• Applied Chemistry for Engineering
• /
• v.26 no.2
• /
• pp.205-209
• /
• 2015

CCU (Carbon Capture & Utilization) has a potential technology for the reduction and usage of carbon dioxide which is greenhouse gas emitting from a fossil fuel buring. To decompose the carbon dioxide, a three phase gliding arc plasma-catalytic reactor was designed and manufactured. Experiments of carbon dioxide reduction was performed by varying the gas flow rate with feeding the $CO_2$ only as well as the input power, the catalyst type and steam supply with respect to the injection of the mixture of $CO_2$ and $CH_4$. The $CO_2$ decomposition rate was 7.9% and the energy efficiency was $0.0013L/min{\cdot}W$ at a $CO_2$ flow rate of 12 L/min only. Carbon monoxide and oxygen was generated in accordance with the destruction of carbon dioxide. When the injection ratio of $CH_4/CO_2$ reached 1.29, the $CO_2$ destruction and $CH_4$ conversion rates were 37.8% and 56.6% respectively at a power supply of 0.76 kW. During the installation of $NiO/Al_2O_3$ catalyst bed, the $CO_2$ destruction and $CH_4$ conversion rates were 11.5% and 9.9% respectively. The steam supply parameter do not have any significant effects on the carbon dioxide decomposition.

• Journal of Energy Engineering
• /
• v.12 no.1
• /
• pp.58-64
• /
• 2003

With the 1 ton/day-class entrained-bed gasification system, heavy residual oil from local refinery was gasified at the operating conditions of 1,000~1,20$0^{\circ}C$ and 3 $kg_f$/$\textrm{cm}^2$ in order to determine the variation of syngas composition, carbon conversion, and cold gas efficiency. Produced syngas consists of mainly CO, H$_2$, $CO_2$, and the methane concentrations. Results yielded a maximum syngas composition of 45% H$_2$ and 26%, CO at the 31 kg/hr feeding condition. The maximum carbon conversion and cold gas efficiency were 87% and 68%, respectively at the feeding conditions of 20 kg/hr and oxygen/feed ratio of 1.2. When oxygen feeding amount that is one of the most important operating parameter in gasification was increased, concentration of hydrogen in the syngas is greatly increased comparing to the concentration of CO and $CO_2$. The temperature exhibited about 11$0^{\circ}C$ raise while oxygen/feed ratio changed from 0.6 to 1.2. Methane concentration showed enhanced dropping rate with increase in gasifier temperature and the useful relationship between the gasifier temperature and methane concentration existed such that it can be employed as an indirect measure of inside gasifier temperature.

• Journal of the Korean Magnetics Society
• /
• v.18 no.1
• /
• pp.19-23
• /
• 2008

The mixed ferrite $V_xFe_{3-x}O_4$(x=0.0, 0.15, 0.5, 1.0) thin films were prepared by sol-gel method. Their crystallographic and magnetic hyperfine properties have been studied using X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and conversion electron $M\"{o}ssbauer$ spectroscopy(CEMS). The crystal structure is found to be cubic spinel throughout the series($x{\leq}1.0$), and the lattice parameter $a_0$ increases linearly with increasing V content. XRD, XSP and CEMS indicate that $V^{3+}$ substitution for $Fe^{3+}$ in B-site is superior to $V^{2+}$ substitution for $Fe^{2+}$ in B-site. It is noticeable that both quadrupole shift and hyperfine field decreases with increasing V composition, suggesting the change of local symmetry and accompanying line-broadening. The line-broadening on CEMS spectra can be explained by the distribution of magnetic hyperfine fields.

• Korean Chemical Engineering Research
• /
• v.60 no.2
• /
• pp.193-201
• /
• 2022

5-HMF(5-Hydroxymethylfurfural) and LA(levulinic acid) derived from biomass are green platform chemicals, which have a wide of potential applications as biofules and biochemicals. In this study, the kinetics of LA formation from glucose decomposition with various concentration of sulfuric acid at different temperature was investigated. The experiments were performed in a broad temperature (140-200 ℃), using H₂SO₄ (1-3 wt%) as the catalyst. Glucose solution was made by dissolving 1 g of glucose in 10 ml of H₂SO₄ solution. The reactions rates increased with temperature and the activation energy showed a similar tendency to previous reported values. Reaction time for maximum concentration of 5-HMF decreased as the temperature increased. Furthermore, the decomposition of 5-HMF was fast as the acid concentration increased. Reaction time to reach maximum concentration of levulinic acid was reduced as the acid concentration increased. Continuing to raise the temperature decreased the maximum concentration of levulinic acid and increased the amount of humins. On the basis of results, kinetic parameters help to understand mechanism of LA and 5-HMF. In addition, this study provides useful information to achieve high concentration of LA and 5-HMF from biomass.

• Journal of Appropriate Technology
• /
• v.7 no.1
• /
• pp.59-71
• /
• 2021

Hybrid hydrothermal carbonization (Hybrid HTC) technology is a proprietary thermochemical process for two or more organic wastes.The reaction time is less than two hours with temperature range 180~250℃ and pressure range 20~40bar. Thanks to accumulation of the carbon of the waste during Hybrid HTC process, the energy value of the solid fuel increases significantly with comparatively low energy consumption. It has also a great volume reduction with odor removal effect so that it is evaluated as the best solid fuel conversion technology for various organic wastes. In this study of the hybrid hydrothermal carbonization, the effect on the calorific value and yield of Cambodian mango waste were evaluated according to changes in temperature and reaction time. Through the study, parameter optimization has been sought with improving energy efficiency of the whole plant. It is decomposed in the Hydro-Carbonation Technology to Generate Gas. At this time, it is possible to develop manufacturing and production technologies such as hydrogen (H₂) and methane (CH₄). Based on the results of the study, a pilot plant (2t/day) has been proposed for future commercialization purpose along cost analysis, mass balance and energy balance calculations.

• Korean Journal of Poultry Science
• /
• v.49 no.4
• /
• pp.239-246
• /
• 2022

This study was conducted to investigate the effects of dietary γ-aminobutyric acid (GABA) and a probiotic mixture on egg production and quality, blood parameters, and stress levels (corticosterone) in Hy-Line parent stock during summer in Korea. A total of 105 Hy-Line parent stock aged 24 weeks were randomly divided into three groups, each containing thirty-five birds: control, γ-aminobutyric acid (GABA), and probiotics (1 × 10⁸/g Bacillus licheniformis, 1 × 10⁷/g Lactobacillus plantarum, and 1 × 10⁷/g Corynebacterium butyricum). The hens were fed a diet containing 50 ppm GABA or 0.1% probiotics for 6 weeks. Compared with the control group, the hen-day egg production, egg mass, and feed conversion ratio over the total period were significantly higher in the probiotic group (P<0.05). In contrast no significant differences were detected among groups with respect to egg weight, albumen height, Haugh units, yolk color, shell thickness or shell strength. Similarly, no significant difference were observed among groups with regards to biochemical profile (total cholesterol, triglyceride, glucose, total protein, aspartate aminotransferase, alanine aminotransferase, albumin, and inorganic phosphorus). However, compared with the control group, we did detect significant reductions in corticosterone levels in the GABA and probiotics groups (P<0.05). On the basis of our findings in this study, it would appear that dietary GABA and probiotics can alleviate heat stress in Hy-Line parent stock, with probiotics in particular being found to promote significant improvements in the hen-day egg production, egg mass, and feed conversion of laying hens during the summer season in Korea.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.1
• /
• pp.29-36
• /
• 2009

In this paper, the design and implementation of LNA and down-mixer using 90 nm CMOS process are presented for 60 GHz band WPAN receiver. In order to extract characteristics of the transistor used to design each elements under the optimum bias conditions, the S-parameter of the manufactured cascode topology was measured and the effect of the RF pad was removed. Measured results of 3-stages cascode type LNA the gain of 25 dB and noise figure of 7 dB. Balanced type down-mixer with a balun at LO input port shows the conversion gain of 12.5 dB within IF frequency($8.5{\sim}11.5\;GHz$) and input PldB of -7 dBm. The size and power consumption of LNA and down-mixer are $0.8{\times}0.6\;mm^2$, 43 mW and $0.85{\times}0.85\;mm^2$, 1.2 mW, respectively.

• Journal of Animal Science and Technology
• /
• v.50 no.1
• /
• pp.19-26
• /
• 2008

Heritability and genetic correlation for growth traits in Duroc pig breed were estimated using Bayesian method via Gibbs sampling. The data set consisted of 3,526 performance records at National Institute of Animal Science. For estimating those parameters using Gibbs sampling, 5,000 cycles of ‘burn-in’ period were discarded among a total of 55,000 samples. Out of the remaining 50,000 samples, 5,000 estimates by each parameter were retained and used for analyses to avoid any correlation among adjacent samples. The growth traits considered in this study were average daily gain at 30kg(ADG1), average daily gain at 90kg(ADG2), backfat thickness(BF), days to 90kg(D90) and feed conversion ratio(FC). The estimated heritabilities and their standard deviation using Gibbs sampler were 0.43±0.04, 0.49±0.038, 0.31±0.040, 0.48±0.039 and 0.62±0.086, respectively. Genetic correlations were －0.02, －0.13, －0.55 and －0.15 between ADG1 with ADG2, BF, D90 and FC, respectively, 0.16, －0.73, －0.32 between ADG2 with BF, D90 and FC respectively, 0.01, －0.08 between BF with D90, FC, respectively, and 0.23 between D90 with FC.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.3
• /
• pp.386-401
• /
• 2011

Mathematical models for various steps in coal gasification reactions were developed and applied to investigate the effects of operation parameters on dynamic behavior of gasification process. Chemical reactions considered in these models were pyrolysis, volatile combustion, water shift reaction, steam-methane reformation, and char gasification. Kinetics of heterogeneous reactions between char and gaseous agents was based on Random pore model. Momentum balance and Stokes' law were used to estimate the residence time of solid particles (char) in an up-flow reactor. The effects of operation parameters on syngas composition, reaction temperature, carbon conversion were verified. Parameters considered here for this purpose were $O_2$-to-coal mass ratio, pressure of reactor, composition of coal, diameter of char particle. On the basis of these parametric studies some quantitative parameter-response relationships were established from both dynamic and steady-state point of view. Without depending on steady state approximation, the present model can describe both transient and long-time limit behavior of the gasification system and accordingly serve as a proto-type dynamic simulator of coal gasification process. Incorporation of heat transfer through heterogenous boundaries, slag formation and steam generation is under progress and additional refinement of mathematical models to reflect the actual design of commercial gasifiers will be made in the near futureK.

• Journal of Ocean Engineering and Technology
• /
• v.26 no.3
• /
• pp.33-38
• /
• 2012

The aim of this experimental study was to analyze the effect of the shape parameters and chamber pressure of a land-based oscillating water column (OWC) in regular incident waves. The magnitude of the free surface elevations inside the chamber was measured in a two-dimensional wave tank for various chamber skirt drafts and bottom slope angles. The surface elevations were also measured under both open chamber and partially open chamber conditions. From these measurements, the optimum shape of the OWC device could be predicted for the maximum wave energy conversion efficiency. It was found that the resonance frequency of the OWC system associated with incident waves moved toward the long wave region with increments of the draft of the chamber skirt and bottom slope. The behavior of the free surface elevation inside the chamber was also found to be dependent on the chamber pressure.