• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.129-134
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• 2005

The $^{87}Sr/^{86}Sr$ ratios between water and biogenic material are similar in marine and lacustrine environment. Pb isotope ratios we, however, reported not to have been corresponding between the biological tissues and ambient water in aquatic system, contrary to the Sr isotope ratios. In order to explore the potential application of two isotopes as environmental tracers, we report here the isotopic compositions of strontium and lead of gastropod shell in fresh water in Jinan area. The $^{87}Sr/^{86}Sr$ ratios of carbonate shells of gastropod living in fresh stream water, are similar as that of ambient water but are different by sites. The different $^{87}Sr/^{86}Sr$ ratios of stream water between the sites is likely caused by the difference of the isotopic composition of Sr derived form rocks in the basin. In contrast, there is a distinct difference of the lead isotopic values between the water and the gastropod shell, suggesting that shell-fish available lead in aquatic system is different from dissolved lead in water. It is assumed that the majority of Pb in stream water is derived from atmospheric Pb accumulated on soil materials over years rather than from rock.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.664-666
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• 2002

본 논문에서는 비디오 서버의 startup latency를 줄이기 위한 replication 기술 및VCR 기능을 지원하기 위한 기술의 개요에 대해서 설명하고 VCR 기능을 지원하기 위해XPRS 파일에서 SR을 응용한 알고리즘을 제안하였다. 이 알고리즘은 XPRS 파일에서 액세스 빈도에 따라 블록의 수를 다르게 하는 알고리즘으로 VOD 서비스의 효용성을 높여줄 수 있는 VCR 기능을 효율적으로 지원할 수 있다. 또한 SR과 SR 응용 알고리즘을 이용하여 시스템의 성능을 최적화할 수 있는 재구성 알고리즘을 제안하였다. 본 논문에서 제안한 알고리즘은 블록 skipping 기술을 지원하지 않기 때문에 향후 이 기술과 연계한 연구가 지속적으로 요구된다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.120-122
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• 2010

In this paper the effect of constituent content on superconductivity and phase in BiPbSrCaCuO system was reported. The zero resistance temperature reaches as high as 100k when dophant Sb was decreased dramatically with increasing Sb content in BiPbSrCaCuO system while the corresponding phase was changed fundamentally.

• Journal of Adhesion and Interface
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• v.9 no.3
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• pp.14-19
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• 2008

In this study, silicone rubber (SR40) and fluororubber (FKM) mixture blends were prepared by various weight percentages, and their properties were characterized. The crosslinking rate increased as the contents of SR40 due to the crosslinking agent in SR40. As contents of FKM increase in SR40/FKM blends, thermal decomposition temperature of blends increased. When SR40/FKM blend ratio was at 50/50, the thermal decomposition stabilization was higher than that of pure SR40. The contact angle of SR40/FKM blend increased as the increase of SR40 contents in blend. All composition of SR40/FKM blends showed typical phase separation morphology. As the contents of SR40 increase in SR40/FKM blend, the degree of separation in SR40/FKM blends also increased.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.33-35
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• 2014

We report here results of a study of superconductivity in the ($Ta_{1-x} Sn_x)Sr_2EuCu_2O_z$ system. We observe resistive superconducting transitions for the samples with x = 0.15-0.3, and the highest superconducting transition has been achieved for the sample with x = 0.2 which reveals onset $T_c$ of 43 K and zero-resistivity of 25 K. Thermoelectric power measurements indicate that Sn doping introduces holes into the system and thereby superconductivity can be achieved in the ($Ta_{1-x} Sn_x)Sr_2EuCu_2O_z$ system.

• Computational Structural Engineering
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• v.3 no.1
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• pp.71-81
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• 1990

The isolation system is installed at the base of a structure for reduction of the earthquake damage to the structure. In the 1970', when the laminated rubber bearing(LR type) is developed, the isolation system is put in practice. And recently a new isolation system(SR type), including the laminated rubber bearing with the friction plate beneath, is developed. In this thesis, a study on the base isolation effect, for various of the isolation system and structure properties, is performed. The results of this parameter study show that the isolation system can reduce the earthquake damage of the building structures significantly. As the period of isolation system increases, the isolation effect increases and converges to zero damage. As the number of story increases, the isolation effect reduces. It is found that SR type isolation system is more effective than LR type because SR type base isolation system reduces acceleration, drift and total displacement.

• Journal of the Korean Ceramic Society
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• v.28 no.4
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• pp.261-268
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• 1991

The dielectric properties and microstructure of SrTiO3-based grain boundary layer (GBL) capacitor were investigated, and SrTiO3 GBL capacitor was made by penetrating the Frit (PbO-Bi2O3-B2O3 system). The Nb2O5-doped SrTiO3 ceramics were fired for 4-hours, at 145$0^{\circ}C$ in H2-N2 atomsphere to get semiconductive ceramics. The grain size of SrTiO3 sintered at reduction atmosphere had increased as the amount of Nb2O5 increases and then decreased as the amount of Nb2O5 exceeded 0.2 mole%. Insulating reagents which contained PbO-Bi2O3-B2O3 system frit and oxide mixture were printed on the each semiconductive ceramics and fired at varying temperature and for different holding time. The optimum dielectric properties could be obtained by second heat treatment at 110$0^{\circ}C$ for 1 hour, when frit paste was printed. A SrTiO3-based GBLC had the apparent permitivity of about 3.2$\times$104, the dielectric loss of 0.01~0.02 and the stable temperature coefficient of capacitance. The influence of frit paste on dielectric properties was similiar to that of oxide paste but the stability of temperature property of capacitance was improved.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.138-138
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• 2001

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.48-59
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• 2009

Next generation mobile communication system will have various access networks and provide seamless multimedia data service to mobile nodes. The WiNGS system, one of these access network, has superior RAT(Radio Access Technology) and network connectivity other than previous ones. In this paper, we propose link-layer SR-ARQ between mobile node and WAGW to solve packet re-ordering problem during handover. In the proposed scheme, we apply the adaptive timer at the SR-ARQ sender to reduce unnecessary packet retransmission during handoff and delayed NAK algorithm at the SR-ARQ receiver for delaying NAK response due to temporary out-of-sequenced frames. We evaluate the performance of the proposed scheme by implementing the new SR-ARQ protocol at the link-layer using ns-2 simulator, and show the handover performance is improved greatly by preventing unnecessary retransmission.

• Applied Microscopy
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• v.47 no.3
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• pp.187-202
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• 2017

The classical electron band theory is a powerful tool to describe the electronic structures of solids. However, the band theory and corresponding density functional theory become inappropriate if a system comprises localized electrons in a scenario wherein strong electron correlations cannot be neglected. $SrRuO_3$ is one such system, and the partially localized d-band electrons exhibit some interesting behaviors such as enhanced effective mass, spectral incoherency, and oppression of ferromagnetism and itinerancy. In particular, a Metal-Insulator transition occurs when the thickness of $SrRuO_3$ approaches approximately four unit cells. In the computational studies, irrespective of the inclusion of on-site Hubbard repulsion and Hund's coupling parameters, correctly depicting the correlation effects is difficult. Because the oxygen atoms and the symmetry of octahedra are known to play important roles in the system, scrutinizing both the electronic band structure and the lattice system of $SrRuO_3$ is required to find the origin of the correlated behaviors. Transmission electron microscopy is a promising solution to this problem because of its integrated functionalities, which include atomic-resolution imaging and electron energy loss spectroscopy.