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평면굽힘하중을 받는 표면미소균열의 프랙탈 특성에 관한 연구
장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1
Irregular shapes and growth behavior of surface nicro-crack showed very complex and nonlinear properties and many investigators have performed theoretical analyses and experiments on them to characterize fatigue strength. They had difficulties in estimating fatigue life due to random distribution, growth and coalescence of surface micro-cracks. The straightness of crack growth along intergranular and transgranular was prevented from irregular microstructure and precipitates. Euclid geometry can't quantify shape of surface micro-crack but fractal geometry can. Therefore, it is suggested that average fractal dimension of surface micro-cracks is able to estimate fatigue life but fractal dimension of maximum surface micro0crack is not in Al 2.24-T3 alloy.
[논문]실시간 정밀 3차원 지형측량기법을 이용한 저수량산출시스템 개발
송석진,장용구,김상석,강인준 釜山大學校生産技術硏究所 2004 生産技術硏究所論文集 Vol.63 No.-
현재 고정밀도 저수량 측량에 사용되는 측량장비에는 수평위치결정방법으로 실시간 DGPS측량장비가 많이 활용되고 있고, 수심측량에는 디지털 음향측심기를 많이 사용하고 있다. 본 연구에서는 현재, 수심측량 결과처리 시 문제가 되고 있는 소프트웨어의 가격부담을 줄이고 수심측량과 내업처리에 의한 저수량산출을 통합처리 할 수 있는 국내 자체개발의 저가형 외 · 내업 일체형 저수량산출시스댐을 개발하였다.
X선 회절을 이용한 Al 2024-T3합금의 피로강도추정에 관한 연구
장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1
The fatigue process can be roughly divided into four stages ; cyclic hardening/softening, crack nucleation, crack propagation, and fracture. X-ray diffraction techniques can measure residual stress on the basis of the change of lattice plane spacings and half-value breadth corresponding to nonuiform strain in the constituent grains. The half-value breadth decreased with increase of number of cycles and stress range. The change of half-value breadth in crack nucleation is dependent on applied stress range. The relationship between propagation life ratio(N-Nc)/Nf and crack propagation half-value breadth ratio (Hw-Hwc)/Hwo shows strong linear behavior. Therefore, the remaining life of mechanical components can be predicted using half-value breadth ratio on crack nucleation and in process of crack propagation.
X선 반가폭을 이용한 자동차 압연강의 피로수명평가에 관한 연구
장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1
In order to predict the fatigue life using X-ray diffraction techniques, in-plane bending fatigue test was carried out for SPCC steel. The relation between fatigue damage on the specimen surface and half-value breadth of X-ray diffraction lines was investigated in the process of cyclic loading. The change of half-value breadth B consisted of the three sequent except stress amplitude near fatigue limit. On the first stage, half-value breadth B decreased rapidly, on the second stage slightly, and on the third stage rapidly. B/B0-logNf relationship showed linear behavior except the early part of life. The slople of the seemed to take constant value regardless stress amplitude. On the other hand, Nf line was able to be expressed by a straight line on the B/B0-logNf relationship. Therefore, it was possible to prepose a method estimating the fatigue life fraction N/Nf using the gradient of B/B0-logNf relationship and the N? line.
SS41불림재와 M.E.F.복합조직강의 X-선 잔류응력거동에 관한 연구
장득열,조석수,김득진 三陟大學校 1998 論文集 Vol.31 No.1
This study verified the relationship between fracture mechanics parameters ΔK, Kmax and X-ray residual stress σr for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). X-ray stress constant K was determined for the diffraction line of (211) plane using Cr-Kα radiation. K was -340.87 MPa/deg. The fatigue crack propagation test were carried out under stress ratios of 0.1 and 0.5 and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface Residual stress σr were independent on stress ratio (R=0.1, 0.5) by arrangement of ΔK. The equation of σr-ΔK was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.
장향동,백광균,구경림,옥선미,최진석,고은주,류성렬 한국공업화학회 2004 응용화학 Vol.8 No.2
Aflatoxin B₁ was known to have the strongest poisonous character among Aflatoxin compounds. To search the production of Aflatoxin B1 according to the change of temperature, relative humidity and incubation days, orange incubated with Aspergillus parasiticus KCCM 35078 was incubated at 20℃, 25℃, 30℃ at relative humidity 60%, 70%, 80% and for incubation time 3, 4, 5, 6, 7 days.. Production of Aflatoxin B₁ shows that the highest production appeared at 25℃ and its relative humidity 70%. The result that was quantitatively analyzed by using HPLC was 77.41ppm, and by using Fluoroscence detector was 87.87ppm. - Production of Aflatoxin B₁ shows that the lowest production appreared at 20℃ and its relative humidity 80%(HPLC), 60%(Fluoroscence detector). The result that was quantitatively analyzed by using HPLC was 4.47ppm, and by using Fluoroscence detector was 4.17ppm. The structure of Aflatoxin B₁ was identify with authentic sample by using instrumental analysis methods of GC/MS, ¹H-NMR, FT-IR respectively.
전진욱,최장석 인제대학교 1999 仁濟醫學 Vol.20 No.1S
전산화단층촬영과 자기공명영상은 척추관협착증의 진단과 척추체유합술 및 척추경을 통한 나사못 삽입술 등 척추질환의 진단과 치료에 중요한 정보를 제공하고 있다. 저자들은 요천추의 전산화단층촬영과 자기공명영상 100예씩 총 200예를 대상으로 한국 성인의 제1 요추에서부터 제1 천추까지의 척추체, 척추과, 척추경을 조사하여 척추관협착증의 진단, 척추체유합술에 이식골의 크기와 척추경을 통한 나사못의 길이, 나사못의 굵기와 삽입각도 결정에 기본 자료로 활용하려 하였다. Magnetic resonance image(MRI) and computed tomography(CT) provided information for diagnosis of spinal stenosis, and for interbody fusion and instrumentation of transpedicular screw. The author had reviewed the 200 cases of MRI and CT scanning of spine for the measurement of vertebral body canal and pedicle from first lumbar vertebra to first sacral canal. The results were as follows. 1.Anteroposterior, transverse diameter and height of vertebral body increased steadily from first lumbar vertebrar to first sacral vertebra. 2.The narrowest transverse diameter of pedicle was seen at first lumbar vertebra (9.0mm) and the widest at the first sacral(20.4mm). 3.The widest superoinferior diameter of pedicle was seen at first lumbar vertebra (13.1mm) and the narrowest at third lumbar(11.8mm). Above data could be used in diagnosis of spinal stenosis, in decision of the size of bone graft in interbody fusion and length, diameter and insertion of angle of transpedicular screw.
평균기울기법에 의한 Al 2024-T3합금의 X선 반가폭과 피로수명비의 관계
조석수,박승용,김득진,장득렬,주원식 東亞大學校 大學院 1998 大學院論文集 Vol.23 No.-
In order to predict the fatigue life fraction for Al 2024-T3, in-plane bending fatigue test and X-ray diffraction techniques was carried out. The relation between fatigue damage on the specimen surface and half-value breadth of X-ray diffracton lines was investigated in the process of cyclic loading. This paper proposed the estimation of fatigue life using AGM(Average Gradient Method) by the Gradient on the basis of B/Bo and log N/Nf.