• Journal of Navigation and Port Research
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• v.46 no.2
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• pp.92-98
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• 2022

Maritime accidents result in enormous economic loss and loss of life; thus, such accidents must be prevented, and risks must be managed to prevent these occurrences Risk management must be based on statistical evidence such as variables. Because calculating when variables increase statistically can be difficult, compressing the designated variables is necessary to use the maritime accident data in Korea. Thus, in this study, variables of marine accident data are compressed using statistical methods. The date, ship type, and marine accident type included in all maritime accident data were extracted, the number of optimal variables was confirmed using the hierarchical clustering analysis method, and the data were compressed. For the compressed variables, the validity of the data use was statistically confirmed using analysis of variance, and the data of the variables identified using the variable compression method were designated. Consequently, among the monthly and yearly data, statistical significance was confirmed in yearly data, and compression was possible. The significance of the data was confirmed in six and eight types of ships and accidents, respectively, and these were compressed. These results can be directly used for prevention or prediction based on past maritime accident data. Additionally, the data range extracted from past maritime accidents and the number of applicable data will be studied in the future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.160-161
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• 2022

Hydrogen is bridge fuel with high energy content and environmentally friendly to satisfy the stringent IMO regulation relating to greenhouse gas (GHG) emissions. There is growing interest in hydrogen in numerous nations and regions illustrated by an extensive range of research and development in technology. Regarding maritime applications, researchers have recognized the utilization of hydrogen as a fuel for fuel cells, a device that converts the chemical energy of the fuel to electrical energy. Solid oxide fuel cell (SOFC), with high working temperature, is easy to combine with the waste heat recovery cycles/devices to increase output power and thermodynamic performances as well. Furthermore, the cold energy from liquid hydrogen supplied to SOFC can also be used to generate more power. In this study, we proposed a SOFC integrated system with the idea of combining the waste heat recovery from the SOFC exhaust stream and cold energy utilization from LH₂. The designation is aimed to target small-scale vessel which uses electric propulsion for short distances voyage.

• Journal of Korea Port Economic Association
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• v.39 no.4
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• pp.255-268
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• 2023

This paper focuses on the tests for generalized fluctuation in the context of assessing structural changes based on linear regression models. For efficient estimation there has been a growing focus on the structural change monitoring, particularly in relation to fields such as artificial intelligence(hereafter AI) and machine learning(hereafter ML). Specifically, the investigation elucidates the implementation of structural changes and presents a coherent approach for the practical application to the BDI(Baltic Dry-bulk Index), which serves as a representative maritime trade index in global market. The framework encompasses a range of F-statistics type methodologies for fitting, visualization, and evaluation of empirical fluctuation processes, including CUSUM, MOSUM, and estimates-based processes. Additionally, it provides functionality for the computation and evaluation of sequences of pruned exact linear time(hereafter PELT).

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.969-976
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• 2004

Cassava peelings waste, which is both a waste and pollutant, was chemically modified using mercaptoacetic acid (MAA) and used to adsorb $Cu^{2+}\;and\;Cd^{2+}$ from aqueous solution over a wide range of reaction conditions at $30^{\circ}C$. Acid modification produced a larger surface area, which significantly enhanced the metal ion binding capacity of the biomass. An adsorption model based on the $Cu^{2+}/Cd^{2+}$ adsorption differences was developed to predict the competition of the two metal ions towards binding sites for a mixed metal ion system. The phytosorption process was examined in terms of Langmuir, Freundlich and Dubinin-Radushkevich models. The models indicate that the cassava waste biomass had a greater phytosorption capacity, higher affinity and greater sorption intensity for $Cu^{2+}\;than\;Cd^{2+}$. According to the evaluation using Langmuir equation, the monolayer binding capacity obtained was 127.3 mg/g $Cu^{2+}$ and 119.6 mg/g $Cd^{2+}$. The kinetic studies showed that the phytosorption rates could be described better by a pseudo-second order process and the rate coefficients was determined to be $2.04{\times}10^{-3}\;min^{-1}\;and\;1.98{\times}10^{-3}\;min^{-1}\;for\;Cu^{2+}\;and\;Cd^{2+}$ respectively. The results from these studies indicated that acid treated cassava waste biomass could be an efficient sorbent for the removal of toxic and valuable metals from industrial effluents.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.2
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• pp.172-182
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• 2020

In order to offer specific information needed to assist in operation of a ship with same type rudder through evaluating the maneuverability of training ship A-Ra with flapped rudder, sea trials based full scale for turning test, zig-zag test with rudder angle 10° and 20°, and spiral test at service condition were carried out on starboard and port sides around Jeju Island according to the standards of maneuverability of IMO. As a result, the angular velocity of port turn was higher than that of starboard turn. Therefore, the size of turning circle was longer on the starboard side. In addition, variation of the transfer due to various factors was more stable than those of the others. In the Z-test results, the mean of 1st and 2nd overshoot angles were 9.8°, 6.3° and 15.3°, 9.2° respectively when the port and starboard was 10°; the 1st overshoot angle were 18°, 13.7° when using 20°. Her maneuverability index T' and K' can be easily determined by using a computer with the data obtained from Z-test where K' and T' are dimensionless constants representing turning ability and responsiveness to the helm, respectively. In the Z-test under flap rudder angle 10°, the obtained K' value covered the range of 2.37-2.87 and T' was 1.74-3.45. Under the flap rudder angle 20°, K' and T' value showed 1.43-1.63, 1.0-1.73, respectively. In the spiral test, the loop width was unstable at +0.3° and -0.5°-0.9° around the midship of flap rudder. As a result, course stability was comparatively good. From the sea trial results, training ship ARA met the present criterion in the standards of maneuverability of IMO.

• Journal of Navigation and Port Research
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• v.34 no.1
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• pp.45-50
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• 2010

After September 11 attacks, as recently the range about security of physical distribution is rapidly spreading temporally & spatially, and it considers that the demand of understanding about logistics company is more than that of the past, now is the time that to establish policy for a comprehensive and systematic support policy that targets the entire supply chain considering the competitive of logistics beyond the responsibility for security of the field of import and export simply. In this respect, this study has identified recognition of domestic logistics company about global logistics security system that has recently been implemented in the country, and this level of recognition has really examined what is the impact of its logistics competitiveness and an intention to invest in related areas in the future. Based on this, this study has also proposed the supporting promotion and education for the expansion of logistics security of government & related agencies and effective way promoting to establish policies regarding this.

• Journal of Veterinary Clinics
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• v.39 no.6
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• pp.319-325
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• 2022

Two-port laparoscopic ovariectomy (Lap-OVE) has been performed in small dogs, using 3-mm and 5-mm portal sites, and is associated with reduced surgical stress and postoperative pain. However, extension of the incision is often needed to extract the ovaries. In this study, we aimed to minimize invasiveness by using smaller-sized cannulas as well as a novel technique for ovary extraction. Lap-OVE was performed on six, healthy female dogs (range, 3 to 7.2 kg) using two 3-mm midline portals. The middle finger of a size M nitrile glove was cut at its base and sterilized preoperatively. The ovary was suspended at the body wall using a 1-0 blue nylon needle, and the ovarian pedicle and ligaments were transected using a 3-mm bipolar forceps. To facilitate the glove passing through the 3.9-mm port, it was turned inside out to expose the smooth inner surface, before being inserted into the abdominal cavity with an applicator. Both ovaries were placed inside, and the mouth of the glove was exteriorized through the port with a laparoscopic grasping forceps. The ovaries were morcellated inside the glove, using Adison-Brown tissue forceps and iris scissors, which enabled safe extraction without incision enlargement. Median incision lengths were 4.3 mm (3.5-mm cranial cannula) and 4.8 mm (3.9-mm caudal cannula). An advantage of this procedure was that there was no need for skin sutures. In conclusion, using our novel technique, sutureless Lap-OVE was possible in small dogs using two 3-mm portal sites without additional incision.

• Journal of the Economic Geographical Society of Korea
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• v.14 no.3
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• pp.407-418
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• 2011

The southern region including Guangzhou(黃州), the capital of Guangdong Province, was called "South of the Mountain Range" (嶺南) because it is located south of the Five Mountain Ranges (五嶺) which made mobility difficult prior to unification of China by Qin dynasty (秦) in 221 BCE. The Guangdong region of the South of the Mountain Range (嶺南) was an administratively independent unit and, as such, called the Nanyue kingdom (南越國). This is the origin of the Chinese character "yue", and terms such as yueyu (Cantonese), yuecai (Cantonese cuisine), yueju (Cantonese opera) are still in use today. Guangzhou, called Panyu (番禹) during the Nanyue kingdom period, was settled early in the northern part of the Pearl River (珠江, Zhu Jiang) delta. It became the first port to open its doors to the great powers of the West during the Qing period. Although it has now fallen behind Shanghai which developed later, Guangzhou is still the third largest city after Beijing and Shanghai, and thus, it is an influential open coastal city. Today, not only is Guangzhou the world center of the light textile industry, it also spurs development in various manufacturing industries. Along with nearby Hong Kong, Macao, and Shenzhen, it plays the role of cradle of the Pearl River delta economic zone. Firmly established early on as the greatest central city in southern China, Guangzhou is simultaneously a hub in various aspects such as regional politics, economics, and culture; it was also the center of revolution and resistance which attempted to challenge the northern political powers. Guangzhou is known for the history of the rise and fall of its port, but with developmental efforts, it still maintains its influence. Guangzhou's dynamic development of today brings with it issues such as the environment and moral system which must be dealt with.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2006.05a
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• pp.95-108
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• 2006

Because of rapid expansion of third party logistics, fierce competition in the transportation industry, and the diversification and globalization of transportation channels, an effective transportation planning by means of multimodal transport is badly needed. Accordingly, this study aims to suggest an optimal transport algorithm for the multimodal transport in the international logistics. Cargoes and stopovers can be changed numerously according to the change of transportation modes, thus being a NP-hard problem. As a solution for this problem, first of all, we have applied a pruning algorithm to simplify it, suggesting a heuristic algorithm for constrained shortest path problem to find out a feasible area with an effective time range and effective cost range, which has been applied to the Label Setting Algorithm, consequently leading to multiple Pareto optimal solutions. Also, in order to test the efficiency of the algorithm for constrained shortest path problem, this paper has applied it to the actual transportation path from Busan port of Korea to Rotterdam port of Netherlands.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.865-875
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• 2022

Field measurements and numerical simulations using EFDC model were performed to quantify the changes of water circulation near Gusipo coast located in the Yellow Sea of Korea to estimate the impact of the construction of the coastal structures (jetty, groin, Gusipo port and bridge). The model predicted tide and tidal currents agreed reasonably well with the measurements. The maximum currents during spring tide near the Gusipo Beach (GB) have the range of 20~40 cm/sec whereas those off the GB range from 60 to 80 cm/sec. The typical patterns of tidal current show parallel with the local isobath. Tidal currents flow northeastward during the flood tide whereas the currents during the ebb tide flow southwestward. The current speeds at shielded waters after the construction of coastal structures strongly decreased as compared with those before the construction. The tidal volume due to the construction of coastal structures was estimated using the depth averaged velocity for 24 hours of spring tide. Tidal volume after construction of coastal structures was compared with initial state (before construction). Tidal volume at present state (after construction of jetty, groin, Gusipo port and bridge) decreased by 28.4% as compared with that of the initial state. The volume after construction of jetty and groin decreased by 21.3%, and the volume after construction of Gusipo port and bridge decreased by 9.8%.