• Journal of the Korea institute for structural maintenance and inspection
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• v.1 no.2
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• pp.107-113
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• 1997

Nondesructive test and structural analysis have been conducted to assess the safety of weld defective steel bridges in service. In the nondestructive test, using the radioactive ray and ultrasonic, the defective welding patterns in the steel bridges are identified. A major defective welding pattern is identified as the lack of welding area due to the insufficient welding penetration. By considering the welding defect in the above, structural analysis is conducted to evaluate the influence of welding defect on the safety of steel bridges. The results indicate that, due to the insufficient welding penetration, the stress obtained in the analysis is over the allowable fatigue stress level, and its influence on safety of the bridges is significant.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.1
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• pp.62-71
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• 2011

There is widespread concern that particulate filtering respirators (PFRs) available in Korea will be efficient for nanoparticles. The purpose of this review study was to analyse research literature and recommend PFRs suitable for protection against nanoparticles. In all studies, respirators containing electret filter media (N95, P100 and FFP2, FFP3) consistently have their MPPS below 100 nm and particle penetration levels at the MPPS can vary widely, but they comply with NIOSH or EN certification criterion. Electret filtering facepieces respirators (FFRs) were found to shift in the Most-Penetrating Particle Size(MPPS) from 30-60 to 200-300 nm range after the electric charges were removed, and FFRs were above their minimum penetrations of criterion. Korean special class and first class FFRs (the same as FFP3 and FFP2, respectively) would be effcient for nanoparticles unless FFRs are removed electric charges. It is difficult to evaluate if mechanical PFRs is efficient for nanoparticles due to the lack of related materials.

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.142-144
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• 1996

This paper discusses the application of infra-red thermography in monitoring the robotic arc welding process, and it's potential for weld bead dimension and seam tracking control. Thermal images illustrating weld pool formation dynamics and heat distribution phenomena are digitized and their characteristics are measured. At each sampling point the maximum depth of penetration is recorded together with additional information regarding weld bead placement in relation to the seam location. Deficiencies such as incomplete penetration and lack of side wall fusion are readily identified and can be remained during the process. The technique can help an increase in productivity and weld quality by minimizing the amount of post process rework and inspection efforts needed otherwise.

• Asia pacific journal of information systems
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• v.13 no.4
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• pp.49-72
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• 2003

Despite the phenomenal growth of Internet users in recent years, the penetration rate of B2C electronic commerce(EC) is still low. According to previous studies, one of most often cited reasons is the lack of consumers' trust. Although trust is an important concept in B2C EC, there is a lack of theory-based empirical research in this area. In this paper, influencing factors are proposed for investigating the nature of trust in the specific context of B2C EC. Thirteen hypotheses are empirically tested. The results show that most of hypotheses are supported except for perceived size, perceived competence, perceived reputation, familiarity and third party recognition. In addition trust was found to have a strong positive effect on intention to purchase. Finally, trust was found to have a mediation effect between on influencing factors and intention to purchase. Implications of these findings are discussed for researchers and practitioners.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.119-127
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• 2000

In this study the classified researches the artificial and natural flaws in welding parts are performed using the pattern recognition technology. For this purpose the signal pattern recognition package including the user defined function was developed and the total procedure including the digital signal processing feature extraction feature selection and classifi-er selection is teated by bulk,. Specially it is composed with and discussed using the statistical classifier such as the linear discriminant function the empirical Bayesian classifier. Also the pattern recognition technology is applied to classifica-tion problem of natural flaw(i.e multiple classification problem-crack lack of penetration lack of fusion porosity and slag inclusion the planar and volumetric flaw classification problem), According to this result it is possible to acquire the recognition rate of 83% above even through it is different a little according to domain extracting the feature and the classifier.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.274-280
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• 1998

The welding technology and qualities are developed significantly, in recent years, in the use of automated processing technology and welding robot systems. But these automated welding technologies have many difficulties for finding the optimal welding parameter conditions. Because of the lack of mathematical model for determination of optimal welding process parameters. In this study, the sensitivity analysis of the empirical equations for finding weld bead width, height and penetration depth by using the published formulae. The selected major welding process parameters effected to weld bead geometries are the welding speed, current, voltage and weld wire diameter.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.437-442
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• 1986

Survey has been made to evaluate technological level and to identify research issues in CAD/CAM area. It is found out that major users of the CAD/CAM system are in mechanical and electronics as well as garment industries. Their experience shows that the impact of the CAD/CAM introduction is not yet noticeable in drafting man power and cost reduction. It is identified that the low penetration rate of CAD/CAM technology in industry is due to the lack of locally developed CAD/CAM softwares.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.4
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• pp.577-586
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• 1993

Pesticide protective clothing has not been frequently worn due to its lack of thermal comfort. It is important to develop fabrics which can allow the wearer to work in comfort. One of the possible way to achieve the goal is to produce fabrics with a water- and oil-repellent finish which would resist pesticide penetration but maintain some breathability. The purpose of this study were to evaluate the pesticide barrier properties of untreated and water- and oil-repellent finished nonwoven fabrics. Three types of nonwoven fabrics(Tyvek, Sontara and Kimlon) were used as test specimens. By pad-dry-cure method, each of the specimen was treated with fluorocarbon. The pesticide barrier properties (amount of pesticide penetration and residue) were measured by the gas chromatography. The performance properties of untreated and treated specimens were evaluated with respects to water pepellency(KS K 0590), oil repellency(AATCC 118), water resistance(KS K 0591, AATCC 42), water vapor transmission (KS A 1013) and air permeability(KS K 0570). The results of this study were as follows : 1) The untreated Sontara showed much more amount of pesticide penetration than untreated Tyvek and Kimlon, while the treated Sontara showed little amount of pesticide penetration. 2) After laundering, the amount of pesticide residue in the untreated and treated Sontara was less than that in Tyvek and in Kimlon. 3) Water- and oil-repellent finish improved water repellency, oil repellency, and water resistance of specimens. 4) The untreated Sontara and Kimlon showed higher water vapor transmission and air permeability than untreated Tyvek. Water vapor transmission and air permeability of treated specimen decreased compared to those of untreated.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.29-34
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• 2012

Investigating safer ways to design and use to prevent a loss of life and property by failure of the structures are necessary and assessing total fatigue life with initiation and propagation of fatigue crack accurately through fatigue analysis is very important. The object of this study is to examine the initial life and propagation life when the fatigue crack is introduced from the root which is likely to appear in LOP(Lack of Penetration) cruciform fillet welded structure including bridges, ships and gas storage facilities which are impossible to be fully penetrated and to measure the rate of fatigue life until the final cleavage failure. As the result, each rate of fatigue life for fatigue failure is somewhat different in the range of 5% according to the thickness of material, however, the overall rate of initial life is in the range of 34~39% and propagation life showed the range of 61~66%.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.4
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• pp.323-330
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• 2008

High cycle bending fatigue of socket welded small bore pipe was characterized, and also the fatigue crack initiation of small bore pipe was monitored in situ by the acoustic emission (AE) technique. The STS 316L stainless steel specimens were prepared by gas tungsten arc welding (GTAW) process having the artificial defect (i.e., lack of penetration) and defect free at the root. The fatigue failure was occurred at the loc for high stress and root for relatively low stress. The crack initiation cycles ($N_i$) was defined to the abrupt increase in AE counts during the fatigue test, and then the cracks were observed by the radiographic test and electron microscope before and after the fatigue crack initiation cycles. The socket welded pipe damaged by bending fatigue was studied regarding the welding defect, failure mode, and crack initiation cycles for the diagnosis and monitoring.