• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.5
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• pp.223-233
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• 2018

The predictability of winter storm waves using KMA's operational wind forecasts has been studied to predict wind waves and swells in the East coast of Korea using SWAN. The nested model were employed along the East coast of Korea to simulate the wave transformation in the coastal area and wave dissipation term of whitecapping is optimized to improve swell prediction accuracy. In this study, KMA's operational meteorological models (RDAPS and LDAPS) are used as input wind fields. In order to evaluate model accuracy, we also simulate wind waves and swells using ECMWF reanalysis and KIOST WRF wind and they are compared with the KMA's operational wave model and the wave measurement data on the offshore and onshore stations. As a result, it has the lowest RMSE and the highest correlation coefficient in the onshore when the input wind fields are KMA's operational meteorological forecasts. In the offshore, all of the simulate results shows good agreements with similar error statistics. It means that it is very feasible to use SWAN model with the modified whitecapping factor and KMA's operational meteorological forecasts for predicting the wind waves and swells in the East coast of Korea.

• ALGAE
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• v.22 no.4
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• pp.287-295
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• 2007

Infection of free-living dinoflagellates by endoparasitic dinoflagellates of the genus Amoebophrya are thought to have significant impacts on host population dynamics and have long been proposed to be a potential biological agent for controlling harmful algal bloom (HAB). To understand the impact of Amoebophrya on particular host species, however, it is necessary to quantify aspects the parasites life cycle. Here we used cultures of Amoebophryahost systems from Jinhae Bay, Korea to determine, parasite generation time, and dinospore survival and infectivity. The proportion of host cells infected by Amoebophrya sp. changed sharply from 5% to 87% with increasing dinospore:host inoculation ratios. In the absence of H. triquetra, most free-living dinospores died within 72 hours and their ability to infect host cells decreased remarkably in a day. The relatively short free-living phase of Amoebophrya suggests that the spread of infections is most likely to occur during seasons of high host abundance, as that is when dinospores have the greatest chance of encountering host cells. Infection of host cells inoculated with dinospores during the day was higher than when inoculated during the night, suggesting that infection rates might be related to environmental light conditions and/or diurnal biological rhythm of host species. Total generation times of parasite strains from a thecate dinoflagellate Heterocapsa triquetra were nearly the same regardless of dinospore:host inoculation ratios, representing 54 ± 0.5 h in a 1:1 ratio and 55 ± 1.2 h in a 20:1 ratio. Dinospore production of Amoebophrya sp. infecting Heterocapsa triquetra was estimated to be 125 dinospores per a strain of Amoebophrya sp. There is a growing need to maintain a variety of host-parasite systems in culture and to examine their autecology under various environmental conditions. Such studies would be very helpful in understanding ecological role of these parasites, their overlooked importance in the flow of material and energy in marine ecosystem, and their practical use as biological control agents applied directly to areas affected by HAB.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.657-661
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• 2009

Liquid microparticulated seaweed calcium was manufactured via a wet grinding process. Thereafter, different forming agents such as cyclodextrin, gum arabic, and Na-caseinate were added to the liquid calcium, which was then spray-dried to investigate the quality of the powdered calcium treatments. The moisture contents of samples were approximately 2%. It was also determined that the different kinds of forming agents did not affect the spray drying efficiency. In addition, calcium solubility was the highest in a solution of pH 2. In buffer solution and vinegar, the powdered calcium made with gum arabic showed the highest solubility among the treatments. The calcium contents of all the powdered microparticulate seaweed calcium samples were about 28%, and calcium content was not affected by the forming agents. The spray-dried calcium powder made by spray drying with gum arabic had the highest water vapor uptake, whereas the seaweed calcium was stable in terms of water adsorption. The results of SEM observations indicated that a portion of the spray-dried calcium powders were in nano-scale after wet-grinding. Among the treatments, the use of saccharides as a forming agent resulted in the most uniform particle distribution after spray-drying.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.1-6
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• 1987

This study was designed to evaluate the characteristics, land use and genesis of well adapted paddy soils. They were mostly classified as the Haplaquepts in the U.S.D.A soil taxonomy and as the Grey soils in the Japanese soil classification system. The proportion of these soils in the total acreage of paddy lands was thirty three percents. The fifty four percents in average of these soils were distributed on the local valley and fans on gentle slopes developed from granite, granite gneiss and shale parent materials. The rests were on the fluvio-marine deposits and alluvial deposits. The soils were characterized with prominant development of gleized horizons and clayey or fine loamy textured category. The available soil depth and the ground water level were relatively deep. The base saturation percent were high with weak acidic pH. The potential productivity of these soils was high.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1620-1625
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• 2004

To advance fisheries, we set developmental directions of fishery information by grasping present situations and analyzing maritime & fisheries issues. We promote various policies through effective systematical information data bases, based on both control and utilization of oceanic resources. For these puposes, it is imperative that we set up fisheries communication networks. There are satellite assisted informational networks to assist fishing vessels with their marine based movements. However, there's no hope for poorly equipped fishermen to adopt this network because of extravagant network call charges. So we think that using existing SSB communication system is the best plan. We organize fishery communication network by HF SSB communication which doesn't have operational costs. We build wireless transmitting and receiving stations that are basic systems of informnation, and equip wireless data communication systems by the use of wireless communication network protocols in coastal stations. It is necessary that a fish boat has a terminal device for wireless data communication. In this research we can conclude that if we transmit the location of a fishing boat in-real time through GPS channels then we propose that some methods be formulated to able terminal devices on fishing boats to collect various types of information, such as meteorological and oceanic conditions.

• Applied Biological Chemistry
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• v.1
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• pp.55-61
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• 1960

The amino acid compositions of the protein and the nonprotein fractions obtained from a marine brown alga, 'Undaria pinnatifida' were determined by use of Ion Exchange Column Chromatography. The protein nitrogen in the alga was about ten times of the nonprotein nitrogen. Nonprotein fraction obtained from the extraction with 80 percent ethanol contains considerable amount of tree citrulline. Alanine content in the alga was the highest (about 1 per cent in dry weight) and one third of which was found in free state. The amino acid composition of the alga was well balanced and the content of the essential amino acids were relatively higher, than soybean protein. In addition, several peptide like substances were fractionated from nonprotein fraction, in which one way identified as a naturally occurring new tripeptide composed of alanine, glutamic acid and aspartic acid, and the remaining unknown substances are under investigation for the further information.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.3
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• pp.187-194
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• 2012

This study surveyed the fishing efficiency for Japanese common squid based on improvements made to LED fishing lamps by utilizing the training ship of Gangwon Provincial College. The training ship, Haesong-ho (24 tons), was equipped with seventy-two 150W electric power LED fishing lamps (10.8kW), and their fishing efficiency and fuel consumption level were surveyed for a total of ten times during the period between June 15, 2009 and July 27, 2009. In addition, the training ship was equipped with seventy-one 300W electric power LED fishing lamps (21.3kW) and their fishing efficiency and fuel consumption level were surveyed for a total of five times during the period between January 17, 2010 and August 4, 2010. In order to compare the fishing efficiency of LED fishing lamps, the catch of another fishing vessel equipped with Metal Halide (MH) fishing lamps of 120kW for the same period and at the same fishing grounds. The fuel consumption levels during the fishing operation of Haesong-ho was about 1,047.7 liters which was approximately 19.9% of the total fuel consumption level of 5,262.6 liters, and the fuel consumption level per operation hour was on average 9.2 liters. The number of Japanese common squid caught by the LED fishing lamp-equipped fishing vessel ranged from 12 to 1,640 squid for each fishing trial and the average quantity was 652. The number of Japanese common squid caught by the MH fishing lamp-equipped 10 fishing vessels ranged from 40 to 4,800 squid and the average quantity was 2,055. The fishing of Japanese common squid was done by the use of hand lines and an automatic jigging machine. The number of Japanese common squid caught per hand line and a single roller of the automatic jigging machine was in the proportion of 50.8% to 49.2% with respect to the LED fishing lamp-equipped fishing vessel. However, the number of Japanese common squid caught per hand line and a single roller of the automatic jigging machine was in the proportion of 86.4% to 13.6% with respect to the MH fishing lamp-equipped fishing vessel where most of the catch was made by hand lines. On the other hand, in comparing the number of Japanese common squid caught per automatic jigging machine, the number of squid caught by the LED fishing lamp-equipped fishing vessel was about the same or greater than the number of squid caught by the MH fishing lamp-equipped fishing vessel.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.1
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• pp.1-11
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• 2017

Fishing pots are one of the important fishing gears in our coastal and offshore fisheries. In terms of a sustainable use of marine resources, there are concerns about the ghost fishing by lost pots. It is reported that 10 to 70% of the pots are abandoned or lost annually. This study is to compare the catching efficiency of drum type whelk pots that are made of biodegradable nets to those made of the ordinary nets, in the eastern coast of Korea. Five types of drum pots were used with combination of biodegradable nets and ordinary (PA, PE) nets applied to the main and funnel parts of the pots: pots with biodegradable nets (Bio+Bio); pots with PE net (PE+PE); pots with body and funnel made of biodegradable nets and PE nets respectively (Bio+PE); pots with body and funnel made of PE nets and PA nets respectively (PE+PA); pots with body and funnel made of PE nets and biodegradable net respectively (PE+Bio). Field experiments were conducted from June $18^{th}$, 2015 to August $7^{th}$, 2015 using a commercial fishing vessel in the Uljin waters on the eastern coast of Korea. Two fleets of pots with one hundred in each, 20 pots of each type, were casted for 8 to 15 days to analyze their catching efficiency. The catch of target species, whelks, was 202,563.0 g with catch rate of 38.7% of the total catch, while the bycatch was 320,709.7 g with the rate of 61.3% of the total catch. The catch of whelks was the highest in the Bio+PE pots (46,020.3 g), followed by the Bio+Bio pots (42,027.5 g), the PE+Bio pots (41,849.9 g) and the lowest being PE+PE pots (38,054.2 g). Compared to the conventional pots, the pots with biodegradable nets on the body or entrance part had slightly higher catch rate for both the target species and the bycatch. The PE+PE had the lowest catch rate. There is no significant difference in catch between the pots with biodegradable nets and the ordinary nets for the target species such as Buccinum opisthoplectum, Neptunea eulimata, Buccinum striatissimum. Consequently, using biodegradable nets for the conventional whelk pots can reduce ghost fishing by lost gears while keeping the performance of the pots.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.69-76
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• 2020

The sound signal radiated from an underwater source is received by the hydrophone of the system, including multi-path time-delay and multi-path signal by sea surface and bottom reflection. The system using a time-delay between received signals for the source localization shows performance degradation due to incoherence by the multi-path propagation environment and the disturbance of a marine environment. Various types of array and signal processing have been used for robust source range and bearing estimation in this environment. In this paper, we use a line array composed of doublet array and an estimated time-delay correction method for robust localization performance in a multi-path propagation environment. Three doublet arrays are located on the same line, and the time-delay between signals received on each doublet array is estimated in a two-step procedure. The estimated time-delay value is obtained by the cross-correlation function and corrected by the interaction formula between the center-frequency of received signal and the geometry of the array with respect to aperture. By this proposed procedure, the range and bearing of source from array were calculated. In order to confirm the validity of the proposed method and array, we simulated localization and estimation using the Monte-Carlo method.

• The Korean Journal of Quaternary Research
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• v.1 no.1
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• pp.3-20
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• 1987

With regard to the Quaternary formations in the Korean Peninsula, very few studies have been done specially from a stratigraphic viewpoint. The alluvial sediments filling in the valleys have often been considered as the only formation of Quaternary age (more precisely of the Holocone) and so the Pleistocene was regarded as an erosional or nondepositional episode. This is apparently evident from a quick look at the general geological maps of the Peninsula, which show a lithological sequence of Mesozoic or Paleozoic substrata immediately overlain by Holocene alluvium. Likewise, the Pleistocene period was described in terms of unconformity in most local or regional stratigraphical successions of the Peninsula. Recently several different types of Quaternary formation, besides the so-called Holocene alluvium in the valley plain have been found around the Peninsula. They consist of coastal deposits, marine or fluviatile terrace deposits, ancient valley fill deposits or slope deposits. Some parts of the volcanic sediments in Jeju Is. are also known as the Quaternary sequence. Thus the Quaternary deposits in the Peninsula are far more developed than previously known to gelolgists. Moreover the importance of Quaternary research became recently apparent in Korea due to the shortage of raw materials and to the policy of an optimum land-use. Advanced constructions and land reclamation have required more precise engineering parameters of loose materials and an estimation of land stability. This does not imply only the engineering, or the structural properties of the loose material, but at the same time the basic study of the sediments from the stratigraphical and environmental viewpoints has been necessary. In this connection, Quaternary outcrops specially along the coastal fringe of the Peninsula have been mapped, profiled and sampled for sedimentological, clay-mineralogical and palaeomagnetic studies. All these results are compiled for the core of the Quaternary stratigraphy of the Peninsula.