• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.469-478
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• 2019

Multirotor configurations such as VTOL and urban air mobility have been focused on today due to the high maneuverability. Aerodynamic and aeroacoustic characteristics of multirotor have much difference to those of a single rotor. In this study, a numerical analysis based on the free wake vortex lattice method is used for identifying the wake interaction effect. In order to compare the various configurations and operating conditions, the effects of the spacing between the rotors in hovering flight and the effects of the advancing ratio and the formation in forward flight are discussed. In the hovering flight, the unsteady loading of multirotor changes periodically and loading fluctuation increases as decreasing the spacing. It causes the variation in unsteady loading noise and the noise directivity pattern. In the forward flight, the difference in loading fluctuation and noise characteristics are observed according to the diamond and square formation of rotors. By comparing with results of single rotor analysis, multirotor configurations have different directivity pattern and amplitude of loading noise according to the location of each rotor. As a result, wake interaction effect becomes a highly important factor for aerodynamic and aeroacoustic analysis according to multirotor configurations and operating conditions.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.21-36
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• 2019

To ensure that Korea continues to grow, past governments have been consistent in following a policy of advancing into Russia, Mongolia, and Eurasia. The northern economy can expect to achieve synergistic growth because its economic structure complements that of Korea, which has high energy demand and industrial development. There is also an opportunity to accelerate the growth of the China-Russia-Mongolia economic corridor, which is based on Russia's Look East Policy, China's One Belt One Road, and the Mongolian Steppe Road initiative. The Korean government is pursuing a New Northern Policy to achieve the goal of economic cooperation and peace building with other nations, including North Korea; this policy succeeds the Northern Policy pursued by the previous government. As international economic cooperation requires transportation infrastructure, the demand for shipping, which offers more advantages than road and rail transportation, will increase; thus, it is necessary to prepare for it. Korea's port cities, which have a port that serves as the nodal point for maritime transportation, need to prepare for the New Northern Policy. In this paper, the long-term development of Seosan-Daesan port in the was planned and the North Korea's opening-op plan was considered in accordance with the New Northern Policy. Because international cooperation between the government and the provincial cities is required, cooperation with the Port Authority is needed, along with the proactive attitude of Seosan City, Chungcheongnam-do. The Seosan-Daesan port, which is the center of the liquid energy cargo center, can become the base of the New Northern Policy Region; further, the port can be an opportunity to establish its position as a peaceful economic hub on the west coast of Korea.

• Food Science and Industry
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• v.50 no.2
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• pp.37-51
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• 2017

Food packaging strategies have steadily improved with increasing demand for improved food safety, convenience, and shelf life. The development of edible film has been hailed as a technology substituting packaging using synthetic plastics. There has been a surge for research to develop antimicrobial edible films and coatings that can increase microbiological safety while preserving foods. This review addresses recent results that are useful in advancing and extending research into antimicrobial edible films. In this review, we suggest the trend of the development of antimicrobial edible film/coatings by outlining edible film materials, antimicrobial substances, antimicrobial and physical properties of the films, commercial antimicrobial edible films, and methods to statistically predict the efficacy of antimicrobial edible film/coatings, reported in recent studies.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.320-325
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• 2021

In this study, an optimization for the production of water emulsion was designed by adding an extract of wheat sprout, which is known to contain a large amount of antioxidants. The central composite design of reaction surface analysis method (CCD-RSM) was used for the optimization process. The amount of emulsifier, emulsification time, and added amount of wheat sprout extract were selected as independent variables based on our preliminary experiments. The mean droplet size (MDS), viscosity, and emulsion stability index (ESI) were set as the responses to evaluate the stability of the emulsion. For each independent variable, the P-value and coefficient of determination were evaluated to verify the reliability of the experiments. From the result of CCD-RSM, optimum conditions for the emulsification were determined as 23.6 min, 7.7 wt.%, and 3.9 wt.% for the emulsification time, amount of emulsifier, and amount of sprout, respectively. From the optimized condition obtained, MDS, viscosity, and ESI after 7 days from reaction were estimated as 252.3 nm, 616.7 cP, and 88.7%, respectively. The overall satisfaction was 0.9137, which supported the validity of the experiments, and the error rate was measured at 0.5% or less by advancing the experiments. Therefore, an optimized process for producing an emulsion by adding the malt extract was designed by the CCD-RSM.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.53-59
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• 2021

The marine transport industry generally applies new technologies later than other transport industries, such as airways and railways. Vessels require efficient operation, and their performance and lifespan depend on the level of maintenance and management. Many studies have shown that corrective maintenance (CM) and time-based maintenance (TBM) have restrictions with respect to enabling efficient maintenance of workload and cost to improve operational efficiency. Predictive maintenance (PdM) is an advanced technology that allows monitoring the condition and performance of a target machine to predict its time of failure and helps maintain the key machinery in optimal working conditions at all times. This study presents the development of a marine predictive maintenance (MPdM; maritime predictive maintenance) method based on applying PdM to the marine environment. The MPdM scheme is designed by considering the special environment of the marine transport industry and the extreme marine conditions. Further, results of the study elaborates upon the concept of MPdM and its necessity to advancing marine transportation in the future.

• Maritime Security
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• v.3 no.1
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• pp.45-72
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• 2021

North Korea's cyber capabilities represent a relatively new threat to global financial institutions and foreign governments, particularly the U.S and South Korean governments. Based primarily on publicly available sources, such as journalistic accounts and scholarly publications, this qualitative paper analyzes the ways in which North Korean leader Kim Jong Un has bolstered his country's asymmetric power and advanced his line of byungjin (dual development in the economy and military). Particularly by merging the cyber and maritime domains, North Korean operatives generate more revenue for the regime and helps keep the heavily sanctioned leadership in power. Despite the increased international attention to North Korean hackers, few analysts have examined the important role of cyber in the DPRK's internal political culture, specifically in advancing Kim Jong Un's byungjin line. Cyber fits into the DPRK's longstanding tradition of irregular warfare and guerilla-based armed struggle. Cyber also further advances Kim's personal reputation in the DPRK as an economic innovator and military strategist. This paper pays particular attention to the role of the DPRK's cyber operations in both ideological and maritime contexts. Recently, North Korean hackers have targeted South Korean shipbuilding industries and developed a blockchain scam, known as Marine Chain. North Korean cyber agents have increasingly paid attention to the nexus of cyber and maritime domains in their activities.

• Journal of the Korea Institute of Building Construction
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• v.22 no.3
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• pp.305-316
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• 2022

Domestic construction companies have difficulty in establishing strategies when entering overseas markets because they do not have an overseas construction economic sentiment index to refer to for data on overseas construction prospects. Considering that the fluctuation of overseas construction orders over the past decade has been substantial and large companies and SMEs are actively advancing overseas, this study developed an evaluation model for an overseas construction business sentiment index to grasp the economic experience of overseas construction companies. In 2021 Korean companies earned 30.6 billion in overseas construction contracts, 87% the level of the previous year, despite difficulties such as COVID-19 and low oil prices, thanks to efforts by construction companies to strengthen their strategies for entry, such as regional diversification, and government support for winning orders. Since the overseas construction industry fluctuates greatly due to changes in the international environment, it is necessary to investigate and analyze the economic sentiment index of overseas construction companies. In particular, despite the increase in overseas expansion of small and medium-sized construction companies and engineering companies, the provision of information on the overseas construction market sentiment index is insufficient, limiting the establishment of strategies for overseas construction expansion. Therefore, this study intends to develop an overseas construction market sentiment index model that can understand the economic sentiment of overseas construction companies, provide a forecast for overseas construction, and use it to establish overseas construction strategies and policies.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.211-227
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• 2020

This study intends to analyze the storytelling strategy of EBS's YouTube channel , which has been creating a remarkable cultural phenomenon since April 2019, and to examine the potential for its transition to transmedia franchise. Based on Henry Jenkins'seven principles of transmedia storytelling, shows satisfactory relevance in all but 'multiplicity'out of the 10 capacities consisting of the principles. In particular, was found excellent in terms of core capacities such as 'spreadability', 'immersion', 'worldbuilding', 'continuity', 'drillability' and 'performance'. In addition, critical discourse analysis(CDA) in sociocultural practice dimension of the keywords of the related news articles has discovered that is strongly linked to the following five values: 'social integration', 'resistance against authoritarianism', 'self-dignity and reasonable individualism', 'gender neutrality' and 'ecologism', indicating the reason why the work has been able to resonate so extraordinarily with participants across all generations. By answering the two chosen research questions, this study has proved that has high potential to be successful in evolving into transmedia franchise, while keeping building a new realm of edutainment storytelling by cleverly exploiting EBS's unique identity as a public education broadcaster. is viewed as an exceptional property capable of advancing transmedia storytelling in the local market; thus, productive arguments and contemplation over its evolution in storytelling needs to continue so that it can maintain a long-lasting positive influence.

• Journal of Korean Elementary Science Education
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• v.41 no.2
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• pp.173-185
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• 2022

The purpose of this study is to present a reflective review of the earth and universe units from the revised elementary curriculum of 2007-2015 and suggest changes in the 2022 revised curriculum. For this purpose, we conducted an FGI with earth science educators and elementary school teachers regarding the content elements and system, the achievement standards and inquiry activity composition, and the vertical and horizontal curriculum connectivity. Free response and weighted hierarchical analysis items were incorporated into the FGI to ensure logical consistency of the inductively derived improvement. This analysis revealed that the composition of units by grade group had been unevenly distributed among each of the "earth systems" until the 2015 revised curriculum was finalized. Furthermore, the basic concept was still insufficient. We suggest that achievement standards centered on the learning content and skills must state specific scientific core competencies, and inquiry activities should include rigorous critical thinking, student written responses, and student inquiry and analysis. In the hierarchical analysis items, FGI emphasized the inclusion of essential content elements rather than reduction of content elements, understanding-oriented concept learning rather than interest-centered phenomenon learning, basic concept division learning before integration between subjects, and expanding vertical-horizontal connectivity rather than repeating and advancing learning. There is a limit to the generalizing the suggestions proposed in this study to the common opinion of elementary earth science experts. However, since the main vision of the 2022 revised curriculum is to gather opinions through educational entities' participation in a variety of educational subjects, it is suggested that our results should be incorporated as one of the opinions proposed for the 2022 curriculum revision.

• Journal of Korean Library and Information Science Society
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• v.53 no.3
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• pp.263-285
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• 2022

This study presented the factor analysis on constructing the new factors affecting the middle school students' online learning behaviors from the questionnaires employed among middle school students. A total of 204 students participated and the data were collected in South Korea. The sample of middle school ninth-grade students was selected and used through purposive sampling. Findings from the factor analysis provided evidence for the eight-factor solution for the 35-items accounting for 66.15% of the shared variance. A wide range of factors has been considered to identify students' online learning behaviors. The appropriate experience and use of e-learning in the middle school period is also important as it will be a critical stepstone for future education. This research provides information that has been taken into account for advancing online learning to enhance the quality of e-learning systems for middle school students. The study results provided eight new factors affecting the middle school students' online learning behaviors; that is 1) communication using social media as a learning tool, 2) intention to share information using ICT, 3) addiction of technology, 4) adoption of technology, 5) seeking information using ICT, 6) use of social media learning, 7) information search using ICT, and 8) immersion of technology. This study confirmed that middle school students prefer communication using social media as a learning tool, and value intention to share information using ICT for the most part. The data obtained based on factor analysis can highlight the online learning behaviors towards a mixture of social media learning and ICT to ensure a new educational platform for the future of e-learning. This research expects to be useful for both middle schools of online learning to better understand students' online learning behaviors and design online learning environments and information professionals to better assist students who particularly need digital literacy.