• Atmosphere
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• v.24 no.2
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• pp.189-196
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• 2014

The definition of onset date of Changma is revisited in this study using a quality controlled Ieodo ocean research station data. The Ieodo station has great importance in terms of its southwest location from Korean Peninsula and, hence, makes it possible to predict Changma period in advance with less impact of continents. The onset date of Changma using the Ieodo station data is defined by the time that meridional wind direction changes and maintains from northerly to southerly, and then the zonal wind changes from easterly to westerly after first June. This definition comes from a recognition that the establishment and movement of the western North Pacific subtropical high (WNPSH) cause Changma through southwesterly flow. The onset data of Changma has been determined by large-scale dynamic-thermodynamic characteristics or various meteorological station data. However, even the definition based on circulation data at the Ieodo station has a potential for the improved prediction skill of the onset date of Changma. The differences between before and after Changma, defined as Ieodo station data, are also found in synoptic chart. The convective instability and conspicuous circulations, corresponding low-level southwesterly flow related to WNPSH and strong upper-level zonal wind, are represented during Changma.

• Ocean and Polar Research
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• v.27 no.4
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• pp.397-417
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• 2005

Phytoplankton community structure and distribution pattern in the surface water around the Ieodo Ocean Research Station were investigated during seven cruises carried out from July, 2003 to October, 2004. Samples were analyzed using various tools including a microscope, flow cytometer, and HPLC. Satellite images were used to analyze spatio-temporal phytoplankton biomass distribution. SeaWiFS chlorophyll a (chl a) images showed that spring blooms occurred in April-May near the Ieodo Station, and these waters were under the influence of Changjiang Dilute Water during July-October. Also, during the July-October period, HPLC pigments data showed increasing zeaxanthin concentrations, a marker pigment of cyanobacteria whereas increasing concentrations of various other pigments such as fucoxanthin, peridinin, prasinoxanthia alloxanthin, 19'-hexanoyloxyfucoxanthin and chlorophyll b were noted during spring blooms. Such pigment marker data were consistent with picoplankton data analyzed by flow cytometer and nano-microplankton analyzed by microscope. The pigment-CHEMTAX method was used to drive the phytoplankton group apportioned chi a. Diatoms, chlorophytes, dinoflagellates, and cryptophytes comprised 25.8, 20.7, 15.9, and 14.1%, respectively, of the total chl a in May. Average cyanobacteria concentrations in July-October contributed 25.4% of the total concentration. This was the highest percent contribution and was followed by chlorophytes, diatoms, and prymnesiophytes. This study discusses results from various methods, similarities and differences in the results among those methods, and the application range of the results from different analytical methods. Also, the study reveals a detailed phytolpankton community structure in the waters around the Ieodo Station, and suggests future monitoring considerations in relation to cell morphology, ecology and diversity factors according to taxonomic groups.

• Ocean Science Journal
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• v.41 no.3
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• pp.175-179
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• 2006

The Ieodo Ocean Research Station(IORS) is an integrated meteorological and oceanographic observation base which was constructed on the Ieodo underwater rock located at a distance of about 150 km to the south-west of the Mara-do, the southernmost island in Korea. The underwater ambient noise level observed at the IORS was similar to the results of the shallow water surrounding the Korean Peninsula (Choi et al. 2003) and was higher than that of deep ocean (Wenz 1962). The wind dependence of ambient noise was dominant at frequencies of a few kHz. The surface current dependence of ambient noise showed good correlation with the ambient noise in the frequency of 10 kHz. Especially, the shrimp sound was estimated through investigations of waveform and spectrum and its main acoustic energy was about 40 dB larger than ambient noise level at 5 kHz.

• Ocean and Polar Research
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• v.32 no.4
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• pp.427-437
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• 2010

The Korean Government is trying to construct an ocean research station in Dokdo's water. The station would be the third ocean research station following the Ieodo station and the Gageocho station. Although the new station would served as a scientific research base for peaceful and academic purposes, the construction of the station will almost certainly lead to a diplomatic dispute between Japan and Korea in the near future due to the disputed ownership of the island. In light of the diplomatic protests against the construction of the Ieodo station by the Chinese Government, various domestic and international legal issues which could be raised regarding the construction of the Dokdo station need to be reviewed. Therefore, this article reviews the international legal status of the station and the rights and duties pertaining to its construction, investigates the domestic legal grounds relating to the construction and operation of the marine scientific installation, evaluates the international legal impacts of the construction on the expansion of maritime jurisdiction, the effective control on Dokdo and the negotiations on maritime boundary delimitation, and finally draws conclusions on the future activities of the Korean Government for the construction and operation of the Dokdo Ocean Research Station.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.6
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• pp.537-546
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• 2015

This paper deals with the retrieval of integrated water vapor (IWV) from the zenith tropospheric delay estimated by precisely processing GPS observations at IEODO ocean research station in the East China Sea. A comparison of GPS-IWV with the radiosonde profiling from June and November in 2014 was made to confirm the method and the procedure, adopted for the IWV determination. A series of analysis of these IWV values was performed to capture characteristics of their seasonal and diurnal variations. Furthermore, the troposphere around the ocean research station during typhoon events was spatiotemporally analyzed by including thirteen GPS sites over the Korean Peninsula, indicating correlation between the typhoon location and the tropospheric density.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.225-234
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• 2006

Using the data from the sea water monitoring system installed at the Ieodo Ocean Research Station, we have analyzed the water properties around the station as well as the characteristics of the fresh water from the Changjiang River and the influence of typhoons on the sea water. In general, the accuracy and stability of the temperature data are high, but those of the salinity data are worse than the specification of the instruments. The daily variation of temperature and salinity is mainly controlled by the vertical motion of a water column due to semi-diurnal tide and diurnal change in the solar insolation. Seasonal change is prominent in temperature data. The freshwater from the Changjiang River is the main cause of large salinity variation. In August 2003 and August 2004, about 10 days before fresh water was observed near the Jeju Island, low salinity water was observed at the Ieodo Station. On the other hand, in July 2005 fresh water was observed at the station but not at around the Jeju Island. In other words, the fresh water observed at the Ieodo Station does not always expand to the Jeju Island. Two strong typhoons passed by the station in September 2003 and August 2004. The effects of the typhoons were lasted for 3 to 4 days.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.476-483
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• 2007

One of the main function of Ieodo Ocean Research Station is to service the information about the weather and fishing grounds condition which are collected through calibrating convection flow and ocean current around the station. However, due to the influence of the station's structure below sea level, it is difficult to obtain the exact flow data. Therefore, it is required to research on the effect of the structure and the method to evaluate and revise the observed data. In this paper, as a basic study, it deals with the algorithm that simulate the interaction between ocean current and the station structure, followed by discussions about the way to applicate the algorithm. Through 3-dimensional computational fluid dynamics analyses (using Navier-Stokes equations with K-turbulence model), the influence of the station and submerged rocks are quantitatively evaluated, and we would suggest methods how to obtain accurate flow information from the measured rough data.

• Korean Journal of Remote Sensing
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• v.21 no.2
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• pp.113-120
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• 2005

Oceanographic measurements from Ieodo Ocean Research Station and its vicinity were compared for assessment and mutually adjusted with satellite data. From the Topex/Poseidon and ERS-1/2 radar altimeter and scatterometer data, sea surface height, wind speed and direction were extracted and analyzed. Shipborne wind direction data acquired in June 1995 show good coherence with the satellite data, while sea surface height and wind speed show differences, possibly resulting from the distance between the measurement points. This can be improved by analyzing more satellite data or using other available shipborne data. The recent 3 months of Ieodo Station data between December 2004 and February 2005 were also analyzed and compared with the satellite data. The Ieodo Station data were found to have considerable gaps during the period as well as seriously biased particular when the data were averaged with some abnormal data. The Ieodo Station and satellite data were then mutually adjusted on the basis of their statistics. Ieodo Station oceanographic measurements are very efficient for ground-frothing of satellite data because they are stationary and the station is located far from the coast. On the other hand, the satellite measurements are the only data to fill up gaps and adjust biases of the Ieodo Station data.

• Ocean and Polar Research
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• v.25 no.spc3
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• pp.373-384
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• 2003

When pile foundation is constructed by dynamic method, it is desirable to perform monitoring of drivability with pile penetration. Dynamic pile monitoring yields information regarding driving hammer, cushion, pile and soil behaviour that can be used to confirm the assumptions of wave equation analysis. In this study, dynamic monitoring of the steel pipe pile was performed with Pile Driving Analyser (PDA). The PDA utilizes the wave propagation theory to compute numerous variables which describe the conditions of the hammer-pile-soil system in real-time and following each hammer impact. This approach allows immediate field verification of hammer performance, driving efficiency, and estimation of pile bearing capacity. A series of PDA test were performed at the Ieodo Ocean Research Station (IORS) located in southeast of Marado, a southernmost small island south of Jeju Island. The drilling core sediments of Ieodo subsoil are composed of mud and sand, showing lamination and wavy or lenticular bedding, which were often bioturbated. This paper summarizes the results of PDA tests which were applied in measurement and estimation of large diameter open ended steel pipe pile driven by steam hammer, Vulcan-560 and MRBS-4600, at the marine sediments.

• Ocean Science Journal
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• v.41 no.4
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• pp.315-318
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• 2006

Three Synechococcus strains were isolated from seawater near the Ieodo Ocean Research Station (IORS), and their 16S rDNA genes and the internal transcribed spacer (ITS) between the 16S and 23S rRNA genes were sequenced to investigate their phylogenetic relationships. Phylogenetic trees based on the 16S rDNA and ITS sequences showed that they clustered in the main MC-A Synechococcus group (subcluster 5.1), but formed branches differentiating them from the described clades. As the IORS is located in an area affected by diverse water masses, high Synechococcus diversity is expected in the area. Therefore, the IORS might be a good site to study the diversity, physiology, and distribution of the Synechococcus group.