• Economic and Environmental Geology
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• v.50 no.2
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• pp.129-143
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• 2017

The shallow sediments in the southwestern Ulleung Basin consist of mass flow deposits such as slide/slump and debris flow deposits (DFD), caused by slope failure. These sediments are proven to be important in studying geological disaster and stability of the seafloor. In this paper, we analysised the flow accumulation and slope failure susceptibility of the Ulleung Basin on the basis of multi-beam data, collected in this area. We also studied the distribution pattern and the seismic characteristics of the DFD in the uppermost layer of the Ulleung Basin on the basis of seismic data. The slope susceptibility was calculated as the frequency ratio of each factors including slope, aspect, curvature and stream power index (SPI), which causes the slope failure. These results indicate that the slope failure is frequently to occur in the southern and western continental slope of the Ulleung Basin. The sediment flow (mass flow) caused by the slope failure converges to the north and northwest of the Ulleung Basin. According to the seismic characteristics, the uppermost layer in study area can be divided into four sedimentary unit. These sedimentary units develop from the south and southwest to the north and northwest in association with slope susceptibility and flow accumulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.189-195
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• 2001

The characteristics of echolocation signals of the Common Dolphin, Delphinus Delphis was observed by the hydrophone in order to detect exactly distribution and migration on whales and dolphins in Korean Coastal waters. It's observation was carried out at the position of 13 mm off Gam-Po of Korean east-southern sea at 3rd-5th. April and 13th-15th. October, 1999. The results obtained are summarized as follows: (1) The frequency range of ship's noise and ambient noise in the observed station was 0.5-0.3 kHz, that ones could be influenced to the behavior of common dolphins which carry out echolocation using low-frequency. (2) The common dolphin was radiated single click of 8.6 ms and double click of 4.8 ms pulse width during these observation (3) The high click frequencies of common dolphin were 5.10 kHz, 7.22 kHz, 10.60 kHz with the click pulse width of 4.0 ms, 2.6 ms, 1.0 ms, respectively. In case of low-frequency 1-2 kHz, that is, 1.12 kHz, 1.38 kHz, 1.82 kHz, pulse width were 22.4 ms, 2.05 ms, 11.9 ms, respectively and they showed a tendency using triple click signal. (4) The pulse width, pulse recurrence interval and frequency range of the observed echolocation signals were 2.4-8.4 ms, 9.0-40.0 ms, 0.60-10.63 kHz respectively, and frequency spectrum level was 100-125 dB for single, double, triple click signals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.296-301
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• 1998

The physical and chemical characteristics were examined in the southern sea of Korea including the Cheju Strait, and the entrance of the Korea Strait in the period of May 30 to June 8, 1995. The results are as follows. Firstly, the variation ranges of the temperature and salinity at the Cheju Stratit during 24 hours observation were larger in the surface layer than that in the deep layers. Secondly, daily variations of nutrients show that total inorganic nitrogen, phosphate phosphorous, and silicate silicon concentration are higher at night than at day. Thirdly, water temperature and salinity distributions show highest values at the entrance of Korea Strait, which is thought to be influenced directly by Tsushima Warm Current, while they show the lowest values in Cheju Strait. This means that the surface waters in Korea Strait are greatly influenced from the entrance of Korea Strait and bottom waters is greatly influenced from Cheju Strait. Fourthly, nutrients distribution shows highest values in Korea Strait but dissolved oxygen shows lowest values in the area. These seem to be caused by the oxygen consumption used in the inorganization of nutrients to decompose organisms and the liquidation of nutrients.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1509-1518
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• 2013

An agar-degrading bacterium, designated as strain $G7^T$, was isolated from a coastal seawater sample from Gaya Island (Gayado in Korean), Republic of Korea. The isolated strain $G7^T$ is gram-negative, rod shaped, aerobic, non-motile, and non-pigmented. A similarity search based on its 16S rRNA gene sequence revealed that it shares 95.5%, 90.6%, and 90.0% similarity with the 16S rRNA gene sequences of Catenovulum agarivorans $YM01^T$, Algicola sagamiensis, and Bowmanella pacifica W3-$3A^T$, respectively. Phylogenetic analyses demonstrated that strain $G7^T$ formed a distinct monophyletic clade closely related to species of the family Alteromonadaceae in the Alteromonas-like Gammaproteobacteria. The G+C content of strain $G7^T$ was 41.12 mol%. The DNA-DNA hybridization value between strain $G7^T$ and the phylogenetically closest strain $YM01^T$ was 19.63%. The genomes of $G7^T$ and $YM01^T$ had an average ANIb value of 70.00%. The predominant isoprenoid quinone of this particular strain was ubiquinone-8, whereas that of C. agarivorans $YM01^T$ was menaquinone-7. The major fatty acids of strain $G7^T$ were Iso-$C_{15:0}$ (41.47%), Anteiso-$C_{15:0}$ (22.99%), and $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$ (8.85%), which were quite different from those of $YM01^T$. Comparison of the phenotypic characteristics related to carbon utilization, enzyme production, and susceptibility to antibiotics also demonstrated that strain $G7^T$ is distinct from C. agarivorans $YM01^T$. Based on its phenotypic, chemotaxonomic, and phylogenetic distinctiveness, strain $G7^T$ was considered a novel genus and species in the Gammaproteobacteria, for which the name Gayadomonas joobiniege gen. nov. sp. nov. (ATCC BAA-2321 = $DSM25250^T=KCTC23721^T$) is proposed.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.481-485
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• 2005

The port entry system of the inner harbor in Pyeongtaek${\cdot}$Dangjin was planned as lock-gate in 'Master plan project on port planning in Asan industry base(1990)‘, but was changed to tidal harbor in 'Project maintaining Master plan for comprehensive development of Pyeongtaek${\cdot}$Dangjin port(2001)'. Accordingly, southern sea bank constructed under the lower part of Seohae-bridge will be removed so that inbound/outbound vessels for the inner harbor can navigate at all times. However, in the view of the safety on passing through the lower of Seohae-bridge, navigating conditions for the inner harbor will be restricted in the single-way of 50,000 DWT vessel and the two-way of vessel less than 30,000 DWT Therefore, this study carried out the estimation of traffic congestion arising from these vessels with above restrictions q[ter supposing annual inbound/outbound vessel's numbers for loading and unloading cargo surveyed on the inner harbor.

• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.238-248
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• 2010

We performed field investigations at six stations in Buk Stream of Goseong-gun, Gangwon-do, Korea, from May to September 2009 to understand the stream's fish fauna and community structure. In the survey, 31 species belonging to 20 families were collected. Dominant species by number was Zacoo koreanus (30.0%), and subdominant species were Pungitius kaibarae (9.4%) and Rhynchocypris steindachneri (9.3%). In biomass, the dominant species was Tribolodon hakonensis (35.5%), and subdominant species were Z. koreanus (22.5%) and Cobitis pacifica (7.5%). Eight Korean endemic fish species and two endangered species (P. kaibarae and Pungitius sinensis) were collected. In addition, four anadromous fish species (T. hakonensis, Oncorhynchus masou masou, O. keta, Gasterosteus aculeatus) and two amphidromus fish species (Plecoglossus altivelis altivelis and Gymnogobius urotaenia) were observed. Interestingly, we verified the existence of several fish species in Buk Stream where they have not lived before. Those species were previously reported to live only in rivers that run into the western and southern sea of Korea. Five of those species (Zacoo koreanus, Z. platypus, Silurus microdorsalis, Liobagrus andersoni and Coreoperca herzi) were reported in Buk Stream in the 1980s. The other species (Pungtungia herzi, Pseudorasbora parva, Squalidus multimaculatus, Misgurnus mizolepis, Koreocobitis rotundicaudata, Silurus asotus and Odontobutis interrupta) have been introduced since the 1990s.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.354-369
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• 2010

The synoptic and kinematic characteristics of a heavy rainfall that occurred in Gangneung region on 22 to 24 October 2006 were investigated using weather maps, infrared images, AWS observation data and NCEP global final analyses data. The total amount of rainfall observed in the region for the period was 316.5 mm, and the instanteneous maximum wind speed was $63.7m\;s^{-1}$. According to the analysis of weather maps, before the starting of the heavy rainfall, an extratropical low pressure system was developed in the middle region of the Korean Peninsula, and an inverted trough was formed in the northern region of the peninsula. In addition, a jet stream on the upper charts of 300 hPa was located over the Yellow Sea and the southern boundary of the peninsula. A cutoff low in the cyclonic shear side of the upper jet streak, which was linked to an anomaly of isentropic potential vorticity, was developed over the northwestern part of the peninsula. And there are analyzed potential vorticity and wind, time-height cross section of potential vorticity, vertical air motion, maximums of the divergence and convergence and vertical distribution of potential temperature in Gangneung region. The analyzed results of the synoptic conditions and kinematic processes strongly suggest that the tropopause folding made a significant role of initializing the heavy rainfall.

• Journal of the Korean earth science society
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• v.34 no.7
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• pp.645-661
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• 2013

The synoptic, thermodynamic, and dynamic characteristics of a heavy snowfall event that occurred in Seoul metropolitan area on 27 to 28 December 2010 was investigated. During this period there was a distinctive case that was identified as a polar low. We analyzed surface and upper level weather charts, snowfall amount, sea surface temperature, satellite imagery, sounding, and the National Center for Environmental Prediction global $1^{\circ}{\times}1^{\circ}$ reanalysis data. The polar low developed in an area where there was strong baroclinicity in the lower level aided by strong conditional instability due to 925 hPa warm air advection and 700 hPa cold air advection. The development mechanism of polar low is due, in part, to the tropopause folding, which advected stratospheric air increasing potential vorticity in mid-level and inducing cyclonic vorticity and convergence in low-level. Eventually clouds developed and there were snowfall total of 10 cm in Seoul metropolitan area and as much as 20 cm in southern parts of Korea. During the snowfall development, there was a $-45^{\circ}C$ cold core at 500 hPa and shortwave maintained $3-5^{\circ}$ separation with surface trough, which favored the development of polar low located in the warm sector and cyclonic advection area. The height of the dynamical tropopause lowered to 700 hPa during the peak development and increase in potential vorticity allowed strong vertical motion to occur. Overall, there was a close relationship between the development of snowfall and tropopause undulation. The heaviest snowfall occurred east of the tropopause folding where strong cyclonic vorticity, vertical motion, and moisture advection all coincided while the polar low was passing through the Korean peninsula.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.191-195
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• 2005

The port entry system of the inner harbor in Pyeongtaek (Asan) was planned as lock-gate in 'Master plan project on port planning in Asan industry base(1990)', but was changed to tidal harbor in 'Project maintaining Master Plan for comprehensive development of Pyeongtaek (Asan) port(2001)'. Accordingly, southern sea bank constructed under the lower part of Seohae-bridge will be removed so that inbound/outbound vessels for the inner harbor can navigate at all times. However, in the view of the safety on passing through the lower of Seohae-bridge, navigating conditions for the inner harbor will be restricted in the single-way of 50,000 DWT vessel and the two-day of vessel less than 30,000 DWT. Therefore, this study carried out the estimation of traffic congestion arising from these vessels with above restrictions after supposing annual inbound/outboubd vessel's numbers for loading and unloading cargo surveyed on the inner harbor.

• Korean Journal of Ichthyology
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• v.28 no.3
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• pp.164-174
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• 2016

Tanakius kitaharae and Glyptocephalus stelleri, belonging to the family Pleuronectidae, were very similar in external morphology not only during adult periods, but also during larval periods. In this study, we compared larval development and growth of the two pleuronectids species in detail. Fifty-eight specimens of T. kitaharae larvae and five specimens of G. stelleri larvae were collected from the East Sea, southern Korean Strait, and the adjacent waters of Jeju Island during 2014~2016, and were identified using morphological and molecular markers. Flexion larvae of T. kitaharae (10.23~16.77 mm total length, TL) and G. stelleri (14.33 mm TL) were similar in morphometrics, but can be distinguished by the melanophores in the fin membranes (present in the former vs. absent in the latter), and the melanophores at posterior margin of shoulder girdle (absent in the former vs. present in the latter). Postflexion larvae of T. kitaharae (17.12~24.92 mm TL) and G. stelleri (27.71~32.95 mm TL) differed in the number of melanophores on the mid-lateral caudal region (two in the former vs. five in the latter), and that on the dorsal and anal fin pterygiophores (five or six in the former vs. one row in the latter). Tanakius kitaharae and G. stelleri larvae differed in size at the beginning of metamorphosis. The left eye of T. kitaharae larvae between 23.13~24.92 mm TL reached the dorsal margin of the head while that of G. stelleri larvae between 38.66~42.67 mm TL did not reached yet.