• Ocean and Polar Research
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• 제30권3호
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• pp.277-287
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• 2008

We collected information on seasonal and interannual variability of surface chlorophyll a concentration between 1997-2007 from the Northwest Pacific Ocean. Satellite data were used to acquire chlorophyll a and sea surface temperature from six regions: East Sea/Ulleung Basin, East China Sea, Philippin Sea, Warm Pool region, Warm Pool North region, and Warm Pool East region. Mixed layer depth (MLD) was calculated from temperature profiles of ARGO floats data in four of the six regions during 2002-2007. In the East Sea/Ulleung Basin, seasonal variability of chlorophyll a concentration was attributed to seasonal change of MLD, while there was no significant relationship between chlorophyll a concentration and MLD in the Warm Pool region. Interannual anomaly in sea surface temperature were similar among the East Sea, East China Sea, Philippin Sea, and Warm Pool North region. The anomaly pattern was reversed in the Warm Pool East region. However, the anomaly pattern in the Warm Pool region was intermediate of the two patterns. In relation to chlorophyll a, there was a reversed interannual anomaly pattern between Warm Pool North and Warm Pool East, while the anomaly pattern in the Warm Pool region was similar to that of Warm Pool North except for the El $Ni\tilde{n}o$ years (1997/1998, 2002/2003, 2006/2007). However, there was no distinct relationship among other seas. Interestingly, in the Warm Pool and Warm Pool East regions, sea surface temperature showed a pronounced inverse pattern with chlorophyll a. This indicates a strong interrelationship among sea surface temperature-MLD-chlorophyll a in the regions. In the Warm Pool and Warm Pool East, zonal distribution of chlorophyll a concentration within the past 10 years has shown a good relationship with sea surface temperature which reflects ENSO variability.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.655-655
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• 2002

Spatial distribution of phytoplankton pigment concentration (PPC) and sea surface temperature (SST) around the East Korean Warm Current (EKWC) was described, using both ocean color images and advanced very high resolution radiometer (AVHRR) images. Water mass in this region can be classified into five categories in the horizontal profile of PPC and SST, nLw(normalized water-leaving radiance) images: (1) coastal cold water region associated with concentrations of dissolved organic material or yellow colored substances and suspended sediments, (2) cold water region of thermal frontal occurred by a combination of phytoplankton absorption and suspended materials, (3) warm water overlay region by the phytoplankton absorption than the suspended materials; (4) warm water region occurred by the low phytoplankton absorption, and (5) offshore region occurred by the high phytoplankton absorption. In particular, the highest PPC area appeared in the ocean color and SST images with a band shaped distribution of the thermal front and ocean color front region, which is located the coastal cold waters along western thermal front of the warm streamer of the EKWC.

• Ocean and Polar Research
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• 제30권2호
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• pp.193-205
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• 2008

A model of the current and seasonal volume transport in the East China Sea was used to investigate the origin of the Tsushima Warm Current (TSWC). The modeled volume transport field suggested that the current field west of Kyushu ($30^{\circ}-32^{\circ}N$) was divided into two regions, R1 and R2, according to the bottom depth. R1 consisted of the Taiwan Warm Current (TWWC) region and the mixed Kuroshio-TWWC (MKT) water region, while R2 was the modified Kuroshio water (MKW) region west of Kyushu. The MKW branched from the Kuroshio and flowed into the Korea/Tsushima Straits through the Cheju-Kyushu Strait, contributing 41% of the annual mean volume transport of the TSWC. The TWWC and MKT water flowed into the Korea/Tsushima Straits through the Cheju-Kyushu and Cheju Straits, contributing 32% and 27% of the volume transport, respectively. The maximum volume transport of the MKW was 53% of the total volume transport of the TSWC in November, while the maximum volume transport of the water in the R1 region through the Cheju-Kyushu Strait was 41% in July. Hence, there were two peaks per year of volume transport in the TSWC.

• Fisheries and Aquatic Sciences
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• 제4권3호
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• pp.101-111
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• 2001

In an attempt to demonstrate the seasonal variation of the Ulleung Warm Eddy (UWE), in which the UWE changes its shape from a warm core ring in early spring to a warm lens in late summer under the effect of surrounding East Korean Warm Current (EKWC) Water, a simple geostrophic adjustment model is considered. Model results indicate that the buoyancy increase of the EKWC Water and the strengthening of the EKWC towards summer, both of which are typical of this region, are the major factors governing the seasonal variation of the UWE.

• 한국군사과학기술학회지
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• 제12권4호
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• pp.415-423
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• 2009

To investigate low frequency acoustic transmissions in the Sub-Polar Front(SPF) of the East Sea, numerical experiments are conducted with Range dependent Acoustic Model(RAM) using Circulation Research of the East Asian Marginal Seas(CREAMS) data and Autonomous Profiling Explorer(APEX)) data. Significant seasonal variations of sea water properties are existed across the Sub-Polar Front(SPF) region from the north and the south. The model results show that Transmission Loss(TL) decrease(about 20dB) with ideal front in the warm region whereas TL increase(about 25dB) with ideal front in the cold region. Regardless of season(both in summer and winter), when the sound source is located in the cold region of the SPF, the model results show weak TL, compared to the case of the source in the warm region(Maximum difference of TL reaches 28dB). This difference between the cases when the source is located in the cold region and the warm region, is accounted for from the different vertical profiles of sound speed in both regions.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.103-107
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• 2001

The major studies of an ocean circulation of the East/Japan Sea related to evaluate the feasibility and utilization of deep ocean water are reviewed. The major feature of surface current system of the East/Japan Sea is an inflow of the Tsushima Warm Current through the Korea/Tsushima Strait and the outflow through the Tsugaru and Soya Straits. The Tsushima Warm Current has been known to split into two or three branches in the southern region of the East/Japan Sea. In the cold water region of the East/Japan Sea, the North Korean Cold Current turns to the east near 39$^{\circ}$N after meeting the East Korean Warm Current, then flows eastward. The degree of penetration depends on the strength of the positive wind stress curl, according to the ventilation theory. Various current meter moorings indicate strong and oscillatory deep currents in various parts of the basin. According to some numerical experiments, these currents may be induced by pressure-topography or eddy-topography interaction. However, more investigations are needed to explain clearly the presence of these strong bottom currents. This study concludes the importance of topographical coupling, isopycnal outcropping, different wind forcing and the branching of the Tsushima Warm Current on the circulation of the East/Japan Sea.

• 한국수산과학회지
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• 제36권2호
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• pp.170-177
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• 2003

This study is to analyze the influence of the Tsushima Warm Current (TWC) on the variation of sound speed in the southern part of the East Sea. Sound speed is calculated by method of Chen and Millero (1977:, based on the CTD data measured in June of 1996. Sound speed in the central part of the TWC is about $45ms^{-1}$ more fast than that in the other regions without the TWC. Sound speed minimum layer (SML) in the TWC region exists between loom and 341 m, while it exists between 260m and 290m in the non-TWC region. SML distributes along the path of TWC over continental shelf in the coastal waters of Japan.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2000년도 춘계수산관련학회 공동학술대회발표요지집
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• pp.181-182
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• 2000

Due to the instability of the EKWC, the oceanic conditions in the East Sea are affected by the fluctuations of the moving paths of the TWC, polar fronts, and warm eddies. In particular, warm eddies play an important role in spreading the surface water of the East Sea from its southern coastal region to its interior region (Isoda, 1994). However, the fluctuation characteristics of the meandering TWC and the warm eddies in the East Sea are not yet known due to the instability of the TWC. Hideaki(1999) showed that the moving paths and features of the TWC in the coastal regions of Japan were not constant. (omitted)

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제11권12호
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• pp.419-428
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• 2022

플래시 메모리는 in-place 수정이 불가능한 특성을 가지기 때문에 out-of-place 방식으로 쓰기 작업을 수행한다. 덮어쓰기가 발생한 오래된 페이지는 유효하지 않은 페이지로 전환된다. 유효하지 않은 페이지들은 높은 오버헤드를 가진 가비지 컬렉션 과정을 유발한다. 가비지 컬렉션은 많은 읽기, 쓰기 작업을 유발하기 때문에 플래시 메모리의 주요 성능 이슈 중 하나이다. 2R에서는 OLTP(On-Line Transaction Process) 워크로드의 I/O 특성을 가비지 컬렉션 알고리즘에 적용하여 WAF(Write Amplification Factor)를 개선하였다. 본 논문에서는 접근 간격이 긴 페이지들을 추가로 분리하는 2R++를 통해 2R에서 발생하는 지역 오염 문제를 해결했다. 2R++는 블록 당 추가 bit를 도입해 second chance mechanism 기반으로 warm 페이지를 분리해서 warm 페이지가 cold 페이지로 오인 식별되는 것을 방지한다. TPC-C와 Linkbench에 대해 알고리즘 별 성능 비교 실험을 진행하였고, 그 결과 2R++의 WAF는 2R대비 각각 57.8%, 13.8%의 개선을 이루어냈음을 확인했다.

• 한국수산과학회지
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• 제35권3호
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• pp.265-272
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• 2002

동한난류 주변 해역의 해색전선과 수온전선의 공간적 분포 특성을 CZCS와 AVHRR 위성자료를 이용하여 살펴보았다. 동한난류 주류의 난수 streamer 주변 해역의 색소농도와 SST의 공간적 분포를 살펴본 결과, 식물플랑크톤의 흡수보다는 황색물질이나 용존유기물질과 같은 부유물질에 의해 높은 색소농도를 나타낸 연안냉수해역, 연안의 부유물질에 의한 영향과 식물플랑크톤에 의한 영향이 혼합된 특성이 나타난 색소농도가 높은 수온전선의 냉수해역, 외해수의 특성과 유사한 순수한 식물플랑크톤의 영향에 의해 색소농도가 높은 난수중첩해역, 식물플랑크톤의 홉수에 의해 지배를 받고 있으나 색소농도가 적은 난수해역, 식물플랑크톤의 흡수에 의한 영향으로 색소농도가 높은 외해해역의 5개 범주로 구분할 수 있었다. 동해안을 따른 연안냉수해역의 높은 색소농도의 확장은 동한난류의 흐름에 크게 영향을 받고 있으며, 동한난류의 난수 내부에 있는 낮은 색소농도와 분리된다. 또한, 동한난류해역 주변의 색소 농도와 SST 사이의 관계는 전체적으로, 색소농도가 높은 곳은 수온이 낮은 곳에 나타나고 있으며, 색소농도가 낮은 곳은 수온이 높은 곳에서 나타났다. 색소농도가 가장 높게 나타난 것은 수온전선해역 냉수쪽에서 가장 높은 550nm 반사와 비교적 높은 443nm 흡수와 일치하는 일반적인 연안수와 같이 식물플랑크톤 단독으로 나타나는 것이 아니라 부유물질과 동시에 나타났다. 그리고, 또 다른 색소농도의 높은 농도가 외해수에서 나타난 것과 유사하게 난수 streamer 내부에서 나타났으며, 이것은 연안의 부유물질의 영향은 거의 받지 않은 식물플랑크톤에 의해 색소농도가 높은 것을 알았다. 동한난류 해역과 같이 색소농도가 높은 해역에서 SST와 색소농도 영상만으로 복잡한 물리 생물학적인 현상에 기인한 모든 현상을 이해하기는 어렵지만, 광범위한 해역에서 이러한 현상을 이해하는데 위성자료는 효과적인 수단으로 판단된다. 또한, 현재 운용중인 NASA의 Seastar에 탑재된 SeaWiFS (Sea-viewing Wide Field-of·view Sensor)에 의한 보다 정확한 식물플랑크톤 색소농도 자료는 현장에서 측정된 관측자료와 더불어 동한난류 해역의 물리$\cdot$생물학적인 시공간변동을 이해하는데 많은 도움을 줄 것이라 사료된다.