• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.4
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• pp.347-355
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• 2013

A damage estimation method for monopile support structure of offshore wind turbine using modal properties and committee of neural networks is presented for effective structural health monitoring. An analytical model for a monopile support structure is established, and the natural frequencies, mode shapes, and mode shape slopes for the support structure are calculated considering soil condition and added mass. The input to the neural networks consists of the modal properties and the output is composed of the stiffness indices of the support structure. Multiple neural networks are constructed and each individual network is trained independently with different initial synaptic weights. Then, the estimated stiffness indices from different neural networks are averaged. Ten damage cases are estimated using the proposed method, and the identified damage locations and severities agree reasonably well with the exact values. The accuracy of the estimation can be improved by applying the committee of neural networks which is a statistical approach averaging the damage indices in the functional space.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.69-81
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• 2003

Numerical analysis is important for the design, construction and maintenance of large caverns. The rock mass contains generally discontinuities such as faults, joints and fissures. The mechanical behavior and geometric characteristics of these discontinuities would have a significant impact on the stability of the caverns. In this research the Distinct Element Method(DEM) was used to analyze the structural stability of the large cavern. The Barton-Bandis Joint Model (B-B J.M) was used as a constitutive model for the joint. In addition, two different cases 1) analysis with a support system and 2) analysis with no support system, were analyzed to optimize a support system and to investigate reinforcing effects of a support system. The most significant parameters of in-situ stress, JRC of in-situ natural joints, and spatial distribution characteristics of discontinuities were acquired through field investigation. Displacement (horizontal, joint shear), maximum joint opening, maximum and minimum principal stresses, range of relaxed zone, rockbolt axial forces and shotcrete stresses were calculated at each excavation stage. As a result of analysis the calculated values proved to be under the allowable value Rockbolts also proved to be an efficient support measure to control joint shear displacement which had significant effects on extending the relaxed zone. As a consequence, the structural stability of the cavern was assured with an appropriate support system.

• Journal of Korean Association for Spatial Structures
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• v.13 no.4
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• pp.57-66
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• 2013

Spatial structures have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and seismic response for seismic design of spatial structure. Keel arch structure is used as an example structure because it has primary characteristics of spatial structures. In case of spatial structures with different ground condition and time lag, multiple support excitation may be subjected to supports of a keel arch structure. In this study, the response of the keel arch structure under multiple support excitation and with time lag are analyzed by means of the pseudo excitation method. Pseudo excitation method shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. It is known that the seismic responses of spatial structure under multiple support excitation are different from those of spatial structure under simple excitation. And the seismic response of spatial structure with time lag are different from those of spatial structure without time lag. Therefore, it has to be necessary to analyze the seismic response of spatial structure under multiple support excitation and time lag because the spatial structure supports may be different and very long span. It is shown that the seismic response of spatial structure under multiple support seismic excitation are different from those of spatial structure under unique excitation.

• Structural Engineering and Mechanics
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• v.62 no.2
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• pp.247-258
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• 2017

Beam-like structures such as bridge, high building and tower, pipes, flexible connecting rods and some robotic manipulators are often excited by support motions. These structures are important in machines and structures. So, this study proposes an analytic method to accurately predict the dynamic behaviors of the structures during support motions or an earthquake. Using Timoshenko beam theory which is valid even for non-slender beams and for high-frequency responses, the analytic responses of fixed-fixed beams subjected to a real seismic motions at supports are illustrated to show the principled approach to the proposed method. The responses of a slender beam obtained by using Timoshenko beam theory are compared with the solutions based on Euler-Bernoulli beam theory to validate the correctness of the proposed method. The dynamic analysis for the fixed-fixed beam subjected to support motions gives useful information to develop an understanding of the structural behavior of the beam. The bending moment and the shear force of a slender beam are governed by dynamic components while those of a stocky beam are governed by static components. Especially, the maximal magnitudes of the bending moment and the shear force of the thick beam are proportional to the difference of support displacements and they are influenced by the seismic wave velocity.

• Journal of Korean Academy of Nursing
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• v.43 no.1
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• pp.81-90
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• 2013

Purpose: This study was done to test structural equation modeling of health-related quality of life (QOL) of men with obstructive sleep apnea in order to identify parameters affecting QOL and provide guidelines for interventions and strategies to improve QOL in these patients. Methods: Model construction was based on 'The conceptual model of patient outcome in health-related QOL' by Wilson and Cleary, using the variables; age, physiological factors, social support, cognitive appraisal, symptoms and QOL. Participants were 201 adult male patients recruited at a tertiary university hospital in Seoul. Data were collected via questionnaires, polysomnography, and clinical records. Results: Age and symptoms directly influenced QOL. Social support and cognitive appraisal about sleep did not have a direct influence on QOL, but indirectly affected it via symptoms. QOL was lower in patients who were younger and had more severe symptoms. Symptoms were more severe for patients with lower social support and more dysfunctional cognitive appraisal. When social support was lower, cognitive appraisal was more dysfunctional. Conclusion: These results suggest it is necessary to not only manage symptoms, but also apply interventions to increase social support and cognitive appraisal about sleep in order to increase QOL in patients with obstructive sleep apnea.

• Research in Community and Public Health Nursing
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• v.18 no.4
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• pp.624-633
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• 2007

Purpose: The purpose of this study was to develop and test a structural model on work-related musculoskeletal disorders of women workers. Method: Data were collected from 237 women workers from industries such as electronics, food production and garment production, and analyzed by LISREL 8.54. Result: The fitness indices of the model are GFI=.87, NNFI=.91, PNFI= .74. Eight out of the ten paths were proved to be statistically significant: work environment$\rightarrow$social support, work environment$\rightarrow$health behavior, work environment$\rightarrow$-WMSDs, domestic work$\rightarrow$health behavior, social support$\rightarrow$health behavior, social support$\rightarrow$job satisfaction, health behavior$\rightarrow$job satisfaction, and job satisfaction$\rightarrow$WMSDs. Work environment. social support, health behavior and job satisfaction significantly influenced WRMDs. WRMDs were accounted for 35% by the predictor variables. Conclusion: In conclusion, this study identifies that work environment, social support, health behavior and job satisfaction are important factors affecting WMSDs. Therefore, in order to prevent WRMDs, it is most important to improve both physical work environment for female workers such as appropriate work station and tools fit for them and psychological environment such as less job demand and more decision latitude(worker control).

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.59-62
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• 2011

Among the accidents and failures that occur during concrete construction, many are formwork failures which usually happen when concrete is being placed. A system of formwork filled with wet concrete has its weight at the top and is not basically a stable structure. Slab formwork consists of sheathing, stringer, hanger and shore. There are several types of adjustable shores. In construction site, pipe supports are usually used as a shore of slab formwork. In this study, pipe support systems with/without horizontal connector were measured by buckling test. Buckling load of respective pipe support system was analyzed by structural analysis program(MIDAS). Buckling load of pipe support with/without horizontal connector was got by test and structural analysis. According to these results, we know that horizontal connector made pipe support system very safe. Buckling load of pipe support with horizontal connector is 56% higher than that without horizontal connector. So horizontal connector is important in slab formwork systems. Finally, the present study results will be used to design slab formwork system safely in the construction sites.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.187-199
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• 2019

In the case of gas carriers and oil tankers, pipes are installed on the upper deck as a moving passage to load LPG, LNG, crude oil, etc. Pipes used for loading or unloading liquid cargo in cargo holds are connected to the hull through support structures. However, many cases of hull damage have been reported where the various equipment and support structures are installed on the upper deck. It is assumed that not only the structural discontinuity where the hull and the pipe support structure meet, but also action due to the pipe loads and the hull girder bending moment are simultaneously affected. This paper deals with the design and strength evaluation of the support structure of pipes and cables installed on the upper deck of commercial ships and offshore structures. For these supporting structures, design conditions and working loads were defined. The design procedure was established through the structure analysis on the method of determining the member dimensions. A series of finite element analysis was performed on the factors to be considered in the design and the effects were discussed. The accuracy and design periods of the strength evaluation was improved and reduced by application of the automation program in the finite element analysis. It is also expected that the design reliability of the shipyard is improved.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.127-135
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• 2021

This study aims to examine the impact of accessing industrial factors in enhancing business performance with special reference to Muslim women entrepreneurs in Sri Lanka. Industrial factors are industrial resources available to Muslim women entrepreneurs in Sri Lanka and it was measured using the dimensions of resource accessibility and government and non-governmental support. A structured questionnaire was used to collect data from 260 women entrepreneurs from the Muslim community who are registered with the chamber of commerce in the three districts of the Eastern province of Sri Lanka, using a simple random sampling technique. Structural Equation Modeling with AMOS was used as the data analysis technique. The structural model showed that resource accessibility had a significant and positive relationship with business performance, whereas government and non-governmental support did not significantly influence business performance. Especially, Muslim women entrepreneurs in Sri Lanka do not show interest in getting support such as finance, training, and other necessities from government and non-government organizations as well as business development support agencies. Trade chambers and decision-making authorities may use this finding to gain insights and develop strategies to enhance the business performance of women entrepreneurs.

• Computational Structural Engineering
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• v.22 no.5
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• pp.59-63
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• 2009