• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.58-60
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• 2020

겨울철 온대저기압은 그 세력이 강하여 해양사고의 주요 원인이 되는 등 선박의 안전 운항에 있어서 매우 중요하다. 이 연구에서는 겨울철(2019년 12월~2020년 2월)의 기상 데이터를 이용하여 제1태평양 한대전선대 부근의 온대저기압에 대하여 분석하였다. 분석 결과는 다음과 같다. 3개월 동안에 제1태평양 한대전선대 부근에서 발생한 온대저기압은 41개이고, 그 중 8개가 현저히 발달하였다. 발생 위치 별 온대저기압은 일본 동쪽 태평양이 가장 많았고(16개), 그 다음은 우리나라 주변, 동중국해, 일본 남쪽 해상 순이었다. 이동경로는 크게 5개로 구분할 수 있는데, 공통적으로 북동진하는 패턴을 보였다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.140-146
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• 1996

동해는 Korea Strait, Tsugaru Strait Soya Strait, Mamiya Strait의 좁은 해협으로 동중국해의 북동해역, 태평양 및 Okhotsk 해로 연결되나, 해협부의 폭과 수심이 작아 폐쇄된 해역으로 볼 수 있다. 동해에 대한 조석현상을 파악하기 위해서는 Ogura(1933)와 Nishida(1980)의 한국 주변해역(동아시아)에 대한 경험적인 조석도를 참고할 수 있으며, Odamaki(1989a)는 대한해협에서의 자료를 재편집하여 개선된 조석도를 제시하였다. (중략)

• 한국해양학회지
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• v.22 no.3
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• pp.119-129
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• 1987

Sediments in the cores from the KONOD-1 area consist mainly of authigenic smectite and clinoptilolite, and terrigenous minerals of illite, chlorite, kaolinite, quartz, and plagioclase. The authigenic minerals become dominant over the terrigenous minerals with increasing depth. Clinoptilolite occurs at the deeper core depth because its formation is slower than that of smectite. The vertical distribution of minerals indicates that the eolian influence, probably in the late Oligocene, diluted the abundance if smectite in near-surface sediments. This vertical distribution pattern may also have been affected by progressive dissolution of authigenic minerals in the near surface sediments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.142-148
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• 1998

Environmental baseline information is necessary in order to assess the potential environmental impact of future manganese-nodule mining on the deep-seabed ecosystem. Total ATP (T-ATP), dissolved ATP (D-ATP) and particulate ATP (P-ATP) were measured to estimate total microbial biomass and to elucidate their vertical distribution patterns in the seabed of KODOS (Korea Deep Ocean Study) area, northeast equatorial Pacific Ocean. Within the upper 6 cm depth of sediment, the concentrations of T-ATP, D-ATP and P-ATP ranged from 4.4 to 40.6, from 0.6 to 16.1, and from 3.0 to 29.2 ng/g dry sediment, respectively. Approximately 84% of T-ATP, 81% of D-ATP, and 74% of P-ATP were present within the topmost 2 cm depth of sediment, and the distributions of ATP were well correlated with water content in the sediment. These results indicate that the distribution of total microbial biomass was largely determined by the supply of organic matter from surface water column. Fine-scale vertical variations of ATP were detected within 1-cm thick veneer of the sediment samples collected by multiple corer, while no apparent vertical changes were observed in the box-cored samples. It is evident that the box-core samples were disturbed extensively during sampling, which suggests that the multiple corer is a more appropriate sampling gear for measuring fine-scale vertical distribution pattern of ATP within thin sediment veneer. Overall results suggest that the concentrations of ATP, given their clear changes in vertical distribution pattern within 6 cm depth of sediment, are a suitable environmental baseline parameter in evaluating the variations of benthic microbial biomass that are likely to be caused by deep-seabed mining operation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.2
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• pp.73-79
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• 1996

This study was conducted to investigate the faunal composition and distribution patterns of macrobenthic community in the deep sea sediments of the KODOS area, the northeastern Pacific Ocean during May 1996. Benthic animals were collected at 25 stations using a spade type box corer. Sediments were sieved through -.3 mm mesh screen. A total of 17 faunal groups in 9 phyla and 363 specimens were identified. Nematoda was the most abundant faunal group which accounted for 30.0% of total abundance. Other dominant faunal groups were foraminiferans (25.1%), harpacticoids (10.2%), xenophyophores (5.2%), and polychaetes (4.7%), Polychaeta was a typically dominant component of macrobenthic community in the study area except traditionally recognized meiofauna taxa. Mean occurrence number of faunal taxa was ca. 6 per 0.01 m$\^$2/, and mean density was estimated as 1,288 indiv./m$\^$2/. The abundance of whole fauna and that of each faunal group was highest at the surface layer of sediment, and decreased monotonously along the sediment depth; 98% of faunal abundance was found within 10 cm depth layer.

• Ocean and Polar Research
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• v.27 no.1
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• pp.1-13
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• 2005

The samples for organic carbon analysis were collected between $5^{\circ}\;and\;17^{\circ}N$ along $131.5^{\circ}W$ in the northeast Pacific KODOS (Korea Deep Ocean Study) area. The mean concentration of total organic carbon (TOC) in the surface mixed layer $({\sim}50 m)$ was $100.13{\pm}2.05{\mu}M-C$, while the mean concentration of TOC in the lower 500m of the water column was $50.19{\pm}4.23{\mu}M-C$. A strong linear regression between TOC and temperature $(r^2=0.70)$ showed that TOC distribution was controlled by physical process. Results from the linear regression between chlorophyll-a and TOC, and between chlorophyll-a and particulate organic carbon (POC), decreasing of dissolved organic carbon (DOC) in the surface layer caused by non-biological photo-oxidation process. Below the surface layer, biological production and consumption occurred. DOC accumulation dominated in the depth range of $30{\sim}50m$ and DOC consumption occurred in the depth range of $50{\sim}200m$. TOC was inversely correlated with apparent oxygen utilization (AOU) and TOC/AOU molar ratios ranged from -0.077 to -0.21. These ratios indicated that TOC oxidation was responsible fur $10.9{\sim}30.1%$ (mean 20.2%) of oxygen consumption in the NE Pacific KODOS area. In the euphotic zone, distributions of dissolved and particulate organic matter were controlled by photo-chemical, chemical, biological and physical processes.

• 한국해양학회지
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• v.26 no.1
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• pp.1-12
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• 1991

A multi-disciplinary geophysical study including gravity, magnetic, and seismic reflection profiling was carried out in the area between the Clarion fracture zone and the Clippertone fracture zone o the northeastern equatorial Pacific basin. There are small free-air gravity anomalies of less than 20 mgal over seamounts and the east-west trending abyssal hills. The negative residual gravity anomalies over seamounts may indicate the existence of low density seamount roots compared to surrounding oceanic crust. Non-existence of magnetic lineations and the magnetic anomalies of small smplitude with no polarity change in the east-west direction support that the study area belongs to the Cretaceous magnetic quite zone. Positive magnetic anomalies over seamounts offset 100 km in the east-west direction in the southern part of the study area suggest a possibility of left-lateral movement of those seamounts along unknown fractures. The sedimentary section in the study area can be divided into three units (Unit I, unit IIA, and Unit IIB) n the basis of reflection characteristics. the total thickness of sedimentary section varies from 200 to 400 meters and the sedimentary section is thicker in the southern area of rough topography near the seamount belt than in the northern flat area. Manganese nodules are abundant in the southern part of the study area where the ridges are developed and the Unit I layer is thicker than 100 meters.

• Journal of Navigation and Port Research
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• v.44 no.6
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• pp.447-452
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• 2020

Extratropical cyclone in winter season is very important in safe operation of ships because it is a major cause of marine accidents due to its strong power. In this study, we used meteorological data, to analyze extratropical cyclones occurring near the 1st Pacific polar front from December 2019 to February 2020. The analysis results are as follows. During those three months, we recorded 41 extratropical cyclones, 8 of which were remarkably developed. The central pressure of the strongest cyclone was 947hPa. The highest number of cyclones were generated in the East P acific Ocean around J apan (16), followed by the areas around Korea, the East China Sea, and the southern Sea of J apan. The cyclones followed five major tracks with a common northeast pattern. We thus concluded that the optimal route for a ship encountering an extratropical cyclone in the North P acific in winter would be south of the cyclone's center traveling eastbound and north of the center traveling westbound.

• Economic and Environmental Geology
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• v.45 no.5
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• pp.477-486
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• 2012

High-resolution bathymetry and physico-chemical properties of manganese nodules were explored to identify the relationship between morphological features and nodule occurrences in the KR1, one of the Korean contract nodule fields located in the NE Pacific. The high-resolution seabed mapping showed that the southwestern sector of the KR1 (KR1-1) was relatively deeper than the northeastern sector (KR1-2) which is occupied by small-scale seamounts. In terms of nodule occurrence, manganese nodules in the KR1-1 were comparatively larger (2-4 cm) with rough surface (t-type) and discoidal shapes (D-type), while those in the KR1-2 were generally small (<2 cm) with smooth surface (s-type) and irregular shapes (I-type). In addition, the nodules in the KR1-1 had higher contents of Cu, Mn and Ni. Such connections of water depths to nodule appearances and metal contents are commonly observed in the Pacific nodule fields. On the other hand, the nodules in the KR1-2 tend to be controled by morphological features. The seamounts in the KR1-2 might continuously provide rock fragments as new nuclei of manganese nodules. As a result, the nodules could not grow over than 2 cm and showed the shapes of a newbie (i.e., smooth surface and irregular shapes). As a result, our observations indicate that occurrence features of manganese nodules could be subjected to water depths and seabed morphology simultaneously.

• The Journal of the Petrological Society of Korea
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• v.21 no.3
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• pp.367-383
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• 2012

The Gyeongsang Arc is the most notable of the Korea Arc that is composed of several volcanic arcs trending to NE-SW direction in the Korean peninsula. The Hayang Group has many volcanogenic interbeds of lava flows by alkaline or calc-alkaline basaltic volcanisms during early Cretaceous. Late Cretaceous calc-alkaline andesitic and rhyolitic volcanisms reconstructed the Gyeongsang Arc that consist of thick volcanic strata on the Hayang Group in The Gyeongsang Basin. The volcanisms characterize first eruptions of basaltic and andesitic lavas with small pyroclastics, and continue later eruptions of dacitic and rhyolitic ash-fall and voluminous ash-flow with some calderas and then domes and dykes. During the Early Cretaceous (about 120 Ma), oblique subduction of the Izanagi plate to NNW from N direction results in sinistral strike-slip faults to open a pull-apart basin in back-arc area of the Gyeongsang Arc, in which erupted lava flows from generation of magma by a decrease in lithostatic pressure. Therefore the Gyeongsang Basin is interpreted into back-arc basin reconstructed by a continental rifting. Arc volcanism began in about 100 Ma with exaggeration of the back-arc basin in the Gyeongsang, and then changed violently to construct volcanic arcs. During the Late Cretaceous (about 90 Ma), orthogonal subduction of the Izanagi plate to NW from NNW direction ceased development of the basin to prolong violent volcanisms.