• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.47-58
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• 2022

This research presented development contents for application of realistic content approach study that can experience T-ball sports used in regular physical education classes at indoor space with screen. The scope of application can be used for ball sports training in virtual reality sports room of elementary and junior high schools. The approach process presents an appropriate approach system for sustainable training education which is to improve T-ball sports training to target users through consultation-based collaboration with sports experts and T-ball leaders, focusing on basic training content of T-ball textbooks. In other words, the training mode was designed to induce immersion in T-ball sports classes and provide natural basic training for students at elementary schools rather than simply experience-based realistic content. The developed training content provided basic attack training according to weekly differentiated curriculum, and the approach process of training mode by difficulty level was presented to allow the user to improve the training by the degree of difficulty. In addition, the match mode approach process that reflects the game rules of T-ball sports was presented. This study can be presented as a reference production case that can be used to improve basic training and physical exercise of ball sports for industries related to development of realistic content.

• Communications of Mathematical Education
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• v.35 no.4
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• pp.527-546
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• 2021

The purpose of this study is to reveal what mathematics teachers focus on and how they assess students' thinking during lessons enacted. For this purpose, we googled and searched internet sites to collect formative assessment materials for the year 2014 to 2019. The formative assessment tasks data were analyzed according to the levels cognitive demand levels and tasks suggested in textbooks in terms of degrees to which how they are related. The data analysis suggested as follows: a) most of the formative assessment tasks were at the low-level, in particular, PNC level tasks that require applying particular procedures without connections to concepts and meaning underlying the procedures, b) the assessment tasks appeared to be very similar to the tasks suggested in the secondary mathematics textbooks, and c) it seemed that 3 types of formative assessment, observation notes, self-assessment, and peer-assessment were dominantly utilized during mathematics lessons and these different types of formative assessment were employed apparently to find out whether students participated actively in class and in group activity, not how they go through understanding or thinking processes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1100-1109
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• 2022

Herein, a case study was conducted on the bilge pumping performance of a 24,000TEU class container ship with an overall length of 400m. Although the bilge system of the 24,000TEU class container ship was designed in accordance with the rule requirements of the Classification Society, the bilge system did not satisfy the 2 m/s requirements of SOLAS Reg.II-1/35-1 under the rated flow rate and maximum flow rate conditions of the bilge pump installed in the ship. In particular, assumptions were made that No.1 ~ No.4 cargo holds were flooded and filled entirely by sea water and the evaluation of bilge pumping performance had been performed for No.1 ~ No.4 cargo holds. According to the evaulation results of the, the mean water velocity at the main bilge pipe for No.2, No.3, and No.4 cargo holds did not meet the 2 m/s criterion. To resolve this problem, in this study, the branch bilge pipe in each cargo hold was changed from 150A to 200A and the mean water velocity at the main bilge pipe for No.2, No.3, and No.4 was calculated as 2.479m/s, 2.476m/s, and 2.459m/s, respectively.

• Membrane Journal
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• v.32 no.6
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• pp.367-382
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• 2022

Numerous metal-organic frameworks (MOFs) produced by periodic combinations of organic ligands and metal ions or metal-oxo clusters have led the way for the creation of energy-efficient membrane-based separations that may serve as viable replacements for traditional thermal counterparts. Although tremendous progress has been made over the past decade in the synthesis of polycrystalline MOF membranes, only a small number of MOFs have been exploited in the relevant research. Intercrystalline defects, or nonselective diffusion routes in polycrystalline membranes, are likely the reason behind the delay. Postsynthetic modifications (PSMs) are newly emerging strategies for providing polycrystalline MOF membrane diversity by leveraging advanced membranes as a platform and improving their separation capabilities via physical and/or chemical treatments; therefore, neither designing and developing MOFs nor tailoring membrane synthesis techniques for focused MOFs is necessary. In this minireview, seven subclasses of PSM techniques that have recently been adapted to polycrystalline MOF membranes are outlined, along with obstacles and future directions.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.2
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• pp.55-68
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• 2024

Plant engineering companies create or refer to requirements documents for each related field, such as plant process/equipment/piping/instrumentation, in different engineering departments. The process-related requirements document includes not only a description of the process but also the requirements of the equipment or related facilities that will operate it. Since the authors and reviewers of the requirements documents are different, there is a possibility that inconsistencies may occur between equipment or parts design specifications described in different requirement documents. Ensuring consistency in these matters can increase the reliability of the overall plant design information. However, the amount of documents and the scattered nature of requirements for a same equipment and parts across different documents make it challenging for engineers to trace and manage requirements. This paper proposes a method to analyze requirement sentences and calculate the similarity of requirement sentences in order to identify semantically identical sentences. To calculate the similarity of requirement sentences, we propose a named entity recognition method to identify compound words for the parts and properties that are semantically central to the requirements. A method to calculate the similarity of the identified compound words for parts and properties is also proposed. The proposed method is explained using sentences in practical documents, and experimental results are described.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.155-163
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• 2024

As the demand for reducing carbon emissions increases, efforts to reduce the usage of fossil fuels and research on renewable energy are also increasing. Among the various renewable energy harvesting techniques, the floating offshore wind turbine has several advantages. Compared to other technologies, it has fewer installation limitations due to interference with human activity. Additionally, a large wind turbine farm can be constructed in the open ocean. Therefore, it is important to conduct motion analysis of floating offshore wind turbines in waves during the initial stage of conceptual design. In this study, a frequency motion analysis was conducted on a semi-submersible type floating offshore wind turbine. The analysis focused on the effects of varying trim on the motion characteristics. Specifically, motion response analysis was performed on heave, roll, and pitch. Natural period analysis confirmed that changing the trim angle did not significantly affect the heave and pitch motions, but it did have a regular impact on the roll motion.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.214-224
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• 2024

Sonobuoys are disposable devices that utilize sound waves for information gathering, detecting engine noises, and capturing various acoustic characteristics. They play a crucial role in accurately detecting underwater targets, making them effective detection systems in anti-submarine warfare. Existing sonobuoy deployment methods in multistatic systems often rely on fixed patterns or heuristic-based rules, lacking efficiency in terms of the number of sonobuoys deployed and operational time due to the unpredictable mobility of the underwater targets. Thus, this paper proposes an optimal sonobuoy placement strategy for Unmanned Aerial Vehicles (UAVs) to overcome the limitations of conventional sonobuoy deployment methods. The proposed approach utilizes reinforcement learning in a simulation-based experimental environment that considers the movements of the underwater targets. The Unity ML-Agents framework is employed, and the Proximal Policy Optimization (PPO) algorithm is utilized for UAV learning in a virtual operational environment with real-time interactions. The reward function is designed to consider the number of sonobuoys deployed and the cost associated with sound sources and receivers, enabling effective learning. The proposed reinforcement learning-based deployment strategy compared to the conventional sonobuoy deployment methods in the same experimental environment demonstrates superior performance in terms of detection success rate, deployed sonobuoy count, and operational time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.105-111
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• 2024

This paper deals with the minimum linear arrangement(MinLA) of a lattice graph, to which an approximate algorithm of linear complexity O(n) remains as a viable solution, deriving the optimal MinLA of 31,680 for 33×33 lattice. This paper proposes a partitioning arrangement algorithm of complexity O(1) that delivers exact solution to the minimum linear arrangement. The proposed partitioning arrangement algorithm could be seen as loading boxes into a container. It firstly partitions m rows into r₁,r₂,r₃ and n columns into c₁,c₂,c₃, only to obtain 7 containers. Containers are partitioning with a rule. It finally assigns numbers to vertices in each of the partitioned boxes location-wise so as to obtain the MinLA. Given m,n≥11, the size of boxes C₂,C₄,C₆ is increased by 2 until an increase in the MinLA is detected. This process repeats itself 4 times at maximum given m,n≤100. When tested to lattice in the range of 2≤n≤100, the proposed algorithm has proved its universal applicability to lattices of both m=n and m≠n. It has also obtained optimal results for 33×33 and 100×100 lattices superior to those obtained by existing algorithms. The minimum linear arrangement algorithm proposed in this paper, with its simplicity and outstanding performance, could therefore be also applied to the field of Very Large Scale Integration circuit where m,n are infinitely large.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.4
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• pp.303-314
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• 2024

Recently, the consecutive shield tunnel boring machine (TBM) has gained attention for its potential to enhance TBM penetration rates. However, its development requires a thorough risk assessment due to the unconventional nature of its equipment and hydraulic systems, coupled with the absence of design or construction precedents. This study investigated the causal relationships between four accidents and eight relevant sources associated with the consecutive shield TBM. Subsequently, risk levels were determined based on expert surveys and a risk matrix technique. The findings highlighted significant impacts associated with collapses or surface settlements and the likelihood of causal combinations leading to misalignment. Specifically, this study emphasized the importance of proactive mitigation measures to address collapses or surface settlements caused by inadequate continuous tail void backfill or damaged thrust jacks. Furthermore, it is recommended to develop advanced non-destructive testing technology capable of comprehensive range detection across helical segments, to design a sequential thrust jack propulsion system, and to determine an optimal pedestal angle.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.667-685
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• 2022

This paper aims to investigate 4D printing materials for soft robots. 4D printing is a targeted evolution of the 3D printed structure in shape, property, and functionality. It is capable of self-assembly, multi-functionality, and self-repair. In addition, it is time-dependent, printer-independent, and predictable. The shape-shifting behaviors considered in 4D printing include folding, bending, twisting, linear or nonlinear expansion/contraction, surface curling, and generating surface topographical features. The shapes can shift from 1D to 1D, 1D to 2D, 2D to 2D, 1D to 3D, 2D to 3D, and 3D to 3D. In the 4D printing auxetic structure, the kinetiX is a cellular-based material design composed of rigid plates and elastic hinges. In pneumatic auxetics based on the kirigami structure, an inverse optimization method for designing and fabricating morphs three-dimensional shapes out of patterns laid out flat. When 4D printing material is molded into a deformable 3D structure, it can be applied to the exoskeleton material of soft robots such as upper and lower limbs, fingers, hands, toes, and feet. Research on 4D printing materials for soft robots is essential in developing smart clothing for healthcare in the textile and fashion industry.