• Microbiology and Biotechnology Letters
• /
• v.26 no.2
• /
• pp.167-172
• /
• 1998

In batch cultures of Brevibacterium ketoglutamicum for the L-ornithine production in which the pH and dissolved oxygen concentration were regulated constant, the profiles of redox potential were observed in parallel with the profiles of state variables such as cell, glucose, and ornithine concentrations. It was found that the redox potential had a close relationship with cell concentration and was also affected by ornithine concentration. The effects of ornithine and glucose on redox potential were examined in a separate series of experiments. Based on the experimental results, a correlation of redox potential to glucose, cell and ornithine concentrations has been proposed. The proposed correlation can be used for on-line estimation of ornithine concentration from on-line data of redox potential, glucose concentration, and cell concentration.

• Journal of computational fluids engineering
• /
• v.3 no.1
• /
• pp.63-72
• /
• 1998

The numerical simulations of flowfield and pollutant dispersion over two-dimensional hills of various shapes are described. The Reynolds-averaged Wavier-Stokes equations and concentration diffusion equation based on the gradient diffusion theory have been applied to the atmospheric shear flow over the bell-shaped hills which are basic components of the complex terrain. The flow characteristics such as velocity profiles of the geophysical boundary layer, speed-up phenomena, mean pollutant concentration profiles are compared with experimental data to validate the present numerical procedure and it has been found that the present numerical results agree well with experiments and other numerical data. It has been also found that the distributions of ground level concentration are strongly influenced by the source location and height.

• ETRI Journal
• /
• v.11 no.4
• /
• pp.75-83
• /
• 1989

The diffusion mechanism of Si in GaAs was investigated using different diffusion sources based on the Si-Ga-As ternary phase equilibria. The Si profiles are measured with secondary ion mass spectrometry and differ significantly for sources taken from the different phase fields in the ternary phase diagram. Neutral As vacancy diffusion is proposed for acceptor Si diffusion anneals using a Ga - Si - GaAs source. Donor Si diffusion using As - rich sources and a Si -GaAs tie line source shows concentration dependent diffusion behavior. Concentration dependent diffusion coefficients of donor Si for As - rich source diffusion were found to be related to net ionized donor concentration and showed three regimes of different behavior: saturation regime, intermediate regime,and intrinsic regime. Ga vacancies are proposed to be responsible for donor Si diffusionin GaAs: $Si_Ga^+V_Ga^-$ (donor Si -acceptor Gavacancy) complex for the extrinsic regime and neutral $V_G$a, for the intrinsic regime.The Si - GaAs tie line source resulted in two branch profiles, intermediate between the As - rich and the Ga - rich source diffusion cases.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.484-490
• /
• 2003

The amount of the tritium released from Wolsong units during the WTRF operation is predicted. The profiles of tritium concentration in moderators and PHTs as variation of WTRF service allotment for each Wolsong unit are calculated, and the tritium releases are obtained from these tritium concentration profiles. The tritium concentration in moderator will be decreased down under 10 Ci/kg in 2013 and the yearly tritium release will be reduced below 25% of WTRF start year.

• Journal of Nutrition and Health
• /
• v.33 no.6
• /
• pp.597-612
• /
• 2000

The aim of this study was to evaluate the effects of soyoligosaccharides on intestinal microflora transit time lipid profiles and immune responses. Forty-eight male rats of Sprague-Dawley strain were divided into six groups(SYS: soybean oil-sucrose SYO: soybean oil-oligo SES; esame oil-sucrose SEO:sesame oil-oligo BFS : beef tallow-sucrose BFO : beef tallow-oligo) soyoligo-groups(SYO, SEO, BEO) were fed the diet containing 5% soyoligosaccharides but control groups not fed them and all groups were fed 20% fats for 4 weeks. The number of fecal bifidobacteria tended to increase after soyoligosaccharides feeding. The significant increase was found in SEO group compared to SES in that of fecal bifidobacteria,. Stool wet weight dry fecal weight and stool water content were increased significantly in soyoligo-group(SYO, SEO, BFO) compared to control groups(SYS, SES, BFS) and gastrointestinal transit time(TT) tended to increase. Soyoligosaccharides lowered plasma cholesterol in SEO group significantly more than did other groups. soyoligo-groups(SYO, SEO, BFO) tended to decrease liver triglycerides compared to control groups. Plasma IgG concentration increased in beef tallow groups(BFS, BFO) than that in other dietary fat groups. Soyoligosaccharides and kinds of fats had effects on plasma C3 concentration and mitogenesis of the spleen cells. Soyoligosaccharides had no effects on plasma leptin and insulin concentration but kinds of fats did so that sesame groups were decreased significantly in plasma leptin concentration but increased significantly in plasma insulin concentration compared to other dietary fat groups. In conclusion dietary soyoligosaccharides changed the composition of the intestinal microflora beneficially with sesame oil and partially had effect on plasma and liver lipid profiles .(Korean J Nutrition 33(6) : 597∼612, 2000)

• Journal of Welding and Joining
• /
• v.22 no.4
• /
• pp.59-64
• /
• 2004

The purpose of this study is to investigate the influence of weld bead profiles on stress concentration factors of double V groove butt-welded joints. The influence of three parameters such as toe radii, flank angles and bead heights on the stress concentration factors is studied by finite element analysis. It is shown that the three parameters have similar effects on the stress concentration factors. Finally a formula to estimate the stress concentration factors considering the three parameters and others is proposed and estimated results are compared with the results obtained by finite element analysis.

• Environmental Engineering Research
• /
• v.12 no.2
• /
• pp.55-63
• /
• 2007

PCDD/Fs monitoring was carried out to estimate the contamination level in soil samples taken in the vicinity of the various incinerators throughout South Korea from July 2003 to December 2004. The levels ranged from N.D. to 130.39 pg I-TEQ/g (d.w.) with an average concentration of 11.38 pg I-TEQ/g (d.w.). The level of PCDD/Fs in this study is similar to that of other countries. Overall, the highest mean concentration in the soil was found at 250 m from the stack. In addition, the flue gases were analyzed in order to obtain the congener profiles of the PCDD/Fs emitted from the incinerators. The concentration of I-TEQ in the flue gas ranged from 0.33 to 21.5 ng TEQ/$Sm^3$. These levels were much lower than the concentration stipulated in the Korean emission criterion(40 ng TEQ/$Sm^3$ until 2005). The comparison of the congener patterns using cluster analysis showed that the incinerators and PCP are sources of PCDD/Fs in the soil samples according to the sampling point, but the possibility of unidentified combustion sources and vehicles exists in the case of complex industrial regions.

• Nuclear Engineering and Technology
• /
• v.51 no.8
• /
• pp.2013-2017
• /
• 2019

The radon concentrations in soil air were measured before and after a rainfall. ²²⁶Ra concentration, porosity, moisture content and temperature in soil were measured at Kyungpook National University in Daegu. As the results of measurement and analysis, the arithmetic mean of measured ²²²Rn concentration increased from 12100 ± 500 Bq/㎥ to 16200 ± 600 Bq/㎥ after the rainfall. And the measured ²²⁶Ra concentration was 61.4 ± 5.7 Bq/kg and the measured porosity was 0.5 in soil. The estimated values of ²²⁶Ra concentration and porosity using diffusion model of ²²²Rn in soil were 60.3 Bq/kg and 0.509, respectively. The estimated values were similar to the measured values. ²²²Rn concentration in soil increased with depth and moisture content. The estimations were obtained through fitting based on the diffusion model of ²²²Rn using the measurement values. The measured depth profiles of ²²²Rn were similar to the calculated depth profiles of ²²²Rn in soil. We hope that the results of this study will be useful for environmental radiation analysis.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.18 no.1
• /
• pp.7-19
• /
• 1981

Anodization method is utilized in order to measure diffusion profiles of boron and arsenic in silicon. The solution used for silicon anodization is Ethylene glycol +KNO3(0.04N), The thickness of silicon which is consumed by a single 200V anodization is 460$\pm$40A regardless of wafer type. The profiles of boron and arsenic in silicon after predeposition process are investigated. The diffusion coefficients of both dopants depending on impurity concentration are extrated from these profiles. The base pull-in effect has been observed in prototype npn transistors with arsenic doped emitter.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.7
• /
• pp.1049-1058
• /
• 1990

Mathematical modeling equations of a parallel plate type reactor were obtained in the PECVD process in preparing hydrogenated amorphous silicon. Velocity profiles, temperature profiles and concentration profiles in the reactor were calculated from the model. The theoretical approach was attempted to obtain the deposition rate and film uniformity at different operating conditions by calculating RF discharge parameters and establishing the reaction mechanisms of a-Si:H thin film. The modelling equations are solved by a finite difference method with control volume balance. The mean electrom energy in discharge was applied to model simulation parameter. The magnitudes of the predicted deposition rate are in good aggrement with those of experiment. The results of computer simulation shows that uniform deposition profiles can.