• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.87-94
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• 1998

After we made the computer source code with mathematical model of Muramatsu et al. that was expressed by the set of simultaneous first-order ordinary differential equations in evaporation-pyrolysis zone of cigarette, we simulated the distribution profiles of temperature and density of flue-cured tobacco. Those equations were solved numerically with the Runge-Kutta-Gill algorithm assuming step size of 0.025mm by Muramatsu at at,, but in this study the advanced algorithm of Runge-Kutta 4th Order assuming step size of 0.0005mm. The initial conditions and physical parameters of Muramatsu et at. were used for solving them. The calculated values corresponded well with results of Muramatsu et al., especially the gradient of the temperature profile increased with smoldering speed and the thickness of the evaporation-pyrolysis zone decreased with increasing of smoldering speed. On the other hand, the temperature gradient decreased with increasing of the effective thermal-conductivity value and the thickness of the evaporation-pyrolysis zone increased with the effective thermal-conductivity value.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.206-212
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• 2009

Chemical behaviors of each surface material for interior facilities affect to fire initiation and growth in general fire situation. These chemical behaviors were characterized by thermal properties (Heat release rate, Pyrolysis rate, specific heat, etc) which could be derived from experimental test. Especially, Heat release rate which indicates aspect of fire size is one of the most important property to asses fire hazard and protection needs. The cone calorimeter test (ISO 5660) has recently assumed to a dominant role in bench scale fire testing to obtain the Heat release rate of materials. This value could be calculated by the 'Oxygen Consumption Method' under various producing irradiances to each surface of materials. In this study, Process of the cone calorimeter test was simulated by Pyrolysis model of FDS (Fire Dynamics Simulator by NIST) base on the ISO 5660 international standard. Then, we could estimate the simulation method of FDS in case of single materials through the comparative study with test results.

• The KSFM Journal of Fluid Machinery
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• v.14 no.1
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• pp.34-41
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• 2011

Fire characteristics can be analyzed more realistically by using more accurate properties related to the fire dynamics and one way to acquire these fire properties is to use one of the inverse property estimation techniques. In this study two optimization algorithms which are frequently applied for the inverse heat transfer problems are selected to demonstrate the procedure of obtaining pyrolysis properties of charring material with relatively simple thermal decomposition. Thermal decomposition is occurred at the surface of the charring material heated by receiving the radiative energy from external heat sources and in this process the heat transfer through the charring material is simplified by an unsteady 1-dimensional problem. The basic genetic algorithm(GA) and repulsive particle swarm optimization(RPSO) algorithm are used to find the eight properties of a charring material; thermal conductivity(virgin, char), specific heat(virgin, char), char density, heat of pyrolysis, pre-exponential factor and activation energy by using the surface temperature and mass loss rate history data which are obtained from the calculated experiments. Results show that the RPSO algorithm has better performance in estimating the eight pyrolysis properties than the basic GA for problems considered in this study.

• Journal of Energy Engineering
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• v.14 no.1
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• pp.1-10
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• 2005

The combustion reactivity of char depending on the pyrolysis pressure was investigated with Pressurized Thermogravimetric Analyser. The amounts of volatiles released at pyrolysis pressure of 1, 8 and 15 atm were, first, measured with Alaska, Adaro and Denisovsky coals. Reactivities of chars produced at var-ious pyrolysis pressure were evaluated at atmospheric pressure and 500℃, and analysed in terms of char crystal structure, surface area, pore characteristics and chemical composition of char. Finally, the combustion reactivities of three chars were examined at pressure of 1 atm, 8 atm and 15 atm. From this study, it was recognized that the amount of volatiles released decreases with increase in pyrolysis pressure, and reaction rate of char produced at higher pyrolysis pressure was lower than that at lower pyrolysis pressure. It might be resulted from the difference in char surface area and pore characteristics rather than char crystal structure and chemical characteristics. At 15 atm, kinetic parameters of Alaska char were obtained with the grain model, and these were 56.8 KJ/mole for activation energy and 222.34 (1/min) for frequency factor.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.415-423
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• 2007

Pyrolysis characteristics of sawdust and rice husk as biomass resources in a thermogravimetric analysis were determined. Experiments were carried out with a linear heating rate under inert atmosphere of $N_2$ gas. Pyrolysis of the biomass can be classified as a lower temperature reaction zone where the major component of holocellulose is thermally decomposed and a high temperature reaction zone where lignin is thermally decomposed. The obtained data was analyzed by the two-step consecutive reaction model. Activation energies of sawdust and rice husk are found to be respectively 82.5 kJ/mol and 85.1kJ/mol in the low temperature zone according to the first order reaction model and 19.7 kJ/mol, 22.0 kJ/mol in the high temperature zone according to the three-way transport model. The reaction rate constant with variation of heating rate can be well predicted by the kinetic compensation relation of Gaur-Reed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.196-202
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• 2018

In this study, we investigated phosphate removal efficiency according to pretreatment (pyrolysis temperature, pyrolysis time, particle size) of oyster shells as a basic study for their recycling. And XAFS analysis and isothermal adsorption experiments were performed to investigate the phosphate removal characteristics of oyster shells. As a result, the removal efficiency was good at $600^{\circ}C$ pyrolysis temperature with 6 hour pyrolysis time and 0.355 ~ 0.075 mm particle size. Isothermal adsorption experiments showed that the Langmuir model is suitable for adsorption of oyster shells. XAFS analysis showed that calcium phosphate formed on the oyster shell pyrolyzed at $600^{\circ}C$. In other words, it was confirmed that the formation of calcium phosphate by the calcium ion elution of the oyster shell contributes to the decrease of phosphate concentration.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.585-593
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• 2011

Actual fire test under a laboratory and fire simulation by using computer are considered into main methodology in order to estimate and predict fire size of railway train. Even if practical fire size could be obtained from the full-model railway car test such as a large scale cone-calorimeter test, it is not always possible and realistic due to that expensive cost and attendant dangers could in no way be negligible. In this point of view, fire simulation analysis method based on the computational fluid dynamics could be proposed as an alternative and it seems to be also efficient and reasonable. However, simulation results have to be verified and validated in accordance with the proper procedure including comparing analysis with the actual fire test. In this paper, fire load and growth aspect was investigated through the room corner test (ISO 9705) for the mock-up model of the actual railway car. Then, it was compared with the output data derived from the simulation by using Pyrolysis Model of the FDS (Fire Dynamics Simulator, by NIST) for the exact same domain and condition corresponding with pre-performed room-corner test. This preliminary verified and validated fire modeling method could enhance the reliability of output data derived from the fire simulation under the similar domain and condition.

• Journal of Environmental Science International
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• v.6 no.4
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• pp.399-407
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• 1997

The pyrolysis reactions of atomic hydrogen with chloroform were studied In a 4 cm 1.6. tubular flow reactor with low flow velocity 1518 cm/sec and a 2.6 cm 1.4. tubular flow reactor with high flow velocity (1227 cm/sec). The hydrogen atom concentration was measured by chemiluminescence titration with nitrogen dioxide, and the chloroform concentrations were determined using a gas chromatography. The chloroform conversion efficiency depended on both the chloroform flow rate and linear flow velocity, but 416 not depend on the flow rate of hydrogen atom. A computer model was employed to estimate a rate constant for the initial reaction of atomic hydrogen with chloroform. The model consisted of a scheme for chloroform-hydrogen atom reaction, Runge-Kutta 4th-order method for Integration of first-order differential equations describing the time dependence of the concentrations of various chemical species, and Rosenbrock method for optimization to match model and experimental results. The scheme for chloroform-hydrogen atom reaction Included 22 elementary reactions. The rate constant estimated using the data obtained from the 2.6 cm 1.4. reactor was to be 8.1 $\times$ $10^{-14}$ $cm^3$/molecule-sec and 3.8 $\times$ $10^{-15}$ cms/molecule-sec, and the deviations of computer model from experimental results were 9% and 12% , for the each reaction time of 0.028 sec and 0.072 sec, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.710-716
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• 2013

New and renewable energy sources have drawn attention because of climate change. Many studies have been carried out in waste-to-energy field. Fast pyrolysis of waste lignocelluosic biomass is one of the waste-to-energy technologies. Bubbling fluidized bed (BFB) reactor is widely used for fast pyrolysis of the biomass. In BFB pyrolyzer, bubble behavior influences on the chemical reaction. Accordingly, in the present study, hydrodynamic characteristics and fast pyrolysis reaction of waste lignocellulosic biomass occurring in a BFB pyrolyzer are scrutinized. The computational fluid dynamics (CFD) simulation of the fast pyrolysis reactor is carried out by using Eulerian-Granular approach. And two-stage semi-global kinetics is applied for modeling the fast pyrolysis reaction of waste lignocellulosic biomass. To summarize, generation and ascendant motion of bubbles in the bed affect particle behavior. Thus biomass particles are well mixed with hot sand and consequent rapid heat transfer occurs from sand to biomass particles. As a result, primary reaction is observed throughout the bed. And reaction rate of tar formation is the highest. Consequently, tar accounts for 66wt.% of the product gas. However, secondary reaction occurs mostly in the freeboard. Therefore, it is considered that bubble behavior and particle motions hardly influences on the secondary reaction.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.4
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• pp.385-391
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• 2014

A control system for ultrasonic spray pyrolysis deposition was developed that can coat a large size glass panel with a transparent conductive oxide. It consists of several ultrasonic atomizer devices to cover a large area and a host computer for individually controlling the devices. The sub-controller in an ultrasonic atomizer device can adjust the flow rate of the atomized conductive oxide gas by setting the flow rate of the solution and regulating the level of the solution in the tank. To construct a feedback control loop for level regulation, a level sensor that utilized an infrared distance sensor and an electric circuit for adjusting the ultrasonic oscillator were developed. The host program was also developed, which can monitor and control the sub-controllers. A proportional-integral controller was developed for a simplified model, and its operation was verified through an experiment.