• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.19-29
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• 2022

The result of a questionnaire survey conducted on fishermen using coastal fish traps shows that fall accidents during trap dropping and pulling constitute the highest proportion of accidents at 42.1 %, whereas slipping accidents on the deck or stricture accidents to the body due to the trap winding device constitute 21.1 % each. In addition, 53.2 % of all surveyed subjects responded that trap pulling is the most dangerous task, followed by fish sorting 33.8 %, and trap dropping 9.1 %. As for the main items requested by fishermen for improving the trap winding device, 36.8 % indicated a method to easily lift the trap from the water to the work deck, and 31.6 % indicated a method to overcome the rope tension and prevent slip when pulling the trap to reduce the accidents. The small trap fishing vessel winding device proposed herein can increase the winding force by strengthening the rope contact area and friction coefficient via an appropriate contact angle between the driving roller of the winding device and the rope. When the contact angles between the driving roller and the rope are 1°, 5°, 9°, 14° and 19°, the rope tension showed a difference according to each contact angle. When the contact angle is 9°, the rope tension is the highest at 392.62 kgf. Based on these experimental results, a prototype winding device is manufactured, and 25 traps are installed on a rope with a total length of 100 m at 4 m intervals in the sea, and then the rope tension is measured during trap pulling. As a result, the rope tension increases rapidly at the initial stage of trap pulling and shows the highest value of 31.89 kgf, which subsequently decreases significantly. Therefore, it is appropriate to design the winding force of a small trap fishing vessel winding device based on the maximum tension value of the rope specified at the beginning of the trap pulling operation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.334-345
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• 2022

The Enforcement Decree of the Framework Act on the Management of Disasters and Safety Article 3-2 specifies two 'disaster management supervision agencies' for responding to shipping disasters. These are the Korea Coast Guard, which is an on-scene disaster-responding and coordinating agency, and the Ministry of Ocean and Fisheries, which is a government department, thereby leading to possibilities for confusion. In the case of shipping disasters, where a personnel entitled full power to deal with shipping disasters is designated and his/her powers and duties are clearly made, relationship of leading and supporting agencies is made clear, and command system is simplified, an efficient response to shipping disasters is made possible. In the management of shipping disasters, all the disaster management processes, that is, prevention-preparedness-response-recovery, should be dealt with systematically and consistently. Notably, to swiftly and efficiently cope with a disastrous situation, the decision-making and command system must be simplified. The establishment of a command system and decision-making must be made independently, based on expertise. In the US, irrespective of the type of disasters, the FEMA plays a leading role and the USCG responds a response to maritime disasters by establishing the Incident Command System or Unified Command System that is an incident management system. In the UK, the MCA supervises an event and responds to it, and the SOSREP has full power to work with command and coordination independently. SOSREP, among others, is necessary to prevent an inefficient dealing of a shipping disaster owing to confrontation between participants. With reference to such leading States' practice, the Korean government should make a standardized and simplified response to maritime disasters. This study deals with a new maritime disaster responding system and provides an idea of the revision of the existing legal regime.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.965-972
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• 2022

This is a basic study to establish marine activity criteria based on the seakeeping performance of less than 10-tons fishing vessels. These vessels account for approximately 95% of Korea's currently registered fishing vessels, and accidents and loss of life are also occurring during marine activities such as navigation, and fishing. Accordingly, the Ministry of Oceans and Fisheries has set a regulation of vessel traf ic control to restrict the operation of fishing vessels when the high seas watch takes effect, but it is applied equally without criteria according to the ship ton level and wave height; therefore, many differences may exist in ship fluctuations. Because the fluctuation of the ship owing to the wave height can be a factor in marine accidents by reducing the sense of boarding and performance of equipment, the seakeeping performance must be reviewed during waves to secure safe marine activities such as navigation and fishing. However, the review for the fishing vessel of established marine activity criteria based on the seakeeping performance is insufficient. Accordingly, the seakeeping performance was evaluated for a 10-ton class (G/T 9.77 tons) fishing vessel in Korea, and the level of marine activity according to the significant wave height and ship speed was interpreted by applying the operation and survival of the established seakeeping performance criteria. The analysis results indicated that the roll of the ship exceeded the operation criteria from 0.4m and the survival criteria from 2.2m. The pitch of the ship exceeded the operation criteria from 1.7m and did not exceed the survival criteria until 3.0m. However, the rolling exceeding the survival criteria from 2.2m may not be safe. Therefore, fishing vessels with less than 10-tons can leave before the high seas watch takes effect. However, they did not satisfy the criteria for evaluating the performance of the sea in relation to marine activities. Although this study was limitedly evaluated for 10-ton fishing vessels, it is expected to be of great help in preparing marine activity criteria.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.433-441
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• 2022

Light pollution is one of the factors that disturb coastal and island ecosystems. This study examined the factors causing light pollution in the islands in Daedohaehaesang National Park using nighttime satellite images. This study selected 101 islands with an area of 100,000 m² or more in Daedohaehaesang National Park, and measured the levels of light pollution of the selected islands by calculating mean nighttime radiance recorded in VIIRS DNB monthly images for January, April, August, and October 2019. Of seven districts of the park, The highest mean nighttime radiance was recorded in Geumodo district (17,666nW/m²/sr), followed by Geonumdo·Baekdo, Narodo, Soando·Cheongsando districts. By season, mean nighttime radiance in October was the highest at 9,509nW/m²/sr, followed by August, January, and April. Regression analyses show that the total floor area and the number of lighthouses in a 5 km buffer area had a statistically significant effect on mean nighttime radiance at all times, but those within the island did not, indicating that light pollution in islands in a national park where land development is strictly restricted is influenced by artificial lights in nearby areas. However, the total floor area of an island significantly affected mean nighttime radiance only in August, which appears to be attributed to the impact of intensive use of artificial light by visitors during summer vacation. The size of an island had a negative (-) effect on nighttime radiance. This negative effect suggests that light pollution is a type of ecological edge effect, i.e., the smaller island is more likely to have a relatively larger proportion of edge area that is affected by light emitted from the neighboring areas. The results of this study indicate that managing artificial lights in nearby areas is necessary to mitigate light pollution in islands in marine and coastal national parks.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.721-734
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• 2022

This study analyzed the spatio-temporal variation characteristics of major environmental factors such as primary productivity (PP), chlorophyll a, nutrients, sinking particle matters, and organic contamination and biochemical composition of surface sediment on a monthly basis for approximately 2 years around shellfish mariculture in Jaran Bay, Korea. In addition, PP in Jaran Bay was compared with that in other coastal areas and related policy plans were proposed. The average PP of the study area was high in summer and autumn with 6.43~115.43 mgC m^-2 hr^-1 range. This was lower than that in Gamak Bay and Masan Bay, whereas higher than that in Garorim Bay and the West Sea. The PP in coastal waters, where many aquaculture farms were distributed, significantly fluctuated. The different size compositions of phytoplanktons constituting chlorophyll a slightly varied by month, and little restriction existed on the productivity of phytoplanktons owing to the depletion of nutrients. Typically, the Redfield ratio was less than 16, indicating that nitrogen was the limiting factor for the growth of phytoplanktons. The biochemical composition of particulate organic matters in the water column showed the highest carbohydrates, but lipids and protein contents were high in surface sediments. The concentration of TOC and AVS of the surface sediments was high at inside of bay, and sometimes, exceeded the environmental criteria of fishing grounds. The organic C:N ratio of sediments ranged from 8.1 to 10.4 on average. PP had the highest correlation with chlorophyll a, nitrogen and protein of particle organic materials. Recently, chlorophyll a, DIN, and DIP of water column trends tended to decrease, however, the contamination of sediments increased. Considering the annual PP of 125.9 gC m^-2 yr^-1 and mariculture area (oyster) of 4.97 km², the annual carbon production from phytoplanktons was estimated to be about 625 tons, and the annual total wet weight of shellfish (oyster) was estimated to be about 6,250 tons.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.576-585
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• 1991

General procedures of seed preparation as conventional guide had been established in China before most of Korean literature documented them. ‘Chwijongbeob’ (method of seed select) was to select good quality of seeds and to discard the rest. In ‘Seonjongbeob’ (method of seed grading) although China employed only ‘Sooseonbeob’ (method of seed select with water), but seeds were selected in order of selection of seeds by winds, selection of seeds by sieve and selection of seed with water in Korea. As compared with the recent techniques, those methods were perfect techniques for selection of good quality seeds of rice, except for method of seed selection by salt water was developed. The method for measurement of seed moisture, and for measurement of melted snow, spoiled urine and extracted juice by boiling water with the bone of livestock were originated from ancient China. The farming books in Korea were more or less followed the above methods. However, these techniques were complicated and impractical interms of validity and rationality. Also, it is judged that these tchniques are more appropriate in dry areas and alkaline soil of China rather than in Korean conditions. The plowing is a work to begin farming, and is operated for air ventilation between atmosphere and earth. Also, this techniques was adopted in the farming books from the early to the late Chosun dynasty without changes. Fields were deep-plowed in the first, in fall (or in spring) and for cultivation, and were shallow -plowed in the second, in spring (or in summer) and in intertillage. The former was for water reserve and land preparation, and the later was for weed control with intertillage. However, plowing in fall which was different from fallowing in dry areas, was recommended in Korea (Jikseol). but was not practiced in Sejongsilrok. This was changed with time, and plowing for cultivation in Korea was interrelated with use of green manure crops, method of plowing of upseting plough, method of manure practice and sometimes dry plowing. In addition, until the 15th century method of using a kind of plowing-tool made of log as farm tools was created to support reclamation for enlargement of farm land in mountaineous and coastal areas. For desolate farm lands by many internal and external disturbances, one tried to recover yield ability by increasing labor productivity from the 17th or 18th century. To do this, ‘Banjongbeob’ (culture method by upset plowing weed control) and ‘Hwanubeob’(culture method by firing weed control) which were cultural methods of ancient China were readapoted but the results were not clearly informed. Also, the reality of those was reexamined in the end of the Chosun dynasty.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.201-211
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• 2022

The macroinvertebrate community in the Singal reservoir, Yedang and Juam lake was investigated three times from April 2021 to October 2021. Each lake was investigated by dividing it into inflow, middle-flow, and outflow. Additionally, sampling was conducted again by dividing it into the edge and center parts at each inflow, middle-flow, and outflow. Eight families of benthic macroinvertebrates were collected except for chironomids in the sampling sites. Dominant macroinvertebrates were investigated as chironomids, and Tubificidae was sub-dominant organisms. The density of macroinvertebrate community was higher in the edge area than in the center bottom of the lakes. The density of chironomids was low when the water level was high but was high when the water level was low. In the edge area of the middle-flow in Singal reservoir, the density of chironomids was 1,208 ind. m^-2 in April when the water level was high, but it increased to 1,401 ind. m^-2 in July when the water level was low. Similarly, the density of chironomids at the outflow of Yedang lake was high (1,990 ind. m^-2) in July when the water level was low. The density of chironomids also decreased along with the increasing water level at all edge areas of Juam lake. These results indicated that it will be necessary to consider the water level when studying macroinvertebrate communities in the lake.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.671-687
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• 2022

It has been reported that about 47% of groundwater wells within 10 km from the coastline in the western/southern coastal areas of Korea were affected by seawater. It has been interpreted that the cause of groundwater salinization is seawater intrusion. The Gilsan stream in the Seocheon area was a tidal stream until the Geumgang estuary dam was constructed and operated. Therefore, it is likely that the Gilsan stream catchment was deposited with sediments containing high-saline formation water prior to the use of landfill farmland at this catchment area. The groundwater in this study area showed EC values ranging from 111 to 21,000 µS/cm, and the water quality types were diverse including Ca(or Na)-HCO₃, Ca(or Na)-HCO₃(Cl), Na-Cl(HCO₃), Na-Cl types. It is believed that this diversity of water quality is due to the mixing of seawater and fresh groundwater generated by infiltration of precipitation and surface water through soil and weathered part. In this study, we discussed whether this water quality diversity and the presence of saline groundwater are due to present seawater intrusion or to remnant high-saline pore water in sediments during flushing out process. For this, rain water, surface water, seawater, and groundwater were compared regarding the water quality characteristics, tritium content, oxygen/hydrogen stable isotopic composition, and ⁸⁷Sr/⁸⁶Sr ratio. The oxygen/hydrogen stable isotopic compositions indicated that water composition of saline groundwaters with large EC values are composed of a mixture of those of fresh groundwater and surface water. Also, the young groundwater estimated by tritium content has generally higher NO₃ content. All these characteristics showed that fresh groundwater and surface water have continued to affect the high-saline groundwater quality in the study area. In addition, considering the deviation pattern in the diagrams of Na/Cl ratio versus Cl content and SAR (sodium adsorption ratio) versus Cl content, in which two end members of fresh surface-ground water and seawater are assumed, it is interpreted that the groundwater in the study area is not experiencing present seawater intrusion, but flush out and retreating from ancient saline formation water.

• Geophysics and Geophysical Exploration
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• v.26 no.2
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• pp.52-61
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• 2023

The use of ultra-high-resolution (UHR) seismic surveys to preceisly characterize coastal and shallow structures have increased recently. UHR surveys derive a spatial resolution of 3.125 m using a high-frequency source (80 Hz to 1 kHz). A digital streamer system is an essential module for acquiring high-quality UHR seismic data. Localization studies have focused on reducing purchase costs and decreasing maintenance periods. Basic performance verification and application tests of the developed streamer have been successfully carried out; however, a comparative analysis with the existing benchmark model was not conducted. In this study, we characterized data obtained by using a developed streamer and a benchmark model simultaneously. Tamhae 2 and auxiliary equipment of the Korea Institute of Geoscience and Mineral Resources were used to acquire 2D seismic data, which were analyzed from different perspectives. The data obtained using the developed streamer differed in sensitivity from that obtained using benchmark model by frequency band.However, both type of data had a very high level of similarity in the range corresponding to the central frequency band of the seismic source. However, in the low frequency band below 60 Hz, data obtained using the developed streamer showed a lower signal-to-noise ratio than that obtained using the benchmark model.This lower ratio can hinder the quality in data acquisition using low-frequency sound sources such as cluster air guns. Three causes for this difference were, and streamers developed in future will attempt to reflect on these improvements.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.188-196
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• 2023

Among marine accidents caused by bad weather, visibility restrictions caused by sea fog occurrence cause accidents such as ship strand and ship bottom damage, and at the same time involve casualties caused by accidents, which continue to occur every year. In addition, low visibility at sea is emerging as a social problem such as causing considerable inconvenience to islanders in using transportation as passenger ships are collectively delayed and controlled even if there are local differences between regions. Moreover, such measures are becoming more problematic as they cannot objectively quantify them due to regional deviations or different criteria for judging observations from person to person. Currently, the VTS of each port controls the operation of the ship if the visibility distance is less than 1km, and in this case, there is a limit to the evaluation of objective data collection to the extent that the visibility of sea fog depends on the visibility meter or visual observation. The government is building a marine weather signal sign and sea fog observation networks for sea fog detection and prediction as part of solving these obstacles to marine traffic safety, but the system for observing locally occurring sea fog is in a very insufficient practical situation. Accordingly, this paper examines domestic and foreign policy trends to solve social problems caused by low visibility at sea and provides basic data on the need for government support to ensure maritime traffic safety due to sea fog by factually investigating and analyzing social problems. Also, this aims to establish a more stable maritime traffic operation system by blocking marine safety risks that may ultimately arise from sea fog in advance.