• Korean Journal of Human Ecology
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• v.5 no.2
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• pp.55-74
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• 2002

This study, observing each respectively packaged Kongdduk during 12-day storing period and comparing it with unpackaged Kongdduk, through a cross-sectional view of its fiber and temperament, through a sensory evaluation rheometer measurement of rheological change depending on storing period and packaging type and through the organic acid content, micro-organic change, and retrogressive process. The results are as follows: 1. Kongdduk made of bean oil shows better chewiness, cohesiveness, and moistness than Kongdduk made of bean flour while Kongdduk made of bean flour shows better rheological properties as to roasted nutty taste or roasted nutty order. 2. The test of the cutted loaves of Kongdduk shows that adding oil of proper proportion to the dough of steamed rice cake in accordance with the amount of rice flour has a good influence on rheological properties of softness. 3. Rice cakes were prepared by addition of yellow soybean flour or peanut flour and packaged with CMP or VP, and their physical characteristics were monitored by sensory evaluation and mechanical measurement while storing for 6 days. For VP samples, yellow soybean rice cake showed little changes in cohesiveness, moistness and chewiness for 6 days of storage, while pure rice cake and peanut rice cake showed an increase in strength and hardness from the 4th day of storage. In case of CMP, yellow soybean rice cake hardly showed a difference in cohesiveness, moistness and chewiness for 6 days, while pure rice cake and peanut rice cake showed a significant difference from the 4th day in sensory evaluation. 4. For rheometer measurement, yellow soybean rice cake with CMP or VP showed little changes in strength or hardness for 6 days, while peanut rice cake and pure rice cake showed a drastic decrease in cohesiveness, from the End day and adhesiveness from the 4th day of storage. As there was no remarkable difference or deterioration for 6 days of storage in yellow soybean rice cake between CMP and VP, the ingredients of rice cakeappeared to be more important than the type of packaging in terms of quality deterioration of rice cake. 5. As the storing period passed by, organic acid is detected less at CMP-packaged Knngdduk than at wrapped. and its increasing speed proves to be slower as well. 6. The one wrapped with plyethylene film began to get moldy from pure rice cake or Kongdduk (rice cake mixed with yellow soybean or peanut) after 6 days, and more and more modly after 9 daysor after 12 days, but the CMP-packaged ones didn't get modly until 12 days or more. 7. CMP-packaged Kongdduk showed higher enthalpy of retrogradation than PE-wrapped one. As storing Period Passed by, Kongdduk,s enthalpy grew high. That is to say, it shows that Kongdduk got retrograded.

• Composites Research
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• v.28 no.4
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• pp.168-175
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• 2015

Recently, the applications of carbon fiber reinforced plastics (CFRPs) have become broader than ever when it comes to such industries as automotive, ships, aerospace and military because of their lightweight-ness and high mechanical properties. Thermosetting plastics like epoxy are frequently used as the binding matrix in CFRPs due to their high hardness, wetting characteristics and low viscosity. However, they cannot melted and remolded. For this reason, thermosetting plastic wastes have caused serious environmental problems with the production of fiber reinforced plastics. Thus, many studies have focused on the carbon fiber reinforced thermoplastics (CFRTPs) and recycling carbon fiber. In this study, recycled carbon fiber (RCF) was prepared from CFRPs using a pyrolysis method, which was employed to separate resin and carbon fiber. The degree of decomposition for epoxy resin was confirmed from thermal gravimetric analysis (TGA) and scanning electron microscope (SEM). The RCF was cut and ground to prepare a carbon fiber composite sheet (CFCS). CFCS was manufactured by applying recycled carbon fibers and various thermoplastic fibers. Various characterizations were performed, including morphological analyses of surface and cross-section, mechanical properties, and crystallization enthalpy of CFCS at different cooling conditions.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.112-118
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• 2018

Adsorption equilibrium, kinetic and thermodynamic parameters of a brilliant green from aqueous solutions at various initial dye concentration (10~30 mg/L), contact time (1~24 h) and temperature (298~318 K) on zeolite were studied in a batch mode operation. The equilibrium adsorption values were analyzed by Langmuir, Freundlich and Dubinin-Radushkevich model. The results indicate that Langmuir and Freundlich model provides the best correlation of the experimental data. Base on the estimated values of Langmuir dimensionless separation factor ($R_L=0.041{\sim}0.057$) and Freundlich constant (1/n=0.30~0.47), this process could be employed as effective treatment method. calculated values of adsorption energy by Dubinin-Radushkevich model were 1.564~1.857 kJ/mol corresponding to physical adsorption. The adsorption kinetics of brilliant green were best described by the pseudo second-order rate model and followed by intraparticle diffusion model. Thermodynamic parameters such as activation energy, free energy, enthalpy and entropy were calculated to estimate nature of adsorption. negative Gibbs free energy (-10.3~-11.4 kJ/mol), positive enthalpy change (49.48 kJ/mol) and Arrehenius activation energy (27.05 kJ/mol) indicates that the adsorption is spontaneous, endothermic and physical adsorption process, respectively.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.96-102
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• 2014

Adsorption of metanil yellow onto granular activated carbon were studied in a batch system. Various operation parameters such as adsorbent dosage, pH, initial concentration, contact time and temperature were optimized. Experimental equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm. The equilibrium process was described well by Freundlich isotherm model. From determined separation factor (1/n), adsorption of metanil yellow by granular activated carbon could be employed as effective treatment method. By analysis of kinetic experimental data, the adsorption process were found to confirm to the pseudo second order model with good correlation and the adsorption rate constant ($k^2$) decreased with increasing initial concentration. Thermodynamic parameters like activation energy, change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The activation energy was determined as 23.90 kJ/mol. It was found that the adsortpion of metanil yellow on the granular activated carbon was physical process. The negative Gibbs free energy change (${\Delta}G=-2.16{\sim}-6.55kJ/mol$) and the positive enthalpy change (${\Delta}H=+23.29kJ/mol$) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.679-686
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• 2019

Characteristics of adsorption equilibrium, kinetic and thermodynamic of aniline blue onto activated carbon from aqueous solution were investigated as function of initial concentration, contact time and temperature. Adsorption isotherm of aniline blue was analyzed by Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich models. Langmuir isotherm model fit better with isothermal data than other isotherm models. Estmated Langmuir separation factors ($R_L=0.036{\sim}0.068$) indicated that adsorption process of aniline blue by activated carbon could be an effective treatment method. Adsorption kinetic data were fitted to pseudo first order model, pseudo second order model and intraparticle diffusion models. The kinetic results showed that the adsorption of aniline blue onto activated carbon well followed pseudo second-order model. Adsorption mechanism was evaluated in two steps, film diffusion and intraparticle diffusion, by intraparticle diffusion model. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy for adsorption process were estimated. Enthalpy change (48.49 kJ/mol) indicated that this adsorption process was physical adsorption and endothermic. Since Gibbs free energy decreased with increasing temperature, the adsorption reaction became more spontaneously with increasing temperature. The isosteric heat of adsorption indicated that there is interaction between the adsorbent and the adsorbate because the energy heterogeneity of the adsorbent surface.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1572-1577
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• 2003

High-power pulsed laser ablation under atmospheric pressure is studied utilizing numerical and experimental methods with emphasis on recondensation ratio, and the dynamics of the laser induced vapor flow. In the numerical calculation, the temperature pressure, density and vaporization flux on a solid substrate are first obtained by a heat-transfer computation code based on the enthalpy method, and then the plume dynamics is calculated by using a commercial CFD package. To confirm the computation results, the probe beam deflection technique was utilized for measuring the propagation of a laser induced shock wave. Discontinuities of properties and velocity over the Knudsen layer were investigated. Related with the analysis of the jump condition, the effect of the recondesation ratio on the plume dynamics was examined by comparing the pressure, density, and mass fraction of ablated aluminum vapor. To consider the effect of mass transfer between the ablation plume and air, unlike the most previous investigations, the equation of species conservation is simultaneously solved with the Euler equations. Therefore the numerical model computes not only the propagation of the shock front but also the distribution of the aluminum vapor. To our knowledge, this is the first work that employed a commercial CFD code in the calculation of pulsed ablation phenomena.

• Membrane and Water Treatment
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• v.5 no.4
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• pp.295-304
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• 2014

Adipic acid (hexane-1,6-dioic acid) is one of the most used chemical in industrial applications. This must be separated from any environmental contaminant. In this study, adipic acid separation from wastewater by adsorption method onto Perlite or Perlite + Mn or Perlite + Cu composites was investigated. Adsorption of Adipic acid was investigated in terms of equilibrium, and thermodynamic conditions. For thermodynamic investigations the experiments carried out at three different temperatures (298 K, 318 K, 328 K). In the equilibrium studies, 2 g of perlite and its composites were determined as the optimal adsorbent amount. Freundlich and Langmuir isotherms were applied to the experimental data. Freundlich isotherms for all temperatures used in this work gave some deviations with R square values under 0.98 where as Langmuir isotherm gave good results with R square values upper 0.99 at different temperatures. As a result of thermodynamic studies, adsorption enthalpy (${\Delta}H$), adsorption entropy (${\Delta}S$), and adsorption free energy (${\Delta}G$) have been calculated for each adsorbents.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.820-829
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• 2004

The In-Containment Refueling Water Storage Tank (IRWST), one of the design improvements applied to the APR -1400, has a function to condense the high enthalpy fluid discharged from the Reactor Coolant System (RCS). The condensation of discharged fluid by the tank water drives the tank temperature high and causes oscillatory condensation. Also if the tank cooling water temperature approaches the saturated state, the steam bubble may escape from the water uncondensed. These oscillatory condensation and bubble escape would burden the undue load to the tank structure, pressurize the tank, and degrade its intended function. For these reasons simple analytical modeling and experimental works were performed in order to predict exact tank temperature distribution and to find the effective cooling method to keep the tank temperature below the bubble escape limit (93.3$^{\circ}C$), which was experimentally proven by other researchers. Both the analytical model and experimental results show that the temperature distributions are horizontally stratified. Particularly, the hot liquid produced by the condensation around the sparger holes goes up straight like a thermal plume. Also, the momentum of the discharged fluid is not so strong to interrupt this horizontal thermal stratification significantly. Therefore the layout and shape of sparger is not so important as long as the location of the sparger hole is sufficiently close to the bottom of the tank. Finally, for the effective tank cooling it is recommended that the locations of the discharge and intake lines of the cooling system be cautiously selected considering the temperature distribution, the water level change, and the cooling effectiveness.

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.264-269
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• 2013

Purpose: This study was carried out to develop a classification index and grade levels to rate agricultural heaters for energy efficiency classification. Methods: The classification index was developed mainly by taking simplicity of calculation and easy access to relevant data into consideration. The grade levels were developed on the basis of a 5-grade classification system in which graded heaters are to be normally distributed over the grades. The value of each grade level were determined in terms of the classification index values calculated using the published performance data of agricultural heaters tested at the FACT in Korea over the past 12 years. Results: The thermal efficiency of agricultural heaters based on the enthalpy method was proposed as a reasonable classification index. The grade levels were proposed in equation form for three types of agricultural heaters: fossil fuel heaters, wood pellet heaters and wood pellet boilers. A reasonable energy efficiency classification of agricultural heaters could be performed using the proposed classification index and grade levels. Conclusions: It is expected that energy saving programs will be extended to agricultural machines in the near future. The classification index and grade levels to rate agricultural heaters for energy efficiency classification were developed and proposed for such near future to come.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.317-322
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• 2008

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchanger with R410A for Gas Engine Driven Heat Pump (GHP) application and to find optimum design conditions of indoor heat exchanger by parametric analysis for the key parameters. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant of R410A. The results show that fin pitch and longitudinal pitch have significant effect on the heat exchanger preformance. This study will provide the guideline for optimum design of indoor heat exchanger with R410A for GHP application.