• Korean Journal of Optics and Photonics
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• v.32 no.5
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• pp.209-214
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• 2021

High-power continuous-wave operation of a Yb-doped double-clad fiber laser at 1018 nm, pumped by high-power diode lasers at 976 nm, is reported. Based on numerical calculation of the gain and laser signal power along the length of the Yb fiber, it is found that robust operation at 1018 nm can be achieved for a high Yb³⁺-ion excitation density greater than 11.5%, accompanied by high suppression of the feedback from the fiber's end facet. The Yb fiber laser constructed in house yields 626 W of continuous-wave output at 1018 nm for 729 W of incident pump power, corresponding to a slope efficiency of 86.6%. The prospect for power scaling is considered.

• The Journal of the Korea Contents Association
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• v.20 no.12
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• pp.74-81
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• 2020

As of 2020, due to the influence of fine dust from China and domestic dust, the cloudy sky of Korea has become a daily routine not only in spring but also in autumn/winter. In 2013, the International Cancer Institute under the World Health Organization designated fine dust as a group 1 carcinogen that has been confirmed to be carcinogenic to humans. The purpose of this study is to theoretically review 5 fine dust-related design studies, by analyzing the case of three types of wearable air purifiers on the market, it is to propose an improved open wearable air purifier. As a verification method, a working prototype was produced to measure the amount of fine dust reduction. Therefore, this study derived three design insights of wearable air cleaner through case analysis. First, it maximizes openness by minimizing the area touching the face. Second, the nozzle where the air comes out should be close to the respiratory organ. Third, position of the motor is to be as far away as possible from the ear considering the noise. Based on this, I suggested an open-type wearable air purifier design that maximizes the user openness and improves the wearing comfort. I hope that it will be an opportunity to increase the coverage of wearable air cleaner and protect the respiratory health of users.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.29-43
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• 2021

Coinciding with the advent of COVID-19, online education is on the rise both domestically and globally, and has become an absolutely necessary and irreplaceable form of education. It is a very curious question what the perception of people about the suddenly growing form of education is, and how it has changed. This study investigated changes in consumers' perception of online education using big data. To this end, we divided the time into four stages: before COVID-19 (November to December 2019), after the triggering of COVID-19 (January to February 2020), right after the online classes started (March to April 2020), after experiencing some online education (May to June 2020). Then we conducted text mining, namely, keyword frequency analysis, network analysis, word cloud analysis, and sentiment analysis were performed. The implications derived as a result of the analysis can help education policy makers and educators working in the field to improve online education quality and establish its future directions.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.18-31
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• 2021

Linoleum is a resilient, hygienic, and eco-friendly floor covering. It was developed in England by Frederick Walton in 1863. Made of cork flour, linseed oil, and burlap as its main materials, the flexible and waterproof linoleum became globally popular in the early 20th century. Unlike the vinyl coverings, the burlap-backed linoleum was used not only in commercial spaces but also in household areas like kitchens, bathrooms, and even living rooms. As a global product, linoleum was imported and used in Korean palaces like Deoksugung and Changdeokgung in the early modern period. According to the record Deoksugung Won-Ahn, linoleum was applied to the major buildings, including Hamnyeongjeon, Deokhongjeon, and Jeonggwanheon, and various other venues. The linoleum used in these places are mainly monochrome blue and brown color, which probably means that they are from England. The trade records in the early 20th century show that linoleum was imported mainly from England and America. The Ewangjik building floor plan in the Changdeokgung Palace shows that linoleum was used extensively. There are even some originals, which were laid in 1920 and left in the Changdeokgung Palace. When Daejojeon and Huijeongdang were rebuilt in 1920, the interior was outfitted with western features and linoleum was used in areas such as bathrooms, the tonsorial parlor, and one of the rooms on the west side of Huijeongdang. In situ in the Daejojeon and Huijeongdang areas in the Changdeokgung Palace are monochrome, patterned black, and stylized floral tile patterned, which are closely similar to American products made by ALC and Armstrong company. This study will help us better understand linoleum's characteristics, its uses and the material itself. It will also form the basis for the restoration of Changdeokgung Palace as well as other modern interiors with linoleum flooring in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.59-66
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• 2021

The earthquakes are the natural disasters that can cause the most serious damage to civil structures. Therefore, various studies are being conducted to secure the safety of structures against earthquakes. Most studies on the safety or mechanism of civil structures during earthquakes are being conducted based on lab scale test, because real structure tests are impossible when considering the scale of civil structures. The scaling factor proposed by Iai is mainly cited, but when applying the scaling factor proposed by Iai, there are many difficulties in selecting the structural members necessary for the production of the lab scale model. This is because when applying the scaling factor proposed by Iai, the scaling factor must be applied to the elastic modulus, which is the material property of the structure. Therefore, a new method based on Iai's 's similarity law for determining scale factor is applied in this study where the material property of real structure is same as that of lab-scale model. Through the results of this study, it is considered that the characteristics of the structure calculated through the lab scale model test can more accurately reflect the characteristics of the real structure.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.79-88
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• 2021

COVID-19 is putting the entire performance industry in a dire situation. One of the approaches to overcome this crisis is contactless performance business using video media. But, these contactless performance videos are now found to have their own issues. First, with the increasing demands for these videos, the need for higher-quality video products is also increasing. However, there are many organizations that cannot afford such an investment. Second, it is not possible to have the same unique experience of a live performance with the videos. 360-degree VR performance videos are now gaining attention as an alternative to cope with this issue. As such, the researcher reviewed the production of 360 VR performance videos in general based on the cases of the play and a children's story concert As a result, the researcher could confirm the three benefits of simulated 'live experience through a sense of reality', 'convenience of filming' and 'continuity of acting'. Also, the issues related to this approach including 'Lack of professional filming companies', 'Expensive viewing equipment', 'Absence of Platform' and 'Limitations of Camera Technology', among others have been identified, etc. Based on these findings, the researcher could propose strategies for improvement in order to utilize 360-degree VR performance videos.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.1-14
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• 2020

This study was initiated by the interest in identifying what the characteristics of BTS' preference is in the expanded K-Pop market. For this study, a survey was conducted to Taiwan, Thailand, Vietnam, and Korea where BTS is popular. The results of this study show that Vietnam and Thailand have the most positive perceptions of most of the BTS preferences, and the factors affecting the highest quality were analyzed by the differentiating sense of BTS. BTS' preference is an independent variable consisting of five factors: singers and music, a discriminative sense, global communication, meditative lyrics and Korean sentiment. And it has been shown to have a statistically significant influence on both the fandom star and the fan community at a high level. In particular, the Identification desire for fandom star shows that the discriminative sense and meditative lyrics affect the positive at a high level. Also, the identification desire for the fan community's found that the attraction of singers and music affects the highest level of affection. This study was extended to Southeast Asian and Korean fans through a wide range of survey participants, and it is meaningful that a new perspective on the BTS preference was available. Nonetheless, Failure to take into account the various variables that may affect the fandom effect and the intent to purchase, and the lack of a survey of fans in the U.S. and Europe, which has more fans worldwide, could be a limitation of the study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.607-616
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• 2022

Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.

• Journal of Appropriate Technology
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• v.6 no.2
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• pp.126-135
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• 2020

Recently, with the development of the 4th Industrial Revolution era and the popularization of technologies the maker movement is spreading worldwide in various ways for education, entrepreneurship, and solving social problems. This paper introduces a case of establishing and operating a maker space in Tanzania, East Africa, one of the developing countries. iTEC Tech-shop was established in the first half of 2018 at the Nelson Mandela African Institution of Science and Technology (NM-AIST) in Arusha, Tanzania by Innovative Technology and Energy Center (iTEC), and has been operating for nearly two years. With the allocation of empty warehouse space from NM-AIST, physical facilities were established through the purchase and installation of equipment and hand tools. Based on the advice from Idea Factory of Seoul National University and Fab-Lab Seoul, iTEC Tech-shop operational system were established. Through a total of 7 technical workshops, iTEC Tech-shop provided training courses for about 180 local personnel. In addition, the smart Techshop test-bed project was promoted in order to improve the operation level along with securing sustainability of the Techshop. The case of the iTEC Tech-shop could be a useful case for institutions or organizations promoting the maker movement to developing countries.

• Journal of Popular Narrative
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• v.26 no.1
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• pp.9-39
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• 2020

The aim of this study is to examine how heroic characters with supernatural powers are portrayed, and what shortcomings and desires are present in the societies they are born into, with reference to television series with superheroes such as , , and out of many motifs of Korean television fantasy series. The common feature of the superheroes represented in these three dramas is that they are viewed as monsters symbolizing vigilance and alienation instead of being regarded as typical heroes that are the object of praise and admiration. All three dramas criticize the corruption and limitations of bureaucratic powers such as the judiciary, prosecution, and police. The protagonists showcase their heroics by correcting such problems and helping the weak and the victimized by using their supernatural powers. At the same time, they broach uncomfortable topics, highlight truths that some may wish to hide, and also argue the concept of 'normality' and the 'world of naturalness'. For this reason, they are treated as monsters and alienated. Despite being called upon to solve the problems in reality, the deficiencies and contradictions of our society are also revealed by them. The idea of expressing the repressed desires in reality, is similar to the attributes of fantasy in that it criticizes and overthrows reality in order to meet the desires. This study verified not only the subversive characters of fantasy, but also the limitations when such attributes were combined with the characteristics of the medium of television shows. The significance of this study is to give attention to a genre that had previously been neglected by Korean productions but is now gaining traction, and also to suggest many tasks for researching more subdivided and diversified fantasy dramas in the future.