• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.4
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• pp.121-132
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• 2023

Marine heatwaves (MHWs), referring to anomalously high sea surface temperatures, have drawn significant attention from marine scientists due to their broad impacts on the surface marine ecosystem, fisheries, weather patterns, and various human activities. In this study, we examined the impact of the distribution of Changjiang diluted water (CDW), a significant factor causing oceanic property changes in the East China Sea (ECS) during the summer, on MHWs. The surface salinity distribution in the ECS indicates that from June to August, the eastern extension of the CDW influences areas as far as Jeju Island and the Korea Strait. In September, however, the CDW tends to reside in the Changjiang estuary. Through the Empirical Orthogonal Function analysis of the cumulative intensity of MHWs during the summer, we extracted the loading vector of the first mode and its principal component time series to conduct a correlation analysis with the distribution of the CDW. The results revealed a strong negative spatial correlation between areas of the CDW and regions with high cumulative intensity of MHWs, indicating that the reinforcement of stratification due to low-salinity water can increase the intensity and duration of MHWs. This study suggests that the CDW may still influence the spatial distribution of MHWs in the region, highlighting the importance of oceanic environmental factors in the occurrence of MHWs in the waters surrounding the Korean Peninsula.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.141-148
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• 2003

We investigated the distribution of sea ice using various microwave remote sensing techniques including radar altimeter, radiometer, and scatterometer data in the part of Drake passage, Antarctica, between the area 45$^{\circ}$-75$^{\circ}$W and 55$^{\circ}$-66$^{\circ}$S. Topex/poseidon radar altimeter data were used to analyze the monthly distribution of sea ice surface area between 1992 and 1999 by using Geo_bad_1 flag or MGDR. From satellite radiometer measurements of DMSP's SSM/I, sea ice concentration was extracted during the period from 1993 to 1996. To select a value of ice concentration, normally ranging from 0 to 100%, that can be used as a critical value of judging the existence for ice, sea ice areas estimated from various ice concentrations of radiometer measurements were correlated with the area estimated from the radar altimeter measurements. As a result, 20% of ice concentration was selected, and, then this value was used to integrate radiometer data with radar altimeter and ERS-1/2 scatterometer data. To indirectly verify the result, the last 20 year's sea ice concentration was correlated with surface temperature data near Esper-anza Observation Station. The two data showed a high correlation coefficient of 0.86. The amount of sea ice and temperature variation were found to be closely related in the study area, and this indirectly verifies the result of this study. We provided a method to judge the existence of sea ice from ice concentration of satellite radiometer data and suggested a method to monitor more detailed temporal and spatial variation of sea ice distribution by integra-tion of various microwave remote sensing techniques.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.5
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• pp.505-513
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• 2010

This study investigate the characteristics of tidal constituents, and long-term mean sea level oscillations at Incheon bay. For this, the conditions of three tide stations around Incheon bay have examined, and carried out harmonic analysis on water level data for periods of about 40 years(1960~2007). Four major tidal constituents($M_2$, $S_2$, $K_1$, $O_1$) of each tide station showed tendency that change over the 18.61year lunar node cycle, and the type of tide at three stations is mainly semi-diurnal tides. And also, the past monthly tidal modulations are especially sensitive to the cumulative year of water level data in accuracy of tidal prediction. In case that regard the detached data at three tide stations as a single time series data of 40 years, the results of analysis on a single time series, long-term mean sea level oscillations and modulations of tidal datum at tide stations appears with a range of about 10cm, respectively. In addition, the predicted tides at the Inchcon harbor by global and regional tide models of OSU(Oregon State University) based on various satellite altimetric(Topex Poseidon, Topex Tandem, ERS, GFO) data are compared with the observed tides by KHOA(the Korea Hydrographic and Oceanographic Administration). The results show that the high resolution regional model is a quite good agreement at coastal shallow water region.

• Korean Security Journal
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• no.20
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• pp.339-363
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• 2009

The 9.11 demonstrated that terrorist attack could be more serious problem than the war in our modern life. No countries in the world have evaded being a target for terrorists today. As well as South Korea, the whole world must share attentions and responsibilities for fighting against the terrorism. Since the international terrorist groups have expanded their targets from Western countries to Koreans, civilian hostages are no longer other's affair; it became a serious threat to public. Increased Korean investment, trade, missionary, and travel overseas also expanded activity regions worldwide. It also result increased terrorist threats and possible abduction. The number of kidnapping crisis has increased since the terrorists use it as an effective method of sending a message. Piracy refers to a broad range of violent acts at sea, and has traditionally been regarded as common enemies. Piracy constitutes a great threat to the security of navigation as well as to the safety of vessels and crews. Lessons from hostage issues such as Korean hostage crisis in Somalia and Afghanistan show that it can cause criticism on moral issues if armed rescue missions fail or hostages are killed, so the governments and related corporations try to solve it by paying ransom. Terrorists and use these advantages in order to put a huge pressure on the governments. In this study we will look at essential characteristics and types of hostage abductions and recognition of national safety, lessons and solutions to previous Korean hostage cases in overseas. At the same time, it provides a guidelines of the direction in the fighting against terrorist groups and Piracy.

• Maritime Security
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• v.4 no.1
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• pp.1-56
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• 2022

Why has India become a key actor in the maritime-configured Indo-Pacific region? There are some external factors, but for India, its geo-strategic frontier encompassing its geopolitical and maritime interests is expanding rapidly beyond its territorial space across both the Indian and Pacific oceans amidst an increasingly arduous geopolitical and security environment. India must, therefore, acquire the ability to influence events within this strategic arena using all facets of national power, including maritime-military power. Lately, therefore, New Delhi has invested much intellectual capital to review its maritime-security strategy. India's new strategy is premised on the concept of holistic security involving the 'softer' aspects of maritime-security, and a rekindling of maritime consciousness in India, a nation that has traditionally been beset by 'sea-blindness'. The strategy adopts a region-wide, inclusive, and a more proactive approach than hitherto, as is evident in its title 'Ensuring Secure Seas: Indian Maritime Security Strategy'. While it deals with the growing concern of new non-traditional threats in the Indian littoral and the need for military deterrence and preparedness, it also addresses the imperatives for India to seek a favorable and rules-based benign environment in its immediate and extended maritime periphery, including through multi-vectored strategic partnerships dictated by its enduring principle of strategic autonomy. For a more profound and comprehensive understanding of India's maritime-security strategy, this paper examines the key unstated and implicit factors that underpin the strategy. These include India's historical and cultural evolution as a nation; its strategic geography; its geopolitical and security perceptions; and the political directions to its security forces. The paper deals specifically with India's response to maritime threats ranging from natural disasters, crime and state-sponsored terrorism to those posed by Pakistan and China, as well as the Indian Navy's envisaged security role East of the Malacca Straits. It also analyzes the aspects of organizational restructuring and force planning of India's maritime-security forces.

• Ocean and Polar Research
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• v.34 no.4
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• pp.413-430
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• 2012

To understand the scales of the spatial distribution and temporal duration of the subsurface chlorophyll-a maximum (SCM) observed in the Ulleung Basin of the East Sea, we analyzed physical and chemical data collected during the East Asian Seas Time-series-I (EAST-I) program. The SCM layer occurred at several observation lines from the Korea Strait to $37.9^{\circ}N$ in the Ulleung Basin during August of 2008 and 2011. At each observation line, the SCM layer extended from the coast to about 200 km off the coast. The SCM layer was observed between 30 and 40 m depth in the Ulleung Basin as well as in the northwestern Japan Basin along $132.3^{\circ}E$ from $38^{\circ}N$ to $42.3^{\circ}N$ during July 2009, and was observed around 50 m depth in the northeastern Japan Basin ($135-140^{\circ}E$ and $40-45^{\circ}N$) during July 2010. From these observed features, we hypothesize that the SCM layer observed in the Ulleung Basin may exist in most of the East Sea and may last for at least half-year (from the early May to late October). The nutrient supply mechanism for prolonged the SCM layer in the East Sea was not known, but it may be closely related to the horizontal advection of the nutrient rich and low oxygen waters observed in the Korea Strait between a 50 m depth to near the bottom. The prolonged development of the SCM layer in the Ulleung Basin may result in high primary production and would also be responsible for the high organic carbon content observed in the surface sediment of the region.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.2
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• pp.77-100
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• 2024

Circulation, tides, currents, harmful algal blooms, water quality, and hypoxic conditions in Jinhae-Masan Bay have been extensively studied. However, these previous studies primarily focused on short-term variations, and there was limited detailed investigation into the physical mechanisms responsible for ocean circulation in the bays. Oceanic processes in the bays, such as pollutant dispersal, changes on a seasonal time scale. Therefore, this study aimed to understand how the circulation in Jinhae-Masan Bay varies seasonally and to examine the effects of tides, winds, and river discharges on regional ocean circulation. To achieve this, a three-dimensional ocean circulation model was used to simulate circulation patterns from 2016 to 2018, and sensitivity experiments were conducted. This study reveals that convective estuarine circulation develops in Jinhae and Masan Bays, characterized by the inflow of deep oceanic water from the Korea Strait through Gadeoksudo, while surface water flows outward. This deep water intrusion divides into northward and westward branches. In this study, the volume transport was calculated along the direction of bottom channels in each region. The meridional water exchange in the eastern region of Jinhae Bay is 2.3 times greater in winter and 1.4 times greater in summer compared to that of zonal exchange in the western region. In the western region of Jinhae Bay, the circulation pattern varies significantly by season due to changes in the balance of forces. During winter, surface currents flow southward and bottom currents flow northward, strengthening the north-south convective circulation due to the combined effects of northwesterly winds and the slope of the sea surface. In contrast, during summer, southwesterly winds cause surface seawater to flow eastward, and the elevated sea surface in the southeastern part enhances northward barotropic pressure gradient intensifying the eastward surface flow. The density gradient and southward baroclinic pressure gradient increase in the lower layer, causing a strong westward inflow of seawater from Gadeoksudo, enhancing the zonal convective circulation by 26% compared to winter. The convective circulation in the western Jinhae Bay is significantly influenced by both tidal current and wind during both winter and summer. In the eastern Jinhae Bay and Masan Bay, surface water flows outward to the open sea in all seasons, while bottom water flows inward, demonstrating a typical convective estuarine circulation. In winter, the contributions of wind and freshwater influx are significant, while in summer, the influence of mixing by tidal currents plays a major role in the north-south convective circulation. In the eastern Jinhae Bay, tidally driven residual circulation patterns, influenced by the local topography, are distinct. The study results are expected to enhance our understanding of pollutant dispersion, summer hypoxic events, and the abundance of red tide organisms in these bays.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.4
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• pp.151-171
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• 2017

Most of oceanic current maps in the secondary school science and earth science textbooks have been made on the base of extensive in-situ measurements conducted by Japanese oceanographers during 1930s. According to up-to-date scientific knowledge on the currents in the Yellow Sea and the East China Sea (YES), such maps have significant errors and are likely to cause misconceptions to students, thus new schematic map of ocean currents is needed. The currents in the YES change seasonally due to relatively shallow water depths, complex terrain, winds, and tides. These factors make it difficult to construct a unified ocean current map of the YES. Sixteen major items, such as the flow of the Kuroshio Current into the East China Sea and its northward path, the origin of the Tsushima Warm Current and its path into the Korea Strait, the path of Taiwan Warm Current, the Jeju Warm Current, the runoff pattern of the Yangtze River flow, the routes of the northward Yellow Sea Warm Current, the Chinese Coastal Current, and the West Korea Coastal Current off the west coast of the Korean Peninsula, were selected to produce the schematic current map. Review of previous scientific researches, in-depth discussions through academic conferences, expert discussions, and consultations for three years since 2014 enabled us to produce the final ocean current maps for the YES after many revisions. Considering the complexity of the ocean currents, we made seven ocean current maps: two representative current patterns in summer and winter, seasonal current maps for upper layer and lower layer in summer and winter, and one representative surface current map. It is expected that the representative maps of the YES, connected to the current maps of the East Sea and the Northwest Pacific Ocean, would be widely utilized for diverse purposes in the secondary-school textbooks as well as high-level educational purposes and even for scientific scholarly experts.

• Strategy21
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• s.31
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• pp.251-293
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• 2013

해적은 공해상 해상안전을 위협 한다는 점에서 '인류공동의 적'으로 규정되어 모든 국가가 이를 규제할 수 있는 보편적 관할권이 행사되는 범죄이다. 한국을 포함한 아시아 지역 국가들은 말라카해협 통항에 관해 깊은 이해관계를 갖고 있어 해적 소탕에 대한 의지가 강한 편이다. 이러한 의지는 2006년 '아시아해적퇴치정보공유센터(ReCAAP ISO)'의 창설에 밑거름이 되었으며, 아시아 지역에서 해적이 출현하면 동 센터를 통해 17개국 회원국으로 즉시 통보되고, 주변국의 해경과 해군이 유기적인 작전을 통해 해적을 효율적으로 퇴치하고 있는 모범사례다. 그러나 2009년 소말리아 내란에 따른 무정부 상태가 지속되면서 소말리아 및 아덴만에서의 해적활동이 극성을 부리기 시작했으며, 선박납치 행위가 급증하자 세계 각국에서 함정과 항공기를 파견하여 해적퇴치 활동을 전개하고 있으나 근절되지 않을 뿐만 아니라 해적의 활동해역이 확대되고 있다. 이러한 배경 하에 시작된 본 연구는 연구결과를 중심으로 다음과 같은 대응 방안을 제시한다. 첫째, 소말리아 해적의 근본원인은 국가의 붕괴에서 비롯된 치안부재와 열악한 경제사정 등 내부적인 요인이 크기 때문에 다국적 해군 활동으로 인한 근본적인 해적퇴치에는 한계가 있다. 따라서 국제적인 차원에서 '지역협력협정'체결은 물론, 소말리아 국가재건을 위한 노력이 함께 이루어지는 종합적인 대책이 필요하다. 그러나 보다 더 근본적인 해결책은 유엔차원에서 빠른 시간 내에 소말리아가 정치적 안정을 유지할 수 있도록 정치적 차원에서의 지원이 필요하며, 해적과 테러리스트가 연계됨으로써 국제문제로 확대되지 않도록 하는 노력도 병행되어야 한다. 둘째, 해적문제는 특정국가에만 해당되는 것이 아니라 초국가적인 문제임을 감안하여 유엔안전보장이사회 결의 제1851호에서 '지역 센터' 설립을 권고하고 있는 것처럼 2006년 아시아 국가들이 설치한 ReCAAP ISO와 같은 형태의 지역국가 간 협력기구 또는 유엔 차원의 해적 전담기구를 설치하여 국제사회 공조 하에 해적에 대처하는 방안을 추진하는 것이 필요하다. 셋째, 최근 발생하고 있는 해적행위는 주로 항구 등 내수, 영해 등 연안국의 관할권이 행사되는 지역에서 발생하고 있어 유엔해양법상의 규정은 이러한 '해적' 퇴치에 더 이상 효율적이지 못하다. 국제사회는 이러한 문제점을 인식하여 국제해사기구 (IMO) 등 국제기구를 통해 영해내의 해적 처벌을 위해 최선의 노력을 기울이고 있다. 향후 궁극적으로는 유엔해양법협약의 개정을 통해 법적인 문제점이 개선되어야 한다. 넷째, 전술적인 측면에서도 지상에 기지를 두고 있는 해적들의 지도부가 그 동안 쌓아 놓은 네트워크를 이용하여 다국적 해군에 대한 정보를 수집하고 대응방안을 강구함으로써 나름대로의 생존전략을 구사할 것으로 예상된다. 특히, 선박을 납치한 후 소말리아 연안으로 이동하면서 해군함정과 대치하는 과정에서 해적들이 살상을 당하는 사례가 증가함에 따라 지금까지는 피랍된 선박의 선원을 단순히 해적활동에 참여시키거나, 항해지원을 위한 목적 등으로만 활용했는데, 앞으로는 해적들의 인명피해를 최소화하기 위해서라도 선원들을 방패막이로 활용할 가능성이 더욱 높아질 것으로 예상된다. 따라서 참가하는 해군함정 또는 부대간 해적들의 활동 관련 정보를 공유하는 등 사전에 정보를 획득하기 위한 협력을 강화해야 한다. 다섯째, 한국군함이 삼호주얼리호를 납치했던 소말리아 해적을 한국까지 대리고 와서 처벌하는 것은 불합리하고, 많은 문제점을 야기할 수 있기 때문에 향후 해적처벌을 위한 국제사법기구의 설치가 요구된다. 회원국 분담금으로 운영되는 유엔에 산하기관을 설치하여 소말리아 인접국에서 해결하도록 적극적인 노력을 경주할 필요가 있다. 마지막으로, 선박회사에서도 자국 선박이 위험구역으로 지정된 해역을 항해할 경우를 대비해서 선박자동식별 시스템 구축을 확대하고, 해적이 선박에 승선했을 경우를 대비해서 안전구역(citadel)을 설치하여 선원의 안전을 확보하는 등의 대책이 필요하다. 본 연구를 통해 해양안보는 어느 특정국가에게만 주어진 것이 아니며, 해적행위도 특정 국가의 선박을 대상으로 하는 것이 아니므로 각국 정부간 공동의 협력과 국제사회의 공조가 반드시 실현될 때 해적의 위협으로부터 선박의 안전과 국제사회의 평화가 실현될 수 있다는 것을 강조하고자 한다.

• Journal of the Korean earth science society
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• v.21 no.3
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• pp.230-249
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• 2000

Southeastern Korean Peninsula has undergone the polyphase deformations according to the changes of regional tectonic settings during the Cenozoic. Through analyses of more than 600 fault-slip data gathered in the study area, five tectonic events are revealed as the followings: (I) NW-SE transtension, (II) NW-SE transpression, (III) NE-SW pure or radial extension, (IV) NNE-SSW transpression, (V) NE or ENE-WSW transpression. Event I was induced by the pull-apart type extension of the East Sea during 24-16 Ma, which resulted in the NW-SE extension of the Tertiary Basins in SE Korea. Event II was resulted from the collision of SW Japan and Izu-Bonnin Arc (or Kuroshio Paleoland) on the Philippine Sea Plate at ${\sim}$ 15 Ma, which stopped the extension of the Tertiary Basins and originated the uplift of fault blocks in and around SE Korean Peninsula. It was continued until ${\sim}$ 10 Ma. Event III is interpreted as the post-tectonic event after the block-uplifts due to the event II, which indicates a temporal lull in activity of the Philippine Sea Plate since 10 Ma. Event IV was originated from the resumption in activity of the Philippine Sea Plate which was restarted to move toward north at ${\sim}$ 6 Ma. The event made the EW compressional structures behind SW Japan as well as in the Korea Straits, and thus the block-uplifts in SE Korea was resumed again. Lastly, event V was resulted from the gradual decrease in influence of the Philippine Sea Plate and the cooperative compression due to the subduction of the Pacific Sea Plate and the collision of the Indian Plate since 5-3.5 Ma, which generated the NS compressional structures in the offshore along the eastern coast of the Korean Peninsula and thrust up the fault-blocks toward west. This event is continuing so far, and thus is making the active faultings resulting in the present earthquakes of the Korean Peninsula.