• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.87-92
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• 2009

The effect of aging on the precipitation of the $\sigma$ phase and the corrosion resistance in tungsten substituted super duplex stainless steels was investigated. The volume fraction of the $\sigma$ phase and the current density increased with aging at temperatures up to $750^{\circ}C$ and then decreased. With an increase in aging time, the volume fraction of the $\sigma$ phase and the current density also increased. The $\sigma$ phase hardly influenced the corrosion resistance. With the substitution of tungsten for molybdenum in super duplex stainless steel, the volume fraction of the $\sigma$ phase and the current density decreased remarkably.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.325-328
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• 2008

Recently increasing interest in high-rise building around the world for more than 100 floor, the trend is the increasing use of high-strength and high-flowable concrete so as of productivity improvements and cost savings to improve the performance of the early strength development. This study is to reach the optimal combination by reviewing the performance of high-rise building which is required. The results, lower the ratio of W/B was an increase in compressive strength and early strength in the use of admixture decreased in the combination of higher replacement ratio of admixture.

• Journal of the Korea Institute of Building Construction
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• v.5 no.2 s.16
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• pp.153-159
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• 2005

This study is to choose the optimal mixture and to analyze the sensibility properties of High strength concrete and mass concrete to apply the high rising building. The main experimental variables were water/binder ratio $39\%,\;33\%,\;35\%\;and\;37\%$, replacement ratio of fly ash $5\%,\;10\%\;and\;15\%$, in the high strength concrete and water/binder ratio $39\%,\;41\%\;and\;43\%$, replacement ratio of fly ash $10\%,\;20\%\;and\;30\%$, in the man concrete. According to the test results, the principal conclusions are summarized as follows. 1) The slump(or slump flow) and air content of fresh concrete were found to be the highest in the elapsed time 30 minutes. 2) The optimal mixture conditions are W/B $40\%$, FA $25\%$ in the mass concrete and W/B $33.4\%$, FA $15\%$ in the high strength concrete. 3) The ranges of sensibility are satisfied in the moisture content ${\pm}l\%\;and\;S/a\;{\pm}2\%$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3~4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzaolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3∼4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.79-82
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• 2010

다중서열정렬 알고리즘은 생명정보학 분야에서 서열기반의 계통분류 분석에 가장 많이 사용되며, 가장 대표적인 공개 프로그램은 ClustalW로 사용자가 로컬시스템에 설치하여 이용할 수 있다. 그러나 실제로 사용자들이 ClustalW을 설치한 후, 서열데이터의 준비, 가공, 처리 및 타 시스템과 연동 등과 같은 작업을 하는데 여러 가지 어려움이 있다. 따라서 본 논문에서는 다중서열정렬 작업을 편리하고 빠르게 수행할 수 있는 웹기반의 고성능 다중서열정렬시스템을 제안한다. 제안된 시스템의 특징은, (1) Inter-Query 라우팅 알고리즘을 통해 다수의 PC 자원을 효율적으로 활용하여 계산 성능을 극대화하였으며, (2) 사용자 편의성을 고려한 웹인터페이스의 제공을 통해 개인화된 데이터관리, 실시간 모니터링, 데이터 편집 등을 지원하여 사용자가 손쉽게 서열데이터의 수집, 관리 및 처리할 수 있도록 지원한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.363-368
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• 2010

In this work, electrochemiluminescence (ECL) cell using nanocrysralline $TiO_2$ electrode and Ru(II) complex (Ru${(bpy)_3}^{2+}$) is fabricated for low-cost high-efficient energy conversion device application. The nanocrysrallme $TiO_2$ layer (${\sim}10{\mu}m$ thickness) with large surface area (${\sim}360m^2$/g) can largely inject electrons from nanoporous $TiO_2$ electrode and allows the oxidation/reduction of Ru(II) complex in the nanopores. The cell structure is composed of a glass/ F-doped $SnO_2$(FTO)/ porous $TiO_2$/ Ru(II) complex in acetonitrile/ FTO/ glass. The nanocrysralline $TiO_2$ layer is prepared using sol-gel combustion method. The ECL efficiency of the cell consisting of the porous $TiO_2$ layers was 250 cd/W, which was higher than that consisting of only FTO electrode (50cd/W). The nanoporous $TiO_2$ layers wwas effective for increasine ECL intensities.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.160-161
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• 2005

The $(Sr_{1-x}Ca_x)TiO_3$(SCT) thin films are deposited on Pt-coated electrode (Pt/TiN/$SiO_2$/Si) using RF sputtering method with substitutional contents of Ca. The optimum conditions of RF power and $Ar/O_2$ ratio were 140[W] and 80/20, respectively. Deposition rate of SCT thin film was about 18.75$[{\AA}/min]$. The dielectric constant was increased with increasing the substitutional contents of Ca, while it was decreased if the substitutional contents of Ca exceeded over 15[mol%]. All SCT thin films used in this study show the phenomena of dielectric relaxation with the increase of frequency, and the relaxation frequency is observed above 200[kHz].

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.641-650
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• 2010

The concrete cracking from the restrained stress caused by the shrinkage may play significant cause of deterioration of concrete structures by allowing the permeation of sulphate and chloride ions which in turn triggers corrosion of steel reinforcement. In particular, the cracking becomes more critical as water binder ratio (W/B) is reduced and concrete strength increases. Therefore, it needs to evaluate correctly the comprehensive shrinkage behavior of concrete with high strength: high-strength concrete (HSC), ultra-highstrength concrete (UHSC). The unrestrained shrinkage tests, however, cannot estimate the net shrinkage effectively which affects cracking after full development of strength and stiffness because it does not consider the degree of restraint, strength development, stress relaxation, and so on. Therefore, in this study, both free and restrained shrinkage tests with variables of W/B (W/B of 30, 25 and 16%) and admixtures (fly ash (FA) and granulated blast-furnace slag (BFS)) for HSC, very-high-strength concrete (VHSC) and UHSC were performed. The test results indicated that the autogenous shrinkage and total shrinkage at drying condition were reduced as W/B increased and FA, BFS were added, and the cracking behavior was suppressed as W/B increased and FA was added.

• 전기의세계
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• v.28 no.2
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• pp.23-28
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• 1979

압전 세라믹 소자는 강유전성 세라믹에 높은 직류전압을 가한 후에 나타나는 압전효과를 이용하는 것으로 전압을 제거한 후에도 압전효과가 존재하는 것이 강유 전체의 특징이다. 압전효과를 나타내는 것은 천연으로 존재하는 수정이 있고, 인조품으로서는 BaTiO$_{3}$가 2차 대전후 W.P Mason에 의해 연구되어 압전재료로서 사용되었지만 BaTiO$_{3}$는 공진주파수의 온도안정성이 문제가 된다. 그후 B.Jaffe et al.은 P$_{b}$(Z$_{r}$, T$_{i}$)O$_{3}$등 몇가지 복합 Perovskite 산화물 중에서 P$_{b}$(Z$_{r}$, T$_{i}$)O$_{3}$의 $P^{2+}$$_{b}$ 이온을 다른 이온으로 치환하면 큐리 온도가 변하고 실온에서의 유전율도 크게 변화한다는 것이 밝혀졌다. 여기서 논하고저 하는 것은 압전소자의 제법과 성질 또 이의 특성을 좁은 범위 내에서 소개코저 한다.