• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.64-75
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• 1991

The design of structures of modern industry has developed to satisfy stringent service, realiability and safety. Up to now, geometric profile which means surface foughness and dimension accuracy is mainly treated in manufacturing process of work surface. But it is inevitable to evaluate changes of surface geometry as well as the nature of alterations in surface layers because surface of workpiece changes as a result of phase transformation, chemical changes, plastic deformation and stress changes. This paper is to present principal data for safety design by verifying the effect of grinding conditions and method in grinding layers and to explain the method of measuring surface integrity. In this paper, structural steel(SM20C) is used as a workpiece. Of integrity, surface roughness in view of surface texture is analyzed by frequency domain and residual stress, structures and defect of ground layers in view of surface metallurgy are investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.36-46
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• 1995

In this paper, fatigue crack propagation behaviors were investigated experimentally for the materials, carbon steel forgings (SF45A, SF50A, SF60A) which are used in the marine propeller shaft. The results obtained are as follows: The number of cycles required to grow crack length 1.30mm from microcrack initiation was about 60% of the total fatigue life. Fatigue crack propagation rate was expressed by the equation d(2a)/dN_B 2a/$N_f$ and the result was agreed well with the experimented data. And the equation d(2a)/dN=$C{\sigma}_a^m(2a)^n$ was evaluated also. Obtained material property m and n are 3~5 and 1-1.5 respectably, and the result was reasonably agreed to the data obtained from experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.731-739
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• 2006

Corrosion and lassitude are very important in the metal construction Currently, the shot peening is used much for removing the defect on the surface, improving the fatigue strength on surface. In this study. the influence of shot peening to the corrosion property were investigated in 3.5% NaCl, 10% HNO3 + 3% HF. 6% FeC13. The immersion test was performed on two kind of specimen(Removed corrosion product. RCP and Continuous immersed specimen: CIS). The immersion periods was 3600hours. Corrosion potential. weight loss, and fatigue crack growth characteristics were investigated. The result, shot peening in corrosion potential showed stable potential. Also, shot peening displayed small Weight loss than un peening. And Fatigue crack resistivity of shot peening in corrosion solution's fatigue crack appeared greatly than un peening.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.546-551
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• 1997

In sheet metal forming, since the surface area of workpiece is apparently larger than the volume of it, the surface condition of the sheet metal is much varied. The formability of sheet metal is decided by the forming limit and the macroscopic suface defect as like fracture and wrinkle, and microscopic asponent, The factors affected in forming limit are stain herdening exponent, strain-rate scnsitivity exponent, anisotropic coefficient. The increasing of surface roughness is decresed the forming limit curve. It is known that the greater plastic deformation the more surface roughness by Kienzle, Osadaka. The purpose of this study is to investigate the influences of surface roughness in a uniaxial tension and the traperzoidal-shaped box drawing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1113-1116
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• 2003

In this paper, it is suggested that the technology sound measurement which is to search the inferiority of the plate during the pressing. We evaluate whether there is a inferiority by analysing and comparing the satisfactory and inferior plate with the method of a spectrum analysis by measuring the sound which is emitted during pressing. We designed the analysis algorithm to detect inferior plate throughout comparison of measured sound data using FFT, DFT and DASYLab S/W. In addition to these, we suggest the way to compare both inferior and satisfactory signal statistically.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.92-99
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• 2003

Quality inspection of textile products is an important problem for fabric manufacturers. This paper presents an automatic vision-based system for quality control of web textile fabrics. Typical web material is 1-3m wide and is driven with speeds ranging from 20m/min to 200m/min. At the present, the quality assessment procedures are performed manually by expert. But worker can not detect more than 60％ of the present defect and inspect the fabric if moving faster than 30m/min. To increase the overall quality and homogeneity of textile, an automated visual inspection system is needed fur the productivity. However, the existing inspection system are too expensive to purchase for small companies. In this paper, the proposed PC based real-time inspection algorithm gives low cost textile inspection system, high detection rate with good accuracy and low rate of false alarms. The method shows good results in the detection of several types of fabric defects.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.307-310
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• 1995

In the conventional systems, a human must have knowledge of machines and of their special language in communicating with machines. In one side, it is desirable for a human but in another side, it is true that achieving it is very elaborate and is also a significant cause of human error. To reduce this sort of human load, an intelligent man-machine interface is desirable to exist between a human operator and machines to be operated. In the ordinary human communication, not only linguistic information but also visual information is effective, compensating for each others defect. From this viewpoint, problem of translating verbal expressions to some visual image is discussed here in this paper. The location relation between any two objects in a visual scene is a key in translating verbal information to visual information, as is the case in Fig.l. The present translation system advances in knowledge with experience. It consists of Japanese Language processing, image processing, and Japanese-scene translation functions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.381-388
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• 2006

A porous medium is composed of solids, fluids, and gas which have different physical and chemical properties. In addition, these constituents have a relative velocity between each other. So far, in order to analyze porous media using finite element method, Lagrangian or Eulerian method has been used. However, the numerical analyses for porous media have a defect that the methods do not describe the movements of constituents. In this paper, numerical analysis for unsaturated porous media was performed in frame of ALE method which has advantages of Lagrangian and Eulerian. Namely, the Lagrangian description was used in solid phase, and the Eulerian description was used in fluid or gas phase in a porous medium Then the relationship between each other was controlled by the convective term in ALE method. Finally, the numerical results of ALE were compared with tile results of Lagrangian analysis.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.2
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• pp.83-90
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• 2005

Failure cause of the fractured engine parts was analyzed by microstructural observation. These parts were failed far earlier than the expected service life. By the stereoscope and SEM examinations of the fractured surface, the fracture modes have been identified as wear and fatigue failure. From the observation of microstructure and microhardness measurements of the failed gears, the probable cause for failures are internal oxidation during using and retained austenite and carbide networks due to heat-treatment, respectively. These defected structures at near surface contributed to the wear and fatigue failure.

• Journal of Korean Society for Quality Management
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• v.22 no.4
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• pp.13-27
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• 1994

This study is concerned with design of EWMA control charts for counted data. Control charts for the fraction defective and the number of defects are designed. Performance analysis is accomplished for validity of the designed EWMA control charts. Average run length(ARL) is adopted as a criterion for comparison. Simulation results show that the designed EWMA control charts have shorter ARL than pn, p and c control charts when the fraction nonconforming or the average defect number are shifted. This means that the designed control charts can detect the out of -control state of the process more fastly than the traditional control charts.