• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.99-104
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• 2022

This study was to analyze the effects of sudden rise in cortisol and human symptoms in the situation of rescue at river, The experimental results are as follows. The subjects were A, B, C, and the values of cortisol elevation before and after diving were 6.30ug/dl, 6.50ug/dl, and 6.57ug/dl, respectively. However, in the subject D, the elevation of cortisol before and after diving was significantly elevated to 11.00ug/dl. The reason for this is thought to be the depletion of physical strength through weighty due to the inferiority of the underwater view and tense during the sudden rise. The subjects E showed significantly lower cortisol elevation before and after diving, as 4.28ug/dl, because the age of E was the youngest of the subjects and the anxiety was low due to abundant experience of deep sea diving. Fatigue is 7 to 8, anxiety is 7 to 9, Both showed high values. Psychological strain increased fatigue in underwater search, and poor visual field seemed to increase anxiety. The research results will be provided as empirical data on the safe underwater search activities of rescuers.

• Journal of Ocean Engineering and Technology
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• v.36 no.5
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• pp.340-352
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• 2022

This article presents a modeling method for the uncorrelated measurement error of the ultra-short baseline (USBL) acoustic positioning system for aiding navigation of underwater vehicles. The Mahalanobis distance (MD) and principal component analysis are applied to decorrelate the errors of USBL measurements, which are correlated in the x- and y-directions and vary according to the relative direction and distance between a reference station and the underwater vehicles. The proposed method can decouple the radial-direction error and angular direction error from each USBL measurement, where the former and latter are independent and dependent, respectively, of the distance between the reference station and the vehicle. With the decorrelation of the USBL errors along the trajectory of the vehicles in every time step, the proposed method can reduce the threshold of the outlier decision level. To demonstrate the effectiveness of the proposed method, simulation studies were performed with motion data obtained from a field experiment involving an autonomous underwater vehicle and USBL signals generated numerically by matching the specifications of a specific USBL with the data of a global positioning system. The simulations indicated that the navigation system is more robust in rejecting outliers of the USBL measurements than conventional ones. In addition, it was shown that the erroneous estimation of the navigation system after a long USBL blackout can converge to the true states using the MD of the USBL measurements. The navigation systems using the uncorrelated error model of the USBL, therefore, can effectively eliminate USBL outliers without loss of uncontaminated signals.

• Ocean and Polar Research
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• v.45 no.2
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• pp.71-87
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• 2023

Climate change causes ocean warming, ocean acidification, sea-level rise, dynamic coastal risk, change of ecosystem structure and function, and degradation of ecosystem services. Not only that, but it has negatively impacted the well-being of people, society, and culture, including food security, water resources, water quality, livelihood, health, welfare, infrastructure, transport, tourism, recreation, and so on, especially by particularly degrading indigenous communities and generating an inequitable distribution of benefits and costs. As pointed out here, these adverse impacts of climate change on the ocean have been emphasized at the international and national levels. In contrast, the ocean field has been neglected in the climate change conversation for too long. However, since the UNFCCC COP 25, the ocean has been drawn into the discussion as a solution to address climate change. Moreover, the U.S. Congress recently unveiled a bill called the 'Ocean-Based Climate Solution Act, OBCSA' that reflects the new paradigm of the international regime. The comprehensive legislative bill includes elements related to climate inequity, a blue economy, and a community-led bottom-up policy mechanism, which will have a significant bearing on the ocean-climate legal system. Therefore, this study reviews the OBCSA and deduces implications with regard to the ocean-climate legal system in Korea.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.106-112
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• 2022

As a series of basic research to draw the pilot design measures for developing the habitat apparatus of Sulculus diversicolor supertexta inhabiting the coastal area of Jeju island, this study conducted a water tank experiment to understand the habitat marine environment of Sulculus diversicolor supertexta and the preference of habitat space focusing on the research fisheries performing the discharge of marine products. In the composition degree of marine algae in both fisheries, Donggwi-ri showed the highest gulfweed (79.3%) as brown algae and there were some coralline algae (17.2%) as red algae. Hansu-ri yielded the highest gulfweed (48.1%) as brown algae, which was followed by sea lettuce (10.4%) as green algae. In the preference of habitat space, the shelter angles 40° showed the highest adhesion as number of 82.9, which was followed by 60° and 70° as 69.2 and 68.2 respectively (P<0.05) by reviewing the environmental characteristics of habit of Salculus diversicolor supertexta in the coastal fishery of Jeju Island, when considering the adhesion rate in each of five shelters with different angles. In the future, there should be continuous research and monitoring for designing the fish shelters suitable for the coastal fisheries of Jeju island, and it would be also necessary to add the field-centered sustainable concrete research.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.4
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• pp.132-159
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• 2020

As multidisciplinary marine research is actively conducted, various types of marine research facilities and equipment are purchased every year. However, among marine research facilities and equipment, it is difficult to classify and manage various types of field observation equipment used for environmental data collection and sample collection under the current national research facility and equipment standard classification system. In the case of Korea Institute of Ocean Science and Technology, about 30% of research facilities and equipment are unclassified and not properly managed. In this study, marine research facilities and equipment are classified into 7 middle and 36 sub-classes according to their characteristics. It is proposed to add a large classification group called 'Environmental Observation/Analysis Equipment', to the national research facility equipment standard classification system. In addition, it is proposed to classify the equipment operated in the laboratory among marine research facilities and equipment according to the existing national research facility equipment standard classification system. Through this, it is expected that all of Korea's marine-related research facilities and equipment can be systematically classified and managed effectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.157-157
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• 2022

Recent decades have seen all over the world increasing drought in some regions and increasing flood in others. Climate change has been alarming in many regions resulting in degradation and diminution of available freshwater. The effect of global warming and overpopulation associated with increasing irrigated farming and valuable agricultural lands could be particularly disastrous for coastal areas like the one of Benin. The coastal region of Benin is under a heavy demographic pressure and was in the last decades the object of important urban developments. The present study aims to roughly study the general effect of climate change (Sea Level Rise: SLR) and groundwater pumping on Seawater intrusion (SWI) in Benin's coastal region. To reach the main goal of our study, the region aquifer system was built in numerical model using SEAWAT engine from Visual MODFLOW. The model is built and calibrated from 2016 to 2020 in SEAWAT, and using WinPEST the model parameters were optimized for a better performance. The optimized parameters are used for seawater intrusion intensity evaluation in the coastal region of Benin The simulation of the hydraulic head in the calibration period, showed groundwater head drawdown across the area with an average of 1.92m which is observed on the field by groundwater level depletion in hand dug wells mainly in the south of the study area. SWI area increased with a difference of 2.59km² between the start and end time of the modeling period. By considering SLR due to global warming, the model was stimulated to predict SWI area in 2050. IPCC scenario IS92a simulated SLR in the coastal region of Benin and the average rise is estimated at 20cm by 2050. Using the average rise, the model is run for SWI area estimation in 2050. SWI area in 2050 increased by an average of 10.34% (21.04 km²); this is expected to keep increasing as population grows and SLR.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.97-126
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• 2011

This paper has identified the Quaternary Environmental research trend of the Korea that has become the center of physical geographers and analyzed its performance by topic. As a result, we could see that most studies are accepted as research topics of restoring topography-climate-vegetation-sea level-soil environment during 'Last Interglacial ~Holocene' targeting the Korean Peninsula and the surrounded area. However, the situation is that it is difficult to restore the Quaternary Environment of the Korea in general only with their study performance. In the future, I hope the Quaternary Environmental research of the Korea would play more leading role than the researchers of other field by selecting more wide ranged and in-depth study topics in terms of the Quaternary Environmental research to furthermore introduce a new analytic technique.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.89-90
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• 2021

Undersea bases built in the deep sea are built in more extreme environments than in space. In addition, it requires the convergence of mechanics, electronics, shipbuilding, meteorology, and diving science, marine physics, chemistry, biology, and geology. Undersea base can be constructed through the fusion of various technologies. The development of extreme technology for undersea construction will be the most advanced technology in each field, and it will be applied to space and other fields, so it will be an opportunity to preempt the latest technology.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.1
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• pp.43-49
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• 2007

The methods of physical oceanographic surveys to examine the effect of thermal discharge from nuclear power plants in Korea have been reviewed and a standard guide to the survey is proposed. It is desirable that in situ observation and numerical thermal diffusion modeling are conducted simultaneously to describe the variation in temperature distribution affected by thermal discharge from a power plant because any observation or numerical modeling alone has limits to do so quantitatively. It is suggested that the field observation must be based on the concept of heat budget modeling considering all artificial and natural heat sources/sinks around the power plant. Any results from numerical modeling must reach to a certain statistical significance level to use for a standard temperature distribution. In addition, the development of standard numerical codes is proposed to improve the problems shown in the past numerical circulation and diffusion modelling.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.63-68
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• 2009

Among various microscopic organisms producing photobiological hydrogen, cyanobacteria have long been recognized as the promising biological agents for hydrogen economy in 21 century. For photobiological production of hydrogen energy, marine unicellular $N_2$-fixing cyanobacteria have been evaluated as an ideal subgroup of Cyanophyceae. To develope the hydrogen production technology using unicellular $N_2$-fixing cyanobacteria, 3 important factors are pre-requisite: 1) isolation of the best strain from marine natural environment, 2) exploration on the strain-specific optimal conditions for the photobiological hydrogen production, and finally 3) application of the molecular genetic tools to improve the natural ability of the strain to produce hydrogen. Here we reviewed the recent research & development to commercialize photobiological hydrogen production technology, and suggest that intensive R&D during next 10-15 years should be imperative for the future Korean initiatives in the field of the photobiological hydrogen production technology using photosynthetic marine unicellular cyanobacterial strains.