• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.3
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• pp.101-109
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• 2021

Wave observations using a marine X-band radar are conducted by analyzing the backscattered radar signal from sea surfaces. Wave parameters are extracted using Modulation Transfer Function obtained from 3D wave number and frequency spectra which are calculated by 3D FFT of time series of sea surface images (42 images per minute). The accuracy of estimation of the significant wave height is, therefore, critically dependent on the quality of radar images. Wave observations during Typhoon Maysak and Haishen in the summer of 2020 show large errors in the estimation of the significant wave heights. It is because of the deteriorated radar images due to raindrops falling on the sea surface. This paper presents the algorithm developed to increase the accuracy of wave heights estimation from radar images by adopting convolution neural network(CNN) which automatically classify radar images into rain and non-rain cases. Then, an algorithm for deriving the Hs is proposed by creating different ANN models and selectively applying them according to the rain or non-rain cases. The developed algorithm applied to heavy rain cases during typhoons and showed critically improved results.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.488-498
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• 2021

This study applied Flipped Learning teaching and learning method to Basics Cooking Practice Subject using YouTube. The purpose of this study is to investigate whether the curriculum is properly progressing by grasping the effects of before and after learning and analyzing learners' subjectivity through the learning process. The investigation period was conducted from August 01, 2020 to September 10, 2020. According to the research design of Q Methodology, it was divided into five stages: Q sample selection, P sample selection, Q sorting, coding and recruiting, conclusion and discussion. As a result of the analysis, the first type (N=5): Prior Learning effect, the second type (N=7): Simulation practice effect, and the third type (N=3): self-efficacy effect. As a result, by applying the flipped learning teaching method of the Basics Cooking Practice Subject using YouTube, positive effects such as inducing interest in the class and increasing confidence were found in active learners, but some learners lacked understanding of the system of the class operation method. However, the lack of number of training sessions compared to other subjects is considered to be a solution to be solved later.

• Membrane Journal
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• v.31 no.6
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• pp.371-383
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• 2021

Anion exchange membranes have been used for water electrolysis, which can produce hydrogen, and fuel cells, which can generate electrical energy using hydrogen fuel. Anion exchange membranes operate based on hydroxide ion (OH^-) conduction under alkaline conditions. However, since the anion exchange membrane shows relatively low ion conductivity and alkaline stability, there is still a limit to its commercialization in water electrolysis and fuel cells. To address these issues, it is important to develop novel anion exchange membrane materials by rationally designing a polymer structure. In particular, the polymer structure and synthetic method need to be controlled. By doing so, for polymers, the physical properties, ionic conductivity, and alkaline stability can be maintained. Among many anion exchange membranes, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is commercially available and easily accessible. In addition, the PPO has relatively high mechanical and chemical stability compared to other polymers. In this review, we introduce the recent development strategy and characteristics of PPO-based polymer materials used in anion exchange membranes.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.45-51
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• 2022

Fear of contact exists due to the prevention of the spread of infectious diseases such as COVID-19. When using the common entrance door of an apartment, access is possible only if the resident enters a password or obtains the resident's permission. There is the inconvenience of having to manually enter the number and password for the common entrance door to enter. Also, contactless entry is required due to COVID-19. Due to the development of ICT, users can be easily identified through the development of face recognition and voice recognition technology. The proposed method detects a visitor's face through a CCTV or camera attached to the common entrance door, recognizes the face, and identifies it as a registered resident. Then, based on the registered information of the resident, it is possible to operate without contact by interworking with the elevator on the server. In particular, if face recognition fails with a hat or mask, the visitor is identified by voice or additional authentication of the visitor is performed based on the voice message. It is possible to block the spread of contagiousness without leaving any contactless function and fingerprint information when entering and exiting the front door of an apartment house, and without the inconvenience of access.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.83-91
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• 2022

Seismic design and analysis of nuclear power plant components are performed based on an decoupled model. However, this decoupled analysis has a limitation in that it generates inaccurate results compared to the coupled analysis because it cannot simulate actual phenomena such as the interaction between structures and components. Thus, this study performed seismic coupled and decoupled analysis on an existing nuclear containment structure and related components, considering the mass and natural frequency ratios. And based on these results, comparative analyses of responses of components were conducted. Consequently, the seismic coupled analysis result generally gave a smaller value than the decoupled analysis result. These results were similar to the analysis results for the simple coupled model, which was an existing study, but the difference in component responses was much more pronounced. Also, this was influenced by the installation location of the component rather than the influence of the input frequency of the input seismic motions. Finally, the difference between the decoupled and coupled seismic analysis occurred in the region where the mass ratio of the components was large, and the natural frequencies were almost similar due to the considerable dynamic interaction between the structure and the component in this realm.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.149-158
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• 2021

Advances in food packaging play an important role in keeping food manufacturing and food supply safe. Food packaging facilitates the storage, handling, transportation and preservation of food, and also contributes to the minimization of food waste. On the other hand, food packaging materials have high production volumes, short usage times, and accelerate the occurrence of environmental problems related to waste. The circular economy has already been introduced to pursue sustainability through resource conservation and recycling, and to reduce waste and carbon emissions. By activating an eco-friendly economic system that minimizes resource depletion and environmental pollution, reducing, reusing, recycling and redesigning the goals of the circular economy will reduce the impact of food packaging on the environment. This review focused on the safety aspects of recycled food packaging as recycling is currently considered an important means of packaging waste management. Assessing the safety of recycled packaging is very important because recycling can increase the levels of potentially hazardous chemicals in packaging and in the food after they are migrated. Various food packaging materials such as plastic, paper and cardboard, aluminum, steel, and multi-material multi-layers packaging are commonly used, but only the recycling safety of plastic food packaging materials, which is the most used and has a significant increase in post-use problem, is discussed in this review.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.4
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• pp.581-590
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• 2022

It is important to create a decent pedestrian space in order to realize a public space that can ultimately improve the quality of life based on guaranteeing people's right to move while also enhancing urban activity. The goal of this study is to develop a pedestrian path evaluation system in order to lay the foundation for data construction leading to the creation of such elegant walking space. First, a basic system was established in keeping with factors and the space, and this system was used as the basic framework of the study. The trends identified in the literature can be divided into eight categories, denoted here as: Walking safety policy, Walking focused plan, Recognition transition, Transportaion system, Activity-linked walking, Facility utilization walking, Nature and history linked walking and Content convergence walking. The macro- and micro-indices and factors mentioned in related studies were synthesized and classified, and the basis for universality and differentiation was established by integrating them. Next, according to the basic composition of the walking system, Walking potential and slope safety in the Safety category, Basic walking connectivity and Traffic linkage in the Efficiency category, Walking arrangement and Rest convenience in the Health category, and Resource connectivity and Activity abundance in the Comfortability category macro evaluation system of the eight categories were established and a corresponding measurement method was developed.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.160-165
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• 2022

In this paper, we have proposed a magnetic resonant 6.78MHz WPT(wireless power transfer) technique which can be applied to a fixed transmitter and a receiver of varying relative distance and coil alignment, Power transmission characteristics are studied with the relative distance and misalignment ration of coil area between the transmitting and receiving coils. The coils are designed with the size of 60×80mm² by direct feeding method, and the characteristics are derived with the maximum relative distance of 50mm and horizontal area misalignment state of 0-40mm misalignment of coil center axis in the XY plane. The power transmission characteristics are compared between the 3D EM simulation and the measured data, and the power transmission shows larger than -3dB performance with the vertical distance of up to 30mm and 50% area misalignmment ratio. This work showsthe transmission characteristics according to relative distance and misalignment state between the cols and that direct feeding has advantage for the short relative distance and small misalignment ratio.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.550-557
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• 2021

With the advent of the fourth industrial revolution, the interest in the internet of things (IoT) in manufacturing is growing, even at foundries. There are several types of process data that can be automatically collected at a foundry, but considerable amounts of process data are still managed based on handwriting for reasons such as the limited functions of outdated production facilities and process design based on operator know-how. In particular, despite recognizing the importance of converting process data into big data, many companies have difficulty adopting these steps willingly due to the burden of system construction costs. In this study, the field applicability of IoT-based devices was examined by manufacturing devices and applying them directly to the site of a centrifugal foundry. For the centrifugal casting process, the temperature and humidity of the working site, the molten metal temperature, and mold rotation speed were selected as process parameters to be collected. The sensors were selected in consideration of the detailed product specifications and cost required for each process parameter, and the circuit was configured using a NodeMCU board capable of wireless communication for IoT-based devices. After designing the circuit, PCB boards were prepared for each parameter, and each device was installed on site considering the working environment. After the on-site installation process, it was confirmed that the level of satisfaction with the safety of the workers and the efficiency of process management increased. Also, it is expected that it will be possible to link process data and quality data in the future, if process parameters are continuously collected. The IoT-based device designed in this study has adequate reliability at a low cast, meaning that the application of this technique can be considered as a cornerstone of data collecting at foundries.

• Tunnel and Underground Space
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• v.32 no.1
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• pp.78-92
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• 2022

In this study, we proposed a diagnostics and assessment model for mining sites that can evaluate the smart mining technology level in a systematic and structured way. For this, the maturity of the smart mining was defined, and detailed assessment items of the diagnostics and assessment model for smart mining were derived by considering the smart factory diagnostics and assessment model (KS X 9001-3) used in the manufacturing industry. While maintaining the existing system, the existing 46 detailed assessment items were modified to be suitable for mining. As a result, a total of 29 detailed assessment items were derived in the areas of promotion strategy, process, information system and automation, and performance. Based on this, a questionnaire was designed to diagnose the level of smart mining technology, and assessment was performed by applying it to domestic iron mines. The level of smart mining technology in the study area was found to be level 2, and it could be inferred that it was about 40% lower than the average smart level of the general manufacturing industry. In addition, by using the developed model, it was possible to recognize the weak points of the mine at each stage of the introduction, operation, and advancement of smart mining, and to suggest investment and improvement directions.