• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.177-183
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• 2007

Flow characteristics of the cylinder wake controlled with a small control cylinder were experimentally investigated by the PN (Particle Image Velocimetry) technique. Flow visualization of the flow around a circular cylinder was conducted in the Circulating Water Channel. The control cylinder having diameter of d=5mm, 10mm and 20mm was installed behind a circular cylinder of D=50mm. And the Reynolds number were $Re=4.9{\times}10^3,\;Re=9.9{times}10^3$ and $Re=1.9{\times}10^4$. In this study, the frequency characteristics of the controlled wake were analyzed by using spectral analysis of the measured wake velocity signals. As a result, the controlled wake had smaller vortex shedding frequency than that of circular cylinder wake by the effect of the control cylinder. Governing parameters of the flow control were d/D, and Reynolds number and they largely influenced the frequency characteristics of the cylinder wake. And vortex shedding frequency appeared most lowly at d=0.2D

• Journal of Industrial Convergence
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• v.20 no.8
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• pp.163-172
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• 2022

Public officials are volunteers for the people, and the police are in charge of the safety of the people. In particular, the marine safety of Korea, which has three sides of the sea, is very important. The education of maritime police is a very important factor due to the specificity and risk of the sea. In particular, since the new curriculum is linked to the job while in office, factors related to educational performance are more important. In this study, the relationship between personality characteristics and academic burnout was examined for 200 new maritime police officials. Among the five factors of personality characteristics, extroversion factors, neurotic factors, and emotional exhaustion factors were extroversion factors, neurotic factors, and cynicism factors, and extroversion factors, neurotic factors, and integrity factors. In particular, the five factors of personality characteristics that have the greatest influence on academic burnout were neurotic. For the educational satisfaction and effectiveness of the new maritime police officer, it is necessary to minimize the psychological margin and stress of the new maritime police officer.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.29-33
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• 2009

This study devised and tested a histological staging system for gonadal development in the trumpet shell, Charonia sauliae, which was collected along the south coast of Jeju Island, South Korea. This paper details for the first time the gonadal development characteristics of C. sauliae. Ovary and testis development in C. sauliae can be roughly divided into five stages: growing, mature, spent, degenerative, and resting. The trumpet shelll has multiple fecundation and fertilization during the spawning season for out-of-step gonadal development in high-temperature and low-salinity environments. Female trumpet shell tended to have larger shells and were more abundant than males (64.26% of all animals collected were female).

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.974-980
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• 2014

Aluminum acts as sacrificial anode and corrosion protection with Al2O3 formation. If the same current on material for Al ships with steel ships supplies, the more hydrogen would be occurred, that result is bring about over-protection. For this reason, the damage by hydrogen embrittlement leads to the serious accident. In this study, we evaluate electrochemical behavior with rotation speed of 5083-H116 Al alloy material for Al ship in seawater. To examine the electrochemical characteristics with rotation speed and its effects on performance, experiments were conducted at four rotation speed. Results of experiments, the corrosion current density and damage were increased by applying the rotation speed compared to static state.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.8
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• pp.924-931
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• 2007

Now, there are two big issues threatening global society, which are the depletion of fossil fuels and the environmental disruption. Therefore, marine diesel engine, taking up over 95% share of the marine power market, has met the environmental and economical problems, too. These problems have caused a necessity of new, alternative power systems in ships and fuel cell systems has been playing a central role as one of the alternatives. This paper analyzes the characteristics of marine fuel cell systems, R&D trends of advanced countries, and mapping out R&D strategy of Korea.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.177-181
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• 2005

Fishing selectivity is determined by the level of voluntary escaping behavior in accordance with decision-making based on the relationship between fish size and mesh size. This study examined movement during the swimming behavior of black porgy in a trawl's towing cod-end and analyzed the movement components such as swimming speed, angular velocity of turning, and distance to the net over time. Most of the observed fish exhibited an optomotor response, maintaining position and swimming speed without changing direction. Others exhibited erratic or 'panic' behavior with sudden changes in swimming speed and direction. The latter behavior involved very irregular and aperiodic variations in swimming speed and angular velocity, termed 'chaotic behavior.' Thus, the results of this study can be applied to a chaotic behavior model as a time series of swimming movements in the towing cod-end for the fishing selectivity.

• Journal of Navigation and Port Research
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• v.31 no.7
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• pp.623-628
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• 2007

By employing primarily the Kendall's Concordance Test, the paper attempted to conduct an experts' evaluation on the interaction among the agents in Busan marine tourism cluster and recommend some measures for policy consideration for the cluster's activation. For this purpose, a conceptual framework was developed to guide the assessment by using inter-agent cooperation and network approaches regarding the nature of the marine tourism cluster. Such factors as cooperation, competition, relationship marketing, and networking were identified as critical. Findings of the study imply that Busan marine tourism cluster is at its embryonic stage and needs desperate measures for improvement in the inter-organizational cooperation and networking, the major regional characteristics that determine the competitiveness of marine tourism.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.74-85
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• 2022

Organisms constituting a large proportion of marine ecosystems, ranging from bacteria to fish, exhibit fluorescence and bioluminescence. A variety of marine organisms utilize these biochemically generated light sources for feeding, reproduction, communication, and defense. Since the discovery of green fluorescent protein and the luciferin-luciferase system more than a century ago, numerous studies have been conducted to characterize their function and regulatory mechanism. The unique properties of fluorescent and bioluminescent proteins offer great potential for their use in a broad range of applications. This short review briefly describes the functions and characteristics of fluorescent and bioluminescent proteins, in addition to summarizing the recent status of their applications.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.4
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• pp.516-528
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• 2010

The Korean marine equipment industry is, in significant ways, behind the shipbuilding industry. For example, in terms of the number of orders received, the shipbuilding industry has ranked first in the world since 2003. In contrast, the global competitiveness of Korea's marine equipment industry is still relatively weak. This is important not only for the equipment industry, but because these two industries have many links. The structure of this research was firstly, to identify theoretical issues by looking at the characteristics of the marine equipment companies, marketing recognition, uses of marketing, and financial outcomes. Second, the study developed an analytical framework for empirical examination using configuration of each factor. Third, each factor has been analysed empirically. Forth, this study presents the importance of marketing for marine equipment companies within Korea, as well as in a global market. Finally, the study suggests a new marketing strategy for Korea's marine equipment companies to achieve global competitiveness.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.659-673
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• 2021

This study aims to investigate the impact of the High Pressure Selective Catalytic Reduction system (SCR-HP) on a large marine two-stroke engine performance parameters by employing thermodynamic modelling. A coupled model of the zero-dimensional type is extended to incorporate the modelling of the SCR-HP components and the Control Bypass Valve (CBV) block. This model is employed to simulate several scenarios representing the engine operation at both healthy and degraded conditions considering the compressor fouling and the SCR reactor clogging. The derived results are analysed to quantify the impact of the SCR-HP on the investigated engine performance. The SCR system pressure drop and the cylinder bypass valve flow cause an increase of the engine Specific Fuel Oil Consumption (SFOC) in the range 0.3-2.77 g/kWh. The thermal inertia of the SCR-HP is mainly attributed to the SCR reactor, which causes a delayed turbocharger response. These effects are more pronounced at low engine loads. This study supports the better understanding of the operating characteristics of marine two-stroke diesel engines equipped with the SCR-HP and quantification of the impact of the components degradation on the engine performance.