• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.548-554
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• 1994

The high temperature fatigue crack growth behavior of SUS 304 stainless steel at $550^{\circ}C$ and $650^{\circ}C$ was investigated under various kinds of stress ratio and frequency in sinusoidal waveform on the basis of the non-linear fracture mechanics. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at $550^{\circ}C$ were plotted within data band of da/dN-${\triangle}J_f$ relationship for cycle-dependent crack growth. On the basis of static creep and cycle-dependent data band; both time- and cycle-dependent crack growth behavior was observed under loading conditions at $650^{\circ}C$, but cycle-dependent crack growth behavior predominantly appeared and time-dependent crack growth behaviour was little observed under loading conditions at $550^{\circ}C$. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The stripes were found on fracture surface and each stripe was accompanied by a crack tip blunting and an abrupt increase in the load-point displacement. The $J'_{an}$ had a validity in case of $650^{\circ}C, but scarcely had it in case of $550^{\circ}C$.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1933-1938
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• 2004

Nucleate boiling experiments with constant wall temperature of heating surface were performed using R113 for almost saturated pool boiling conditions. A microscale heater array and Wheatstone bridge circuits were used to maintain a constant wall temperature condition and to measure the heat flow rate with high temporal and spatial resolutions. Bubble images during the bubble growth were taken as 5000 frames a sec using a high-speed CCD camera synchronized with the heat flow rate measurements. The geometry of the bubble during growth time could be obtained from the captured bubble images. The bubble growth behavior was analyzed using the new dimensionless parameters for each growth regions to permit comparisons with previous results at the same scale. We found that the new dimensionless parameters can describe the whole growth region as initial and later respectively. The comparisons showed good agreement in the initial and thermal growth regions. The required heat flow rate for the volume change of the observed bubble was estimated to be larger than the instantaneous heat flow rate measured at the wall. Heat, which is different from the instantaneous heat supplied through the heating wall, can be estimated as being transferred through the interface between bubble and liquid even with saturated pool conditions. This phenomenon under a saturated pool condition needs to be analyzed and the data from this study can supply the good experimental data with the precise boundary condition (constant wall temperature).

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.2
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• pp.170-177
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• 1997

Two experiments were conducted to evaluate the effects of different extrusion conditions of corn and soybean meal on physico-chemical properties, ileal digestibility of amino acid and growth performance in weaned pigs. In Expt. 1, to compare physico-chemical properties and ileal digestibility of extruded corn and soybean meal, ground corn (2 mm screen) and soybean meal were separately extruded in four different conditions: (1) no preconditioning, low water supply (3.0 l/min) (NCLW), (2) no preconditioning, high water supply (7.0 l/min) (NCHW). (3) preconditioning (steam 3.0 l/min) with low water supply (3.0 l/min) (CLW), and (4) preconditioning (steam 3.0 l/min) plus high water supply (7.0 l/min) (CHW). Twenty-five cannulated pigs ($L{\times}Y{\times}D$, 7.62 kg BW for soybean meal, 8.80 kg BW for corn) were employed to determine nutrients digestibility of the extruded feedstuffs. In Expt. 2, a total of 90 pogs ($L{\times}Y{\times}D$, 9.18 kg BW) were used for a 28 d feeding trial to compare growth performance of pigs as affected by different extrusion conditions. Before mixing, corn and soybean meal were blended and extruded by the same conditions as described in Expt. 1. corn extruded with NCLW showed the highest (p < 0.05) degree of gelatinization (DG), compared to the lowest values observed for NCHW. Extrusion of corn with preconditioning (CLW and CHW) increased (p < 0.05) the DG as compared to the extrusion condition of NCHW. Extruded SBM with NCLW showed the lowest (p < 0.05) degree of texturization among treatments. The ileal digestibility of GE in SBM was higher with NCHW and CHW as compared to NCLW. The ileal digestibility of CP was lower in extruded corn, but was higher in extruded SBM, compared to untreated sample. Lysine digestibility of extruded corn (except corn with NCHW) was in general significantly improved. Extrusion of SBM resulted in no improvements in ileal digestibility of amino acids, but extruded SBM with NCLW had lower lysine digestibility compared to other treatments. In growth responses, pigs fed a diet with CLW had higher, but not significant, average daily gain (ADG) than other treatments during first 2 weeks. From d 15 to 28, pigs fed a diet with CHW had significantly less (p < 0.05) average daily feed intake (ADFI) than others except NCHW. In conclusion, the proper extrusion condition for corn and SBM in terms of ileal digestibility of amino acids and growth performance of weaning pigs seems to be the combination of preconditioning and a low water supply (3.0 l/min).

• Journal of Wetlands Research
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• v.25 no.3
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• pp.196-204
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• 2023

Eleutherococcus gracilistylus is a designated rare plant by the Korea Forest Service, a deciduous broad leaf shrub native to the Gotjawal region, Jejudo. This study aimed to analyze the growth responses of E. gracilistylus to three environment factors such as light, moisture, and organic matter, and measure its ecological niche breadth. Based on these results, an attempt was made to identify suitable environmental conditions. E. gracilistylus exhibited increased above-ground length, leaf area, and plant leaf weight under intermediate conditions of light availability(L3, 50% of natural light), rather than very high or very low light conditions. Moisture availability and organic matter availability showed variations in growth responses in terms of leaf count and plant leaf weight. Under moisture availability, growth was favorable under or below intermediate conditions (M3, 240ml), while under organic matter availability, growth response was better above intermediate conditions (N3, 12%). Ecological niche breadth showed in the light factor(0.951), the moisture factor(0.977), and the organic matter content one(0.964). These results indicate that the preferred habitat of E. gracilistylus is somewhat shady, slightly dry, and has a lot of nutrients, and that the environmental factor that has the greatest impact on growth is the amount of light, which is considered to be a priority consideration for habitat management in its native area.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1777-1789
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• 2019

Drought is more concerned to be a huge problem for agriculture as it affects plant growth and yield. Endophytic bacteria act as plant growth promoting bacteria that have roles for improving plant growth under stress conditions. The properties of four strains of endophytic bacteria were determined under water deficit medium with 20% polyethylene glycol. Bacillus aquimaris strain 3.13 showed high 1-aminocyclopropane-1-carboxylate (ACC) deaminase production; Micrococcus luteus strain 4.43 produced indole acetic acid (IAA). Exopolysaccharide production was high in Bacillus methylotrophicus strain 5.18 while Bacillus sp. strain 5.2 did not show major properties for drought response. Inoculation of endophytic bacteria into plants, strain 3.13 and 4.43 increased height, shoot and root weight, root length, root diameter, root volume, root area and root surface of Jerusalem artichoke grown under water limitation, clearly shown in water supply at 1/3 of available water. These increases were caused by bacteria ACC deaminase and IAA production; moreover, strain 4.43 boosted leaf area and chlorophyll levels, leading to increased photosynthesis under drought at 60 days of planting. The harvest index was high in the treatment with strain 4.43 and 3.13 under 1/3 of available water, promoting tuber numbers and tuber weight. Inulin content was unchanged in the control between well-watered and drought conditions. In comparison, inulin levels were higher in the endophytic bacteria treatment under both conditions, although yields dipped under drought. Thus, the endophytic bacteria promoted in plant growth and yield under drought; they had outstanding function in the enhancement of inulin content under well-watered condition.

• KSBB Journal
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• v.9 no.5
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• pp.475-482
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• 1994

To find out the optimum conditions for the cell growth and the synthesis of PHB in A. eutrophus, the effects of culture conditions and extracellular by-products were investigated. Glucose and$>(NH_4)_2HP0_4$were optimum carbon and nitrogen sources, respectively for cell growth of A. eutrophus. PHB accumulation was stimulated by deficiency of nutrients such as $>NH_4^{3-}, P0_4^{3-}, and Mg^{2+}$ in the medium. $>NH_4^+$, deficiency was the most suitable for PHB accumulation and PHB accumulation ratio was reached 42% of dry cell weight. The specific growth rate was increased 1.5 times by addition yeast extract in the medium, and proteins and vitamins are supposed a main factor of that effect. The extracellular products such as ethanol and butanediol were excreted under anaerobic conditions. And ethanol was found to decrease the specific growth rate.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.08a
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• pp.55-67
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• 1999

A puc -deleted cell of Rhodobacter sphaeroides grows with a doubling time longer than 160 h under the light-limiting photoheterotrophic ( 3 Watts [W]/㎡) conditions due to an absence of the peripheral light-harvesting B800-850 complex. A spontaneous fast-growing mutant, R.sphaeroides SK101 was ioslate dto have∼40-h doubling at 3 Watts/㎡, while the growth of the mutant was not distinguished from its parental strain during both aerobic and light-saturating photoheterotrphic (10W/㎡) growth. The B875 complex of SK101 under the light-limiting conditions was elevated by 20 to 30% compared with that of the puc -deleted cell, reflecting parallel increase of bacteriochlorophyll and carotenoid contents of the mutant. The formation of B875 complex of SK101 under the anaerobic dark conditions with dimethylsulfoxide was the same as that of the puc-deleted cell. suggesting that the mutation of SK101 result in the altered control of B875 complex formation by light. When puc is restored in SK101 , it is not B875 complex but B800-850 complex which formation is elevated. The mutation of SK101 affected the bchF transcription most drastically to show two to tenfold increase during both aerobic and photoheterotrophic growth. The mutated phenotype of SK101 was complemented with pW2, which contains approximately 100-kb HNA of the photosynthetic gene clusters. The complementing DNA was narrowed down to a 1.1-kb DNA containing orfQ and pufKBA . The mutation of SK101 appeared to be exerted through the mutation of the orfQ gene encoding a putative bacteriochlorophyll -mobilizing protein.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.646-652
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• 2014

It is the primary aim of this paper to propose the empirical fatigue crack propagation model fit to describe a crack growth behavior of AZ31 magnesium alloys under the different specimen thickness conditions. The empirical models estimated are Paris-Erdogan model, Walker model, Forman model, and modified-Forman model. The parameters of each model are estimated by maximum likelihood method. The statistical crack growth data needed for an estimation of empirical models are obtained by fatigue crack propagation tests under the three cases of specimen thickness. It is found that the good empirical models fit to describe a crack growth behavior of AZ31 magnesium alloys under the different specimen thickness conditions are Paris-Erdogan model and Walker model. It is also verified that a fatigue crack growth rate exponent of a empirical model may be a material constant at the specimen thickness conditions of 4.75mm and 6.60mm.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1241-1255
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• 2021

This study was carried out to explore a non-chemical strategy for enhancing productivity by employing some antagonistic rhizobacteria. One hundred eighteen bacterial isolates were obtained from the rhizospheric zone of various crop fields of Gangwon-do, Korea, and screened for antifungal activity against Fusarium wilt (Fusarium oxysporum f. sp. lactucae) in lettuce crop under in vitro and in vivo conditions. In broth-based dual culture assay, fourteen bacterial isolates showed significant inhibition of mycelial growth of F. oxysporium f. sp. lactucae. All of the antagonistic isolates were further characterized for the antagonistic traits under in vitro conditions. The isolates were identified on the basis of biochemical characteristics and confirmed at their species level by 16S rRNA gene sequencing analysis. Arthrobacter sulfonivorans, Bacillus siamensis, Bacillus amyloliquefaciens, Pseudomonas proteolytica, four Paenibacillus peoriae strains, and Bacillus subtilis were identified from the biochemical characterization and 16S rRNA gene sequencing analysis. The isolates EN21 and EN23 showed significant decrease in disease severity on lettuce compared to infected control and other bacterial treatments under greenhouse conditions. Two bacterial isolates, EN4 and EN21, were evaluated to assess their disease reduction and growth promotion in lettuce in field conditions. The consortium of EN4 and EN21 showed significant enhancement of growth on lettuce by suppressing disease caused by F. oxysporum f. sp. lactucae respectively. This study clearly indicates that the promising isolates, EN4 (P. proteolytica) and EN21 (Bacillus siamensis), can be commercialized and used as biofertilizer and/or biopesticide for sustainable crop production.

• Korean Journal of Plant Tissue Culture
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• v.26 no.2
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• pp.103-107
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• 1999

The effects of MS salt strength, sucrose, and cultural conditions on bulblet formation and growth were investigated to optimize the conditions for micropropagating bulblets from in vitro bulb scales of Lilium Oriental Hybrid 'Casa Blanca'. There was no difference on bulblet formation in the range of 1/2~2 $\times$ strength of MS salt, but it was inhibited remarkably in 3 $\times$ strength of MS salt. The growth of regenerated bulblets was most stimulated on MS basal medium. Favorable bulblet formation and its growth from bulb scales were achieved when grown on the media with 1 : 2 or 1 : 3 in the ratio of NH$_4$^+ : NO$_3$^- , as well as on MS basal medium (NH$_4$^+ : NO$_3$^- = about l : 2). Therefore, MS basal medium was very suitable for bulblet formation and growth from bulb scales. Bulblet formation was inhibited but its growth was stimulated with increase sucrose concentration in the medium. The growth of regenerated bulblets was very effective on the media with 9~12% sucrose. Addition of activated charcoal (AC) to the medium inhibited bulblet formation from bulb scales, but enhanced the growth of regenerated bulblets. Especially, the medium containing 1 g/L AC was most effective on the growth of bulblets. No difference was found on bulblet formation and growth from bulb scales under light and dark conditions. In vitro micropropagation of L. Oriental Hybrid 'Casa Blanca' was supposed very reasonable to enhance the growth of the bulblets after forming of bulblets from in vitro bulb scales, and then, subculture the bulb scales from the grown bulblets on MS medium with 9% sucrose and 1 g/L AC.