• Food Engineering Progress
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• v.14 no.3
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• pp.193-201
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• 2010

The aim of this study was to analyse the quality of Yukwa puffed by using a vacuum puffing machine and compare to deep-fried Yukwa. The effect of vacuum puffing condition including heating temperature(100-${160^{\circ}C}$), preheating time(0-8 min) and vacuum puffing time(5-20 min) on physical and microstructure characteristics of the Yukwa was investigated. Vacuum puffed Yukwa at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 10 min puffing time had highest value in volumetric expansion ratio(10.04) and lowest value in bulk density(0.15 g/$cm^{3}$). The breaking strength showed the lowest value of 140 g/$cm^{3}$ in vacuum puffing Yukwa at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 15 min puffing time. The Yukwa puffed with the vacuum puffing machine at ${100^{\circ}C}$ heating temperature, 6 min preheating time and 15 min puffing time had the higher value of bulk density and the lower value of volumetric expansion ratio than those of deep-fried Yukwa. Increasing preheating time and vacuum puffing time caused an increase in white and an decrease in yellowness. The vacuum-puffed Yukwa exhibited smaller and uniform cell structure, while deep-fried Yukwa exhibited apparently in larger pores inside and smaller pores near the surface layer. The optimum condition of vacuum puffing machine for the production of vacuum-puffing Yukwa was ${120^{\circ}C}$ heating temperature, 4 min preheating time and 5 min puffing time.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.683-690
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• 2005

The microwave carbonization of rice chaff was performed, and their kinetics were compared to those of conventional thermal carbonization. Thermal carbonization was carried out at $300-600^{\circ}C$ for 30 minutes. The weight loss and C/H mole ratio remarkably increased as increase of temperature, while there was no carbonization by microwave dielectric heating in spite of increasing incident power and irradiation time. However, microwave carbonization was successfully performed by addition of 6 wt％ of thermal carbonized rice chaff, it's C/H mole ratio is larger than 3.0, as a catalytic initiator to uncarbonized rice chaff, and the kinetics was depended on the incident power and irradiation time, resulting in the coincide with thermal carbonization to the Arrhenius equation. The activation energy of microwave carbonization was quite low as compared to that of thermal carbonization, while the kinetic constant was large. This is due to the internal volumetric heating characteristics of carbonized rice chaff by microwave. The effect of ash, and C/H mole ratio and amount of carbonized rice chaff were investigated on microwave carbonization.

• KSBB Journal
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• v.23 no.4
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• pp.335-339
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• 2008

Biodiesel is an alternative and renewable energy source, which is hoped to reduce global dependence on petroleum and environmental problem. Biodiesel produced from a variety of oil sources such as vegetable oil, animal fat and waste oils, and has properties similar to those associated with petro-diesel, including cetane number, volumetric heating value, flash point, viscosity and so on. In this study, we investigate the effect of quality of raw materials on alkali-catalyzed transesterification for producing of biodiesel. The increase of content of free fatty acid and water in oil were caused the sharp decrease of conversion yield. Also, the low purity of methanol in reactant was inhibited the reaction rate. In the case of addition of sodium sulfate as absorbent to prepare catalyst solution, the content of fatty acid methyl ester in product was increased more about 1.6% than that of control. However, the addition of zeolite, sodium chloride and sodium sulfate as absorbent in reactant to remove water generated from reaction did not show any enhancement in the reaction yield. This result may provide useful information with regard to the choice and preparation of raw materials for more economic and efficient biodiesel production.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.673-679
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• 2001

The objective of this work is to estimate the temperature dependent thermal properties of the APC-2 composite using a inverse parameter estimation technique. The present inverse method features the estimation of the thermal conductivity and the volumetric heat capacity, which are dependent on the temperature inside the composite. Furthermore, the thermal conductivity is directionally dependent because of the aniosotropy of the composite. An on-line temperature measurement system with a suitable method of heating is built. A composite slab is fabricated using thermoplastic prepreg for the investigation. The corresponding computer code for evaluating the thermal properties inversely using the temperature reading transmitted from the measurement system is developed. The parameterized form is used for the rapid and stable estimation. The modified Newtons method is adopted for the solution technique of the inverse analysis. The estimated results are compared with the measured data from a previous study for the verification.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.91-99
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• 2009

This research were performed to evaluate co-incineration characteristics of sewage sludge and industrial waste in rotary kiln incinerator, and provide the fundamental data. Plastic portion (42.55%) in this industrial waste showed over 3 times higher than that (11.92%) of paper. Korean proximate analysis of the waste mixed with sewage sludge and industrial waste (3 : 7, volumetric basis) showed 16.3% of moisture, 70.5% of volatile solids, and 13.2% of ash, respectively. Low heating value of the mixed waste was 4,513kcal/kg. So it was thought that the mixed waste of sewage sludge and industrial waste (containing 43% of plastics and 12% papers) has enough heating value for co-incineration. The incineration of mixed waste showed the lowest SOx and NOx concentrations at $700^{\circ}C$. However, the operation at $950^{\circ}C$ was feasible in considering dioxin and the other hazardous gases. It was concluded that use of $Ca(OH)_2$ should be under investigation for the operation at $950^{\circ}C$.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.451-457
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• 2006

We synthesized phase pure CrN having surface areas up to $47m^2/g$ starting from $CrCl_{3}$ with $NH_{3}$. Thermal Gravimetric Analysis coupled with X-ray diffraction was carried out to identify solid state transition temperatures and the phase after each transition. In addition, the BET surface areas, pore size distributions, and crystalline diameters for the synthesized materials were analyzed. Space velocity influenced a little to the surface areas of the prepared materials, while heating rate did not. We believe it is due to the fast removal of reaction by-products from the system. Temperature programmed reduction results revealed that the CrN was hardly passivated by 1% $O_{2}$. Molecular nitrogen was detected from CrN at 700 and $950^{\circ}C$, which may be from lattice nitrogen. In temperature programmed oxidation with heating rate of 10 K/min in flowing air, oxidation started at or higher than $300^{\circ}C$ and resulting $Cr_{2}O_{3}$ phase was observed with XRD at around $800^{\circ}C$. However the oxidation was not completed even at $900^{\circ}C$. CrN catalysts were highly active for n-butane dehydrogenation reaction. Their activity is even higher than that of a commercial $Pt-Sn/Al_{2}O_{3}$ dehydrogenation catalyst in terms of volumetric reaction rate. However, CrN was not active in pyridine hydrodenitrogenation.

• Solar Energy
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• v.15 no.3
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• pp.3-14
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• 1995

The Direct Contact heat Exchanger(DCHX) has been widely studied in the chemical industry for many years due to its inherent simplicity as a counter-current divice for heat and mass transfer. In many solar systems, the DCHX unit can be combined with the thermal storage unit, or alternatively, it can be used separately from the storage unit, much like an external(to storage) closed heat exchanger system. In the present work, the spray column type of direct contact heat exchangers are studied extensively to harness the solar energy for hot water and spaced heating. Some of the major considerations that are involved in the design of heat exchangers in this study are that : working fluid is a hydrocaabon(such as Texaterm) or water which is either lighter or heavier than storage medium. The experimental data have revealed some interesting characteristics concerning the application of DCHXs for solar energy utilization. These experiments are carried out in the line of solar heating system, major results are as follows : 1) the flow and aspect of working fluid drop for maxium heat transfer 2) efficiency and volumetric heat transfer coefficient of D.C.H.X with a heavier working fluid are higher than those of D.C.H.X with a lighter working fluid.

• Atmosphere
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• v.24 no.4
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• pp.457-470
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• 2014

Thermodynamic conditions related with localized torrential rainfall in the middle west region of Korean peninsula are examined using radar rain rate and radiosonde observational data. Localized torrential rainfall events in this study are defined by three criteria base on 1) any one of Automated Synoptic Observing System (ASOS) hourly rainfall exceeds $30mmhr^{-1}$ around Osan, 2) the rain (> $1mmhr^{-1}$) area estimated from radar reflectivity is less than $20,000km^2$, and 3) the rain (> $10mmhr^{-1}$) cell is detected clearly and duration is short than 24 hr. As a result, 13 cases were selected during the summer season of 10 years (2004-13). It was found that the duration, the maximum rain area, and the maximum volumetric rain rate of convective cells (> $30mmhr^{-1}$) are less than 9hr, smaller than $1,000km^2$, and $15,000{\sim}60,000m^3s^{-1}$ in these cases. And a majority of cases shows the following thermodynamic characteristics: 1) Convective Available Potential Energy (CAPE) > $800Jkg^{-1}$, 2) Convective Inhibition (CIN) < $40Jkg^{-1}$, 3) Total Precipitable Water (TPW) ${\approx}$ 55 mm, and 4) Storm Relative Helicity (SRH) < $120m^2s^{-2}$. These cases mostly occurred in the afternoon. These thermodynamic conditions indicated that these cases were caused by strong atmospheric instability, lifting to overcome CIN, and sufficient moisture. The localized torrential rainfall occurred with deep moisture convection result from the instability caused by convective heating.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.199-207
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• 2015

Solid materials of ammonia sources with SCR have been considered for the application of lean NOx reduction in automobile industry, to overcome complex problems of liquid urea based SCR. These solid materials produce ammonia gas directly with proper heating and can be packaged by compact size, because of high volumetric ammonia density. Among ammonium salts and metal ammine chlorides, calcium ammine chloride was focused on this paper due to low decomposition temperature. In order to make calcium ammine chloride in lab-scale, simple reactor and glove box was designed and built with ammonium gas tank, regulator, and sensors. Basic test conditions of charging ammonia gas to anhydrous calcium chloride are chosen from equilibrium vapor pressure by Van't Hoff plot based on thermodynamic properties of materials. Synthetic method of calcium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%) from simple weight calculations which were confirmed by IC. Also, lab-made calcium ammine chloride were analyzed by TGA and DSC to clarify decomposition step in the equations of chemical reaction. To understand material characteristics for lab-made calcium ammine chloride, DA, XRD and FT-IR analysis were performed with published data of literature. From analytical results, water content in lab-made calcium ammine chloride can be discovered and new test procedures of water removal were proposed.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.545-551
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• 2007

HCl concentration, reaction temperature, and $Ti^{4+}$ concentration are the decisive factors in determining the structure of precipitates in the process of synthesis of $TiO_2$ particles from aqueous $TiCl_4$ solution by precipitation and the volumetric proportion of brookite phase in $TiO_2$ particles can be controlled by these factors. Pure brookite-type $TiO_2$ nanoparticles were synthesized by heating the aqueous $TiCl_4$ solution with no more than 1.0 M of $Ti^{4+}$, in which the concentration of HCl was kept in the range of about 2.53~6.41 M during reaction, at the temperature below $70^{\circ}C$ for 20 h. Also, Pure brookite was finally transformed to a rutile phase via an anatase phase through heat-treatment.