• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.50-56
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• 2016

Spherical lithium manganese oxide spinel, $Li_{1.10}Mn_{1.86}Al_{0.02}Mg_{0.02}O_4$ was prepared by wet-milling, spray-drying, and sintering process. In the spray-drying process, solid content in slurry was varied from 20 to 30 wt%. In the sintering process, the precursors have been sintered under air or $O_2$ atmosphere. While the as-prepared samples exhibit excellent electrochemical properties at room temperature, the discharge voltage profiles at 5.0C are very different one from another. The origin for the difference especially at initial state of discharge is oxygen defect. The sample prepared in air has larger capacity related to the plateau at 3.3 V (vs. $Li/Li^+$) which is caused by the oxygen defects than the one prepared in $O_2$. The difference of discharge voltage profiles especially at the final state of discharge comes from different diffusion rate of $Li^+$ ions. The sample prepared from 30 wt% solid content of slurry shows twice higher diffusion rate than the samples prepared from 20 wt% solid content, which is attributed to better compactness between primary particles for the sample prepared from 30wt % solid content than the one prepared by 20 wt%.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.41-52
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• 2014

Decomposed granite soil is likely to lose its strength when exposed to air or water. Such a geomaterial is weathered by wetting-drying or freezing-melting. In this study, resonant column tests were conducted to figure out the dynamic characteristics of granite soil that has affected by environmental changes like weathering condition. The results show that wetting-drying weathering condition is the most affective parameter on the dynamic characteristics of granite soil. In the meantime, artificial weathering conditions such as freezing-melting has less affection at first and getting increase as the process repeats constantly.

• Journal of the Korean Ceramic Society
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• v.38 no.4
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• pp.307-307
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• 2001

Combustion process with citrate was used to produce the LiMn$_2$O$_4$powder. Precursors are pre-ignited in open air followed by post-heating in the range from $600^{\circ}C$ to 80$0^{\circ}C$ for 4h. With varying the molar ratio (R) of ethylene glycol (EG) to citric acid (CA) from 0 to 4, the effect of EG content on powder characteristics is evaluated. Vacuum drying promote the auto-ignition at room temperature. With small addition of EG metal ion was selectively segregated with organic substances and undesired lithium evaporation occurred during post-heating. LiMn$_2$O$_4$phase which is produced by combustion reaction was decomposed back to Mn$_3$O$_4$because the reaction temperature was higher than 95$0^{\circ}C$. With increasing EG content, the homogeneity of LiMn$_2$O$_4$powder increased and specific surface area increased. And lithium evaporation during vacuum drying and/or ignition also increased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.1 s.113
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• pp.1-8
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• 2006

To overcome troubles in strength and process of linerboard caused by raw materials, a neutral sizing which is usual in fine paper making can be considered. A new sizing agent is necessary to show good performance in a system with high conductivity and COD. In this study, fast cure type AKD was examined as a new sizing agent and compared with conventional AKD. The effects of fixing agent addition and drying condition were also investigated. Fast cure type AKD which has a higher cationicity showed better sizing degree than conventional AKD in spite of low addition level and no curing treatment. And when fixing agent of sufficient amount was added, sizing degree was improved for both AKDs. High cationicity is a crucial factor for neutral sizing of linerboard for obtaining fast and stable sizing degree. Drying with temperature over $100^{\circ}$ was desirable for developing sizing degree.

• Environmental Analysis Health and Toxicology
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• v.14 no.3
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• pp.75-79
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• 1999

Due to increasing marine pollution there is a great possibility that seaweed is contaminated with polycyclic aromatic hydrocarbons (PAHs). To investigate the effect of processing on PAM removal from Porphyra tenera (laver) contaminated PAH, laver was contaminated with fluoranthene known to have a strong photoinduced toxicity, followed by washings and drying, which are usual processes for dried laver preparation. Sample at each step was collected and its toxicity was evaluated using cultured animal cells as well as analyzing PAH contents. Fluoranthene level in laver was significantly lowered by sequential washings with sea water and distilled water, but not by drying. Fluoranthene content in raw laver right after contamination was 221 ppm and decreased to 130 ppm by washings with seawater plus distilled water while its level was not lurker lowered by drying process. Cytotoxicity and photoinduced cytotoxicity in mammalian cells were significantly elevated in laver extracts containing fluoranthene. Cellular arylhydrocarbon hydroxylase (AHH), one of the biomarkers for cellular accumulation of PAH, was greatly induced by laver extract contaminated with fluoranthene. These results suggest that photoinduced toxicity and AHH activity can be used to monitor contamination of seafood by PAHs. Fluoranthene accumulated in laver was efficiently removed by sequential washings with seawater and tap water for 24 hrs and 12 hrs, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.226-231
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• 2005

To investigate the physical properties of sea tangle (Laminaria japonica) alginates, extracted by the Mexican process, the effects of extracting time and drying methods on intrinsic viscosities, MWs and DPs of alginates were examined. The MWs of alginates before and after dialysis decreased with increase of extracting time. The MW s before dialysis were lower than those after dialysis. The ash contents before dialysis decreased with increase of extracting time. After dialysis the ash contents of the alginates showed 10.4-10.9% of those, which were little affected by extracting time. In the ash composition after dialysis, the sodium content was 4.4 g/100 g, $90\%$ of total ash content. The ash contents, the intrinsic viscosities, the average molecular weight and the DPs of the alginates dried by AD before dialysis were higher than those by VF. The ash and uronic acid contents of alginates after dialysis showed $10.6-10.9\%\;and\l88.1-88.9\%$, respectively. But the intrinsic viscosities, the MWs and DPs of the alginates after dialysis gradually decreased by following dry methods. The decreased order was ADAD, ADVF, VFAD, VFVF. The coefficient of determination between MWs and DPs in the alginates having more than 300 kDa was 0.999.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.330-335
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• 2009

The principal objective of this study was to investigate changes in ice dendrite size during the freezing of tuna, in order to formulate a mathematical model of ice dendrite size. The tuna was frozen via a uni-directional heat transfer. Thermogram analysis allowed us to determine the position of the freezing front versus time, which is referred to as the freezing front rate. The morphology of the ice dendrites was assessed via scanning electron microscopy after freeze-drying, and the retained pore size was measured as ice dendrites. We noted that the mean size of ice dendrites increased with the distance to the cooling plate; however, it decreased with reductions in the cooling rate and the cooling temperature. In addition, shorter durations of the freeze-drying process decreased the freezing front rate, resulting in a larger size of the ice dendrite pores that operate as water vapor sublimation channels. According to our results, we could derive a linear regression as an empirical mathematical model equation between the ice dendrite size and the inverse of the freezing front rate.

• Clean Technology
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• v.12 no.4
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• pp.217-223
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• 2006

The operating variables of a desorption step were experimentally investigated tor the cycle of the process made up of benzene adsorption, steam desorption, and drying step. The effect of adsorbent regeneration depending on existence and nonexistence of drying step was studied by breakthrough curves obtained in the adsorption step of the second cycle. The duration of drying step was determined by the experimental results. In case that the amount of nitrogen gas was fixed, the regeneration efficiency increased with the amount of steam. However, the effect of steam decreased as the amount of nitrogen increased. Therefore, it would be possible to predict the optimum amount of steam comparing the amount of nitrogen gas with amount of steam in economic view.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.449-457
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• 1996

The main purpose of this study was to investigate sulfur dioxide removal performance of flue gas desulfurization system utilizing a Spray Absorption/Drying Reactor. In this system, the size of droplets was considered the most significant factor and tested using a PDA system. Lime slurry flow rate, operating temperature, calcium/sulfur (Ca/S) ratio and applied air pressure were selected as major operation variables and tested/analyzed in terms of system performance. The results are as follows. 1. The $SO_2$ removal efficiencies were 49%, 74%, 85% for Ca$(OH)_2$ slurry flow rate of 10, 20, 30 ml/min, which implies that the increase of slurry flow rate improves removal efficiency. The optimum slurry flow rate in this study was, however, considered 20 ml/min because of constraints of system troubles and absorbent utilization. 2. As Ca/S ratio increased, $SO_2$ removal efficiency was observed to increase. 3. As air pressure, at the atomizing nozzole, increased from 3 to 5 $kg/cm^2, SO_2$ removal efficiency increased from 74% to 80%, because of droplet size reduction due to pressure increase during atomizing process and the increase of surface area, helping mass transfer between gas and liquid phase.

• Journal of Powder Materials
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• v.27 no.3
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• pp.198-202
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• 2020

The effect of sublimable vehicles on the pore structure of Cu fabricated by freeze drying is investigated. The 5 vol% CuO-dispersed slurries with camphene and various camphor-naphthalene compositions are frozen in a Teflon mold at -25℃, followed by sublimation at room temperature. After hydrogen reduction at 300℃ and sintering at 600 ℃, the green bodies of CuO are completely converted to Cu with various pore structures. The sintered samples prepared using CuO/camphene slurries show large pores that are aligned parallel to the sublimable vehicle growth direction. In addition, a dense microstructure is observed in the bottom section of the specimen where the solidification heat was released, owing to the difference in the solidification behavior of the camphene crystals. The porous Cu shows different pore structures, such as dendritic, rod-like, and plate shaped, depending on the composition of the camphornaphthalene system. The change in pore structure is explained by the crystal growth behavior of primary camphor and eutectic and primary naphthalene.