• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.1-5
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• 2004

Al-brass is the raw material of mnufacturing tubes for heat exchanger of vessel where seawater is used to coolant because it has high level of heat coductivity and excellent mechanical properties and high level of corrosion resistance due to cuprous oxide($Cu_2O$) layer against seawater. However, damage of Al-brass tubes for heat exchanger of vessel is reported that local corrosion such as stress corrosion cracking occurred by synergism effect between mechanical factor and corrosion environment. In this study, to investigate on the effect of stress on the polarization characteristics of Al-brass. At the stress of 0% and 95% yield strength by constant displacement tester, in 3.5% NaCl + 0.1% $NH_4OH$ solution, the polarization tests were carried out. And thus open circuit potential, corrosion current density, anodic polarization, cyclic polarization and dezincification behavior of Al-brass are investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.12 s.105
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• pp.1347-1354
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• 2005

The free vibration characteristics of Al cantilever square plates with a brass inclusion were analyzed experimentally and numerically The experimentally obtained natural frequencies and mode shapes were compared with the FEM analysis results. The impulse exciting method was used for experiment and ANSYS software package was used for FEM analysis. The natural frequencies obtained iron experiment and numerical analysis matched within $0\%$. It was found that the natural frequencies of the Al cantilever square plates with a brass inclusion decrease as the size of inclusion increases. For the third mode shape, comparing the nodal line of the Al plate and the Al plate with a inclusion, the mode shape showed the reversed quadratic curve. The natural frequencies of inclusion plate were decreased as the location of inclusion moves from the clamped edge to the tree edge.

• Journal of the Korean institute of surface engineering
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• v.35 no.3
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• pp.158-164
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• 2002

Nanocomposites consisting of a nanocrystalline brass matrix (grain size ; 20-100nm) with sub-micron sized Al2O3 particles (60-200nm) were prepared by pulsed current electrodeposition. The microhardness of the nanocomposite with a grain size of 90-100nm was approximately 1.7 times higher than that of a comparable electrodeposit with no particles. However, significant variations in microhardness were not observed between the nanocomposites with grain sizes of 20 nm and the comparable electrodeposit.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.555-556
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• 2001

가시망둑, Psudoblennius cottoides는 쏨뱅이 目(Scorpaeniformes), 독중개科(Cottidae)에 속하는 연안성 어류이며, 우리나라 남부와 제주도 연해 및 일본 각지 연해안에 분포한다(정, 1977; 김 등, 2001). 가시망둑에 대한 연구는 우리나라에서는 없고, 일본에서는 가시망둑의 산란(Shiogaki and Dotsu, 1974)과 난 및 자치어의 발달(Kimura et al., 1987)이 있으나 이들 연구 모두 자연에서 채집된 가시망둑의 어미를 사육수조내에서 순치하여 인위적으로 수정난을 획득하였기 때문에 자연상태에서의 정확한 산란습성을 밝히지 못하였다. (중략)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.318-324
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• 2007

We report on a strong violet luminescence emitted from the ZnO:Al films grown on glass substrate by radio-frequency magnetron sputtering. The growth of high-quality thin films and their optical properties are controlled by adjusting the mixture ratio of Ar and $O_2$, which is used as the sputtering gas. The crystallinity of the films is improved as the oxygen flow ratio is decreased, as evidenced in both x-ray diffractometer and atomic force microscope measurements. As for the violet luminescence measured by photoluminescence (PL) spectroscopy, the peak energy and intensity of the PL signal are decreased with increasing the oxygen flow ratio. The peak energy of the violet PL spectrum for the thin film with an oxygen flow ratio of 50 % is almost constant, regardless of the increase of laser Power and temperature. These results indicate that the violet PL signal is probably due to defects related to interstitial Zn atoms.

• Resources Recycling
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• v.16 no.6
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• pp.39-45
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• 2007

Optimum condition for neutralization has been studied to remove the copper and zinc ions from spent sulfate solutions which resulted from the acid washing of the base of brass bulb. Chemical distribution of copper and zinc species and the variation of solubility of the two ions with solution pH were obtained by considering the complex formation reaction and mass balance. Removal percentage of zinc was more sensitive to solution pH than that of copper. This results from the fact that the solubility of zinc is higher than that of copper. The form of coagulant affected little the removal percentage of zinc, while addition of coagulant as the phase of solution resulted in higher removal percentage of copper than as the phase of solid.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.1
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• pp.62-68
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• 1999

The strength data on AlBC3 and HBsC1 which are used for materials of marine propeller blade are insufficient as used of material limited and even rules of KR(Korean Register of Shipping) describe only a point of view that the chemical composition and men values of mechanical proper-ties have to be certain level. In this study distribution characteristics as well as mean values of mechanical properties are investigated through the tensile test and the characteristics of fatigue strength are investigated through the fatigue test.

• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.224-243
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• 2014

This study examined the materials and casting technology(cast, alloy, etc.) used in the manufacturing of bronze artifacts based on old literature such as Yongjae Chonghwa, Cheongong Geamul, and The Korea Review. In the casting experiment for restoration of Sangpyong Tongbo, a bronze and brass mother coin mold was made using the sand mold casting method described in The Korea Review. The cast was comprised of the original mold plate frame, wooden frame, and molding sand. Depending on the material of the outer frame, which contains the molding sand, the original mold plate frame can be either a wooden frame or steel frame. For the molding sand, light yellow-colored sand of the Jeonbuk Iri region was used. Next, the composition of the mother alloy used in the restoration of Sangpyong Tongbo was studied. In consideration of the evaporation of tin and lead during actual restoration, the composition of Cu 60%, Zn 30%, and Pb 10% for brass as stated in The Korea Review was modified to Cu 60%, Zn 35%, and Pb 15%. For bronze, based on the composition of Cu 80%, Sn 6%, and Pb 14% used for Haedong Tongbo, the composition was set as Cu 80%, Sn 11%, and Pb 19%. The mother coin mold was restored by first creating a wooden father coin, making a cast from the wooden frame and basic steel frame, alloying, casting, and making a mother coin. Component analysis was conducted on the mother alloy of the restored Sangpyong Tongbo, and its primary and secondary casts. The bronze mother alloy saw a 5% increase in copper and 4% reduction in lead. The brass parent alloy had a 5% increase in copper, but a 4% and 12% decrease in lead and tin respectively. Analysis of the primary and secondary mother coin molds using an energy dispersive spectrometer showed that the bronze mother coin mold had a reduced amount of lead, while the brass mother coin mold had less tin. This can be explained by the evaporation of lead and tin in the melting of the primary mother coin mold. In addition, the ${\alpha}$-phase and lead particles were found in the mother alloy of bronze and brass, as well as the microstructure of the primary and secondary coin molds. Impurities such as Al and Si were observed only in the brass mother coin mold.

• Journal of Powder Materials
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• v.28 no.5
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• pp.396-402
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• 2021

Stainless steel, a type of steel used for high-temperature parts, may cause damage when exposed to high temperatures, requiring additional coatings. In particular, the Cr₂O₃ product layer is unstable at 1000℃ and higher temperatures; therefore, it is necessary to improve the oxidation resistance. In this study, an aluminide (Fe₂Al₅ and FeAl₃) coating layer was formed on the surface of STS 630 specimens through Al diffusion coatings from 500℃ to 700℃ for up to 25 h. Because the coating layers of Fe₂Al₅ and FeAl₃ could not withstand temperatures above 1200℃, an Al₂O₃ coating layer is deposited on the surface through static oxidation treatment at 500℃ for 10 h. To confirm the ablation resistance of the resulting coating layer, dynamic flame exposure tests were conducted at 1350℃ for 5-15 min. Excellent oxidation resistance is observed in the coated base material beneath the aluminide layer. The conditions of the flame tests and coating are discussed in terms of microstructural variations.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.267-272
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• 2007

Al-doped ZnO (AZO) thin films were grown on glass substrates by radio-frequency magnetron sputtering. The effects of oxygen flow ratio, which was used for a sputtering gas, on the AZO thin films were investigated by using the X-ray diffraction (XRD), atomic force microscopy (AFM), and Hall effects measurement. The AZO thin film, deposited with oxygen flow ratio of 0% at the growth temperature of $400^{\circ}C$, showed a strongly c-axis preferred orientation and the lowest resistivity of $6.9{\times}10^{-4}{\Omega}cm$. The ZnO (002) diffraction peak indicated a tendency to decrease substantially with increasing the oxygen flow ratio. Furthermore, as the oxygen flow ratio was decreased, the carrier concentration and the hall mobility were increased, but the electrical resistivity was decreased.