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초음파를 이용한 구조물 내부의 균열 및 미소 결함 검출
임병수(Byeongsoo Lim),배시연(Siyeon Bae),정찬서(Chanseo Jeong) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The initiation and growth of internal defects usually cause the failure of long term operated structural components at high temperature. Therefore, by investigating the internal defects of material, the integrity of the system can be maintained and the unexpected failure can be prevented. The main purpose of this study is to investigate the possibility of the application of ultrasound to the measurement and estimation of the creep damage. In this study, the phased array ultrasound and backward ultrasound were employed to detect the internal defects caused by creep. The former is suitable for the detection of defects existing deep in structure while the latter is for the defects on the surface or in shallow region. Using the newly developed P92 steel. both creep and NDE ultrasound tests were performed. The results of defect inspection were checked by microstructure examination. Reliable information on the size and position of crack were obtained and successful estimation of the amount of micro-voids and their distribution proved to be obtainable by the ultrasound inspection technique. The width of the creep degraded zone was confirmed by the width of ultrasonic signal, and the severity of degradation was confirmed by ultrasonic amplitude.
비선형 유한요소법을 이용한 Rubber Air Spring 복합소재의 보강코드 각도에 따른 응력과 변형률 특성 예측
정노진(Nojin Jeong),김청운(Chungwoon Kim),김병수(Byeongsoo Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
Air spring is the suspension, and it helps the improvement of stability and comfort by improving the impact-reliefㆍbrakingㆍcornering. The main composition of Air Spring is the upper plate, lower plate, and rubber sleeve. Rubber sleeve is the composite which is made up of combination of rubber and nylon, and the special quality is changed according to the shape of rubber-sleeve, the angle of reinforcement cord. This study performed to analyses the distribution of internal stresses and deformation for rubber composite material using non-linear finite element method. The study shows internal maximum stresses and deformation according to the changes of cord angle, resulting the smaller the Young's modulus becomes, the more maximum stresses decrease.
정찬서(Chanseo Jeong),김범준(Bumjoon Kim),임병수(Byeongsoo Lim) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
The effect of temperature on the material damage such as a crack is important especially for the materials and<br/> components operating at high temperature. Since a lot of mechanical components are welded, this effect as well as<br/> the effect of hardness and strength on the crack growth must be investigated separately for the welded and<br/> base(parent) materials. In this study, the above effects are investigated using P92 and P122 high temperature alloy<br/> steels. The tests for crack growth characteristics against the temperature under fatigue and creep load conditions were<br/> investigated. The fracture life according to the cavity generation that occurs during creep crack growth was<br/> investigated. Cavity investigations were carried out using SEM pictures and image analysis.
정찬석(Chanseo Jeong),임병수(Byeongsoo Lim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Fatigue crack growth has been characterized by Paris law and it was found that fatigue crack growth rate increased linearly with stress intensity factor range only up to a certain test temperature, and above it, Paris exponent value increased instead. To verify the temperature effect, a series of high temperature fatigue crack growth tests were carried out at 400,500,550,600,625,650 and 700℃. At 600~700℃, creep rupture tests were conducted as well to investigate the creep behavior with temperature. Based on such experimental characteristic results, the effect of temperature could be evaluated. Also, further analysis has been carried out to find the effect of temperature on the fracture mode shift, dimple formation and its role in crack growth rate and deformability at high temperature.<br/>
비선형 유한요소법을 이용한 상용차량용 Air Spring의 보강코드 각도에 따른 응력과 변형률 특성 및 평가
정노진(Nojin Jeong),김청운(Chungwoon Kim),김병수(Byeongsoo Kim) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Air spring is the suspension, and it helps the improvement of stability and comfort by improving the impact-reliefㆍbrakingㆍcornering. The main composition of Air Spring is the upper plate, lower plate , and rubber sleeve. Rubber sleeve is the composite which is made up of combination of rubber and nylon, and the special quality is changed according to the shape of rubber-sleeve, the angle of reinforcement cord . This study performed to analyses the distribution of internal stresses and deformation for rubber composite material using non-linear finite element method. The study shows internal maximum stresses and deformation according to the changes of cord angle, resulting the smaller the Young's modulus becomes, the more maximum stresses decrease.
TOFSIMS-P: a web-based platform for analysis of large-scale TOF-SIMS data.
Yun, So Jeong,Park, Ji-Won,Choi, Il Ju,Kang, Byeongsoo,Kim, Hark Kyun,Moon, Dae Won,Lee, Tae Geol,Hwang, Daehee American Chemical Society 2011 ANALYTICAL CHEMISTRY - Vol.83 No.24
<P>Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been a useful tool to profile secondary ions from the near surface region of specimens with its high molecular specificity and submicrometer spatial resolution. However, the TOF-SIMS analysis of even a moderately large size of samples has been hampered due to the lack of tools for automatically analyzing the huge amount of TOF-SIMS data. Here, we present a computational platform to automatically identify and align peaks, find discriminatory ions, build a classifier, and construct networks describing differential metabolic pathways. To demonstrate the utility of the platform, we analyzed 43 data sets generated from seven gastric cancer and eight normal tissues using TOF-SIMS. A total of 87?138 ions were detected from the 43 data sets by TOF-SIMS. We selected and then aligned 1286 ions. Among them, we found the 66 ions discriminating gastric cancer tissues from normal ones. Using these 66 ions, we then built a partial least square-discriminant analysis (PLS-DA) model resulting in a misclassification error rate of 0.024. Finally, network analysis of the 66 ions showed disregulation of amino acid metabolism in the gastric cancer tissues. The results show that the proposed framework was effective in analyzing TOF-SIMS data from a moderately large size of samples, resulting in discrimination of gastric cancer tissues from normal tissues and identification of biomarker candidates associated with the amino acid metabolism.</P>