• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.723-730
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• 2017

The batch experiments by response surface methodology (RSM) have been applied to investigate the influences of operating parameters such as temperature, initial concentration, contact time and adsorbent dosage on 2,4-dichlorophenol (2,4-DCP) adsorption with an activated carbon prepared from waste citrus peel (WCAC). Regression equation formulated for the 2,4-DCP adsorption was represented as a function of response variables. Adequacy of the model was tested by the correlation between experimental and predicted values of the response. A fairly high value of $R^2$ (0.9921) indicated that most of the data variation was explained by the regression model. The significance of independent variables and their interactions were tested by the analysis of variance (ANOVA) and t-test statistics. These results showed that the model used to fit response variables was significant and adequate to represent the relationship between the response and the independent variables. The kinetics and isotherm experiment data can be well described with the pseudo-second order model and the Langmuir isotherm model, respectively. The maximum adsorption capacity of 2,4-DCP on WCAC calculated from the Langmuir isotherm model was 345.49 mg/g. The rate controlling mechanism study revealed that film diffusion and intraparticle diffusion were simultaneously occurring during the adsorption process. The thermodynamic parameters indicated that the adsorption reaction of 2,4-DCP on WCAC was an endothermic and spontaneous process.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.256-260
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• 1992

This study was conducted to calculate and predict the shelf-life of meat sausage through physicochemical and biological analysis. Judging from physico-chemical components, it can be found out the most effective indicator in meat sausage. And also, the materials used for packaging is cellulose #23 in inner-packaging and CN/HDPE laminating film in outer-packaging. The changes of the most effective indicator were discussed through the method of kinetic analysis. Judging from physico-chemical components, VBN was the most available component in quality judgement of meat sausage and their upper limiting contents were 20 mg%. It is possible to calculate and predict the shelf-life of meat sausage through the regression equation and $Q_{10}$ value. As a result, the shelf-life prediction was $58{\sim}63$ days at $10^{\circ}C$, $47{\sim}51$ days at $20^{\circ}C$ and 26 days at $40^{\circ}C$, respectively, but the difference between two methods showed about $4{\sim}5$ days. $Q_{10}$ value on the changes contents was 1.35 at acceralated temperature $40^{\circ}C$. The reaction rate of VBN contents could be interpreted as a first order reaction that divided into 2 periods with different reaction rate constants. The corresponding Arrhenius activation energies were 2.959 Kcal/mole and 3.632 Kcal/mole, respectively.

• Journal of Pharmaceutical Investigation
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• v.27 no.4
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• pp.253-263
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• 1997

To investigate the interaction of omeprazole (OMP) and meglumine (MEG), a complex was prepared by freeze-drying method in ammoniacal aqueous medium at room temperature and subjected to IR, DSC, and 1H NMR analysis. In addition, the stability of the complex was tested by accelerated stability analysis, and the dissolution rate of both powder and enteric coated was determined pellet by paddle method. The results are as follows; i) IR, DSC, and $^{1}H$ NMR studies indicate the formation of inclusion complex between OMP and MEG probably by electrostatic forces as $[OMP]\;[MEGH]^+$ form in a stoichiometric ratio (1:1) of OMP : MEG. ii) The dissolution rate of enteric coated OMP-MEG complex pellet in simulated enteric fluid was 90.6% in 10 minutes, which may satisfy the requirement for the regulation of dissolution. iii) OMP-MEG complex were decomposed according to pseudo 1st order kinetics: while the decomposition of OMP showed a rate constant $(k_{25^{\circ}C})$ of $5.13{\times}10^{-4}{\cdot}\;day^{-1}$, a half-life$(t_{1/2})$ of 1,350 days, a shelf-life$(T_{90%})$ 205 days and an activation energy of 23.53 kcal/mole. OMP-MEG complex inhibited a rate $(k_{25})$ of $2.92{\times}10^{-4}{\cdot}\;day^{-1}$, a half-life$(t_{1/2})$ of 2,373 days, a shelf-life $(T_{90%})$ of 306 days and an activation energy of 20.18 kcal/mole. iv) OMP was stabilized markedly by the formation of OMP-MEG complex between OMP and MEG, and the humidity increased the stability of OMP-MEG complex by decreasing the decomposition rate$(k_{50^{\circ}C})$ from $1.27{\times}10^{-2}{\cdot}\;day^{-1}$ at 31% R.H. to $2.54{\times}10^{-2}{\cdot}\;day^{-1}$ at 90% R.H.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.4
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• pp.65-74
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• 2002

This Study was investigated operating condition of pyrolysis processing for sludge disposal in sewage treatment plant. Important parameters studied include running time of pyrolysis, run time of dry and pyrolysis processing, water content of sewage sludge, solids amount of sewage sludge(TS%), condition of pyrolysis temperature. Most degradation reaction of sewage sludge are first order, it assumed first order and elucidated the kinetics. This was the basis of characteristics analysis of sludge degradation mechanism. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas product components was observed. Main components of gas and carbon product are a little difference with pyrolysis temperature, but it consist of $CH_4$, $C_2H_4$, $C_3H_8$, $C_4H_{10}$, toluene, $C_6H_6$, $SO_2$, CO etc. The gas of $C_1-C_4$ yield increased along with degradation temperature of $670^{\circ}C$ and oil yield decreased of $C_6H_6$ and $C_6H_5OH$ with temperature of $600^{\circ}C$. Particularly, low value added char yield 134kg/t at $670^{\circ}C$, but increased to 194kg/t at pyrolysis temperature of $600^{\circ}C$. In the result of elementary analysis on it, it is mainly composed of carbon. From this fact, in pyrolysis of sludge, it comfirmed that carbonization reaction occur at high temperature well.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.547-554
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• 2010

In this study, new manganese oxide (i.e., black-birnessite) particles with nanostructures were prepared and its physico-chemical properties and oxidative-transformation efficiency on 1,4-naphthoquinine(1,4-NPQ) in the presence of reactive mediator was investigated. The results were also compared with that of the manganese oxide (i.e., brown-birnessite) particles synthesized by classical McKenzie method. Analysis of XRD and SEM data show that the particles are a single phase corresponding to a birnessite-based manganese oxide with cotton ball-like shapes containing nanofibers. In batch experiments, removals of 1,4-NPQ by the black-birnessite follows pseudo-first-order kinetics and the rate constant values obtained are greater about 2.3 times than that of the brown-birnessite in spite of its lower surface area (41.0 vs 19.80 $m^2/g$). The results can be explained by the higher crystallinity and nano structured features of the back-birnessite particles, which give higher reactivity for the removals of the quinone compound. HPLC analysis of the reaction products confirmed that the balck-birnessites removed 1,4-NPQ through cross-coupling reaction in the presence of catechol as a reactive mediator.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.404-409
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• 2016

Thermal Characteristics and kinetic parameters of $LaMnO_3$ synthesis reaction were investigated by means of TGA (Thermogravimetric analysis) at non-isothermal heating conditions (5.0, 10.0, 15.0 and 20.0 K/min). The reaction was occurred rapidly at 450~600K (X=0.4~0.7) depending on the heating rate. Activation energy for the synthesis of $LaMnO_3$ from the precursor, which was determined by different method such as Friedman, Ozawa-Flynn-Wall and Vyazovkin methods, was in the range of 23~243 kJ/g-mol depending on the fractional conversion level and estimation method. The reaction order decreased with increasing heating rate and fractional conversional level. The average reaction order was 4.50 in case of X=0.1~0.3, while it was 1.87 in case of X=0.7~0.9, respectively. The value of frequency factor of reaction rate increased with inceasing heating rate and fractional conversion level. The aveage value of frequency factor was 205.6 ($min^{-1}$) when X=0.1~0.3, while it was 475.2 ($min^{-1}$) when X=0.7~0.9, respectively.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.676-682
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• 2009

Devolatilization of the Refuse Derived Fuel(RDF) which is produced at WonJu in Korea was characterized in air atmosphere with variation of heating rate(10, 20 and $30^{\circ}C/min$) in TGA. The results of TG Analysis have shown that the pyrolysis and char combustion of the RDF occurred in the range of $350{\sim}700^{\circ}C$ depending on the heating rate. Activation energy of the RDF which was determined by using Friedman and Ozawa-Flynn-Wall method was in the range of 14.44~18.40 kcal/mol. Also, reaction order(n) and pre-exponential factors(A) were 1.219 and $3.02{\times}10^5$ by using Friedman method, respectively. In order to find out the devolatilization mechanism of the RDF, twelve solid-state mechanisms defined by Coats Redfern Method were tested. The results of the Coats Redfern Method have shown that chemical reaction is the effective mechanism by comparison with the value of the activation energy which was derived from the Friedman and Flynn-Wall-Ozawa method and correlation coefficient from twelve solid-state mechanisms of Coats Redfern Method. The solid state decomposition mechanism of the RDF was found to be a decelerated $F_1$ type, random nucleation with one nucleus on the individual particle.

• Journal of Life Science
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• v.19 no.9
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• pp.1299-1303
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• 2009

The purpose of this study was to analyse the gait characteristics of stroke patients walking on a Zebris system, through quantitative three-dimensional biomechanical analysis. They underwent a continuous rehabilitation training program (RTP). A comparison was made between 3 month and 6 month RTP participants. Their ages were between 60 and 65. The data were analyzed by t-test. The result of comparative analysis of the two groups can be summarized as below. Temporal-spatial data, sagittal plane angular kinematics data, and peak ground reaction force and max pressure data showed that there were no significant differences between the 3 month RTP group and the 6month RTP group (Table 2, Table3, Table 4). It can be suggested that patients with hemiplegia after stroke can improve their walking function through continuous RTP participation.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.3
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• pp.85-89
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• 2014

TTI is a small label of which the color changes by time-temperature history during food storage. The food shelf life (SL) was compared with that of TTI, the time for TTI to reach the end-point of its color change, for the various discrepancies in two Arrhenius activation energies (Ea), an important parameter of temperature dependence. The SL of TTI and food were mathematically simulated, based on zero-order and first-order kinetics, respectively. In the case Ea of food was smaller than that of TTI, the SL of food was larger than that of TTI, meaning TTI reaches the end-point of color change earlier even though food is still fresh. In the case of Ea of food > Ea of TTI, the food reaches the SL earlier than the TTI. In addition, the magnitude of ${\Delta}Ea$ between food and TTI led to the bigger ${\Delta}SL$. To be safe, $SL_{Food}$ > $SL_{TTI}$ would be practical although $SL_{Food}{\fallingdotseq}SL_{TTI}$ is ideal.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.386-398
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• 2004

Objectives: The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue Light Emitting Diode Light Curing Units (LED LCUs) compared with conventional halogen LCUs. Materials and Methods: First, thermal analysis was performed by a differential scanning calorimeter (DSC). The LED LCU (Elipar Freelight, $320{\;}mW/\textrm{cm}^2$) and the conventional halogen LCU (XL3000, $400{\;}mV/\textrm{cm}^2$) were used in this study for curing three composite resins (SureFil, Z-250 and AEliteFLO). Second. the degree of conversion was obtained in the composite resins cured according to the above curing mode with a FTIR. Third, the measurements of depth of cure were carried out in accordance with ISO 4049 standards. Statistical analysis was performed by two-way ANOVA test at 95% levels of confidence and Duncan's procedure for multiple comparisons. Results: The heat of cure was not statistically different among the LCUs (p > 0.05). The composites cured by the LED (Exp) LCUs were statistically more slowly polymerized than by the halogen LCU and the LED (Std) LCU (p < 0.05). The composite resin groups cured by the LED (Exp) LCUs had significantly greater degree of conversion value than by the halogen LCU and the LED (Std) LCU (p =0.0002). The composite resin groups cured by the LED (Std) LCUs showed significantly greater depth of cure value than by the halogen LCU and the LED (Exp) LCU (p < 0.05).