• Mycobiology
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• 제33권2호
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• pp.90-96
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• 2005

Sixty two out of the sixty four species of fungal isolates tested could produce both $exo-{\beta}1,4-gluconase\;(C_1)$ and $endo-{\beta}1,4-gluconase\;(C_x)$ on pure cellulose and rice straw as carbon source in Czapek's medium. Fifty-eight and fifteen species were able to grow at $25^{\circ}C$ and at $45^{\circ}C$, respectively. Eleven species could grow at both $25^{\circ}C$ and $45^{\circ}C$ while, four species appeared only at $45^{\circ}C$. The most cellulolytic species at $25^{\circ}C$ was Trichoderma koningii producing 1.164 $C_1$ (mg glucose/1 ml culture filtrate/1 hr) and 2.690 $C_x$ on pure cellulose, and 0.889 $C_1$, and 1.810 $C_x$ on rice straw, respectively. At $45^{\circ}C$, the most active thermotolerant species were Aspergillus terreus, followed by A. fumigatus. Talaromyces thermophilus was the highest active thermophilic species followed by Malbranchea sulfurea. Most of these species were also active in fermentation of rice straw at 25 and $45^{\circ}C$ (P<0.05). The most active ones were T. koningii, A. ochraceus and A. terreus, which produced 201.5, 193.1 and 188.1 mg crude protein/g dry straw, respectively.

• 한국미생물·생명공학회지
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• 제47권3호
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• pp.381-389
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• 2019

Chlorella vulgaris was isolated from the Nile River, Qalubia Governorate, Egypt, for possible use in biodiesel production. BG-II nutrient growth media was used for isolation and laboratory growth. Identification was performed via 18S rRNA gene amplification, followed by sequencing. The alga was exposed to UV-C (254 nm) for 15, 30, and 45 s to improve dry weight accumulation and to increase the oil production. Daily measurements of dry weight ($g{\cdot}l^{-1}$) were performed; oil content and volumetric lipid productivity were also determined. UV-C exposure led to an increase in the volumetric lipid productivity by 27, 27.3, and $32.4mg{\cdot}l^{-1}{\cdot}d^{-1}$ with 15, 30, and 45 s, respectively, as compared with the control, which resulted in $18mg{\cdot}l^{-1}{\cdot}d^{-1}$. Of the examined mutants, the one with the highest productivity was re-irradiated by UV-C (254 nm) for 15, 30, 45, and 60 s. For 15 s of exposure time, the oil content increased to 34%, while it was 31% at 30 s; further, it decreased to 22% at 45 and 60 s exposures. The fatty acid methyl ester profile was 82.22% in the first mutant at 45 s, compared with the wild strain that contained a total of 66.01% of FAs. Furthermore, the highest levels of polyunsaturated fatty acid methyl ester were observed in the mutant exposed for 45 s, and it reached 11.41%, which reduced the cetane number to 71.3.

• Journal of Welding and Joining
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• 제23권6호
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• pp.72-76
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• 2005

Friction surfacing of STS304 consumable rod on S45C substrate was investigated by microstructural observation and mechanical tests. STS304 layer formed a strongly-bonded thick layer under a wide range of surfacing conditions. The highest coating eefficiency was obtained in the condition of 1000rpm-2.5mm/sec-2.5mm/sec. The hardness distribution showed the peak value in the boundary layer and as the consumable rotation speed increased, the boundary layer also hardness increasing. As the consumable rotation speed and the traveling speed increased, the coating efficiency tended to decrease. On the other hand, as the feeding speed increased, the coating efficiency appeared to be increased. The new Fe-Cr-Ni alloy layer is showed in the interface layer on $5\~15{\mu}m$ width. After friction surfacing, corrosion resistance of STS 304 surfacing layers were equaled to that of STS304 consumable rod.

• 한국해양공학회지
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• 제12권1호
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• pp.32-38
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• 1998

This paper is to investigate of microhardness, adhesive strength, tensile strength, and fatigue strength of ceramic sprayed steel. Rotary bending fatigue tests have been conducted at room temperature in air and 3% NaCl solution using specimens of carbon steel(S45C) with sprayed coating layers of Ni-4.5% Al(under coating) and $TiO_2$ (top coating). The microhardness has been improved at $800^{\circ}C$ heat treatment and 150mm spraying distance. Tensile strength of the sprayed steel is dependent on the substrate strength. The fatigue strength of the sprayed steel is larger than that of substrate due to blasting and constraint surface of plastic deformation effect. In low stress level, the corrosion fatigue strength of the sprayed steel were lower than that of fatigue strength in air by corrosion.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.29-36
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• 2007

The present study examined the mechanical properties of the friction welding of Ni-Cr-Mo to SM45C. Friction welding was conducted at welding conditions of 2,000 rpm, friction pressure of 100MPa, friction time of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 seconds, upset pressure of 150MPa, and upset time of 3.0 seconds. When the friction time was 1.6 seconds, the maximum tensile strength of the friction weld happened to be 1,020MPa, which is 120% of the base material's tensile strength(850MPa). At the same condition, the maximum shear strength was 438MPa, which is equivalent to 103% of the base material's shear strength(425MPa). At the same condition, the maximum vickers hardness was Hv490 at Ni-Cr-Mo nearby weld interface, which is higher Hv40 than condition of the friction time 0.8 seconds, and the maximum vickers hardness was Hv305 from weld interface of SM45C, which is higher Hv12 than condition of the friction time 0.8 seconds. The results of microstructure analysis show that the structures of two base materials have fined and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.

• Asian-Australasian Journal of Animal Sciences
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• 제11권1호
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• pp.35-42
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• 1998

Whole faba beans (WFB) were dry roasted at different temperatures (110, 130, $150^{\circ}C$) for 15, 30, 45 minutes to determine the optimal heating conditions of time and temperature to increase nutritional value. Ruminant degradation characteristics of crude protein (CP) of WFB were determined by the nylon bag incubation technique in dairy cows fed 60% hay and 40% concentrate. Measured characteristics of crude protein (CP) were soluble (washable) fraction (S), undegradable fraction (U), lag time (T0), potentially degradable fraction (D) and the rate of degradation (Kd) of insoluble but degradable fraction. Based on measured characteristics, percentage bypass crude protein (%BCP) and bypass crude protein (BCP in g/kg) were calculated. Degradability of CP was reduced by dry roasting (p < 0.01). S was reduced rapidly with increasing time and temperature, from 49.0% in the raw WFB (RWFB) to 26.3% in $150^{\circ}C/45$ min. D varied from 50.7% in RWFB to 73.7% in $150^{\circ}C/45^{\prime}$. U varied from 0% in $130^{\circ}C/45^{\prime}$, $150^{\circ}/30^{\prime}$ and $150^{\circ}/45^{\prime}$ to 0.66% in $110^{\circ}/45^{\prime}$ (0.24% for the RWFB). Lag time (T0) varied from 1.58 h in $130^{\circ}C/30^{\prime}$ to 2.40 h in $150^{\circ}C/45^{\prime}$ (1.87 h for RWFB). Kd varied from 24.2% in the $110^{\circ}C/30^{\prime}$ to 4.3% in $150^{\circ}C/45^{\prime}$ (21.4% for the RWFB). Kd was significantly reduced with time and temperature. All these effects resulted in increasing % BCP from 8.9% in the $110^{\circ}C/45^{\prime}$, 11.3% in the RWFB to 43.1% in the $150^{\circ}C/45$. Therefore BCP increased from 31.3 and 39.9 to 148.4 g/kg respectively. Both %BCP and BCP at $150^{\circ}C/45$ increased nearly 4 times over the raw faba beans. The effects of dry roasting temperature and time on %BCP and BCP seemed to be linear up to the highest values tested. Therefore no optimal dry roasting conditions of time and temperature could be determined at this stage. It was concluded that dry roasting was effective in shifting crude protein degradation from rumen to intestine to reduce unnecessary nitrogen (N) loss in the rumen. To determine the optimal treatment, the digestibility of each treatment should be measured in the next trial using mobile bags technique.

• 한국기계가공학회지
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• 제19권8호
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• pp.56-63
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• 2020

The heat transfer phenomenon in the vicinity of the irradiated region of a focused laser beam of a DMT process greatly affects both the deposition characteristics of powders on a substrate and the properties of the deposited region. The goal of this paper is to investigate the heat transfer characteristics of a single bead deposition of Inconel 718 powders on S45C structural steel using a laser-aided direct metal tooling (DMT) process. The finite element analysis (FEA) model with a Gaussian volumetric heat flux is developed to simulate a three-dimensional transient heat transfer phenomenon. The cross-section of the bead for the FEA is estimated with an equivalent area method using experimental results. Through the comparison of the results of the experiments and those of the analysis, the effective beam radius of the bottom region of the volumetric heat flux and the efficiency of the heat flux model for different powers and travel speeds of the laser are predicted. From the results of the FEA, the influence of the power and the travel speed of the laser on the creation of a steady-state heat transfer region and the formation of the heat-affected zone (HAZ) in the substrate are investigated.

• 대한수학회지
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• 제45권4호
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• pp.977-991
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• 2008

We characterize the boundedness and compactness of the weighted composition operator $uC_{\psi}$ from the general function space F(p, q, s) into the logarithmic Bloch space ${\beta}_L$ on the unit disk. Some necessary and sufficient conditions are given for which $uC_{\psi}$ is a bounded or a compact operator from F(p,q,s), $F_0$(p,q,s) into ${\beta}_L$, ${\beta}_L^0$ respectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.143-144
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.127-128
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• 2012