• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.57-78
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• 2022

The disc cutter and cutterbit, which are the most important factors to increase the excavation efficiency of TBM, are key factors in the design and construction of the cutter head. The arrangement, spacing, number, size, and material of disc cutters suitable for the ground conditions determine the success or failure of TBM construction. The disc cutter, which is a representative consumable part in TBM construction, can cause enormous disruption to the construction cost as well as the construction cost unless accurate prediction of wear and replacement cycle is accompanied. Therefore, in this study, the method of calculating the replacement cycle of the disc cutter calculated at the time of design for the slurry shield TBM field, and the depth of wear and replacement location of the disc cutter that occurred during actual construction were compared by analyzing the field data. For a quantitative comparison, weathered soil/weathered rock, soft rock, and hard rock were classified according to the ground in the section showing constant excavation data, and the trajectory of circle was different depending on the location of the disc cutter, so it was compared and analyzed.

• Journal of Korean Home Economics Education Association
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• v.33 no.4
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• pp.31-48
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• 2021

The purpose of this study was to provide an understanding of the trajectories of multidimensional health among older adults, including depression, chronic diseases, and cognitive function. Data were drawn from the 1-6 waves of the Korean Longitudinal Study of Ageing(KLoSA), and a sample of 2,059 respondents aged 65 and older at baseline was used for the analyses. Latent growth curve models and growth mixture models were used to explore the changes in depression, chronic diseases, cognitive function, and heterogeneous trajectories among them. One-way ANOVAs with Scheffé post-hoc analysis and chi-square tests were used to find differences in sociodemographic characteristics, health behaviors, and life satisfaction across the latent trajectory classes. Latent growth curve models revealed that depressive symptoms and the number of chronic diseases increased over time, while cognitive function showed gradual decreases. Three heterogeneous patterns of multidimensional health trajectories were identified: normal aging, increase in chronic diseases, and chronic deterioration. Significant differences were observed in sociodemographic characteristics, health behaviors, and life satisfaction across the three latent classes. In particular, low educational attainment, household income, and life satisfaction were associated with the chronic deterioration class. Based on the findings, we discussed suggestions for health promotion education targeting older adults. This study also emphasizes the importance of home economics education in promoting health literacy across the life course.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.117-124
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• 2016

Researches on soil microbial community are increasing to assess ecosystem responses to anthropogenic disturbances and to provide an indicator of ecosystem recovery. Microbial communities are able to respond more rapidly to environmental changes than plants and therefore they may provide an early indication of the ecosystem recovery trajectory. This study was conducted using 16S rRNA gene pyrosequencing of soil samples to compare soil bacterial community composition between artificially covered soils of the Baedudaegan ridgeline and their adjacent forest soils in two restoration project sites, Ihwaryeong and Yuksimnyeong, which were completed in 2012 and 2013, respectively. Richness of the Phylum level was 29.3 in Ihwaryeong and 32.3 in Yuksimnyeong. Significant difference in the richness between artificial restored soils and adjacent forest soils(p<0.01) was observed, however no significant difference was observed for site location and soil depth. Acidobacteria(37.3%) and Proteobacteria(31.1%) were more abundant than any other phylum in collected soil samples. Also, we found the significant difference in the relative abundance of the two abundant phyla between artificially restored soils and their adjacent forest soils (Proteobacteria, 38.1% in restored soils vs 24.2% in adjacent forest soils, p<0.01; Acidobacteria, 55.4% in restored soils vs 19.2% in adjacent forest soils, p<0.001). The results support the previous researches indicating that soil bacterial community composition is affected by nutritional status of soils and that Acidobacteria is also strongly influenced by pH, thus favoring soils with lower pH. This study could be utilized to monitor and evaluate restoration success of forest soil environment quantitatively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.73-87
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• 2023

Furnishing traffic safety information can contribute to providing hazard warnings to drivers, thereby avoiding crashes. A smart road lighting platform that instantly recognizes road conditions using various sensors and provides appropriate traffic safety information has therefore been developed. This study analyzes the short-term traffic safety improvement effects of the smart road lighting's tunnel traffic safety information service using surrogate safety measures (SSM). Individual driving behavior was investigated by applying the vehicle trajectory data collected with RADAR in the Anin Avalanche 1 and 2 tunnel sections in Gangneung. Comparing accumulated speeding, speed variation, time-to-collision, and deceleration rate to avoid the crash before and after providing traffic safety information, all SSMs showed significant improvement, indicating that the tunnel traffic safety information service is beneficial in improving traffic safety. Analyzing potential crash risk in the subdivided tunnel and access road sections revealed that providing traffic safety information reduced the probability of traffic accidents in most segments. The results of this study will be valuable for analyzing the short-term quantitative effects of traffic safety information services.

• Korean Journal of Social Welfare Studies
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• v.44 no.2
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• pp.327-358
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• 2013

This study aimed to analyze the trajectories of cognitive function and functional disability, and to identify the impacts of socio-demographic factors on the two variables. Based on the assumption that there are differences according to the progress of cognitive impairment, it focused on examining the differences in trajectories of cognitive function and functional disability between two groups: dementia conversion group and dementia non-conversion group among cognitively normal older adults. This study was conducted based on the data from a 3-wave panel study of a sample of 966 Yeoncheon elderly cohort aged 65 and over between 1997 and 2003. Latent growth curve model and multi-group structural equation modeling were used to examine the hypothesis. Results revealed that dementia conversion group exhibited faster rate of cognitive decline as well as lower initial cognitive level. Difference between two groups was not significant in the initial level of functional disability, yet dementia conversion group showed greater degree of deterioration in the functional disability over time than dementia non-conversion group did. In terms of the influence of socio-demographic factors on cognitive function and functional disability, the cognitive decline was more drastic in the female group, whereas functional decline was more apparent for the male group. The level of education in early life had a strong impact on the cognitive function in later life. Based on these findings, practical implication for high risk groups in cognitive function and functional disability were discussed.

• The Mathematical Education
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• v.63 no.1
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• pp.19-33
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• 2024

This study investigates longitudinal patterns in middle school students' mathematics interest and achievement using panel data from the 4th to 6th year of the Gyeonggi Education Panel Study. Results from the multivariate growth mixture model confirmed the existence of heterogeneous characteristics in the longitudinal trajectory of students' mathematics interest and achievement. Students were classified into four latent classes: a low-level class with weak interest and achievement, a high-level class with strong interest and achievement, a middlelevel-increasing class where interest and achievement rise with grade, and a middle-level-decreasing class where interest and achievement decline with grade. Each class exhibited distinct patterns in the change of interest and achievement. Moreover, an examination of the correlation between intercepts and slopes in the multivariate growth mixture model reveals a positive association between interest and achievement with respect to their initial values and growth rates. We further explore predictive variables influencing latent class assignment. The results indicated that students' educational ambition and time spent on private education positively affect mathematics interest and achievement, and the influence of prior learning varies based on its intensity. The perceived instruction method significantly impacts latent class assignment: teacher-centered instruction increases the likelihood of belonging to higher-level classes, while learner-centered instruction increases the likelihood of belonging to lower-level classes. This study has significant implications as it presents a new method for analyzing the longitudinal patterns of students' characteristics in mathematics education through the application of the multivariate growth mixture model.

• Journal of radiological science and technology
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• v.34 no.1
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• pp.51-58
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• 2011

The aim of the study is to analyze the dose delivery error depending on the depth variation according to target positions and arc trajectories by comparing the simulated treatment planning with the actual dose delivery in conformal arc therapy. We simulated the conformal arc treatment planning with the three target positions (center, 2.5 cm, and 5 cm in the phantom). For the experiments, IMRT body phantom (I’mRT Phantom, Wellhofer Dosimetry, Germany) was used for treatment planning with CT (Computed Tomography, Light speed 16, GE, USA). The simulated treatment plans were established by three different target positions using treatment planning system (Eclipse, ver. 6.5, VMS, Palo Alto, USA). The radiochromic film (Gafchromic EBT2, ISP, Wayne, USA) and dose analysis software (OmniPro-IMRT, ver. 1.4, Wellhofer Dosimetry, Germany) were used for the measurement of the planned arc delivery using 6 MV photon beam from linear accelerator (CL21EX, VMS, Palo Alto, USA). Gamma index (DD: 3%, DTA: 2 mm) histogram and dose profile were evaluated for a quantitative analysis. The dose distributions surrounded by targets were also compared with each plans and measurements by conformity index (CI), and homogeneity index (HI). The area covered by 100% isodose line was compared to the whole target area. The results for the 5 cm-shifted target plan show that 23.8%, 35.6%, and 37% for multiple conformal arc therapy (MCAT), single conformal arc therapy (SCAT), and multiple static beam therapy, respectively. In the 2.5 cm-shifted target plan, it was shown that 61%, 21.5%, and 14.2%, while in case of center-located target, 70.5%, 14.1%, and 36.3% for MCAT, SCAT, and multiple static beam therapy, respectively. The values were resulted by most superior in the MCAT, except the case of the 5 cm-shifted target. In the analysis of gamma index histogram, it was resulted of 37.1, 27.3, 29.2 in the SCAT, while 9.2, 8.4, 10.3 in the MCAT, for the target positions of center, shifted 2.5 cm and 5 cm, respectively. The fail proportions of the SCAT were 2.8 to 4 times as compared to those of the MCAT. In conclusion, dose delivery error could be occurred depending on the target positions and arc trajectories. Hence, if the target were located in the biased position, the accurate dose delivery could be performed through the optimization of depth according to arc trajectory.

• Journal of Technology Innovation
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• v.31 no.3
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• pp.39-73
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• 2023

The field of Management of Technology(MOT) emerged in response to the need for research management within U.S. public research institutions during the 1960s. Since its inception, it has proliferated significantly, being practiced in more than 809 institutions globally and over 19 institutions in Korea, encompassing both research and educational endeavors. Particularly noteworthy is the substantial investment of government resources, primarily channeled through the Ministry of Industry since 2007, which has expeditiously established a comprehensive framework for cultivating graduate-level MOT expertise, marked by both quantitative and qualitative advancements. The educational curriculum in the realm of Korean MOT deviates from foreign counterparts through distinctive pathways, exemplified by its emphasis on industry practice-oriented educational programs, standardization and isomorphism across different schools, as well as its interconnectedness with proximate academic disciplines. This research systematically undertakes an analysis of the curriculum in Korean MOT graduate schools, thereby ascertaining its intrinsic identity and distinct attributes. In this endeavor, a comprehensive examination of eleven principal MOT textbooks(three in Korean and eight in English) is conducted to delineate the primary content of the curriculum across seven thematic domains. Moreover, the study deliberates on its differentiation from neighboring academic disciplines and the definitional attributes of MOT. Subsequently, this analysis also encompasses nine Korean MOT graduate programs, projecting the seven thematic domains onto their respective curricula. The findings illuminate that within the context of Korean graduate programs, a substantial proportion of the curriculum, amounting to 62.5%, is dedicated to facets encompassing the operational aspects of technology management within corporate contexts, technology management specific to varying industries and technologies, and collaborative endeavors between academia and industry in the form of projects and seminars. Evidently, the Korean approach to technology management education is notably geared towards the cultivation of adept practitioners capable of executing technology management functions at a mid-tier managerial level, aligned with the exigencies of regional industries. Grounded in the analysis of technology management curricula, this study extrapolates implications for the future trajectory of MOT education in Korea, encompassing a consideration of the stages of industrial development. It underscores the necessity to augment the educational curricula pertaining conceptual foundation of technology and innovation, strategic perspectives of technology and innovation, and the socio-economic context of technology management.

• Journal of the Korean earth science society
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• v.32 no.3
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• pp.276-293
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• 2011

In this study a modeling system consisting of Weather Research and Forecasting (WRF), Sparse Matrix Operator Kernel Emissions (SMOKE), the Community Multiscale Air Quality (CMAQ) model, and the CMAQ-Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (MADRID) model has been applied to estimate enhancements of $PM_{10}$ during Asian dust events in Korea. In particular, 5 experimental formulas were applied to the WRF-SMOKE-CMAQ (MADRID) model to estimate Asian dust emissions from source locations for major Asian dust events in China and Mongolia: the US Environmental Protection Agency (EPA) model, the Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model, and the Dust Entrainment and Deposition (DEAD) model, as well as formulas by Park and In (2003), and Wang et al. (2000). According to the weather map, backward trajectory and satellite image analyses, Asian dust is generated by a strong downwind associated with the upper trough from a stagnation wave due to development of the upper jet stream, and transport of Asian dust to Korea shows up behind a surface front related to the cut-off low (known as comma type cloud) in satellite images. In the WRF-SMOKE-CMAQ modeling to estimate the PM10 concentration, Wang et al.'s experimental formula was depicted well in the temporal and spatial distribution of Asian dusts, and the GOCART model was low in mean bias errors and root mean square errors. Also, in the vertical profile analysis of Asian dusts using Wang et al's experimental formula, strong Asian dust with a concentration of more than $800\;{\mu}g/m^3$ for the period of March 31 to April 1, 2007 was transported under the boundary layer (about 1 km high), and weak Asian dust with a concentration of less than $400\;{\mu}g/m^3$ for the period of 16-17 March 2009 was transported above the boundary layer (about 1-3 km high). Furthermore, the difference between the CMAQ model and the CMAQ-MADRID model for the period of March 31 to April 1, 2007, in terms of PM10 concentration, was seen to be large in the East Asia area: the CMAQ-MADRID model showed the concentration to be about $25\;{\mu}g/m^3$ higher than the CMAQ model. In addition, the $PM_{10}$ concentration removed by the cloud liquid phase mechanism within the CMAQ-MADRID model was shown in the maximum $15\;{\mu}g/m^3$ in the Eastern Asia area.

• Analytical Science and Technology
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• v.23 no.4
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• pp.371-382
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• 2010

TSP and PM2.5 atmospheric aerosols have been collected at Gosan site of Jeju Island, and their compositions were analyzed to understand the pollution characteristics. The composition ratios of nss (non-sea salt)-$SO_4^{2-}$ and $NH_4^+$ were higher in Gosan site than those in other Korean background and urban sites. However the composition ratio of $NO_3^-$ was conversely lower in Gosan site. From the study of aerosol components according to particle sizes, the anthropogenic nss-$SO_4^{2-}$, $NO_3^-$ and $NH_4^+$ components were mostly existed in the fine particles. But the nss-$Ca^{2+}$, $Na^+$, $Cl^-$ and $Mg^{2+}$ originated from soil and marine sources were distributed relatively in the coarse particles. In the seasonal comparison, the concentrations of nss-$Ca^{2+}$, Al, Fe, Ca and $NO_3^-$ increased in spring season, and nss-$SO_4^{2-}$ showed higher concentration in summer and spring seasons. Based on the factor analysis, the atmospheric aerosols in Gosan site have been found to be influenced largely by anthropogenic sources, and next by marine and soil sources. The backward trajectory analyses showed that the concentrations of nss-$SO_4^{2-}$, $NO_3^-$, Pb and nss-$Ca^{2+}$ increased when the air mass moved from Chinese continent to Jeju area. On the other hand, their concentrations decreased when the air mass moved in from the North Pacific Ocean.