• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.3
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• pp.133-149
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• 2021

This study aims to report the behavioral mechanism of steel pipe reinforcement grouting, which is being actively used to ensure the stability of the excavation surface during tunnel excavation, based on measurements taken at the actual site. After using a 12 m steel pipe attached with a shape displacement meter and a strain gauge to reinforce the actual tunnel surface, behavioral characteristics were identified by analyzing the measured deformation and stress of the steel pipe. Taking into account that the steel pipes were overlapped every 6 m, the measured data up to 7 m of excavation were used. In addition, the behavioral characteristics of the steel pipe reinforcement according to the difference in strength were also examined by applying steel pipes with different allowable stresses (SGT275 and SGT550). As a result of analyzing the behavior of steel pipes for 7 hours after the first excavation for 1 m and before proceeding with the next excavation, the stress redistribution due to the arching effect caused by the excavation relaxation load was observed. As excavation proceeded by 1 m, the excavated section exhibited the greatest deformation during excavation of 4 to 6 m due to the stress distribution of the three-dimensional relaxation load, and deformation and stress were generated in the steel pipe installed in the ground ahead of the tunnel face. As a result of comparing the behavior of SGT275 steel pipe (yield strength 275 MPa) and SGT550 steel pipe (yield strength 550 MPa), the difference in the amount of deformation was up to 18 times and the stress was up to 12 times; the stronger the steel pipe, the better it was at responding to the relaxation load. In this study, the behavior mechanism of steel pipe reinforcement grouting in response to the arching effect due to the relaxation load was identified based on the measured data during the actual tunnel excavation, and the results were reported.

• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.120-135
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• 2021

Changdeokgung Rear Garden is an important place to show the essence of the garden culture of the Joseon Dynasty. In the garden landscape experience, the restoration of the road completes the system of connecting the main spaces. Therefore, the restoration of the road requires accurate understanding of its creation, extinction, and maintenance. The purpose of this study was to detail the changes in the path that occurred in the Changdeokgung Palace Rear Garden from the late Joseon Dynasty to the modern and contemporary period by analyzing literature and drawing materials. For a time-series analysis, "Donggwoldo" and "Donggwoldohyeong" produced in the Joseon Dynasty, along with "Changdeokgung Plan Drawing" produced in modern and contemporary times, and aerial photographs were used. Drawings and photographs of different coordinate systems were transformed into one coordinate system in the geographic information system ArcGIS to compare changes in the movements of different periods. The results of the study are as follows. First, a total of 37 sections have been used since Japanese colonial era, of which 13 have been maintained, 14 have disappeared, and 10 have been newly established. Among the extinction sections, the road north of Neungheojeong Pavilion is considered to be an urgent place to connect the space to the garden and restore it to enjoy the scenery. In the new section, it seems necessary to establish a new alternative road or shorten the section for the connecting section between Daebodan and Okryucheon. Second, it was revealed that the biggest and most frequent changes to the road system in the garden were Japanese colonial era and renovations in the 1970s. It is worth noting the changes in the road since the 1970s, rather than Japanese colonial era, where it was difficult to manage the gardens independently. The access road to Okryucheon remained in its original shape until the 1990s, but it was renovated to its current shape due to misperception of the original shape. A project is needed to find out the cause of the change in this period and restore the damaged original shape. The biggest achievement of this study is that it revealed the changes in the garden path of Changdeokgung Palace in modern and contemporary times. The biggest achievement of this study is that it revealed the changes in the road of Changdeokgung Palace Rear Gardens in modern and contemporary times. However, there is a limitation that it has not been able to clearly present the location and shape that should be restored because it has not found data on landscaping plans or maintenance. In order to restore the road using the data revealed in this study, it seems necessary to consider realistic problems such as current space utilization, viewing system, disaster prevention and maintenance.

• Journal of Intelligence and Information Systems
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• v.27 no.1
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• pp.47-64
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• 2021

The global spread of COVID-19 around the world has not only affected many parts of our daily life but also has a huge impact on many areas, including the economy and society. As the number of confirmed cases and deaths increases, medical staff and the public are said to be experiencing psychological problems such as anxiety, depression, and stress. The collective tragedy that accompanies the epidemic raises fear and anxiety, which is known to cause enormous disruptions to the behavior and psychological well-being of many. Long-term negative emotions can reduce people's immunity and destroy their physical balance, so it is essential to understand the psychological state of COVID-19. This study suggests a method of monitoring medial news reflecting current days which requires striving not only for physical but also for psychological quarantine in the prolonged COVID-19 situation. Moreover, it is presented how an easier method of analyzing social media networks applies to those cases. The aim of this study is to assist health policymakers in fast and complex decision-making processes. News plays a major role in setting the policy agenda. Among various major media, news headlines are considered important in the field of communication science as a summary of the core content that the media wants to convey to the audiences who read it. News data used in this study was easily collected using "Bigkinds" that is created by integrating big data technology. With the collected news data, keywords were classified through text mining, and the relationship between words was visualized through semantic network analysis between keywords. Using the KrKwic program, a Korean semantic network analysis tool, text mining was performed and the frequency of words was calculated to easily identify keywords. The frequency of words appearing in keywords of articles related to COVID-19 emotions was checked and visualized in word cloud 'China', 'anxiety', 'situation', 'mind', 'social', and 'health' appeared high in relation to the emotions of COVID-19. In addition, UCINET, a specialized social network analysis program, was used to analyze connection centrality and cluster analysis, and a method of visualizing a graph using Net Draw was performed. As a result of analyzing the connection centrality between each data, it was found that the most central keywords in the keyword-centric network were 'psychology', 'COVID-19', 'blue', and 'anxiety'. The network of frequency of co-occurrence among the keywords appearing in the headlines of the news was visualized as a graph. The thickness of the line on the graph is proportional to the frequency of co-occurrence, and if the frequency of two words appearing at the same time is high, it is indicated by a thick line. It can be seen that the 'COVID-blue' pair is displayed in the boldest, and the 'COVID-emotion' and 'COVID-anxiety' pairs are displayed with a relatively thick line. 'Blue' related to COVID-19 is a word that means depression, and it was confirmed that COVID-19 and depression are keywords that should be of interest now. The research methodology used in this study has the convenience of being able to quickly measure social phenomena and changes while reducing costs. In this study, by analyzing news headlines, we were able to identify people's feelings and perceptions on issues related to COVID-19 depression, and identify the main agendas to be analyzed by deriving important keywords. By presenting and visualizing the subject and important keywords related to the COVID-19 emotion at a time, medical policy managers will be able to be provided a variety of perspectives when identifying and researching the regarding phenomenon. It is expected that it can help to use it as basic data for support, treatment and service development for psychological quarantine issues related to COVID-19.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.6
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• pp.167-187
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• 2020

Currently, Korea is changing into an ultra-aging society, and office workers retire at the age of 49.5 on average from their main jobs, and the national pension is delayed from 62 years old to 65 years old by 2034, so research is needed to prepare for the aging of office workers after retirement. The purpose of this study is to examine the factors affecting the intention to start a business after retirement and the mediating effect of another sense of success expectation on life after retirement, targeting office workers nationwide. Changes in individual attitudes and systematic institutional support are needed to prepare for a sustainable job until the age of 100 after retirement, that is, a start-up utilizing wisdom and experience in work life. As a result of the study, the ability to perform the goal as job performance, economic preparation for retirement preparation, preparation for external relations, and future anxiety have a positive effect on the entrepreneurial will, and the ability to use new technologies as job performance, and physical preparation for retirement. Preparation and preparation for internal relations were found to have no effect. In the influencing relationship between preparation for external relations and the will of start-up, and future anxiety and will of start-up, another sense of success was confirmed to have a partial mediation effect. In the relationship between economic preparation and willingness to start a business, the effect of complete mediation was confirmed. In order to increase the will to start a business after retirement, it was confirmed that another sense of expectation for success was an important variable. Introducing a government-sponsored education system in the company to reduce the government's financial burden due to super-aging and achieve corporate growth through employee training while potential founders, office workers, are employed, and entrepreneurship and goals for the three life goals of office workers By introducing a performance improvement program, we were able to get implications that would be a solution to the growth of individuals and businesses and reducing the government's financial burden.

• Journal of Korean Home Economics Education Association
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• v.32 no.4
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• pp.81-101
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• 2020

The purpose of this study is to develop and implement a process-based evaluation program with the theme of school space design in the housing area of the middle school home economics. In order to achieve For thispurpose, a process-based evaluation program based on the theme of school space design was developed following the ADDIE instructional design model, and the program was executed to a total of 93 students. A questionnaire survey and in-depth interview were conducted for the evaluation of the program. The results of this study are as follows. First, based on the results of a 2015-Revised Curriculum analysis, a school space design program evaluation plan was established, and two evaluation tasks were developed. Accordingly, scoring criteria were prepared and 8 evaluation materials for students and 2 evaluation materials for teachers were developed. A total of 9 sessions were developed for teaching and learning activities and evaluation-linked operation procedures to perform evaluation tasks. As a result of an expert validity test for the program, all items were verified to be appropriate in content validity and content composition with an average of 3.6 to 4 points (4 points). Second, after conducting the school space design program, a survey on students were conducted, and as a result, all three areas of school space design class, process-based evaluation, interest scored high in average scores of 4.12 to 4.27 out of 5. According to the survey and interview results, the program provided new learning opportunities for school space design, the students were able to reach the suggested achievement goals, and the self-assessment, peer evaluation and teacher feedback positively affected the students during the learning process so that they could reflect on their learning and actively participate in the subsequent learning activity. This study has a limitation in generalizability in that the program was conducted on a limited number of students, and future studies are expected to expand the scope in terms of research participants, evaluation criteria, and school space design classes. This study laid the foundation for theory and practice by developing and implementing a process-based evaluation program for home economics education, and it has contribution in that it suggested the possibility that teachers and students can take the initiatives in school space design, focusing on the housing content elements of home economics.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.39 no.4
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• pp.24-37
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• 2021

This study was conducted to newly examine the original landscape of Buyongjeong(芙蓉亭) and Juhamnu(宙合樓) areas in Changdeokgung Palace(昌德宮), focusing on the modern period including the Korean Empire, and to derive useful research results for restoration and maintenance in the future. The study results can be summarized as follows. First, the artificial island in Buyongji(芙蓉池) was originally made up of a straight layer using well-trimmed processed stone. However, during the maintenance work in the 1960s and 1970s, the artificial island in Buyongji was transformed into a mixture of natural and processed stones. The handrail installed on the upper part of the artificial island in Buyongji is a unique facility that is hard to find similar cases. The handrail existed even during the Korean Empire, but was completely destroyed during the Japanese colonial period. Second, Chwibyeong(翠屛), which is currently located on the left and right of Eosumun(魚水門), is the result of a reproduction based on Northern bamboo in 2008. Although there is a view that sees the plant material of Eosumun Chwibyeong as Rigid-branch yew, the specific species is still vague. Looking at the related data and circumstances from various angles, at least in the modern era, it is highly probable that the Eosumun Chwibyeong was made of Chinese juniper like Donggwanwangmyo Shrine(東關王廟) and Guncheongung(乾淸宮) in Gyeongbokgung Palace(景福宮). Third, the backyard of Juhamnu was a space with no dense trees on top of a stone staircase-shaped structure. The stone stairway in the backyard of Juhamnu was maintained in a relatively open form, and it also functioned as a space to pass through the surrounding buildings. However, as large-scale planting work was carried out in the late 1980s, the backyard of Juhamnu was maintained in the same shape as a Terraced Flower Bed, and it was transformed into a closed space where many flowering plants were planted. Fourth, Yeonghwadang Namhaenggak(暎花堂 南行閣), which had a library function like Gyujanggak(奎章閣) and Gaeyuwa(皆有窩), was destroyed in the late 1900s and was difficult to understand in its original form. Based on modern photographs and sketch materials, this study confirmed the arrangement axis of Yeonghwadang Namhaenggak, and confirmed the shape and design features of the building. In addition, an estimated restoration map referring to 「Donggwoldo(東闕圖)」 and 「Donggwoldohyung(東闕圓形)」 was presented for the construction of basic data.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.116-124
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• 2022

In this study, waste air containing ethanol and hydrogen sulfide, was treated by an integrated hybrid system composed of two alternatively-operating UV/photocatalytic reactor-process and biofilter processes of a biofilter system having two units with an improved design (R reactor) and a conventional biofilter (L reactor). Both a pressure drop (△p) per unit process of the integrated hybrid system and a microbe-population-distribution of each biofilter process were observed. The △p of the UV/photocatalytic reactor process turned out very negligible. The △p of the L reactor was observed to increase continuously to 4.0~5.0 mmH₂O (i.e., 5.0~6.25 mmH₂O/m). In case of R reactor, its △p showed the one below ca. 16~20% of the △p of the L reactor. Adopting such microbes-carrying biofilter media with high porosity as waste-tire crumb media, and the improved biofilter design, contributed to △p of this study, reduced by ca. 37~50% and 40~53%, respectively, from the reported △p of conventional biofilter packed with biofilter media of the mixture (50:50) of wood chip and wood bark. In addition, the △p of R reactor in this study, reduced by ca. 80% from the reported △p of conventional biofilter packed with biofilter media of the mixture (75:25) of scoria with high porosity and compost, was mainly attributed to adopting the improved biofilter design. On the other hand, in case of L reactor, the CFU counts in its lowest column was analyzed double as much as those in any other columns. However, in case of R reactor, its CFU counts were bigger by 50% than the one of L reactor and its microbes were evenly distributed at its higher and lower columns of R_dn reactor and R_up reactor. This phenomena was attributed to an even moisture distribution of 50~55% of R reactor at its higher and lower columns. Therefore, R reactor showed superb characteristics in terms of both △p and microbe-population-distribution, compared to L reactor.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.111-132
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• 2022

The comprehensive examination on tendering system has been introduced to the Cultural Heritage repair and restoration field since 2016 to remedy the repair issues of South Gate in 2014. The Cultural Heritage Administration tried to attain the high performance of the cultural heritage repair and restoration works securing the proper payment for the repair and restoration works. It is high time to review the operating performance of the comprehensive examination on tendering system (hereinafter referred to as the "CEOTS"), as the system has been run for over 5 years to correspond with its original goal, i.e., "The Proper Payment in return for the High Performance of Repair and Restoration works." This study intends to analyze 114 tenders of CEOTS from 2016 to 2020. As a result of the analysis of 114 tenders, firstly, more than half of bid winners were in the top 20% of repair & restoration capacity disclosure amount list, which mostly fulfilled the goal of 'attaining high performance.' Secondly, as the winning bid rate is decreasing from 86.847% in 2017 to 85.488% in 2020, the goal of 'guarantee of a proper payment' is not achieved yet. Thirdly, the influence of Economic Evaluation section in CEOTS has been grown since the change of scoring system in CEOTS in 2019. This study identifies two reasons why the winning bid rate of CEOTS has decreased. Firstly, it is caused by the fact that 'the group that got more than 1st place' and 'the first place group' that are more than half of the total bidders have the decreasing bidding rate trend as the years go by. Secondly, the exclusion rate of 'the group that got more than 1st place' is higher than the exclusion rate of 'the group that got less than 1st place', which means the expected winning rate would be lowered. It is proposed that the revision of CEOTS code is needed, i.e. easing the strict rule concerning the exclusion rate as well as setting up the lower bidding limit to prevent the excessive decreasing winning bid rate.

• Korean Journal of Remote Sensing
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• v.38 no.3
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• pp.265-282
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• 2022

Sea surface temperature (SST) is a factor that greatly influences ocean circulation and ecosystems in the Earth system. As global warming causes changes in the SST near the Korean Peninsula, abnormal water temperature phenomena (high water temperature, low water temperature) occurs, causing continuous damage to the marine ecosystem and the fishery industry. Therefore, this study proposes a methodology to predict the SST near the Korean Peninsula and prevent damage by predicting abnormal water temperature phenomena. The study area was set near the Korean Peninsula, and ERA5 data from the European Center for Medium-Range Weather Forecasts (ECMWF) was used to utilize SST data at the same time period. As a research method, Long Short-Term Memory (LSTM) algorithm specialized for time series data prediction among deep learning models was used in consideration of the time series characteristics of SST data. The prediction model predicts the SST near the Korean Peninsula after 1- to 7-days and predicts the high water temperature or low water temperature phenomenon. To evaluate the accuracy of SST prediction, Coefficient of determination (R²), Root Mean Squared Error (RMSE), and Mean Absolute Percentage Error (MAPE) indicators were used. The summer (JAS) 1-day prediction result of the prediction model, R²=0.996, RMSE=0.119℃, MAPE=0.352% and the winter (JFM) 1-day prediction result is R²=0.999, RMSE=0.063℃, MAPE=0.646%. Using the predicted SST, the accuracy of abnormal sea surface temperature prediction was evaluated with an F1 Score (F1 Score=0.98 for high water temperature prediction in summer (2021/08/05), F1 Score=1.0 for low water temperature prediction in winter (2021/02/19)). As the prediction period increased, the prediction model showed a tendency to underestimate the SST, which also reduced the accuracy of the abnormal water temperature prediction. Therefore, it is judged that it is necessary to analyze the cause of underestimation of the predictive model in the future and study to improve the prediction accuracy.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.97-106
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• 2022

Listeria monocytogenes (L. monocytogenes) is one of gram-positive foodborne pathogens with a very high fatality rate. Unlike most foodborne pathogens, L. monocytogenes is capable of growing at low temperatures, such as in refrigerated foods. Thus, various physical and chemical prevention methods are used in the manufacturing, processing and distribution of food. However, there are limitations to the methods such as possible changes to the food quality and the consumer awareness of synthetic preservatives. Thus, the aim of this study was to evaluate the anti-listeria activity of lactic acid bacteria (LAB) isolated from kimchi and characterize the bacteriocin produced by Lactococcuslactis which is one of isolated strains from kimchi. The analysis on the anti-listeria activity of a total of 36 species (Lactobacillus, Weissella, Lactobacillus, and Lactococcus) isolated from kimchi by the agar overlay method revealed that L. lactis NJ 1-10 and NJ 1-16 had the highest anti-listeria activity. For quantitatively analysis on the anti-listeria activity, NJ 1-10 and NJ 1-16 were co-cultured with L. monocytogenes in Brain Heat Infusion (BHI) broth, respectively. As a result, L. monocytogenes was reduced by 3.0 log CFU/mL in 20 h, lowering the number of bacteria to below the detection limit. Both LAB strains showed anti-listeria activity against 24 serotypes of L. monocytogenes, although the sizes of clear zone was slightly different. No clear zone was observed when the supernatants of both LAB cultures were treated with proteinase-K, indicating that their anti-listerial activities might be due to the production of bacteriocins. Heat stability of the partially purified bacteriocins of NJ 1-10 and NJ 1-16 was relatively stable at 60℃ and 80℃. Yet, their anti-listeria activities were completely lost by 60 min of treatment at 100℃ and 15 min of treatment at 121℃. The analysis on the pH stability showed that their anti-listeria activities were the most stable at pH 4.01, and decreased with the increasing pH value, yet, was not completely lost. Partially purified bacteriocins showed relatively stable anti-listeria activities in acetone, ethanol, and methanol, but their activities were reduced after chloroform treatment, yet was not completely lost. Conclusively, this study revealed that the bacteriocins produced by NJ 1-10 and NJ 1-16 effectively reduced L. monocytogenes, and that they were relatively stable against heat, pH, and organic solvents, therefore implying their potential as a natural antibacterial substance for controlling L. monocytogenes in food.