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.

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.

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.

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.

자연환경방사선에 의한 피폭선량(유효선량당량)의 종합적 해석연구

전재식,채하석,이병영,김현창,이동준,김도성,엄두하 충남대학교 기초과학연구소 1990 연구논문집 Vol.10 No.-

자연환경방사선의 세 가지 주요 요소인 지각방사선, 우주선 전리성분 및 라돈과 그 자핵종이 주는 선량을 측정, 해석하였는 바 18개월간에 걸쳐 대전, 수원, 경산 지역에 대하여 수행하고 이를 종합하여 유효선량당량으로 평가하였다. 지각방사선과 우주선 전리성분 측정을 위하여 3"∮×3" Nal(Tl) 섬광검출기와 휴대형 다중파고분석기를 이용한 감마선 분광분석 및 ^7LiF PTEE disk TLD에 의한 적산선량측정을 병행하였고, 공기중 라돈농도의 측정은 CR-39 고체비적검출기를 내장한 라돈컵을 설계제작하여 사용하였으며 비적수 라돈농도 교정인자는 스웨덴 국립방사선 방호연구소의 표준 라돈 챔버내에서 조사하여 결정하였다. 세 지역의 가연방사선에 의한 유효선량당량에는 약간의 수치적 차이는 있었으나 본질적 차이는 찾아볼 수 없었으며 지역 측정치의 분산가중 평균치는 지각방사선 (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍh^-1], 우주선 전리성분 (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1]로 외부 피폭이 (775±9)uSvㆍy^-1[(88.5±1.0)nSvㆍy^-1]였으며 라돈과 그 자핵종에 의한 내부피폭은 (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1]였다. 따라서 자연황경방사선에 의한 여간 총 선량당량은 (2762±296)uSvㆍy^-1[(315.3±34.0)nSvㆍh^-1]로 평가되었는데 이 값들은 UN보고서^(11)에 나온 “정상적 자연방사선 지역”의 값과 비교할 만한 타당한 값으로 나타났다. Assessment of effective dose equivalent from natural environmental radiation that consists of terrestrial gamma­ray, ionizing component of cosmic­ray and alpha­rays of atmospheric radon and its decay products has been carried out for 18 months in Daejeon, Suwon and Kyungsan areas. A 3"∮×3"cylindrical Nal(Ti) scintillation detector in association with portable multichannel analyser and ^7LiF PTFE disk TLDs were used for the measurement of terrestrial gamma­ray and cosmic­ray ionizing component, while self­designed radon­cups with CR-39 SSNTD attached to the inside bottom were used for the integral measurement of at­mospheric radon concentration. Determination of calibration factor for converting track density of CR-39 detector to radon concentration was made by irradiation of radon­cups in the standard radon chamber of Swedish National Institute of Radiation Protection. Although resultant effective dose equivalents of three different measurment points show minor numerical differences, no essential discripancy between the places was found. The variance weighted means of the annual effective dose equivalents of each component of radiation from the tree places came out to be: (463±3)uSvㆍy^-1[(52.9±0.3)nSvㆍy^-1] for terrestrial gamma­ray, (287±15)uSvㆍy^-1[(32.8±1.7)nSvㆍy^-1] for ionizing component of cosmic­ray and (1973±298)uSvㆍy^-1[(225.2±34.0)nSvㆍy^-1] for internal exposure of radon and its decay products. Consequent total effective dose equivalent turned out to be (2762±298)uSvㆍy^-1[(315.3±34.0)nSvㆍy^-1], which if reasonably comparable with that appeared in UNSCEAR Report^[11]as per caput annual effective dose equivalent in “areas of normal back ground radiation.”

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

CdS:In 單結晶의 基本特性과 photosensor로의 應用

강현식,박병채,장성우,이해익,최용대 全北大學校 敎育大學院 1986 敎育論叢 Vol.6 No.-

The opto-electrical properties of the CdS : In single crystals were studied by these means of the scanning electron microscope, X-ray diffraction, optical transmission & photoconductivity, resitivity variation v.s. impurites, and resitivity v.s. photon flux change. By X-ray diffraction measurement, the structure was found to be hexagonal and the lattice constant was calculated to be a_o=4.13Å and c_o=6.75Å The band gap was estimated to be about 2,419eV (300K). By the transmission measure ments a donor impurity level of In or Al was 0.024eV below the conduction level edge. For the application on the photosensor, the resistivity(ρ) variation of the CdS : In was measured with respect to photon flux(P_o) change and to wavelength, the resistivity was found to be ρ=8.75×10^6P_o^-125 (Ω―㎝/Lux) and the photoconductivity showed its highest response peak between 5,000Å and 5,400Å ranges.

음향방출 신호처리에 의한 플라즈마용사코팅 피막부식재의 파손해석

김귀식,박경석,홍용의,현창해 제주대학교 산업기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.1

This paper was to investigate of a adhesiveness of the plasma sprayed coating materials did a salt spray by acoustic emission method in tensile loading. The powders used for the coating were nickel aluminum composite powder Ni-4.5wt.%Al and titanium dioxide powder TiO2. These powders were coated on a carbon steel S45C by plasma spray method. The salt solution was a 5% NaCl and the salt spray times were 2, 5 and 10 hours respectively. The salt solution penetrated into the surface of the substrate through pore of the coating layer built in the process of plasma spay. 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 increased. The AE amplitudes increased at strain range of 6%-11%.

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.