• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.4
• /
• pp.325-332
• /
• 2008

To characterize the initiation, propagation and termination of Cochlodinium polykrikoides blooms in the southeast coastal waters of Korea, 2007, we have analyzed the data set of phytoplankton composition, physical and chemical water properties, and meterological data. The development of C. polykrikoides bloom in 2007 can be summarized in three steps. The first stage from middle of July to end of August was characterized by an unusually persistent and strong southerly wind. C. polykrikoides blooms established already by the strong wind in the middle of south coastal waters were advected intermittently into the study area. Accordingly, highly variable cell densities of C. polykrikoides were observed. At the second stage a favorable growing conditions for C. polykrikoides was developed, which was directed by changes in wind direction from south to northeast and thus enhanced transportation of offshore waters into inshore (August 8 to 30). C. polykrikoides bloom occurred through typical mechanism and showed high cell density. The last stage was represented by disappearance of C. polykrikoides. Typoon 'Nari' carrying heavy rain brought an unfavorable habitat to C. polykrikoides. Low saline condition formed in coastal water due to typoon effects continuously drove the dominant species to diatoms and flagellates which were prevailing over C. polykrikoides in this circumstances(from the middle of September). These stepwise processes could be the causative mechanism of the extraordinarily persistent C. polykrikoides bloom observed in southeast coastal water of Korea, 2007.

• The Journal of Fisheries Business Administration
• /
• v.22 no.1
• /
• pp.1-52
• /
• 1991

This study deals with the evolutional history of the holding and utilization of fisheries resources in Korea. Fisheries resources have the basic characteristics of the density dependent self-regulating renewable and common property resources, Irrational utilization of fisheries resources is mainly due to the unlimited access to the resources. The holding and utilization of fisheries resources in Koryo era was opened to everyone. But it was nationalized in the early Yi Dynasty. The purpose of its nationalization was to provent the paticular powered-man with their monoplized holding and to levy fisheries tax. Eoeop-peop, the first modern fisheries law in Korea, was enacted as a part of the invasion policy of Japan in 1908. With the japanese annexation of Korea in 1910, the Japanese Government established a new institutional system of fisheries as a part of an overall reformation of the institutional for an implementation of the colonial policy. It was very the new enacted Fisheries Law (Gyogyorei). Also the Government enacted compulsorily another new Fisheries Law (Chosen Gyogyorei) with its adjunct laws and regulations revise the institutional system of fisheries on May 1, 1930. After Eoeop-peop enactment, the fisheries resources in Korea could be used only under the license, permission, and statement. After Korea was from Japan in 1945, Korea Government at last enacted the new fisheries law (Susaneop-peop) in 1953. The goal of Susaneop-peop was to achive the general usage and protection of the fisheries resources, and to attain the development and democratization of the fishery in Korea. This law was amended 13 times until 1990. The license fishery have a legal right on the fishery, called a fishery rigt. This right means a right of exclusive occupation and utilization of a unit of the inshore fishing grounds. The main evolutional issues of license fishery are as the following : 1) the foundation of the exclusive usable fishery right(1911, Gyogyorei), 2) the deletion of the settled U9space lift net and settled space sein net fishery, and the expansion of the cooperative fishery-No.1, 2, and 3 type cooperative fishery-(3rd amendment, 1963), 3) the deletion of the No.2 and 3 type cooperative fishery, and the separation of the culturing fishery in No.1 and 2 type culturing fishery (13th amendment, 1990). The effective period of the license fishery was amended as the following : 1) 1908(Eoeop-peop) : within 10 years, renovation system, 2) 1929(Chosen Gyogyorei) : within 10 years, unlimited extension system, 3) 1971. 7th amendment : 10 years, renovation system, 4) 1972. 8th amendment : 10 years, only 1 extension system, 5) 1975. 9th amendment : 5-10 years, only 1 extension system, 6) 1990.13th amendment : 10 years, within 10 years of total extensional years. The priority order of the fishery license was established in 1953 (Susaneop-peop). The amendment of it is as follows : 1) 1953. enactment \circled1 the fishing grounds that the fishery right is extablished 1st order : the existing fishery right man, unlimited renovation 2nd order : the corporate that the regional fisherfolk organized 3rd order : the rest experienced fishermen \circled2 new fishing grounds 1st order : the corporate that the regional fisherfolk organized 2nd order : the rest experienced fishermen 2) 1971. 9th amendment \circled1 the fishing grounds that the fishery right is established 1st order : the existing fishery right man, unlimited renovation 2nd order : the Eochongye that the regional fisherfolk organized 3rd order : the regional fishery cooperative that the regional fisherfolk organized 4th order : the rest experienced fishermen \circled2 new fishing grounds 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd order : the rest experienced fishermen 3) 1981. 10th amendment \circled1 the inside of No.1 type cooperative fishing grounds 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd orer : the rest experienced fishermen 4) 1990. 13th amendment \circled1 No.1 type cultural fishery 1st order : the Eochongye that the regional fisherfolk organized 2nd order : the regional fishery cooperative that the regional fisherfolk organized 3rd order : the rest experienced fishermen \circled2 No.2 type cultural and settle fisher : general priority order The effective period of the permission fishery was amended 6 timed. First, it was within 5 years and renovation system (Eoeop-peop). Now it is 5 years and renovation system. The effective period of the statement fishery was amended 4 times. First, it was within 5 years, and then was amended within 3 years(Chonsen Gyogyorei). Now it is 5 years.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.1
• /
• pp.20-35
• /
• 2002

We studied the fishing ground of a yellowtail and oceanographic conditions around Chujado and Marado around Jeju Island from autumn to winter. Also we investigate the forming mechanism of fishing ground around Marado, which shows the best catch of yellowtail near Jeju island. The obtained results are summarized as follow ; 1. When the high temperature water about 15.0∼19.0 in depth of 50m distributed around Chujado and Marado, the fishing ground of Yellowtail is shows a good catch. On the contrary, when the low temperature water about 11.0∼14.0 is shows a poor catch. 2. Fishing grounds of yellowtail by handline fishing are formed with a school of Yellowtail migrating southward from the coastal sea of Korea and slaying around Marado to winter and spawn due to following factors. Firstly, a front of temperature and salinity is formed between inshore water and oceanic water around Marado. Secondly, small-size eddies and excellent horizontal and vortical mix which is created by strong tide and geographical features including irregular underwater ground and an isolated island. An abundant school of yellow tails stays in front of the tide where a good fishing ground was made.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.3
• /
• pp.163-173
• /
• 2001

The dynamic behavior characteristics of a small fishing crane for inshore and coastal fishing vessels was experimentally analyzed in order to improve the fishing operation and to reduce considerably manual work of fisherman. The small fishing crane was designed to be controlled electro-hydraulically by means of proportional valves and solenoid valves, and also to be controlled the speed of each operation. The dynamic behavior characteristics was investigated by measuring the changes of parameters such as oil pressure, swing angle of load, load tension, the lifting angle and the swing angle of crane arm when the arms extended in a side way was given a test load. The results obtained are summarized as follows: 1. The designed small fishing crane can be proportionally controlled by means of proportional valves and rapidly by operating the solenoid valves, respectively. The capacity, turning angle, maximum reach of crane were 2 T-M, $180^\circ$, 3.7m, respectively. 2. The vertical change of crane arm on the extension of lifting cylinder was $1.2^\circ$/cm, and the swing speed of crane arm due to the extension of swing cylinder by on/off operations of solenoid valves was $15^\circ$/sec, with the swing period of 1.4 sec and the angle fluctuation of $\pm$11.0$^{\circ}$. 3. When changing simultaneously the horizontal and vertical positions of the lifting load by on/off operations of solenoid valves, the swing and lifting speeds of crane arm were $4.46^\circ$/sec and $6.4^\circ$/sec, respectively. 4. The movements of the designed crane were particularly smooth as they are controlled with the aid of proportional valves than by means of solenoid valves.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.5
• /
• pp.603-613
• /
• 1996

Hydrographic conditions (temperature, salinity, dissolved oxygen), nutrients, chlorophyll-a and suspended solid have been studied in the southwestern coastal area of Cheju Island from April 1993 to March 1994. Vertical profile of temperature, salinity and chemical properties (nutrients, chlorophyll-a) distribution in th southwestern sea of Cheju Island showed a upwelling feature. Although it was not clear in winter season, it seems to continued through out the year. In the surface water at the upwelling areas, the ranges of dissolved oxygen, nitrate, phosphate and silicate was $3.30\~8.43\;ml/l,\;0\~7.12{\mu}g/l,\;0.03\~1.75{\mu}g-at/l\;and\;2.75\~22.32\;{\mu}g-at/l$l, respectively. Nutrients was higher in the shore water than in the offshore water, because sufficient supply of nutrients from the bottom water by coastal upwelling. In November, especially high concentration silicate was observed at all the stations and depth in the study area. At all station of bottom water (down to the depth of 60 meter), concentration value of dissolved of gen was as high as 8 ml/l. Mean values of N/P was 8.0, lower than Redifield ratio of 16. The mean values of Si/P was observed to 46.3 in southwest of Cheju Island. Concentration of chlorophyll-a was in the range of $0.04\~2.36\;{\mu}g/l$. Concentration of chlorophyll-a in surface orator at all station was especially higher in spring than in other seasons. Mean concentration value of suspended solids was 3.14 mg/l $(0.75\~8.47\;mg/l)$. Ratio of the volatile suspended solids to the suspended solids was higher in the inshore water $(53\%)$ than in the offshore water $(46\%)$, and higher in the surface water than in the bottom water.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.5 no.1
• /
• pp.59-69
• /
• 2000

Environmental factors and phytoplankton community have been bimonthly investigated in order to clarify the bioecological characteristics of coral habitats around Moonsom at the southern Cheju Island from September 1995 to July 1996. Annual mean temperature and annual mean salinity were $17.4^{\circ}C$ and 34.06 psu, respectively, showing lower temperature-higher salinity in winter and higher temperature-lower salinity in summer, which means such conditions are inadequate for coral reef formation. Nutrient concentrations represent that total nitrogen ranged from $0.07{\sim}10.08\;{\mu}M$, phosphate from $0.05{\sim}1.70\;{\mu}M$, and silicate from $3.08{\sim}21.86\;{\mu}M$. The N/P ratio showed the range of 9.59-10.60 with decreasing offshore-ward, which means the phytoplankton community could be limited by nitrogen sources. Annual mean euphotic depth was 32.0m (18.9m-48.6m) with difference according to season and reveals the close relationship with the depth of coral distribution. Chlorophyll a concentrations of phytoplankton ranged from $0.12{\sim}1.51\;{\mu}g\;L^{-1}$ and standing crops from $1.5{\times}10^3{\sim}7.0{\times}10^5\;cells\;L^{-1}$, showing higher at inshore than at offshore with a blooming in May. A total of 128 species of phytoplankton occurred in all stations, representing 99 spp. of diatoms, 26 spp. of dinoflagellates, 2 spp. of silicoflagellates and 1 sp. of blue-green algae. Diatoms are main taxa in all seasons except for occupying by dinoflagellates in summer. Among dominant species, fParalia sulcata (Ehrenberg) Cleve and Cylindrotheca closterium (Ehrenberg) Lewin & Reimann were predominant and are likely to be main food sources for coral community. Annual mean species diversity index (H') was 1.84, showing lower than around the coast line of Cheju Island.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.39 no.4
• /
• pp.347-357
• /
• 2003

This paper describes on the suppression of sea clutter on marine radar display using a cell-averaging CFAR(constant false alarm rate) technique, and on the analysis of radar echo signal data in relation to the estimation of ARPA functions and the detection of the shadow effect in clutter returns. The echo signal was measured using a X -band radar, that is located on the Pukyong National University, with a horizontal beamwidth of $$3.9^{\circ}$$, a vertical beamwidth of $20^{\circ}$, pulsewidth of $0.8 {\mu}s$ and a transmitted peak power of 4 ㎾ The suppression performance of sea clutter was investigated for the probability of false alarm between $l0-^0.25;and; 10^-1.0$. Also the performance of cell averaging CFAR was compared with that of ideal fixed threshold. The motion vectors and trajectory of ships was extracted and the shadow effect in clutter returns was analyzed. The results obtained are summarized as follows；1. The ARPA plotting results and motion vectors for acquired targets extracted by analyzing the echo signal data were displayed on the PC based radar system and the continuous trajectory of ships was tracked in real time. 2. To suppress the sea clutter under noisy environment, a cell averaging CFAR processor having total CFAR window of 47 samples(20+20 reference cells, 3+3 guard cells and the cell under test) was designed. On a particular data set acquired at Suyong Man, Busan, Korea, when the probability of false alarm applied to the designed cell averaging CFAR processor was 10$^{-0}$.75/ the suppression performance of radar clutter was significantly improved. The results obtained suggest that the designed cell averaging CFAR processor was very effective in uniform clutter environments. 3. It is concluded that the cell averaging CF AR may be able to give a considerable improvement in suppression performance of uniform sea clutter compared to the ideal fixed threshold. 4. The effective height of target, that was estimated by analyzing the shadow effect in clutter returns for a number of range bins behind the target as seen from the radar antenna, was approximately 1.2 m and the information for this height can be used to extract the shape parameter of tracked target..

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.6
• /
• pp.669-676
• /
• 2017

To understand the relationship between environmental factors and phytoplankton community structures and why early outbreaks of Cochlodinium polykrikoides occur in the inner bay of Korea, short-term investigations were conducted at 17 stations in the eastern part of the South Sea of Korea, with sessions every two weeks from July 7 to August 24, 2016. The water temperature increased from $22.3^{\circ}C$ in the first survey to $28.4^{\circ}C$ in the fourth survey, which was a rise of about $6.01^{\circ}C$. Salinity was relatively high at Stns. 8 13 in the inner bay. In the first survey, rainfall of about 150 mm was observed, so nutrients were supplied at a high level and a high concentrate of Chl. a was observed. Cryptophyta (Crpytomonas spp.) represented 58.3 % of the community, followed by Bacillariophyta at 33.8 %. In particular, at Stn. 5, Dinophyta Prorocentrum spp. accounted for a very high percentage, 32.2 %. In the second survey, low phytoplankton populations were observed, and Bacillariophyta (Chaetoceros spp.) accounted for 61.0 %. At Stn. 4, Skeletonema spp. showed high populations but did not appear at other stations even at a low density. In the third and fourth surveys, phytoplankton populations were very low. Bacillariophyta represented 78.0 % in the third study and 73.3 % in the fourth. Interestingly, although the appearance of C. polykrikoides was investigated at the beginning of the red tide in the coastal area, they were not observed inshore, implying that the likelihood of inflow by the germination of resting cysts was low for the inner bay during this study period. In addition, environmental characteristics such as salinity and nutrient presence were significantly different between sampling stations due to the existence of a semi-closed bay in the southern sea, resulting in dominant phytoplankton species and community composition differing in these short-term investigations.

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