• Journal of ILASS-Korea
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• v.28 no.3
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• pp.143-149
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• 2023

Amidst the drive towards carbon neutrality, interest in renewable synthetic e-fuels is rising rapidly. These fuels, generated through the synthesis of atmospheric carbon and green hydrogen, offer a sustainable solution, showing advantages like high energy density and compatibility with existing infrastructure. The physical properties of e-fuels can be different from those of conventional gasoline based on manufacturing methods, which requires investigations into how the physical properties of e-fuels affect the fuel injection characteristics. This study performs a comparative analysis between conventional and Fischer-Tropsch (F-T) synthetic gasoline (e-gasoline) across various fuel temperatures, including the cold start condition. The fuel properties of F-T synthetic and conventional gasoline are analyzed using a gas chromatography-mass spectrometry technique and the injection rates are measured using a Bosch-tube injection rate meter. The F-T synthetic gasoline exhibited higher density and kinematic viscosity, but lower vapor pressure compared to the conventional gasoline. Both fuels showed an increase in injection rate as the fuel temperature decreased. The F-T synthetic gasoline showed higher injection rates compared to conventional gasoline regardless of the fuel temperature.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.285-303
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• 2023

Interest in building underground spaces is increasing for the creation of downtown infrastructure and efficient space utilization. A representative method of utilizing underground space is a tunnel, and in addition to road tunnels, the construction of utility tunnels such as power conduits and utility conduits is gradually increasing. The current basic tunnel construction method can be divided into NATM (New Austrian Tunnelling Method) and TBM (Tunnel Boring Machine). The NATM is a reliable method, but it is accompanied by vibration and noise due to blasting. In the case of the TBM excavation method, there are disadvantages in terms of construction period and construction cost, but it is possible to improve economic feasibility by introducing appropriate complementary methods. In this study, a blasting method was develop using the NATM after TBM pre-excavation using the protective shield method. This is a method that compensates for the disadvantages of each tunnel construction method, and is expected to reduce construction costs, blasting vibration, and noise. In order to review the performance of the developed method, an experiment was conducted to evaluate the performance of explosion-proof tube to which a protective shield scale model was applied, and the impact of blasting vibration of the protective shield method was analyzed.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.139-148
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• 2020

Through this study, the policy proposals were intended to be presented to the head of the farming policy. Therefore, the meaning of this study is as follows. First, rather than judging the returning farmer on his own, he should provide sufficient information to consult with his family and increase access to agriculture. Second, by opening up SNS and YouTube to returning farmers, they should instill confidence in rural areas by providing them with information about the joy of rural life and the success of farming so that they can easily access information about rural life through villages, youth associations and women's associations. Efforts should be made to create vibrant rural areas by providing infrastructure around farmland, providing various amenities for settling young people and forming a family farmers' association. Third, the head of the return farming policy should come up with customized support policies for the return farming (e.g., one-year farm support, free farm support, institutional sales guarantee, tourism in advanced countries, modernization of farmland facilities). Public relations strategies should also be strengthened so that such policies can lead to agriculture. Finally, the government should provide subsidized economic activities (e.g. Airbnb, donation of expertise and work-related personnel before returning home, rural experience, etc.).

• Journal of Korean Society of Steel Construction
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• v.26 no.3
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• pp.169-176
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• 2014

This paper presents the experimental results of behavior of square CFT columns with large the width-ro thickness ratio strengthened with carbon fiber reinforced polymers (CFRP) sheets subjected to concentrated axial loading. The main parameters were b/t ratio and the number of CFRP layers and 6 specimens were fabricated. The values of b/t were ranged from 60 to 100. From the tests, Maximum increase of 16% was also achieved in axial-load capacity with three transverse layered CFRP applied on four sides of steel tubes. The load capacity decreased up to 41% comparing with nominal load capacity of unstrengthened CFT column. However, for CFRP strengthened CFT, the load capacity decreased up to 32%. Finally, from the load-strain relationships, the local buckling occurred before yield point of steel tubes. Also, from the load-strain relationships, it was observed that local buckling were delayed on CFT columns by CFRP sheets retrofitting.

• The KSFM Journal of Fluid Machinery
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• v.17 no.2
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• pp.24-29
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• 2014

In general, a large-capacity axial flow fan is used for industrial processes or ventilation in a social overhead capital infrastructure. The main characteristics of the large axial-flow fan need a lot of electrical power consumption and operate 24 hours a day, 365 days a year. Since the large axial flow fan consumes several hundreds to thousands kW per hour, both manufacturer and consumer are struggling to select high efficiency products for saving energy and reducing operation cost. Therefore, the performance testing should be accurately conducted in experimental equipments. The performance estimation and uncertainty of measurement of the axial-flow fan gathered from the result from nozzle shaped testing equipments certified with ANSI/AMCA standard and duct shaped testing equipment under the same experimental condition. The experimental results from both facilities have maximum 17% differences in performance evaluation and uncertainty of measurement. As considering that the differences, it is doubt about the reliability of testing result. The test was repeated with the specific term during 12 months because it is important to fully reflect the real conditions and to decide the repeatability of data. The evaluation of duct type testing facilities was failed to get an uncertainty measure. Testing results were previously published. As a series of previous paper, axial fan (∅1690 mm) and duct type testing facilities were fabricated. The purpose of fabricating testing equipment was testing an uncertainty measurement under the controlled environments.

• Journal of the Korean Geotechnical Society
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• v.28 no.11
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• pp.53-67
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• 2012

In this research, stainless steel and heat-shrinkage tube were used for new TDR sensing line to solve the problems of ordinary TDR system. The new TDR line improved the sensitivity of water content and endurance, and reduced the data noise. The saturation degree test and acryl model test were done by revised TDR sensor. From the results, without additional data filtering and quantitative analysis, the raw data were separated into 3 zones; saturated, unsaturated and dried zones easily. In addition, the revised TDR sensor was installed in large-scale embankment model to perform the seepage test. The raw data of the model tests showed the distributed seepage behaviors and separated zones clearly, which were almost the same tendencies as the lab test results.

• Journal of Convergence for Information Technology
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• v.10 no.1
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• pp.22-27
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• 2020

With the deployment of 5G infrastructure, content delivery network (CDN) will be a key role to provide explosive growing services for the independent media and YouTube which contain high-speed mobile contents. Without a local cache, the mobile backhaul and fronthaul should endure huge burden of bandwidth request for users as the increase number of direct accesses from contents providers. To deal with this issue, this paper fist presents both fronthaul solutions for CDN that use dark fibers and a passive optical network (PON). On top of that, we propose the aggregated content request specialized for PON caching and evaluate and compare its performance to legacy schemes through the simulation. The proposed PON caching scheme can reduce average access time of up to 0.5 seconds, 1/n received request packets, and save 60% of backhaul bandwidth compared to the no caching scheme. This work can be a useful reference for service providers and will be extended to further improve the hit ratio of cache in the future.

• Journal of Engineering Education Research
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• v.24 no.1
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• pp.34-45
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• 2021

This research is a case study about "Critical Thinking and Debate Education" class which was done for freshmen at the engineering college of "S" Women's University. Real time remote classes through LMS and ZOOM were the most effective tools under on-line circumstances, considering the fact that video lectures only cannot cultivate students' capabilities of critical thinking and communication. Throughout the analysis on students' self-reflection journals and lecture evaluations, this paper examined considerable future points and the pros and cons of "Critical Thinking and Debate Education" under online presentation and discussion situation. As research outputs, students told they could feel less nervousness and anxiety when they exercise and have a presentation because they could choose familiar space for them. In addition, students also told that they feel comfortable about both self-feedback and peer evaluation, repeatedly seeing the recorded video clip. However, on the contrary, sometimes students felt uncomfortable due to unstable internet connection through the online classes, and they also were regretful about the missing chances of interaction between a teacher and students and of intimate exchanges among students. They also told they had felt a kind of limit of enhancing their presentation skills just in front of the monitor. Considering these outcomes, this research paper points out that online education needs to be proceeded by strengthening multi layered feedback to students with the build-up of a non-face-to-face stable educational infrastructure, application of online instructional strategy, and utilization of YouTube platform and video contents. Through this research paper, I hope the new system of encompassing on/off line "Critical Thinking and Debate Education" and effective teaching and learning method can be developed soon by strengthening the strength of online education.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.317-326
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• 2022

In this study, three health teachers assigned to J-do were analyzed through the FGI research method to find out the difficulties, resolution process, and implications of new health teachers in adapting to teaching during COVID-19. As a result of the study, first, there were difficulties in relationships with parents, especially in the course of numerous calls and daily school status reports in the course of handling infectious diseases. After getting used to the COVID-19 work to some extent, beginning health teachers were burdened with having to think about health room work alone, difficulties in health classes for various students, and the burden of showing expertise as the only medical personnel in emergency situations. Second, new health teachers continued to share and communicate related information through online health teacher groups and YouTube to solve the difficulties of teaching. Third, this teaching adaptation process suggests that specific training to provide practical help to new health teachers is needed at the education office level, and it is necessary to support infrastructure such as class contents related to health classes.