• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.184-193
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• 2024

Harbor and Fishery Design Criteria defines that ship routing should be designed to ensure safe ship navigation and easy maneuvering. The design of the channel width is one of the critical conditions in routeing of ships. For the criteria of the channel width, qualitative evaluation criteria are used in South Korea, whereas quantitative evaluation criteria are used in other countries. Environmental factors, such as winds, tidal currents, and waves directly or indirectly affect ship resistance when sailing. Depending on their strength the environmental factors may pose a threat to the safe navigation of ships. Thus, vessel traffic control was regulated in South Korea according to the Beaufort scale. In order to design the channel width to reflect the environmental factors closely related to the safe navigation of ships, quantitative evaluation criteria reflected with environmental factors were presented in other countries, however, these external factors were not considered in South Korea. This study analyzed the relationship between the channel width actually used by ships and environmental factors by using the trajectories of ships entering and leaving Mokpo Port. This study also suggested the required channel width according to tidal currents and compared it with the channel width design criteria of other countries.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.635-646
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• 1995

Mineralized zone in the Dongyang talc deposits occurs on the lowest dolomite member of the Hyangsanri Dolomite belonging to the Ogcheon Supergroup. Ore bodies are emplaced as pipe-like body along the axis of minor folds plunging $40^{\circ}$ to the west developed in these dolomite layers. Amphibolite and chlorite schist are found along the upper or lower contact of all ore bodies (Kim et al., 1963; Park and Kim, 1966). Following the recrystallization and silicification of dolomite, tremolite and tabular and leafy talc(I) of the earlier stage formed, and microcrystalline talc(II) formed in the later stage. Talc(l) and tremolite formed by the reaction between dolomite and the fluid. Whereas talc (II) formed by the reaction between dolomite and fluid, or by the reaction between early formed tremolite and fluid. During the early stage of mineralization, the fluid was the $H_2O-CO_2$ system dominant in $CO_2$, In the later stage, the composition of the fluid changed to $H_2O-NaCl-CO_2$system, and finally to the $H_2O-NaCl$ system. The pressure and temperature conditions of the formation of tremolite associated with talc(I) were 1,640~2,530 bar, and $440{\sim}480^{\circ}C$, respectively. The pressure and temperature condition of talc(II) ore formation was 1,400~2,200 bar, and $360{\sim}390^{\circ}C$, respectively. These conditions are much lower than the metamorphic pressure and temperature of the rocks from the Munjuri Formation located about 5 km to the noJ:th of Dongyang talc deposit ${\delta}^{13}C$ and ${\delta}^{18}O$ values of dolomite which is the host rock of the talc ore deposit are 2.9~5.7‰ (PDB), and -7.4~l6.8‰ (PDB), respectively. These values are little higher than those from the Cambro-Ordovician limestones of the Taebaeksan region, but belong to the range of the unaltered sedimentary dolomite. ${\delta}^{18}O$and ${\delta}D$ values of the talc from Dongyang deposit are 8.6~15.8‰ (vs SMOW), and -65~-90‰ (vs SMOW), respectively, belonging to the range of magmatic origin. These values are quite different from those measured in the metamorphic rocks of Munjuri and Kyemyungsan Formation. ${\delta}^{34}S$ value of anhydrite is 22.4‰ (CDT), which is much lower than ${\delta}^{34}S$ (30‰ vs COT) of sulfate of early Paleozoic period, and indicates the possibility of the addition of magmatic sulfur to the system. Talc ores show the textures of weak foliation and well developed crenulation cleavages. Talc ore deposit in the area is concluded as hydrothermal replacement deposit formed before the latest phase of the deformations that Ogcheon Belt has undergone.

• The Journal of the Petrological Society of Korea
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• v.8 no.2
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• pp.106-124
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• 1999

In the Cheongju-Minwon area which occupies the middle part of the Ogcheon Metamorphic Belt, three metamorphic events(M1, M2, M3) had occurred. Intermediate P/T type M2 regional metamorphism formed prevailing mineral assemblages in the study area. Low PIT type M3 contact metamorphism occurred due to the intrusion of granites after M2 metamorphism. M1 metamorphism is recognized by inclusions within garnet. During M2 metamorphism, the metamorphic grade increased from the biotite zone in the southeastern part to the garnet zone in the northwestern part of the study area. This result is similar to the metamorphic evolution of the southwestern part of the Ogcheon Metamorphic Belt. Garnets in the garnet zone are classified into two types; Type A garnet has inclusions whose trail is connected to the foliation in the matrix and Type B garnet has inclusion rich core and inclusion poor rim. Type A garnet formed in the mica rich part with crenulation cleavage whereas Type B garnet formed in the quartz rich part with weak crenulation cleavage. In some outcrops, two types garnets are found together. Compared to the rim of Type A garnet, the rim of Type B garnet is lower in grossular and spessartine contents but higher in almandine and pyrope contents. In some Type B garnets, the inclusion poor part is rimmed by muddy colored or protuberant new overgrowth. In the inclusion poor part and new overgrowth, a rapid increase in grossular and decrease in spessartine is observed. However, the compositional patterns of Type A and B are similar; Ca increases and Mn decreases from core to rim. Two types garnets formed mainly due to the difference of bulk chemistry instead of metamorphic and deformational differences. The metamorphic P-T conditions estimated from Type A garnets are 595-690 OC15.7-8.8 kb, which indicates M2 metamorphism is intermediate P/T type metamorphism. On the other hand, a wide range of P-T conditions is calculated from Type B garnets. The P-T conditions from most Type B garnet rims are 617-690 OC16.2-8.9 kb which also indicates an intermediate P/T type metamorphism. However, at the rim part with flat end or weak overgrowth, grossular content is low and 573-624OC14.7-5.8 kb are estimated. The P-T conditions calculated from plagioclase and biotite inclusions in garnet are 460-500 0C/1.9-3.0 kb. The P-T conditions from rim part with weak overgrowth and inclusions within garnet, indicate that low P/T type M1 regional metamorphism might have occurred before intermediate P/T type M2 regional metamorphism. The P-T conditions estimated from samples which had undergone low PIT type M3 metamorphism strongly, are 547-610 0C/2.1-5.0 kb.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.492-501
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• 2007

Coastal disasters have become one of the most important issues in every coastal country. In Korea, coastal disasters such as storm surge, sea level rise and extreme weather have placed many coastal regions in danger of being exposed or damaged during subsequent storms and gradual shoreline retreat. A storm surge is an onshore gush of water associated with a tow pressure weather system, typically in typhoon season. However, it is very difficult to predict storm surge height and inundation due to the irregularity of the course and intensity of a typhoon. To provide a new scheme of typhoon damage prediction model, the scenario which changes the central pressure, the maximum wind radius, the track and the proceeding speed by corresponding previous typhoon database, was composed. The virtual typhoon scenario database was constructed with individual scenario simulation and evaluation, in which it extracted the result from the scenario database of information of the hereafter typhoon and information due to climate change. This virtual typhoon scenario database will apply damage prediction information about a typhoon. This study performed construction and analysis of the simulation system with the storm surge/coastal inundation model at Masan coastal areas, and applied method for predicting using the scenario of the storm surge.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.628-636
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• 2018

Because large buoys are mainly made of steel, they are heavy and vulnerable to corrosion by sea water. This makes buoy installation and maintenance difficult. Moreover, vessel collision accidents with buoys and damage to vessels due to the material of buoys (e.g., steel) are reported every year. Recently, light buoys adopting eco-friendly and lightweight materials have come into the spotlight in order to solve the previously-mentioned problems. In Korea, a new lightweight buoy with a 7-Nautical Mile lantern adopting expanded polypropylene (EPP) and aluminum to create a buoyant body and tower structure, respectively, was developed in 2017. When these light buoys are operated in the ocean, the visibility and angle of light from the lantern installed on the light buoys changes, which may cause them to function improperly. Therefore, research on the performance of light buoys is needed since the weight distribution and motion characteristics of these new buoys differ from conventional models. In this study, stability estimation and motion analyses for newly-developed buoys under various environmental conditions considering a mooring line were carried out using ANSYS AQWA. Numerical simulations for the estimation of wind and current loads were performed using commercial CFD software, Siemens STAR-CCM+, to increase the accuracy of motion analysis. By comparing the estimated maximum significant motions of the light buoys, it was found that waves and currents were more influential in the motion of the buoys. And, the estimated motions of the buoys became larger as the sea state became worser, which might be the reason that the peak frequencies of the wave spectra got closer to those of the buoys.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.143-156
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• 2014

We reviewed investigation status on turbidity plume in the statement of marine environmental survey(2008 to 2012) associated with marine sand extraction projects. The survey statement from seven marine sand extraction sites (extraction area of Southern EEZ, extraction area of Western EEZ, relocation zone in the Western EEZ, sea area under jurisdiction of Taean-gun, sea area under jurisdiction of Ansan City, and two discrete sea areas under jurisdiction of Ongjin-gun) in the nearshore and offshore of Korea showed that in situ observations were carried out for the dispersion and transport of suspended sediments on two areas (One is a extraction area in the EEZs, the other is an area of coastal sites). However, sampling station and range have not been selected considering physical, geographical factors (tide, wave, stratification, water depth, etc.) and weather conditions (wind direction and velocity, fetch, duration, etc). Especially turbidity plumes originating from three sources, which include suspended sediments in overflow(or overspill) discharged from spillways and reject chutes of dredging vessel, and resuspended sediments from draghead at the seabed, may be transported to a far greater distance outside the boundary of the extraction site and have undesirable impacts on the marine environment and ecosystem. We address that behaviour of environmental pollutants such as suspended solids, nutrients, and metals should be extensively monitored and diagnosed during the dispersion and transport of the plume. Finally we suggest the necessity to supplement the current system of the sea area utilization consultation and establish the combined guidelines on marine sand extraction to collect basic data, to monitor cumulative effects, and to minimize environmental damages incurred by the aftermath of sand extraction.

• Journal of the Korean association of regional geographers
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• v.6 no.2
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• pp.83-96
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• 2000

Erosional basins formed in middle and upper reaches of Korean great rivers have been main life space of local small and middle cities, but previous studies on erosional basins are widely apart from residents' life and are in shortage with the endeavor to elucidate the man and environment relationship. This paper analyzes the factors and the modes of land-use changes of hills in the erosional basin. In this paper four erosional basins with different geological conditions are selected to elucidate the effect of geological factor(Geochang: granite, Chogye: metamorphic rock, Angye: gravelly sedimentary rock, Maseong: limestone). And the distribution of land use on the transverse and longitudinal cross-section map of the hill is described. The landscape of erosional basin is consisted of surrounding mountains, hills, dissected valleys, and incoming river's floodplain. Dissected valleys and incoming river's floodplain were reclaimed early as paddy field and hills have been used as woodland up to recently. Residents have a new appreciation of hills as a productive hill out of a traditional holy space[mountain] by influence of capitalistic thought that 'natural environment is a sort of productive resource'. Population increase is the another pressure of hill reclamation. The modes of landscape changes due to natural conditions are as follow: (1) In Geochang basin with dense tectolineament spacing, the gentle part of hill is used as field, orchard and agricultural-industrial complex site and the steep part is as woodland. (2) Hills in Angye basin with sparse tectolineament spacing are relatively flat because of maintaining a part of original denudational surface, and are used as orchids, field, paddy fields and agricultural-industrial complex site. The dissection valleys between hills are gentle concave and are used as paddy fields. (3) Hills in Maseong basin are wide and flat, and are used as fields, orchards, and agricultural-industrial complex site. (4) Because hills in Chogye basin, a closed type, are weared by affluents and are narrow and short. Hills are used as woodland and wide dissected valleys are reclaimed as paddy fields.

• Korean Journal of Heritage: History & Science
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• v.47 no.2
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• pp.46-67
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• 2014

The Dinosaur track-bearing deposits recently found at Bangudae Petroglyph site in Ulju (National Treasure No. 285) have been studied in the aspects of sedimentology, paleoenvironments, and significance in natural history. The dinosaur tracks occur in the Daegu Formation (late Early Cretaceous), and over 80 footprints including 43 ornithopod footprints, 36 sauropod footprints, and 2 theropod footprints are preserved in this tracksite. The track-bearing deposits consist of irregularly interlaminated siltstone and mudstone, calcareous sandy to silty mudstone, thin-bedded tuffaceous sandstone, planar- to cross-laminated sandstone, and thin- to medium-bedded graded sandstone, and they are interpreted to be sheetflood deposits on an alluvial plain. Diverse types of ripples and mudcracks, rainprints, and invertebrate trace fossils are observed in these deposits, and the crest-lines of wave ripples do not show preferred orientation. Dinosaur footprints occur as true prints, underprints, overtracks, and casts on the bedding surfaces, and the orientation of trackways are scattered. It is interpreted that paleoclimatic condition of the track-bearing deposits were semiarid with alternation of wetting and drying periods, and that dinosaurs frequented small and shallow ponds during wetting periods and recorded their tracks on an alluvial plain. The frequent occurrence of dinosaur tracks in study area indicates that the Cretaceous deposits around Daegokcheon Stream are very useful sedimentological and paleontological records to understand the paleoecology and paleoenvironments during the dinosaur age in Korean Peninsula. Consequently the dinosaur track-bearing deposits around Daegokcheon Stream should be further studied in sedimentary geology and paleontology in order to enhance cultural heritage value of the Petroglyphs of Bangudae Terrace as the World Heritage.