, respectively. The deposition temperature was $250^{\circ}C$ and the total p-i-n layer thickness was about $3500{\AA}$. In order to remove the deposited B inside of the vacuum chamber during p-layer deposition, a high pulsed RF power of about 80 W was applied right after p-layer deposition without SiH4 gas, which is followed by i-layer and n-layer deposition. Finally, Ag was deposited as top electrode. The best initial solar cell efficiency of 9.5 % for test cell area of 0.2 $cm^2$ could be achieved by applying the in-situ plasma cleaning method. The dependence on RF power and treatment time was investigated along with the SIMS analysis of the p-i interface for boron profiles.

• Korean Journal of Food Science and Technology
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• 제12권3호
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• pp.209-215
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• 1980

Proteases from papaya latex were partially purified by ammonium sulfate precipitation and separated into two fractions (Fraction I and II ) by carboxymethyl cellelose column chromatography. Each fraction, mixture of the two fractions, and crude extract of the papaya latex at pH 7.0 were inactivated at the range of $60{\sim}90^{\circ}C$ and thermal properties of the enzymes were investigated. In the thermal inactivation of fraction I, the enthalpy of activation was 89.5 kJ/mol; the entropy of activation, -44.0 J/mol K; the free energy of activation, 104.6 kJ/mol; z-value, $25^{\circ}C$. For fraction II, the enthalpy of activation was 96.5 kJ,/mol; the entropy of activation, -22.0 J/mol K; the free energy of activation, 104.0 kJ/mol; z-value, $23^{\circ}C$. For the mixture of fraction I and II, the enthalpy of activation was 90.9 kJ/mol; the entropy of activation, -38.8 J/mol·K; the free energy of activation, 104.2 kJ/mol; z-value, $24.6^{\circ}C$. For crude extract, the enthalpy of activation was 113.8 kJ/mol; the entropy of activation, 22.0 J/mol·K; the free energy of activation, 106.2 kJ/mol; z-value, $23.2^{\circ}C$. It was indicated that the fraction I was more heat-stable than the fraction II and this suggested that the thermal stability of the proteases in papaya latex is probably due to the fraction I.

• Journal of The Korean Society of Grassland and Forage Science
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• 제6권3호
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• pp.151-156
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• 1986

There are differences in recommendations in the USA as to whether nitrogen fertilizer should be applied when establishing alfalfa (Medicago sativa L). The reason for not applying nitrogen is because some researchers found the addition of nitrogen reduced nodulation of alfalfa plants. A replicated experiment was conducted under controlled environmental conditions at the University of Nevada-Reno, Reno, Nevada, USA, to determine the effects of nitrogen application on seedling growth and nodulation of alfalfa when grown in a cool environment. A sterile sand was used in the growing media to which a complete nutrient solution minus nitrogen was applied volumetrically to each pot daily. Half of the pots received $NH_4NO_3$, at the rate of 11.2 kg/ha, at seeding and two and four weeks after planting, giving a total nitrogen application rate of 33.6 kg/ha. Rhizobia inoculant (R-12) consisted of a mixture of strains 171-15a. 1682c and 80 PI 265 of Rhizobium meliloti. Inoculant was applied to the seeds prior to planting and to the sand media at two and four weeks after seeding. Twenty seeds were planted in pots 14.0 cm in diameter and 11.5 cm deep. Seedlings were thinned after emergence to ten plants per pot. They were grown in a controlled environment chamber with a 16-hour light period. Soil temperatures at 6 cm depth ranged from $5.7^{\circ}C\;to\;21.5^{\circ}C$ and had a daily mean of $16.2^{\circ}C$ Plants were harvested at weekly intervals for seven weeks at which time root, shoot and total length, dry weight, volume and number of nodules per plant were determined. Root, shoot and total length were not affected by nitrogen fertilizer. However, application of nitrogen increased the size of the seedlings as determined by dry weight and volume when compared to plants which were not fertilized. This indicates that rhizobia did not fix enough atmospheric nitrogen to promote good growth. Nitrogen application resulted in significantly more nodules per plant. The effect of nitrogen fertilizer became more apparent as the plant became older. Results of this experiment show there are benefits from applying nitrogen at a low rate when establishing alfalfa under a cool environment.

• Korean Journal of Food Science and Technology
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• 제32권3호
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• pp.640-645
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• 2000

The effect of gamma-irradiation on the quality changes of the grain shape improved Meju was studied. Meju was prepared, irradiated at 0, 5, 10 and 20 kGy, and then stored at $25^{\circ}C$ for six months. The results showed that the fungi and acid producing bacteria were completely eliminated by gamma-irradiation with dose of 10 kGy or higher and the Bacillus was decreased by 5 log cycles with dose of 10 kGy. The $D_{10}$ values of the fungi, Bacillus and acid producing bacteria were 0.79, 2.28 and 1.17 kGy, respectively. Also, the microorganisms that survived irradiation was decreased significantly with the duration of storage period. The $NH_3-nitrogen$, negative factors of quality of Meju, and browning were repressed and the protease activity and pH were not affected by gamma-irradiation. Therefore, it was considered that the Meju treated with gamma-irradiation maintained better quality than that of the control with storage.

• Journal of the Semiconductor & Display Technology
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• 제4권4호
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• pp.19-26
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• 2005

The process optimization of ozone concentration and half life time was investigated in ultra pure water and alkaline solutions for the wet cleaning of silicon wafer surface at room temperature. In the ultra pure water,. the maximum concentration (35 ppm) of ozone was measured at oxygen flow rate of 3 liters/min and ozone generator power over 60%. The half life time of ozone increased at lower power of ozone generator. Additive gases such as $N_2$ and $CO_2$ were added to increase the concentration and half life time of ozone. Although the maximum ozone concentration was higher with the addition of $N_2$ gas, a longer half life time was observed with the addition of $CO_2$. When $NH_4OH$ of 0.05 or 0.10 vol% was added in DI water, the pH of the solution was around 10. The addition of ozone resulted in the half life time less than 1 min. In order to maintain high pH and ozone concentration, ozone was continuously supplied in 0.05 vol% ammonia solutions. 3 ppm of ozone was dissolved in ammonia solutions. The static contact angle of silicon wafer surface became hydrophilic. The particle removal was possible alkaline ozone solutions. The organic contamination can be removed by ozonated ultra pure water and then alkaline solution containing ozone can remove the particles on silicon surface at room temperature.

• Microbiology and Biotechnology Letters
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• 제16권2호
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• pp.92-97
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• 1988

Cysteinylglycinase was partially purified from Proteus mirabilis by consecutive procedure. The specific activity was increased about 16-fold to that of cell-free extract. The enzyme was found rather unstable on ammonium sulfate precipitation ann the precipitated enzyme protein became partially insoluble during dialysis. The precipitated enzyme was found to be solubilized by treatment of 4% Triton X-100 effectiviely, The optimum temperature and pH of the enzyme activity were 35$^{\circ}C$ and 7.3, respectively. After heat treatment of the enzyme at 5$0^{\circ}C$ for 30 min, it lost the activity to 70%. The enzyme was stable at pH 7.0-8.0. The molecular weight of the cysteinylglycinase was found to be about 190,000 by Sephadex G-150 gel filtration. The enzyme was activated by the addition of Mn$^{2+}$ and $Mg^{2+}$ ions. The maximal activation was obtained in preincubation with $Mg^{2+}$ ion for 30 min. The enzyme catalyzed the hydrolysis of various dipeptides and tripeptides. The Km and Vmax values for cysteinylglycine were 1.60 mM and 0.24 m unit/ mg, respectively.