• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.187-192
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• 2021

In this study, Inconel 625 was used as a thermal spray material to prevent dew point corrosion damage to the economizer tube, and sealing treatment was performed after applying the arc thermal spray coating technology. Various electrochemical experiments were conducted in the 0.5 wt% sulfuric acid solution to analyze the corrosion resistance of the thermal spray coating (TSC) layer. After the anodic polarization experiment, the degree of corrosion damage was determined through a scanning electron microscope and EDS component analysis. When measuring the open circuit potential, the effect of the sealing treatment was confirmed through stable potential formation of the TSC+sealing treatment (TSC+Sealing). As a result of the anodic polarization experiment, the passivation region was confirmed in TSC and TSC+Sealing, and corrosion resistance was improved as no corrosion damage was observed. In addition, the corrosion resistance of TSC+Sealing was the best when analyzing the corrosion potential and corrosion current density calculated by Tafel analysis.

• Korean Journal of Plant Resources
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• v.32 no.5
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• pp.486-498
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• 2019

This study was conducted to investigate the leaf growth and flowering characteristics of 85 Hosta cultivars. The 85 cultivars were grown in a pot in Useful Plant Resources Center in Yangpyeong, Korea. H. 'Abiqua Blue Crinkles', H. 'Abiqua Drinking Gourd', H. 'Dancing in the Rain', H. 'Elegance', H. 'Inniswood', and H. 'Venus' were classified as a large size group (> 50 cm), while 27 cultivars including H. 'Abby', H. 'Birchwood Parky's Gold', H. 'Blue Cadet', and H. 'Blue Edge' were classified as a small size group (< 20 cm). The others were classified as a medium size groups. 79% of Hosta cultivars had leaf variegation. Leaf variegation type was divided into 5 types (standard, marginata, mediovarigata, albomaculata, striata). Among them 31 cultivars including H. 'Abby', H. 'Abiqua Moonbeam', and H. 'Atlantis' has a variegation type of marginata in the leaf. 36 cultivars including H. 'Abby', H. 'Abiqua Drinking Gourd', and H.'Abiqua Moonbeam' bloomed in late May and 9 cultivars including H. 'Black Hills', H. 'Boeun', and H. 'Fragrant Bouquet' started to flower on late August. Most flowers were below 3.0 cm in length, while H. 'Avocado' was longest on 10.0 cm. Most flowers have a lavender color group (63.5%), and 14 cultivars of Hosta showed white color group (16.5%). 12 cultivars including H. 'Blue Mouse Ears', H. 'Captain Kirk', and H. 'Fragrant Bouquet' had the fragrance in their flowers. H. 'Cherry Berry' and H. 'Revolution' had a colorful stalk, red and yellow, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4246-4257
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• 2014

The aim of this study was to search for a security strategy and security education program by analyzing the security awareness of universities with and without Department of Military Science. The results of university student's security awareness revealed a normal level of recognition and differences according to region and gender. The recognition of stability of current Korean national security is normally low on average, which suggests that students feel anxiety towards national security. In addition, the North Korea provocation influence on national security has been recognized highly (score of 4.33 on average). The national security awareness of university students in the case of whether establishing a Dept. of Military Science or not showed a normal level, which revealed a score of 3.44, and differed according to region, gender and recruitment, and had a relationship with the recognition of Dept. of Military Science management. Therefore, the political consideration of security authorities is in strong demand to improve the security awareness of general university students, and have an influx of great human resources by advertising the educational contents, advantages and future career of Dept. of Military Science students.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.631-638
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• 2016

A mariner cadet gains the ability to identify and avoid potential collisions with other ships through ARPA/Radar simulation education. This research surveyed first domestic and overseas's rules (e.g., MOMAF's Standard, the STCW Convention, etc.) of the simulation education, upon investigation the only content and timing of this simulation-based education are specified according to these rules, and maritime education institutions issue the related certification autonomously after a student has taken the simulation because no simulation education module exists to further guide the ARPA/Radar simulation. As a result, it is difficult for students to acquire consistent maritime ability through ARPA/Radar simulation. This paper discusses standardization of these education modules to produce more consistent mariner ability, and verify the degree of improvement of education that would be achieved by enacting the proposed education module. The simulation education system used in maritime institutions in Korea was investigated, and scenarios reflecting traffic flow in actual waterways was proposed based on marine traffic surveys so teaching modules can educate/assess more effectively based on core marine abilities. Improvements in education and training were also verified using data collected over 2 years based on a standardized module. Each education institution can enact an effective, systematic education approach using standardized ARPA/Radar education modules proposed in this paper, and this can set a foundation to contribute to safer vessel navigation by improving maritime abilities.

• Asian Journal of Turfgrass Science
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• v.15 no.2
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• pp.39-50
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• 2001

This research was designed to develop the rapid propagation technology of zoysiagrass using carpet production and to provide turf-growing farmers with efficient cultivation methods thor carpet production. Turfgrass cultivar tested in cadet production by seeding was Z. japonica cv. Zenith. Since the surface coverage rate reached to 85% in 2 months after seeding at the rate 6g/$m^2$ in the early part of July, carpet production using ‘Zenith’seeds would be possible to produce within within the same year. Thrfgrasses tested in carpet production by vegetative propagation were Z. japonica, medium type Z. matrella, fine type Z. matrella, and medium type Z. japonica. Planting rates of vegetative parts (sprigs) were 1.2L/$m^2$, 2.4L/$m^2$, 2.5L/$m^2$, and 5L/$m^2$. Two different sizes of sprig were used; 1~2 nodes and 3~4 nodes. Surface coverage rate was 90% in one year after planting at the rate of 2.5L sprigs of medium type Z. japonica. Therefore, the use of sprigs with 3~4 nodes at the planting rate of 2.5L would be suitable for the carpet prodcution. Three months old zoysiagrass carpet (Zenith) was overseeded with Kentucky bluegrass, perennial ryegrass, and tall fescue at two different overseeding rate. Surface coverage rate was the highest (80%) at the plot overseeded with perennial ryegrass that showed the earliest germination. Suitable overseeding species for the rapid sod formation at the early stage of establishment were tall fescue and perennial ryegrass and desirable overseeding time was from early to middle of September.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.946-954
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• 2022

More than half of barges have been surveyed and designated as an "unmanned barge". The main advantage of the unmanned barge is that it can carry more cargo equivalent to 25 percent of freeboard compared to that of a manned barge. In contrast, it needs an onboard crew barge because the bargeman is in charge of several tasks during sailing such as mooring or unmooring barges to or from a wharf, dropping and heaving up an anchor and turning on and of navigational lights and shapes. The instant recognition is that a tug assume the responsibility of operating a barge; however, different situations exist in which the shipper, as the operator of the barge, hires a tug. Although a tug might be a carrier of a barge under a specific contract, the master of the tug should fulfill his duty to complete its voyage. Most masters are not provided with the particulars of a barge and the information regarding the bargemen onboard, which is believed not to respect the master's authority and lead to an unintended violation of relevant laws. This paper presents three recommendations for resolving these issues: the policy approach for changing unmanned barges to manned barges, issuing a minimum safe manning certificate, and providing the master of tug information on the barge and the crew onboard. Thus, the proposed approach can be expected to improve the crew's working conditions, diminish the violation of the maximum number of persons onboard the barge, and ensure the authority of the master of tug through such recommendations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.97-107
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• 2024

Despite the rapid advancement in image recognition technology, achieving perfect digitization of tabular documents and handwritten documents still challenges. The purpose of this study is to improve the accuracy of digitizing the logbook by correcting errors by utilizing associated rules considered during logbook entries. Through this, it is expected to enhance the accuracy and reliability of data extracted from logbook through OCR programs. This model is to improve the accuracy of digitizing the logbook of the training ship "Saenuri" at the Mokpo Maritime University by correcting errors identified after Optical Character Recognition (OCR) program recognition. The model identified and corrected errors by utilizing associated rules considered during logbook entries. To evaluate the effect of model, the data before and after correction were divided by features, and comparisons were made between the same sailing number and the same feature. Using this model, approximately 10.6% of errors out of the total estimated error rate of about 11.8% were identified, and 56 out of 123 errors were corrected. A limitation of this study is that it only focuses on information from Dist.Run to Stand Course sections of the logbook, which contain navigational information. Future research will aim to correct more information from the logbook, including weather information, to overcome this limitation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.4
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• pp.324-331
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• 2024

The height of large car and truck carriers from the keel to the wheel house is 44 ~ 46 m, and as the car-carriers increases in size, it exhibits the 'top heavy' characteristic, where the upper section is heavier than the lower section. This study aims to estimate the maximum outward heel angle of the Golden Ray car-carrier (G-ship) during turning maneuvers for accident investigation and the prevention of similar accidents. The theoretically calculated maximum outward heel is 7.5° (at 19 kn, rudder angle 35°) with a GM of +3.0 m or higher, and 16.7° with a GM of +1.85 m. Meanwhile the experimentally modified maximum outward heel is 10.5° (at 19 kn, rudder angle 35°) with a GM of +3.0 m or higher, and 23.3° with a GM of +1.85 m. The G-ship is maneuvered during an accident at a speed of 13 kn, at starboard rudder angle of 10° to 20°, it changes course from 038°(T) to 105°(T) based on the instructions of the on-board pilot. At this time, the maximum outward heel is estimated to be between 7.8° and 10.9° at the port side, which is 2.2 times higher than the normal outward heel. In the IS code, cargo ships are required to exhibit a minimum GoM of +0.15 m or more. The maneuvered G-ship exhibits a GoM of +1.72 m. It is not maneuvered because it fails to satisfy the international GoM criteria and because its GoM is insufficient to counteract the heeling moment during the maneuver. This study is performed based on accident-investigation results from the Korea Maritime Safety Tribunal and the USCG.

• Polymer(Korea)
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• v.36 no.6
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• pp.776-788
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• 2012

Octa[8-{4-(4'-cyanophenylazo)phenoxy}]octyl and octa[8-{4-(4'-cyanophenylazo)phenoxycarbonyl}]heptanoated disaccharide derivatives were synthesized by reacting cellobiose, maltose, and lactose with 1-{4-(4'-cyanophenylazo) phenoxy}octylbromide or 1-{4-(4'-cyanophenylazo)phenoxycarbonyl}]heptanoyl chloride, and their thermotropic liquid crystalline and photochemical phase transition behavior were investigated. All the {(cyanophenylazo)phenoxy} octyl disaccharide ethers (CADETs) formed monotropic nematic (N) phases, whereas all the {(cyanophenylazo) phenoxycarbonyl}heptanoated disaccharide esters (CADESs) exhibited enantiotropic N phases. Compared with CADETs, CADESs showed higher isotropic (I)-to-N phase transition temperatures. Photoirradiation of the disaccharide derivatives in a glass cell or in a cell with a rubbed polyimide (PI) alignment layer at a N phase resulted in disappearance of the N phase due to trans-cis photoisomerization of azobenzene, and the initial N phase was recovered when the irradiated sample was kept in the dark because of cis-trans thermal isomerization and reorientation of trans-azobenzenes. The rates of the photochemical N-I and the thermal I-N phase transition of disaccharide derivatives in a cell with a rubbed PI alignment layer were faster than those in a glass cell, and were significantly different from those observed for the monomesogenic compounds containing cyanoazobenzene and the 4-{4'-(cyanophenylazo)phenoxy}octyl glucose and cellulose ethers. The results were discussed in terms of difference in cooperative motion of azobenzene groups due to the flexibility of the main chain, the number of mesogenic units per repeating units, and the distance between the azobenzene groups.