• 대한원격탐사학회지
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• 제22권5호
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• pp.397-402
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• 2006

China Coastal Water (CCW) usually appears in the seas surrounding Jeju Island annually (June-October) and is very pronounced in August. The power spectrum density (PSD), sea level anomalies (SLAs), and sea surface temperatures (SSTs) were found to peak annually and semiannually. The peaks at intervals of 80-, 60-, and 43-days are considered to be influenced by CCW and the Kuroshio Current. Generally, low-salinity water appears to the west of Jeju Island from June through October and gradually propagates to the east, where CCW meets the Tsushima Current. Empirical orthogonal function (EOF) analysis of SLAs and SSTs indicated that the variance in SLAs and SSTs was 55.70 and 98.09% in the first mode, respectively. The PSD for the first mode of EOF analysis of SLAs was stronger in the western than in the eastern waters because of the influence of CCW. The PSD for the EOF analysis of SSTs was similar in all areas (the Yangtze Estuary and the waters to the west and east of Jeju Island), with a period of approximately 260 days.

• Fisheries and Aquatic Sciences
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• 제19권9호
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• pp.36.1-36.3
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• 2016

Balssaxius habereri (Balss, 1903) has been newly reported in Korean waters. This species was previously known from the Pacific coast of northern Japan, Korea Strait, Yellow Sea, and Japanese coast of the East Sea. Specimens were collected from western Jeju Island using otter trawls at depths of 65-85 m. Regarding Korean axiid shrimps, a single species, Boasaxius princeps (Boas, 1880), previously known as Axiopsis princeps in Korea, has been recorded. B. habereri is easily distinguished from B. princeps as it does not have tufts of setae on its body and males do not have the first pleopod. Morphological descriptions and color photos of the specimens are provided.

• 대한전자공학회논문지TC
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• 제48권1호
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• pp.16-24
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• 2011

해양에서의 음속은 수온, 염분, 압력에 의한 실험식으로 계산되며 해양에서의 평균 염분은 약 34 psu (practical salinity unit)로 수성이나 수평 거리에 따른 변화가 대부분 수 psu 이하이기 때문에 음속에 크게 영향을 마치지 못한다. 그러나 최근 여름철에 중국 양쯔강 범람에 의해서 24 psu 정도의 저염수가 제주 서부 해역으로 유입되는 사례가 발생하고 있으며 이 저염수는 음속에 영향을 미친다. 본 논문에서는 이러한 환경 변화가 수중통신에 미치는 영향을 분석하였다. 즉, 저염수로 인한 음속구조의 변화를 계산하였고, 저염수층 내에서 송수선 수심과 전달거리를 바꿔가며 음파 전달 경로를 모의하여 통신 채널을 추정하였으며, BPSK(Binary phase shift key) 변조방식을 이용하여 비트 오류율을 계산하였다. 동일한 실험 조건하에 저염수가 없는 경우의 성능을 비교하여, 저염수가 통신 성능에 어떠한 영향을 미치는가에 대해 분석하였다. 저염수는 수심 약 20m까지의 표층부에서 음속의 기울기를 양의 기울기로 변화시켜 음과 채널을 형성하였고, 표층부에서 대부분의 송수신 신호의 비트 오류율을 감소시키는 경향을 확인하였다. 본 논문의 저염수에 의한 수중 통신 성능에 미치는 영향을 분석한 결과는 정확한 해양 통신 및 탐지 성능분석을 하기 위해서는 해양환경의 변화를 고려하는 것이 매우 중요하다는 것을 시사한다.

• 대기
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• 제26권4호
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• pp.599-615
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• 2016

This study investigates the accuracy of short-term ocean predictions during the development of ocean stratification for the Korea Meteorological Administration (KMA) Global Seasonal Forecast System version 5 (GloSea5) as well as the effect of atmosphere-ocean coupling on the predictions through a series of sensitive numerical experiments. Model performance is evaluated using the marine meteorological buoys at seas around the Korean peninsular (KP), Tropical Atmosphere Ocean project (TAO) buoys over the tropical Pacific ocean, and ARGO floats data over the western North Pacific for boreal winter (February) and spring (May). Sensitive experiments are conducted using an ocean-atmosphere coupled model (i.e., GloSea5) and an uncoupled ocean model (Nucleus for European Modelling of the Ocean, NEMO) and their results are compared. The verification results revealed an overall good performance for the SST predictions over the tropical Pacific ocean and near the Korean marginal seas, in which the Root Mean Square Errors (RMSE) were $0.31{\sim}0.45^{\circ}C$ and $0.74{\sim}1.11^{\circ}C$ respectively, except oceanic front regions with large spatial and temporal SST variations (the maximum error reached up to $3^{\circ}C$). The sensitive numerical experiments showed that GloSea5 outperformed NEMO over the tropical Pacific in terms of bias and RMSE analysis, while NEMO outperformed GloSea5 near the KP regions. These results suggest that the atmosphere-ocean coupling substantially influences the short-term ocean forecast over the tropical Pacific, while other factors such as atmospheric forcing and the accuracy of simulated local current are more important than the coupling effect for the KP regions being far from tropics during the development of ocean stratification.

• Journal of Advanced Marine Engineering and Technology
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• 제35권4호
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• pp.491-499
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• 2011

1999년부터 운영이 시작된 팔미도, 어청도 DGPS 해상 기준국을 시작으로 우리나라에서는 총 17개의 DGNSS 기준국을 운영하고 있는 명실상부한 DGNSS 운영 인프라의 강국이 되었다. 본 논문은 DGPS 해양 기지국을 근간으로 사용하여 우리나라의 대표적인 정기여객선 항로 구간인 제주에서 인천, 부산에서 제주, 제주에서 녹동 구간의 300 kHz 주파수의 해상 및 육상에서의 전파특성을 측정하여, 해안 DPGS 기준국에서 서비스 범위를 조사함으로써, 우리나라 DGNSS 서비스 영역을 측정하였다. 서 남해안의 선박 항로구간의 DGPS 서비스 도달범위를 확인해 본 결과 우수한 품질의 전파신호가 100 NM(권장서비스 범위) 이상 도달됨을 확인하였다. 또한 이를 통하여 선박 안전항행 및 다양한 해양안전시설물에 대하여 위치보정정보의 활용과 향후 DGPS 해양 기준국 확장에 유용할 것으로 판단된다.

• Ocean and Polar Research
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• 제43권4호
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• pp.307-320
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• 2021

Udo Rhodolith Beach is a small-scale, mixed sand-and-gravel beach embayed on the N-S trending rocky coast of Udo, Jeju Island, South Korea. This study analyzes the short-term topographic changes of the beach during the extreme storm conditions of four typhoons from 2016 to 2020: Chaba (2016), Soulik (2018), Lingling (2019), and Maysak (2020). The analysis uses the topographic data of terrestrial LiDAR scanning and drone photogrammetry, aided by weather and oceanographic datasets of wind, wave, current and tide. The analysis suggests two contrasting features of alongshore topographic change depending on the typhoon pathway, although the intensity and duration of the storm conditions differed in each case. During the Soulik and Lingling events, which moved northward following the western sea of the Jeju Island, the northern part of the beach accreted while the southern part eroded. In contrast, the Chaba and Maysak events passed over the eastern sea of Jeju Island. The central part of the beach was then significantly eroded while sediments accumulated mainly at the northern and southern ends of the beach. Based on the wave and current measurements in the nearshore zone and computer simulations of the wave field, it was inferred that the observed topographic change of the beach after the storm events is related to the directions of the wind-driven current and wave propagation in the nearshore zone. The dominant direction of water movement was southeastward and northeastward when the typhoon pathway lay to the east or west of Jeju Island, respectively. As these enhanced waves and currents approached obliquely to the N-S trending coastline, the beach sediments were reworked and transported southward or northward mainly by longshore currents, which likely acts as a major control mechanism regarding alongshore topographic change with respect to Udo Rhodolith Beach. In contrast to the topographic change, the subaerial volume of the beach overall increased after all storms except for Maysak. The volume increase was attributed to the enhanced transport of onshore sediment under the combined effect of storm-induced long periodic waves and a strong residual component of the near-bottom current. In the Maysak event, the raised sea level during the spring tide probably enhanced the backshore erosion by storm waves, eventually causing sediment loss to the inland area.

• 한국환경과학회지
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• 제23권4호
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• pp.649-660
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• 2014

Spatial and temporal patterns of precipitation and temperature occur with regard to aspect and elevation of Mt. Halla in Jeju Island. Therefore, there is a need to predict regional drought associate with them to mitigate of impacts of drought. In this study, regional drought is predicted based on Palmer drought severity index (PDSI) and standardized precipitation index (SPI) using future (2015~2044) climate change scenario RCP (representative concentration pathways) 4.5 classified as 24 regions according to aspect and elevation. The results show that number and duration of drought will be decrease in Jeju Island. However, severity of severe drought will be increase in western and northern aspect with under 200 meters above mean sea level. These findings provide primary information for developing the proactive strategies to mitigate impacts of drought by future climate change in Jeju Island.

• 자원환경지질
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• 제14권2호
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• pp.77-91
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• 1981

An airborne magnetometer survey was carried out over an offshore area of about $200,000km^2$ from the southeastern, southern and western part of Korea. Detailed magnetic studies on the geological structure of the southern part of above area ($100,000km^2$) was accomplished. Residual aeromagnetic map was made in order to delineate magnetic provinces, magnetic lineaments and sedimentary basins by application of least square method using computer system. To determine the depth of the sedimentary basins pseudo-gravimetric method was applied. 1. The area studied is divided into four magnetic provinces for the purpose of interpretation on the basis of the magnetic maps. 2. Near shore area and its attached islands of southern part (fiirst and second magnetic province) can be regarded as being the extension from the land geology due to presentation of strong magnetic anomalies and shallow magnetic basements. 3. Magnetic lineament 1-1 is strong magnetic anomalous region which is presumably relevant to volcanic activities in Cretaceous. The depth of magnetic basement of the lineament was determined to 1,500 m. Negative magnetic anomalous zones B1-1 and B1-2 which represent Tertiary basins showed depth of magnetic basement 3 km and 4 km each. The latter can be interpreted as extension of the Taiwan basin which is consisted of Tertiary sediments. 4. Magnetic lineament 2-1 coincide with Rainan-Fukien massif running NE-SW direction. A lineament located in central part of magnetic lineament 2-1 is well connected with extension of Sobacksan anticlinal axis on land. Volcanic rocks in Gyongsang system concentrated along this lineament. 5. The characteristics of magnetic pattern in the southern Yellow sea basin of western part of Jeju island show weaker magnetic anomalies and deeper magnetic basements than first and second magnetic provinces indicating geological structure of this basin seems to be quite different from that of Jeju strait. 6. In southern part of Jeju island, smoother magnetic pattern develope southward. Maximum depth of magnetic basement in sedimentary basins BIV-1 and BIV-2 were determined down to 6,000 m increasing its thickness toward Taiwan up to 11,000 m in the shelf area off Taichung, Taiwan. Judging from the fact that hydrocarbon was founded in the Tertiary sediments of western coastal area of Taiwan, it can be expected that hydrocarbon will be existed in these sedimentary basins of southern part of Jeju island.

• 수산해양기술연구
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• 제54권2호
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• pp.146-156
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• 2018

Acoustic surveys were conducted in the seas surround the South Korea (South Sea A, South Sea B (waters around the Jeju Island), West Sea and East Sea) in spring and autumn in 2016. First, the vertical and horizontal distributions of fisheries resources animals were examined. In most cases vertical acoustic biomass was high in surface water and mid-water layers other than South Sea A in autumn and West Sea. The highest vertical acoustic biomass showed at the depth of 70-80 m in the South Sea A in spring ($274.4m^2/nmi^2$) and the lowest one was 10-20 m in the West Sea in autumn ($0.4m^2/nmi^2$). With regard to the horizontal distributions of fisheries resources animals, in the South Sea A, the acoustic biomass was high in eastern and central part of the South Sea and the northeast of Jeju Island ($505.4-4099.1m^2/nmi^2$) in spring while it was high in eastern South Sea and the coastal water of Yeosu in autumn ($1046.9-2958.3m^2/nmi^2$). In the South Sea B, the acoustic biomass was occurred high in the southern and western seas of Jeju Island in spring ($201.0-1444.9m^2/nmi^2$) and in the southern of Jeju Island in autumn ($203.7-1440.9m^2/nmi^2$). On the other hand, the West Sea showed very low acoustic biomass in spring (average NASC of $1.1m^2/nmi^2$), yet high acoustic biomass in the vicinity of 37 N in autumn ($562.6-3764.2m^2/nmi^2$). The East Sea had high acoustic biomass in the coastal seas of Busan, Ulsan and Pohang in spring ($258.7{\sim}976.4m^2/nmi^2$) and of Goseong, Gangneung, Donghae, Pohang and Busan in autumn ($267.3-1196.3m^2/nmi^2$). During survey periods, fish schools were observed only in the South Sea A and the East Sea in spring and the West Sea in autumn. Fish schools in the South Sea A in spring were small size ($333.2{\pm}763.2m^2$) but had a strong $S_V$ ($-49.5{\pm}5.3dB$). In the East Sea, fish schools in spring had low $S_V$ ($-60.5{\pm}14.5dB$) yet had large sizes ($537.9{\pm}1111.5m^2$) and were distributed in the deep water depth ($83.5{\pm}33.5m$). Fish schools in the West Sea in autumn had strong $S_V$ ($-49.6{\pm}7.4dB$) and large sizes ($507.1{\pm}941.8m^2$). It was the first time for three seas surrounded South Korea to be conducted by acoustic surveys to understand the distribution and aggregation characteristics of fisheries resources animals. The results of this study would be beneficially used for planning a future survey combined acoustic method and mid-water trawling, particularly deciding a survey location, a time period, and a targeting water depth.

• 한국어류학회지
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• 제21권3호
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• pp.167-176
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• 2009

제주도 서부 연안에서 출현하는 어종들의 군집구조와 계절변동을 알아보기 위해 2008년에 홑자망, 삼중자망 그리고 통발을 이용하여 어획물의 종조성 및 계절변동을 분석하였다. 조사기간 동안 총 13목 45과 81종이 출현하였으며 농어목과 쏨뱅이목 어종이 전체 출현종수의 69.1%를 차지하고 있었다. 시기별 출현종수는 고수온기인 7월에 54종으로 가장 많이 출현하였고 저수온기인 4월 42종으로 가장 적게 출현하였다. 시기별 출현개체수와 생체량은 9월에 895 개체, 135 kg으로 가장 높았으며 12월에 450 개체, 52 kg로 낮았다. 조사어구 중 어획량이 가장 빈약했던 홑자망을 제외한 삼중자망과 통발의 다양도 지수를 구한 결과 각각 2.88~3.22, 1.31~1.87의 범위로 변화하였고 두 어구 모두 9월에 가장 높은 값을 나타냈다. 주요 우점종은 쏨뱅이, 쥐치, 호박돔, 황놀래기 등으로서 이 어종들은 계절에 상관없이 조사해역 내에서 우점 출현하고 있었다.