• Smart Structures and Systems
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• v.30 no.5
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• pp.521-535
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• 2022

Efficient management of deteriorating civil infrastructure is one of the most important research topics in many developed countries. In particular, the remote displacement measurement of bridges using linear variable differential transformers, global positioning systems, laser Doppler vibrometers, and computer vision technologies has been attempted extensively. This paper proposes a remote displacement measurement system using closed-circuit televisions (CCTVs) and a computer-vision-based method for in-situ bridge bearings having relatively large displacement due to temperature change in long term. The hardware of the system is composed of a reference target for displacement measurement, a CCTV to capture target images, a gateway to transmit images via a mobile network, and a central server to store and process transmitted images. The usage of CCTV capable of night vision capture and wireless data communication enable long-term 24-hour monitoring on wide range of bridge area. The computer vision algorithm to estimate displacement from the images involves image preprocessing for enhancing the circular features of the target, circular Hough transformation for detecting circles on the target in the whole field-of-view (FOV), and homography transformation for converting the movement of the target in the images into an actual expansion displacement. The simple target design and robust circle detection algorithm help to measure displacement using target images where the targets are far apart from each other. The proposed system is installed at the Tancheon Overpass located in Seoul, and field experiments are performed to evaluate the accuracy of circle detection and displacement measurements. The circle detection accuracy is evaluated using 28,542 images captured from 71 CCTVs installed at the testbed, and only 48 images (0.168%) fail to detect the circles on the target because of subpar imaging conditions. The accuracy of displacement measurement is evaluated using images captured for 17 days from three CCTVs; the average and root-mean-square errors are 0.10 and 0.131 mm, respectively, compared with a similar displacement measurement. The long-term operation of the system, as evaluated using 8-month data, shows high accuracy and stability of the proposed system.

• Journal of Practical Engineering Education
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• v.15 no.3
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• pp.751-759
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• 2023

In the era of global aging and the retirement of baby boomers, the response is very intensive and dynamic. As baby boomers actually retire, the terms for middle-aged people have been diversified into middle-aged, midle-elderly, and the new middle, which are also evident in the training process. In line with the timing, the government and academia are also making efforts to advance the development of training courses for middle-aged, along with organizing terms for middle-aged. From this point of view, this study aims to analyze the performance of the three-year training courses (2018-2020) for the new middle at Korea Polytechnics and suggest the direction of development of the new middle training course. As a result of the study, the three-year performance of the Shin middle-aged training course gradually increased, but the completion rate and employment rate gradually decreased, indicating that countermeasures were needed. In addition, campus performance in the metropolitan area was higher than that in the non-capital area, so a plan for this deviation was needed. In addition, the need for the integrated operation of the existing 'middle-aged' and 'the new middle' courses operated by Korea Polytechnics was suggested, and measures to specialize in the new middle-aged were proposed.

• Membrane Journal
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• v.33 no.6
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• pp.325-343
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• 2023

Direct methanol fuel cells (DMFCs) have been attracting attention as energy conversion devices that can directly supply methanol liquid fuel without a fuel reforming process. The commercial polymer electrolyte membranes (PEMs) currently applied to DMFC are perfluorosulfonic acid ionomer-based PEMs, which exhibit high proton conductivity and physicochemical stability during the operation. However, problems such as high methanol permeability and environmental pollutants generated during decomposition require the development of PEMs for DMFCs using novel ionomers. Recently, studies have been reported to develop PEMs using hydrocarbon-based ionomers that exhibit low fuel permeability and high physicochemical stability. This review introduces the following studies on hydrocarbon-based PEMs for DMFC applications: 1) synthesis of grafting copolymers that exhibit distinct hydrophilic/hydrophobic phase-separated structure to improve both proton conductivity and methanol selectivity, 2) introduction of cross-linked structure during PEM fabrication to reduce the methanol permeability and improve dimensional stability, and 3) incorporation of organic/inorganic composites or reinforcing substrates to develop reinforced composite membranes showing improved PEM performances and durability.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.619-628
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• 2023

In this study, we investigated the feasibility of calcium sulfate fertilizer as a stabilizing agent for As and Hg contaminated farmland soil and its stabilization characteristics in 3 different physical forms (particulate, powder, and solution) through a pot experiment including 34 days of lettuce growth. As and Hg contents of the lettuce grown in the stabilized soils were decreased by at least 70%. However the lettuce yield of the soil stabilized with the solution agent was decreased by 46% due to the overabundance of the nutrients from the solution agent. Thus, if a solution-type agent is planned for agricultural farmland soil stabilization, additional tests for optimal dosage are needed to preserve vegetation growth. In Hg fractionation, a lower concentration of elemental fractions and a higher concentration of residual/sulfide fractions were identified in the soils stabilized with the solution, powder, and pariculate agents in descending order while there were no significant changes in As fractionation. Overall results suggest that calcium sulfate fertilizer can be used as a stabilizing agent, and a solution-type agent could be used when the operation of heavy machinery for the soil stabilization process is impossible.

• Journal of the Economic Geographical Society of Korea
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• v.26 no.3
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• pp.337-357
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• 2023

Universities and local governments in Korea are simultaneously experiencing the difficulties of a decrease in the youth population and a decrease in the school-age population, and close cooperation between universities and local governments is urgently needed to solve this problem. Representative methods of such cooperation include the establishment of a regional innovation system and the theories of innovation clusters and triple helix models. In addition to these theories, the aim is to derive sustainable conditions for the local government-university cooperation model by examining various cases of cooperation at home and abroad. This is the purpose of this paper. In particular, through case studies of cooperation between local governments and universities at home and abroad, three types of models (job, education, and housing) were analyzed, and common conditions and requirements for sustainable cooperation were proposed. In order for cooperation between local governments and universities to continue and produce successful results, mutual benefit creation, infrastructure construction and operation appropriate for capabilities, flexibility, and mutual responsibility are necessary. Furthermore, a model that suits the capabilities of local governments and universities must be found, and in this process, the university's research capabilities and commercialization capabilities of research results are especially important. In addition, it is essential to establish a new cooperation system between local governments, universities, and the central government.

• The Journal of Korean Medical History
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• v.35 no.2
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• pp.69-82
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• 2022

Shin Hong-gyun was born on August 20, 1881. The second son of Shin Tae-geom (申泰儉) in Sangsang-ri, Sinbukcheong-myeon, Bukcheong-gun,Hamgyeongnam-do. His family had been practicing East Asian medicine as a family business. At that time, the families of East Asian doctors who passed the general examination of the Joseon Dynasty had been continuing the East Asian medicine business from generation to generation. Starting with exile in North Gando in 1911, he was located in Wangga-dong, 17 Doo-gu, Changbaek-hyeon. In 1915, he met General Choi Un-san in Bongo-dong, treated the soldiers suffering from cellulitis, and participated in the training process to prepare for the upcoming anti-Japanese war. However, because of a growing difference of opinion with General Choi Woon-san, Shin Hong-gyun left Bono-dong after a year and mets Sorae Kim Jung-geon and joined the founding of Wonjonggyo and Daejindan, an anti-Japanese armed group. It is said that Shin Hong-gyun established many schools in Korean villages destroyed by the Gyeongshin disaster and 14 schools were established under the names of Wonjonggyo and Daejin. After the Japanese established the puppet Manchukuo in 1931, the Manchurian Defense Forces were formed. Koreans and Chinese immigrants to Manchuria worked together to carry out a joint Korean-Chinese anti-Japanese operation towards the Japanese Empire. In 1933, 50 of the Daejindan members joined the Korean Independence Army, and among them, Shin Hong-gyun began to work as a medical doctor in earnest. During an ambush in Daejeonryeong Valley, he could not get a proper meal and, to make matters worse, got wet in the rainy season, so the situation was a challenge in various ways. At this time, Shin Hong-gyun showed his knowledge of herbal medicine, picked black wood ear mushrooms that grew wild in the mountains, washed them in rain water, and provided food to the independence fighters and relieved them of hunger. After the Battle of Daejeon-ryeong, the Japanese army's suppression of the independence forces intensified, and most of the independence fighters escaped from the Chinese army's encirclement and were scattered. Ahn Tae-jin and others led the remaining units and continued the anti-Japanese armed struggle in the forest areas of Yeongan, Aekmok, Mokneung, and Milsan.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.185-190
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• 2023

Recently, tracking radar requires the development of millimeter wave tracking radar to acquire target information with high resolution in various environments. The development of millimeter wave tracking radar requires the development of transmission and receiving components that can be applied to the millimeter wave tracking radar, as well as verification of the applicability of the tracking radar. In order to verify the applicability of the developed transmitting and receiving components, it is necessary to develop a signal acquisition device that can control the transmitting and receiving components using the operating concept of a tracking radar and check the status of the received signal. In this paper, we implemented a signal acquisition device that can confirm the applicability of components developed for millimeter wave tracking radar. The signal acquisition device was designed to process in real time the OOOMHz center frequency and OOMHz bandwidth signals input from 4 channels to verify the received signal. In addition, component control applying the tracking radar operation concept was designed to be controlled by communication such as RS422, RS232, and SPI and generation of control signals for the transmission and receiving time. Lastly, the implemented signal acquisition device was verified through a signal acquisition device performance test.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.21-27
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• 2023

As a means of helping ships navigate safely, navigational aids in operation in the maritime envirionment require periodic management, and due to the nature of the environment, it is difficult to visually check the exact state. As a result, the smart navigation aid system, which improves route safety and operational efficiency, utillizes expertise including sensors, communications, and information technology, unlike general route markings. The communication environment of the smart navigation aid system, which aims to ensure the safety of the navigators operating the ship and the safety of the ship, uses a wireless communication network in accordance with the marine environment. The ship collects the information necessary for the maritime environment on the land and operates. In this process, there is a need to consider the wireless communication security guideline. Basically, based on IHO S-100 a standard for facilitating data exchange and SECOM, which provides an interface for safe communication. This paper research a security system for safe communication in a maritime environment. The security system for the basic interface based on the document was presented, and there were some vulnerabillties to data exchange due to the wireless communication characteristics of the maritime environment, and the user authetication part was added considering the vulnerability that unauthorized users can access the service.

• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.271-278
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• 2023

In the present study, A356 melt degassing experiments were conducted under various impeller rotation speed and inert gas flow rate conditions to determine changes in the melt temperature, composition and density during a degassing treatment. The melt temperature was found to decrease gradually as the degassing time increased, but a clear correlation between the impeller rotation speed or inert gas flow rate and the melt heat loss could not be confirmed. Regardless of the impeller rotation speed or inert gas flow rate, the Mg and Ti contents in the A356 melt scarcely changed, even after degassing for more than 10 minutes, while Sr contents decreased at the maximum degassing rate of 70 ppm. From a quantitative analysis of the degassing rate under each experimental condition based on the hydrogen concentration in the melt derived from the melt density and the degassing model equation, the inert gas flow rate was found to affect the degassing rate rather than the impeller rotation speed under the degassing operation condition employed in the present study.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.2
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• pp.141-151
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• 2022

This exploratory study was conducted to derive the components of digital entrepreneurship by targeting the experts related to Information and Communication Technology (ICT). Through the review of previous studies and Delphi analysis, the major components of digital entrepreneurship were derived into the 'digital entrepreneurial orientation area' and the 'digital technology competency area'. The components of digital entrepreneurship are innovativeness, proactiveness, risk-taking, desire for achievement, ability to identify digital business opportunities, digital technology utilization capability, digital operation process establishment capability, digital technology development capability, digital technology acceptance, information exchange, and cooperation network establishment, digital-based customer acquisition and management was presented. The importance and execution of success factors were measured through IPA analysis. The first quadrant(keep up the good work) includes proactiveness, ability to identify digital business opportunities, and ability to establish digital business processes. The second quadrant(concentrate here) includes innovativeness, digital technology development capability, and digital technology acceptance. The third quadrant(low priority) includes risk-taking, desire for achievement, digital technology utilization capacity, and digital-based customer acquisition and management. The fourth quadrant(possible overkill) includes information exchange and cooperation network establishment. This study is meaningful in that it presents the concept and components of digital entrepreneurship for digital entrepreneurs that can be applied in Korea.