• Journal of Environmental Science International
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• v.6 no.3
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• pp.267-276
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• 1997

It has been studded that combustion and the production of air pollution of anthracite - bituminous coal blend In a fluidized bed coal combustor, The objects of thIns study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and Imported h19h calorific bltununous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010kca1/kg and the Imported high grade bituminous coal with beating value of 6,520kca1/kg. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300sc1h which was the fastest. It has been found that $O^2$ and $CO^2$ concentration were reached steady state at about 100 minute. It has been found that $O^2$ concentration decreased and $CO^2$ concentration increased as the height of fluidlzed bed Increased. It was found that splash zone was mainly located from 25cm to 35cm above distributor. Also, as anthracite traction Increased, the mass of elutrlatlon particles Increased, and $CO^2$ concentration decreased. As gk flow rate Increased,$O^2$ concentration decreased and $CO^2$ concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approldmately high In the case of One Particles. As anthracite traction and k now rate Increased, elutriation ratio Increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was Increased. Regardless of anthracite fraction, size distribution of Ued material from discharge was almost constant. Over bed temperature 85$0^{\circ}C$ and excess air 20% , the difference of combution efficiencies were little. It is estimate that the combustion condition In anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 85$0^{\circ}C$, the excess air 20%.

• Resources Recycling
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• v.9 no.1
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• pp.27-35
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• 2000

Characteristics of pyrolytic gasification were examined for the waste tire and 7 types of waste synthetic resin, using a bench scale experimental facility. the product gas temperature of waste tires was $150~300^{\circ}C$ and the temperature profile in the combustion zone of the lower reactor part tended to be clearly distinguished from that in the gasification zone of the upper part. However, in the case of waste synthetic resins, there were no clear distinction and temperature fluctuation was severe, depending on the reaction time. Product gas quantity, which depends on that of supplied (1st) air, was found to be 105~135% of the 1st air amount at the steady state. The concentration of noncombustible components in product gas was 80~90 vol.% and the high heating value of the product gas calculated from gas compositions was 1,500~3,000 kcal/N㎥ for waste tire, and 300~2,900 kcal/N㎥ for waste synthetic resins, respectively. Heating value of product gas and combustible gas concentration were increased in proportion to 1st air amount when 1st air amount is below $0.35N\textrm{m}^3$/min.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1584-1588
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• 2018

During hyperthermia therapy, cancer cells are heated to a temperature in the range of $40{\sim}45^{\circ}C$ for a defined time period to damage these cells while keeping healthy tissues at safe temperatures. Prior to hyperthermia therapy, the amount of heat energy transferred to the cancer cells must be predicted. Among various non-invasive methods, the thermal prediction method using the specific absorption rate (SAR) is the most widely used method. The existing methods predict the thermal distribution by using a single constant for the mass density in one organ through assignment. However, because the SAR and the bio heat equation (BHE) vary with the mass density, the mass density of each organ must be accurately considered. In this study, the mass density distribution was calculated using the relationship between the Hounsfield unit and the mass density of tissues in preceding research. The SAR distribution was found using a quasi-static approximation to Maxwell's equation and was used to calculate the potential distribution and the energy distributions for capacitive RF heating. The thermal distribution during exposure to RF waves was determined by solving the BHE with consideration given to the considering contributions of heat conduction and external heating. Compared with reference data for the mass density, our results was within 1%. When the reconstructed temperature distribution was compared to the measured temperature distribution, the difference was within 3%. In this study, the density distribution and the thermal distribution were reconstructed for the agar phantom. Based on these data, we developed an algorithm that could be applied to patients.

• KIEAE Journal
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• v.14 no.4
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• pp.111-117
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• 2014

In South Korea, the government has recently enforced regulations associated with buildings. Temperature restriction in indoor environment is one of the common ways of energy reduction in order not to dissipate heating and cooling energy; however the people who are in restricted temperature feels uncomfortable. Furthermore, occupants cannot feel the same thermal sensation even they are in the same place. For the reason, occupants should express their thermal sensation and HVAC system should be able to apply their demand. It is proved by an adaptive principle. The adaptive model means that people react in ways which tend to restore their comfort, when change occurs such as to produce discomfort. In order to design HVAC control strategies based on adaptive model, we designated an existing office building as a reference building to gather data from actual field. Furthermore, we gathered occupants' thermal sensation and clothing insulation in real-time. We filtered the data with Kalman's filter method. The data was reasonable when there is an alarm messages for asking questionnaire. The response ratio were different in occupants' thermal condition. In conclusion, the filtered occupants' thermal sensation can be used as a real time HVAC control and input value of HVAC control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2628-2634
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• 2014

Vehicle washer heater system is more widely adopted to defrost a window or to clear the windshield glass in winter season. The washer heater system should be designed to heat up washer fluid rapidly to the target temperature for only a short time. A numerical analysis has been carried out to analyze the heat transfer characteristics with materials of inside parts in vehicle washer heater system with filler and flow path. ANSYS - FLUENT software is employed for the analysis. The axial symmetry model is three-dimensional and unsteady. It applies to the coupled method which is one of pressure based. Through this result, it was obtained to find the optimal material condition for the filler and flow path in washer system. For material of filler, the air with lower density was heated more rapidly rather than silicon carbide(SiC). For material of flow path, copper with the heat transfer coefficient of approximately four times greater than the nickel gives us higher efficiency. That is the reason why the heating time of methanol was reduced to make uniform temperature in washer heater system.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.217-221
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• 2011

Glass-ceramic materials, which consist of glass matrix phase containing crystalline ${\beta}-Ca_3(PO_4)_2$ and ${\beta}-Ca_2P_2O_7$, have been prepared by heating at $750-900^{\circ}C$ of calcium phosphate invert glasses in the silica-free $CaO-P_2O_5-TiO_2-Na_2O$, system. With increasing heating temperature from 750 to $900^{\circ}C$, the crystallite size of precipitated ${\beta}-Ca_3(PO_4)_2$ in glass with $55CaO{\cdot}35P_2O_5{\cdot}3TiO_2{\cdot}7Na_2O$ (mol%) composition increased from 48 to 91 nm. With the extension of the immersion time in dilute acetic acid solution (pH = 5) to ${\geq}$200 min, the degree of dissolution of $Ca^{2+}$ and $P^{5+}$ ions in the glass-ceramics was linearly increased and the solution was constantly maintained at pH = ~7. Biomimetic nanostructured (62-88 nm in average dia.), sphere-shaped hydroxyapatite was homogeneously formed on the surface of the glass-ceramics when socked for 7-14 days in a Hanks' solution, indicating bioactivity of the prepared glass-ceramics.

• Polymer(Korea)
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• v.33 no.2
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• pp.183-188
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• 2009

Structural rearrangements of uni-axially deformed polyethylenes containing 1-octene comonomer and HDPE upon heating were investigated by time-resolved small and wide angle X-ray scattering techniques. During heating, structural changes including crystal transformation and lamellar rearrangement noted were very different depending on the comonomer contents. At low comonomer content below 2 wt%, inverse martensitic transformation of crystal lattice from monoclinic to orthorhombic cell and the rearrangement of broken lamellar units into more ordered and perfect lamellar stacks were noted with the temperature increase. At high contents above 9.5 wt%, however, polyethylene copolymers showed neither the crystal transformation nor lamellar rearrangement that can be attributed to low crystallinity and high content of branch units.

• Journal of Biosystems Engineering
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• v.42 no.1
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• pp.56-61
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• 2017

Purpose: High energy requirement and long cooking time are limiting consumption of pigeon pea (Cajanus cajan), a nutritious food. This study was performed to estimate energy and time demand by different methods of cooking pigeon pea. Methods: Pigeon pea (150 g) was soaked in 2.0 L of water at ambient temperature ($29{\pm} 2^{\circ}C$) to determine hydration behavior. Cooking experiments were conducted using aluminum and pressure-cooking pots. Efficiency of cooking was evaluated using four types of cooking appliances (kerosene, liquefied petroleum gas (LPG), electric, and charcoal stoves). Normal (continuous heating until the food was satisfactorily cooked) and control (controlling the energy input to closely match the actual energy required) cooking were conducted. Energy requirement and duration of cooking were determined using standard procedures. Results: Soaking increased moisture content from 11.99 to 30.01% in 90 min, while water absorption rate decreased with soaking duration. In cooking 150 g of pigeon pea using kerosene stove, presoaked normal pressure-pot cooking method consumed the least energy (10 800 kJ) and time (205 min), while unsoaked normal cooking consumed the highest energy (18 450 kJ) and time (336 min). Using LPG stove, unsoaked normal cooking method required the highest energy (52 470 kJ), while presoaked control pressure-pot required the least energy (14 405 kJ). For electric stove, the lowest energy (15 560 kJ) and shortest duration (105 min) were recorded during control cooking of presoaked sample in the pressure-pot. Conclusions: Control cooking was not practicable using charcoal stove. Generally, kerosene stove consumed the least energy, while electric stove was found to have the shortest duration of cooking.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.6
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• pp.297-305
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• 2017

Air-source heat pumps are widely used in residential heating systems. However, the decrease in the capacity of the heat pump is unavoidable when operating at very low and high ambient temperatures. The vapor injection technique is considered a promising technology to overcome this problem. Recent research on vapor injection cycles have mainly adopted a scroll compressor with an internal heat exchanger at severe operating conditions. This study measured the COP and EER of a gas injection heat pump using a flash tank with an inverter-driven rotary compressor at severe operating conditions. Compared to non-injection heat pumps, the heating capacity and COP of the gas injection heat pump improved up to 15% and 2.9%, respectively, at outdoor temperatures of $-10^{\circ}C$ to $7^{\circ}C$. The cooling capacity of the gas injection heat pump was 11% higher than the non-injection heat pump at an outdoor temperature of $35^{\circ}C$. At the same time, the EER of the gas injection heat pump was similar to that of the non-injection heat pump.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.393-400
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• 2016

High frequency induction heating (HFIH) is used in many industries and has a number of advantages, including reliability and repeatability. It is a non-contact method of providing energy-efficient heat in the minimum amount of time without using a flame. Recently, HFIH has been actively studied using the finite element method (FEM), however, these studies only focused on the accuracy of the analysis. In this paper, we can measure joule heat distributions by the electromagnetic analysis for HFIH and the temperature distribution from the heat transfer analysis by applying joule heat for a sprocket. The sprocket is heated over $850^{\circ}C$ due to joule heat and then cooled to under $200^{\circ}C$ by using cooling $20^{\circ}C$ water. These processes were used to calculate the FEM and then compared to our experimental results. The calculated outcome may be used to predict hardening depth in HFIH.