• Ocean and Polar Research
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• v.38 no.4
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• pp.295-301
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• 2016

The nomenclature of the sea nettle jellyfish from Korea was initially described as Dactylometra quinquecirrha Agassiz, 1862. However its identity has been questioned on the basis of its local distribution and molecular data. Here, we examined morphology and DNA sequences of nuclear rDNA using specimens collected from southern Korean waters in August 2014. Based on morphological characteristics (bell size, umbrella pattern, number of tentacles and lappets) and distribution locality, we reassign the Korean D. quinquecirrha to Chrysaora pacifica (Goette, 1886), and provide a re-description accordingly. The molecular identity of C. pacifica was further confirmed by comparison of nuclear ribosomal DNA sequences.

• Ocean and Polar Research
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• v.38 no.4
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• pp.287-294
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• 2016

Marine sponges have been a remarkably rich source of pharmacologically active and structurally diverse natural products. As a part of our continuing search for novel secondary metabolites of biomedical importance from marine invertebrate, we encountered the sponge Lipastrotethya sp. from Chuuk, Micronesia. The crude organic extract of this animal exhibited considerable cytotoxicity against the K562 cell line. Guided by the $^1H$ NMR analysis, flash chromatography of the crude extract followed by HPLC yielded a new triterpene glycoside, along with ten known saponins of the sarasinoside class. The structure of this new compound was determined by combined spectroscopic methods such as COSY, HSQC and HMBC experiment. Among these metabolites, six compounds exhibited moderate cytotoxicity against ACHN, MDA-MB-231, NCI-H23 and NUGC-3 cell lines.

• Ocean and Polar Research
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• v.38 no.4
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• pp.325-330
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• 2016

Partial high frequency bands were allocated to the operation of ocean surface radars that monitor the sea surface currents and waves in WRC-12. On that basis, government-related organizations revised the table of domestic frequency allocation. In order to study radio environments in the allocated bands for ocean radar, tests of the radio signal spectrum were carried at 7-sites using the receiver of the ocean surface radar system operated with a shutdown of the transmitter for 10-60 min. The results showed that no serious radio noises occur at 25 and 43 MHz bands, indicating a good radio environment for the ocean surface radar operation. However, at 13 MHz band, it was difficult to generate stable and confidential data from the ocean surface radar because serious radio noises occurred continuously.

• Ocean and Polar Research
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• v.39 no.2
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• pp.115-124
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• 2017

The objective of this study is to evaluate the antioxidant activity of the fruits of Ligustrum japonicum. The crude extract was successively fractionated into n-hexane, 85% aqueous methanol (85% aq.MeOH), n-butanol (n-BuOH), and water fractions by means of solvent polarity. The crude extract and its solvent fractions were evaluated for their antioxidant effect by four different assay systems: scavenging power on peroxynitrite and intralcellular ROS produced in HT-1080 cells; DNA oxidation inhibition; ferric reducing antioxidant power (FRAP). The n-BuOH fraction exhibiting potent antioxidant activity was further purified by C18 silica gel column chromatography and RP-HPLC to give tyrosol (1) and salidroside (2). The structure of isolated compounds was determined by extensive 2 D NMR experiments such as $^1H$ COSY, NOESY, HSQC and HMBC as well as by comparison with the published spectral data.

• Ocean and Polar Research
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• v.40 no.3
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• pp.145-160
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• 2018

The Paguroidea is an important group in terms of marine biodiversity. In Korea, paguroids have been studied by many taxonomists and recently we conducted comprehensive taxonomic studies on hermit crabs from the southern part of the Korean Peninsula. As a result, a checklist of 61 species of Paguroidea in South Korean water with their geographical distribution was prepared. Remarks on taxonomy, geographical distribution, and the Korean scientific names of each applicable species were also provided.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.921-928
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• 2009

As part of an evaluation for an in-vessel severe accident management strategy, a coolant injection into the reactor vessel under depressurization of the reactor coolant system (RCS) has been evaluated in detail using the SCDAP/RELAP5 computer code. A high-pressure sequence of a small break loss of coolant accident (SBLOCA) has been analyzed in the Optimized Power Reactor (OPR) 1000. The SCDAP/RELAP5 results have shown that safety injection timing and capacity with RCS depressurization timing and capacity are very effective on the reactor vessel failure during a severe accident. Only one train operation of the high pressure safety injection (HPSI) for 30,000 seconds with RCS depressurization prevents failure of the reactor vessel. In this case, the operation of only the low pressure safety injection (LPSI) without a HPSI does not prevent failure of the reactor vessel.

• Ocean and Polar Research
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• v.27 no.4
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• pp.491-495
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• 2005

The morphology of a leptocephalus Nettenchelys gephyra (Hettastornatidae) is described from one specimen collected of Pohang $(35^{\circ}46'N,\;129^{\circ}52'E)$ in the East Sea, Korea on December 2003. The body is laterally compressed. The body deepens gradually behind the head to the deepest point of the midbody range that is 15.8% of the standard length 31.7mm, then tapers gradually toward the tail. The anus is located somewhat posteriorly to midbody. There are two intestinal swellings, which are located at the 19th and 41st myomere, respectively. The vertical blood vessel's last location is at the 48th myomere. The lateral pigment spot begins at the 84th myomere.

• Ocean and Polar Research
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• v.27 no.4
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• pp.419-431
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• 2005

With the draining of land resources, and rising new economic and resources expansionism, finding a new and yet to be developed ${\ulcorner}treasure{\lrcorner}$ is often a fierce and competitive challenge among many nations. This is especially true for Korea confronted with its urgent needs to find new resources and strategy to maintain the current pace of societal demand and economic development in this often impatient and rapidly progressing world. The ocean world in the South Pacific provides potentials to quench both orders with promises of new ${\ulcorner}treasure{\lrcorner}$ of living and ecosystem resources such as new fisheries and new bioactive products as well as providing alternative aesthetic, recreational resources and critical informations on various societal problems such as extreme weather conditions and early wining of the consequences resulting from global environmental changes.

• Ocean and Polar Research
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• v.32 no.3
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• pp.255-265
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• 2010

This study evaluated economic feasibility and provided rationale for the development of the Korean Operational Oceanographic System (KOOS). KOOS is supposed to be established for the preservation and management of marine environments, and for the safety of ocean activities. Economic issues associated with operational oceanographic systems are discussed. During the operational period of KOOS associated with conservative small-input scenarios, and according to the macroeconomic inputoutput analysis, the system was estimated to generate 8.3 times its actual proposed economic investment (about KRW 327.7 billion). Other rationales that cannot be easily quantified were also discussed.

• Ocean and Polar Research
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• v.29 no.4
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• pp.311-316
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• 2007

Ocean noise may be used for monitoring wind speed and rainfall rate on the sea surface, as well as for tracking whales' migration routes. In particular, low-frequency ocean noise has recently been of concern with relation to the behavior of marine mammals. Low-frequency ocean noise has been increasing over the past few decades due to increase of ship traffic and offshore oil industry activities. Mechanical noise such as flow noise and cable strumming noise may be induced if low-frequency ocean noise is measured by cabled traditional hydrophone in high current areas. To successfully measure low-frequency ocean noise in a shallow water environment with strong current, we developed a self-recording hydrophone. This paper describes the main configurations of the self-recording hydrophone and presents some results on measured data.