• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.446-452
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• 2003

Some new nanohybrid materials have been synthesized by intercalating the oxotitanium(IV) meso-tetrakis(4- sulfonatophenyl) porphyrin$(O=Ti^{(IV)} TSPP)$ into the Zn/Al layered double hydroxides (LDHs), and their structures and photophysical properties have been investigated by various laser spectroscopic techniques. According to the XRD pattern of the synthesized nanohybrid materials, the macrocycle plane of $O=Ti^{(IV)}$ TSPP are grafted perpendicular to the LDH layers. The $O=Ti^{(IV)}$ TSPP-intercalated LDH exhibits band broadening of the absorption spectrum and a blue shift of Q-band as compared to that observed in solution. Resonance Raman spectral measurements demonstrate that the positively charged LDHs give rise to a slight decrease of the electronic density of the porphyrin ring accompanying a small change of the electronic distribution of the $O=Ti^{(IV)}$ TSPP. Consequently the LDH environment affects the energies of the two highest occupied molecular orbitals (HOMOs) of the $O=Ti^{(IV)}$) TSPP, $a_{1u}$ and $a_{2u}$, producing a mixed orbital character. Being consistent with these electronic structural changes of $O=Ti^{(IV)}$ TSPP in LDH, both the fluorescence spectral change and the fsdiffuse reflectance transient measurements imply that the photoexcitation of the $O=Ti^{(IV)}$ TSPP intercalated into LDH undergoes fast relaxation to the O=Ti(IV) $TSPP^+-LDH^- $charge transfer (CT) state within a few picoseconds, followed by a photoinduced electron transfer between the O=Ti(IV) TSPP and LDHs with a rate constant greater than %1×10^{10}S^{-1}$. No evidence is found for back electron transfer. In conclusion, the $O=Ti^{(IV)}$ TSPP intercalated LDH seems to be a possible candidate for an artificial reaction center for an efficient solar energy conversion system.

• Clean Technology
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• v.19 no.2
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• pp.156-164
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• 2013

In this study, we analyzed the operational characteristics of a 0.25 MW methanation pilot plant. Isothermal reactor controled the heat released from methanation reaction by saturated water in shell side. Methanation process consisting of isothermal reactor and adiabatic reactor had advantages with no recycle compressor and more less reactors compared with methanation process with only adiabatic reactors. In case that $H_2$/CO ratio of syngas was under 3, carbon deposition occurred on catalyst in tube side of isothermal reactor and the pressure of reactors increased. In case that $H_2$/CO ratio was maintained around 3, no carbon deposition on catalyst in tube side of isothermal reactor was found by monitoring the differential pressure of reactors and by measuring the differential pressure of several of tubes filled with catalyst before and after operating. It was shown that CO conversion and $CH_4$selectivity were over 99, 97%, respectively, and the maximum $CH_4$productivity was $695ml/h{\cdot}g-cat$.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.377-385
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• 2017

The solar cell need the characteristic interpreting because the solar cell changes greatly according to the isolation, temperature and load in the photovoltaic development. Moreover, to get many energy in photovoltaic development need the position tracking of the sun according to the environment change. Also, The solar cells should be operated at the maximum power point. In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control. The result was less then 5% when compared the catalogue of solar cell module and the simulation through a mathematics modelling. The boost rate of boost converter was similar to 167 % with the simulation.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.9
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• pp.1285-1291
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• 2017

Objective: A trial was conducted from 11 to 42 d post-hatch to investigate the effectiveness of the supplementation of a multiple-enzyme preparation (Natuzyme Plus) in a wheat-based diet on digesta viscosity, pH and microbial population, villus morphology, feed passage time, nutrient retention, carcass characteristics, blood lipid parameters and growth performance of broiler chickens. Methods: Three hundreds 10-d-old male Ross 308 chicks were allocated to three diets with five replicates of 20 birds per replicate. Dietary treatments were i) a wheat-based diet (W), ii) W+Natuzyme Plus (WN; 500 mg/kg of the diet), and iii) a corn-based diet (C). Results: Birds fed on the C diet had higher average daily gain (ADG, p<0.01), villus height (VH, p<0.01), total tract apparent retention (TTAR) of nitrogen (NT, p<0.01) and ether extract (EE, p<0.01), nitrogen-corrected apparent metabolizable energy ($AME_n$, p<0.05), relative weight (RW, % of body weight) of carcass (p<0.05), blood concentration of triglyceride (TG, on d 40 [p<0.01]), total cholesterol (TC, on d 22 [p<0.05]) and low density lipoprotein (LDL, on d 22 [p<0.01] and 40 [p<0.05]), and also lower feed conversion ratio (FCR, p<0.01), digesta viscosity (p<0.01), count of coliforms (p<0.01) and Escherichia coli (p<0.01) and epithelium thickness (ET, p<0.05) than those fed on the W diet. ADG, FCR, VH, ET, TTAR of NT and EE, RW of carcass, blood concentration of TG (on d 40), TC (on d 22) and LDL (on d 22 and 40) values of the WN diet did not show a significant (p>0.05) difference compared to those of the C diet. Compared to those of the W diet, the WN diet showed the higher count of Lactobacilli and lower count of coliforms (p<0.01) and digesta viscosity (p<0.01). Conclusion: In general, the results of this study showed that Natuzyme Plus supplementation in a wheat-based diet can be appropriate to achieve a comparable growth performance in broiler chickens to those given the C diet probably through improving digesta viscosity, VH, ET, TTAR of NT and EE, $AME_n$, count of Lactobacilli and coliforms.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.720-726
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• 2014

PEM fuel cell vehicles have been getting much attraction due to a sort of highly clean and effective transportation. The onboard fuel processor, however, is inevitably required to supply the hydrogen by conversion from some fuels since there are not enough available hydrogen stations nearby. A lot of studies have been focused on analyses of ATR reactor under the assumption of thermo-neutral condition and those of the optimized process for the minimization of energy consumption using thermal efficiency as an objective function, which doesn't guarantee the maximum hydrogen production. In this study, the analysis of optimization for 100 kW PEMFC onboard fuel processor was conducted targeting various fuels such as gasoline, LPG, diesel using newly defined hydrogen efficiency and keeping simply synthesized heat exchanger network regardless of external utilities leading to compactness and integration. Optimal result of gasoline case shows 9.43% reduction compared to previous study, which shows the newly defined objective function leads to better performance than thermal efficiency in terms of hydrogen production. The sensitivity analysis was also done for hydrogen efficiency, heat recovery of each heat exchanger, and the cost of each fuel. Finally, LPG was estimated as the most economical fuel in Korean market.

• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.306-309
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• 2007

PXLM(Phosphor based x-ray light modulator) has a combined structure by phosphor, photoconductor, and liquid crystal and it can realize x-ray image of high resolution in clinical diagnosis area. In this study, we fabricated a photoconductor and investigated electrical and optical properties to confirm application possibility of radiator detector of PXLM structure. As photoconductor, amorphous selenium(a-Se), which is used most in DR(Digital radiography) of direct conversion method, was used and for formation of thin film, it was formed as $20{\mu}m-thick$ by using thermal vacuum evaporation system. For a produced a-Se film, through XRD(X-ray diffraction) and SEM(Scanning electron microscope), we investigated that amorphous structure was uniformly established and through optical measurement, for visible light of 40 $0\sim630nm$, it had absorption efficiency of 95 % and more. After fabricated a-Se film on the top of ITP substrate, hybrid structure was manufactured through forming $Gd_2O_3:Eu$ phosphor of $270{\mu}m-thick$ on the bottom of the substrate. As the result to confirm electrical property of the manufactured hybrid structure, in the case of appling $10V/{\mu}m$, leakage current of $2.5nA/cm^2$ and x-ray sensitivity of $7.31nC/cm^2/mR$ were investigated. Finally, we manufactured PXLM structure combined with hybrid structure and liquid crystal cell of TN(Twisted nematic) mode and then, investigated T-V(Transmission vs. voltage) curve of external light source for induced x-ray energy. PXLM structure showed a similar optical response with T-V curve that common TN mode liquid crystal cell showed according to electric field increase and in appling $50\sim100V$, it showed linear transmission efficiency of $12\sim18%$. This result suggested an application possibility of PXLM structure as radiation detector.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.239-246
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• 2015

The present study was conducted to evaluate the effect of the dietary supplementation of Bacillus amyloliquefaciens-based direct-fed microbial (DFM) on growth performance, nutrient utilization, intestinal morphology and cecal microflora in broiler chickens. A total of two hundred and eighty eight 1-d-old Arbor Acres male broilers were randomly allocated to one of four experimental treatments in a completely randomized design. Each treatment was fed to eight replicate cages, with nine birds per cage. Dietary treatments were composed of an antibiotic-free basal diet (control), and the basal diet supplemented with either 15 mg/kg of virginiamycin as antibiotic growth promoter (AGP), 30 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 30) or 60 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 60). Experimental diets were fed in two phases: starter (d 1 to 21) and finisher (d 22 to 42). Growth performance, nutrient utilization, morphological parameters of the small intestine and cecal microbial populations were measured at the end of the starter (d 21) and finisher (d 42) phases. During the starter phase, DFM and virginiamycin supplementation improved the feed conversion ratio (FCR; p<0.01) compared with the control group. For the finisher phase and the overall experiment (d 1 to 42) broilers fed diets with the DFM had better body weight gain (BWG) and FCR than that of control (p<0.05). Supplementation of virginiamycin and DFM significantly increased the total tract apparent digestibility of crude protein (CP), dry matter (DM) and gross energy during both starter and finisher phases (p<0.05) compared with the control group. On d 21, villus height, crypt depth and villus height to crypt depth ratio of duodenum, jejunum, and ileum were significantly increased for the birds fed with the DFM diets as compared with the control group (p<0.05). The DFM 30, DFM 60, and AGP groups decreased the Escherichia coli population in cecum at d 21 and d 42 compared with control group (p<0.01). In addition, the population of Lactobacillus was increased in DFM 30 and DFM 60 groups as compared with control and AGP groups (p<0.01). It can be concluded that Bacillus amyloliquefaciens-based DFM could be an alternative to the use of AGPs in broilers diets based on plant protein.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.5
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• pp.788-801
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• 2020

Objective: This study was conducted to evaluate the effects of diets containing different wet rice distillers' by-product (RDP) levels on growth performance, nutrient digestibility, blood profiles and gut microbiome of weaned piglets. Methods: A total of 48 weaned castrated male crossbred pigs, initial body weight 7.54±0.97 kg, and age about 4 wks, were used in this experiment. The piglets were randomly allocated into three iso-nitrogenous diet groups that were fed either a control diet, a diet with 15% RDP, or a diet with 30% RDP for a total of 35 days. Chromium oxide was used for apparent digestibility measurements. On d 14 and d 35, half of the piglets were randomly selected for hemato-biochemical and gut microbiota evaluations. Results: Increasing inclusion levels of RDP tended to linearly increase (p≤0.07) average daily gain on d 14 and d 35, and decreased (p = 0.08) feed conversion ratio on d 35. Empty stomach weight increased (p = 0.03) on d 35 while digestibility of diet components decreased. Serum globulin concentration decreased on d 14 (p = 0.003) and red blood cell count tended to decrease (p = 0.06) on d 35, parallel to increase RDP levels. Gene amplicon profiling of 16S rRNA revealed that the colonic microbiota composition of weaned pigs changed by inclusion of RDP over the period. On d 14, decreased proportions of Lachnospiraceae_ge, Ruminococcaceae_ge, Ruminococcaceae_UCG-005, and Bacteroidales_ge, and increased proportions of Prevotellaceae_ge, Prevotella_2, and Prevotella_9 were found with inclusion of RDP, whereas opposite effect was found on d 35. Additionally, the proportion of Lachnospiraceae_ge, Ruminococcaceae_ge, Ruminococcaceae_UCG-005, and Bacteroidales_ge in RDP diets decreased over periods in control diet but increased largely in diet with 30% RDP. Conclusion: These results indicate that RDP in a favorable way modulate gastrointestinal microbiota composition and improve piglet performance despite a negative impact on digestibility of lipids and gross energy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.13-20
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• 2008

This paper describes the design of low power 12bit Digital-to-Analog Converter(D/A Converter) using Pseudo-Segmentation method which shows the conversion rate of 80MHz and the power supply of 1.8V with 0.18um CMOS n-well 1-poly 6-metal process for advanced wireless communication system. Pseudo-segmentation method used in binary decoder consists of simple parallel buffer is employed for low power because of simpler configuration than that of thermometer decoder. Also, using deglitch circuit and swing reduced drivel reduces a switching noise. The measurement results of the proposed low power 12bit 80MHz CMOS D/A Converter shows SFDR is 66.01dBc at sampling frequency 80MHz, input frequency 1MHz and ENOB is 10.67bit. Integral nonlinearity(INL) / Differential nonlinearity(DNL) have been measured ${\pm}1.6LSB/{\pm}1.2LSB$. Glich energy is measured $49pV{\cdot}s$. Power dissipation is 46.8mW at 80MHz(Maximum sampling frequency) at a 1.8V power supply.

• KSBB Journal
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• v.25 no.4
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• pp.337-343
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• 2010

It has been well known that organic solvents like t-butanol and n-hexane can protect lipases from the inhibition by short-chain alcohols in the enzymatic transesterification. However, use of the organic solvents should be minimized considering their negative effects on environment and human health. Therefore, use of the greener solvents has been pursued in various are as including the enzymatic biotranformation. In this study, the liquid carbon dioxide ($LCO_2$) was employed as an alternative media for the enzymatic transesterification of canola oil. The conversion in the $LCO_2$ was comparable with those in organic solvents and the supercritical carbon dioxide, and under optimum conditions, the value reached 99.7%. It is expected that this method can provide a new type of biodiesel production process with higher energy efficiency and lower environmental impact.