• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1013-1022
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• 2023

Arbuscular mycorrhizal fungi (AMF) are widespread soil endophytic fungi, forming mutualistic relationships with the vast majority of land plants. Biochar (BC) has been reported to improve soil fertility and promote plant growth. However, limited studies are available concerning the combined effects of AMF and BC on soil community structure and plant growth. In this work, a pot experiment was designed to investigate the effects of AMF and BC on the rhizosphere microbial community of Allium fistulosum L. Using Illumina high-throughput sequencing, we showed that inoculation of AMF and BC had a significant impact on soil microbial community composition, diversity, and versatility. Increases were observed in both plant growth (the plant height by 8.6%, shoot fresh weight by 12.1%) and root morphological traits (average diameter by 20.5%). The phylogenetic tree also showed differences in the fungal community composition in A. fistulosum. In addition, Linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed that 16 biomarkers were detected in the control (CK) and AMF treatment, while only 3 were detected in the AMF + BC treatment. Molecular ecological network analysis showed that the AMF + BC treatment group had a more complex network of fungal communities, as evidenced by higher average connectivity. The functional composition spectrum showed significant differences in the functional distribution of soil microbial communities among different fungal genera. The structural equation model (SEM) confirmed that AMF could improve the microbial multifunctionality by regulating the rhizosphere fungal diversity and soil properties. Our findings provide new information on the effects of AMF and biochar on plants and soil microbial communities.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.483-493
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• 2011

Erosion control dams play a primary role in preventing or controlling natural disasters (landslide and debris flow etc.) and also conserve ecosystem in forested watersheds. This study examines structural characteristics of the dams such as the height of ecosystem control and the ecosystem permeability of the erosion control dams under standard drawings and the existing construction works. The objective of this study was to characterize the type classification of erosion control dams as ecosystem. Average permeability was highest on eco-piller dam (63.0%), followed in increasing order by wire rope (13.9%), silt dam (10.9%), multifunctional dam (7.2%), and gravity dam (0.4%). The height of ecosystem control was highest on gravity dam (3.2 m), followed in increasing order by multifunctional dam (1.7 m), wire rope dam (1.2 m), silt dam (0.6 m), and eco-piller dam (0.0 m). Criteria for defining the height of ecosystem control was indefinite. We grouped erosion control dams into three functional types (eco-connection, eco-semi connection, and eco-disconnection) by considering physical and structural characteristics such as the ecosystem permeability and the height of ecosystem control. The type of eco-connection (permeability > 20%) had connection areas from streambed to adjacent riparian areas, and these connection areas serve as ecosystem corridors for fauna and flora. Typical wildlife species includes mammals, reptiles, amphibians, and fishes. The type of eco-semi connection (5% < permeability < 20%) had < 2 m in the eco-barrier height from streambed, however, this type of dams partially serve as wildlife corridors and often provide fish ways. The type of eco-disconnection (permeability < 5%) had > 2 m in the eco-barrier height from streambed, thereby preventing wildlife movement.

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.676-687
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• 2020

Purpose To analyze the altered brain regions and intrinsic brain activity patterns in trauma-exposed firefighters without posttraumatic stress disorder (PTSD). Materials and Methods Resting-state functional MRI (rsfMRI) was performed for all subjects. Thirty-one firefighters over 40 years of age without PTSD (31 men; mean age, 49.8 ± 4.7 years) were included. Twenty-six non-traumatized healthy controls (HCs) (26 men; mean age, 65.3 ± 7.84 years) were also included. Voxel-based morphometry was performed to investigate focal differences in the brain anatomy. Seed-based functional connectivity analysis was performed to investigate differences in spontaneous brain characteristics. Results The mean z-scores of the Seoul Verbal Learning Test for immediate and delayed recall, Controlled Oral Word Association Test (COWAT) score for animals, and COWAT phonemic fluency were significantly lower in the firefighter group than in the HCs, indicating decreased neurocognitive function. Compared to HCs, firefighters showed reduced gray matter volume in the left superior parietal gyrus and left inferior temporal gyrus. Further, in contrast to HCs, firefighters showed alterations in rsfMRI values in multiple regions, including the fusiform gyrus and cerebellum. Conclusion Structural and resting-state functional abnormalities in the brain may be useful imaging biomarkers for identifying alterations in trauma-exposed firefighters without PTSD.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.25-32
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• 2019

Welded joints and mechanical joints using bolt connection have been used as a pile-to-pile connecting method for PHC piles. These PHC pile joint methods may have difficulty in securing connecting quality and connecting performance in PHC pile joining process. Therefore, this study proposes a non-welded connection plate type mechanical PHC pile joint to improve the disadvantages of existing PHC pile connection methods and to secure the connection performance of PHC pile joint. Its connection performance was evaluated from nonlinear FE analysis and loading tests for actual PHC piles with suggested pile joints. From nonlinear FE analysis for the proposed PHC pile joint, it was evaluated to have sufficient connection performance under flexural, compressive, tensile, shear, and eccentric compressive load condition. PHC piles connected by the suggested connection plate type mechanical PHC pile joint show that they show stable linear behaviors for the crack moment and the flexural moment level of the PHC pile. Therefore, the proposed a non-welded connection plate type mechanical PHC pile joint can secure sufficient connection performance in PHC pile.

• Korean Journal of Cognitive Science
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• v.28 no.4
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• pp.267-297
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• 2017

The anatomical structure of the brain reflects a great amount of information about an individual's cognitive ability. The present study reviewed research on developmental changes in brain structure in relation to biological maturation and intellectual growth focusing on children and adolescents. The purpose of the present study was to achieve an understanding of how children and adolescents' brain matures with development and also to examine whether individual differences in intelligence influences the development of brain structure. The first section introduces methods of measurement and analysis of brain structure, such as voxel-based morphometry and structural covariance. The second section reviews studies on the biological maturation of the brain and variables that influence brain development such as sex, environmental factors, and mental disorders, etc. The third section introduces the Parieto-Frontal Integration Theory of intelligence and reviews studies on the association between intelligence and developmental changes of the brain, including changes in structural covariance and functional connectivity. We conclude with a discussion on educational/clinical implications of this work and directions for future studies.

• Ecology and Resilient Infrastructure
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• v.7 no.3
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• pp.189-198
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• 2020

Wetlands, which provide various ecological services, have been regarded as an important nature-based solution for, for example, sustainable water quality improvement and buffering of impacts from climate change. Although the importance of conserving wetlands to reduce the impacts of various perturbations (e.g., changes of land use, climate, and hydrology) has been acknowledged, the possibility of applying these efforts as a nature-based solution in a macro-scale (e.g., landscape) has been insufficient. In this study, we examine the possibility of ecological network analysis that provides an engineering solution as a nature-based solution. Specifically, we analyzed how land use change affects the structural and functional characteristics (connectivity, network efficiency, and clustering coefficient) of the ecological networks by using the ecological networks generated by multiple dispersal models of the hypothetical inhabiting species in wetlandscape. Changes in ecological network characteristics were analyzed through simultaneously removing wetlands, with two initial conditions for surface area, in the zones where land use change occurs. We set a total number of four zones of land use change with different wetland densities. All analyses showed that mean degree and network efficiency were significantly reduced when wetlands in the zones with high wetland density were removed, and this phenomenon was intensified especially when zones contained hubs (nodes with high degree). On the other hand, we observed the clustering coefficient to increase. We suggest our approach for assessing the impacts of land use change on ecological networks, and with additional analysis on betweenness centrality, we expect it can provide a nature-based engineering solution for creating alternative wetlands.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.728-735
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• 2017

With the proliferation of digital devices, the devices have generated considerable additive white Gaussian noise while acquiring digital images. The most well-known denoising methods focused on eliminating the noise, so detailed components that include image information were removed proportionally while eliminating the image noise. The proposed algorithm provides a method that preserves the details and effectively removes the noise. In this proposed method, the goal is to separate meaningful detail information in image noise environment using the edge strength and edge connectivity. Consequently, even as the noise level increases, it shows denoising results better than the other benchmark methods because proposed method extracts the connected detail component information. In addition, the proposed method effectively eliminated the noise for various noise levels; compared to the benchmark algorithms, the proposed algorithm shows a highly structural similarity index(SSIM) value and peak signal-to-noise ratio(PSNR) value, respectively. As shown the result of high SSIMs, it was confirmed that the SSIMs of the denoising results includes a human visual system(HVS).

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.33-40
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• 2021

In recent years, many construction projects become large and complicated, and construction accidents also steadily increase, which grows interest in the safety and maintenance during construction. Many of the construction accidents are related to temporary construction and structures, but the safety evaluation and management during construction are unclear and indefinite due to the short operating period and continuous change in the formation of the temporary structure. The system support, which is one of the temporary structures to support the pouring load of concrete, was proposed to easily install and dismantle members with connection parts pre-manufactured. The use of the system support is increasing to improve the safety of the temporary structure during construction. However, the system support, which consists of multiple members, still has uncertainties in connectivity between members and supports of vertical members. Therefore, this study analyzed the structure, load, and accident cases of the system support to define the damage scenarios for member connection, support condition, and lateral displacement. The decrease rate of the critical load was analyzed according to the damage scenarios based on the defined unit structure of the system support. In addition, this study provided vulnerable members for each damage scenario, which could induce instability of the temporary structures during design, construction, and operation of the structure.

• Journal of Korea Port Economic Association
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• v.39 no.4
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• pp.163-190
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• 2023

Recently, a framework crystallizing as Environmental, Social, and Governance(ESG) has been exerting significant influence not only on corporate investment and management philosophies but also on national policies. This ESG framework is becoming an essential requirement for all organizations. It has become an obligation at the corporate and national levels, particularly in the maritime, port, and logistics sectors. Anticipating that the adoption and utilization of the ESG framework will reach higher levels when it becomes a necessity, this study utilized data from international organizations such as the United Nations Conference on Trade and Development(UNCTAD), the World Bank, and the World Economic Forum to analyze the impact of the ESG framework on national economic performance through the maritime, port, and logistics sectors using Partial Least Squares Structural Equation Modeling(PLS-SEM). The analysis revealed that while the ESG framework did not have a direct impact on the national economy, it manifested substantial indirect effects through maritime, port, and logistics sectors. Therefore, in these sectors, the establishment of the ESG framework should be recognized not only as an expenditure and obligation but also as a crucial investment that positively influences the national economic performance. The study's findings are limited by the absence of data beyond 2019 due to the impact of COVID-19. Therefore, it is anticipated that more accurate current effects can be ascertained when newer data becomes available.

• Asia Marketing Journal
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• v.13 no.4
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• pp.159-189
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• 2012

What attracts consumers to bloggers' reviews? Consumers would be attracted both by the Bloggers' expertise (i.e., knowledge and experience) and by his/her unbiased manner of delivering information. Expertise and trustworthiness are both virtues of information sources, particularly when there is uncertainty in decision-making. Noting this point, we postulate that consumers' motives determine the relative weights they place on expertise and trustworthiness. In addition, our hypotheses assume that tie strength moderates consumers' expectation on bloggers' expertise and trustworthiness: with expectation on expertise enhanced for power-blog user-group (weak-ties), and an expectation on trustworthiness elevated for personal-blog user-group (strong-ties). Finally, we theorize that the effect of credibility on willingness to accept a review is moderated by tie strength; the predictive power of credibility is more prominent for the personal-blog user-groups than for the power-blog user groups. To support these assumptions, we conducted a field survey with blog users, collecting retrospective self-report data. The "gourmet shop" was chosen as a target product category, and obtained data analyzed by structural equations modeling. Findings from these data provide empirical support for our theoretical predictions. First, we found that the purposive motive aimed at satisfying instrumental information needs increases reliance on bloggers' expertise, but interpersonal connectivity value for alleviating loneliness elevates reliance on bloggers' trustworthiness. Second, expertise-based credibility is more prominent for power-blog user-groups than for personal-blog user-groups. While strong ties attract consumers with trustworthiness based on close emotional bonds, weak ties gain consumers' attention with new, non-redundant information (Levin & Cross, 2004). Thus, when the existing knowledge system, used in strong ties, does not work as smoothly for addressing an impending problem, the weak-tie source can be utilized as a handy reference. Thus, we can anticipate that power bloggers secure credibility by virtue of their expertise while personal bloggers trade off on their trustworthiness. Our analysis demonstrates that power bloggers appeal more strongly to consumers than do personal bloggers in the area of expertise-based credibility. Finally, the effect of review credibility on willingness to accept a review is higher for the personal-blog user-group than for the power-blog user-group. Actually, the inference that review credibility is a potent predictor of assessing willingness to accept a review is grounded on the analogy that attitude is an effective indicator of purchase intention. However, if memory about established attitudes is blocked, the predictive power of attitude on purchase intention is considerably diminished. Likewise, the effect of credibility on willingness to accept a review can be affected by certain moderators. Inspired by this analogy, we introduced tie strength as a possible moderator and demonstrated that tie strength moderated the effect of credibility on willingness to accept a review. Previously, Levin and Cross (2004) showed that credibility mediates strong-ties through receipt of knowledge, but this credibility mediation is not observed for weak-ties, where a direct path to it is activated. Thus, the predictive power of credibility on behavioral intention - that is, willingness to accept a review - is expected to be higher for strong-ties.