• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.122-129
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• 2022

In this study, the hydrophilicity of the metal fiber is improved by introducing an oxygen-containing functional group to the fiber surface after treatment of the metal fiber using the oxygen plasma treatment time as an experimental variable. For the surface modification of metal fibers, changes in surface properties before and after plasma treatment were observed using SEM and x-ray photoelectron spectroscopy (XPS). In order to observe the effect of the plasma treatment time on the surface of the metal fiber, the change in contact angle of the metal fiber with respect to a polar solvent and a non-polar solvent was measured. After calculating the change in surface free energy using the measured contact angle, the contact angle and the surface free energy for metal fibers before and after oxygen plasma treatment were compared, and the correlation with the adhesion work was also considered. The microdroplet specimens were prepared to investigate the effect of surface changes of these metal fibers on the improvement of shear strength at the interface when combined with other materials and the interfacial shear strength was measured, and the correlation with the adhesion work was also identified. Therefore, the oxygen plasma treatment of the metal fiber results in an increase in the physical surface area on the fiber surface and a change in contact angle and surface energy according to the introduction of the oxygen-containing functional group on the surface. This surface hydrophilization resulted in improving the interfacial shear strength with the polymer resin.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.353-362
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• 2023

In this research, the usage status and characteristics of user big data of Mobike, a dockless bike sharing service introduced in Suwon city, were analyzed, and multiple regression analysis was performed to identify factors influencing the demand for dockless bike sharing service. For analysis, usage data of bike sharing system in Suwon city in 2019 were obtained, and they were organized by areas. As a result of analyzing the characteristics of the influencing factors selected for each area, it was found that the extension of bicycle roads shows high in areas with high demand for bicycles or adjacent areas. Also, the population of 10-30's shows high in areas with high demand for bicycles or adjacent areas. In addition, it was analyzed that the use of bike sharing system is high in areas with high maintenance rate of bicycle roads and large-scale residential and commercial facilities near residential districts and adjacent areas. As a result of the multiple regression analysis, it is analyzed that length of bicycle·pedestrian roads (non-separated), population of 10-30's, number of railway stations, number of schools, number of commercial facilities, number of industrial facilities factors were significant. It is expected that it may be possible to create an environment in which citizens want to use dockless bike sharing service by identifying factors affecting the number of stationless shared bicycles. Also, the results of data analysis are considered to be contributing to policy data to promote the use of dockless bike sharing.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.2
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• pp.95-111
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• 2023

Korea has achieved a high startup rate by promoting government-led startup policies for national economic and industrial development. However, as high as the startup rate is, the closure rate of startup companies can be judged to be insufficient for the qualitative growth of the domestic startup ecosystem. This study aims to investigate how to improve the survival rate of startups by overcoming the valley of death from a location environment perspective. It analyzes the effects of technology orientation and market orientation of start-ups on management performance and the moderating effects of economic, accessibility, and network factors that constitute the location environment. To achieve the research objectives, the empirical analysis was conducted on start-up companies that received corporate support projects from innovation intermediary organizations. The results show that R&D capability of technology orientation has a significant effect on management performance, and market information generation and market information response of market orientation have a significant effect on management performance. As for the moderating effect, accessibility, a sub-factor of the location environment, has a positive moderating effect on the relationship between technological innovation and managerial performance, and the location environment (economy, accessibility, and network) has a positive moderating effect on the relationship between market information generation and managerial performance. This study compared and analyzed previous studies on the success and failure of start-ups and identified common factors. In addition, this study provides policy implications for the sustainable growth of startups through empirical analysis and interview with stakeholders. For future research, it is necessary to compare and analyze start-ups in metropolitan areas and non-metropolitan areas. In addition, it is necessary to study startups that have moved out of the region and into the metropolitan area to find ways to develop the regional startup ecosystem.

• Journal of agricultural medicine and community health
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• v.22 no.1
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• pp.1-18
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• 1997

This study was carried out to reveal the status of health examination among farmers and to attract more attention to the health care system for farmers. Ten pre-trained medical students interviewed the rural residents 18 years of age and older in eight villages which were randomly selected from a county near Taegu city in Korea, in August 1996. Finally 751 persons were interviewed of whom the percentages of male and female were 41.8%, 58.2% respectively. Among the subjects, 361(48.3%) were fully engaged in farming, 184(24.4%) were partly engaged, and the remaining 206(27.3%) were not engaged in farming at all. The overall prevalence of farmer's disease was 23.0% and there was no significant difference between the group of fully engaged in farming(23.3%) and the group of not-fully engaged(22.9%). But the prevalence of farmer's disease in female subjects(27.8%) was significantly higher than that in male(16.2%)(p<0.01). Among the 288 farmer engaged in spraying pesticide, 113(39.2%) had experienced one or more pesticide related symptoms during last one year, but only 18(15.9%) of them had visited medical facilities due to their symptoms. The experience of receiving education about pesticide was significantly correlated with the degree of wearing protectors during pesticide spraying(p<0.001). Among the 736 persons excluding non-respondents, 281(38.2%) received health examination during last one year ; 176(62.6%) of them received free health examination, and 105(37.4%) received charged one. Among the 533 persons 40 years age and older, only 124(23.3%) had received the 'health examination for the elderly' during last one year, which is provided for the 40 years age and older by Korea medical insurance corporation and medical insurance societies. Most of all beneficiaries of self-employed medical insurance thought the imposed contributions as very expensive(77.4%) or moderately expensive(13.2%). The great majority of farmers are exposed to various health risk factors including pesticide, high temperature, overwork etc. comparable to industrial workers. But farmers are excluded from the regular yearly worker's health examination because of not belonging to a company despite they pay relatively more medical insurance contributions compared with the industrial workers and the urban self-employed medical insureds. It is necessary to develop special health management program for farmers such as the special health examination for the industrial workers exposed harmful agents.

• Membrane Journal
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• v.22 no.2
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• pp.95-103
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• 2012

To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.573-583
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• 2005

[ $PM_{10}\;and\;PM_{2.5}$ ] aerosols were collected at Busan from March, 2004 to December, 2004, and the concentrations of some metal elements were chemically analyzed to study their characteristics. The mean concentration of $PM_{10}$ was $58.2{\mu}g/m^3$ with a range of 8.3 to $161.1{\mu}g/m^3$. The mean concentration of $PM_{2.5}$ was $29.3{\mu}g/m^3$ with a range of 2.8 to $65.3\mu}g/m^3$. The mean mass concentrations of Asian dust and non Asian dust in $PM_{10}$ were $121.5\mu}g/m^3$ and $56.0{\mu}g/,^3$ respectively. The mean values of crustal enrichment factors for six elements (Cd, Cr, Cu, Ni, Pb and Zn) were all higher than 10, possibly suggesting the influence of anthropogenic sources. The crustal enrichment factors of some heavy metal elements in non-Asian dust (NAD) were higher than those in Asian dust (AD), possibly due to anthropogenic emissions transported from industries around this area by westerly wind. The soil contribution ratios for $PM_{10}$ and $PM_{2.5}$ were $15.2\%$ and $17.5\%$ on the whole. and those of AD/NAD for $PM_{10}$ and $PM_{2.5}$ were 1.9 and 2.1, respectively.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.511-517
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• 2015

This research was conducted to evaluate the influence of root restriction materials and media on the growth of runner plantlets of 'Seolhyang' strawberry in a nursery field. To achieve this, the influence of three kinds of root media on the growth of runner plantlets was monitored when polyethylene film was used as the root restriction material. In addition, the influence of various root restriction materials (RRS) such as transparent polyethylene film (PE), non-woven fabric (NF), perforated polyethylene film (PP), and root proofing sheet (RPS) on the changes in volumetric water content (VWC) and temperature of root media as well as growth of runner plantlet were investigated when expanded rice hull (ERH) was used as the root medium. In the comparison of root media, growth parameters such as leaf area and crown thickness at 20 d after fixation as well as crown thickness and fresh weights of root and above-ground tissue at 40 d after runner plantlet fixation were higher in the ERH treatment than in sandy loam and loamy sand. When the influence of RRS was compared, the VWC of ERH was 55% just after irrigation, but decreased to 26% at just before irrigation. Ranges of the VWC as influenced by irrigation cycle were 16 to 10% in the PP and less than 10% in the NF and RPS. The soil temperature in the PE treatment was around $1^{\circ}C$ lower than in NF, PP, and RPS. The differences between day and night temperatures were also smaller in the PE treatment rather than those in NF, PP, and RPS. The growths of runner plantlet 50 d after fixation showed that plant heights as well as fresh weights of root and above-ground tissue were higher in the PE treatment than in NF, PP, and RPS. NF and PP did not effectively restrict roots inside the medium and the roots of runner plantlets penetrated through the root restriction materials resulting in the formation of root system below the restriction materials. The above results indicate that ERH is more effective than sandy loam or loamy sand as root medium. PE rather than NF, PP, or RPS as root restriction material resulted in better growth of runner plantlets in propagation of 'Seolhyang' strawberry. The results of this research will be used for production of high quality runner plantlets in strawberry propagation.

• Journal of Industrial Convergence
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• v.22 no.1
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• pp.149-162
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• 2024

This study is a longitudinal study of female older adults living alone, one of the most vulnerable groups in our society, to determine how their depression changes over time and what factors affect their depression. At the same time, considering that there is a large difference in age among the same older adults, this study divided the female older adults into the young-old and the old-old to see how the predictors of depression in each group differ from each other. The main findings are as follows First, depression among female older adults living alone appears to have a declining pattern over time. In the conditional model, factors affecting the initial level of the depression trajectory among women living alone were found to be associated with lower initial depression values among those living in metropolitan areas rather than non-metropolitan areas, better subjective health, and those who did not exercise. Next, we examined the factors affecting rate of change (slope) in depression among female living alone older adults and found that the higher the age, the larger the metropolitan area, the better the subjective health, the less socializing, and the more socializing, the greater the decrease in depression level. Finally, there were some differences in the pathways affecting the initial value and slope of depression among female older adults living alone between the early and late older adults. Specifically, the higher the initial level of participation in social activities, the greater the change in depression among the late older adults, while there was no significant relationship among the early older adults. In the early older adults, better initial subjective health was associated with a larger change in depression than in the late older adults. Only in the late older adults did those who regularly exercised in the early years have higher initial depression values than those who did not. Based on the results of the above analyses, suggestions were made to reduce depression among female older adults living alone.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.2
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• pp.47-65
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• 2020

With the era of the Fourth Industrial Revolution in sight, innovative business models utilizing new technologies are emerging, and startups are enjoying an abundance of opportunities based on the agility to respond to disruptive innovations and the opening to new technologies. However, what is most important in creating a sustainable start-up ecosystem is not the start-up itself, but the process of research-start-investment-investment-the leap to listing and big business-in order to build a virtuous circle of startups that leads to re-investment. To this end, the environment created in the hub area where start-ups were conducted is important, and these material and non-material environmental factors are described as being inclusive by the word "entrepreneurial ecosystem." This study aims to provide implications for Korea's entrepreneurial ecosystem through the study of the interaction of the elements that make up the start-up ecosystem and the relationship of ecosystem participants in Singapore. Singapore has been consistently mentioned as the top two Asian countries in assessing the start-up environment and business environment. In this process, six elements of the entrepreneurial ecosystem presented by Isenberg(2010)-policies, finance, culture, support, human resources, and market-are the best frameworks for analyzing entrepreneurial ecosystems in terms of well encompassing prior studies related to entrepreneurial ecosystem elements, and a model of regional transformation is formed focusing on some elements to suit Singapore, the target area of study. By considering that Singapore's political nature would inevitably have a huge impact on finance, Smart Nation policy was having an impact on university education related to entrepreneurship, and that the entrepreneurial networks and global connectivity formed within Singapore's start-up infrastructure had a significant impact on Singapore's start-up's performance, researches needed to look more at the factors of policy, culture and market. In addition, qualitative research of participants in the entrepreneurial ecosystem was essential to understand the internal interaction of the elements of the start-up ecosystem, so the semi-structured survey was conducted by visiting the site. As such, this study examined the status of the local entrepreneurial ecosystem based on qualitative research focused on policies, culture and market elements of Singapore's start-up ecosystem, and intended to provide implications for regulations related to start-ups, the role of universities and start-up infrastructure through comparison with Korea. This could contribute not only to the future research of the start-up ecosystem, but also to the creation of a start-up infrastructure, boosting the start-up ecosystem, and the establishment of the orientation of the start-up education in universities.

• Journal of Distribution Science
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• v.10 no.2
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• pp.29-41
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• 2012

This paper undertakes a conceptual review of transaction cost to broaden the understanding of the transaction cost analysis (TCA) approach. More than 40 years have passed since Coase's fundamental insight that transaction, coordination, and contracting costs must be considered explicitly in explaining the extent of vertical integration. Coase (1937) forced economists to identify previously neglected constraints on the trading process to foster efficient intrafirm, rather than interfirm, transactions. The transaction cost approach to economic organization study regards transactions as the basic units of analysis and holds that understanding transaction cost economy is central to organizational study. The approach applies to determining efficient boundaries, as between firms and markets, and to internal transaction organization, including employment relations design. TCA, developed principally by Oliver Williamson (1975,1979,1981a) blends institutional economics, organizational theory, and contract law. Further progress in transaction costs research awaits the identification of critical dimensions in which transaction costs differ and an examination of the economizing properties of alternative institutional modes for organizing transactions. The crucial investment distinction is: To what degree are transaction-specific (non-marketable) expenses incurred? Unspecialized items pose few hazards, since buyers can turn toalternative sources, and suppliers can sell output intended for one order to other buyers. Non-marketability problems arise when specific parties' identities have important cost-bearing consequences. Transactions of this kind are labeled idiosyncratic. The summarized results of the review are as follows. First, firms' distribution decisions often prompt examination of the make-or-buy question: Should a marketing activity be performed within the organization by company employees or contracted to an external agent? Second, manufacturers introducing an industrial product to a foreign market face a difficult decision. Should the product be marketed primarily by captive agents (the company sales force and distribution division) or independent intermediaries (outside sales agents and distribution)? Third, the authors develop a theoretical extension to the basic transaction cost model by combining insights from various theories with the TCA approach. Fourth, other such extensions are likely required for the general model to be applied to different channel situations. It is naive to assume the basic model appliesacross markedly different channel contexts without modifications and extensions. Although this study contributes to scholastic research, it is limited by several factors. First, the theoretical perspective of TCA has attracted considerable recent interest in the area of marketing channels. The analysis aims to match the properties of efficient governance structures with the attributes of the transaction. Second, empirical evidence about TCA's basic propositions is sketchy. Apart from Anderson's (1985) study of the vertical integration of the selling function and John's (1984) study of opportunism by franchised dealers, virtually no marketing studies involving the constructs implicated in the analysis have been reported. We hope, therefore, that further research will clarify distinctions between the different aspects of specific assets. Another important line of future research is the integration of efficiency-oriented TCA with organizational approaches that emphasize specific assets' conceptual definition and industry structure. Finally, research of transaction costs, uncertainty, opportunism, and switching costs is critical to future study.