• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.1 no.1
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• pp.73-79
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• 2003

In a pressurized water reactor, radioactive corrosion products (CRUD) in primary coolant system are one of the major sources for the occupational radiation exposure of the personnel in a nuclear power plant. Through the recent trend of long term fuel cycle in a nuclear power Plant, radioactive corrosion products deposited in reactor core for a long time are also the cause of Axial Offset Anomaly (AOA) having m effect on reactor power by the hideout of boron. CRUD consist primarily of magnetite, nickel ferrite, cobalt ferrite, and so on. They have the characteristic of strong magnetism. Therefore it is performed the conceptual design to develop the filter which removes the CRUD by magnetic field that is generated by an arrangement of permanent and electric magnets. Contrary to the conventional filter, the proposed filter does not interrupt the fluid flow, so there is little pressure drop and it can be used continuously. It is expected to be applied as one of the technologies for removal of the CRUB.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.11-18
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• 2006

[ $Co_3O_4$ ] particles with non-aggregation characteristics were prepared by various conditions such as preparation temperature, flow rate of carrier gas, and concentration of spray solution using spray pyrolysis. The morphology and crystallinity of the preformed particles obtained by spray pyrolysis at various conditions affected the mean size and morphology of the post-treated $Co_3O_4$ particles. The preformed particles with hollow and porous morphology obtained from spray solution with citric acid and ethylene glycol turned to $Co_3O_4$ particles with nano size, regular morphology and non-aggregation characteristics after post-treatment at $800^{\circ}C$. On the other hand, the preformed particles obtained by the preparation conditions of short residence time of particles inside hot wall reactor and high reactor temperature turned to $Co_3O_4$ particles with aggregated morphology after post-treatment. The mean crystallite size and particle size of the $Co_3O_4$ particles prepared from optimum preparation conditions were 47 nm and 210 nm at post-treatment temperature of $800^{\circ}C$.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.38-42
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• 2003

In a pressurized water reactor, radioactive corrosion products (CRUD) in primary coolant system are one of the major sources for the occupational radiation exposure of the personnel in a nuclear power plant. Through the recent trend of long term fuel cycle in a nuclear power plant, radioactive corrosion products deposited in reactor core for a long time are also the cause of Axial Offset Anomaly (AOA) having an effect on reactor power by the hideout of boron. CRUD consist primarily of magnetite, nickel ferrite, cobalt ferrite, and so on. They have the characteristic of strong magnetism. Therefore it is peformed the conceptual design to develop the filter which removes the CRUD by magnetic field that is generated by an arrangement of permanent and electric magnets. Contrary to the conventional filter, the proposed filter does not interrupt the fluid flow, so there is little pressure drop and it can be used continuously. It is expected to be applied as one of the technologies for removal of the CRUD.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.4
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• pp.246-252
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• 2000

Stellite 12 alloy-powder was overlaid on 410 stainless steel valve seat using plasma transferred arc(PTA) process. Variation of characteristic of microstructure and hardness of deposit with current(90~150 A) and preheat temperature(R.T.~$400^{\circ}C$) was investigated. Important conclusion obtained are as follows; All welding conditions used produced a sound deposit layer with no defect in single pass welding. The maximum deposit had 4.0~4.8 mm in thickness and its bead width was increased with increase of current and preheat temperature. The deposit showed hypoeutectic microstruture, which was consisting of primary cobalt dendrite and networked $M_7C_3$ type eutectic carbides. The amount of eutectic carbides was decreased and its dendritic secondary arm spacing was increased with increase of current. Hardness of the deposit was decreased with increase of current. Preheat temperature up to $400^{\circ}C$, however, showed little influence on the hardness and microstructure. The hardness was also influenced by diluted Fe content near the interface in addition to microstructure and dendritic secondary arm spacing. Hot hardness at $500^{\circ}C$ showed higher than 300 HV.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.171-177
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• 1993

In decontamination process to remove radioactive materials of reactor cooling system, the metal ions dissolved by organic acids in decontamination solution are separated by use of ion exchange resin in the column. However, organic acids in decontamination solution decrease the apparent affinity of the resin to metal ions. In light of this, some experiments were carried out on the Amberlite IRN-77 cation resin with cobalt and iron to gain a better understanding of the complexation effects on the ion exchange process. Experimental results showed that EDTA among organic acids used as chemical decontaminants predominantly caused reduction of ion exchange capacity of cobaltous ion to resin since this reagent formed the complex with the cobaltous ion stronger than that with the ferrous ion. In contrast, the effects of oxalic acid and citric acid were found to be negligible. And, single and two-component nonlinear equilibrium relationships of the metal ions were established using experimental data.

• Korean Journal of Food Science and Technology
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• v.9 no.3
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• pp.199-204
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• 1977

To improve the storage stability of Korean red pepper (Capsicum annuum), the equilibrium moisture content of the powder and effects of irradiation on the capsaicin, capsanthin and microorganisms were investigated during its storage. The equilibrium moisture contents of the powder at $25^{\circ}C$ and relative humidities of 43.7, 53.3, 64.4, 75.4 and 84.3% were 13, 18, 25, 28 and 37%, respectively, and the larger the particle size was, the lower the equilibrium moisture content was under the same storage conditions. Cobalt-60 gamma irradiation degraded partly the capsaicin in red pepper or in solution at dose levels above 500 krad, but did not affect the moisture and capsanthin contents during its storage. Total viable cell count of the powder was around $10^8$ per gram and $D_{10}$ value for the mixed organisms was 210 krad.

• Macromolecular Research
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• v.15 no.2
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• pp.95-99
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• 2007

The most recent developments in two areas: (a) synthesis of inorganic particles with control over size and shape by polymer additives, and (b) synthesis of inorganic-polymer hybrid materials by bulk polymerization of blends of monomers with nanosized crystals are reviewed. The precipitations of inorganics, such as zinc oxide or calcium carbonate, in presence and under the control of bishydrophilic block or comb copolymers, are relevant to the field of Biomineralization. The application of surface modified latex particles, used as controlling agents, and the formation of hybrid crystals in which the latex is embedded in otherwise perfect crystals, are discussed. The formation of nano sized spheres of amorphous calcium carbonate, stabilized by surfactant-like polymers, is also discussed. Another method for the preparation of nanosized inorganic functional particles is the controlled pyrolysis of metal salt complexes of poly(acrylic acid), as demonstrated by the syntheses of lithium cobalt oxide and zinc/magnesium oxide. Bulk polymerization of methyl methacrylate blends, with for example, nanosized zinc oxide, revealed that the mechanisms of tree radical polymerization respond to the presence of these particles. The termination by radical-radical interaction and the gel effect are suppressed in favor of degenerative transfer, resulting in a polymer with enhanced thermal stability. The optical properties of the resulting polymer-particle blends are addressed based on the basic discussion of the miscibility of polymers and nanosized particles.

• Korean Journal of Microbiology
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• v.6 no.2
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• pp.41-53
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• 1968

Studies on the carbohydrate metabolism of yeast as influenced by gamma-irradiation from cobalt-60 have been carried, then the mechanisms of radiation effect on respiration and fermentation were discussed under considerations of permeable changes of irradiated cell membrane. The cells of baker's yeast (Saccharomyces cerevisiae) which had been gamma-irradiated of 240 k.r. doses for an hour, then were put into aerobic oxidation and anaerobic fermentation without substrate. Total and fractionated carbohydrates of irradiated yeast cells were determined by calorimetric method with anthrone and orcinol reagents, the amounts of total carbohydrate, trehalose, RNA-ribose, PCA-soluble glycogen, alkali-soluble glycogen, acetic acid-soluble glycogen, mannan and glucan were determined according to the course of aerobic oxidation and anaerobic fermentation. It is found that the carbohydrates of irradiated cells leak out and amount of the losses teaches eleven times more than that of control, the volume of losses are seems to be replaced by water, it can be suggested the damage of gamma-irradiation occurs in the site of passive transport of cell membrane. The endogeneous aerobic respiration of irradiated cells are increased much more than control, the synthesis of reserve glycogen, glucan and RNA-ribose promoted much more than control. The anaerobic fermentation of irradiated cells are also increased than that of control, but the breakdown of carbohydrate is less than endogeneous respiration of irradiated cells. The synthetic rate is also less than that of aerobic oxidation. In irradiated yeast cells, trehalose is revealed to be primary substrate for endogeneous carbohydrate metabolism, so it is proved that the enzymic patterns are not changed but the activities of enzymes relating endogeneous respiration and autofermentation is activated. It is to be considerable to distiguish endogeneous respiration and autofermentation from exogeneous respiration and fermentation on irradiation, for membrane permeability changes and loses out carbohydrate by ionizing radiation.

• International Journal of Oral Biology
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• v.38 no.3
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• pp.111-119
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• 2013

Objective. To investigate the effects of the hypoxia inducible factor-1 (HIF-1) activation-mimicking agent cobalt chloride ($CoCl_2$) on the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and elucidate the underlying molecular mechanisms. Study design. The dose and exposure periods for $CoCl_2$ in hMSCs were optimized by cell viability assays. After confirmation of $CoCl_2$-induced HIF-$1{\alpha}$ and vascular endothelial growth factor expression in these cells by RT-PCR, the effects of temporary preconditioning with $CoCl_2$ on hMSC osteogenic differentiation were evaluated by RT-PCR analysis of osteogenic gene expression, an alkaline phosphatase (ALP) activity assay and by alizarin red S staining. Results. Variable $CoCl_2$ dosages (up to $500{\mu}M$) and exposure times (up to 7 days) on hMSC had little effect on hMSC survival. After $CoCl_2$ treatment of hMSCs at $100{\mu}M$ for 24 or 48 hours, followed by culture in osteogenic differentiating media, several osteogenic markers such as Runx-2, osteocalcin and osteopontin, bone sialoprotein mRNA expression level were found to be up-regulated. Moreover, ALP activity was increased in these treated cells in which an accelerated osteogenic capacity was also verified by alizarin red S staining. Conclusions. The osteogenic differentiation potential of hMSCs could be preserved and even enhanced by $CoCl_2$ treatment.

• Resources Recycling
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• v.16 no.6
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• pp.10-19
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• 2007

The mechanical process followed by hydrometallurgical treatment has been developed in order to recover cobalt and lithium from spent lithium ion battery. In the previous study, a citrate precursor combustion process to prepare cathodic active materials from the leaching solution was elucidated. Resynthesis of electrode materials should be more valuable in spent battery recycling. Conventional slurry mixing of $LiCoO_2$ and carbon cannot make uniform distribution, and therefore the cathode cannot reach the theoretical charge-discharge capacity and is easily degraded during the charge-discharge cycling. In this study, ultra-fine $LiCoO_2$ powders has been prepared by modification of the combustion process and fabricated the enhanced cathode by modification of mixing method of $LiCoO_2$ and carbon added.