• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.85-93
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• 2021

The seventy percentage of Korean Peninsular is covered by the mountainous area, and the depth of west sea and south sea is relatively shallow. Therefore, a large scale land reclamation from the sea has been implemented for the construction of industrial complex, residental area, and port and airport facilities. The common problem of reclaimed land is consisted of soft ground, and hence it has low load bearing capacity as well as excessive settlement upon loading on the ground surface. The hollow concrete block has been used to reinforce the loose and soft foundation soil where the medium-high apartment or one-story industrial building is being planned to be built. Recently the earthquakes with the magnitude of 4.0~5.0 have been occurred in the west coastal and southeast coastal areas. Lee (2019) reported the advantages of hollow concrete block reinforced shallow foundation through the static laboratory bearing capacity tests. In this study, the dynamic behavior of hollow concrete block reinforced sandy ground with filling the crushed stone in the hollow space has been investigated by the means of shaking table test with the size of shaking table 1000 mm × 1000 mm. Three types of seismic wave, that is, Ofunato, Hachinohe, Artificial, and two different accelerations (0.154 g, 0.22 g) were applied in the shaking table tests. The horizontal displacement of structure which is situated right above the hollow concrete block reinforced ground was measured by using the LVDT. The relative density of soil ground are varied with 45%, 65%, and 85%, respectively, to investigate the effectiveness of reinforcement by hollow block and measured the magnitude of lateral movement, and compared with the limit value of 0.015h (Building Earthquake Code, 2019). Based on the results of shaking table test for hollow concrete block reinforced sandy ground, honeycell type hollow block gives a large interlocking force due to the filling of crushed stone in the hollow space as well as a great interface friction force by the confining pressure and punching resistance along the inside and outside of hollow concrete block. All these factors are contributed to reduce the great amount of horizontal displacement during the shaking table test. Finally, hollow concrete block reinforced sandy ground for shallow foundation is provided an outstanding reinforced method for medium-high building irrespective of seismic wave and moderate accelerations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.11-36
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• 2021

The solar annual (Sa) and semiannual (Ssa) tides account for much of the non-uniform annual and seasonal variability observed in sea levels. These non-equilibrium tides depend on atmospheric variations, forced by changes in the Sun's distance and declination, as well as on hydrographic conditions. Here we employ tidal harmonic analyses to calculate Sa and Ssa harmonic constants for 21 Korean coastal tidal stations (TS), operated by the Korea Hydrographic and Oceanographic Agency. We used 19 year-long (1999 to 2017) 1 hr-interval sea level records from each site, and used two conventional harmonic analysis (HA) programs (Task2K and UTide). The stability of Sa harmonic constants was estimated with respect to starting date and record length of the data, and we examined the spatial distribution of the calculated Sa and Ssa harmonic constants. HA was performed on Incheon TS (ITS) records using 369-day subsets; the first start date was January 1, 1999, the subsequent data subset starting 24 hours later, and so on up until the final start date was December 27, 2017. Variations in the Sa constants produced by the two HA packages had similar magnitudes and start date sensitivity. Results from the two HA packages had a large difference in phase lag (about 78°) but relatively small amplitude (<1 cm) difference. The phase lag difference occurred in large part since Task2K excludes the perihelion astronomical variable. Sensitivity of the ITS Sa constants to data record length (i.e., 1, 2, 3, 5, 9, and 19 years) was also tested to determine the data length needed to yield stable Sa results. HA results revealed that 5 to 9 year sea level records could estimate Sa harmonic constants with relatively small error, while the best results are produced using 19 year-long records. As noted earlier, Sa amplitudes vary with regional hydrographic and atmospheric conditions. Sa amplitudes at the twenty one TS ranged from 15.0 to 18.6 cm, 10.7 to 17.5 cm, and 10.5 to 13.0 cm, along the west coast, south coast including Jejudo, and east coast including Ulleungdo, respectively. Except at Ulleungdo, it was found that the Ssa constituent contributes to produce asymmetric seasonal sea level variation and it delays (hastens) the highest (lowest) sea levels. Comparisons between monthly mean, air-pressure adjusted, and steric sea level variations revealed that year-to-year and asymmetric seasonal variations in sea levels were largely produced by steric sea level variation and inverted barometer effect.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.1
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• pp.57-68
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• 2021

In order to collect basic data for the improvement of fishing systems in coastal improved stow net fishery, a questionnaire survey and on-site hearing were conducted from May 10 to June 11, 2019 on the basic items of coastal improved stow net fishery and safety accidents that occurred during fishing operation. The questionnaire for the survey on the actual conditions of coastal improved stow net fishery consisted of a survey on basic matters (six questions) and a questionnaire (six questions) on safety accidents occurring during fishing operation. The results of the survey on basic items were analyzed by region (Incheon, Seocheon, Gunsan and Mokpo), by the captain's age (less than 50 years of age, 50 to 60 years and more than 60 years of age), by the captain's career (less than 20 years, 20 to 30 years, 30 to 40 years and more than 40 years) and by the age of fishing vessel (less than 10 years, 10 to 20 years and more than 20 years). According to the survey on basic items of coastal improved stow net fishery such as the captain's age, the captain's career, the age of fishing vessel, the fishing nets in use, the crews on board and the operation days per voyage by region, the average captain's age was 55.7 years, the average captain's career was 20.5 years, the average age of fishing vessels was 9.0 years, the average numbers of nets used by fishing boats was 14.0 sets, the average numbers of crew on board a fishing boat was 4.4 persons and the average numbers of operation days per voyage was 4.9 days (p < 0.05). As a result of the survey on safety factors during fishing operations, such as experience of ship accidents, major causes of ship accidents experienced, causes of ship accidents (first priority), experience of human accidents, major causes of human accidents, and causes of human accidents (first priority), more than 96% of the respondents experienced ship accidents including collisions with other vessels or fishing gear during fishing operations. The most significant cause of the accident was the other's fishing gear installed in the fishing grounds. The first possible causes of ship accidents during fishing operations were found to be other fishing gear installed in fishing grounds, steering or engine failure, and inability to avoid accidents during casting and hauling nets. The survey of the experience of human accidents, such as injuries or sea falls, showed that more than 90% of the respondents experienced human accidents during fishing operations. The most important cause of accidents experienced during fishing operations was stucked in a fishing gear during casting and hauling nets. The first important causes of accidents during fishing operations were movement of the fishing gear during casting and hauling nets, damage of the fishing gear such as rope cutting. The results are expected to be provided as a basic data to prevent safety accidents occurring during fishing operation and improve the fishing system in the coastal improved stow net fishery.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.339-344
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• 2013

Water vapor isotopes can be excellent tools for understanding complex mechanisms in the water cycle and atmospheric hydrological cycle and they can be applied to various fields of paleoclimatology, atmospheric science, hydrogeology, oceanography, and ecohydrology. Thus, studies of global or local transport of water vapor may be able to provide a very useful clue to better understand the movements of water and energy in the atmosphere, hydrosphere and biosphere. In this study, the isotopic compositions of water vapor have been observed for moisture transport during the passage of Typhoon Bolaven at Korea Polar Research Institute (KOPRI), Incheon, in the western part of Korea, from August 27 to August 29, 2012. In the clear sky, the isotopic compositions of water vapor at KOPRI exhibited relatively higher isotopic ratios, which were near isotopic equilibrium with sea surface water (${\delta}^{18}O$=-14‰). On the other hand, a largely depleted isotopic ratios in surface water vapor were observed in association with the passage of Typhoon Bolaven (approximately 10‰ depleted compared to the clear sky). The fact that the isotopic minima in water vapor are encountered during the onset period of the Typhoon Bolaven with increases of relative humidity, which is consistent with, so called, "the amount effect".

• Journal of Korea Port Economic Association
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• v.36 no.4
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• pp.53-74
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• 2020

It is important to understand the current status and problems of the North Korean shipping industry to prepare for inter-Korean trade in the future era of peace in the Korean Peninsula. In this study, the status of vessels calling in North and South ports was analyzed by year, cargo type (vessel type), and North Korean port type using Port-MIS data. In particular, considering the three years (2006-2008) in which inter-Korean trade was the most active, the flow of maritime transport was analyzed by visualizing data on vessels' arrival and departure in the North and South ports. Findings revealed that sea transportation between Haeju-Incheon was the most frequent, while the Haeju-Mokpo and Nampo-Incheon routes in the west coast area, and the Najin-Busan route in the east coast area were active. With reference to general cargo vessels, ports located on the west coast of Korea tended to operate between those located on the North coast of North Korea and on the east coast of South Korea. These results are expected to serve as a basis for establishing research and policies related to coastal shipping between the two Koreas in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.1-7
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• 2009

The toxicity of two species of puffer fish, Takifugu poecilonotus (Heuinjeombok) and T. vermicularis (Gukmaeribok) collected from the coastal regions of Korea was determined using a mouse bioassay. In the T. poecilonotus collected in Jeju and Tongyeong, the proportion of toxic specimens containing ${\ge}10$ mouse units (MU) per gram exceeded 95% for the skin, liver, ovary, and fin, and approximately 30% for the testis and muscles. In each of the organs, the highest toxin levels were 79 MU/g in the muscle, hundreds (158-365) of MU per gram in the fin, intestine, testis, and gallbladder, but thousands (1,147-2,406) of MU per gram in the skin, liver, and ovary. In T. vermicularis collected from Incheon and Gunsan, the proportions of toxic specimens were 100% for the gallbladder, and 56-68% for the skin, fin, liver, and intestine however, no toxic muscle specimens were noted. The highest toxin scores were below 10 mouse units (MU) per gram in the muscle, 20-94 MU/g in the skin and fin, 319 MU/g in the intestine, and thousands (1,548-4,624) of MU per gram in the liver, gonad, and gallbladder. The toxicity in the muscle of T. vermicularis was deemed acceptable for human consumption, whereas the toxicities in the muscle of T. poecilonotus and the skin of both species of puffer fish were significantly high, such that special attention may be required when the fish is intended for human consumption.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.489-495
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• 2011

Fossil fuel energy has become a worldwide environmental issue due to its effect on global warming and depletion in its supply. Therefore, the interest in developing alternative energy source has been rising. Ocean energy, especially, has gained strength as an alternative energy source for its unlimited supply with low secondary risks. Among all the ocean energy, the west coast of Korea holds the field of large-scale energy development because of its distinctive tidal range. Tidal power plant construction at the sea may expedite multi development effects such as bridge roles, tourism resource effects and adjustability of flood inundation at the inner bay. This study introduces the validity of tidal power plant construction at Garilim Bay in west coast of Korea by examining anticipated hydraulic characteristics using EFDC model. Through EFDC numerical simulations, the feasibility of Garolim Bay as a tidal power plant field has been proved. And the most effective tidal power plant construction would be to install hydraulic turbine in the west side of bay entrance where ebb current is stronger, and install water gate in the east side of bay entrance where the flood current is superior.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.142-149
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• 2019

In this study, the past erosion history and current status in the CHUNG-UI beach of Eulwang-dong, Jung-gu, Incheon-Si, South Korea were investigated and analyzed the wave with wave-induced current to investigate the causes of coastal erosion. As a result, the significant wave height ($H_{1/3}$) was in the range of 0.07~1.57 m and the mean value was 0.21 m. The maximum wave height ($H_{max}$) was in the range of 0.02-4.76m and the mean value was 0.27m. The vertical wave height and cycles were estimated through numerical model experiments of wave transformation. The 50-year frequency design wave height ranged from 0.82m to 3.75m. As a result of the experiment of wave-induced current, wave-induced current in the CHUNG-UI beach was decreased after the installation of the Detached breakwater and the Jetty. On the other hand, when the crest elevation was increased up to 5 m, there was no significant change, but when the crest elevation was increased to 8m, strong wave-induced current occurred around the submerged breakwaters due to lowered depth of water. In addition, the main erosion of the CHUNG-UI beach is due to the intensive invasion of the wave characteristics coming from the outer sea into the white sandy beach. The deformation of the wave centered on the front of the sandy beach caused additional longshore currents flowing parallel to the sandy beach and rip currents in the transverse direction, thus confirming that the longshore sediment was moved out of the front and out of the sea. The results of this study can be used as preliminary data for the recovery of the sand and the selection of efficient erosion prevention facilities.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.106-111
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• 2008

Six standard methods for marine ecotoxicological tests were established(or applicated) using marine decomposer, primary producers and consumers. Development processes referred to the standard methods established by USEPA(United States Environmental Protection Agency), international organizations and European methods. However, the standard test species were selected among the domestic species generally found in the Korean waters and sediments. The test methods provide the culture/maintenance of test species, test methods, reproducibility and quality acceptance criteria etc. A total of nine test species were designated including bioluminescent bacteria(Vibrio fischeri), diatom(Skeletonema costatum), seaweed(Ulva pertusa), rotifer(Brachionus plicatilis), benthic copepod(Tigriopus japonicus), benthic amphipods(Mandibulophoxus mai, Monocorophium acherusicum), and fishes(Oryzias latipes, Paralichthys olivaceus). These test species represent the decomposer, primary producer and consumers in marine trophic system in Korean coastal ecosystems, and we recommend the "battery test" including at least one species from the each trophic level for marine ecotoxicological test.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.846-853
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• 2016

This study prioritizes Noxious Liquid Substances (NLS) transported by sea via a risk-based database containing 596 chemicals to prepare against NLS incidents. There were 158 chemicals transported in Korean waters during 2014 and 2015, which were prioritized, and then chemicals were grouped into four categories (with rankings of 0-3) based on measures for preparedness against incident. In order to establish an effective preparedness system against NLS spill incidents on a national scale, a compiling process for NLS chemicals ranked 2~3 should be carried out and managed together with an initiative for NLS chemicals ranked 0-1. Also, it is advisable to manage NLS chemicals ranked 0-1 after considering the characteristics of NLS specifically transported through a given port since the types and characteristics of NLS chemicals relevant differ depending on the port. In addition, three designated regions are suggested: 1) the southern sector of the East Sea (Ulsan and Busan); 2) the central sector of the South Sea (Gwangyang and Yeosu); and 3) the northern sector of the West Sea (Pyeongtaek, Daesan and Incheon). These regions should be considered special management sectors, with strengthened surveillance and the equipment, materials and chemicals used for pollution response management schemes prepared in advance at NLS spill incident response facilities. In the near future, the risk database should be supplemented with specific information on chronic toxicity and updated on a regular basis. Furthermore, scientific ecotoxicological data for marine organisms should be collated and expanded in a systematic way. A system allowing for the identification Hazardous and Noxious Substances (HNS) should also be established, noting the relevant volumes transported in Korean waters as soon as possible to allow for better management of HNS spill incidents at sea.