• Steel and Composite Structures
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• v.21 no.5
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• pp.1017-1029
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• 2016

When a welded circular hollow section (CHS) tubular joint is subjected to brace axial loading, failure position is located usually at the weld toe on the chord surface due to the weak flexural stiffness of the thin-walled chord. The failure mode is local yielding or buckling in most cases for a tubular joint subjected to axial load at the brace end. Especially when a cyclic axial load is applied, fracture failure at the weld toe may occur because both high stress concentration and welding residual stress along the brace/chord intersection cause the material in this region to become brittle. To improve the ductility as well as to increase the static strength, a tubular joint can be reinforced by increasing the chord thickness locally near the brace/chord intersection. Both experimental investigation and finite element analysis have been carried out to study the hysteretic behaviour of the reinforced tubular joint. In the experimental study, the hysteretic performance of two full-scale circular tubular T-joints subjected to cyclic load in the axial direction of the brace was investigated. The two specimens include a reinforced specimen by increasing the wall thickness of the chord locally at the brace/chord intersection and a corresponding un-reinforced specimen. The hysteretic loops are obtained from the measured load-displacement curves. Based on the hysteretic curves, it is found that the reinforced specimen is more ductile than the un-reinforced one because no fracture failure is observed after experiencing similar loading cycles. The area enclosed by the hysteretic curves of the reinforced specimen is much bigger, which shows that more energy can be dissipated by the reinforced specimen to indicate the advantage of the reinforcing method in resisting seismic action. Additionally, finite element analysis is carried out to study the effect of the thickness and the length of the reinforced chord segment on the hysteretic behaviour of CHS tubular T-joints. The optimized reinforcing method is recommended for design purposes.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.1
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• pp.95-100
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• 2007

In the steel & iron processing line, some characters are marked for the material management in the surface of material. This paper describes about the developed results of vision system for the recognition of material management characters, which was included in the slab image. Our vision system for the character recognition includes that CCD camera system which acquire slab image, optical transmission system which transmit captured image to the long distance, input and output system for the interface with existing system and monitoring system for the checking of recognition results. We have installed our vision system at the continuous casting line and tested. Also, we have performed inspection of durability, reliability and recognition rate. Through the testing, we have confirmed that our system have high recognition rate, 97.4%.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.2
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• pp.142-150
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• 2004

A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. The mode identification has been carried out in a pipe using the time-frequency analysis methods such as the wavelet transform(WT) and the short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural modes. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual modes. It was found out that the longitudinal mode(0,1) is less affected by mode conversion compared with the other modes. Therefore, L(0,1) is selected as an optimal mode for the evaluation of the surface defect in a pipe.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.2
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• pp.139-143
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• 2011

The problem of delamination of composite tubes by impact has been acknowledged in aerospace and automobile industry. Non-destructive testing(NDT) methods in composite material structure are important to evaluate reliability of composite structure. There are many kinds of NDT methods which can detect the inside defect of the composite material such as Infrared Thermography(IRT). Infrared thermal imaging of object is different from that of a defect, in heated composite tubes with an internal defect, and then location and size of a defect can be measured by the analysis of thermal imaging pattern. In this study, Lock-in Infrared thermography detect internal defects of Impacted composite tubes by the inspection of infrared lay radiated from the surface of composite tubes.

• 보존과학연구
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• s.26
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• pp.141-164
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• 2005

Most of the stone cultural properties is exposed to the weathering factor(rain, windetc.), so the shelter is constructed for reduction of its direct effect. But the shelter is indicated some problems that inharmoniousness of the surroundings, in section disturbance for insufficiency of light, the loss about the value of cultural properties and so on. So we have investigated on environmental condition (temperature, relative humidity, wind etc.) at the Standing Stone Buddhist Triad in Bae-ri, Gyeongju and Rock-carved Triad Buddha in Seosan because check the effect of the shelter. As the result, the Standing Stone Buddhist Triad in Bae-ri, Gyeongju is located a pine wood and a lot of bamboo grow naturally in nearing. Environmental difference on inside and outside of the shelter is not found because opened on all sides. But there is so dim for the direction of the sunlight that can't see the Standing Stone Buddhist. The base rock of Rock-carved Triad Buddha in Seosan well develop with crack and break, and the vegetation(trees, moss, lichen etc.) grow naturally in surroundings. Environmental difference on inside and outside of the shelter is found because closed on all sides and opened the front gate only inspection time. Inside of the shelter was too calm(air-velocity not detected) and humid(over 75%RH). Also the surface is occurred the dew(at 2-4 pm) and the efflorescence for effect of the water(rain, dew etc.). Besides the head of the central Buddhist is so dangerous for crack.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3106-3106
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• 2001

Imaging spectrometry or hyperspectral imaging is a recent development that makes possible quantitative and qualitative measurement for food quality and safety. This paper presents the research results that a hyperspectral imaging system can be used effectively for detecting fecal (from duodenum, cecum, and colon) and ingesta contamination on poultry carcasses from the different feed meals (wheat, mile, and corn with soybean) for poultry safety inspection. A hyperspectral imaging system has been developed and tested for the identification of fecal and ingesta surface contamination on poultry carcasses. Hypercube image data including both spectral and spatial domains between 430 and 900 nm were acquired from poultry carcasses with fecal and ingesta contamination. A transportable hyperspectral imaging system including fiber optically fabricated line lights, motorized lens control for line scans, and hypercube image data from contaminated carcasses with different feeds are presented. Calibration method of a hyperspectral imaging system is demonstrated using different lighting sources and reflectance panels. Principal Component and Minimum Noise Fraction transformations will be discussed to characterize hyperspectral images and further image processing algorithms such as image band ratio of dual-wavelength images and its histogram stretching with thresholding process will be demonstrated to identify fecal and ingesta materials on poultry carcasses. This algorithm could be further applied for real-time classification of fecal and ingesta contamination on poultry carcasses in the poultry processing line.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.98-105
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• 2001

The machining accuracy is affected by geometric, volumetric errors of the machine tools. To improve the product quality, we need to enhance the machining accuracy of the machine tools. To this point of view, measurement and inspection of finished part as error analysis of machine tools ahas been studied for last several decades. This paper suggests the enhancement method of machining accuracy for precision machining of high quality metal reflection mirror or optics lens, etc. In this paper, we study 1) the compensation of linear pitch error with NC controller compensation function using laser interferometer measurement, 2) the method for enhancing the accuracy of NC milling machining by modeling and compensation of volumetric error, 3) the spherical surface manufacturing by modeling and compensation of volumetric error of the machine tool, 4) the system development of OMM without detaching work piece from a bed of machine tool after working, 5) the generation of the finished part profile by OMM. Furthermore, the output of OMM is compared with that of CMM, and verified the feasibility of the measurement system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.806-813
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• 2018

The fracture of a turbine blade of aerospace engine is presented. Although there are a lot of causes and failure modes in blades, the main failure modes are two ways that fracture and fatigue. Degradation of blade material affects most failure modes. Total propagation of failure in this study specifies failure of fracture type. Some section appears fatigue mode. Especially since this study describes analysis of failure for blade in high temperature, it can be a case in point. Analysed blade is Ni super alloy. Investigations of blade are visual inspection, material, microstructure, high temperature stress rupture creep test, analysis and fracture surface, etc. The root cause for fracture was stress rupture due to abnormal thermal environment. Thermal property of Ni super alloy is excellent but if each chemical composition of alloys are different due to change mechanical properties, selection of material is very important.

• The Plant Pathology Journal
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• v.25 no.4
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• pp.429-432
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• 2009

An unreported disease of apricot was observed in orchards in Zhejiang province, China. Symptoms started as water soaked lesions on the fruit surface. Later, water-soaked areas developed and spread to the entire fruit, resulting in soft rot of the whole fruit. The causal organism isolated from symptomatic fruits was identified as Burkholderia cepacia based on its biochemical and physiological characteristics and confirmed by the cellular fatty acid composition and Biolog data as well as 16S rRNA gene sequence analysis. The bacterial isolates caused similar symptoms when inoculated onto fruits of apricot. In addition, European plum, Japanese plum, nectarine and kiwifruit were susceptible to the B. cepacia pathogen. However, the B. cepacia pathogen failed to cause any visible symptoms when it was inoculated onto 16 other fruits. This is the first report of a bacterial disease of apricot caused by B. cepacia in China.

• Journal of the Korean Society of Clothing and Textiles
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• v.13 no.1 s.29
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• pp.79-87
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• 1989

In the part 1 and 2, relations were found between fundmental mechanical properties and primary hand values, performance of Korean women's summer and fall & winter fabrics. In this paper, in order to investigate the hand values and mechanical properties such as tensile, shearing, bending, compression, surface and thickness & weight of the core-spun yarn woven fabrics for Korean folk clothes were measured by KES-F system. The experimental results are statistically analyzed in the aspects of the mechanical properties, their effects on the hand values, formation of weared clothes and transformation behavior. The correlation in the hand values are analyzed, too. Furthermore, there mechanical properties are discussed in comparison with those values for kimono fabrics. The main results are summarized as follows: 1. The core-spun yarn woven fabrics for Korean folk clothes have box-shaped silhouette based on higher bending rigidity and shear elasticity. 2. The core-spun yarn woven fabrics for Korean folk clothes are inferior to silk fabrics, superior to polyester fabrics in formation. 3. A drapability and wrinkle recovery of core-spun yarn woven fabrics for Korean folk clothes formation for weared clothes are inferior to polyester fabrics, superior to silk fabrics. 4. A primary factor of mechanical properties contribute to the hand values of core-spun yarn woven fabrics for Korean folk clothes are same as the Korean women's winter fabrics, except for flexibility with soft feeling. 5. As for the hand values of core-spun yarn woven fabrics for Korean folk clothes, stiffness, anti-drape stiffness are superior to those of polyester fabrics. And also, flexibility with soft feeling, scrooping feeling of core-spun yarn woven fabrics have greater values as compared with silk fabrics for Korean folk clothes.