• Journal of Microbiology and Biotechnology
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• v.29 no.2
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• pp.283-291
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• 2019

Fermentation of food waste in the presence of different concentrations of salt ($Na^+$) and ammonia was conducted to investigate the interrelation of $Na^+$ and ammonia content in bio-hydrogen production. Analysis of the experimental results showed that peak hydrogen production differed according to the ammonia and $Na^+$ concentration. The peak hydrogen production levels achieved were (97.60, 91.94, and 49.31) ml/g COD at (291.41, 768.75, and 1,037.89) mg-N/L of ammonia and (600, 1,000, and 4,000) $mg-Na^+/L$ of salt concentration, respectively. At peak hydrogen production, the ammonia concentration increased along with increasing salt concentration in the medium. This means that for peak hydrogen production, the C/N ratio decreased with increasing salt content in the medium. The butyrate/acetate (B/A) ratio was higher in proportion to the bio-hydrogen production (r-square: 0.71, p-value: 0.0006). Different concentrations of $Na^+$ and ammonia in the medium also produced diverse microbial communities. Klebsiella sp., Enterobacter sp., and Clostridium sp. were predominant with high bio-hydrogen production, while Lactococcus sp. was found with low bio-hydrogen production.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.46-56
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• 2013

Laboratory scale experiments to remove benzene in solution by using the bio-carrier composed of dead biomass have been performed. The immobilized bio-carrier with dead Bacillus drentensis sp. and polysulfone was manufactured as the biosorbent. Batch sorption experiments were performed with bio-carriers having various quantities of biomass and then, their removal efficiencies and uptake capacities were calculated. From results of batch experiments, 98.0% of the initial benzene (1 mg/L) in 1 liter of solution was removed by using 40 g of immobilized bio-carrier containing 5% biomass within 1 hour and the biosorption reaction reached in equilibrium within 2 hours. Benzene removal efficiency slightly increased (99.0 to $99.4%{\pm}0.05$) as the temperature increased from 15 to $35^{\circ}C$, suggesting that the temperature rarely affects on the removal efficiency of the bio-carrier. The removal efficiency changed under the different initial benzene concentration in solution and benzene removal efficiency of the bio-carrier increased with the increase of the initial benzene concentration (0.001 to 10 mg/L). More than 99.0% of benzene was removed from solution when the initial benzene concentration ranged from 1 to 10 mg/L. From results of fitting process for batch experimental data to Langmuir and Freundlich isotherms, the removal isotherms of benzene were more well fitted to Freundlich model ($r^2$=0.9242) rather than Langmuir model ($r^2$=0.7453). From the column experiment, the benzene removal efficiency maintained over 99.0% until 420 pore volumes of benzene solution (initial benzene concentration: 1 mg/L) were injected in the column packed with bio-carriers, investigating that the immobilized carrier containing Bacillus drentensis sp. and polysulfone is the outstanding biosorbent to remove benzene in solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.354-355
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• 2008

The sensitivity and sensing margin of SOI(silicon on insulator) nano-wire BioFET(field effect transistor) were investigated by using back-gate bias. The channel conductance modulation was affected by doping concentration, channel length and channel width. In order to obtain high sensitivity and large sensing margin, low doping concentration, long channel and narrow width are required. We confirmed that the electrical sensing by back-gate bias is effective method for evaluation and optimization of bio-sensor.

• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.852-863
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• 2016

Wood-plastic composite (WPC) is a promising and sustainable material, and refers to a combination of wood and plastic along with some binding (adhesive) materials. In comparison to pure wood material, WPCs are in general have advantages of being cost effective, high durability, moisture resistance, and microbial resistance. The properties of WPCs come directly from the concentration of different components in composite; such as wood flour concentration directly affect mechanical and physical properties of WPCs. In this study, wood powder concentration in WPC was determined by Fourier transform near-infrared (FT-NIR) and Fourier transform infrared (FT-IR) spectroscopy. The reflectance spectra from WPC in both powdered and tableted form with five different concentrations of wood powder were collected and preprocessed to remove noise caused by several factors. To correlate the collected spectra with wood powder concentration, multivariate calibration method of partial least squares (PLS) was applied. During validation with an independent set of samples, good correlations with reference values were demonstrated for both FT-NIR and FT-IR data sets. In addition, high coefficient of determination (${R^2}_p$) and lower standard error of prediction (SEP) was yielded for tableted WPC than powdered WPC. The combination of FT-NIR and FT-IR spectral region was also studied. The results presented here showed that the use of both zones improved the determination accuracy for powdered WPC; however, no improvement in prediction result was achieved for tableted WPCs. The results obtained suggest that these spectroscopic techniques are a useful tool for fast and nondestructive determination of wood concentration in WPCs and have potential to replace conventional methods.

• Journal of Power System Engineering
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• v.16 no.4
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• pp.5-11
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• 2012

There were some papers for diesel engine performance tests using BDF, but few article deals with the temperature and soot concentration of Bio diesel flame. Since the flame temperature of diesel engines is so high and change rapidly, an optical method for measurement of flame temperature is known as the most effective one. The two-color method regarding the visible wavelength radiation for the soot particles in flame was applied on Bio diesel flame in order to measure flame temperature and soot concentration in a diesel engine. Photo detecting device was newly designed and employed TSL250R, photo-diode, to pick-up the light information emitted from the combustion flame. As a result, real flame temperature T, as a flame brightness temperature, through Ta1, Ta2, were obtained and finally the characteristics of KL value as a soot concentration reveal the difference of combustion information between diesel fuel, blending oil and Bio diesel fuel oil.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1962-1966
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• 2012

Boehmite sols have been prepared by crystallization of amorphous aluminum hydroxide gel obtained by hydrolysis and peptization of aluminum using acetic acid. The size of the boehmite crystallites could be controlled by Al molar concentration in amorphous gel by means of controlling grain growth at nucleation stage. The size of boehmite increases as a function of Al molar concentration. With increasing boehmite crystallite size, the $d_{(020)}$ spacing and the specific surface area decreases, whereas the pore volume increases along with pore size. Especially, the pore size of the boehmite sol particles is comparable to the crystallite size along the b axis, suggesting that the fibril thickness along the b axis among the crystallite dimensions of the boehmite contributes to the pore size. Therefore, the physical properties of boehmite sols can be determined by the crystallite size controlled as a function of initial Al concentration.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.201-204
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• 2012

Combustion characteristics of boiler fuels made of bio-oil and light-oil were experimentally investigated. Bio-oil was obtained by fast pyrolysis of woody biomass. Emulsion fuel made by mixing bio-oil (up to 30wt%) with light-oil and surfactant was completely burnt, resulting in the formation of combusted gas containing CO concentration less than 10ppm. Simple mixtures of bio-oil and light-oil with separate delivery lines also gave nice combustion characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.87-87
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• 2013

Sample concentration and purification processes are essential in the bio-analytical and pharmaceutical fields because most bio samples or media are extremely sophisticated. To concentrate and purify specific substances, passive membrane type filters have been utilized, which is driven by size or charge differences between target and others. The traditional and representative method to identify nucleic acid sequences in the complex biosample is gel electrophoresis, which has been worked by size and net charge of molecules. The adsorption phenomena have been also utilized to concentrate and purify biomolecules. This adsorption of biomolecule can be controlled under specific salts and surfaces as well as surface area. To utilize the differences of physical properties of molecules or bio-targets such as virus, bacteria, and cells, the nanotechnologies can be introduced in target concentration, purification, and isolation processes. In here, I'd like to briefly survey typical examples of nanobiotechnologies which are introduced in sample treatment. Also I specifically demonstrate two different simple techniques to concentrate and detect bacteria from the samples using multifunctional silica nanotube (SNT).

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.312-320
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• 2011

In order to estimate a better methodological factor to understand phytoplankton ecology between abundance and bio-volume of phytoplankton, each 1,160 phytoplankton data, including abundance, classification and chlorophyll $a$ concentration were collected in Korean coastal waters of Incheon (Yellow sea), Tongyeong (South sea), and Ulsan (East sea). Based on these data, phytoplankton bio-volume can be calculated through a geometric model. The correlation coefficient between abundance and chlorophyll $a$ concentration was higher than the coefficient between biovolume and chlorophyll $a$ concentration, because a small size phytoplankton has relatively dense chlorophyll contents compared with the proportion of chlorophyll in a large size phytoplankton. Thus, the interpretation using abundance to understand phytoplankton ecology in Korean coastal waters may be more effective than that using bio-volume.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.354-365
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• 1993

A novel control method with automatic tuning of PID controller parameters has been developed for efficient regulation of dissolved oxygen concentration in fed-batch fermentations of Escherichia coli. Agitation speed and oxygen partial pressure in the inlet gas stream were chosen to be the manipulated variables. A heuristic reasoning allowed improved tuning decisions from the supervision of control performance indices and it coule obviate the needs for process assumptions or disturbance patterns. The control input consisted of feedback and feedforword parts. The feedback part was determined by PID control and the feedforward part is determined from the feed rate. The proportional gain was updated on-line by a set of heuristics rules based on the supervision of three performance indices. These indices were output error covariance, the average value of output error, and input covariance, which were calculated on-line using a moving window. The integral and derivative time constants were determined from the period of output response. The specific growth rate was maintained at a low level to avoid acetic acid accumulation and thus to achieve a high cell density. The specific growthe rate was estimated from the carbon dioxide evolution rate. In fed-batch fermentation, the simutaneous control of dissolved oxygen concentration (at 0.2; fraction of saturated value) and specific growth rate (at 0.25$hr^{-1}$) was satisfactory for the entire culture period in spite of the changes in the feed rate and the switching of control input.