• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.11a
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• pp.97-142
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• 1997

The Seoguipo Formation occurs only in a small exposure along the coast of the Seoguipo City, but in the subsurface, underlies tile western part of the Bugcheon-Pyoseon Line in the northeastern part of tile island. The Bugcheon-Pyoseon Line is presumed to be a facies boundary that reflects tile distribution of hyaloclastites resulted from submarine volcanic activity. The Seoguipo Formation is distributed in the subsurface along the part which is lower than 400m in average altitude, and occurs at El. -5.76∼-46.63m in tile southern area, El. -41.89∼-57.97m in the western area, El. -13.15∼-50.59m in the northern area. Therefore, the southern area was uplifted after the deposition of the Seoguipo Formation. In the subsurface, the vertical depth of the volcanic rocks of the Cheju Volcanic Edifice is El. -40.6m in the southern area, El. -111.3m in the western area, El. -81.5m in the northern area and El. -134.7m in the eastern area. The unconsolidated U Formation, which is, overlying the basement and about 70∼250m thickness underlies the whole island. There is a positive correlation between tile groundwater level and the depth of the subsurface distribution of the Seoguipo Formation. Consequently, it is conformed that the subsurface distribution of the Seoguipo Formation plays important role for controlling the characteristics of the reservoir of tile groundwater in Cheju Island.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.107-112
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• 2007

This study was carried out to investigate the herpeto-fauna at Hallasan National Park. We conducted a survey at 1100 Resting places, Eoseungsaengak, Donnaeko, Eorimok, Yeongsil, Gwaneumsa and Seongpanak from April, 2006 to January, 2007. A series of four families and 5 species of amphibians and 4 families and 8 species of reptiles were observed. Amphiesma vibakari ruthveni, Takydromus wolteri, Scincella vandenburghi, Coluber spinalis and Hynobius quelpartensis which are rarely appearing inland but they were frequently observed by this survey. Also, we observed Sibynophis chinensis that only inhabits Jeju island with in Korea. Jeju island has both southern and northern boundary lines for amphibians and reptiles. Amphibians and reptiles in Jeju island have a different from those inland and valuable information for biogeograpy due to dissimilar climate and isolation from continental for a long time. It is not certain whether some amphibians and reptiles, Bufo gargarizans, Rana rugosa, R. plancyi, Elaphe rufodorsata and Takydromus amurensis, inhabit Jeju island, as recorded in previous literatures, so the research on current status of them has to be carried out immediately.

• Ocean and Polar Research
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• v.28 no.2
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• pp.175-186
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• 2006

There are disputes for oil and gas development between China and Japan in the East China Sea. These involve the area where China is already carrying out activities of oil and gas development and where Japan is proclaiming its EEZ. China insists that the Chinese activities on oil and gas development area are being carried out within the Chinese jurisdictional waters even if the median line principle of Japanese proclamation is applied in delimitation. Indeed, the permit for Japanese development is causing disputes between China and Japan because its permit allows development in the waters adjacent to Chinese development area. h the event, the core of this dispute around the oil and gas field in the East China Sea relates to issues of maritime boundary delimitation and issues of resources acquisition with both states. Chinese policy on oil and gas development is to first consider development issues in accordance with a median line principle where waters toward to China from the median line should be developed by China and the area toward Japan from the median line within the Chinese continental shelf should be jointly developed. However, the Japanese position is that the East China Sea should be jointly developed, and Japan hopes to eventually convince China to accept its median line delimitation. With on-going development of such issues, Korea should establish a strategy of negotiation based on analyses of resource distributional conditions and other strategic factors in the Korean delimitation area. In particular, Korea should prepare and make the best use of joint development zone established in an agreement between the ROK and Japan concerning the development of the southern part of continental shelf adjacent to both states.

• Journal of Korean Society of Rural Planning
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• v.7 no.1 s.13
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• pp.61-76
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• 2001

During the performance of large scale tidal land reclamation project along the coast line, the construction of large scale structures such as sea-dikes, closing estuaries will induce big changes of near-shore hydraulic behavior. In this paper, its is aimed to verify the change of tide and currents after the construction of sea-dike of the Saemangeum project along the coast line. Numerical scale model "TRISULA" which development by Delft Hydraulics in the Netherlands was used. "TRISULA" is adopting the finite difference numerical scheme, and mostly using for hydro-dynamic solution along the sea and estuaries. Model boundary is covering $100{\times}170$ Km and constructed with $133{\times}337$ grids. Outer side boundary is divided 48 sections, and input 37 tidal components are gained from another big scale numerical "Yellow Sea" model. Model calibrations & verifications were performed th field tide & current datas which were measured along sea-dike alignment during Aug. $1997{\sim}Apr$. 1999. And then, numerical simulation with the tide condition dated 17 Apr. 1999 was performed with & without sea-dike construction condition for the comparison. Evaluated boundary is 20 km out-side from sea-dike alignment. Four cross lanes were set up, each of lane contains 3 points, for the comparison of sea-dike construction effects. Results showing the tidal amplitude is reducing approximately 20 cm after the construction of sea-dike during spring tide condition, amplitude 6.9m. Currents after construction of sea-dikes along the alignment, the northern part shows 50%(inner), 90%(outer) and the southern part shows 10%(inner) 50%(outer) of the currents before construction.

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.63-84
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• 1997

We carried out high-resolution(FWHM=3' .3) HI 21 cm observations of the supernova remnant(SNR) PKS0607+17 and HII region S261 using Arecibo 305-m telescope. The observation was to investigate whether the high-velocity(HV) gas detected in the southern area of PKS0607+17 by Koo & Heiles(1991) is physically associated with the SNR or not. The velocity of the HV gas ranges from +64 km/s to +87 km/s, which is difficult to result from the Galactic rotation. The HV gas could be the gas accelerated by supernova blast wave. However, because the observation of Koo and Heiles(1991) was carried out using Hat Creek radio telescope(FWHM $\simeq$ 36'), the association of the HV gas with the SNR could not be investigated. Using the Arecibo HI 21cm data, we have found that the HV gas appears m the southern part of the SNR and its velocity ranges from +61 km/s to +77 km/s. But the HV gas is scattered m the whole field, not only toward PKS0607+17 but also outside the SNR Accordingly the HV gas is probably not associated with the SNR, but is accidentally aligned along the same line of sight toward the SNR. Instead we have found that HI clouds at low velocities could be possibly associated with the SNR. In Arecibo HI 21cm channel maps the HI gas seems to surround the southern boundary of the SNR at $V_{LSR}$ = +19.6 ~ +40.2 km/s. But because the region of the Arecibo HI 21cm observation is not wide enough to examine the HI gas distribution, we investigated this area using the Berkely low-latitude HI survey data(Weaver & Williams 1974) too. There we found HI gas surrounding the radio continuum boundary of PKS0607+17 at $V_{LSR}$ = +21.6 ~ +258 km/s. It is possible that this HI gas is associated with the SNR, in which case, the velocity of the SNR $V_o$ $\simeq$ +26 km/s, its distance d $\simeq$ 12.5 kpc and its radius R $\simeq$ 145 pc. If we assume that the expansion velocity is ~10 km/s, then the age of the SNR is $\sim4.4\times10^6$ years. PKS0607+17 could be one of the oldest SNRs in the Galaxy. We also studied HI propertities of the HII region S261, which is $\sim1^{\circ}$ away from PKS0607+17. There has been no high-resolution m 21 cm observational study on S261. We discovered HI cloud located at the north-eastern part of S261 at $V_{LSR}$ = +5 km/s ~ +10 km/s, which is possibly associated with the HII region. The central velocity of the HI cloud $V_{LSR}$ = +7.2 km/s and the corresponding distance d = 1.5 kpc. This velocity is comparable to the radio recombination line velocities.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.33-41
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• 1999

A new sedimentary basin is reported from the marine multi-channel seismic data which were acquired for the hydrocarbon exploration on the southwestern Korean continental shelf in 1970. Along the southeastern part of Line 1192, the about 60-km-long basin with the thickness of 0.55~1.1 s is observed on the near-trace gather. However, both new and previous 24-fold stack sections fail to show the basin image probably due to its rugged top beneath the shallow water. The boundary contact between the basement with the velocity of about 5200m/s and the basin filling with the velocities of 4300~4700 m/s is unclear. These velocites are calculated from the corresponding shot gathers. Compared with the Haenam Basin, a neighbouring onshore Cretaceous sedimentary basin, we interpret that the new basin includes the volcanics and volcaniclastic sequences deposited in the lacustrine environment. This nonmarine basin was possibly formed as the result of the tectonic movement during the Cretaceous, implying the wide occurrence of the Cretaceous basins over the southern Korean Peninsula as well as its southwestern continental shelf.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.2
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• pp.145-152
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• 2024

The present study investigated the digital color characteristics corresponding to different maturity stages and maturation levels of white croaker Pennahia argentatus specimens collected from the Southern Sea of South Korea. Maturity stages were determined using photomicrographs depicting ovarian developmental phases and compared with digital color values. The specimens ranged in body length from 21-36 cm, with mature ovaries observed within the 24-30 cm length range. To differentiate the maturing, mature, spawning, and post-spawning stages of the gonads, boundary lines were established based on specific coordinates. For the ovaries, a dividing line was drawn through (-10, -10) and (15, 5), described by the equation Y=3/5X-4; while for the testes, the line passed through (20, 0) and (0, 15), indicated by the equation Y=-3/4X+15. However, the visual determination of the maturity stages proved challenging due to overlapping color values. Consequently, this study underscores the efficacy of employing digital color measurements over subjective visual assessments to evaluate the maturity of white croaker gonads and offers more quantitative insights.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.1
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• pp.114-128
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• 2019

This study is a spatial analysis of the boundaries related to the division of the Korean peninsula. The boundary space was extracted by extracting $38^{th}$ parallel and digitizing the map of the Armistice Agreement Annex. The purpose of this analysis was to extract more accurate scope based on the armistice agreement, the appendices, and the UNC regulations and to analyze the wrong information correctly. The range of demilitarized zones was determined by UNC 551-4(2014) and UNC 551-5(2015) to ensure that there is no change in the location of the Southern Limit Line. It also confirmed that the MACHA was excluded in the DMZ. As a result, the area of the DMZ was measured at $889.7km^2$. Also this study identified the interval and number of markers in the MDL and the Han River estuary. It could be confirmed that the interval of markers within the MDL depends on the subject of management. This study is more accurate from the start and can be used as basic data needed in the study and education of DMZ and border areas after verification by public organizations.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.27-38
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• 1999

The errors between track segments or at the cross-over points of shipborne gravity were successfully reduced by applying a cross-over error adjustment technique using satellite gravity. The integration of shipborne and satellite altimeter-implied free-air gravity anomalies after the cross-over error adjustment resulted in a high resolution gravity map which contains both short and long wavelength components. The successful adjustment of the cross-over errors in the shipborne gravity using the satellite gravity suggests that the shipborne gravity can be combined with the satellite anomalies characterized by a stable and long wavelength component. The resulting free-air anomaly map is evenly harmonized with both short and long wavelength anomalies. Thus the corrected anomaly map can be better used for the geological interpretation. Free-air anomalies with more than 140 mGal in total variations generally correspond to the seafloor topographic changes in their regional patterns. A series of gravity highs are aligned from the Korea Plateau to the Oki Island, which are interpreted to be caused by seamounts or volcanic topographies. The gravity minima along the western and southern shelf edge are associated not only with the local basement morphology and thick sediment fill at the continental margin, but also possibly with the crustal edge effect known for passive continental margins. Series of NE-trending linear anomalies are possibly caused by a swarm of volcanic intrusions followed the initial opening of the Ulleung Basin. The linear high anomalies in the Ulleung Plateau are terminated by the straightly NNW-trending anomalies with a sharp gradient in its western boundary which indicates a fault-line scarp. The opposite side adjoined with the fault-line scarp shows no correlation with the fault-line scarp in geometry indicating that the block might be horizontally slided from the north. A gravity high in contrast to the deepening in seafloor toward the northeastern central Ulleung Basin is probably responsible for the thin crust and shallow seated mantle. The gravity minima along the western and southern shelf edge are associated not only with the local basement morphology and thick sediment fill at the continental margin, but also possibly with the crustal edge effect known for passive continental margins. Series of NE-trending linear anomalies are possibly caused by a swarm of volcanic intrusions followed the initial opening of the Ulleung Basin. The linear high anomalies in the Ulleung Plateau are terminated by the straightly NNW-trending anomalies with a sharp gradient in its western boundary which indicates a fault-line scarp. The opposite side adjoined with the fault-line scarp shows no correlation with the fault-line scarp in geometry indicating that the block might be horizontally slided from the north. A gravity high in contrast to the deepening in seafloor toward the northeastern central Ulleung Basin is probably suggestive of a thin crust and shallow seated mantle.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.285-296
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• 1998

As a part of the study for understanding the deep geological structure of the Ogcheon Zone, both gravity and geomagnetic surveys are performed. A 70km survey line of which direction is nearly perpendicular to major faults in the southern tip of the Zone. The observed data are corrected and transformed into Bouguer and total magnetic intensity anomalies, respectively. Recent studies for petrology and geochemistry in the southwestern Ogcheon Zone in the vicinity of the survey line are reviewed for better interpretation. Both gravity and geomagnetic anomalies abruptly change around Janghung area, the southern boundary of the, Ogcheon Zone. This rapid increase of Bouguer anomaly around Janghung area can be explained by a deep seated normal fault with fairy large displacement between Precambrian gneisses and the denser intermediate plutonic rocks. It is believed that the fault acted an important role for the formation and evolution of the Ogcheon Zone. A pseudomagnetic intensity anomaly is calculated from the Bouguer anomaly assuming that the both anomalies are associated with the common source. From the origin of the survey line to the 50km point, the calculated anomaly coincides with observed magnetic anomaly. Whereas both anomalies show negative correlation in the outside 50km. From the residual Bouguer anomalies, the subterranean geological structure is provided through the iterative forward method. The initial model is obtained from informations about the surface geology as well as the results of the inverse method.