• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.288-299
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• 2024

Indonesia's Keplauan Liau region is facing limitations in the development of connected transportation infrastructure due to its archipelago nature, budget constraints, and lack of land. Transportation demand is increasing due to its strategic location in the Malacca Strait Business Triangle and many tourist visits from Singapore and Malaysia. However, due to the nature of connecting many islands, the establishment of transportation infrastructure has not been achieved. This paper aims to predict the innovations that can be brought about by the introduction of advanced air mobility (AAM) with an electric vertical take-off and landing (e-VTOL) system through analysis and application consideration of the actual situation in Indonesia's Kepulauan Liau region. In addition, it intends to contribute to national-level review and policy establishment on the establishment of innovative transportation infrastructure using AAM, reflection in infrastructure construction plans, and active global cooperation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.201-211
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• 2022

At the center of the Noryang waterway, the Gwangyang bay area (including the Yeosu Strait) is located at the west, and the Jinju bay area (including Gangjin bay and Sacheon bay) is located at the east. Freshwater from several rivers is flowing into the study area. In particula,r the event of flood, great quantities freshwater flow from Seomjingang (Seomjin river) into the Gwangyang bay area and from Gahwacheon (discharge from Namgang Dam) into the Jinju bay. The Gwangyang and Jinju bay are connected to the Noryang waterway. In addition, freshwater from Seomjingang and Gahwacheon also affect through the Noryang waterway. In this study, we elucidated the characteristics of the tidal exchange rate and residence time for dry season and flood season on 50 frequency, considering freshwater from 51 rivers, including Seomjingang and Gahwacheon, using a particle tracking method. We conducted additional experiments to determine the effect of freshwater from Seomjingang and Gahwacheon during flooding. In both the dry season and flood season, the result showed that the particles released from the Gwangyang bay moved to the Jinju bay through the Noryang waterway. However, comparatively small amount of particles moved from the Jinju bay to the Gwangyang bay. Each experimental case, the sea exchange rate was 44.40~67.21% in the Gwangyang bay and 50.37~73.10% in the Jinju bay, and the average residence time was 7.07~15.36days in the Gwangyang bay and 6.45~12.75days in the Jinju bay. Consequently the sea exchange rate increased and the residence time decreased during flooding. A calculation of cross-section water flux over 30 days for 7 internal and 5 external areas, indicated that the main essential flow direction of the water flux was the river outflow water from Seomjingang flow through the Yeosu strait to the outer sea and from Gahwacheon flow through Sacheon bay, Jinju bay and the Daebang waterway to the outer sea.

• Journal of the Korean Geographical Society
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• v.29 no.1
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• pp.3-15
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• 1994

The purpose of this study is to investigate the origin of traditional folkhouses of Japan in connection with those of Korea. Japanese folkhouses have received much influence from the Korean Peninsular, mainland China, northern Asia and Southeast Asia. The writer believes that the main stream of folkhouse culture origineted in the Korean Peninsular and flowed into the Japanese Islands. There ara many striking similarities in the folkhouses of Korea and Japan. Firstly, double-row room houses are distributed in the northeastern part of the Korean Penininsular and all parts of the Japanese Islands, and they are classified into the five-room type and four-room type. These types are very similar in both nations in the aspects of and floorplan and distributing patterns. Because floorplan may be used as an indicator of culture regions and cultural diffusion both, nations are believed to be closely related in the interchange of cultures in ancient times. Secondly, stables are allocated to the main house, and they are called "magu" in common "Magu" means horse stable, but there are no horses in it. In ancient times, however, many horses were kept in "magu" in both countries. Thirdly, there are much similarities in the function and structure of the folkhouses of both countries. The characteristics of folkhouses of Japan could be explained as the result of cultural diffusion from the Korean Peninsular.on from the Korean Peninsular.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1307-1315
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• 2021

The Changjiang Diluted Water (CDW) spreads over the East China Sea every summer and significantly affects the sea surface salinity changes in the seas around Jeju Island and the southern coast of Korea peninsula. Sometimes its effect extends to the eastern coast of Korea peninsula through the Korea Strait. Specifically, the CDW has a significant impact on marine physics and ecology and causes damage to fisheries and aquaculture. However, due to the limited field surveys, continuous observation of the CDW in the East China Sea is practically difficult. Many studies have been conducted using satellite measurements to monitor CDW distribution in near-real time. In this study, an algorithm for estimating Sea Surface Salinity (SSS) in the East China Sea was developed using the Geostationary Ocean Color Imager (GOCI). The Multilayer Perceptron Neural Network (MPNN) method was employed for developing an algorithm, and Soil Moisture Active Passive (SMAP) SSS data was selected for the output. In the previous study, an algorithm for estimating SSS using GOCI was trained by 2016 observation data. By comparison, the train data period was extended from 2015 to 2020 to improve the algorithm performance. The validation results with the National Institute of Fisheries Science (NIFS) serial oceanographic observation data from 2011 to 2019 show 0.61 of coefficient of determination (R²) and 1.08 psu of Root Mean Square Errors (RMSE). This study was carried out to develop an algorithm for monitoring the surface salinity of the East China Sea using GOCI and is expected to contribute to the development of the algorithm for estimating SSS by using GOCI-II.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.117-124
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• 1997

Vertical profiles of dissolved Cu and Ni at the upper 400 m water layer have been determined at two stations in the central East Sea in October 1995. This is the first report on the vertical distribution of trace metals in Korea. Copper concentrations are in the range of 2.1~5.8 nmol/kg and 1.6~2.4 nmol/kg for stations S and N, respectively. The vertical profile of Cu at S is found a scavenging type (i.e., drastic decrease with increasing depth). Concentrations of Ni range from 4.3 to 7.1 nmol/kg and from 3.4 to 5.4 nmol/kg for stations Sand N, respectively. At station S, Ni is best correlated with phosphate, but not at stations N. Such difference between two stations are probably due to their different vertical distribution of water masses. Station S has a strongly stratified water column with 6 distinct water masses, but station N with a well-mixed subsurface water layer extending from 50 to 300 m depth. Extremely low salinity (31.87~31.96 psu) found at the surface water of station S was interpreted as a result of the Yangtze River effluents which were probably fed into the East Sea through the Korea Strait during the late summer. Such seasonal appearance of low salinity in southern part of the East Sea was reported previously. The concentrations of Cu and Ni at two sites are comparable to those reported in the North Pacific. It was found that Ni mostly exist as dissolved phase.

• Animal Systematics, Evolution and Diversity
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• v.11 no.4
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• pp.417-434
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• 1995

Three species (0. kinbergi, 0. sarsi and 0 . sarsi vadicola) of the genus Ophiura (Echinodermacta: Ophiuroidea) were sampled from the various localities of Korean waters (Kyonggi Bay in March and September, 1989 and February, 1994; Yellow Sea in September and October, 1992; Southern Sea and Korean Strait in May, 1992; and eastern coasts adjacent to Kangnung in April, July, October, 1993 and January, 1994). Results of the examination of 250 Operational Taxonomical Units (OTUs) are presented based on the 20 morphometric variables to evaluate their taxonomic characters and positions. In cluster analysis, 250 OTUs were divided into 3 phenons (0. kinbergi, 0 . sarsi and 0 . sarsi vadicola) at the Euclidean distance levels of 6.84 and 2 phenons (a phenon composed of 0 . sarsi and 0 . sarsi vadicola and the other of 0. kinbergi) at 7.50. Stepwise discriminant analysis was used in order to produce a good discrimination model and 13 morphological characters (the total number of comb papillae, the number of primary comb papillae and shape of comb papillae (2). etc.) were extracted. The results of canonical discriminant analysis illustrated clear distinction among 3 phenons by the distance of 8.26 between 0 . sarsi and 0. sarsi vadicola, 24.24 between 0 . kinbergi and 0. sarsi vadicola and 21.63 between 0 . kinbergi and 0 . sarsi.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.303-312
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• 2011

Analysis of high-resolution seismic profiles from the southeastern continental shelf of Korea reveals that the Holocene transgressive deposits consist of five sedimentary units characterized by retrograding or backstepping depositional arrangements. Unit I, forming a linear sediment body along the shelf margin, is an ancient beach/shoreface deposit formed during the early stage of transgression. During the transgression, the paleo-channels were backfilled with fluvial or coastal-plain sediments, forming Unit II as an incised-channel fill deposit. The near-surface sediment was reworked and eroded by shoreface erosion, forming a thin lag of sands (Unit III) on the midshelf. During the middle stage of the transgression, the shoreline may have stabilized at around 70 - 80 m below the present sea level for some period of time to allow the formation of sand ridge systems (Unit IV). Unit V in the inner shelf was deposited in an estuarine environment during the middle to late stage of transgression. Such transgressive stratigraphic architecture is controlled by a function of lateral changes in the balance among rates of relative sea-level rise, sediment input and marine processes at any given time.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.4
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• pp.291-306
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• 2021

From the climate change scenario experiments of 21 models participating in Coupled Climate Model Inter-comparison Project Phase 6, future changes of sea surface temperature (SST) and Kuroshio in the Northwest Pacific were analyzed. The spatial feature of SST change was found to be related to the change of the current speed and spatial distribution of Kuroshio. To investigate the relationship between the change in latitude of the Kuroshio extension region, which flows along the boundary between the subtropical gyre and the subarctic gyre in the North Pacific, and the large-scale atmospheric circulation due to global warming, the zero-windstress curl line for each climate change experiment from 9 out of 21 models were compared. As the atmospheric radiative forcing increases due to the increase of greenhouse gases, it was confirmed that the zero-windstress curl line moves northward, which is consistent with the observation. These results indicate that as the Hadley Circulation expands to the north due to global warming, the warming of the mid-latitudes to which the Korean Peninsula belongs may be accelerated. The volume transport and temperature of the Tsushima Warm Current flowing into the East Sea through the Korea Strait also increased as the atmospheric radiative forcing increased.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.1
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• pp.33-47
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• 2022

In this study, distribution of submarine sand ridges in the coastal waters of Korea was surveyed using multibeam echo sounder data, and the topographic characteristics of each region were identified. For this purpose, the DEM (Digital Elevation Model) data was generated using depth data obtained from the Yellow Sea and the South Sea by Korea Hydrographic and Oceanographic Agency, and then applied the TPI (Topographic Position Index) technique to precisely extract the boundary of the sand ridges. As a result, a total of 200 sand ridges distributed in the coastal waters were identified, and the characteristics of each region of the sedimentary sediments were analyzed by performing statistical analysis on the scale (width, length, perimeter, area, height) and shape (width/length ratio, height/width ratio, linear·branch type, exposure·non-exposure type). The results of this study are expected to be used not only for coastal navigational safety, but also for marine naming support, marine aggregate resource identification, and fisheries resource management.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.273-279
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• 2007

In order to estimate the sedimentation rates of continental shelf and slope of Ulleung Basin in the Southwestern East Sea, $^{210}Pb,\;^{226}Ra\;and\;^{137}Cs$ were simultaneously measured by a well-type high purity germanium(HPGe) gamma detector. $^{137}Cs$ was used to determine whether the sediment were affected by bioturbation or not, and to judge the accuracy of estimated sedimentation rates. The estimated sedimentation rates decreased exponentially from slope to basin - 0.6 cm/yr in the continental shelf, $0.3{\sim}0.4$ cm/yr in the slope, and below 0.2 cm/yr in the margin of Ulleung basin. From our and other research results, we suggest followings about sediment transport of the study area. The sediment particles were transported by coastal current from south to north through the Korea Straight. And much of them were accumulated in the shelf area. And then, the rest of sediment particles were deposited in the lower slope and the southwest margin of the basin. Also the excess $^{210}Pb$ profiles indicate that the depositional processes in the study area may have been very complicate.