• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.6
• /
• pp.1087-1094
• /
• 2010

We have developed a cylindrical multi-terminal capacitive-conductive sensor that could be attached to the internal surface of cooling system pipe to evaluate capacitance and conductivity of heat transfer fluid. It was used as measuring system to diagnose insulating condition, by which was kept a insulating resistance of inner stack and at the same time was cooled electrochemical heat of reaction of FCEV(fuel cell electric vehicle) stack that used a compressed hydrogen gas reacting with oxygen in accordance with variation on thermal degradation of nonconductive heat transfer fluid. Also to assess diagnosis characteristics of heat transfer fluid, i.e. coolant, we have performed accelerated aging test using developed sensor attached to cooling system. Consequently, it was measured dielectric and electric resistance of coolant to estimate and analyse for dielectric properties by degradation condition.

• Journal of Energy Engineering
• /
• v.26 no.2
• /
• pp.39-49
• /
• 2017

Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals, including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids. The waste water coming out of coffee industries has high concentration of organic pollutants and is very harmful for surrounding water bodies, human health and aquatic life if discharged directly into the surface waters. Hence it is essential to treat and manage the coffee waste. Oyster shells are a waste product from mariculture that creates a major disposal problem in coastal regions of southeast Korea. In the study, the oyster shell waste was used to treat the coffee waste and its effluents. Oyster shells are calcined at $1000^{\circ}C$ for 2 h, and allowed to test the calcined CaO powder ability to inhibit the growth of bacteria in different aging coffee wastes. Calcined oyster shell powder showed anti-bacterial effect that inhibited cell growth of Escherichia coli and other bacterial forms. The antimicrobial activity of calcium oxide from oyster shell waste for biological treatment and utilization as a fertilizers with economic ecofriendly in nature.

• Nuclear Engineering and Technology
• /
• v.41 no.8
• /
• pp.1127-1134
• /
• 2009

Concrete has three major properties after a penetration-reinforcing agent is applied on its surface. First, the durability is improved by the sol-gel process of synthesized material from the polycondensation of TEOS (tetra-ethoxyorthosilicate) and acrylate monomer. Second, the capability to absorb impact energy is reinforced through the formation of a soft and flexible layer of organic monomers by Tea (Tetra Ethyl Amin). Third, the capability to prevent deterioration is enhanced by adding isobutyl-orthosilicate and alcohol. The performance and application of an agent developed through the synthesis of organic and inorganic material in an effort to prevent concrete from deterioration and improve the durability of concrete structures were verified in diverse experiments. The results of these experiments showed that the application of the proposed penetration-reinforcing agent has the effect of increasing the compressive strength by filling up the internal pores of concrete with physically and chemically stable compounds after penetrating the concrete. It also improves the durability against the deterioration factors such as salt water damage, carbonation, freezing and thawing, and compound deterioration. Therefore, it is confirmed that the penetration-reinforcing agent is a useful substance for the management and repair of concrete structures.

• Journal of the Microelectronics and Packaging Society
• /
• v.18 no.4
• /
• pp.1-9
• /
• 2011

Understanding the void characterization in the solder joints has become more important because of the application of lead free solder materials and its reliability in electronic packaging technology. According to the JEDEC 217 standard, it describes void types formed in the solder joints, and divides into some categories depending on the void position and formation cause. Based on the previous papers and the standards related to the void, reliability of the BGA solder joints is determined by the size of void, as well as the location of void inside the BGA solder ball. Prior to reflow soldering process, OSP(organic surface preservative) finished Cu electrode was exposed under $85^{\circ}C$/60%RH(relative humidity) for 168 h. Voids induced by the exposure of $85^{\circ}C$/60%RH became larger and bigger with increasing aging times. The void position has more influence on mechanical strength property than the amount of void growth does.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2010.05a
• /
• pp.77-81
• /
• 2010

This study deals with the analysis of color-difference and physical property of anti-corrosion coatings using at inside of concrete tank for drinking water. Because anti-corrosion coatings are effected by chemical attack, color and physical property are changed. So in this study when epoxy resin coatings of 3 types were received chemical attack by Cl- and NaOH, we present the co-relationship between color-difference and bond strength. For this study, we used the colorimetry, which can measure the degree of color difference on surface of materials. As the results, in case of Cl-, color change is appeared, bond strength also is decreased. From this experiment, we could know that color change due to chemical aging has the deep relationship with physical performance(bond strength) materials. further researches are needed.

• Journal of the Korean Ceramic Society
• /
• v.31 no.12
• /
• pp.1501-1506
• /
• 1994

The precipitate of FeCl2.4H2O and NaOH, Fe(OH)2 was rapidly made to oxidize by H2O2 to prepare $\delta$-FeOOH. The particle size, surface and morphology of $\delta$-FeOOH, and the shape and structure of thermally decomposed $\delta$-FeOOH were investigated by the use of high resolution STEM. $\delta$-FeOOH prepared under the condition of reaction temperature of Fe(OH)2 at 4$0^{\circ}C$, [OH-][Fe2+]=5 and aging time of 2 hr Fe(OH)2, had 630$\AA$ mean particle size, 4~5 aspect ratio, 20.8 emu/g saturation magnetization and 210 Oe coercivity. The edges of $\delta$-FeOOH were inclined to (001) about 41$^{\circ}$, 60$^{\circ}$ and coincident with (102), (101) respectively. When $\delta$-FeOOH was thermally decomposed at 25$0^{\circ}C$ for 2 hr in vacuo, which had micropores of 0.9 nm thickness and crystallites of 2.4 nm thickness. (001)hex, [10]hex. of $\delta$-FeOOH parallel with (001)hex, [100]hex. of $\alpha$-Fe2O3 respectively. This showed three dimensional topotaxial structure transition, which was investigated by SADP (Selected Area Diffraction Pattern) of STEM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1159-1162
• /
• 2003

Recently we suffered lot of failures of polymer surge arresters made by same manufacture after one year field operation. In order to set up countermeasures we investigated the causes of failures. We extracted faulted arresters and sound ones which were installed in same pole with faulted ones for the electrical test and dissection. 44 arresters were removed from 8 branch offices. Almost all of faulted arresters hadtracking damage on the interface between inner module and housing and the surface of inner module was very rough and irregular. It was possible to occur moisture ingress into the interface between inner module and housing due to the void of the interface and non tight sealing caps. Lots of sound arresters were failed during the moisture ingress test. This result must relate with tracking damage of faulted arresters. Therefore we can say that arresters had poor interface and sealing system. But we could not found aging and defects of ZnO elements because the electrical performance except moisture ingress test of arresters showed good.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.246-249
• /
• 2000

The effects of Zr on the mechanical workability and tensile strength of Cu-Ni-Mn-Sn-Al alloys have been investigated and the following results were obtained. The mechanical workability of Cu-Ni-Mn-Sn-Al alloys are increased with addition of Zr. And the surface cracks of specimen were not produced in Zr added Alloys. Especially in condition of hot-worked beyond the 90% working ratio, Zr contained specimen showed intra-granule crack propagation but Zr-free specimen showed inter-granule mode. The tensile strength have maximum value in 0.05% Zr contained alloy. The aging mechanism of Cu-Ni-Mn-Sn-Al alloys were varied by Zr addition.

• Journal of the Korean Society for Heat Treatment
• /
• v.9 no.2
• /
• pp.103-111
• /
• 1996

In this paper, we studied on both electrochemical polarization behaviors and pitting characteristics of ultra high strength Al-Cu-Li-Mg-Ag-Zr alloys(named C1 and C2) and 2090 alloy according to their treatments in the deaerated 3.5% NaCl, using by the potentiodynamic and the potentiostatic method, SEM micrograph and surface roughness including depth of pitting attack. With the cyclic polarization curves, the hysteresis of the C1 and C2 alloys appeared more remarkably than that of the 2090 alloy, because of precipitation microstructural difference between C1, C2 alloys and 2090 alloy. In the pitting experiments, the correlations between pitting growth and aging conditions were analyzed with the SEM micrograph and measurement of the pit depth.

• Journal of Veterinary Clinics
• /
• v.14 no.1
• /
• pp.30-36
• /
• 1997

It is well estabilished that IL-4, IL-6, $IFN{\gamma}$ and immunoglobulin production are increased as a consequence of advancing age, and endothelial cells increase their expression of pro-inflammatory surface protein, such as ICAM-1, as a consequence of contact with inflammatory cytokines, including IL-1, $TNF{\alpha} or INF{\gamma}.$ This study was designed to define the relationship between age-associated changes of cytokines and immunoglobulin production and ICAM-1 expression in aged mice. Serum from aged mice had elevated IL-6 and immunoglobulin levels compared to mature adult controls and activation-induced production of $IFN{\gamma}$ of splenocytes from aged mice were increased above normal adult level. By immunoperoxidase staining, ICAM-1 in hearts of normal adult mice was expressed occasionally at low levels, but in aged mice, the number of positive blood vessels for ICAM-1 were increased and also the immunoreactivity were stronger. Therefore, these finding indicate that the altered expression of ICAM-1 eith normal aging may actually be correlative to these age-related changes in cytokiness and immunoglobulin production.