• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.85-90
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• 2017

The $TiCl_4$ as a blocking material is adsorbed in the mesoporous $TiO_2$ electron transfer layer(ETL) of the Perovskite solar cell to prevent the direct contact between the FTO electrode and the photoactive layer(AL), and facilitate the movement of the electrons between $TiO_2:TiCl_4$ ETL and Perovskite AL to improve the photoelectric conversion efficiency(PCE). The structure of the perovskite solar cell is FTO/$TiO_2:TiCl_4$/Perovskite($CH_3NH_3PbI_3$)/spiro-OMeTAD/Ag. It was investigated that the dipping time of the $TiO_2$ into $TiCl_4$ aqueous solution affects on the photoelectric characteristics of the device. By the dipping for 30 minutes, the PCE of the perovskite solar cell with the $TiO_2:TiCl_4$ ETL was the highest 10.46%, which is 27% higher than the cell with $TiO_2$ ETL. From SEM, EDS, and XRD characterization on the $TiO_2:TiCl_4$ ETL and the perovskite AL, it was measured that the decrease of the porosity of the $TiO_2$ layer, the detection of the Cl component by the $TiCl_4$ adsorption, the cube-type morphology of perovskite AL, and shift of the $PbI_2$ peak of the perovskite AL. From these results, it was confirmed that the $TiO_2:TiCl_4$ ETL and the perovskite AL were formed.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.121-135
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• 2012

Soil dispersion and heavy metal leaching with two heavy metal-contaminated soils were studied to derive the optimal dispersion condition in the course of developing the remedial technology using magnetic separation. The dispersion solutions of pyrophosphate, hexametaphosphate, orthophosphate and sodium dodecylsulfate (SDS) at 1 - 200 mM and the pH of solutions was adjusted to be 9 - 12 with NaOH. The clay content of suspension as an indicator of dispersion rate and the heavy metal concentration of the solution were tested at the different pHs and concentrations of the dispersion solution during the experiment. The dispersion rate increased with increasing the pH and dispersion agent concentration of the solution. The dispersion efficiency of the agents showed as follows: pyrophosphate > hexametaphosphate > SDS > orthophosphate. Arsenic leaching was sharply increased at 50 mM of phosphates and 100 mM of SDS. The adsorption of $OH^-$, phosphates and dodecysulfate on the surface of Fe- and Mn-oxides and soil organic matter and the broken edge of clay mineral might decrease the surface charge and might increase the repulsion force among soil particles. The competition between arsenic and $OH^-$, phosphates and dodecylsulfate for the adsorption site of soil particles might induce the arsenic leaching. The dispersion and heavy metal leaching data indicate that pH 11 and 10 mM pyrophosphate is the optimum dispersion solution for maximizing dispersion and minimizing heavy metal leaching.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.225-230
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• 2008

Objective of this study was to access the environmental impacts of the use of discharge water from municipal waste water treatment plant as alternative irrigation resources during drought season for rice cultivation. For the field experiments, it was observed that plant growth and yield characteristics at 20 days of alternative irrigation period with application of FAST (fertilizer application based on soil test) 50% were relatively the same as the control. For the surface water quality, it appeared that $EC_i$ (electrical conductivity of irrigation water) and SAR (sodium adsorption ratio) values of DMWT (discharge waters from municipal wastewater treatment plant) irrigation were twofold higher than those of ground water irrigation as the control regardless of fertilization levels. For the irrigation periods, there were not significantly difference between 10 and 20 days of treatments, but $EC_i$ and SAR values of surface water were highest at 30 days of irrigation periods at initial rice growing stages. Generally, $EC_i$ values of percolation water in all the treatments were gradually increasing until 30days after irrigation, and then decreasing to harvest stage. Overall, it might be considered that there was possibility to irrigate DMWT with application of FAST 50% for 20 days of drought periods at rice transplanting season. Furthermore, efficiency rate of alternative irrigation water for 20 days of drought period was 32.7% relative to the total annual irrigation water for rice cultivation.

• Journal of Life Science
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• v.22 no.5
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• pp.671-680
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• 2012

Three kinds of dietary composites-R+T, R+F, and R+TF-were combined in green tea (T), dietary fiber (F), and green tea dietary fiber mixture (TF) to red garlic extract (RG), respectively. The effects of their diets on anti-obesity were investigated $in$ $vitro$ and $in$ $vitro$ in obese rats induced high fat-cholesterol. In $in$ $vivo$ rats, the total phenolic content of the R+T and R+TF was 1.9~2.0 times higher, and their total cholesterol adsorption was 9.5~11.5 times higher than that of RG. $In$ $vivo$, male Sprague-Dawley rats were divided into 6 groups (Normal, HFC, HRG, HR+T, HR+F and HR+TF). Afterwards, the diets of the HRG, HR+T, HR+F, and HR+TF groups were supplemented with 1% of RG and its dietary composites (R+T, R+F, and R+TF) for 4 weeks, respectively. The final body weight of the HRG, HR+T, HR+F, and HR+TF groups decreased significantly compared to the group fed high fat-cholesterol (HFC), but the food efficiency ratio was not significantly different from the HFC group. The liver weight of the HFC group doubled compared to the normal group, whereas that of HR+T and HR+TF groups decreased significantly. The weight of visceral and epididymal fat decreased significantly in the groups fed the composites compared to the HFC group. The obesity index of HR+TF group decreased significantly only when compared to the HFC group. The serum lipid profile such as total lipids, cholesterol, triglyceride, LDL- and VLDL-cholesterol, as well as the atherogenic index and cardiac risk factors decreased drastically in all experimental groups compared to the HFC group, and the levels of HR+T, HR+F and HR+TF groups were a similar trend. GPT activity was not significantly different among the groups fed the composites, and it decreased significantly in the HRG group. The content of the lipid peroxide level decreased significantly in the HRG group and in the groups fed the composites, compared to the HFC group. Serum antioxidant activity was the highest in the HR+T group. We suggest that the hypolipidemic and anti-obesity effect of the RG composites, achieved by mixing green tea extract and/or dietary fiber, was due to their total phenolic content and total cholesterol adsorption effect.

• Journal of the Korean Chemical Society
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• v.51 no.1
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• pp.43-50
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• 2007

Liposomes having particle size from several tens to hundreds nanometers are efficient carriers for injectable drug delivery. Enhancement of liposome stability in bloodstream has been studied because of its relatively short circulation time and fast clearance from human body by reticuloendothelial system (RES) in blood vessel. In this study, new disaccharide-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) derivatives in which lactose or sucrose as the disaccharide molecule was conjugated covalently to DSPE were synthesized. Liposomes of which surface had disaccharide molecules were prepared by incorporating the disaccharide-DSPE into liposomes as one of their lipid components. Particle size of the prepared liposomes was approximately 100 nm. The liposomes of which surface were modified with the disaccharide-DSPE showed -25 mV of zeta potential value due to the presence of hydroxyl groups on their surface, while the unmodified control liposomes showed -10 mV of zeta potential value. Loading efficiency of model drug, doxorubicin, into liposomes was about 90%. Stability of the disaccharide-modified liposomes in vitro was evaluated by monitoring the amount of protein adsorption and particle size of the liposomes in serum. Disaccharide-modified liposomes were more stable in serum than unmodified control liposomes or polyethyleneglycol (PEG)-modified liposomes due to less adsorption of serum protein and hence less increase of their particle size. The liposomes of which surface was modified with disaccharide-DSPE conjugate can be used as long-circulating carriers for drugs having high toxicity or short half-life time due to their enhanced stability in blood circulatory system.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.341-347
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• 2008

The feasibility of commercializing the hydrothermal synthesis of Na-A type zeolite from siliceous mudstone has been conducted using a 50-liter bench-scale autoclave and the application of the zeolite as an environmental remediation agent. Siliceous mudstone, which is widely distributed around the Pohang area, was adopted as a precursor. The siliceous mudstone is favorable for the synthesis of zeolite because it contains 70.7% $SiO_2$ and 10.0% $Al_2O_3$, which are major ingredient of zeolite formation. The synthesis of zeolite was carried out under the following conditions that had been obtained from the previous laboratory-scale tests: 10hr reaction time, $80^{\circ}C$ reaction temperature, $Na_2O/SiO_2$ ratio = 0.6, $SiO_2/Al_2O_3$ ratio = 2.0 and $H_2O/Na_2O$ ratio= 98.6. The crystallinity and morphology of the zeolite formed were similar to those obtained from the laboratory-scale tests. The recovery and cation exchange ion capacity were 95% and 215 cmol/kg, respectively, which are slightly higher than those obtained in laboratory scale tests. To examine the feasibility of the zeolite as an environmental remediation agent, experiments for heavy metal adsorption to zeolite were conducted. Its removal efficiencies of heavy metals in simulated waste solutions decreased in the following sequences: Pb > Cd > Cu = Zn > Mn. In a solution of 1500 mg/L total impurity metals, the removal efficiencies for these impurity metals were near completion (> 99%) except for Mn whose efficiency was 98%. Therefore, the synthetic Na-A type zeolite was proven to be a strong absorbent effective for removing heavy metals.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.63-70
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• 2010

Transition metal based spent catalysts (Ni-Mo and Co-Mo), which were scrapped from the petrochemical industry, were reused for the removal processes of volatile organic compounds (VOCs). Especially the optimum regeneration procedures were determined using the removal efficiency of VOCs. In this work, the spent Ni-Mo and spent Co-Mo catalysts were pretreated with different physic-chemical treatment procedure: 1) acid aqueous solution, 2) alkali solution, 3) chemical agent and 4) steam. The various characterization methods of spent and its regenerated catalysts were performed using nitrogen adsorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS). It was found that all spent catalysts were found to be potentially applicable catalysts for catalytic oxidation of benzene. The experimental results also indicated that among the employed physico-chemical pretreatment methods, the oxalic acid aqueous (0.1 N, $C_2H_2O_4$) pretreatment appeared to be the most efficient in increasing the catalytic activity, although the catalytic activity of spent Ni-Mo and spent Co-Mo catalysts in the oxidation of benzene were greatly dependent on the pretreatment conditions. The pretreated spent catalysts at optimum condition could be also applied for removing other aromatic compounds (Toluene/Xylene).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.60-65
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• 2000

Biosorptions of Cr and Pb were evaluated for 23 species of marine algae collected from a Korean coast. Among a variety of species for biosorbent potential, Sargassum species showed higher uptake capacity for Cr and Pb. An adsorption equilibrium was reached in about 1 hr for Cr and 30 min for Pb. The maximum uptake capacity was136.0 mg Cr/g biomass and 232.5 mg Pb/g biomass, respectively. In Pb biosorption in the column packed with Sargassum tbunbertii, 300 and 200 bed Tolumes at the concentration of 50 mg/L in feed solution were processed at the column residence time of 5 and 10 min before the column breakthrough point occurred. The elutions with 0.1 M HCl solution were more than $95{\%}$. The high efficiency of continous biesorntion and elution (3 cycles) indicated that Sargassum thunbergii was an effective biosorbent for Pb recovery.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.9-17
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• 2006

Properties of wood charcoal made from the domestic wood species at $300-900^{\circ}C$ have investigated to understand the correlation between carbonization temperature and chemical and physical characteristics of wood charcoal. In terms of charcoal yield at particular carbonization temperatures, it was drastically decreased until the temperature reaches up to $600^{\circ}C$ and the decrease ratio of yield was reduced at higher temperatures. As the carbonization temperature increased, pH of the wood charcoal increased so that it became basic at last. The wood charcoal prepared at $600{\sim}700^{\circ}C$ showed the highest caloric value and those of wood charcoals made at higher temperature became plateau at a little lower level than the peak. The caloric value of Japanese larch charcoal was a bit higher than that of Red oak charcoal. The carbon content in the wood charcoal was increased as the carbonization temperature increased, whereas the hydrogen content was decreased. Specific surface area of the wood charcoal became larger with increase in temperature up to $600^{\circ}C$ but it was decreased or reduced in the increasing ratio after, and then it rose again at higher temperature than $800^{\circ}C$. Absorption capacity of the wood charcoal against iodine and gaseous acetic acid became greater as the carbonization temperature increased. Japanese larch charcoal presented higher absorption capacity than Red oak charcoal. As the above results, it is revealed that carbonization temperature affects the chemical and physical properties of wood charcoal. Therefore, to use wood charcoal with maximum effect it should be prepared at optimum temperature for proper use.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.657-661
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• 2009

Liquid microparticulated seaweed calcium was manufactured via a wet grinding process. Thereafter, different forming agents such as cyclodextrin, gum arabic, and Na-caseinate were added to the liquid calcium, which was then spray-dried to investigate the quality of the powdered calcium treatments. The moisture contents of samples were approximately 2%. It was also determined that the different kinds of forming agents did not affect the spray drying efficiency. In addition, calcium solubility was the highest in a solution of pH 2. In buffer solution and vinegar, the powdered calcium made with gum arabic showed the highest solubility among the treatments. The calcium contents of all the powdered microparticulate seaweed calcium samples were about 28%, and calcium content was not affected by the forming agents. The spray-dried calcium powder made by spray drying with gum arabic had the highest water vapor uptake, whereas the seaweed calcium was stable in terms of water adsorption. The results of SEM observations indicated that a portion of the spray-dried calcium powders were in nano-scale after wet-grinding. Among the treatments, the use of saccharides as a forming agent resulted in the most uniform particle distribution after spray-drying.