• Journal of the Economic Geographical Society of Korea
• /
• v.16 no.4
• /
• pp.567-584
• /
• 2013

This study aims to explore an evolutionary path of the IT service industry in Fairfax County using the Cluster Adaptive Cycle model in economic geography. The analysis is based on detailed historical and industrial information obtained through a variety of data sources including local archival materials, economic census, and interviews. This study also performs a shift-share analysis during the period of 1990 to 2011. Using the adaptive cycle model, the local IT service industry is indicated by a trajectory of constant cluster mutation. The evolution of the local IT service industry has been closely related to federal government policy due to the regional specificity of the National Capital Region and the proximity of the Department of Defense. Although the economic downturn of the late 2000s, the local IT service industry has been notable resilience and adapted to a changing market and technological environment. This constant mutation of the local industry is resulted from not only high resilience which is based on the large government procurement market, the reinforcement of adaptive capacity of the local firms and the network of economic agents such as firm and supporting institutions, but also high flexibility of the knowledge-based service industry to a changing business environment.

• Child Health Nursing Research
• /
• v.12 no.3
• /
• pp.341-350
• /
• 2006

Purpose: The purpose of this study was to describe high-risk health behaviors in middle school adolescents and to identify factors related to this behavior. Method: This survey study employed a self administered questionnaire given to 621 students enrolled in one middle school located in Gyeonggi province. Using the cluster sampling method, 4 classes from the 7th, 8th, and 9th grades were selected. The survey was done between April 20 and May 19, 2004. Data were analyzed using SAS. Result: The results showed that 19.1% of adolescents smoked cigarettes and 8.4 % drank regularly. The mean score for resilience was 6.92 (range:0-10) and for depression, 23.62 (range:0-50). The adolescents in higher grades reported significantly more experience with pornography. Also, adolescents who reported have fewer conversations with their parents had significantly more experience with pornography. Depression was significantly higher for those students who had better academic skills and higher family income. Resilience level was significantly higher for the students who reported better schools records and higher family income. The most important factor related to the high risk behaviors, depression, and resilience was conversations with parents. Conclusion: This study suggests that to develop an effective high-risk health behavior prevention program for adolescents, it is necessary to include communication skills with the parents.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.8
• /
• pp.145-151
• /
• 2017

Many adolescents in high schools are experiencing school maladjustment by academic stress under the reality of higher-education-oriented schooling. A review of studies of academic stress and school adjustment reveals that ego-optimism is predicted as one of the moderating variables to help adolescents lessen academic stress and increase their school adjustment. The main purpose of this study was to verify the moderating effects of ego-resilience on the relationship between academic stress and school adjustment of adolescents. For this, 496 high school students of tenth and eleventh grade were respectively collected through cluster sampling to be surveyed, and then correlation analysis and moderated regression analysis were conducted. The major findings were as follows. First, there was a negative relationship between academic stress and school adjustment and between academic stress and ego-resilience, but a positive relationship between school adjustment and ego-resilience. Second, the moderating effects of ego-resilience on the relationship between academic stress and school adjustment were not found, although optimism, one of ego-resilience's sub-factors, had a significant moderating effect on them, implying that adolescents' optimism should be enhanced to lessen academic stress and ensure they have a successful school life. The study concludes that optimism is a protective factor for school adjustment caused academic stress and thus schools need to make active efforts to enhance their students' optimism.

• Journal of the Economic Geographical Society of Korea
• /
• v.21 no.4
• /
• pp.303-320
• /
• 2018

This study analyzes the characteristics of the evolution process of the Gumi National Industrial Complex as well as its external and internal drivers based on the cluster adaptation cycle model. The Gumi National Industrial Complex has made remarkable progress through expansion in spatial and industrial realm and has become a representative IT industry cluster in Korea. It evolved during a growth period from the 1990s, a maturity period from the mid-2000s, and a mature stagnation period from the mid-2010s. But it has now entered a period of decline. While external drivers at the international and national level greatly influenced the Gumi National Industrial Complex in its evolution from foundation-building to maturity, internal drivers such as the outflow of large firms as well as a lack of SME research capacity and institutional base have added to the management difficulties of SMEs in the mature stagnation period. Therefore, in order for the Gumi National Industrial Complex to move into a revitalization period that strengthens resilience against external shocks, it is necessary to enhance the capacity of SMEs by expanding the roles of the central government, local government, and support agencies. In addition, it is necessary to create and embed strong medium enterprises within the Gumi National Industrial Complex, so that the Complex can be reborn as a sustainable innovation ecosystem.

• Journal of Life Science
• /
• v.19 no.12
• /
• pp.1758-1763
• /
• 2009

Biological assessments of benthic macroinvertebrates community structure were carried out in ten reservoir inflow and outflow areas of the Nakdong river system from April 2008 to August 2008. The collected benthic macroinvertebrates from the surveyed sites were 9,427.6 inds./$m^2$, 42 species belonging to 29 families and 16 orders. A dominant species was Chironomus sp. and a subdominant species was Ecdyonurus levis. In the all sites, Ephemeroptera had the most number of species (17.81%) and Diptera had the most number of individuals (64.00%). Dominance, species diversity, species richness, and species evenness indexes were 0.68, 2.42, 2.96 and 0.54, respectively. The numbers of benthic macroinvertebrates species in each surveyed site were from 21 (site 9 Jilnal wetland) to 51 (site 2 Yeongcheon reservoir). As a result of an analysis about relative resistance and resilience of stability factors, the most popular group was group I with high indices in both resistance and resilience. Site 7 (Beongae wetland) and site 8 (Jangcheok reservoir) had the highest similarity in the result of cluster analysis using the surveyed benthic macroinvertebrates.

• Safety and Health at Work
• /
• v.4 no.4
• /
• pp.187-196
• /
• 2013

Background: Health, safety, and well-being (HSW) at work represent important values in themselves. It seems, however, that other values can contribute to HSW. This is to some extent reflected in the scientific literature in the attention paid to values like trust or justice. However, an overview of what values are important for HSW was not available. Our central research question was: what organizational values are supportive of health, safety, and well-being at work? Methods: The literature was explored via the snowball approach to identify values and value-laden factors that support HSW. Twenty-nine factors were identified as relevant, including synonyms. In the next step, these were clustered around seven core values. Finally, these core values were structured into three main clusters. Results: The first value cluster is characterized by a positive attitude toward people and their "being"; it comprises the core values of interconnectedness, participation, and trust. The second value cluster is relevant for the organizational and individual "doing", for actions planned or undertaken, and comprises justice and responsibility. The third value cluster is relevant for "becoming" and is characterized by the alignment of personal and organizational development; it comprises the values of growth and resilience. Conclusion: The three clusters of core values identified can be regarded as "basic value assumptions" that underlie both organizational culture and prevention culture. The core values identified form a natural and perhaps necessary aspect of a prevention culture, complementary to the focus on rational and informed behavior when dealing with HSW risks.

• Wind and Structures
• /
• v.39 no.1
• /
• pp.1-14
• /
• 2024

Widespread damages from extreme winds have attracted lots of attentions of the resilience assessment of power distribution systems. With many related environmental parameters as well as numerous power infrastructure components, such as poles and wires, the increased challenge of power asset management before, during and after extreme events have to be addressed to prevent possible cascading failures in the power distribution system. Many extreme winds from weather events, such as hurricanes, generate widespread damages in multiple areas such as the economy, social security, and infrastructure management. The livelihoods of residents in the impaired areas are devastated largely due to the paucity of vital utilities, such as electricity. To address the challenge of power grid asset management, power system clustering is needed to partition a complex power system into several stable clusters to prevent the cascading failure from happening. Traditionally, system clustering uses the Binary Decision Diagram (BDD) to derive the clustering result, which is time-consuming and inefficient. Meanwhile, the previous studies considering the weather hazards did not include any detailed weather-related meteorologic parameters which is not appropriate as the heterogeneity of the parameters could largely affect the system performance. Therefore, a fragility-based network hierarchical spectral clustering method is proposed. In the present paper, the fragility curve and surfaces for a power distribution subsystem are obtained first. The fragility of the subsystem under typical failure mechanisms is calculated as a function of wind speed and pole characteristic dimension (diameter or span length). Secondly, the proposed fragility-based hierarchical spectral clustering method (F-HSC) integrates the physics-based fragility analysis into Hierarchical Spectral Clustering (HSC) technique from graph theory to achieve the clustering result for the power distribution system under extreme weather events. From the results of vulnerability analysis, it could be seen that the system performance after clustering is better than before clustering. With the F-HSC method, the impact of the extreme weather events could be considered with topology to cluster different power distribution systems to prevent the system from experiencing power blackouts.

• 한국노년학
• /
• v.31 no.1
• /
• pp.79-96
• /
• 2011

The purpose of this study was to search the clustering and variables in discriminating the groups by the level of the loss experience and ego-integrity among the elderly. In addition, the study aimed to confirm the moderating effects of variables related to resilience in the relationship between a loss experience and ego-integrity. The subjects were 245 elderly aged 60 or above, most of whom were socially active with comparatively high education levels. Six individual variables(physical self-efficacy, general self-efficacy, social self-efficacy, existential spirituality, religious spirituality, optimism) and five environmental variables(emotional support, instrumental support, informational support, appraisal support, social activity) were used in the study. The results of the study are as follows. To data analysis, ANOVA, Stepwise Discriminant analysis, Cluster analysis, Regression analysis and Two-way analysis of variance was employed. First, the subjects were 4 cluster into overcome group, crisis group, stable group and vulnerable group according to the level of loss experience and ego-integrity. Second, optimism, physical self-efficacy, existential spirituality and emotional support were seen to be significant variables in discriminating the groups. Third, the ego-integrity became higher as the variables related to resilience were increased.

• Journal of the Economic Geographical Society of Korea
• /
• v.24 no.2
• /
• pp.127-142
• /
• 2021

This study identifies the characteristics of changes in the subway passengers and the number of COVID-19 confirmed cases in Seoul. We classify subway stations by applying the principal components extracted based on the correlation between them, and analyzed the passenger traffics and geographical characteristics of each cluster. We extract the "top decile" and "lowest decile" stations among the subway stations that the number of subway passengers have decreased in 2020 compared to 2019, and then examine the population and land use characteristics of station areas both station groups. As the result of cluster analysis according to principal component scores, we obtain 6 cluster types. Subway stations belong to the top deciles which have shown the larger decrease in the passenger traffics tend to more sensitive to COVID-19 shocks. Stations belonging to the top tenth percentile of reduced traffic have a high distribution of daytime traffic, and the hinterland of the station has relatively high land use related to commercial and cultural, religious, and social activities. Therefore, it is expected that the regional resilience around subway stations will also show differences in degree by type.

• The KIPS Transactions:PartC
• /
• v.13C no.2 s.105
• /
• pp.195-202
• /
• 2006

For applying sensor networking technology for our daily life, security service is essential, and pairwise key establishment is the key point for security. In this paper, we propose fairwise key establishment mechanism for secure coumunication in sensor networks. In the mechanism, we cluster the network field before deployment and predistribute key materials to normal sensor nodes and clusterheads. For clusterheads, more key materials are predistributed, and after deployment, sensor nodes which need to establish pairwise keys with other sensor nodes in different clusters make request for related key materials to their own clusterheads. Our proposal reduces the memory requirements for normal sensor nodes by distributing more information to clusterheads, and it raises the security level and resilience against node captures. In addition, it guarantees perfect pairwise key establishments for every pair of neighboring nodes and provides efficient and secure sensor communications.