• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.330-336
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• 2017

This study performs a root cause analysis of the sticking that occurs in the hydraulically actuated wet type multi-disc friction clutch in a ship's diesel engine propulsion system that uses rubber elastic coupling. The fishbone method was used to study the sticking through dismantling investigation of the reduction gear and clutch, investigation of the components, and onboard system tests including nondestructive testing. The friction plate sticking is caused by the slip due to friction heat resulting from the leakage of control oil through cracks in the assembled hollow shaft. The friction plate cooling oil also leaks simultaneously through the crack, and partial sticking occurs due to the hot spots in the friction plates. These are caused by insufficient amount of cooling oil due to oil leakage.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.709-716
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• 2020

In social media, when posting a post, tag information of an image is generally used because the search is mainly performed using a tag. Users want to expose the post to many people by attaching the tag to the post. Also, the user has trouble posting the tag to be tagged along with the post, and posts that have not been tagged are also posted. In this paper, we propose a method to find an image similar to the input image, extract the label attached to the image, find the posts on instagram, where the label exists as a tag, and recommend other tags in the post. In the proposed method, the label is extracted from the image through the model of the convolutional neural network (CNN) deep learning technique, and the instagram is crawled with the extracted label to sort and recommended tags other than the label. We can see that it is easy to post an image using the recommended tag, increase the exposure of the search, and derive high accuracy due to fewer search errors.

• Polymer(Korea)
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• v.35 no.3
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• pp.223-227
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• 2011

Stimuli-responsive polymers have been investigated as the materials playing the critical roles in various applications. Thermoresponsive graft copolymers, poly (N-isopropylacrylamide)-g-hyaluronic acid (PNIPAAm-g-HA) and elastin-like peptide-g-hyaluronic acid (ELP-g-HA), were synthesized by coupling carboxylic polymers (PNIPAAm-COOH or ELP) to biocompatible HA through amide linkages. Thermoresponsive behavior was observed in both the copolymers, and the results of turbidity measurement were consistent with the results of rheological examination. Among the two copolymers, the ELP graft copolymer shows less cooperative LCST transition than the PNIPAAm case. As the content of graft chains of PNIPAAm and ELP increases, viscosity increases, and the increase was larger in PNIPAAm case at a graft content. These results shows us that the introduction of grafts provides thermosensitivity to biocompatible HA, whose characteristics can be engineered.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.129-132
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• 1998

A new one-channel phased-array quadrature RF coil is developed for spine MR imaging. Quadrature RF coils for MRI have been used to improve the signal-to-noise ratio (SNR) by$"\squt{2}"$ using two orthogonal RF coils in combination. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of reduced-size RF coil elements. Two schemes proposed for the new phased-array quadrature RF coil are:(1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive-only mode, and tested by phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.d RF coil.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.17-28
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• 2021

Recently, eVTOL, the next-generation of eco-friendly transportation, has been in the spotlight due to global warming along with traffic jams in large cities of many countries. This study benchmark the external features of Hyundai Motors S-A1, a compound eVTOL combined fixed and tilt rotors among many types of eVTOLs, to create the basic configuration using reverse design techniques. Basic configurations were created using CATIA and aerodynamic analyses were performed using the aircraft design and aerodynamic analysis programs, OpenVSP, XFLR5, and the aircraft wetted area, drag, and lift were calculated after selecting the airfoil, incidence angle, and dihedral and anhedral angles through trade study. Also, required powers were estimated for completing the given mission profile and components weight and the total weight were predicted using the estimation formula and data survey.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.428-439
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• 2021

A spray-on membrane is a material composed of a polymer, and is a spray-type material that is expected to be able to replace materials such as existing shotcrete or sheet membrane for support or waterproofing purposes. In the previous studies, it is expected that the thickness of the support material such as shotcrete can be reduced if the spray-on membrane is additionally installed on the existing cement-based support materials. In this study, a three-point bending test was performed by a spray-on membrane on the high-performance shotcrete on the outside, and comparison was made between the case where high-performance shotcrete and a spray-on membrane were installed. As a result of comparing the values calculated through the standard test and the real-size bending test, there was no significant difference in terms of flexural strength, but it was found that there was a difference in flexural toughness.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.103-109
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• 2023

The Safe Life is an essential subject of education introduced in the 2015 revised curriculum for first and second graders of elementary school to cultivate safety awareness. This study aims to explore the relationship between concepts and concepts that are important in the Safe Life textbook using a keyword network analysis. The results indicate that the areas of life safety, traffic safety, and disaster safety are emphasized in terms of topics in the textbook. The teaching and learning methods for the Safe Life education are mainly based on "experience" and "practice," and the most common teaching materials are card games and sticky stickers. Based on the findings, we suggest maintaining the experience-oriented safety education approach and diversifying the teaching and learning materials and methods to incorporate various safety education areas.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.941-946
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• 2023

To improve the lift, cruise speed, and range of eVTOL aircraft, which are being considered as future transportation vehicles, this paper introduces the concepts of Tilt Rotor and Tandem Wing to the aircraft. We developed an aircraft and conducted flight experiments to obtain flight videos and flight logs. The results of the analysis of the flight videos and flight logs showed that the aircraft's moment was excessively forward and the attitude was not recovered. To address this problem, we modified the wing incidence angles and surface areas in XFLR5 to obtain the optimal pitching moment coefficients to ensure vertical stability. We then analyzed the redesigned aircraft, developed using CATIA, through XFLR5. The results of this study provide valuable insights, suggesting that the incorporation of Tilt Rotor and Tandem Wing designs can contribute to achieving stable pitching moment coefficients. This innovative approach offers a promising avenue to significantly enhance vertical stability in UAM vehicles, paving the way for future advancements in the field.

• Korean Journal of Environment and Ecology
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• v.36 no.5
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• pp.481-495
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• 2022

This study was designed to identify the actual state of naturalized plants and invasive alien species that cause disturbances to the ecosystem, plants which are introduced after forest restoration, and explore the implications resulting from the project. Onsite examination included 29 sites which have been subjected to forest restoration by the Korea Forest Service. Once these were chosen, activity took place twice a year in the spring (May-June) and in the summer (August-September) in 2020 and 2021. Areas not relevant to the project sites were excluded from this activity so that we could identify the plants that could be understood to have been introduced or brought into the site after the actual forest restoration. And the correlation was analyzed, between the naturalized flora within the project sites and the working types applied to the site through confirmation of completion of the restoration project. The naturalized plants appearing on the entire site cover a total of 109 taxa, which includes 29 families, 80 genera, 108 species and 1 subspecies, while invasive plants included 3 families, 7 genera and 8 species. The number of classifications and the naturalization rate gradually decreased over time, after the project. While there was no significant difference between the number of classification groups and the naturalization rate for naturalized plants between project sites, given the number of taxa of naturalized plants, organized by type of damage, there were relatively more naturalized plants that appeared in the severed section of the Baekdudaegan Mountain Range, as well as at quarry and facility sites. Seeding apparently results in naturalization rates as high as 15.545%, on average, based on comparisons of naturalization rates by sowing, seeding, planting, herb planting, and sod pitching channels, all of these being methods of vegetation for planting/greening of bareland and slopes within the project areas. With no seeding, it was 9.167%, higher than the average. As for other vegetation, there was no significant difference depending on application of the working type. This means that unlike the plants subjected to planting, the working type of seed planting which makes it difficult to identify whether a certain plant is a naturalized plant greatly affects the introduction of naturalized plants to the restoration sites, even when using herb planting and sod pitching to control plants and results. Therefore the study suggests that there be inspection by experts of seeds when sowing within restoration sites. The results of this study suggest good practices that will help to direct effective vegetation restoration and follow-up management.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.461-466
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• 2011

In genetic and molecular breeding studies of plants, researchers need to design various kinds of primers based on their research purposes. So far many kinds of web- or script-based non-commercial programs for primer design are available. Because most of them do not include user interface for multipurpose usage including gene structure prediction and direct target selection on sequences, it has been a laborious work to design primers targeting on the exon or intron regions of interesting genes. Here we report a primer designing graphic user interface program, Pickprimer, that includes gene structure prediction and primer design modules by combining source codes of the Spidey and Primer3 programs. This program provides simple graphic user interface to input sequences and design primers. Genomic sequence and mRNA or coding sequence of genes can be copy and pasted or input as fasta or text files. Based on alignment of the input sequences using the Spidey module, a putative gene structure is graphically visualized along with exon-intron sequences of color codes. Primer design can be easily performed by dragging mouse on the displayed sequences or input primer targeting position with desirable values of primers. The output of designed primers with detailed information is provided by the Primer3 module. PCR evaluation of 24 selected primer sets successfully amplified single amplicons from six Brassica rapa cultivars. The Pickprimer will be a convenient tool for genetic and molecular breeding studies of plants.