• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.707-718
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• 2019

Ecklonia cava Kjellman, which has recently gained popularity due to the spread of farming techniques, is expected to be developed in various varieties in the future. There exist increased needs for research on the basis of natural populations and inter-regional morphological variations. We compared the morphology of the aquaculture and natural populations from 16 coastal areas in Korea. The 18 traits found suitable for distinguishing varieties were selected from 14 measurement traits and 4 ratios related to the main morphology and characteristics of primary blade, secondary blade, and stipe. In the cluster analysis, Janggil (E4) and Sorok (S7) showed significant differences from those of the same coastal region. Two groups, including Suyou (Q6, Q8, and Q10) which was the second year of farming, of the rest of the populations from East sea and southern coast were distinguished. Three populations of Jeju were divided into a regional group. In the principal component analysis (PCA), a large number of populations from East sea and Southern coast appeared in the center with aquaculture populations. PC1 and PC2 associated with traits of secondary blade index, stipe length and diameter, stipe length/primary blade length, primary blade length and width, secondary blade number, secondary blade length and width, divided E4, S7 and populations of Jeju region. As a result, the 18 characters of this study were found to be useful as criteria for discrimination of populations with significant differences in each coastal region, and these populations were expected to be candidates for new varieties.

• Journal of the Korean Geographical Society
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• v.43 no.4
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• pp.449-465
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• 2008

Coastal lagoon has experienced a natural geomorphic development process which has been aggraded after the climax of transgression in Holocene. This study estimates superiority on landscape conservation of lagoons and degree of landscape changes during the 20th century as conservation ratios of area and shore length, and analyzes the causes of the changes and classifies the lagoons based on the data by case study of the major 7 coastal lagoons(Hwajinpo, Songjiho, Gwangpoho, Yeongrangho, Maeho, Hyangho, and Gyeongpoho) in the middle East Coast of the Korean Peninsular. Based on the conservation ratios of area and shore length, the areal change is in order of Songjiho($0.56km^2$, 92%), Hwajinpo($2.06km^2$, 90%), Yeongrangho($0.96km^2$, 86%), Hyangho($0.32km^2$, 76%), Gyeongpoho($0.90km^2$, 52%), Maeho($0.14km^2$, 50%), and Gwangpoho($0.07km^2$, 32%), and the shore length change is in order of Hwajinpo(11.90km, 100%), Hyangho(3.34km, 90%), Yeongnangho(7.21km, 89%), Gyeongpoho(7.11km, 79%), Songjiho(5.56km, 79%), Gwangpoho(1.16km, 62%), and Maeho(2.16km, 58%). Therefore, the characteristics of landscape changes of the lagoons in the study area can be represented in order of Hwajinpo(Al), Hyangho(A2), Yeongrangho(A3), Songjiho(A4), Gyeongpoho(B4), Gwangpoho(B5), Maeho(B6). Serious process for land use and industrial development has changed landscape around lagoons decreasing the area of coastal plains dramatically up to this century. Because small lagoons such as Maeho and Gwangpoho have experienced severe transformation and destruction, and Gyeongpoho was transformed into artificial lake for urbanization and tourism, they show dramatic landscape change.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.13-19
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• 2024

An analysis of the coastal water temperature in the Tongyeong waters, the eastern sea of the South Sea of Korea, revealed that the water temperature rose sharply before the typhoon made landfall. The water temperature rise occurred throughout the entire water column. An analysis of the sea surface temperature data observed by NOAA(National Oceanic and Atmospheric Administration) satellites, indicated that sea water with a temperature of 30℃ existed in the eastern waters of the eastern South Sea of Korea before the typhoon landed. The southeastern sea of Korea is an area where ocean currents prevail from west to east owing to the Tsushima Warm Current. However, an analysis of the satellite data showed that seawater at 30℃ moved from east to west, indicating that it was affected by the Ekman transport caused by the typhoon before landing. In addition, because the eastern waters of the South Sea are not as deep as those of the East Sea, the water temperature of the entire water layer may remain constant owing to vertical mixing caused by the wind. Because the rise in water temperature in each water layer occurred on the same day, the rise in the bottom water temperature can be considered as owing to vertical mixing. Indeed, the southeastern sea of Korea is a sea area where the water temperature can rise rapidly depending on the direction of approach of the typhoon and the location of high temperature formation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.4
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• pp.206-216
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• 2017

The temporal distribution of the turbulence kinetic energy (TKE) and the vertical component of Reynolds stresses ($-{\bar{u^{\prime}w^{\prime}}}$) was measured during one wave period under high wave energy conditions. The wave data were obtained at Hujeong Beach in the east coast of Korea at January 14~18 of 2017 when an extratropical cyclone was developed in the East Sea. Among the whole thousands of waves measured during the period, hundreds of regular waves that had with similar pattern were selected for the analysis in order to give three representing mean wave patterns using the ensemble average technique. The turbulence properties were then estimated based on the selected wave data. It is interesting to find out that $-{\bar{u^{\prime}w^{\prime}}}$ has one clear peak near the time of flow reversal while TKE has two peaks at the corresponding times of maximum cross-shore velocity magnitudes. The distinguished pattern of Reynolds stress indicates that vertical fluxes of such properties as suspended sediments may be enhanced at the time when the horizontal flow direction is reversed to disturb the flows, supporting the turbulence convection process proposed by Nielsen (1992). The characteristic patterns of turbulence properties are examined using the CADMAS-SURF Reynolds-Averaged Navier-Stokes (RANS) model. Although the model can reasonably simulate the distribution of TKE pattern, it fails to produce the $-{\bar{u^{\prime}w^{\prime}}}$ peak at the time of flow reversal, which indicates that the application of RANS model is limited in the prediction of some turbulence properties such as Reynolds stresses.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.28-41
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• 2024

The carbon balance serves as a valuable indicator of a plant's physiological status under diverse environmental conditions. We investigated the photosynthetic and respiratory responses of the Asian surfgrass Phyllospadix iwatensis along the northeast coast of the Korean peninsula in response to changing water temperature (ranging from 5℃ to 30℃) to estimate the seasonal whole-plant carbon balance through a series of incubation experiments. The maximum gross photosynthetic rate (P_max) showed a significant difference among the temperature treatments, while there was no significant difference in photosynthetic efficiency (α). The maximum gross photosynthetic rate of P. iwatensis reached its peaks at 20℃ treatment (101.65 μmol O₂ g^-1 DW h^-1) but decreased rapidly at 30℃. The saturation irradiance (I_k), compensation irradiance (I_c), and respiration rate (R) of P. iwatensis exhibited significant differences among the temperature treatments. The saturation irradiance increased up to 20-25℃ (121.59-124.50 μmol photons m^-2 s^-1) and sharply decreased at 30℃. The compensation irradiance and respiration rate increased steadily with rising water temperature. The ratio of P_max to R (P_max:R ratio) was the highest at 5℃ but dramatically decreased at 30℃. The whole-plant carbon balance, calculated based on photosynthetic parameters, respiration rates, and biomass, exhibited distinct seasonal variation, increasing during winter and spring and decreasing during summer and fall, which is consistent with the highest in situ growth in spring and severely limited growth at the highest water temperature conditions. Phyllospadix iwatensis displayed a negative carbon balance during late summer, fall, and winter, but demonstrated a positive carbon balance during spring and early summer. Our findings suggest that the rising seawater temperatures associated with climate change may lead to significant alterations in the seagrass ecosystem functioning along the rocky shores of the Korean east coast.

• Korean Journal of Environmental Biology
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• v.42 no.1
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• pp.80-94
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• 2024

This study aimed to examine the morphological characteristics and variation in main traits by comparing the growth of individuals of Ecklonia cava Kjellman(Laminariales, Phaeophyceae) under an aquaculture environment. This survey was conducted from April 2018 to November 2019 at the aquafarm in Jindo-gun, Jeollanam-do(South coast of Korea). To classify the morphology of individuals in the aquaculture farm of E. cava, we investigated fourteen morphological characteristics and calculated four ratios between the measured values. Juvenile individuals showed a simple or oblong lanceolate, and at 3-4 months, a short stipe and holdfast developed, along with a bladelet that developed into the secondary blade form. At 5-7 months, secondary blades were found to develop irregularly on the primary blade. At 8-10 months, the primary blade expanded and secondary blades elongated. At 11-12 months, the secondary blades became oblong. At 13-14 months, the thallus area expanded. At 15-16 months, tertiary blades were formed, the thallus became more complex, the stipe thickened, and the holdfast widened. At 17-18 months, secondary blades clearly developed along with lobes. At 19-20 months, tertiary blades developed and became similar to mature natural blades. In the principal component analysis (PCA), the monthly population of the first year(Q1) and that of the second year(Q2) of the cultured population were divided along PC1, which is related to secondary blade morphological characteristics and the holdfast width. Q2 and natural populations are distributed in descending order of volume in Jeju(J), East Coast(E), and South Coast(S) along PC2, which is related to primary blade and stipe morphological characteristics. The results of this study were judged to offer important criteria for the development of different varieties of E. cava.

• Ocean and Polar Research
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• v.44 no.4
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• pp.355-364
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• 2022

When the 60-ton-class patrol boat '72' of the Korea Coast Guard (KCG) was on duty and she accidentally collided with another patrol boat ('207', 200-ton-class) and sank. A month-long search found a small amount of lost items, but neither the crew nor the ship was found. For the first time in 39 years since the accident, the Korea Institute of Ocean Science and Technology (KIOST) searched the boat 72 using the latest integrated geophysical techniques. A number of sonar images presumed to be of a sunken ship was acquired using a combined system of side scan sonar and marine magnetometer, operated at an altitude of approximately 30 m from the seabed. At the same time, a strong magnetic anomaly (100 nT) was detected in one place, indicating the presence of an iron ship. A video survey using a remotely operated underwater vehicle (ROV) confirmed the presence of a shielding part of a personal firearm at the stern of the sunken vessel. Based on these comprehensive data, the sunken vessel discovered in this exploration was assumed to be '72'. This result is meaningful in terms of future ocean exploration and underwater archaeology, as the integrated system of various geophysical methods is an efficient means of identifying objects present in the water.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.63-74
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• 2006

In order to identify the Pb pollution and its sources in continental shelf and slope areas, Pb concentration and Pb isotope ratios ($^{207}Pb/^{206}Pb\;and\;^{208}Pb/^{206}Pb$) were determined far 6 box corer sediments collected from the southern East/japan Sea. Pb concentration, and $^{207}Pb/^{206}Pb\;and\;^{208}Pb/^{206}Pb$ ratios were constant at around $25\pm5 ppm$ and 0.842 and 2.092 from 1700 to 1930 year, respectively and increased steadily up to $40\pm5 ppm$ and 0.867 and 2.123 at the beginning of 1990s', respectively. The increase of concentration and isotope ratios in the labile fraction (leached by 2M HC1+0.5M $HNO_3$) explains their increase in bulk sediments, while Pb concentration and isotope ratios in the residual fraction were nearly constant during 300yrs. Temporal variation of Pb isotope ratios was explained by simple two end-members mixing of geo-genic and anthropogenic sources because isotope ratios and the inverse of Pb concentration showed the good linear relationships. Using Pb isotope ratios, we can constrain two Pb sources in the study area. The one is atmospheric particulates, compared with mean values of isotope ratios in atmospheric particulates collected at Jeju and Oki ;stands, based on the history of Pb emmission in Korea and China, and judged by oceanographic processes capable of homogenizing many sources. The other is local sources related to iron mills, refineries of Pb ore and of petroleum located at the coast of the study area. Isotope ratios of anthropogenic Pb can be estimated using two end-members mixing equation and were $0.879\pm0.005\;and\;2.144\pm0.008$ before 1950s' while they increased up to $0.900\pm0.008\;and\;2.162\pm0.011$ after 1980s', respectively.

• Strategy21
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• s.31
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• pp.142-163
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• 2013

Ieodo is a submerged rock within a Korea's Exclusive Economic Zone(EEZ) in the East China Sea with its most shallow part about 4.6m below the sea level which has no specific rights for the EEZ delimitation. The United Nations Convention on the Law of the Sea (UNCLOS) stipulates that any coastal state has the rights to claim an EEZ that stretches up to 200 nautical miles from its shore, except where there is an overlap with a neighboring country's claims. Korea claims that Ieodo is within its EEZ as it sits on the Korean side of the equidistant line and the reef is located on the Korea section of the continental shelf. China does not recognize Korea's application of the equidistance principle and insists that Ieodo lies on its continental shelf. According to UNCLOS, Ieodo is located in international waters, rather than one country's EEZ as the two countries have failed to reach a final agreement over the delimitation of the maritime border. This study seeks to understand the evolution of the People's Liberation Army Navy(PLAN) strategy as main obstacles for the EEZ delimitation between Korea and China. PLAN's Strategy evolves from "coastal defense" to "offshore defence", since the late 1980s from a "coastal defence" strategy to an "offshore defence" strategy which would extend the perimeter of defence to between 200 nm and 400 nm from the coast. China's economic power has increased It's dependence on open trade routes for energy supplies and for its own imports and exports. China want secure Sea Lane. PLAN's "offshore defence" strategy combines the concept of active defence with the deployment of its military forces beyond its borders. China's navy try to forward base its units and to achieve an ocean going capability. China's navy expects to have a 'Blue Water' capability by 2050. China insists that coastal states do have a right under UNCLOS to regulate the activities of foreign military forces in their EEZs. China protests several times against US military forces operating within It's EEZ. The U.S. position is that EEZs should be consistent with customary international law of the sea, as reflected in UNCLOS. U.S. has a national interest in the preservation of freedom of navigation as recognized in customary international law of the sea and reflected in UNCLOS. U.S. insists that coastal states under UNCLOS do not have the right to regulate foreign military activities in their EEZs. To be consistent with its demand that the U.S. cease performing military operations in china's EEZ, China would not be able to undertake any military operations in the waters of South Korea's EEZ. As such, to preserve its own security interests, China prefers a status quo policy and used strategic ambiguity on the Ieodo issue. PLAN's strategy of coastal defence has been transformed into offensive defence, Korea's EEZ can be a serious limitation to PLAN's operational plan of activities. Considering China'a view of EEZs, China do not want make EEZ delimitation agreement between Korea and China. China argues that the overlapping areas between EEZs should be handled through negotiations and neither side can take unilateral actions before an agreement is reached. China would prefer Ieodo sea zone as a international waters, rather than one country's EEZ.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.21-36
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• 2019

To ensure that Korea continues to grow, past governments have been consistent in following a policy of advancing into Russia, Mongolia, and Eurasia. The northern economy can expect to achieve synergistic growth because its economic structure complements that of Korea, which has high energy demand and industrial development. There is also an opportunity to accelerate the growth of the China-Russia-Mongolia economic corridor, which is based on Russia's Look East Policy, China's One Belt One Road, and the Mongolian Steppe Road initiative. The Korean government is pursuing a New Northern Policy to achieve the goal of economic cooperation and peace building with other nations, including North Korea; this policy succeeds the Northern Policy pursued by the previous government. As international economic cooperation requires transportation infrastructure, the demand for shipping, which offers more advantages than road and rail transportation, will increase; thus, it is necessary to prepare for it. Korea's port cities, which have a port that serves as the nodal point for maritime transportation, need to prepare for the New Northern Policy. In this paper, the long-term development of Seosan-Daesan port in the was planned and the North Korea's opening-op plan was considered in accordance with the New Northern Policy. Because international cooperation between the government and the provincial cities is required, cooperation with the Port Authority is needed, along with the proactive attitude of Seosan City, Chungcheongnam-do. The Seosan-Daesan port, which is the center of the liquid energy cargo center, can become the base of the New Northern Policy Region; further, the port can be an opportunity to establish its position as a peaceful economic hub on the west coast of Korea.