• Ocean Systems Engineering
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• v.9 no.2
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• pp.191-218
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• 2019

The tower-platform interface and mooring system of floating offshore wind turbines (FOWTs) are some of the most critical components with significant influences on overall project costs. In addition to satisfying strength requirements, it is typical and vital to meet fatigue criteria for a service life of 25 years or more. Wind spectra characteristics considered in analysis can penalize fatigue designs, leading to unnecessary costs. The International Electrotechnical Commission (IEC, 2009) recommends the use of site-specific wind data (spectrum, turbulence intensity, etc.) in design of FOWTs, but for offshore sites it is often the case that such data is unavailable and land-based data are used as surrogates in design. For such scenarios, it is worth investigating whether such alternative approach is suitable and accurate, and understanding the consequence of the selection of wind spectral characteristics on fatigue design. This paper addresses the impact of the subsequent selection on fatigue responses of towerbase and mooring system in a FOWT, as a sequel to the paper by Udoh and Zou (2018) which focused on impacts on strength design. The 5 MW semi-submersible FOWT platform with six mooring lines implemented in the preceding study is applied in analysis. Results indicate significant variations in resulting fatigue life with considered wind parameters. Thus, it is critical to apply proper wind spectra characteristics for analysis and design of FOWTs to avoid unnecessary conservatism and costs. Based on the findings of this study, more explicit guidance on the application of turbulence intensities for IEC-recommended models in offshore sites could lead to more accurate load estimates in design of FOWTs.

• Journal of Ecology and Environment
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• v.47 no.4
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• pp.219-227
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• 2023

The US National Science Foundation's National Ecological Observatory Network (NEON) is a continental-scale program intended to provide open data, samples, and infrastructure to understand changing ecosystems for a period of 30 years. NEON collects co-located measurements of drivers of environmental change and biological responses, using standardized methods at 81 field sites to systematically sample variability and trends to enable inferences at regional to continental scales. Alongside key atmospheric and environmental variables, NEON measures the biodiversity of many taxa, including microbes, plants, and animals, and collects samples from these organisms for long-term archiving and research use. Here we review the composition and use of NEON resources to date as a whole and specific to biodiversity as an exemplar of the potential of national research infrastructure to contribute to globally relevant outcomes. Since NEON initiated full operations in 2019, NEON has produced, on average, 1.4 M records and over 32 TB of data per year across more than 180 data products, with 85 products that include taxonomic or other organismal information relevant to biodiversity science. NEON has also collected and curated more than 503,000 samples and specimens spanning all taxonomic domains of life, with up to 100,000 more to be added annually. Various metrics of use, including web portal visitation, data download and sample use requests, and scientific publications, reveal substantial interest from the global community in NEON. More than 47,000 unique IP addresses from around the world visit NEON's web portals each month, requesting on average 1.8 TB of data, and over 200 researchers have engaged in sample use requests from the NEON Biorepository. Through its many global partnerships, particularly with the Global Biodiversity Information Facility, NEON resources have been used in more than 900 scientific publications to date, with many using biodiversity data and samples. These outcomes demonstrate that the data and samples provided by NEON, situated in a broader network of national research infrastructures, are critical to scientists, conservation practitioners, and policy makers. They enable effective approaches to meeting global targets, such as those captured in the Kunming-Montreal Global Biodiversity Framework.

• Korean Journal of Human Ecology
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• v.18 no.1
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• pp.1-12
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• 2009

The purpose of this study is to find out leisure constraints of the elderly and to examine how these constraints influence their participation in leisure activities and life satisfaction. The data analysis of 291 senior citizens over 60 years old were conducted, the research results are as follows: first, leisure constraints of senior citizens stem from individual, societal, economic, family constraints. It indicates that anyone of constraints did not exclusively determine leisure constraints. Rather, the result implies that leisure constraints for the elderly is from multifaceted levels of social system. Second, participation in leisure activities positively worked on life satisfaction. Third, leisure constraints of the elderly directly influenced their participation in leisure activities and life satisfaction. In conclusion, to revitalize senior citizens' participation in leisure activities is critical in advancing their life satisfaction. Nationwide positive and supportive social environment for their leisure participation should be established first, on which social and legal systems should be consequently organized. At the same time, social supports to provide opportunities for their leisure participation are required for the future senior citizens.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.7-13
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• 2011

RAMS is the procedure to maximize the reliability and availability of systems with managing operation rate, the frequency of failure in the system and repair method. Recently, all system life-cycle focusing on RAMS process has been rapidly developing in the field of railway vehicles, for example, applying th reliability management techniques for procurement and disposal of EMU. In particular, global economic recession require to reasonable measures for the EMU maintenance costs under the circumstances therefore, an alternative solution based on RCM(Reliability Centered Maintenance) which is the optimal maintenance method is interested. In this study, the state of being critical of each component and a primary factors was analyzed to improve VVVF inverter of the line 7 EMU by applying FMECA process. Furthermore, this paper showed the impact of connecting between the main and sub system. Based on these data, critical components according to malfunction ratings were classified by screening measures and improvements for each components was summarized.

• Review of KIISC
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• v.26 no.6
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• pp.42-50
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• 2016

Critical infrastructure (CI) such as the electrical grid, transportation systems and water resource systems are controlled by Industrial Control and SCADA (Supervisory Control and Data Acquisition) networks. During the last few years, cyber attackers have increasingly targeted such CI systems. This is of great concern because successful attacks have wide ranging impact and can cause widespread destruction and loss of life. As a result, there is a critical requirement to develop enhanced algorithms and tools to detect cyber threats for SCADA networks. Such tools have key differences with the tools utilized to detect cyber threats in regular IT networks. This paper discusses key factors which differentiate network security for SCADA networks versus regular IT networks. The paper also presents various approaches used for SCADA security and some of the advancements in the area.

• Journal of Information Technology Applications and Management
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• v.11 no.3
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• pp.147-159
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• 2004

Empirical evidence on the maintainability of object-oriented systems is far from conclusive, partly due to lack of representativeness of the subjects and systems used in the study. The present research empirically examined this issue with the systems that are mission-critical. currently operational and maintained by professionals. It was found that the 00 group appeared to consume less time while maintaining more amount of software artifacts than the NOO counterpart. This economical utilization of time appeared evident regardless of software development life cycle. This was due to the usefulness of UML for impact analysis which contributed to effective comprehension and communication. Insufficient design specifications led to ambiguity and costly defects in transferring design solutions to development. Also. the encapsulation of 00 seemed to reduce mental loads at maintenance tasks and improved code reuse. However, the number of files to manage increased and thus. dependency management is required for the 00 systems.

• Journal of Families and Better Life
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• v.19 no.5
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• pp.279-291
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• 2001

This study was peformed to identify a credit limit of the household. For this purpose, the differences in household economy by debt burden and the effects of debt burden on household economy was analyzed with the data of the Family Income and Expenditure Survey in 1999. The results showed that the household with debt burden, are likely to cut savings not consumption expenditures. The critical level of debt burden which distorts the household economy is found to be 25%. If the debt burden of the household exceeds 25%, they are no longer to save and ought to borrow to repay current debt.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.1045-1051
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• 2005

For critical structures and application, where a given reliability must be met, it is necessary to account for uncertainties and variability in material properties, structural parameters affecting the corrosion process, in addition to the statistical and decision uncertainties. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters and the fuzziness of the corrosion time is determined by the fuzzy arithmetic of interval arithmetic and extension principle

• Journal of the Korean Home Economics Association
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• v.42 no.3
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• pp.91-104
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• 2004

This study analyzes the critical factors that decide the job continuity of married women after one of their life events, childbirth. It is based on the employment data from KLIPS(Korea Labor and Income Panel Study). Vols. 1-4, having observed 128 young mothers who gave birth to children after 1997. The analysis showed that women's employment after their maternity leave depend on whether new mother return to their previous job or not. The Following results are obtained: First, women's age, education, availability of caretakers for their children, and family income have a positive effect on the women's return to their pre-leave employers after childbirth. Second, professional or office work and the frequency of job transition before childbirth have a positive effect on women's employment in new jobs after childbirth. Third, women's age, availability of caretakers of their children, and professional or office work are critical factors that have a positive effect on women's job continuity after childbirth, whereas the frequency of job transitions has a negative effect on employment for women.

• Journal of Korean Critical Care Nursing
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• v.13 no.2
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• pp.45-59
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• 2020

Purpose : The purpose of this study was to identify relation of the communication skills, humanistic knowledge and professional quality of life and to investigate the enhancing ways of professional quality of life in intensive-care unit nurses. Methods : The study design was a descriptive survey from 152 intensive-care unit nurses, from December 1 to 30, 2019. The data analysis was with ANOVA, Scheffé test, Pearson's correlation coefficient and Multiple regression using the SPSS/WIN 23.0 program. Results : The factors affecting compassion satisfaction were communication skills (β=0.42, p=.001), satisfaction for working (β=0.61, p=.001), marriage (β=0.23, p=.005), humanistic knowledge (β=0.47, p=.008) and these factors explained 35.6%. The factors affecting secondary traumatic stress were job stress (β=0.19, p=.011), number of patients per nurse (β=-0.36, p=.004) and these factors explained 9.4%. The factors affecting burnout were job stress (β=-0.25, p=.001), communication skills (β=-0.29, p=.001), working period(β=-0.18, p=.010), satisfaction for working (β=-0.31, p=.001), self care (β=-0.11, p=.033) and these factors explained 36%. Conclusion : Therefore, it is necessary to develop solution to improve professional quality of life in intensive-care unit nurses. It needs to develop programs to improve communication skills and humanistic knowledge in order to enhance compassion satisfaction and to improve communication skills to prevent burnout.