아연피복강재의 부식피로 균열성장특성

현창해,오맹종,현경수,김귀식 濟州大學校工科大學産業技術硏究所 1996 尖端技術硏究所論文集 Vol.7 No.1

Corrosion fatigue crack growth behaviors of Zinc coating steel, SGH41, in 3% NaCl aqueous solution was investigated with a hydraulic fatigue testing machine. A hydraulic fatigue test machine was manufactured using a personal computer, a proportional valve one, a hydraulic system. Corrosion fatigue crack growth rates of SGH41 is reduced than that of the uncoated steel by anti-corrosion effect of zinc. Paris rule, da/dN=C(ΔK)? is applied about the relation between the stress intensity factor range, ΔK, and crack growth rate, da/dN, of both the coated specimen and the uncoated one. Where the slope of the correlation, m, is 2.24 for the coated specimen and 3.66 for the uncoated one. The corrosion sensitivity, (da/dN)corr/(da/dN)air, of the coated specimen was smaller than that of the uncoated specimen.

유압피로시험기의 제작

현경수,현창해,김귀식,오맹종 濟州大學校工科大學産業技術硏究所 1995 尖端技術硏究所論文集 Vol.6 No.-

A hydraulic fatigue test machine was manufactured using a personal computer and a proportional valve, a hydraulic system. This machine was controlled loading waves and stress ratios, frequency by personal computer. A numerical simulation for the dynamic quality of this machine was done by 4 order Runge-Kutta method. Corrosion fatigue crack growth behaviors of SPH41 in 3% NaCl aqueous solution were investigated with this machine. Corrosion fatigue crack growths of this steel were reduced than the uncoated steel by anti-corrosion effect of zinc.

AE에 의한 용사코팅 부식재의 박리해석

김귀식,손창환,홍용의,현창해 제주대학교 공과대학 첨단기술연구소 2003 尖端技術硏究所論文集 Vol.14 No.2

This paper is to investigate the adhesiveness between substrate and coating layer and the effect of corrosion by acoustic emission method in tensile loading. The used powders are Zn and Al. There are coated on brass alloy substrate, respectively. AE signals of Zn and A1 coating layer increase drastically in strain 2%. but that of Zn specimen have more than that of Al specimen. When the specimens axecuted under 3.5% NaCl solution for 500 hours, the salt solution penetrated into the surface of the substrate through pore of the coating layer. Corrosion production formed on the surface of substrate. The adhesiveness between coating layers is weaken by the polarization and corrosion itself. The AE events, count and energy of corroded coating specimens decreased in comparison with specimens without corrosion. Especially Zn specimen deoreased more than Al specimen in strain 2%.

Al과 Zn 용사코팅재의 캐비테이션 침식에 관한 연구

김귀식,현창해,진희석 제주대학교 공과대학 첨단기술연구소 2003 尖端技術硏究所論文集 Vol.14 No.2

The hydraulic machinery of screw propeller and pump impellers is damaged by cavitation erosion in sea water. The cavitation erosion is a phenomenon lead to a functional disorder of various fluid machinery and drop off in efficiency by cavity fluid fluctuation. In this study is investigated the cavitation erosion of Zn and Al coatings made by thermal spraying methods. These metals are coated on substrate of high strength brass. Test specimens are immersed in 3.5% NaCl solution along 500 and 1000 hours, respectively. After pre-corrosion, the cavitation erosion test conducted on the coating specimens in 3.5% NaCl solution along 210 minutes. The cavitation erosion rates of the coating specimens were increased with pre-corrosion times. The weight loss Al coating was smaller than that of Zn. The weight loss rates of Zn and Al coating heavily increased at the initial stage of cavitation test, regardless of the test conditions.

유압피로시험기의 제작

김규식,현창해,현경수,오맹종 濟州大學校 産業技術硏究所 1995 산업기술연구소논문집 Vol.6 No.-

A hydraulic fatigue test machine was manufactured using a personal computer and a proportional valve, a hydraulic system. This machine was controlled loading waves and stress ratios, frequency by personal computer. A numerical simulation for the dynamic quality of this machine was done by 4 order Runge-Kutta method. Corrosion fatigue crack growth behaviors of SPH41 in 3% NaCl aqueous solution were investiged with this machine. Corrosion fatigue crack growths of this steel were reduced than the uncoated steel by anti-corrosion effect of zinc.

소형 스크류 프로펠라의 부식제거장치 개발

김귀식,현창해,한세웅 제주대학교 공과대학 첨단기술연구소 2004 尖端技術硏究所論文集 Vol.15 No.1

The materials of ship screw propeller are commonly the manganese bronze. The seawater corrosion and cavitation of the screw propeller reduce the propulsive performance of ship. In screw manufactory, the corrosion rust of the screw propeller is removed by a hand grinding. The grinding work makes the dust of the heavy metals from the manganese bronze. The dust makes indoor working environment poor. A friendly-environmental and automatic corrosion removing apparatus was developed for the improvement of screw processing and working environment. The corrosion rust of a screw propeller was remarkably removed by using apparatus. And the screw surface roughness was improved by a blasting effect of the apparatus performance test. Anode polarization curves on four processing conditions, that is to say, grinding, blasting, wire-brushing, fine sand papering, were confirmed by a potentiostat. Especially, two kinds of medials, alumina and emery, were used in the blasting processing. This result proved that the blasting work has considerably improved the corrosion resistance of a screw propeller.

아연피복강재의 부식피로 균열성장특성

김귀식,현창해,현경수,오맹종 濟州大學校 産業技術硏究所 1996 산업기술연구소논문집 Vol.7 No.1

Corrosion fatigue crack growth behaviors of Zinc coating steel, SGH41, in 3% NaCl aqueous solution was investiged with a hydraulic fatigue testing machine. A hydraulic fatigue test machine was manufactured using a personal computer, a proportional valve one, a hydraulic system. Corrosion fatigue crack growth rates of SGH41 is reduced than that of the uncoated steel by anti-corrosion effect of zinc. Pans rule, da/dN=C(ΔK)^(m) is applied about the relation between the stress intensity factor range, ΔK, and crack growth rate, da/dN, of both the coated specimen and the uncoated one. Where the slope of the correlation, m, is 2.24 for the coated specimen and 3.66 for the uncoated one. The corrosion sensitivity, (da/dN)_(corr)/(da/dN)_(air), of the coated specimen was smaller than that of the uncoated specimen.

AE에 의한 플라즈마 용사코팅 염수분무 부식재의 인장해석

김귀식,박경석,홍용의,현창해 제주대학교 공과대학 첨단기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.2

Thermal spray coating is formed by a process in which melted particles flying with high speed towards substrate, then crash and spread on the substrate surface cooled and solidified in a very short time. Stacking of the particles makes coating. This paper was to investigate the adhesiveness of the plasma sprayed coating materials conducted 5% NaCl salt spray by acoustic emission method in tensile loadings. The powders used for the coating were nickel aluminum composite powder Ni-4.5wt.%Al and titanium dioxide powder TiO_2. The salt solution penetrated into the surface of the substrate through pore of the coating layer built in the process of plasma spray. Corrosion productions formed on the surface of substrate. The adhesiveness between the substrate and the coating layer is weaken by corrosion and the exfoliation initiated chiefly at the corrosion surface of the substrate. The AE events and energy of the corroded coating specimens decreased as the salt spray times increase.

열산화된 알루미늄이 첨가된 Tin black filter를 가지는 메탄센서

권오식,황숙이,심창현,임채근,방영일,김봉철,허증수,류기홍,이덕동 경북대학교 센서기술연구소 2002 센서技術學術大會論文集 Vol.13 No.1

철근콘크리트 쌍곡냉각탑의 해석 및 설계

장현옥,민창식 동국대학교 산업기술연구원 1999 산업기술논문집 Vol.14 No.-

막력과 휨 모멘트를 받는 판형과 쉘 요소의 보강철근 설계를 위한 반복적 수치해석 알고리즘을 제시하였다. 평형방정식에 의하여 직교하는 방향으로 윗면과 아래 면에 배치되는 철근력의 설계식을 유도하였다. 국부적으로 재하된 외력과 내부에 발생하는 내력의 평형상태를 고려하여 계산되는 위치의 철근량을 결정하게 된다. 쌍곡 냉각탑에 대한 비선형해석을 수행한 결과 인장강성계수가 10에서 15까지 증가했을 때 계산된 극한하중이 설계극한하중의 약 51%에서 53%까지 초과하였다. 이는 설계방법이 본 연구에서 해석한 쉘의 극한하중에 대해서 소성이론의 하계정리가 적용될 수 있음을 보여주었고, 따라서 본 설계방법의 타당성을 입증하고 있다고 볼 수 있다. 이러한 결론을 일반화하기 위해서는 여러 형태의 철근콘크리트 쉘 구조물에 대해서 설계와 해석이 행해져야 할 것이다. An iterative numerical computational algorithm is presented to design a plate of shell element subjected to membrane and flexural forces. Based on equilibrium consideration, equations for capacities of top and bottom reinforcements in two orthogonal directions have been derived. The amount of reinforcement is determined locally. i.e., for each sampling point from the equilibrium between applied and internal forces. Based on nonlinear analyses performed in a hyperbolic cooling tower, the analytically calculated ultimate load exceeded the design ultimate load from 51% to 53% for an analysis with relatively low to high tension stiffening, case γ=10 and 15. For these cases, the design method gives a lower bound on the ultimate load with respect to lower bound theorem. This shows the adequacy of the current practice at least for this cooling tower shell case studied. To generalize the conclusion more designs - analyses should be performed with different shell configurations.