• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2006년도 하계학술발표대회 논문집
• /
• pp.215-220
• /
• 2006

Along with socioeconomic development and improving standard of living, the heat demand for heating and cooling in residential and commercial sectors is expected to expand rapidly, reaching over 43 million TOE by 2010 in Korea(about 80% increase compared with that in 1995). Since most of this heat demand is loop temperature below $60^{\circ}C$, the utilization of 'unused energy' is surely one of very effective measures to both environmental preservation and energy conservation. 'Unused energy' in this paper is implicated as 'temperature differential energy' available from treated sewage water, useful and abundant heat source for heat pump(cooler in summer and warmer in winter than outside air). An analysis was carried out to estimate the energy potential of treated sewage water for heat pump heat source. Some analysis were taken to study the characteristics of a heat pump system using the treated sewage water as heat source.

• 한국세라믹학회지
• /
• 제40권7호
• /
• pp.696-701
• /
• 2003

교반형 볼 밀에서 실리카 분말의 열처리에 따른 분쇄효율을 분쇄에 따른 에너지 소비량을 측정함으로써 조사하였다. 열처리를 행한 것과 행하지 않은 시료를 비교해 보면, 600~90$0^{\circ}C$에서 열처리 후 실온에서 냉각된 시료를 건식 분쇄하였을 경우 약 40~50% 정도, 열처리 후 물속에서 급속 냉각한 경우 약 52～62% 정도의 에너지의 감소 효과가 있었다. 또한 열처리한 실리카 분말을 습식 분쇄를 할 경우 건식 분쇄에 비하여 약 40% 정도의 분쇄에너지가 적게 소모되고 있음을 알 수 있었다. 또한 실리카 분말을 열처리 한 후, 급속 냉각할 경우 발생하는 열충격은 입도에 대한 영향을 거의 받지 않으며 분쇄효과를 향상시킴을 알 수 있었다.

• Journal of Magnetics
• /
• 제19권2호
• /
• pp.106-110
• /
• 2014

$Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ HDDR-treated powder was compacted by hot-pressing using different configurations of dies and heating rates. The die configurations were especially different in terms of the evacuation system that was used in heating for hot-pressing. The coercivity in the compacts was influenced by the evacuation system of the die and heating rate. In spite of the identical hot-pressing temperature and heating rate, coercivity was radically reduced above $600^{\circ}C$ in the compacts prepared in the closed-type die compared to that in the compacts prepared in the open-type die. The coercivity in the compacts prepared in the closed-type die decreased with increasing heating rate and the value further increased when extreme high heating rate was employed. $Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ HDDR-treated powder contained a significant amount of residual hydrogen (approx. 1500 ppm) in the form of $Nd_2Fe_{14}BH_x$ hydride. The dramatic coercivity decrease in the compact prepared in the closed die is attributed to the disproportionation of $Nd_2Fe_{14}BH_x$ hydride. High coercivity is mainly due to the effective desorption of hydrogen or the suppression of hydrogen-related disproportionation upon hot-pressing.

• 한국식품영양학회지
• /
• 제28권1호
• /
• pp.126-133
• /
• 2015

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch's thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. This result is appeared equally at wheat, corn and sweet potato starch. At this study, we treated potato, wheat, corn and sweet potato starch by ohmic/conventional method and observed change of external structure by microscope and internal structure by X-ray diffractometer. Conventional heated at $55^{\circ}C$ potato starch was not external structural changes. But ohmic heated potato starch is showed largely change. Some small size starch particle were broken or small particles are made of larger particle together or small particles caught up in the large particle. Changes in ohmic heated potato starch at $60^{\circ}C$ was greater. The inner matter came to an external particle burst inside and only the husk has been observed. The same change was observed in the rest of the starch. The change of internal structure of potato starch was measured using X-ray diffraction patterns. There was no significant difference between ohmic and conventional heating at $55^{\circ}C$. But almost every peak has disappeared ohmic at $60^{\circ}C$. Especially $5.4^{\circ}$ peak to represent the type B was completely gone. When viewed from the above results, external changes with change in the internal crystal structure of the starch particles were largely unknown to appear. In conclusion, during ohmic heating changes of starch due to the electric field with a change in temperature by the heating was found to have progressed at the same time.

• 동력기계공학회지
• /
• 제17권3호
• /
• pp.28-34
• /
• 2013

This study is experimentally performed for using the oyster shell as a desiccant in the fluidized bed with bundle of heating pipe. The test material is oyster shell from fishery wastes which can use without costs. The main parameters of experiment are inlet air temperature, velocity of inlet air and heat flux of heating pipes. Also the geometry of heating pipe is treated as important parameter. From this study, the effect of inlet air temperature and input heat flux have much affect to increase the heat and mass transfer. On the other hand, the effect of inlet air velocity has less affect to increase the heat and mass transfer. And it is clarified that the oyster shell has sufficient probability for using as a desiccant in air-conditioning system.

• Journal of Biosystems Engineering
• /
• 제38권3호
• /
• pp.180-184
• /
• 2013

Purpose: This study explored the factors influencing heating value in the process of torrefaction of water hyacinth. Methods: Torrefaction was applied with three temperature settings (200, 300, $400^{\circ}C$) and three time settings (1, 2, 3 h) using small electric heaters (11.3L of holding volume). This study investigated the heating values with the washing process and process factors influenced the torrefaction. In addition, this study compared the heating values in washed and unwashed samples and suggested the optimal conditions for increasing heating value. Results: Torrefaction increased the heating value by 8.18 ~ 30.04%. Comparing heating values of each condition, the optimal temperature for torrefaction was $300^{\circ}C$ and holding time was 1 hour. The washing process increased the heating value by 19 ~ 27%. The heating value of the sample treated at $300^{\circ}C$ for three hours was 4310.80 kcal/kg, which was greater than the first class wood pellet of 4300 kcal/kg. Conclusions: This study proved that the torrefaction and washing process increased the heating value of water hyacinth. Therefore, water hyacinth is expected to be an eco-friendly biomass which substitutes for wood pellet.

• 한국세라믹학회지
• /
• 제28권1호
• /
• pp.29-36
• /
• 1991

Microporous glasses in the system TiO2-SiO2-Al2O3-B2O3-CaO-Na2O were prepared by the phase-separation technique. Morphology and distribution of pore and specific surface area of glasses heated and leached out at various conditions were investigated by SEM and Porosimeter. Crystallization of glasses heated above transition temperature was also inspected by X-ray diffraction method. When the heating temperature and time increased, the pore size and volume increased, but the specific surface area decreased above the critical temperature. The phase-separation, specific surface area and pore size showed more sensitive change on the variation of heating temperature than of heating time. The specific surface area and micropore volume of porous glasses prepared in this study were about 120-330$m^2$/g and 0.001-0.01cc/g, respectively. Mean pore size of porous glasses were about 20-90$\AA$. Anatase phases was deposited when the parent glass was heat-treated at 75$0^{\circ}C$ for 6hrs.

• 한국산업융합학회 논문집
• /
• 제3권4호
• /
• pp.345-351
• /
• 2000

The change of crystalline structure of drawn PP filaments were investigated. Samples were treated by isothermally annealed after elevated heating from $20^{\circ}C$. Measurements were carried out with XRD for crystallite size and density gradient tube for crystallinity. Isothermally heat treatment were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. in dry oven. The isothermal heat treatment after elevated heating from $20^{\circ}C$ were carried out at the temperature of $100^{\circ}C$, $120^{\circ}C$ and $140^{\circ}C$ for 10min., 30min. and 60min. with heating rate of $1^{\circ}C$/min., $5^{\circ}C$/min. and $10^{\circ}C$/min. From the results of this study, it found the following facts. It was found that the crystallinity and crystallite size of (110) plane of sample were increased with increasing of annealed temperature and time. Also crystallinity and crystallite size of samples which were isothermally annealed after elevated heating from $20^{\circ}C$ were higher than those of isohtermally annealed samples.

• 한국의류학회지
• /
• 제19권1호
• /
• pp.36-50
• /
• 1995

The purpose of this study was 1) to estimate the improvement of thermal storage/release and moisture transport properties of PEG-treated acrylic athletic socks and suggest the optimum add-on for PEG treatment, 2) to investigate wear performance of untreated cocks and two kinds of socks treated with PEG of minimum and optimum add-on respectively, and 3) to consider the effect of thermal storage/release and moisture transport properties of PEG- treated socks on the wear performance and the subjective comfort zone. Thermal activities of specimens treated by PDC were evaluated on a DSC by measuring the heat of fusion on heating and the heat of crystallization on cooling. Moisture regain, absorption speed, wickability, water retenti on value, and water-vapor permeability were measured. In the wear trials that the subjects performed a subsequent exercise protocol wearing three differently treated socks in a conditioned environment ($14\pm2^{\circ}C$, 65$\pm$2% R.H.), microclimate temperature and humidity, and subjective wear sensations including thermal sensation, wettedness, softness, fit, and overall comfort were obtained. PEC-treated specimens with more than 20% add-on showed thermal storage on heating and thermal release on cooling by a DSC and the heat contents of treated ones were generally proportional to the add-ons. Moisture transport properties were highly improved after PEG treatment and increased rapidly with increasing add-on. The tendencies were, however, relaxed above 50% add-on and the treated knits were much stiffer above that add-on. In the wear trials of untreated, PEG add-on 20%, and 50% acrylic socks, the changes of microclimate temperature of 50% socks were significantly less than that of 20% socks. PEG add-on 50% socks showed significantly less changes of microclimate humidity than other two kinds of socks. Three kinds of socks showed significant differences in overall comfort and add-on 50% socks were accepted more comfortable than other two kinds of socks. Comfort zone of foot was extended after PEG treatment on socks and it implied that the subjects wearing PEG- treated socks felt comfortable in wider ranges of microclimate temperature and humidity.

• 열처리공학회지
• /
• 제26권1호
• /
• pp.7-13
• /
• 2013

Vacuum heat treatment(indirect heating method) has long exposure time at high temperature and low quenching rate. Contrarily salt bath heat treatment (direct heating method) has short exposure time at high temperature and fast cooling rate. With these different features of processes, mechanical properties such as hardness, tensile strength and impact strength of products show very different results. In this study, Salt bath heat treated products showed higher tensile strength and impact strength than vacuum heat treated products but hardness was not much different. These lower mechanical properties of vacuum heat treated products are due to differences in heat process and secondary hardening with high temperature tempering process. Consequently, It indicates that salt bath heat treatment is better way than vacuum heat treatment for product to have high mechanical properties.