• Title/Summary/Keyword: Isabu

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Naming of Undersea Features in the East Sea (동해 해저지형의 명명)

  • Kwon, Youg-Rak;Choi, Jing-Yong
    • Journal of the Korean Geographical Society
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    • v.41 no.5 s.116
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    • pp.623-629
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    • 2006
  • At present, 3 names about undersea features in the East Sea - Korean Plateau, Tsushima Basin, Syun-yo Bank - are listed on Gazetteer Any explanations are not given for registration of these names. Just it seems that the names written on International marine chart(INT 511) were recorded to Gazetteer. Furthermore Tsushima Basin and Syun-yo Bank have no oceanographic, geologic reason and geographical relevance, and the names should be replaced by Ulleung Basin and Isabu Tablemount, respectively, that is deeply related to geographical relevance and genetic origin.

Trace Element in the Indian Ocean: Current Research Trends and Future Needs (인도양에서 미량원소 연구 동향 및 향후 연구 방향)

  • Kim, Intae
    • Ocean and Polar Research
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    • v.43 no.4
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    • pp.335-352
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    • 2021
  • Trace elements in the ocean have been known as essential micronutrients for the primary production of phytoplankton and the growth of marine organisms. The GEOTRACES program beginning in the mid-2000 provided a new understanding of the distribution, origin and behavior of trace elements in the ocean, together with the establishment of both clean seawater sampling and trace element analysis techniques. The Indian Ocean, one of the major oceans, is relatively the least explored area, despite playing an important role in global climate variability. Although trace element observations have recently been conducted in the Indian Ocean by Japanese-and Indian scientists, relatively not much study has been done compared to the Atlantic, Pacific and Polar Regions. Recently, together with the launch of R/V Isabu, a 5,000-ton grade large- and comprehensive research vessel, the observations of trace elements has been conducted in the Indian Ocean for the first time in Korea since 2018. In this paper, we introduce the key results of currently conducted GEOTRACES expedition in the Indian Ocean to present future trace element research directions in the Indian Ocean, and also reviewed the preliminary results in the Indian Ocean studies from Korea. In the 2020s, new Indian Ocean GEOTRACES projects are planned around European countries, and it is time for Korea to prepare for the next phase of the trace element study in the Indian Ocean in line with these international trends.

The Study of Formation for Dokdo Seamounts at the Northeastern Part of the Ulleung Basin Using Gravity and Magnetic Data (중력 및 자력자료 분석에 의한 울릉분지 북동부 독도 및 주변 해산들의 형성 연구)

  • Kim, Chang-Hwan;Park, Chan-Hong;Ko, Young-Tak;Jung, Eui-Young;Kwak, Jun-Young;Yoo, Sang-Hoon;Min, Kyung-Duck
    • Economic and Environmental Geology
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    • v.40 no.2 s.183
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    • pp.153-170
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    • 2007
  • Loading time and loading environment of the Dokdo seamounts were studied from flexure model and VGP(Virtual Geomagnetic Pole) determined by gravity and magnetic data. In spite of their similarity in size. a large difference about 50 mGal between gravity anomaly peaks of Dokdo and the Isabu Tablemount suggests different compensation degrees. Flexural modeling results show that the flexural rigidity(effective elastic thickness) of lithosphere for Dokdo is stronger(thicker) than that for the Isabu Tablemount. Also, it implies that the age of lithosphere at the time of loading of the Isabu Tablemount may be younger than that of Dokdo. Magnetic anomalies occur complicated over the Dokdo seamounts. Paleomagnetism was studied from VGP estimated by the least square and the seminorm magnetization methods with 1500 m upward continued magnetic anomalies. Age dating of Dokdo from previous study, flexural modeling, VGP, and geomagnetic polarity time scale suggest that after the cease of spreading in the Ulleung Basin, the Isabu Tablemount was formed first in normal polarity interval and followed by Dokdo. Also, they indicate that the fist large eruption of Dokdo was in normal polarity interval and the second large eruption in reversed polarity interval. The Simheungtaek Tablemount was formed in normal polarity interval between the formations of the Isabu Tablemount and Dokdo. These loading times for the Dokdo seamounts show a good coherence with the compressive stress period after the end of the opening of the East Sea. The Dokdo seamounts probably was caused by volcanism associated with the compressive stress.

Ship-Borne Global Navigation Satellite System (GNSS) for Ionospheric Total Electron Content Monitoring: Preliminary Results from ISABU Experiments (선박 GNSS(Global Navigation Satellite System) 자료를 사용한 전리권 정보 산출 실험: 이사부호 초기 결과)

  • Dong-Hyo Sohn;Byung-Kyu Choi;Junseok Hong;Gyeong Mok Lee;Woo Kyoung Lee;Jong-Kyun Chung;Yosup Park
    • Journal of Space Technology and Applications
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    • v.4 no.3
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    • pp.199-209
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    • 2024
  • In this study, we calculated total electron content (TEC) using ship-borne global navigation satellite system (GNSS) observations and validated the results by comparing the ground-based TEC. GNSS is an effective tool for monitoring the ionosphere as it allows 24-hour observations, is low cost, and is easy to install. However, most GNSS stations are located on land, which leads to a lack of data from the ocean. Therefore, we conducted an experiment collecting GNSS data in the ocean by installing GNSS observation systems aboard the research vessel 'ISABU', operated by the Korea Institute of Ocean Science and Technology. We estimated TEC using GNSS data from July 30 to August 24, 2021. From the results, we confirmed daily and latitudinal variations of TEC as expected. Additionally, we compared the results with TEC derived from nearby ground-based GNSS stations and then verified similar variations. Based on these results, we plan to research ionospheric climatology using long-term data and assess its potential for ongoing ionospheric monitoring.

Wave Transformation using Modified FUNWAVE-TVD Numerical Model (수정 FUNWAVE-TVD 수치모형을 이용한 파랑변형)

  • Choi, Young-Kwang;Seo, Seung-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.6
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    • pp.406-418
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    • 2015
  • The present modified FUNWAVE-TVD model, which is a modification to its previous version 2.1, is applied to solitary wave propagation and is tested against the experiments of Vincent and Briggs(1989) and Luth et al.(1994). The eddy viscosity breaking scheme is used for comparison with the existing study in the case of breaking experiment. The symmetry of wave-induced current is maintained when the modified model is employed to Vincent and Briggs(1989) breaking experiment, but the symmetry of wave-induced current in previous model is not maintained. A better agreement with the breaking experimental data is obtained in the modified model using eddy viscosity breaking scheme than the shock capturing breaking scheme using nonlinear shallow water equation. For comparison with the schemes in the model, the fourth order MUSCL-TVD scheme by Erduran et al.(2005) and the third order MUSCL-TVD scheme using minmod limiter is applied, and the numerical solutions of solitary wave are compared.

Comparison of Numerical Solutions by TVD Schemes in Simulations of Irregular Waves Propagating over a Submerged Shoal Using FUNWAVE-TVD Numerical Model (FUNWAVE-TVD 수치모형을 이용한 수중천퇴를 통과하는 불규칙파의 수치모의에서 TVD 기법들에 의한 수치해 비교)

  • Choi, Young-Kwang;Seo, Seung-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.4
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    • pp.143-152
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    • 2018
  • Numerical convergence and stability of TVD schemes have been applied in the FUNWAVE-TVD model were compared. The fourth order accurate MUSCL-TVD scheme using minmod limiter suggested by Yamamoto and Daiguji (1993), the fourth order accurate MUSCL-TVD scheme using van-Leer limiter suggested by Erduran et al. (2005) and the second order accurate MUSCL-TVD scheme using van-Leer limiter in Zhou et al. (2001) were compared. Comparisons of the numerical scheme were conducted with experimental data of Vincent and Briggs irregular wave experiments. In comparison with the fourth order accurate scheme using van-Leer limiter, the fourth order accurate scheme using minmod limiter is less dissipative but required lower CFL condition for stable numerical solution. On the other hand, the scheme using van-Leer limiter required smaller resolution spatial grid due to numerical dissipation, but relatively higher CFL condition can be used compared to the scheme using minmod limiter. In the breaking wave experiments which were conducted using high resolution spatial grid to reduce numerical dissipation, the characteristic of the schemes can be clearly observed. Numerical instabilities and blow-up of the numerical solutions were found in the irregular wave breaking simulation with the scheme using minmod limiter. However, the simulation can be completed with the scheme using van-Leer limiter, but required low CFL condition. Good agreements with the observed data were also observed in the results using van-Leer limiter.

A Study on the Outport for the conquest of Usanguk through the Location Analysis of Natural Environment in the Port of the East Coast (동해안 항포구의 자연환경 입지분석을 통한 우산국 정벌의 출항지 검토)

  • JANG, Dong-Ho;KIM, Jang-soo
    • Journal of The Geomorphological Association of Korea
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    • v.17 no.3
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    • pp.59-75
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    • 2010
  • In this study, location evaluation of the natural environment of ports in the Joseon Dynasty was carried out to investigate the outport of east coast for the conquest of Usanguk. As a result of study, there were 55 ports and naval stations in the Joseon Dynasty, including the Yeongokpo, Aninpo, Samcheokpo, Susanpo, and Wolsongpo. As a result of the restoration work in the sea level that was done in the sixth century, the sea level at that time was about 1m higher than that at present. In terms of the location type, three types were identified via natural-environment analysis. Location type I consists of a total of 21 ports suitable for defense due to the sand spit in all the sides and because it is located in the bay of small and medium rivers. Location type II is composed of 22 ports close to the open seas, and location type III consists of a total of 12 ports centering on the bay. A total of nine ports satisfied the location factor in the shortest distance analysis(targeting location type I), 15 ports in the slope analysis, 13 ports in the hinterland analysis, 13 ports in the visibility analysis, and 11 ports in the ocean current analysis. It was found in the final evaluation that the I level regions consist of two ports(Obunjin and Mangyangjin). Obunjin has a location characteristic that is advantageous for defense and that makes it suitable to serve as an anchorage harbor for a large-scale fleet as its water level is deep and as it has a wide embayment. In conclusion, Obunjin is considered the outport that has the highest possibility of serving as Isabu's departure port for the conquest of Usanguk.

The Origin and Development of Korean Names (우리 성명(姓名)의 생성 발달에 대하여)

  • 도수희
    • Lingua Humanitatis
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    • v.1 no.1
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    • pp.255-274
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    • 2001
  • This paper examines the history of Korean names, focusing on the structural characteristics and the literal meanings of those for kings and ordinary people. Roughly speaking, the Korean surname system traces its source to China. Historical records show that the Chinese were already using their family names around 1000 B.C. After a millennium or so, the Korean began to follow suit. Initially, however, surnames were in regular use among kings and their kin only: it was not until the late Shilla dynasty, around A.D. 800, that the commoners began to have Heir surnames. And yet, surnames still tended to be limited to men of noble birth, until around A.D. 1000. Though the Korean surname system may be said to have its origin in Chinese, there are no lack of native surnames that have as long a history, e.g., Hae, Bak, Sok, Sol, Ul, and Ol. Typical surnames of Chinese origin that are found during the late Shilla dynasty, around A.D. 900, include Jang (as in Jang Bogo) and Choi (as in Choi Chiwon). Unlike those of Chinese origin, typical Korean names during the age of Three Nations tended to allude to nature or natural phenomena, as can be witnessed in Bit 'light,' Balgum 'bright,' Nuri 'world,' and Soidori where soi means 'steel' and dol 'stone,' Other surnames abound that have to do with river, stream, field, prairie, and so on. King Muryong's original name was Sama, a variant of som 'island,' indicating where he was born. A person skilled in archery was called Jumong or Hwalbo. Baembo was so called because he 'crawls like a snake, baem,' In these last two examples, bo, as well as its variant bu, functions as a suffix, and is also found in Cochilbu, Isabu, Babo, Nolbu, Hungbu, etc. The tradition of using this kind of native Korean names has gradually disappeared, giving place to the names of Chinese style-although very recently we see an on-going movement toward using native names.

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Design of Pull Box Members on the Landing Pier Using Finite Element Analysis of a Steel Plate (강재 플레이트 유한요소해석을 이용한 잔교 상부의 풀 박스 부재의 선정)

  • Kim, Sungwon;Hong, Hyemin;Han, Taek Hee;Seo, Seung Nam
    • Journal of Coastal Disaster Prevention
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    • v.4 no.3
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    • pp.111-118
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    • 2017
  • In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

Eruptive History of the Ulleungdo-Dokdo Volcanic Group, the East Sea: a Multi-Scale Approach (동해 울릉도-독도 화산그룹 분화사 다중스케일 연구)

  • Kim, Gi-Bom;Lee, Jae-Hyuk;Ahn, Ho-Jun;Je, Yoon-Hee
    • Journal of the Korean earth science society
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    • v.43 no.1
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    • pp.140-150
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    • 2022
  • This paper focuses on introducing the concept of the multi-scale study on the Ulleungdo-Dokdo Volcanic Group in the East Sea and recent new findings from it. Multi-channel seismic reflection data reveals that the major volcanic activities of the Ulleungdo-Dokdo Volcanic Group took place between 5 and 2.5 Ma, which were propagated from Isabu Tablemount on the eastern end to the Ulleung Island on the western end. The terrestrial Ulleung Island was built via 5 stages, which eventually formed a 3 km-wide caldera, named Nari Caldera, and a volcanic dome, named Albong, within the caldera. The Albong and the unit N-1, the earliest phreatomagmatic explosive phase of the Albong volcano, were generated from a new magma injected into the existing phonolitic body. The generally trachyandesitic bulk rock composition of the pumice in unit N-1 and Albong is attributed to the contamination of the new magma by mafic cumulates at the base of the existing phonolitic chamber. The lines of evidence of a new magma injection point toward that Ulleung Island is an active volcano with a live subvolcanic magma plumbing system.