• Journal of Korean Tunnelling and Underground Space Association
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• 제11권1호
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• pp.71-83
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• 2009

Shotcrete is an important primary support for tunnelling in rock. The quality control of shotcrete is a core issue in the safe construction and maintenance of tunnels. Although shotcrete may be applied well initially onto excavated rock surfaces, it is affected by blasting, rock deformation and shrinkage and can debond from the excavated surface, causing problems such as corrosion, buckling, fracturing and the creation of internal voids. This study suggests an effective non-destructive evaluation method of the tunnel shotcrete bonding state applied onto hard rocks using the impact-echo (IE) method and ground penetration radar (GPR). To verify previous numerical simulation results, experimental study carried out. Generally, the bonding state of shotcrete can be classified into void, debonded, and fully bonded. In the laboratory, three different bonding conditions were modeled. The signals obtained from the experimental IE tests were analyzed at the time domain, frequency domain, and time-frequency domain (i.e., the Short- Time Fourier transform). For all cases in the analyses, the experimental test results were in good agreement with the previous numerical simulation results, verifying this approach. Both the numerical and experimental results suggest that the bonding state of shotcrete can be evaluated through changes in the resonance frequency and geometric damping ratio in a frequency domain analysis, and through changes in the contour shape and correlation coefficient in a time-frequency analysis: as the bonding state worsens in hard rock condition, the autospectral density increases, the geometric damping ratio decreases, and the contour shape in the time-frequency domain has a long tail parallel to the time axis. The correlation coefficient can be effectively applied for a quantitative evaluation of bonding state of tunnel shotcrete. Finally, the bonding state of shotcrete can be successfully evaluated based on the process suggested in this study.

• 한국노년학
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• 제27권2호
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• pp.487-502
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• 2007

An objective of this study is to verify factor of exercise adherence of the elder who have carried on exercise for many years at non-commercial sports center. To achieve the objective, I used ethnography, a method of qualitative study. The subjects for this study were 5 members of non-commercial sports center. They have been attending lesson which I have been running Taichi for more than 2 years and carried on exercise for more than 5 years. Main results of this study are as follows. First, the elder who have kept on with exercise showed the eagerness to participate and capacity of self-management through their exercise adherence for many years. Second, various factors such as social, environmental, and social psychological on had a strong effect on a continuous exercise performance. The most remarkable thing of results of this study is a close human connection among instructors, manager and companion is the most effectual factor of the elder's exercise adherence.

• Korean Journal of Culture and Social Issue
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• 제14권1호_spc
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• pp.319-348
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• 2008

Self-efficacy, achievement goals, task value, and attribution are some of the representative motivation constructs that explain adolescents' cognition, affect, and behavioral patterns in achievement settings. These constructs have won researchers' recognition by demonstrating explanatory and predictive utility that transcends various social and cultural milieus learners are exposed to. Korean adolescents' motivation is generally in line with this universal trend and can be described adequately with these constructs. Nonetheless, there also exist a host of indigenous factors that shape these motivation constructs to be uniquely Korean. The purpose of the present article was to explore some of the socio-cultural factors that appear to wield particularly determining effects on Korean adolescents' academic motivation. Review of the relevant literature identified interdependent self-construal, traditional morals of filial piety, familism, educational fervor, academic elitism, and the college entrance system as important cultural, social, and policy-related such factors. Also discussed in this article were the roles of these factors in creating more immediate psychological learning environments for Korean adolescents, such as parent-child relationships, teacher-student relationships, and classroom goal structures.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• 제17권6호
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• pp.127-140
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• 2022

The present study assumes that active and voluntary actions of organizational members in domestic enterprises can improve organizational performance as they have to seek differentiated strategies and changes in the midst of infinite competition. Considering the nature of psychological empowerment and proactive behavior, the study conducted a survey on members of companies with 100 or more workers of a certain size and used 300 samples for the study. Accordingly, this study attempted to investigate the relationship between personal factors influencing overall organizational competitiveness, i. e. job engagement, proactive behavior and psychological empowerment. Also, the mediating effects of job engagement on the relationship between psychological empowerment and proactive behavior were also examined here. The analysis established the relationship between psychological empowerment, job engagement and proactive behavior. Also, psychological empowerment was found to exert positive influence on job engagement and proactive behavior to a significant extent. Likewise, job engagement proved to have positive influence on proactive behavior to a significant degree. In addition, the mediating effects of job engagement on the relationship between psychological empowerment and proactive behavior were confirmed. Based on these findings, this study suggested relevant theoretical rationales and practical implications.

• Journal of The Korean Association For Science Education
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• 제44권3호
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• pp.263-271
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• 2024

The demand for inclusive education in school settings has been constantly increasing. Yet, within the context of general subject teacher education, rather than special teacher education, preparation for this remains insufficient. This study aims to investigate and analyze the teacher efficacy for inclusive practices of pre-service science teachers with a focus on identifying differences based on respondent variables. In this research, teacher efficacy for inclusive practices is defined as self-belief in the ability to effectively teach students, including students with disabilities, in inclusive educational environments. It encompasses three sub-dimensions: efficacy in using inclusive instruction, efficacy in collaboration, and efficacy in dealing with disruptive behaviors. Utilizing data from 61 pre-service science teachers using 'Teacher' Efficacy for Inclusive Practices' survey tool, this study examines the distribution of teacher efficacy in inclusive practice across sub-dimensions and differences in distribution based on respondent background. The findings indicate that pre-service science teachers show a generally positive state across all three sub-dimensions, with efficacy to use inclusive instructions and efficacy in collaboration being the highest and efficacy in dealing with disruptive behaviors the lowest. he teachers' efficacy for inclusive practices of pre-service science teachers exhibited some tendencies of difference based on gender, experience with volunteering for individuals with disabilities, experience with inclusive education, and the extent of coursework in special education. However, none of these factors showed statistically significant differences.

• Journal of Navigation and Port Research
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• 제48권3호
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• pp.146-154
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• 2024

The ship management industry in South Korea has been growing steadily, leading the government to implement policies to support its development in response to changing environmental conditions. These policies aim to improve the competitiveness of South Korea's ship management industry by recognizing the importance of skilled professionals in determining its success. Plans and policies have been put in place to cultivate these professionals, but ship management companies are currently facing a serious shortage of manpower. To enhance the industry's competitiveness, it is essential to attract and retain competent ship management professionals. Therefore, this study investigates the reasons for turnover among these professionals. The research results identified four factors contributing to turnover: Work Environment, Economic Compensation and Welfare Benefits, Self-Development, and Promotion and Career Advancement. Subsequent multiple regression analysis based on these factors revealed the need to strengthen economic rewards and benefits in order to reduce turnover rates among ship management professionals. This study provides foundational data for the development of stable human resource management policies for the future of the ship management industry.

• The Journal of the Acoustical Society of Korea
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• 제43권1호
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• pp.29-38
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• 2024

The Matched Field Processing (MFP) is an estimation method for a source range and depth based on the prediction of sound propagation. However, as the frequency increases, the prediction inaccuracy of sound propagation increases, making it difficult to estimate the source position. Recently proposed, the Frequency-Difference Matched Field Processing (FD-MFP) is known to be robust even if there is a mismatch by applying a frequency-difference autoproduct extracted from the auto-correlation of a high frequency signal. In this paper, in order to evaluate the performance of the FD-MFP using a horizontal line array, simulations were conducted in the environment of the East Sea of Korea. In the area of Bottom Bounce (BB) and Convergence Zone (CZ) where detection of a sound source is possible at a long range, and the results of localization were analyzed. According to the the FD-MFP simulations of horizontal line array, the accuracy of localization is similar or degraded compared to the conventional MFP due to diffracted field and mismatch of sound speed. There was no clear result from the simulations conforming that the FD-MFP was more robust to mismatch than the conventional MFP.

• Korean Journal of Environment and Ecology
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• 제33권5호
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• pp.525-538
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• 2019

The purpose of this study was to analyze the habitat status and species diversity of benthic diatoms and estimate the applicability of TDI (Trophic Diatom Index) to obtain the basic data for the identification and management of created wetlands in the Nakdong River. We observed a total of 38 families and 173 species of benthic diatom during the survey period, and spring and autumn showed a similar number of species of 156 and 154, respectively. The result of the SOM (Self-Organizing Map) analysis showed that the distribution of benthic diatom was sensitive to environmental factors such as nutrient concentration and rainfall in each wetland. The cluster 1 was characterized by the survey sites of autumn mostly and consisted of points of high TDI, although the nutrients such as total phosphorus and total nitrogen were low, and the species number and abundance of diatoms were low. Conversely, cluster 4 was characterized by the survey sites of spring mostly and consisted of points of low TDI, even though total nitrogen was high. Considering that most of the created wetlands had the reduced inflow and outflow, the increased flow rate in the summer lowers nutrient values in autumn, and the species number and abundance of benthic diatom decreases due to the increase of turbidity, which reduces the light penetrations to the substrates. On the contrary, the TDI value is low in spring because the low water level causes insufficient substrate surface to the benthic diatoms, and it is too early for the establishment and development of saprophilous species. Although various studies have used TDI as an indicator for evaluating the habitat environment and water quality, it is not a good evaluation indicator in this study since the nutrient concentration in the wetlands mostly high as they have a low flow rate and are close to the stagnant area. Nevertheless, additional periodic surveys that comprehensively reflect the fact that the summer rainfall and inflow/outflow regulating function might affect the species diversity and distribution of benthic diatoms are necessary.

• Journal of the Korean Association of Geographic Information Studies
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• 제18권2호
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• pp.174-189
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• 2015

The objective of this study was to reconstruct spatial information using the results of the investigation and evaluation of the health of the living organisms, habitat, and water quality at the investigation points for the aquatic ecosystem health of the Nakdong River basin, to support the rational decision making of the aquatic ecosystem preservation and restoration policies of the Nakdong River basin using spatial analysis techniques, and to present efficient management methods. To analyze the aquatic ecosystem health of the Nakdong River basin, punctiform data were constructed based on the position information of each point with the aquatic ecosystem health investigation and evaluation results of 250 investigation sections. To apply the spatial analysis technique, the data need to be reconstructed into areal data. For this purpose, spatial influence and trends were analyzed using the Kriging interpolation(ArcGIS 10.1, Geostatistical Analysis), and were reconstructed into areal data. To analyze the spatial distribution characteristics of the Nakdong River basin health based on these analytical results, hotspot(Getis-Ord Gi, $G^*_i$), LISA(Local Indicator of Spatial Association), and standard deviational ellipse analyses were used. The hotspot analysis results showed that the hotspot basins of the biotic indices(TDI, BMI, FAI) were the Andong Dam upstream, Wangpicheon, and the Imha Dam basin, and that the health grades of their biotic indices were good. The coldspot basins were Nakdong River Namhae, the Nakdong River mouth, and the Suyeong River basin. The LISA analysis results showed that the exceptional areas were Gahwacheon, the Hapcheon Dam, and the Yeong River upstream basin. These areas had high bio-health indices, but their surrounding basins were low and required management for aquatic ecosystem health. The hotspot basins of the physicochemical factor(BOD) were the Nakdong River downstream basin, Suyeong River, Hoeya River, and the Nakdong River Namhae basin, whereas the coldspot basins were the upstream basins of the Nakdong River tributaries, including Andong Dam, Imha Dam, and Yeong River. The hotspots of the habitat and riverside environment factor(HRI) were different from the hotspots and coldspots of each factor in the LISA analysis results. In general, the habitat and riverside environment of the Nakdong River mainstream and tributaries, including the Nakdong river upstream, Andong Dam, Imha Dam, and the Hapcheon Dam basin, had good health. The coldspot basins of the habitat and riverside environment also showed low health indices of the biotic indices and physicochemical factors, thus requiring management of the habitat and riverside environment. As a result of the time-series analysis with a standard deviation ellipsoid, the areas with good aquatic ecosystem health of the organisms, habitat, and riverside environment showed a tendency to move northward, and the BOD results showed different directions and concentrations by the year of investigation. These aquatic ecosystem health analysis results can provide not only the health management information for each investigation spot but also information for managing the aquatic ecosystem in the catchment unit for the working research staff as well as for the water environment researchers in the future, based on spatial information.

• 대한공업교육학회지
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• 제42권2호
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• pp.108-122
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• 2017

This research paper is to examine James Watt who led the 1st industrial revolution successfully. His great work was called monumental achievement in the human history of civilization. Here, we looked over the Watts' educational environment during his infant, juvenile, and adolescence period and also, his learning attitude about his own field through literature review. The basic infra of soft and hard wares for the industrial revolution through the process of R & D on new developing steam engine resulted from the very industrial revolution and its R & D environment were to be investigated. The useful information and knowledge from this process of the research are able to give an appropriate educational guidance to bring up the development of creativity in schooling systems. And also a lesson from the past could be used to provide the desirable direction for the 4th industrial revolution which is just begun to start now. The main results from this study are as follows; First, Watts' parents positively guided him onto the technology of manual field because they recognized their son was interested in technology field. The parents' attitude stimulated and guided his sons' self-development, had been equal to the aims of education. Second, Watt made a chance of making friendships with professors of Glasgow University. He spontaneously had done self-directed learning for getting knowledge and technology, and thus he became an expert of practical engineer and theorist. Third, the Lunar society, which was jumping over one's social position in their society of the 18th century through new thinking way, leading new ages had been very good R & D social infra for Watt to open and connect new advanced level of science and technology in his age. This society provided a study environment fields for their members to exchange their ideas of scientific curiosity and freely inquiry, technology informations. They had discussed and understood the issues to be occurred in their own fields and accumulated necessary knowledge for problem-solving, respectively. Such as this R & D system environment will be also considered in the modern research group. Fourth, the entrepreneur such as Boulton, who understand technology and grasp its value in future, is needed. The system of 'grue of management' will support the researcher with financial support, which is necessary in R & D. And the researcher like Watt who takes pleasure in technology itself and study eagerly in his field without financial problems, that is, 'grue of technical expert' is essential when leading to success in the industrial revolution.