• Korean Journal of Agricultural Science
• /
• v.41 no.4
• /
• pp.291-298
• /
• 2014

Plastic film houses are directly associated with increases in plant growth and yield of vegetable crops through a year round cultivation, however, at the same time temperature stresses are one of fates which are difficult to avoid during crop growth. The objective of this study was to examine the translocation and distribution of minerals (N, P, K) and carbohydrates as well as seasonal fluctuation of mineral uptake and carbohydrate production in cucumber plant grown under moderately high temperature. The temperature treatments consisted of 2-layers film houses (optimal temp.) and 3-layers (high temp.). Shoot growth of cucumber plants were linearly increased until 14 weeks after transplanting (WAT) without any significant difference between both temperatures, and the slowdown was observed from 16 WAT. The level of soluble sugar and starch was slightly greater in optimal temperature compared to the high. Cumulative accumulation of soluble sugar was significantly different before and after 12 WAT in both treatments, whereas starch level represented a constant increase. Monthly production of soluble sugar reached the peak between 12 to 16 WAT, and starch peaked between 4 to 8 WAT and 12 to 16 WAT. Total uptake of N, P and K in optimal and high temperature conditions was $18.4g\;plant^{-1}$ and 17.6 for N, 4.7 and 5.1 for P, and 37.7 and 36.2 for K, respectively, and the pattern of monthly N uptake between optimal and high temperatures was greater in early growth stage, whereas was greater in mid growth stage in both P and K. Thus, this study suggests that moderately high temperature influences much greater to photosynthesis and carbohydrate production than plant biomass and mineral uptake. On the basis of the present result, it is required to indentify analysis of respiration rates from plant and soil by constantly increasing temperature conditions and field studies where elevated temperatures are monitored and manipulated.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.1
• /
• pp.104-111
• /
• 2009

This paper shows the behaviors of macro- and micro-structures and mechanical properties for specimen's welding region welded by FSW. according to welding conditions with 5mm thickness aluminum 5083O alloy plate. It apparently results in defect-free weld zone in case traverse speed was changed to 32 mm/min under conditions of anti-clockwise direction and tool rotation speed such as 800 and 1250 rpm with tool's pin diameter of 5 ${\Phi}mm$ and shoulder diameter of 20 ${\Phi}mm$, pin length of 4.5 mm and tilting angle of $2^{\circ}$. The ultimate stress of ${\sigma}_T=331$ MPa and the yield point of 147 MPa are obtained at the condition of the travel speed of 32 mm/min with the tool rotation speed of 1250 rpm. There is neither voids nor cracks on bended surface of $180^{\circ}$ after bending test. The improvement of toughness after impact test was found. The lower rotating and traverse speed became, the higher were yield point, maximum stress and elongation(%) with the stresses and the elongation(%) versus the traverse speed diagram. Vickers hardness for cross section of welding zone were also presented. The typical macro-structures such as dynamically recrystallized zone, thermo-mechanically affected zone and heat affected zone and the micro-structures of the transverse cross-section were also showed. However, the author found out that the region of 6mm far away from shoulder circumference was affected by friction heat comprehensively, that is, hardness softened and that part of micro-structures were re-solid-solution or recrystallized, the author also knew that there is no mechanically deformation on heat affected zone but there are the flow of plastic deformation of $45^{\circ}$ direction on thermo-mechanically affected zone and the segregation of Al-Mg on nugget. The solid solution wt(%) of parent material as compared against of friction stir welded zone was comprehensively changed.

• Journal of the Korean Applied Science and Technology
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2009

Nowadays, Tra catfish fat is given attention as an appropriate material for biodiesel production in Vietnam. The aim of this work is to investigate the optimal conditions of refining biodiesel and recovering glycerin by the transesterification from Tra catfish fat using KOH catalyst. As our results, the yield of transesterification was achieved to 94.17% at $50^{\circ}C$ for 45 min with 6:1 molar ratio of methanol to fat in the presence of 0.8% KOH catalyst, and wherein the biodiesel was refined by washing with distilled water at $70^{\circ}C$ and dried in a microwave oven. The yield of raw glycerin recoveries from the transesterification process was 78.58%. The purity of raw glycerin was 84.14% by the conditions of neutralization state with $H_{3}PO_{4}$ solution (pH = 5), $70^{\circ}C$, and 60 min. Activated carbon (3.0 wt.%) was used for the bleaching process at $80^{\circ}C$ for 20 min. The biodiesel was obtained in accordance with for ASTM D 6751 (biodiesel standard). The ash and water of raw glycerins were 7.32 and 8.01%, respectively, and implied that the raw glycerin is very promising candidate to be used as a raw material for textile and cosmetic industries.

• KSBB Journal
• /
• v.14 no.2
• /
• pp.241-247
• /
• 1999

Experimental studies were carried out to optimize the culture conditions of Corynebacterium diphtheriae for the production of diphtheria toxin. A new media which does not contain any meat digest products was selected. The main ingredient of new medium was enzymatic digests of casein known as NZ-Case. In fermenter experiments, the toxin production was increased with the increase of cell growth. The optimum initial pH of media, air flow rate and agitation speed were 7.0, 0.22, vvm and 400 rpm, respectively. The contents of iron and calcium-phosphate precipitate were important for maximal cell growth and toxin production. The optimum concentration of iron was 0.3 mg/L and calcium-phosphate precipitate could serve in gradual supply of iron to maintain the optimal culture condition which is required for enhanced yield of toxin production. In potency test, the potency of toxoid from fermentor culture was higher than that from static culture. When diphtheria toxin is produced by fermentor culture, it is possible to produce higher levels of toxin and better toxoid quality in terms of safety, yield, productivity and immunity.

• Journal of Crop Science and Biotechnology
• /
• v.11 no.2
• /
• pp.111-118
• /
• 2008

Soybean is sensitive to waterlogging stress, leading to reduce their growth and yield significantly. The objective of this study was to characterize the relative sensitivities of biomass accumulation and specific nodule activity under waterlogging stress between supernoduating mutants, 'SS2-2' and 'Sakukei 4' and their wild-type soybeans, 'Sinpaldalkong 2' and 'Enrei', respectively. Flooding treatment was performed to soybean plants grown in a pot by waterlogging for 15 days from the beginning bloom(R1) stage under natural light. The nodule number and weight were considerably decreased by waterlogging stress. The bleeding sap rate of waterlogging soybean plants was decreased by 78-80% in supernodulating mutants and 65-74% in their wild types compared to control plants. The relative ureide-N content was also decreased by waterlogging and the reduction was high in supernodulating mutants. This may cause the massive reduction of shoot and root dry weight and leaf area in waterlogged soybean plants. There was a varietal difference in response to the waterlogging stress. During the waterlogging, supernodulating mutants maintained higher spad value than their wild types. Particularly, the difference between soybean varieties was clear in low rank leaves from the top. Also, supernodulating mutants showed a weak waterlogging tolerance than their wild types. Under waterlogging conditions, massive nodules were considerably destroyed and specific nodule activity after waterlogging may not be recovered when compared to their wild-type soybeans. Supernodulating mutants showed lower seed yield than their wild types in waterlogging conditions.

• Korean Journal of Food Science and Technology
• /
• v.15 no.1
• /
• pp.51-55
• /
• 1983

It was investigated under several cultural conditions to produce biomass directly from starch by an strictly aerobic and amylolytic yeast, Sporobolomyces holsaticus FRI Y-5. Its optimal temperature and initial pH of medium for growth were $23^{\circ}C$ and 6.9, respectively. Activation energy, Ea, for growth was calculated to be 17.33 Kcal/mole from the Arrhenius relationship. When each of 13 nitrogen sources was added to the basal medium, $(NH_2)_2CO$ had the best effect, on which concentration of cell after 3 day incubation was 10.6 g/l and cell yield was 0.451. The yeast growth was affected by $MgSO_4,\;K_2SO_4\;and\;ZnSO_4$ as a mineral source and was best on the medium containing all of them. The addition of yeast extract (5g/l) could enhance the production of biomass and cell yield to 77% and 32%, respectively.

• Journal of Environmental Science International
• /
• v.27 no.8
• /
• pp.631-639
• /
• 2018

A Cultivation method to minimize the damage caused by high temperatures was studied by investigating the effects of groundwater cooling treatment on the growth, yield, and quality of strawberries. In the groundwater cooling treatment, the daily average temperature of the rhizosphere was reduced from $26.9^{\circ}C$ to $24.9^{\circ}C$. The root length increased by 0.3-9.2 cm, depending on the cultivar and growth period. The leaf number, leaf area, leaf length, leaf diameter, and plant height also increased, especially in the cultivars 'Seolhyang' and 'Maehyang', resulting in higher fresh and dry weights. The number of fruit per plant increased from 7.7 to 12.5 in 'Seolhyang', and the fruit weight increased by 0.3 g in 'Seolhyang' and 1.3 g in 'Maehyang'. The fruit hardness increased, but no significant difference in fruit coloration was observed. The sugar content of the fruit was improved by $0.2-0.3^{\circ}Brix$. Therefore, groundwater cooling of the rhizosphere was effective in improving the growth and productivity of strawberries under abnormally high temperature conditions and can be considered a cost-efficient cooling system.

• Ocean and Polar Research
• /
• v.32 no.2
• /
• pp.157-164
• /
• 2010

A marine alga, Spirulina maxima, was extracted under high pressure and low temperature conditions at 500 MPa and $60^{\circ}C$ for 5 and 10 min. A high pressure of 500 MPa was applied to improve process yields because of low temperature extraction. This method resulted in highest higher extraction yield of 26.1% (w/w) in comparison to those results obtained from conventional extraction methods which produced a yield of 17.6% (w/w) from water. The extracts from this process also showed 19% of low cytotoxicity against human normal fibroblast cells in adding 1.0 mg/ml of the highest concentration. The crude extract significantly reduced the production of Prostaglandin $E_2$ ($PGE_2$) from CCD-986sk cells and increased nitric oxide production by macrophages. These higher activities of enhancing skin immune functions were found to have high antioxidant extract properties, like a 98% increase in DPPH radical scavenging activity. The extracts from the high pressure process showed a higher elution of active components than other processes and generated new compounds based on HPLC analysis. This clearly indicates that the extracts from high pressure and low temperature conditions have higher skin immune activation properties that have not been previously reported.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.11
• /
• pp.118-123
• /
• 2017

To manufacture MG-Si (Metallurgical grade silicon) for use in various industries, Acid leaching experiments were performed to remove aluminum (Al) and iron (Fe), which are the most common impurities found in the silicon raw material. The silicon raw material was reacted with five types of acids (HCl, HF, H2SO4, HNO3, H3PO4) at 1, 2, 4, and 6M; 1M HF showed the highest Al and Fe removal rates, 97.9% and 95.2%, respectively. HF, however, resulted in an 18% reduced yield due to the silicon corrosion properties. To minimize the yield reduction, 2M HCl, which has a second removal ratio result, was mixed with 1M HF and applied to the silicon raw material. The experiment was conducted to select the optimal conditions for the mixed solution, which were $80^{\circ}C$ and 2hr. Under the optimal conditions, the residual Al and Fe concentrations were 141 ppmw and 93 ppmw, respectively, and it very easy to produce MG-Si with 3N grade purity.

• Microbiology and Biotechnology Letters
• /
• v.37 no.3
• /
• pp.226-230
• /
• 2009

Rice straw was pretreated using dilute sulfuric acid at reaction conditions covering two levels of reaction temperature (140, $150^{\circ}C$) and five levels of acid concentrations ($1.0{\sim}3.0%wt$). The production and decomposition rates of major components of rice straw indicating glucose, xylose, galactose and arabinose were investigated. The production rate of arabinose and the decomposition rate of xylose were greatest among them. The maximum attainable hemicellulose (xylose+galactose+arabinose) yield was about 80%. High acid concentration appears to favor the maximum yield but high temperature does not. The optimum condition was found to be $140^{\circ}C$, 2.5% and 20 minutes. The maximum glucose yields were almost same, around $16{\sim}18%$, regardless of reaction conditions.