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A Study on the Numerical Simulation of the Seismic Sea Waves in the East Sea based on the Boussinesq Equation (Boussinesq 방정식을 이용한 동해지진해일 수치실험 연구)

  • Kim, Sung-Dae;Jung, Kyung-Tae;Park, Soo-Young
    • Ocean and Polar Research
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    • v.29 no.1
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    • pp.9-31
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    • 2007
  • Most seismic sea waves in the East Sea originate from earthquakes occurring near the Japanese west coast. While the waves propagate in the East Sea, they are deformed by refraction, diffraction and scattering. Though the Boussinesq equation is most applicable for such wave phenomena, it was not used in numerical modelling of seismic sea waves in the East Sea. To examine characteristics of seismic sea waves in the East Sea, numerical models based on the Boussinesq equation are established and used to simulate recent tsunamis. By considering Ursell parameter and Kajiura parameter, it is proved that Boussinesq equation is a proper equation for seismic sea waves in the East Sea. Two models based on the Boussinesq equation and linear wave equation are executed with the same initial conditions and grid size ($1min{\times}1min$), and the results are compared in various respects. The Boussinesq equation model produced better results than the linear model in respect to wave propagation and concentration of wave energy. It is also certified that the Boussinesq equation model can be used for operational purpose if it is optimized. Another Boussinesq equation model whose grid size is $40sec{\times}30sec$ is set up to simulate the 1983 and 1993 tsunamis. As the result of simulation, new propagation charts of 2 seismic sea waves focused on the Korean east coast are proposed. Even though the 1983 and 1993 tsunamis started at different areas, the propagation paths near the Korean east coast are similar and they can be distinguished into 4 paths. Among these, total energy and propagating time of the waves passing over North Korea Plateau(NKP) and South Korea Plateau(SKP) determine wave height at the Korean east coast. In case of the 1993 tsunami, the wave passing over NKP has more energy than the wave over SKP. In case of the 1983 tsunami, the huge energy of the wave passing over SKP brought about great maximum wave heights at Mukho and Imwon. The Boussinesq equation model established in this study is more useful for simulation of seismic sea waves near the Korean east coast than it is the Japanese coast. To improve understanding of seismic sea waves in shallow water, a coastal area model based on the Boussinesq equation is also required.

Temperature Variation in the Ulleung Warm Eddy during 2013~2015 (2013~2015년 울릉 난수성 소용돌이의 수온변동)

  • Choi, Yong-Kyu
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.22 no.2
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    • pp.205-211
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    • 2016
  • Based on the Expendable Bathythermograph (XBT) observation and serial oceanographic observation of National Institute of Fisheries Science (NIFS) during July 2013 to July 2015, we examined the temperature variation in the Ulleung Warm Eddy (UWE) in the East Sea. The UWE was always shown during the observation periods even though it was not the whole shape. The coefficient of variation (CV) was largest in the depth of 250 m at the side of the east coast of Korean Peninsula with $3{\sim}4^{\circ}C$ in temperature. CV of the horizontal distribution at 250 m depth was also largest in the region biased along the east coast of Korea. The warm eddy moved not only to the east-west direction but also to the north-south direction in the viewpoint of horizontal distributions of temperature. This region between the Korean Peninsula and Ulleung island also is the passage of the East Korean Warm Current. This means that interaction between the East Korean Warm Current and periphery of warm eddy makes large in the variation of movement along the east coast of Korean Peninsula. The largest variation of temperature at 250 m depth seemed to be significantly correlated with the East Sea Intermediate Water (ESIW) underlying Ulleung Warm Eddy. It is suggested that the interaction between the ESIW and UWE is active in the mid-depth along the periphery of UWE.

A Study on the Applicability of East Asian Welfare State Discourse to the Development of Korean Welfare State(Regime) (서구적 동아시아 복지국가 담론의 한국에 대한 적용 가능성 연구)

  • Na, Byong Kyun
    • Korean Journal of Social Welfare Studies
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    • v.41 no.3
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    • pp.5-27
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    • 2010
  • The objective of this study is to examine the dicourse of East Asian Welfare Models and its applicability to explain the development of the Korean Welfare State(regime). The Confucianist Welfare State, representing East Asian Welfare Models has limitations in explaining the current features and dynamics of east asian welfare states. Compared to the western and northern european welfare states, the Welfare State(Regime) of Korea, one of the east asian countries show the clear differences in terms of its origin, the background of formulation, the orientation of the policy and the actors. Thus, a new approach to examine the East Asian Welfare Model is needed. As a theoretical framework, the origin and the growth of the Korean Welfare State(Regime) can be understood and explained in the boundary of concept and the theoretical framework of the Authoritative Developmental State; Historically, the democratization of the 1980s and the financial crisis of the end of 1990s in Korea contributed to the growth of the welfare policies and institutions in Korea. Japan, Taiwan and other east asian counties, such as Hong Kong and Singapore have many similarities with Korea in terms of welfare policies and institutions. Comparative studies of these countries can create significant and useful results to develop a new concept and model of East Asian Welfare States. Case studies and active academic exchanges among welfare state researchers in these east asian countries are very important to develop a new concept of East Asian Welfare State Models.

The Terrain Transformation of the Fishing Industry in East Sea Rim: Impact of Entering Chinese Fishing Fleets into East Sea on the Fishery Production, Employment and Life Threat (환동해 어업의 지형 변화: 중국어선의 동해 진출이 어업생산과 고용 및 생존 위협에 미치는 영향)

  • Choi, Young-Jin
    • The Journal of Fisheries Business Administration
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    • v.52 no.1
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    • pp.1-22
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    • 2021
  • This study aims to face common threats from the depletion of fish resources, the decline of production and employment as well as the increase of life risk in East Sea Rim countries, North Korea, South Korea, Japan and Russia due to the Chinese fishing fleets entering East Sea. The recent competition in fishing among fishing vessels and fleets of national origin operating in the East Sea has induced a significant change in the ecological landscape of the fishing fleets cluster while having influenced production and employment in the fishing industries of South Korea and Japan as well as life threat on the fishermen in North Korea. It seems that the population organizational ecological theory can be applied to this change. It can be seen as the isomorphism of the selection process over the exclusive economic zone (EEZ) to avoid the environment in which these North Korean fishing vessels are pushed against the Chinese fleet in the North Korean part of the East Sea. To resolve the fishery disputes or conflict in the common waters in East Sea, first of all, Chinese fishing fleets will be required to put international pressure so as to solve the unfairness of the illegal fishing and overfishing by the International Fishery Organization or the UN violations of the sanctions against North Korea selling fishing rights to China. Although it is not easy for South Korea to cooperate with North Korea in the short term, South Korea will be able to support the fishery infrastructure in North Korea in the mid- to the long-term to prevent the loss of innocent lives for their fishermen and to raise their incomes.

Concept Structures, Functional Equivalence and the East Asian Welfare State Discussion: An Application of Set Theory in Comparative Social Policy (개념구조, 기능적 등가물 그리고 동아시아복지국가론: 비교사회정책연구에서 집합이론의 활용)

  • Lee, Sophia Seung-yoon
    • 한국사회정책
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    • v.19 no.3
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    • pp.185-214
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    • 2012
  • After the introduction of the three welfare regimes by Esping-Andersen, discussion on 'other' types of welfare regimes was facilitated and the scholarly focus on East Asian economic development gradually shifted to the East Asian welfare states discussion from the late 1990s. Literature on East Asian welfare states increased our understanding on the characteristics of not only the East Asian welfare state as a whole but also of each country in the region. However, compared the attention given to developing variables and empirical studies on the East Asian welfare state, less attention has been given to the concept of East Asian welfare states. Recognizing the limitation in developing comparable variables without a concept analysis of the East Asian welfare states, this study highlights the importance of conceptualization and concept analysis in comparative social policy studies. This paper first discusses on the concepts, conceptualization and on the use of set theory in comparative social policy research. Next, the study argues the validity of 'functional equivalence' in the East Asian welfare state studies and critically reviews the existing literature. Lastly, this paper suggests how the concept of functional equivalence can be successfully employed for the East Asian welfare states studies with a concept analysis and by applying a set theory including the fuzzy set theory.