• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.363-372
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• 2023

This study was developed to prepare hamburger steak (HS), wantang soup (WS), and tomato soup (TS) for senior-friendly seafood's (SFS) using bigeye tuna Thunnus obesus, and to investigate their quality characteristics. All data were presented in the order of HS, WS, and TS. The hardness values were 298.9×1.0³, 47.1×1.0³ and 14.9 ×1.0³ N/m², respectively. The viscosity of TS was 2,856 mPa·s. The protein contents were 13.8, 11.7, and 9.7 g/100 g, respectively. The fat-soluble vitamins content were as follows: vitamin A 21.88, 5.03, and 23.72 ㎍RAE/100 g; vitamin D 1.15, ND, and 1.81 ㎍/100 g, respectively. The water soluble vitamins contents were as follows: vitamin C 47.22, 32.83 and 37.01 mg/100 g; vitamin B₂ 0.17, 0.11 and 0.10 mg/100 g; vitamin B₃ 34.87, 34.76 and 54.62 mgNE/100 g. The Ca contents were 15.9, 16.8, 28.9 mg/100 g, and the K contents were 383.8, 167.4, and 300.0 mg/100 g, respectively. The dietary fiber was 0.04, 0.07 and 0.08 g/100 g, respectively. Escherichia coli was not detected in any of the products. These results suggest that the products should be classified as follows, based on their appropriateness as SFS: HS, WS and TS.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.348-357
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• 2019

To investigate the changes of dominant species of benthic macroinvertebrates following summer precipitation variance, we surveyed twenty five sites of the main Seomjin River in May and September in 2014 and 2015. The temperature, precipitation, water quality factors and substrate composition, water depth and flow velocity, which are important factors in benthos habitat environment, were collected and measured. There is not much difference of the cumulative precipitation (CP) between 2014 (2,322.1 mm) and 2015 (2,371.0 mm) in May. However CP in september was decreased by more than half in 2015 (3,726.1 mm) than 2014 (7,678.2 mm). Due to washing effect by summer precipitation, total number of species and individuals for benthic macroinvertebrates were higher in May than in September. Chironomidae spp. and Choroterpes altioculus were dominated in May, Ecdyonurus levis, Ecdyonurus kibunensis were dominated in September. As a result of correlation analysis between community indices and environment factors, it was found that there is a significant correlation with flow velocity and substrate compositions. According to the results of cluster analysis and PCA based on environment fators and dominant species of benthic macroinvertebrates in Seomjin River, it was divided into four groups following CP and MT. Ecdyonurus levis and Ecdyonurus kibunensis reflect the effect of the decrease in summer precipitation.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1485-1491
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• 2015

There are two treatment processes that are currently applied to ships are the biological treatment process using the activated sludge and the electrochemical treatment. However, neither of them are able to remove both nitrogen and phosphorus due to their limited ability to remove organic matters, which are main causes of the red tide. This study was conducted to identify the characteristics of nitrogen removal factors from manure wastewater by replacing the final settling tank in SBR (Sequencing Batch Reactor) process and applying immersion type hollow fiber membrane. SBR process is known to have an advantage of the least land requirement in special environment such as in ship and the immersion type hollow fiber membrane is more stable in water quality change. As the result, the average in the cases of DO (Dissolved Oxygen) is 2.9(0. 6~3.9) mg/L which was determined to be the denitrifying microorganism activity in anaerobic conditions. The average in the cases of ORP (Oxidation Reduction Potential) is 98.4~237.3 mV which was determined to be the termination of nitrification since the inflection point was formed on the ORP curve due to decrease in the stirring treatment after the aeration, same as in the cases of DO. Little or no variation in the pH was determined to have positive effect on the nitrification. T-N (Total Nitrigen) removal efficiencies of the finally treated water were 71.4%, 72.3% and 66.5% in relatively average figures, thus was not a distinct prominence. In being applied in ships in the future, the operating conditions and structure improvements are deemed necessary since the MEPC (Marine Environment Protection Committee). 227(64) ship sewage nitrogen is less than the standard of 20 Qi/Qe mg/L or the removal rate of 70%.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.56-67
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• 1999

It is desired to use a domestically manufactured ocean data buoy for the long-term operational ocean monitoring. The ocean data buoy manufacturing technology was introduced through the research cooperation with the Qingkong University of Taiwan. The introduced ocean data buoy system was further expanded and improved for more efficient application for the marine environmental monitoring in Korea. The size of the ocean data buoy is 2.5 m in diameter, which is smaller compared to the NOAA's 3.0 m discus buoy to allow easy land transportation and ocean deployment as well. From the dynamic response test of the buoy carried out numerically, it was shown that the measurement of waves with period greater than 4 seconds is acceptable. The measurement and control system of the data buoy were improved to increase the number of measuring parameters, to reduce power consumption and to enhance better data analysis and management. Each component of the improved data buoy system was described in detail in this paper. Water quality sensors of water temperature, salinity, DO, pH and turbidity were added to the system in addition to the marine meteorological sensors of wind speed and direction, air temperature, humidity, air pressure and wave. Inmarsat satellite communication system is used for the real-time data telemetry from the buoy deployed offshore. A field performance test of the improved and domestically manufactured buoy was carried out for a month at the open sea off Pohang together with DatawelI's Wave-rider buoy to compare the wave data. The results of the test were satisfactory.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.158-165
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• 2010

Phytoplankton community structure is one of the indicators that can explain the enviromnental characteristics of coastal waters. In this study, phytoplankton community structure and water quality of aquaculture area were investigated for understanding regional enviromnental characteristics. Thirty stations in aquaculture areas of Tongyeong, southeast coast of Korea, were investigated monthly from January to December, 2009. Phytoplankton community, meteorologic dada and enviromnent factors including temperature, salinity, transparency, nutrients and chlorophyll a were also examined. Chaetoceros spp. and unidentified small flagellates were dominant species in all the year round. Pseudo-nitzschia spp., Dictyocha spp., and Nitzschia longissima were dominant in June to October being summer season, and Skeletonema costatum, Thalassiosira spp., Eucamphia zodiacus, Akashiwo sanguinea, Gymnodinium spp. and Asterionella japonicus appeared as dominant species in the rest of months. Dinoflagellate blooms occurred 3 times in near Hansan Bay and around Saryang-do, and the highest chlorophyll a was found in Hansan Bay. Species diversity of phytoplankton was lower in Hansan and Womnum Bay, and diatom was more abundant than dinoflagellates in Mireuk-do waters. These results showed that phytoplankton community varied by the seasonal and geographical characteristics, and recent increase of water temperature and heavy rain may affect on phytoplankton community structure.

• Atmosphere
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• v.28 no.1
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• pp.99-112
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• 2018

In this study, the accuracy of ocean analysis data, which are produced from the Korea Meteorological Administration (KMA) Nucleus for European Modelling of the Ocean/Variational Data Assimilation (NEMO/NEMOVAR, hereafter NEMO) system and the HYbrid Coordinate Ocean Model/Navy Coupled Ocean Data Assimilation (HYCOM/NCODA, hereafter HYCOM) system, was evaluated using various oceanic observation data from March 2015 to February 2016. The evaluation was made for oceanic thermal environments in the tropical Pacific, the western North Pacific, and the Korean peninsula. NEMO generally outperformed HYCOM in the three regions. Particularly, in the tropical Pacific, the RMSEs (Root Mean Square Errors) of NEMO for both the sea surface temperature and vertical water temperature profile were about 50% smaller than those of HYCOM. In the western North Pacific, in which the observational data were not used for data assimilation, the RMSE of NEMO profiles up to 1000 m ($0.49^{\circ}C$) was much lower than that of HYCOM ($0.73^{\circ}C$). Around the Korean peninsula, the difference in RMSE between the two models was small (NEMO, $0.61^{\circ}C$; HYCOM, $0.72^{\circ}C$), in which their errors show relatively big in the winter and small in the summer. The differences reported here in the accuracy between NEMO and HYCOM for the thermal environments may be attributed to horizontal and vertical resolutions of the models, vertical coordinate and mixing scheme, data quality control system, data used for data assimilation, and atmosphere forcing. The present results can be used as a basic data to evaluate the accuracy of NEMO, before it becomes the operational model of the KMA providing real-time ocean analysis and prediction data.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.41-48
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• 2009

Natural magnetic fields are attenuated by electrically conductive water. For that reason, marine magnetotelluric surveys have collected data at long periods (1000-100 000 s). The mantle structure has been the main target of seafloor magnetotelluric measurements. To ascertain crustal structure, however, electromagnetic data at shorter periods are important, e.g. in investigations of megathrust earthquake zones, or in natural resource surveys. To investigate of the former, for example, electromagnetic data for periods of less than 1000 s are necessary. Because no suitable ocean bottom electromagnetometer (OBEM) has been available, we have developed a small OBEM and ocean bottom electrometer (OBE) system with a high sample rate, which has an arm-folding mechanism to facilitate assembly and recovering operations. For magnetic observation, we used a fluxgate sensor. Field observations were undertaken to evaluate the field performance of our instruments. All instruments were recovered and their electromagnetic data were obtained. Results of the first experiment show that our system functioned well throughout operations and observations. Results of other field experiments off Tottori support the claim that the electromagnetic data obtained using the new OBEM and OBE system are of sufficient quality for the survey target. These results suggest that this device removes all instrumental obstacles to measurement of electromagnetic fields on the seafloor.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.88-99
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• 2021

In this study, a land-based marine closed mesocosm (LMCM) experiment was performed to objectively assess the initial stability of an artificial ecosystem experiment against biological and non-biological factors when evaluating ecosystem risk assessment. Changes in the CV (coefficient of value) amplitude were used as data to analyze the stability of the experimental system. The CV of the experimental variables in the LMCM groups (200, 400, 600, and 1,000 L) was maintained within the range of 20-30% for the abiotic variables in this study. However, the difference in CV amplitude in biological factors such as chlorophyll-a, phytoplankton, and zooplankton was high in the 600 L and 1,000 L LMCM groups. This result was interpreted as occurring due to the lack of control over biological variables at the beginning of the experiment. In addition, according to the ANOVA results, significant differences were found in biological contents such as COD (chemical oxygen demand), chlorophyll-a, phosphate, and zooplankton in the CV values between the LMCM groups(p<0.05). In this study, the stabilization of biological variables was necessary to to control and maintain the rate of changes in initial biological variables except for controllable water quality and nutrients. However, given the complexity of the eco-physiological activities of large-scale LMCMs and organisms in the experimental group, it was difficult to do. In conclusion, artificial ecosystem experiments as a scientific tool can distinguish biological and non-biological factors and compare and analyze clear endpoints. Therefore, it is deemed necessary to establish research objectives, select content that can maintain stability, and introduce standardized analysis techniques that can objectively interpret the experimental results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.43-57
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• 2024

As coastal areas have a distinct nature with the interaction of the lands and waters, they attract people to enjoy and experience the natural environments physically and intellectually; this generates cultural ecosystem services. Coastal beaches are one of the most common coastal areas for cultural ecosystem services. The purpose of this study was to 1) estimate the economic values of cultural ecosystem services derived from coastal beaches, and 2) expand the estimated values into other beaches across the country using a benefit transfer method. We divided the values of cultural ecosystem services into five different categories based on an extensive literature review: recreation and tourism, landscape and aesthetic, educational, heritage, and inspirational values. The values of tourism and recreation, landscape and aesthetic, and educational services were estimated using the choice experiments. The attributes of the choice experiments consisted of conservation funds, litter, water quality, seascape, landscape, and biodiversity, and the data were collected through online surveys with visitors of 11 representative beaches in Korea. Heritage and inspiration services were estimated using a market goods method based on their expenditures. These values were transferred to 257 beaches across the country. Study results can be used for policy decisions on various restoration and conservation projects caused by coastal erosion and development and on the need and extent of public investments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.463-470
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• 1998

To improve muscle quality and prolong freshness of sashimi, the effects of freezing-thawing condition on physicochemical and rheological properties of plaice muscle were investigated. Muscle tested were frozen with quick freezing (liquid nitrogen gas) or slow freezing ($-15^{\circ}C$ air). Transition time of zone of ice crystal formation was within 10 minute for quick freezing and 110 minute for slow freezing. Time required for thawing to $0^{\circ}C$ in muscle temperature by various thawing methods was shortest with $25^{\circ}C$ tap water, followed by $15^{\circ}C$ tap water, $10^{\circ}C$ tap water, $25^{\circ}C$ air, $5^{\circ}C$ tap water and $0^{\circ}C$ cold water. Breaking strength of muscle was higher in quickly frozen sample than in slowly frozen sample. According to sashimi term, changes in breaking strength of muscle did not show any difference in quickly frozen sample, while showed significant difference in slowly frozen sample. The remaining content of ATP was not effected by freezing speed, and ATP content was apt to higher in quickly thawed sample than in slowly thawed sample. IMP was the majority of ATP and it's related compounds of sample after freezing and thawing. Collagen matrix was weakened markedly in slowly frozen sample than in quickly frozen sample.