• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.8
• /
• pp.1091-1097
• /
• 2002

Capacitated goat spermatozoa generated diacyl glycerol (DAG) when suspended in Krebs-Ringer bicarbonate medium and induced by progesterone or $Ca^{2+}$ ionophore A23187. We have added Sn-1-oleoyl-2-acetyl glycerol externally, to study the effect of DAG in goat sperm acrosomal exocytosis. Addition of neomycin abolished the DAG generating capacity of progesterone in a dose dependent manner, suggesting the involvement of a phosphoinositidase C activated phospholipase C system in the process. The level of increase in phosphatidic acid was considerably low and was produced well after the DAG generation thereby suggesting the involvement of a DAG kinase which phosphorylates DAG to produce PA. The inhibition of progesterone mediated effect by inhibitors of $GABA_A/Cl^{-}$ channel and $Ca^{2+}$ channels further supports the evidence that the events of binding of agonist to the receptor(s), opening of $Ca^{2+}$ channels and the activation of phospholipase C are reconciled to perform the function of acrosome reaction in capacitated goat spermatozoa.

• Journal of Surface Science and Engineering
• /
• v.33 no.5
• /
• pp.339-348
• /
• 2000

The study was conducted on the effect of bath composition on the surface appearance, the hardness and the crystal orientation of zinc electrodeposits from the chloride bath. (1) The hardness of the zinc electrodeposits from the chloride bath was increased by suppressing mass transfer of zinc through adding the organic additives and the chlorine ion in the electrolyte. (2) The surface whiteness of zinc deposits was decreased due to the change of the preferred orientation from (002) , (103) to (101) , (100) through increasing the organic additives and chlorine ion in the electrolyte. (3) The addition of Cu, Sn, Ni or Co in the chloride bath elevated the hardness of the zinc deposits but darkened the surface whiteness. (4) The optimum condition of the organic additives and the chlorine ion for increasing the hardness of zinc deposits and preventing dark surface ranges 0.3 m1/1 to 0.4 m1/1 and 6.5 mol/1 to 6.8mol/l respectively.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.12
• /
• pp.2263-2273
• /
• 2000

Catalytic wet air oxidation of acetic acid over Mn-Ce based catalysts deposited on various supports ($SiO_2$, $TiO_2$, $ZrO_2$), $ZrSiO_4$, $ZrO_2(10wt%)/TiO_2$) have been carried out in high pressure microreactors. Also, promotional effects by small addition(O.5~1.0 wt%) of p-type semiconductors (CoO, $Ag_2O$, SnO) have been investigated. From the screening tests for initial activity ranking, both Mn(2.8)-Ce(7.2 wt%) and Ru(O.4)Mn(2.7)-Ce(6.9 wt%) supported on $TiO_2$ were selected as the promising reference candidates. In $Mn-Ce/TiO_2$ reference catalyst, addition of small amount of each p-type semiconductor (Co, Sn and Ag) resulted in activity promotional effect and the degree of the increase was in the following order: Co> Ag > Sn. Especially, $Mn-Ce/TiO_2$ promoted with 0.5 wt% Co gave the 2.6 folds activity increase compared to the reference case attributing to the surface area increase as well as synergy effect. In $Ru-Mn-Ce/TiO_2$ reference catalyst, only Co(1.0 wt%) promoted case showed a little reaction rate increase.

• Korea Trade Review
• /
• v.47 no.4
• /
• pp.177-195
• /
• 2022

This study analyzed the volatility spillover effect between international non-ferrous metal futures markets using the BEKK-GARCH model. Statistical data are futures price data of copper (CU), aluminum (AL), nickel (NI), tin (SN) from Shanghai Futures Exchange (SHFE) and London Metal Exchange (LME) from April 1, 2015 to December 31, 2021. Combining the research results, first, in the case of copper, aluminum, and nickel, it was found that there was a two-way volatility spillover effect between the Shanghai and London markets, and the international influence of the London market was greater. Second, in the case of the tin, it was found that the Shanghai market has a volatility spillover effect on the London market from stage I, and it is strengthened in stage II. Third, in the case of nickel, it was found that there was a two-way volatility spillover effect in the first stage, but in the second stage, the London market had a unidirectional volatility spillover effect with respect to the Shanghai market. This study confirmed that China's influence in the international non-ferrous metal futures market is gradually increasing. In addition, it suggested that international investors can engage in arbitrage and hedging using China's non-ferrous metal futures market.

• Korean Journal of Materials Research
• /
• v.21 no.3
• /
• pp.161-167
• /
• 2011

The stress-strain responses and oxidation properties of cold-rolled Zr-1.5Nb-O and Zr-1.5Nb-O-S alloys were studied. The U.T.S. (ultimate tensile strength) of cold-rolled Zr-1.5Nb-O-S alloy with 160 ppm sulfur (765 MPa) were greater than that of Zr-1Nb-1Sn-0.1Fe alloy (750 MPa), achieving an excellent mechanical strength even after the elimination of Sn, an effective solution strengthening element. The addition of sulfur increased the strength at the expense of ductility. However, the ductile fracture behavior was observed both in Zr-Nb-O and Zr-Nb-O-S alloys. The beneficial effect of sulphur on the strengthening was observed in the cold rolled Zr-1.5Nb-O-S alloys. The activation volume of cold-rolled Zr-1.5Nb decreased with sulfur content in the temperature region of dynamic strain aging associated with oxygen atoms. Insensitivity of the activation volume to the dislocation density and the decrease of the activation volume at a higher temperature where the dynamic strain aging occurs support the suggestion linking the activation volume with the activated bulge of dislocations limited by segregation of oxygen and sulfur atoms. The addition of sulfur was also found to improve the oxidation resistance of Zr-Nb-O alloys.

• Corrosion Science and Technology
• /
• v.19 no.2
• /
• pp.100-107
• /
• 2020

The demand for powder-coated steel used in the marine industry is increasing owing to their superior corrosion resistance. However, the powder coatings used in commercial products can deteriorate easily by the penetration of brine. In an attempt to suppress brine penetration into the powder coating and significantly increase the corrosion resistance, three types of oxide particles were added to the coating. Electrochemical impedance spectroscopy tests in 3.5% NaCl solution were performed to evaluate the corrosion behaviors of the powder coating with oxide particles. The results showed that the addition of SiO₂ particles to a powder coating severely decreased the corrosion resistance due to the easy detachment of agglomerated SiO₂ particles with a coarse size from the coating layer. In contrast, the TiO₂ and SnO₂-added coatings showed better corrosion resistance, and the TiO₂-added coating performed best in the test conducted at room temperature. However, conflicting results were obtained from tests conducted at a higher temperature, which may be attributed to the effective suppression of brine penetration by the fine SnO₂ particles uniformly distributed in the coating.

• Journal of the Korean Ceramic Society
• /
• v.38 no.1
• /
• pp.100-105
• /
• 2001

An all solid-state thin film battery (TFB) was fabricated by growing, undoped and Pt-doped vanadium oxide cathode film ( $V_2$ $O_{5}$ ) on I $n_2$ $O_3$: Sn coated glass, respectively. Room temperature charge-discharge measurements based on Li/Lipon/ $V_2$ $O_{5}$ full-cell structure with a constant current clearly shows that the Pt-doped $V_2$ $O_{5}$ cathode film is superior, in terms of cyclibility. X-ray diffraction (XRD) results indicate that the Pt doping process induces a more random amorphous structure than an undoped $V_2$ $O_{5}$ film. In addition to its modified structure, the Pt-doped $V_2$ $O_{5}$ film has a smoother surface than the undoped sample. Compared to an undoped $V_2$ $O_{5}$ film, the Pt doped $V_2$ $O_{5}$ cathode film has a higher electron conductivity. We hypothesize that the addition of Pt alters electrochemical performance in a manner of making more random amorphous structure and gives an excess electron by replacing the $V^{+5}$. Possible mechanisms are discussed for the observed Pt doping effect on structural and electrochemical properties of vanadium oxide cathode films, which are grown on I $n_2$ $O_3$: Sn coated glass.

• Journal of Intelligence and Information Systems
• /
• v.17 no.4
• /
• pp.131-142
• /
• 2011

In recent years, Social Network Service, which is defined as a web-based service that allows an individual to construct a public or a semi-public profile within a bounded system, articulates a list of other users with whom they share connections, and traverses their list of connections. For example, Facebook and Twitter are the representative sites of Social Network Service, and these sites are the big issue in the world. A lot of people use Social Network Services to connect and maintain social relationship. Recently the users of Social Network Services have increased dramatically. Accordingly, many organizations become interested in Social Network Services as means of marketing, media, communication with their customers, and so on, because social network services can offer a variety of benefits to organizations such as companies and associations. In other words, organizations can use Social Network Services to respond rapidly to various user's behaviors because Social Network Services can make it possible to communicate between the users more easily and faster. And marketing cost of the Social Network Service is lower than that of existing tools such as broadcasts, news papers, and direct mails. In addition, Social network Services are growing in market place. So, the organizations such as companies and associations can acquire potential customers for the future. However, organizations uniformly communicate with users through Social Network Service without consideration of the characteristics of the networks although networks have different effects on information deliveries. For example, members' cohesion in an offline communication is higher than that in an online communication because the members of the offline communication are very close. that is, the network of the offline communication has a strong tie. Accordingly, information delivery is fast in the network of the offline communication. In this study, we compose two networks which have different characteristic of communication in Twitter. First network is constructed with data based on an offline communication such as friend, family, senior and junior in school. Second network is constructed with randomly selected data from users who want to associate with friends in online. Each network size is 250 people who divide with three groups. The first group is an ego which means a person in the center of the network. The second group is the ego's followers. The last group is composed of the ego's follower's followers. We compare the networks through social network analysis and follower's reaction analysis. We investigate density and centrality to analyze the characteristic of each network. And we analyze the follower's reactions such as replies and retweets to find differences of information delivery in each network. Our experiment results indicate that density and centrality of the offline communicationbased network are higher than those of the online-based network. Also the number of replies are larger than that of retweets in the offline communication-based network. On the other hand, the number of retweets are larger than that of replies in the online based network. We identified that the effect of information delivery in the offline communication-based network was different from those in the online communication-based network through experiments. So, you configure the appropriate network types considering the characteristics of the network if you want to use social network as an effective marketing tool.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.746-748
• /
• 2002

The effect of $MnO_2$ addition in $0.05Pb(Sn_{0.5}Sb_{0.5})O_3-0.8PbZrO_3-0.15PbTiO_3$(0.05PSS-0.8PZ-0.15PT) ceramics on crystal structure and electrical properties were studied. The sintering temperature and time were $1230^{\circ}C{\sim}1270^{\circ}C$ and 2hr, respectively. Then crystal structure, dielectric and pyroelectric properties were investigated. All the poled specimens showed the lower dielectric constant and $tan{\delta}$ than the unpoled specimens. Dielectric constant at 1kHz of the 0.05PSS-0.8PZ-0.15PT(MnO2 0.3wt%) system specimen sintered at $1250^{\circ}C$ for 2hr were 270 and showed the lowest $tan{\delta}$ of 0.2% after poling of $2kV_{DC}/mm$ at $150^{\circ}C$ for 30 minutes. Pyroelectric coefficient was maximum value of $50nC/cm^2K$ and Curie temperature was $224^{\circ}C$.

• Journal of Animal Science and Technology
• /
• v.47 no.4
• /
• pp.655-666
• /
• 2005

This study was performed to measure physicochemical and textural characteristics, and shelf-life effect of low-fat functional sausages(LFFSs) manufactured with sodium lactate(SL, 3.3%), lac pigment and various molecular weights(MWs) of chitosan (Low=1.5 kDa, Med=30-50 kDa and High=200 kDa) during storage at 15$^{\circ}C$ for 18 days. LFFSs had 73.7-76.0% moisture, lower than 3% fat and 14-15% protein, respectively. pH values were 6.05-6.44 and the control(150 ppm, $NaNO_2$) was the lowest among LFFSs (p<0.05). Increasing storage time decreased pH values, but no differences in pH values were observed up to 6 days of storage (p>0.05). LFFSs containing SL and low MW of chitosan improved water holding capacity (WHC) and different from those with SL and medium-MW chitosan. WHC was decreased with increased storage time and differences of WHC were observed from 18 days of storage. The addition of chitosan reduced both lightness and redness values, as compared to 150 ppm sodium nitrite(SN), and increased storage time decreased yellowness(p<0.05), especially at 12 days of storage. LFFSs with SL and medium-MW chitosan increased most textural properties compared to the control(p<0.05). The addition of SN of 150 ppm in LFFSs retarded microbial growth for E. coli 0157:H7, while those with SL tended to have an antimicrobial effect for Listeria monocytogenes(LM). The growth rate of LM was delayed by addition of various MW of chitosans in LFFSs, especially high MW chitosan, as compared to LFFSs containing SL alone. These results indicated that the functional, textural and antimicrobial effects of LFFSs were improved by addition SL and various MW of chitosan combinations. In addition, 0.05% lac pigment improved the cure color of LFFSs similar to those of 150 ppm SN.