• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1412-1422
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• 2016

Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.2000-2006
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• 2000

The enhancement of service life of damaged or cracked structures is currently major issue to the researchers and engineers. In order to improve the life of cracked aging aircraft structures, the repair technique which uses adhesively bonded boron/epoxy composite patches is being widely considered as a cost-effective and reliable method. This paper is to study the performance of the bonded composite patch repair of a plate containing an inclined central through-crack. A 3-dimensional finite element method having three layers to the cracked plate, composite patch and adhesive layer, is used to compute the stress intensity factor. In this paper, the reduction of stress intensity factors near the crack-tip are determined to evaluate the effects of various non-dimensional design parameter including composite patch thickness, and material properties of the composite patch and thickness of the adhesive layer, materials of patch etc., and the crack length, Finally, The problem of how to optimize the patch geometric configurations has been discussed.

• Journal of Korea Trade
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• v.25 no.6
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• pp.126-142
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• 2021

Purpose - This study discusses the effects of human capital in the formation of GVC linkages. We also investigate GVC intensity between Korea and ASEAN. Design/methodology - To solve the doubling-counting problem in evaluating comparative advantage, RCA has been re-computed using domestic value-added (henceforth RCA_VA) at the country-sector level instead of value of trade. The impact of human capital on GVC intensity was empirically analyzed by establishing a panel data set with four industries (ISIC Rev. 4) in eight ASEAN countries from 2005 to 2015 from OECD-TiVA and WDI. Findings - The empirical results show that human capital has a negative effect on GVC intensity in the agriculture and manufacture industries, while it has a positive effect in the service and information industries. The results do not mean that low human capital is a barrier and inefficient to GVC linkages. Low Value-added activities may be more profitable to some emerging countries. These findings suggest that it is important to accurately identify the competitive elements to increase gains from trade under the GVC. Also, it shows that comparative advantages can be misled by an RCA index evaluated in trade volume under the GVC. Originality/value - This study highlights the importance of human capital as a factor for the efficient formation of Global Value Chain (GVC). This study has different from the literature in analyzing the role of human capital in formation of linkage of the GVC. And we clarify the changing patterns of trade by removing the double-counting problem under the GVC.

• Korea Journal of Hospital Management
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• v.16 no.1
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• pp.101-123
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• 2011

In this study, we examined the effects of high-performance work system(HPWS) on healthcare staffs' patient orientation and perceived service quality. To investigate the causalities of the factors such as HPWS, patient orientation, and perceived service quality, we collected national wide samples of 721 healthcare staffs from 144 hospitals. We deployed reliability analysis(Cronbach ${\alpha}$) and confirmatory factor analysis(CFA) for the factors. With 4 proposed hypotheses, we fabricated a structural equation model with AMOS 7.0 and examined the validity of the hypotheses. Followed were findings of this study. First, the healthcare staffs' perceptions of HPWS in hospital settings were positively linked to the perceived service quality. Second, the intensity of HPWS also influenced the healthcare staffs' patient orientation. Third, the perceptions of patient orientation were positively linked to the perceptions of service quality. Fourth, HPWS were linked to healthcare staffs` perceptions of service quality both directly and indirectly through their perceptions of patient orientation. These findings implied that HPWS would be a way of survival in drastically changing hospital environments.

• Plant Journal
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• v.7 no.1
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• pp.40-48
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• 2011

This study shows the comparison between expected and actual capacity factors of a wind farm through wind resource analyzation. The expected capacity factor comes from an 'automatic weather system' run by the Korean national weather service and a 'meteorological mast' run by a project owner. Based on this comparison and analysis, the importance of meteorological mast micro-siting and selection of wind turbine class and type, will be studied along with presenting important implications for wind farm expansion and development.

• Management & Information Systems Review
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• v.28 no.2
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• pp.95-112
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• 2009

The paper investigates the determinants of firm's standardization activity in the Korean service industry. Standardization variables as dependent ones are standardization management at the firm level, domestic standardization activity, and international standardization activity. The independent variables include innovative activities(R&D intensity and patent application), firm size, export ratio, network, and firm's organization characteristics. We estimated the logistic regression model, using the data from 102 Korean service firms. The empirical findings are as follows. First, R&D intensity has a positive effect on international standardization activity, but not on the standardization management at the firm level and domestic standardization activity. Second, patent application has a negative effect on the standardization management at the firm level. Third, firm size doesn't have any influence on firms' standardization activities in the service sector. Fourth, the level of chief executive officer's interest on standardization is a very important factor in determining firms' efforts to participate standardization process, regardless of types of standardization activity.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1228-1236
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• 2001

In this study, CT specimens were prepared from ASTH A5l6 steel which was used for pressure vessel plates for moderate and lower temperature service. And we got the fellowing characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$ , $-30^{\circ}C$, $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ and $-120^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the Threshold stress intensity factor range ΔAKth in the early stage of fatigue crack growth (Region I) and stress intensity factor range $\DeltaK$ in the stable of fatigue crack growth (Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN-$\Delta$K in Region II that is, the fatigue clack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.525-539
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• 2014

Bonded composite-patch repair has been widely used to restore or extend the service life of damaged structures due to its effectiveness as a mechanical repair technique. In this paper using extended finite element method (XFEM), three-dimensional crack models are developed to examine the fracture behavior of centrally cracked aluminum plates repaired with single and double sided composite patches. Stress intensity factor (SIF) at the crack tip is used as the fracture criterion. In this regard, the effects of the crack lengths, patch materials, orientation of plies, adhesive and patch thickness are examined to estimate the SIF of the repaired plate and the repair performance. The obtained results show that composite patches have significant effect on reduction of the SIF at the crack tip. It is also proved that using double symmetric repair, in comparison to single one, reduces considerably SIF at the crack tip. Hence, the residual strength can be improved significantly as well as fatigue life of the structure. Investigation of ply orientation effects shows SIF increase as the ply orientation is changed from $0^{\circ}$ (perpendicular to the advancing crack) to $90^{\circ}$ (parallel to the crack line). However, the effectiveness of the ply orientation depends on the loading direction and the crack direction.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.78-83
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• 2000

In this study, CT specimens were prepared from AST SA516 Gr. 70 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at 25$^{\circ}C $, -60$^{\circ}C $, -80$^{\circ}C $ and -100$^{\circ}C $ and in the range of stress ratio of 0.05, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\delta} K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range $\delta $K in the stable of fatigue crack growth (Region II) were increased in proportion to descending temperature. It was assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN -$\delta $K in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN is rapid in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.220-223
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• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - ΔK in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.