• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.733-738
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• 2021

Recently, people's interest in marine leisure has been increasing, and research and development on leisure boats are actively being carried out to pioneer overseas markets. These days, the materials used for leisure boats are fiber-reinforced plastic (FRP) and aluminum alloy. However, FRP is hygroscopic and causes environmental problems, and aluminum alloy has high thermal conductivity and fire susceptibility. Therefore, titanium alloy is being adopted as a material for leisure boats instead. In this study, hull thicknesses and design pressures were calculated while considering dynamic effects for titanium boats. Four sets of rules and regulations were used: ISO 12215-5, RINA Pleasure Yacht, LR Special Service Craft, and KR High-speed Light Craft. The maximum bottom slamming loads were in the order of ISO, KR, LR, and RINA, and the required hull thicknesses were in the same order. This research might be helpful for understanding the rules, regulations, and overseas export of leisure boats.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.41-52
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• 2021

During atmospheric ascent of a launch vehicle, airborne acoustic loads act on the vehicle and its effect becomes pronounced at transonic speed. In the present study, acoustic loads acting on a hammerhead launch vehicle at a transonic speed have been analyzed using ��-ω SST based IDDES and the results including mean Cp, Cprms, and PSD are compared to available wind-tunnel test data. Mesh dependency of IDDES results has been investigated and it has been concluded that with an appropriate turbulence scale-resolving computational mesh, the characteristic flow features around a transonic hammerhead launch vehicle such as separated shear flow at fairing shoulder and its reattachment on rear body as well as large pressure fluctuation in the region of separated flow behind the boat-tail can be predicted with reasonable accuracy for engineering purposes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.235-243
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• 2022

A total of 97,623 ships were registered in Korea in 2019. Among these, 65,835 vessels, accounting for approximately 67 % of the total number of ships, were registered as fishing vessels. As with the proportion of fishing vessels, the frequency of marine accidents is also high. In 2020, 2,331 of 3,535 accidents occurred on fishing vessels. Hence, various institutional arrangements are required for improving the safety of domestic fishing vessels. In this study, we examined domestic and international regulations on domestic and foreign control performance related to fishing boats for improving the safety of fishing boats. Additionally, the ratio of the rudder area of 153 fishing boats operating in Korea was investigated to examine the current status of the rudder area design of fishing boats whose design standards have not been clearly established compared to fishing boats. Resultantly, we statistically confirmed that most fishing boats were designing rudder areas because they did not meet international standards. In the future, these analysis results can be used as basic data to prepare rudder area design standards for improving the maneuvering performance of domestic fishing boats.

• The Journal of Fisheries Business Administration
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• v.52 no.4
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• pp.1-11
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• 2021

This study is to investigate the determinants of consumption expenditure by considering potential expenditure factors such as socioeconomic, fishing village tourism behavior, motivation for visits, and optional attributes of tourists at Muchangpo webfoot octopus and finespotted flounder festival in Boryeong. The analysis data are 300 questionnaires of visitors to the festival during the 2018 Muchangpo Mysterious Sea Road Webfoot Octopus and Finespotted Flounder Festival from March 17 to April 8, 2018. As a result of analyzing the factors of consumption expenditure of tourists to the festival in Boryeong, socioeconomic factors such as gender and residential groups outside Chungcheong-do have a positive (+) effect on consumption expenditure. Among the factors of fishing village tourism behavior, the only number of days of stay more than one night has a positive (+) effect on consumption expenditure. In addition, in the analysis of factors for motivation to visit the festival, fun/interest and simple rest/leisure have a significant positive (+) effect on expenditure whereas stress relief have a negative (-) effect on expenditure. In the analysis of the factors of festival selection attributes, tourism facilities has a significant positive (+) effect on expenditure, but natural scenery and excellent natural scenery show a significant negative (-) effect on expenditure. The main implications that can be obtained from the results of this study are as follows. First, it suggests that the promotion should be actively conducted outside of Chungcheong Province in order to achieve the original purpose of revitalizing the local economy from the Muchangpo webfoot octopus and finespotted flounder festival. Second, it indicates that there should be a variety of unique high-quality festival programs differentiated from other local festivals, promoting the existence of simple rest/leisure facilities rather than webfoot octopus boat fishing experiences or natural scenery (i.e., mysterious road and sunset) in order to attract festival tourists' spending at the Muchangpo webfoot octopus and finespotted flounder festival.

• Parasites, Hosts and Diseases
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• v.60 no.5
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• pp.361-365
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• 2022

We report a species of diplostomid fluke recovered from 3 carcasses of wild Korean raccoon dog, Nyctereutes procyonoides koreensis, in Korea. A total of 107 diplostomid flukes were recovered from the small intestines of Korean raccoon dogs, which were obtained from the Gangwon Wildlife Medical Rescue Center. Worms fixed with 10% neutral formalin were subjected to microscopic observation and those fixed in 70% ethanol were used for molecular genomic analysis. The worm was divided into 2 separate parts, forebody and hindbody, with a total length of 3,020-4,090 (3,855) ㎛ and a width of 1,210-1,770 (1,562) ㎛. The boat-shaped forebody has a pair of characteristic tentacular appendage, 2 suckers, holdfast organ, and vitelline follicles. The oval to cylindrical hindbody has reproductive organs. The ovary was round or elliptical and located in the anterior of the testes. Two large testes were slightly segmented and tandemly arranged, occupying almost half of hindbody. The short uterus contained a relatively small number of unembryonated eggs sized 130-140×85-96 ㎛. The partial sequence of 18S rRNA of this fluke was consistent with Alaria alata. Based on the morphological and molecular characteristics, the diplostomid flukes recovered from the small intestine of Korean raccoon dogs were identified as A. alata (Digenea: Diplostomidae).

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.439-446
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• 2022

Efforts to reduce carbon dioxide(CO₂) emissions are being carried out due to climate environmental problems. Eco-friendly ships are also being developed, and various energy saving measures have been developed and applied. In ships, researches have been conducted in various fields such as electric propulsion system and energy saving devices. In addition, the development of ships using various renewable energy, such as kite using wind power and wind power generation, has been carried out. This paper proposes a plan to use renewable energy for ships by applying wave generators to small ships. In 2016, 130 small domestic ships drifted by sea due to discharge of starting storage batteries, and discharge cases accounted for the largest portion of the causes of domestic ship accidents. This is due to the excessive use of storage batteries for starting the main engine by departing in a weak storage battery state for small ships. Accordingly, two type wave power generators - opened flow wave power generator and enclosed vibrator type wave power generator - are developed for charging a starting storage battery when the ships are stationary at sea or port. Opened flow wave power generator utilizes the flow of fluid in the ship by using wave induced ship motion. Enclosed vibrator type wave power generator utilizes the pendulum kinetic energy located in a ship due to wave induced ship motion.

• Industry Promotion Research
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• v.7 no.1
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• pp.75-80
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• 2022

Cui Bu (1454~1504 BC), named Yuanyuan, named Jinnan. Served as the deputy manager of the Korean King Chosun Hongwenguan (fifth grade official). In 1487, on the way to Jeju Island to perform official duties, because his father died, he went home from the funeral on the third day of the first lunar month in 1488, but was unfortunately on the way. Encountered a storm, and drifting at sea for nearly half a month, he landed at the "Linhai County Boundary of Taizhou Prefecture, Zhejiang Province, Datang Kingdom" (now Sanmen County). Later, Cui Bu went to Hangzhou by land near Taizhou, where he landed, then via Hangzhou, took a boat along the Beijing-Hangzhou Grand Canal to Beijing, and from Beijing by land through Shanhaiguan, and returned to his country via the Yalu River. Cui Bu stayed in China for four and a half months, 136 days, and traveled nearly 9,000 miles. After returning to China, he wrote the book "Piaohailu" in Chinese. This diary-style book has a total of more than 50,000 characters, covering politics, military, economics, culture, transportation, and local customs in the early years of Hongzhi in the Ming Dynasty. The situation is an important document for studying China's Ming Dynasty coastal defense, political system, justice, canals, cities, topography, and folklore.

• 한국체육학회지인문사회과학편
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• v.53 no.2
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• pp.531-540
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• 2014

The purpose of this study was to investigate the differences between two inflatable kayak by recording performance related variables during the kayak forward stroke motion. A total of 5 elite high school kayak players were recruited to participate while their kinematics and muscle activations were recorded while performing inside their high school swimming pool. Boat velocity, boats swaying angle, the average angular velocity and were used to evaluate the boats performance. The player's trunk rotational range of motion, knee flexion-extension angle range of motion, maximum trunk rotation angle, the knee flexion-extension angular velocity, and the upper and lower limb muscle activations were calculated and analyzed for the player's efficiency evaluation. There were no significantly different variables for the player's kinematics and their muscle activations for the two conditions. The B kayak was significantly faster than the A kaya. In addition there were no significant differences between the remaining variables for the two kayaks. In conclusion, the B kayak was faster than the A kayak, but neither of the kayaks had an influence on the player's performance variables.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.54-55
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• 2020

In 4th Industrial Revolution, technologies such as artificial intelligence, Internet of Things, and Big data are closely related to the maritime industry, which led to the birth of autonomous vessels. Due to the technical characteristics of the current vessel, the speed cannot be suddenly lowered, so complex communication such as the help of a tug boat, boarding of a pilot, and control of the vessel at the onshore control center is required to berth at the port. In this study, clustering analysis was used to resolve how to establish control criteria for vessels to enter port when autonomous vessels are operating. K-Means clustering was used to quantitatively stage the arrival pattern based on the accumulated AIS(Automatic Identification System) data of the incoming vessel, and the arrival phase using SOG(Speed over Ground), COG(Course over Ground), and ROT(Rate of Turn) Was divided into six phase.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.958-963
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• 2023

Lately, there has been increasing research on the prediction of motion performance using artificial intelligence for the safe design and operation of ships. However, compared to conventional ships, research on small fishing boats is insufficient. In this paper, we propose a model that estimates the motion response essential for calculating the motion performance of small fishing boats using a deep neural network. Hydrodynamic analysis was conducted on 15 small fishing boats, and a database was established. Environmental conditions and main particulars were applied as input data, and the response amplitude operators were utilized as the output data. The motion response predicted by the trained deep neural network model showed similar trends to the hydrodynamic analysis results. The results showed that the high-frequency motion responses were predicted well with a low error. Based on this study, we plan to extend existing research by incorporating the hull shape characteristics of fishing boats into a deep neural network model.