• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.3
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• pp.101-109
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• 2021

Wave observations using a marine X-band radar are conducted by analyzing the backscattered radar signal from sea surfaces. Wave parameters are extracted using Modulation Transfer Function obtained from 3D wave number and frequency spectra which are calculated by 3D FFT of time series of sea surface images (42 images per minute). The accuracy of estimation of the significant wave height is, therefore, critically dependent on the quality of radar images. Wave observations during Typhoon Maysak and Haishen in the summer of 2020 show large errors in the estimation of the significant wave heights. It is because of the deteriorated radar images due to raindrops falling on the sea surface. This paper presents the algorithm developed to increase the accuracy of wave heights estimation from radar images by adopting convolution neural network(CNN) which automatically classify radar images into rain and non-rain cases. Then, an algorithm for deriving the Hs is proposed by creating different ANN models and selectively applying them according to the rain or non-rain cases. The developed algorithm applied to heavy rain cases during typhoons and showed critically improved results.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.21-32
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• 2022

Steel pile foundations are widely used for offshore constructions due to their high bearing capacity and efficiency. Typically, offshore structures that have reached the end of their design life are required to be demolished. However, pile foundations are often left on site due to technical and economic limitations. The pile left on the site not only pollutes the environment, but can also cause obstacles for the construction of new structures. Therefore, research is required to completely eliminate these foundations at the site. In this study, a new type of double-wall pile foundation that can drastically reduce the pull-out load was conceptually proposed, and a series of model tests were performed to validate the performance of the double-wall pile foundation. The installation and extraction of the double-wall pile were simulated in dry sand in the model test, and the measured up-lift load was compared to that of the conventional pile. According to the result, the maximum up-lift load induced by the decommissioning of the double-wall pile was reduced by 45% when compared to the traditional pile in dense sand. This study verified the mechanism for reducing the up-lift load of the double-wall foundation and confirmed the possibility of completely decommissioning a pile that has reached the end of its nominal service life.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.305-326
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• 2022

To realize the recycling utilization of waste concrete and alleviate the shortage of resources, 11 specimens of steel reinforced recycled concrete (SRRC) filled circular steel tube columns were designed and manufactured in this study, and the cyclic loading tests on the specimens of columns were also carried out respectively. The hysteretic curves, skeleton curves and performance indicators of columns were obtained and analysed in detail. Besides, the finite element model of columns was established through OpenSees software, which considered the adverse effect of recycled coarse aggregate (RA) replacement rates and the constraint effect of circular steel tube on internal RAC. The numerical calculation curves of columns are in good agreement with the experimental curves, which shows that the numerical model is relatively reasonable. On this basis, a series of nonlinear parameters analysis on the hysteretic behaviors of columns were also investigated. The results are as follows: When the replacement rates of RA increases from 0 to 100%, the peak loads of columns decreases by 7.78% and the ductility decreases slightly. With the increase of axial compression ratio, the bearing capacity of columns increases first and then decreases, but the ductility of columns decreases rapidly. Increasing the wall thickness of circular steel tube is very profitable to improve the bearing capacity and ductility of columns. When the section steel ratio increases from 5.54% to 9.99%, although the bearing capacity of columns is improved, it has no obvious contribution to improve the ductility of columns. With the decrease of shear span ratio, the bearing capacity of columns increases obviously, but the ductility decreases, and the failure mode of columns develops into brittle shear failure. Therefore, in the engineering design of columns, the situation of small shear span ratio (i.e., short columns) should be avoided as far as possible. Based on this, the calculation model on the skeleton curves of columns was established by the theoretical analysis and fitting method, so as to determine the main characteristic points in the model. The effectiveness of skeleton curve model is verified by comparing with the test skeleton curves.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.500-512
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• 2022

Post-Occupancy Evaluation (POE), which is one of the construction environment evaluation methods, is a series of processes that ask about the functional requirements and satisfaction of an object from a life cycle perspective such as design/construction/residence. However, there are no POE research activities targeting large-scale units. On the other hand, large-scale third-phase new towns are being developed. Therefore, this study conducted a post-residence evaluation (POE) research activity in a large-scale unit (Multifunctional Administrative City). The procedure of this study is to conduct a literature survey on the current status and implications of the multi-functional administrative city area, and based on the research data, derive the Happy City evaluation index for the major issues and special issues of the Happy City. Afterwards, 450 questionnaires were conducted for the residents of Happy City, and POE analysis was performed on the derived data for each module. And based on the analysis results, implications such as problems and improvement points for the current status of the Happy City were derived. This can be used as a basis for the expansion of a large-scale new city into a self-sufficient city, and it can be used as a basic data for the development and improvement of a happy city that meets social needs in the future.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.47-59
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• 2022

A series of experiments were performed to investigate the design and application of a rubble-ground modification method with grout injection. A small-sized injection machine was designed, and the grouts with various mix proportions were injected into 25 mm aggregate using the designed small-sized injection machine. With the compressive strength of the grout ranging from 20 to 80 MPa, the uniaxial compressive strength of the grout-filling bodies with clean gravels was higher than 1/6th of the strength of grouts themselves. However, this fraction may reduce depending on the interface conditions. The erosion resistance of the hardened grout was evaluated, and it was determined that the grout with a strength greater than 15 MPa did not require erosion consideration. Moreover, a full-scale injection test was performed for 25 cm-sized rubbles in cages with a diameter greater than 1 m and a height of 1.2 m to evaluate the filling characteristics of the grout. Results from this test indicated that the grout flowability sensitively influenced the filling characteristics.

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.423-433
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• 2021

The purpose of this study was to establish the concept of self-management in beauty service experts through two integrated research methods of open-ended questionnaires and focus group interview. For data collection, an open-ended questionnaire was conducted for 151 beauty service experts located in Seoul·Gyeonggi-do, and a focus group interview was conducted with 8 experts in beauty experts to collect data. Accordingly, the results derived through a series of research procedures are as follows. First, as a result of the inductive content analysis of the open questionnaire, the self-management of beauty service experts was derived into four types of intellectual management: health management, interpersonal management, appearance management, and technology management. Second, in the results of the focus group interview, the inductive content analysis was more validly supported, and the beauty service field-centered interview cases were dealt with in-depth, resulting in two additional attributes of contactless management and knowledge management. The results of this study can be used as basic data for establishing strategies for life as a successful professional of beauty service workers and developing self-management measurement tools for beauty service experts.

• Journal of Engineering Education Research
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• v.24 no.4
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• pp.3-20
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• 2021

As we have become more interested in 'competency' that means ability to do something around the world, the competency of the best performers has also been introduced in the university curriculum as a concept of core competency. Research continues on why this competency-based education is needed compared to existing academic-oriented education, how it can be introduced into existing curricula, and how it can be developed and evaluated in detail. This study develops and validates core competency assessment tools that can diagnose core competencies of engineering students. Therefore, this research paper conducted a literature review related to core competencies and also core competency assessment tools of university students. It seeks to explore the implications of core competency assessment tools for engineering students and then lay the foundation for competency-based teaching and learning at engineering colleges. And also it defines the concepts of core competencies and each core competency of engineering students through prior research analysis of competence, core competence, and core competence of university students. The primary core competency assessment tool consisted of sub-factors and questions of core competencies. It were modified through the expert validation of the primary one and then it was used as a core competency assessment tools for preliminary investigation. The core competency assessment tools for engineering students are consisted of 6 competencies, 22 sub-factors, and 91 questions. There are core competencies as follows: engineering basic competencies, major engineering competencies, self-management competencies, communication competencies, interpersonal competencies, global competencies. The preliminary survey was conducted on 426 engineering students attending the Engineering Education FESTA 2019. The preliminary findings were derived by conducting exploratory factor analysis, confirmatory factor analysis, question characteristics analysis, and reliability analysis for validation. The core competency assessment tools developed through this study can be used to verify the effectiveness of the curriculum and programs for students at engineering colleges. In addition, the developed core competencies, sub-factors, and questions can be utilized in a series of courses that design, conduct, and evaluate engineering curricula and programs as competency-based curriculum. The significance of this study is to lay the groundwork for providing competency-based education engineering students to develop core competencies.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.33 no.4
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• pp.73-92
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• 2022

This study intends to design a model that can effectively service policy data necessary for the implementation of new national agenda in order to provide high-quality policy information services that go beyond those of the existing Policy Information Portal (POINT) of National Sejong Library. To this end, it was determined that providing an integrated search environment, in lieu of data search through individual access, was necessary. Subsequently, four possible models for a national agenda service model were presented. First, designing a computerized system for both interface and electronic information source aspects was proposed for the national agenda service system operation. Second, designing the Linked Open Data system and the time-series service system for national policy information, providing the translation service of overseas original data, and securing the researcher's desired data were presented for the national agenda service information source operation. Third, strengthening public relations for policy users, building and promoting the site brand, operating SNS channels, and reinforcing the activation of auxiliary materials and the accessibility of external services were proposed for public relations of national agenda service. Fourth, expanding the information network with Open API, cloud service, and overseas libraries was proposed for collaborating and cooperating with the agenda service.

• 지역과문화
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• v.8 no.3
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• pp.27-48
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• 2021

In recent years, China's tourism performing art in a series of new completion of the project, increase the box office of tourism performing arts industry, higher economic income, at the same time led to the formation of brand of tourism performing arts and has a good reputation, with the regional culture, has a certain role in promoting economic development, including Large scenario experience drama is one of the key projects. Large scenario experience drama is a new form of drama that simulates the space design of real environment and enables the audience to have active experience in visual, auditory, smell, taste, touch and other senses with strong interactivity.Large scenario experience drama are adapted from traditional Chinese culture, regional culture and long-passed stories, and combine high technology such as lighting, sound effects, special effects and 3D effects to make the audience's experience more real.As the first Large scenario experience drama in China, 'You Jian Ping-yao' reflects the profound culture of Shanxi with new forms of expression and creative means, in the form of scene experience and make the audience more intuitive feel the 'Shanxi emotion', 'Shanxi sentiment' and 'Shanxi Morality', carry forward the traditional culture at the same time, also passed the Shanxi ancient and great values, strengthened the drama of China's movie village, impetus the development of the tourism industry in Shanxi, drive the Shanxi region of jingjing, gradually formed a complete industrial chain. However, there are also limitations such as improper plot connection and improper tourist management, which can improve the performance effect through more audience interaction and guidance. Therefore, it can be seen that large-scale situational experience dramas play a great role in promoting the dissemination of traditional culture and values, the development of tourism industry, the formation of regional brand characteristics and economic development. Through these, it can be seen that large-scale situational experience plays have enlightenments such as innovative thinking content, gradually forming an industrial chain closed-loop, and broadening publicity channels for the development of live-action performances.

• Korean Journal of Organic Agriculture
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• v.29 no.4
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• pp.613-623
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• 2021

This study was conducted to investigate the effect of addition levels of coffee and green tea by products extract including polyphenols through hot water extraction on rumen fermentation. The treatment groups consisted of coffee extract (CO), green tea extract (GR) and mixed extract (MIX), and the addition level was 10 µL, 20 µL and 30 µL of three levels. The experiment consisted of a total of 10 experimental groups including the control group, and a full factorial design was used. The effect of polyphenol addition in coffee and green tea by-products was analyzed through main and interaction effect of statistical analysis. The total polyphenol content of the extracts was 106.15, 79.10 and 185.25 ㎍ GAE/g DM for coffee by-product, green tea by-product and mixture, respectively. Total gas production was significantly lower in the treatment groups than in the control (114.00 mL/gDM) (p<0.05). Methane emission tended to decrease as the polyphenol addition level increased. Moreover, the MIX showed the lowest methane emission when 30 µL was added (p<0.05). Volatile fatty acids showed a significant difference compared to the treatment group as a control (98.06 mM) (p<0.05), but there was no change according to the level of polyphenols. As a result of the main effect and interaction, it is thought that the effect on methane reduction and improvement of rumen fermentation in MIX20 can be expected. In a series of studies, the addition of 20 µL of a blended extract of coffee and green tea by-products is thought to reduce methane to levels that do not inhibit rumen fermentation.