• Advances in aircraft and spacecraft science
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• v.4 no.5
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• pp.515-528
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• 2017

Since composite structures are widely used in structural engineering, delamination in such structures is an important issue of research. Delamination is one of a principal cause of failure in composites. In This study the electrical potential (EP) technique is applied to detect and locate delamination in basalt fiber reinforced polymer (FRP) laminate composite pipe by using electrical capacitance sensor (ECS). The proposed EP method is able to identify and localize hidden delamination inside composite layers without overlapping with other method data accumulated to achieve an overall identification of the delamination location/size in a composite, with high accuracy, easy and low-cost. Twelve electrodes are mounted on the outer surface of the pipe. Afterwards, the delamination is introduced into between the three layers (0º/90º/0º)s laminates pipe, split into twelve scenarios. The dielectric properties change in basalt FRP pipe is measured before and after delamination occurred using arrays of electrical contacts and the variation in capacitance values, capacitance change and node potential distribution are analyzed. Using these changes in electrical potential due to delamination, a finite element simulation model for delamination location/size detection is generated by ANSYS and MATLAB, which are combined to simulate sensor characteristic. Response surfaces method (RSM) are adopted as a tool for solving inverse problems to estimate delamination location/size from the measured electrical potential changes of all segments between electrodes. The results show good convergence between the finite element model (FEM) and estimated results. Also the results indicate that the proposed method successfully assesses the delamination location/size for basalt FRP laminate composite pipes. The illustrated results are in excellent agreement with the experimental results available in the literature, thus validating the accuracy and reliability of the proposed technique.

• Structural Engineering and Mechanics
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• v.20 no.5
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• pp.505-526
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• 2005

The influence of the inter-story structural pounding on the seismic behaviour of adjacent multistory reinforced concrete structures with unequal total heights and different story heights is investigated. Although inter-story pounding is a common case in practice, it has not been studied before in the literature as far as the authors are aware. Fifty two pounding cases, each one for two different seismic excitations, are examined. From the results it can be deduced that: (i) The most important issue in the inter-story pounding is the local effect on the external column of the tall building that suffers the impact from the upper floor slab of the adjacent shorter structure. (ii) The ductility demands for this column are increased comparing with the ones without the pounding effect. In the cases that the two buildings are in contact these demands appear to be critical since they are higher than the available ductility values. In the cases that there is a small distance between the interacting buildings the ductility demands of this column are also higher than the ones of the same column without the pounding effect but they appear to be lower than the available ductility values. (iii) It has to be stressed that in all the examined cases the developed shear forces of this column exceeded the shear strength. Thus, it can be concluded that in inter-story pounding cases the column that suffers the impact is always in a critical condition due to shear action and, furthermore, in the cases that the two structures are in contact from the beginning this column appears to be critical due to high ductility demands as well. The consequences of the impact can be very severe for the integrity of the column and may be a primary cause for the initiation of the collapse of the structure. This means that special measures have to be taken in the design process first for the critically increased shear demands and secondly for the high ductility demands.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.29-35
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• 2017

The fourth industrial revolution and so on, the manufacturing environment is based on the latest IT technology, and ICT-based convergence that links with various industrial fields is actively proceeding. For this reason, convergence security based on changing environment in the field of security is emerging as a new issue, and various demands for convergence security are increasing. Such changes in the industrial environment not only provide advantages of convergence environment, but also cause various fusion and complex security problems. In particular, the government is actively promoting policies to build 10,000 smart plants by 2020, and has implemented projects to build 2,800 smart plants from 2014 to 2016. Therefore, we will examine the security threats and countermeasures against smart factories that are being built on the basis of ICT rather than the existing closed type.

• Journal of the Korean Data and Information Science Society
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• v.26 no.1
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• pp.101-109
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• 2015

SMRs (standardized mortality rates) for major diseases, accidents, cancer are considered in small areas of administrative units such as Eup/Myeon/Dong from years 2005 to 2008. Due to small sample issue in small areas, the precision of directly estimated crude SMR for each area can be low. In this study, we consider the HGLM (hierarchical generalized linear model) with MRF (Markov random field) to account for the spatial correlations among the small areas. The effects of covariates for cause of mortality by Dongs in Seoul and disease maps based on the estimated SMR are presented. The results suggest how we analyze and interpret the difference in mortalities by small areas such as Dongs by revealing the spatial patterns.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.2
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• pp.289-297
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• 1997

Work-related low back pain(below LBP) is one of the major cause of morbidity, disability, limitation of activity and economic loss. Therefore the work-related LBP is one of the major issue in the field of industrial safety and health. This study was performed for detecting the risk factors and proposing the effective control programs of work-related LBP. The subjects were male workers employed at the welding and metal factory. The data was collected by self-reported questionnaire, interview and checking abdomen muscular and grasping power for two days on October, 1993. The contents of questionnaire were as follow: the experience of LBP, general characteristics, physical characteristics, employment status, type of work and working environment. The number of cases was 104 with a history of work-related LBP, so the prevalence of work-related LBP was 35.0%, and the number of controls was 140 without any history of LBP. As a result, marital status, educational level, abdomen muscular power, tenure, category of job, satisfaction of job, working posture, satisfaction for table and chair and lifting materials showed a statistical significance between the case and control groups. 284 Lifting jobs were quantified by NIOSH lifting equation method and ergonomic computer modelling methods. There were no significant differences in the action limit and disc compression force between group with LBP and without LBP. But in the lifting frequency and cumulative disc compression force there were significant differences. Therefore work-related LBP should be prevented by the ergonomic and environmental control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.947-950
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• 2015

In the cause of car accidents in Korea, drowsy driving has shown that it is larger fctors than drunk driving. Therefore, in order to prevent drowsy driving accidents, drowsiness detection and warning system for drivers has recently become a very important issue. Furthermore, Many researches have been published that measuring alpha wave of EEG signals is the effective way in order to be aware of drowsiness of drivers. In this study, we have developed EEG measuring device that applies a signal processing algorithm using the LabView program for detecting drowsiness. According to results of drowsiness inducement experiments for small test subjects, it was able to detect the pattern of EEG, which means drowsy state based on the changing of power spectrum, counterpart of alpha wave. After all, Comparing to the results of drowsiness pattern between commercial equipments and developed device, we could confirm acquiring similar pattern to drowsiness pattern. With this results, the driver's drowsiness prevention system expect that it will be able to contribute to lowering the death rate caused by drowsy driving accidents.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.379-385
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• 2003

In the existing method to design geosynthetic reinforced embankment, the required strength of reinforcements is determined by vertical stress only rather than strain. This strength is not in accord with tensile strength that behaves as reinforcement in earth structures. The reinforcement and adjacent soil on the failure plan behave in one unit at the initial stress phase but they make a gap in strain as stress increases. This issue may cause a big impact as a critical factor on geosynthetic reinforcement design in earth structures. The quantitative analysis on strain behavior was performed with a PET Mat reinforced embankment on soft ground. From this study, several outstanding discussions are found that tensile strength of reinforcement governs the failure of embankment when the soil stress is greater than failure stress. Also the optimum required tensile strength of geosynthetic reinforcement(Tos) should be determined by stress, displacement, displacement gap and safety factor of soil-PET Mat at the location of PET Mat.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.11a
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• pp.437-441
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• 2008

The community mixed-support facility in Japan is making efforts to try various approaches according to the changes made to allow the privatization of public facilities on the basis of Act on Special Measures for Urban Regeneration since 2004. Due to this change in policy, the community mixed-support facility is now taking further steps in trying to implement variety of approaches in the perspective of urban regeneration and urban maintenance and at the same time the trend of installation of community facility has gone through vivid changes for the last 20 years. The causes of this are from the social demand that claims for of new facilities and the change in the subsidy system in relation to equality in facility installation. Examples of the first cause can be the building of perpetuating educational society, an execution or a movement towards the society of gender equality, a countermovement for an aging society as well as a welfare society, and recently social phenomenon related to consumption is becoming an issue. And for the last, the number of construction of facilities is increasing that grow out of the traditional facility system. The complex of community mixed-support facility will provide public administrative and community mixed-support services to local people as well as to form a notion of community and a feeling of solidarity. Ultimately, this will develop local areas by regional interchanging of information. In this very research, we will analyze the community mixed-support facility and its characteristics as well as its implications and consider the types of complex through many preceding instances in Japanese community mixed-support facility.

• Particle and aerosol research
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• v.12 no.3
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• pp.51-56
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• 2016

Due to recent development in nanotechnology and increasing usage and production of nanomaterials, numerous studies related to environment, sanitation and safety handling of nanoparticle are being conducted. Since nanoparticles can be easily absorbed into human bodies through breathing process, based on their toxic substances and their large specific surface, these particles can cause serious health damage. Therefore, to reduce nanoparticle emissions, nanofiltration technology is becoming a serious issue. Filtration is a separation process during which a fluid passes through a barrier by removing the particles from the stream. Barrier filters can be made of various materials and shapes. One of the most common type of barrier filter is the fibrous filter. Fibrous filters are divided in two types: nonwoven and woven fabrics. Polypropylene is a thermoplastic material, used as a base material for melt blown nonwoven fabric. In this study, we examined filtration property of KCl nanoparticles with a mean particle diameter of 75 nm using multilayer meltblown filter samples. These experiments verify that the penetration of nanoparticle in the filter correlate with pressure drop; the meltblown layer MB1 has the greatest effect on dust collection efficiency of the filter. Among all tested samples, dust collection efficiency of 2-layer filter was best. However, when considering the overall pressure drop and dust collection efficiency, the 4-layer filter has the highest quality factor for particles smaller than 70 nm.

• Korean Journal of Biological Psychiatry
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• v.22 no.1
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• pp.1-6
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• 2015

Suicide, the fourth leading cause of death in Korea, is a serious national problem. The Korea National Suicide Survey (KNSS) is the result of the first legislation to address this issue, "Article 11 of THE ACT FOR THE PREVENTION OF SUICIDE AND THE CREATION OF A CULTURE OF RESPECT FOR LIFE" (the "Act for the Prevention of Suicide"). To overcome the limitations of previous studies, the KNSS was designed by collaborators from a variety of fields : psychology, epidemiology, social welfare, and psychiatry. The KNSS was composed of four substudies that addressed the multifaceted process involved in suicide-related behavior over time, exploring general attitudes toward suicide and suicidal ideation, suicide planning, suicide attempts, and completed suicides. Study 1 examined the risk factors for suicide based on data regarding completed suicides ; Study 2 adopted the approach of a psychological autopsy ; Study 3 focused on suicide attempters ; and Study 4 explored attitudes toward suicide in the general population. The KNSS was designed to provide a comprehensive understanding of suicide from a longitudinal, multifaceted perspective to serve as a basis for policies aimed at suicide prevention.