• Journal of the Korean Electrochemical Society
• /
• v.14 no.2
• /
• pp.98-103
• /
• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.2
• /
• pp.77-82
• /
• 2011

The surface of $Li[Ni_{0.35}Co_{0.3}Mn_{0.35}]O_2$ cathode was modified by $[Li,La]TiO_3$ coating using pH controlled coating solution. At low pH values (acidic solution), cathode powders, which is oxides, have a positive surface charge, whereas, they have a negative surface charge at high pH values. As a result, their charge could affect the formation of the coating layer on the surface of cathode powder. To determine the optimal pH value, the surface coating of the pristine powder was carried out at various pH values of the coating solution. The surface morphology of coated samples was characterization by SEM and TEM analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the pH of coating solution.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.2
• /
• pp.117-124
• /
• 2011

We demonstrate a new surface modification of high-voltage lithium cobalt oxide ($LiCoO_2$) cathode active materials for lithium-ion batteries. This approach is based on exploitation of a polarity-tuned gel polymer electrolyte (GPE) coating. Herein, two contrast polymers having different polarity are chosen: polyimide (PI) synthesized from thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid (as a polar GPE) and ethylene-vinyl acetate copolymer (EVA) containing 12 wt% vinyl acetate repeating unit (as a less polar GPE). The strong affinity of polyamic acid for $LiCoO_2$ allows the resulting PI coating layer to present a highly-continuous surface film of nanometer thickness. On the other hand, the less polar EVA coating layer is poorly deposited onto the $LiCoO_2$, resulting in a locally agglomerated morphology with relatively high thickness. Based on the characterization of GPE coating layers, their structural difference on the electrochemical performance and thermal stability of high-voltage (herein, 4.4 V) $LiCoO_2$ is thoroughly investigated. In comparison to the EVA coating layer, the PI coating layer is effective in preventing the direct exposure of $LiCoO_2$ to liquid electrolyte, which thus plays a viable role in improving the high-voltage cell performance and mitigating the interfacial exothermic reaction between the charged $LiCoO_2$ and liquid electrolytes.

• ALGAE
• /
• v.22 no.4
• /
• pp.253-259
• /
• 2007

This study deals with the taxonomy of the marine diatom Ditylum brightwellii (West) Grunow: shape, size and ratio, marginal ridge, labiate process, areolation, and seasonal distribution are all considered. Ditylum brightwellii were divided into two type; prism- and cylinder-shaped. Comparisons between specimens from the Yellow Sea were made on, (1) shape- prism types are prismatic-shaped and/or regular square or right-angled tetragon, cylinder types are cylinder-shaped and/or long right-angled tetragon in the girdle view, respectively; (2) size and ratiodiameters of prism types are 82.1 ± 2 μm, while those of cylinder types are 21.2 ± 5 μm and ratio of pervalvar axis/diameter- prism types cells are 1.0-1.5, but cylinder types are 3.9-5.5; (3) marginal ridges- prism types have dotted, while those of the cylinder-type cells have piece, slotted or fimbriated on the marginal ridge; (4) labiate process- both prism- and cylinder-types are central part in valve face, but length of labiate processes of prism types are longer than those of cylinder types; (5) cell margin- the girdle margin show many shallow furrows in prism type and smooth in cylinder type; (6) areolation- both prism- and cylinder-types are a radial pattern in the valve center, but areolae of prism types are larger than those of cylinder types; (7) seasonal distribution- cylinder types are dominated in summer and prism types in the other seasons.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.11
• /
• pp.1273-1281
• /
• 2014

Tissue engineering is an emerging research field that has the potential to restore, regenerate and repair damaged bone tissue and organs. Tricalcium phosphate and hydroxyapatite biomaterials-based calcium phosphate are excellent materials that have both osteoconduction and biocompatibility for bone tissue regeneration. In this study, solution structures were successfully fabricated using a fused deposition modeling system based on deposition and heating devices. The morphology characteristics of the bioceramic scaffolds sintered at a temperature of $1,300^{\circ}C$ were analyzed by scanning electron microscopy. The effects of various blended TCP/HA ratio on the microstructure and shrinkage were studied. The mechanical properties of the scaffolds were measured using a compression testing machine from stress-strain curves on the crosshead velocity of 1 mm/min. The fabricated scaffolds were evaluated by cell proliferation tests of MG-63 cells. The results of this study suggest that the blended TCP(75 wt%)/HA(25 wt%) scaffold is an appropriate scaffold for bone tissue regeneration.

• Applied Microscopy
• /
• v.39 no.2
• /
• pp.199-204
• /
• 2009

In this study, we observed the effects of repeated perms on the morphology of virgin hair of a healthy thirteen year-old girl with scanning electron microscopy. After the first treatment, the outer parts of cuticle cell were broken unevenly and roughly. Cuticle cells were lifted upward making a space. After the third treatment, cuticle cells were lifted off one another and the folded scales showed irregular surface areas. Broken pieces of cells were stuck on the surface and an empty hole was present in the endocuticle of the cytoplasm. We observed that cortex separated from cuticle layer more easilywith repeated treatments.

• Development and Reproduction
• /
• v.21 no.3
• /
• pp.287-295
• /
• 2017

This study was conducted to observe egg and larvae morphological development of carp to obtain basic data for resource conservation and taxonomic research. Brood carp used in the research (total length 67.3-75.5 cm, average $71.0{\pm}3.45cm$) were bred in a circular rearing aquarium ($600{\times}300{\times}100cm$) using a running water system from January to July, 2015. Breeding water temperature was maintained at $23.0-25.0^{\circ}C$(average $24.0^{\circ}C$). Fertilized carp eggs were translucent and globular, and their size was 1.75-1.89 mm (average $1.82{\pm}0.06mm$). Blastoderms formed 10 min after fertilization and reached the two-cell stage 30 min after fertilization. Then, the embryo turned dark and exhibited melanophores, and blood started flowing from the heart across the egg yolk at 42 hrs and 50 min after fertilization. Hatching began 70 hrs and 26 min after fertilization larvae emerged through the egg membrane, starting from the head. The length of prelarvae immediately after hatching was 5.23-5.38 mm (average $5.31{\pm}0.11mm$) the mouth and anus were closed, and the pectoral fin was formed. Postlarvae at 18 days after hatching had a total length of 11.9-13.9 mm (average $12.9{\pm}1.40mm$), separate anal fin and back membranes, and fin ray. Juveniles fish at 35 days after hatching had a total length of 29.9-30.2 mm (average $30.1{\pm}0.13mm$), with the body covered with scales, and the same number of fin rays, color, and shape as their broodstork.

• Applied Chemistry for Engineering
• /
• v.28 no.4
• /
• pp.383-396
• /
• 2017

The photothermal therapy is a method of cell ablation using the heat converted from the incident light by photothermal transducers. It offers a selective treatment to desired abnormal cells, in particular, tumor tissues. Among various photothermal agents, gold nanoparticles (Au NPs) have received enormous attention due to their unique physicochemical property over last two decades. In this review, we address research strategies and methods to improve treatment efficacy by organizing recent research works. We mainly focus on research works to enhance light-to-heat conversion via optimizing the morphology of Au NPs and related assemblies as well as the strategies to deliver Au NPs efficiently to specific targets. We also introduce convergence research efforts to combine Au NP-mediated photothermal treatment and other functions such as diagnostic capabilities and other therapeutic methods.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.16 no.2
• /
• pp.226-232
• /
• 2002

This study was carried out to investigate the effect of mixture of Gastrodiae rhizoma (GM) on blood amelioration in high cholesterol-diet rats. Sprague-Dawley male rats were randomly assigned to one normal diet and three high cholesterol-diet groups which contained 1 % (w/w) cholesterol diet. The groups of high cholesterol-diet were classified to control (high cholesterol-diet only), GM-1 (high cholesterol-diet and GM) and ST-1 (high cholesterol-diet and Statin drug). The body and organs weight were not significantly changed among the tested groups. Contents of serum total cholesterol and LDL-cholesterol were significantly increased in cholesterol-diet groups compared with normal diet group but significantly decreased in the group of GM-1. Morphology of red blood cell in GM-1 group was similar to normal diet group but the control group had many crystals of cholesterol. Hepatic xanthine oxidase activity in the rats of high cholesterol-diet was decreased up to the levels of normal diet group according to oral administration of GM. The results of the present study demonstrate that the orally injection of GM can ameliorate the status of total cholesterol and LDL-cholesterol, and repress xanthine oxidase in liver in high cholesterol-diet rats. These finding suggest that GM is expected to be an effective tea for the blood amelioration in high cholesterol-diet rats.

• Korean Journal of Materials Research
• /
• v.25 no.9
• /
• pp.480-486
• /
• 2015

$Pb_{1-x}MoO_4:Er^{3+}/Yb^{3+}$ phosphors with various doping concentrations of $Er^{3+}$ and $Yb^{3+}$ ($x=Er^{3+}+Yb^{3+}$, $Er^{3+}=0.05$, 0.1, 0.2, and $Yb^{3+}=0.2$, 0.45) are successfully synthesized using a microwave sol-gel method, and the up-conversion photoluminescence properties are investigated. Well-crystallized particles, which are formed after heat treatment at $900^{\circ}C$ for 16 h, exhibit a fine and homogeneous morphology with particle sizes of $2-5{\mu}m$. Under excitation at 980 nm, the $Pb_{0.7}MoO_4:Er_{0.1}Yb_{0.2}$ and $Pb_{0.5}MoO_4:Er_{0.05}Yb_{0.45}$ particles exhibit a strong 525 nm emission band, a weak 550 nm emission band in the green region, and a very weak 655 nm emission band in the red region. The Raman spectra of the doped particles indicate the presence of strong peaks at higher and lower frequencies induced by the disordered structures of $Pb_{1-x}MoO_4$ through the incorporation of the $Er^{3+}$ and $Yb^{3+}$ ions into the crystal lattice, which results in the unit cell shrinkage accompanying the new phase formation of the $MoO_{4-x}$ group.