• Journal of computational fluids engineering
• /
• v.11 no.1 s.32
• /
• pp.57-66
• /
• 2006

An optimal shape design approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is employed to capture strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method For code validation, the result of the flow solver is compared with experiment data and other computational results of bench marking test. To study the influence oj turbulence models and grid refinement on the duct flow analysis, the results from several turbulence models are compared with one another and the minimum number of grid points, which can yield an accurate solution is investigated The adjoint variable code is validated by comparing the complex step derivative results. To realize a sufficient and flexible design space, NURBS equations are introduced as a geometric representation and a new grid modification technique, Least Square NURBS Grid Approximation is applied With the verified flow solver, the sensitivity analysis code and the geometric modification technique, the optimization of S-shaped intake is carried out and the enhancement of overall intake performance is achieved The designed S-shaped duct is tested in several off-design conditions to confirm the robustness of the current design approach. As a result, the capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional highly turbulent internal flow design and off-design conditions.

• Composites Research
• /
• v.23 no.5
• /
• pp.1-7
• /
• 2010

To increase the adhesive strength of acrylonitrile butadiene rubber(NBR) and steel plate, the atmospheric pressure flame plasma(APFP) treatment device is applied. The effect of various conditions(processing velocity and distance) is experimentally investigated to ascertain the optimum conditions to yield the best adhesive properties. It is found that the optimum distance between burner port and steel plate is 40mm and the optimum processing velocity is 50m/min at given condition. When the surface is coated twice with the bonding agent, the adhesion strength of APFP treated steel plate is increased to about 20.5%. It suggests that the surface modification of steel by flame plasma treatment at atmospheric pressure is a proper and applicable method to improve the adhesion strength between steel and rubber.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.33 no.11
• /
• pp.869-875
• /
• 2009

The purpose of this paper is to investigate the optimal condition of the syngas production by reforming of propane using Gliding arc plasma reformer. The gliding arc plasma reformer in 3 phases has been newly designed and developed with a quick starting and fast response time. It can be applicable to the various types of fuels (Hydrocarbons $C_xH_y$), and it has a high conversion rate of fuels and high production of hydrogen. The parametric screening studies were carried out according to the changes of a steam feed amount i.e., steam/carbon ratio, total gas flow rate and input electric power. The optimum operating conditions were S/C ratio 2.8, total gas flow rate of 14 L/min and input electric power of 2.4 kW. The result of optimum operating conditions showed the 55 % $H_2$, 14 % CO, 15 % $CO_2$, 10 % $C_3H_8$ and 4 % $CH_4$. Also, $C_3H_8$ conversion, $H_2$ yield and $H_2$ selectivity were 90 %, 42 %, 15 %, respectively. The energy efficiency and specific energy requirements were 37 % and 334 kJ/mol respectively.

• Korean Journal of Microbiology
• /
• v.19 no.4
• /
• pp.163-173
• /
• 1981

The distribution of methanol-assimilating yeasts on three different sources (elm bark, soil and fresh-water mud) and the growth conditions of a new strain of Candidaboidinii (SIO) wereexamines. From 150 samples, 91 methanol yeasts were isolated through enrichment culture ; they were identified as 77 strains of Candida boidinii including four new strains, 5 isolates of Torulopsis pinus, 3 strains of Hansenula polymorpha and one sstrain of Pichia pastoris respectively. The comparison of these yeasts with three sources indicated that decaying bark of elm tree other two, and that Gandida boidinii was most frequently distributed in all three sources. Four new strains of Candida boidinii were freshly isolated and their taxonomical properties were discussed. Of them, SIO strain was selected and characterized for its growth on methanol. This yeast could grow well on less than 1%(v/v) methanol. However, its growth was inhibited at 10% methanol. The cell yield was 3.1g (dry weight) per 1000ml of mineral mediurr, containing 1%(v/v) methanol as well as 01.% yeast extract as additive. The concentration of 0.1% yeast extract appears to be effective for the biomass production. Optimum conditions for growth on methanol was found to be : $28^{\circ}C,\;NH_4^+$ as nitrogen sources, thiamine as vitamin, and pH 4.5 to 6.0. The cell composition was as follows : crude protein and nucleic acids were 54% and 7% respectively. The amino acids were also described.

• KSBB Journal
• /
• v.23 no.2
• /
• pp.131-134
• /
• 2008

Tea seed extract, a byproduct of tea processing, contains two kaempferol glycosides, camelliaside A and camelliaside B. Kaempferol was produced by enzymatic hydrolysis of glycosides. Optimum reaction conditions were investigated. $Pectinex^{(R)}100L$ was effective, producing kaempferol in 48 hrs. Optimum temperature and pH were $40^{\circ}C$ and 4, respectively. Ratio of substrate and enzyme affected the yield. Under optimum conditions, 1.6g kaempferol per 1 kg tea seed extract was produced and 80% of kaempferol precipitated. This result shows that kaempferol could be produced mildly and effectively using tea-processing byproduct.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.1
• /
• pp.11-16
• /
• 2001

CuNi alloy films are deposited by co-sputtering of dual targets (Cu and Ni, respectively). Effects of the co-sputtering conditions, such as powers applied to the targets, deposition pressures, and substrate temperatures, on the structural and electrical properties of deposited films are systematically investigated. The composition ratio of Ni/Cu is almost linearly decreased by increasing the DC power applied to the Cu target from 25.6 W to 69.7 W with the RF power applied to the Ni target unchanged(140 W). it is noted that the chamber pressure during deposition and the film thickness give rise to a change of the Ni/Cu ratio within the films deposited. The former may be due to a higher sputtering yield of Cu atom and the latter due to the re-sputtering phenomenon of Cu atoms on the surface of deposited film. The film deposited at higher pressures or at lower substrate temperatures have a smaller crystallite size, a higher electrical resistivity, and much more voids. This may be attributed to a lower surface mobility of sputtered atoms over the substrate.

• Journal of the Korean Society of Combustion
• /
• v.14 no.2
• /
• pp.1-9
• /
• 2009

New way to effectively capture $CO_2$ in coal fired power plant is the combustion of coal using oxy-fuel technology. Combustion characteristics of Minco sub-bituminous coal at oxy-fuel conditions using TGA and drop tube furnace (DTF) were included activation energy about the char burnout, volatile yield and combustion efficiency of raw coal, the porosity of pyrolyzed char and fusion temperature of by-product ash. TGA result shows that the effect of $CO_2$ on combustion kinetics reduces activation energy by approximately 7 kJ/mol at air oxygen level(21% $O_2$) and decreases the burning time by approximately 16%. The results from DTF indicated similar combustion efficiency under $O_2/CO_2$ and $O_2/N_2$ atmospheres for equivalent $O_2$ concentration whereas high combustion efficiency under $O_2/N_2$ than $O_2/CO_2$ was obtained for high temperature of more than $1,100^{\circ}C$. Overall coal burning rate under $O_2/CO_2$ is decreased due to the lower rate of oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. By-product ash produced under $O_2/CO_2$ and $O_2/N_2$ was similar IDT in irrelevant to $O_2$ concentration and atmospheres gas during the coal combustion.

• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.2
• /
• pp.63-68
• /
• 2008

Hard and brittle materials, such as Ni- and Ti-based alloys, glass, and ceramics, are very useful in aerospace, marine, electronics, and high-temperature applications because of their extremely versatile mechanical and chemical properties. One Ni-based alloy, Inconel 718, is a precipitation-hardenable material designed with exceptionally high yield strength, ultimate tensile strength, elastic modulus, and corrosion resistance with outstanding weldability and excellent creep-rupture properties at moderately high temperatures. However, conventional machining of this alloy presents a challenge to industry. Ultrasonic vibration cutting (UVC) has recently been used to cut this difficult-to-machine material and obtain a high quality surface finish. This paper describes an experimental study of the UVC parameters for Inconel 718, including the cutting force components, tool wear, chip formation, and surface roughness over a range of cutting conditions. A comparison was also made between conventional turning (CT) and UVC using scanning electron microscopy observations of tool wear. The tool wear measured during UVC at low cutting speeds was lower than CT. UVC resulted in better surface finishes compared to CT under the same cutting conditions. Therefore, UVC performed better than CT at low cutting speeds for all measures compared.

• The Plant Pathology Journal
• /
• v.32 no.6
• /
• pp.508-518
• /
• 2016

Early blight of tomato caused by Alternaria solani, is responsible for severe yield losses in tomato. The conidia survive on soil surface and old dry lower leaves of the plant and spread when suitable climatic conditions are available. Macroclimatic study reveals that highest inoculum concentration of Alternaria spores appeared in May 2012 to 2013 and lowest concentration during January 2012 to 2013. High night temperature positively correlated and significantly (P < 0.01) involved in conidial spore dispersal and low relative humidity (RH) displayed significant (P < 0.05) but negative correlation with conidial dispersal. The objective of the study was to modify microclimatic conditions of tomato crop canopy which may hamper conidial dispersal and reduce disease severity. We evaluated effect of marigold intercropping and plastic mulching singly and in consortia on A. solani conidial density, tomato leaf damage and microclimatic parameters as compar to tomato alone (T). Tomato-marigold intercropping-plastic mulching treatment (T + M + P) showed 35-39% reduction in disease intensity as compared to tomato alone. When intercropped with tomato, marigold served as barrier to conidial movement and plastic mulching prevented evapotranspiration and reduced the canopy RH that resulted in less germination of A. solani spores. Marigold intercropping and plastic mulching served successfully as physical barrier against conidial dissemination to diminish significantly the tomato foliar damage produced by A. solani.

• Journal of Plant Biotechnology
• /
• v.4 no.2
• /
• pp.53-58
• /
• 2002

Adverse environmental conditions such as drought, high salt and cold/freezing are major factors that reduces crop productivity worldwide. According to a survey, 50-80% of the maximum potential yield is lost by these "environmental or abiotic stresses", which is approximately ten times higher than the loss by biotic stresses. Thus, improving stress-tolerance of crop plants is an important way to improve agricultural productivity, In order to develop such stress-tolerant crop plants, we set out to identify key stress signaling components that can be used to develop commercially viable crop varieties with enhanced stress tolerance. Our primary focus so far has been on the identification of transcription factors that regulate stress responsive gene expression, especially those involved in ABA-mediated stress response. Be sessile, plants have the unique capability to adapt themselves to the abiotic stresses. This adaptive capability is largely dependent on the plant hormone abscisic acid (ABA), whose level increases under various stress conditions, triggering adaptive response. Central to the response is ABA-regulated gene expression, which ultimately leads to physiological changes at the whole plant level. Thus, once identified, it would be possible to enhance stress tolerance of crop plants by manipulating the expression of the factors that mediate ABA-dependent stress response. Here, we present our work on the isolation and functional characterization of the transcription factors.n factors.