• Journal of Microbiology and Biotechnology
• /
• v.4 no.2
• /
• pp.126-133
• /
• 1994

A Pseudomonas putida strain able to accumulate high amount of polyesters of medium-chain-length 3-hydroxyalkanoic acids ($PHA_{MCL)$) was isolated from soil in a landfill site using an enrichment technique. Culture condition of the isolated strain for polyester production in a one-step culture was optimized in a mineral-salts medium against pH and concentrations of ammonium sulfate, carbon source(e.g., octanoate), and phosphate. The optimal values for maximal cell growth and PHA accumulation were: pH; 7$\sim$8, $(NH_4)_2SO_4$; 8 mM, octanoate; 40 mM. The optimum temperature was in the range of $20\sim30^{\circ}C$, which was rather broader than in other bacteria. Cell growth was strongly inhibited by the phosphate limitation to less than 1 mM. An increase of phosphate concentration above 1 mM showed little effect on cell growth and polyester accumulation. When the strain was grown on octanoate under this optimized condition it produced 3.4 g dry biomass per liter and yielded 1.7 g PHA per liter amounting to 53 wt% of dry cells. The monomer units composing the polyester synthesized from octanoate were 3-hydroxyoctanoate (3HO), 3-hydroxycaproate (3HC), and 3-hydroxybutyrate (3HB) (85:13:2, mole ratio). Other low linear $C_3\simC_{10}$ monocarboxylic acids were also tested for polyester production.

• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.2 s.152
• /
• pp.130-138
• /
• 2007

A coupled variational equation for fluid-structure interaction (FSI) problems is derived from a steady state Navier-Stokes equation for incompressible Newtonian fluid and an equilibrium equation for geometrically nonlinear structures. For a fully coupled FSI formulation, between fluid and structures, a traction continuity condition is considered at interfaces where a no-slip condition is imposed. Under total Lagrange formulation in the structural domain, finite rotations are well described by using the second Piola-Kirchhoff stress and Green-Lagrange strain tensors. An adjoint shape design sensitivity analysis (DSA) method based on material derivative approach is applied to the FSI problem to develop a shape design optimization method. Demonstrating some numerical examples, the accuracy and efficiency of the developed DSA method is verified in comparison with finite difference sensitivity. Also, for the FSI problems, a shape design optimization is performed to obtain a maximal stiffness structure satisfying an allowable volume constraint.

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.3
• /
• pp.330-335
• /
• 1999

The goal of the study is to determine the most sensitive parameter to represent the degree of muscle force and fatigue. Various numerical parameters such as the first coefficient of Autoregressive (AR) Model, Root Mean Square (RMS), Zero Crossing Rate (ZCR), Mean Power Frequency (MPF), Median Frequency (MF) were tested in this study. Ten healthy male subjects participated in the experiment. They were asked to extend their trunk by using the right and left erector spinae muscles during a sustained isometric contraction for twenty seconds. The force levels were 15%, 30%, 45%, 60%, and 75% of Maximal Voluntary Contraction (MVC), and the order of trials was randomized. The results showed that RMS was the best parameter to measure the force level of the muscle, and that the first coefficient of AR model was relatively sensitive parameter for the fatigue measurement at less than 60% MVC condition. At the 75% MVC, however, both MPF and the first coefficient of AR Model showed the best performance in quantification of muscle fatigue. Therefore, the sensitivity of measurement can be improved by properly selecting the parameter based upon the level of force during a sustained isometric condition.

• Korean Journal of Pharmacognosy
• /
• v.49 no.1
• /
• pp.65-69
• /
• 2018

Torilin is a major sesquiterpene of Torilis japonica (Umbelliferae) fruits and known to be a melanogenesis inhibitor. Extraction conditions are important factor for the efficient preparation to save cost and time in economic aspects. For this reason, this study was conducted to optimize the extraction condition for maximal yield of torilin. For optimization, extraction factors such as extraction solvent, extraction temperature and sample/solvent ratio were tested and optimized for maximum yield of torilin using response surface methodology with Box-Behnken design (BBD). The optimal condition was obtained as a EtOAc concentration in MeOH of 31.8%, an extraction temperature at $30.3^{\circ}C$ and a sample/solvent ratio, 1000 mg/2 ml. The torilin yield under optimal conditions was found to be 9.9 mg/g dried samples, which were well-matched with the predicted value of 10.4 mg/g dried samples. These results will provide useful information about optimized extraction conditions for the development of torilin as cosmetic therapeutics to reduce skin hyperpigmentation.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.77.1-77.1
• /
• 2016

We investigate the properties and detection conditions for the planetary caustic perturbation of close-separation planets. To find the properties of the planetary caustic perturbation, we construct deviation maps by subtracting the single-lensing magnification of the lens star from the planetary lensing magnification for various lensing parameters. We find that each deviation area of the positive and negative perturbations disappears at the same normalized source radius according to a given deviation threshold regardless of mass ratio but disappears at a different normalized source radius according to the separation. We also estimate the upper limit of the normalized source radius to detect the planetary caustic perturbation. We find simple relations between the upper limit of the normalized source radius and the lensing parameters. From the relations, we obtain an analytic condition for the detection limit of the planet, and which show that we can sufficiently discover a planet with the mass of sub-Earth for typical microlensing events. Therefore, we expect to add the number of low-mass planets in the next-generation microlensing experiments and conclude that our detection condition of the planet can be used as a important criteria for maximal planet detections considering the source type and the photometric accuracy.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.2
• /
• pp.279-285
• /
• 2002

Phytase (myo-inositol hexakisphosphate phospho-hydrolase, EC 3.1.3.8) catalyzes the hydrolysis of phytate (myo-inositol hexakisphosphate) to release inorganic phosphate. A bacterial strain producing phytase was isolated from soil around a cattle shed. To identify the strain, cellular fatty acids profiles, the GC contents, a quinine-type analysis, and physiological test using an API 20NE kit were carried out. The strain was identified to be a genus of Pseudomonas sp. and named as Pseudomonas sp. YH40. The optimum culture condition for the maximum productivity of phytase by Pseudomonas sp. YH40 were attained in a culture medium composed of $1.0\%$ (w/v) glycerol, $2.0\%$ (w/v) peptone, and $0.2\%$ (w/v) $FeSO_4{\cdot}7H_2O$. Within the optimal medium condition, the production of phytase became highest after 10 h of incubation, and the maximal phytase production by Pseudomonas sp. YH40 was observed at $37^{\circ}C$ and pH 6.0.

• Bulletin of the Korean Mathematical Society
• /
• v.58 no.3
• /
• pp.659-668
• /
• 2021

Let R be a semiprime ring with maximal right ring of quotients Q_mr(R), and let n₁, n₂, …, n_k be k fixed positive integers. Suppose that R is (n₁+n₂+⋯+n_k)!-torsion free, and that f : 𝜌 → Q_mr(R) is an additive map, where 𝜌 is a nonzero right ideal of R. It is proved that if [[…[f(x), x^n₁], …], x^n_k] = 0 for all x ∈ 𝜌, then [f(x), x] = 0 for all x ∈ 𝜌. This gives the result of Beidar et al. [2] for semiprime rings. Moreover, it is also proved that if R is p-torsion, where p is a prime integer with p = Σ^k_i=1 n_i and if f : R → Q_mr(R) is an additive map satisfying [[…[f(x), x^n₁], …], x^n_k] = 0 for all x ∈ R, then [f(x), x] = 0 for all x ∈ R.

• Microbiology and Biotechnology Letters
• /
• v.28 no.5
• /
• pp.270-278
• /
• 2000

The study was performed to investgate the excellent microbial anticaries substance which is more effective that the chlorhexidine in the dental caries treatment. A typi-cal strain which produced the most excellent antimicrobial subatance was selected. and identified novel alkalophillic Bacillus alkalophilshaggy JY-827. For the maximal production of themicrobial antibiotic against Streptococcus mutans from B. alkalophilshaggy JY-827, the optimal culture condition was in the medium containing glucose 15g/ L, pepton 10g/L and $K_2$$HPO_4$ 2g/L the highest production of antibiotic against S.mutans was obtained at $25^{\circ}C$ and pH 11.0 for 5 days. The antibiotic from B. alkalophilshaggy JY-827 was purified by organic solvent extraction, silica gel and sephadex LH-20 column chromatograpies, and then crystallized with methanol. The crystallin compoma-tion of this antibiotic was as a curcular shape. The melting point and rm[$\alpha$]$D^{20}$ were 152-154$^{\circ}C$ and +55。, respec-tively. Based on Instumental analyses such as FT-IR, $^{1}$H-NMR $^{13}$ C-NMR and GC-mass, the antibiotic was identified as aminoglycoside. It was obtained as amorphous white power, and soluble in water power, and soluble in water, methanol but insoluble in ether, chroloform. This antibiotic inhibited the growth of S.mutans to about 3 day at the concentration of $2.5$\times$10^{-7}$ /M. It was stable at the alkalli condition but unstable within the acid condition. It was also stable up to $70^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.6
• /
• pp.647-656
• /
• 2008

In this paper, we present interference power distribution results when radio frequency identification(RFID) and ubiquitous sensor network(USN) systems share the $908.5{\sim}914MHz$ frequency bands. Average interference powers are obtained by simulation and statistical analysis, respectively. Simulation results are then verified by statistical analysis. According to the number of interferers and the diameter of the protection area, the cumulative density functions(CDFs) of interference power are simulated under the various conditions. From the simulation results, the probability that both USN and RFID systems meet the required maximal interference power levels is 95 % on condition that there are 1 low revered RFID reader and several USN nodes and that the minimum distance between a RFID reader and an USN node is greater than 1 m. Our results can be used as an basic research for coexistence analysis of RFID and USN systems in the $908.5{\sim}914MHz$ frequency bands.

• Journal of Food Hygiene and Safety
• /
• v.16 no.1
• /
• pp.33-36
• /
• 2001

V. parahaemolyticus possessed an extracellular alkaline protease activity during the stationary growth phase. Various factors such as initial pH of medium, incubation temperature and shaking rate were investigated far optimizing the production of alkaline protease from V. parahaemolyticus ATCC 17802. Maximal activity of the protease was obtained when the bacteria were grown in 2% skim milk medium in 0.1M tris/HCl buffer (pH 7.6). Maximal activity of the protease was obtained when the bacteria were growls at initial pH of 7.6, incubation temperature 37$^{\circ}C$ and shaking rate of 250 rpm.