• Economic and Environmental Geology
• /
• v.57 no.1
• /
• pp.1-15
• /
• 2024

The Melanesian region in the western Pacific is dominated by complex plate tectonics, with the largest oceanic plateau, the OntongJava plateau, and a hotspot, the Caroline Islands. To better understand the complex geodynamics of the region, we estimate P- and S-velocity models and 𝛿 (V_P/V_S) model by using relative teleseismic travel times measured at seismometers on land and the seafloor. Our results show high-velocity anomalies in the subduction zones of the Melanesian region to a depth of about 400 km, which is thought to be subducting Solomon Sea, Bismarck, and Australian plates along plate boundaries. Along subduction zones, positive 𝛿 (V_P/V_S) anomalies are found, which may be caused by partial melting due to dehydration. A broad high-velocity anomaly is observed at 600 km depth below the Ontong-Java plateau, with a negative 𝛿 (V_P/V_S) anomaly. This is thought to be a viscous and dry remnant of the Pacific plate that subducted at 45-25 Ma, with a low volume of fluids due to dehydration for a long period in the mantle transition zone. Beneath the Caroline Islands, a strong low-velocity anomaly is obseved to a depth of 800 km and appears to be connected to the underside of the remnant Pacific plate in the mantle transition zone. This suggests that the mantle plume originating in the lower mantle has been redirected due to the interaction with the remnant Pacific plate and has reached its current location. The mantle plume also has a positive 𝛿 (V_P/V_S) anomaly, which is thought to be due to the influence of embedded fluids or partial melting. A high-velocity anomaly, interpreted as an effect of the thick lithosphere beneath the Ontong-Java plateau, is observed down to 300 km depth with a negative 𝛿 (V_P/V_S) anomaly, which likely indicate that little fluid remains in the melt residue accumulated in the lithosphere.

• Journal of the Korean earth science society
• /
• v.39 no.2
• /
• pp.193-207
• /
• 2018

The purpose of this study was to analyze trends in conceptual change research in the field of Earth Science education conducted in Korea and to provide them as basic data of future concept change research. The trends of conceptual change research were analyzed in terms of keywords, year of publication, source of research, purpose of research, subject, area of research, and research method. This study was carried out on a total of 126 conceptual change papers of Earth Science education published from 1989 to July 2017. This study showed the following conclusions: First, the conceptual change research papers used more the term 'conceptual change' than 'misconceptions' and 'preconceptions'. Second, the conceptual change paper has achieved a large amount of growth in the 2000s. Third, conceptual change research tended to proceed to the subject of master's dissertation. Fourth, there were a lot of researches to find out the misconceptions and change them into the right concept, the conceptual change paper used free response test for misconceptions, and cognitive conflict instruction model and CAI (Computer Assisted Instruction) teaching strategy for misconceptions. Fifth, elementary school students were studied the most. Sixth, the study of conceptual changes in the field of Earth Science was high in the astronomical and atmospheric areas. Finally, although quantitative analysis methods were used in the early days of research, in the 2010s, qualitative analysis methods were widely used. In this paper, we proposed research on conceptual change for pre- and in-service teachers, expansion of research on conceptual changes in various fields such as geology, oceanography, atmosphere in Earth Science, investigation of causes of misconception in Earth Science and research on individual's affective factors, and so on.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_1
• /
• pp.481-493
• /
• 2017

Estuary sand bar of Namdaecheon Stream is located in Yangyang-gun, Gangwon-do in Korea. This unique place is situated between end of Namdaecheon Stream and East Sea. It is an important environment area of the global ecosystem from the transition zone of land and marine environments by forming a variety of coastal circumstance. Some endemic species should be protected which is appearing in the Namdaecheon Stream because of preservation for future generations. Especially, the salmon return to this stream as adults in order to breed which is more than 70 % of the salmon in Korea peninsular. The monitoring of estuary sand bar is need to analyze ecological environment and sustainable development with time. First of all we represents a different shape of estuary sand bar of Namdaecheon Stream from 1984 to 2015 using Landsat satellite imagery series. Particularly movement of the "tidal inlet" is most important factor to investigate the condition of the change for estuary sand bar. The location of tidal inlet is compared with precipitation, height of tide and oceanic current data according to time variation.

• Korean Journal of Microbiology
• /
• v.47 no.1
• /
• pp.22-29
• /
• 2011

Rhodopsin is a membrane protein with seven transmembrane region which contains a retinal as its chromophore. Although there have been recently reports on various photo-biochemical features of rhodopsins by a wide range of purifying and measurement methods, there was no actual comparison related to the difference of biochemical characteristics according to their physical environment of rhodopsins. First, proteorhodopsin (PR) was found in marine proteobacteria whose function is known for pumping proton using light energy. Second one is Anabaena sensory rhodopsin (Nostoc sp.) PCC7120 (ASR) which belongs to eubacteria acts as sensory regulator since it is co-expressed with transducer 14 kDa in an operon. In this study, we applied two types of rhodopsins (PR and ASR) to various environmental conditions such as in Escherichia coli membranes, membrane in acrylamide gel, in DDM (n-dodecyl-${\beta}$-D-maltopyranoside), OG (octyl-${\beta}$-D-glucopyranoside), and reconstituted with DOPC (1,2-didecanoyl-sn-glycero-3-phosphocholine). According to the light-induced difference spectroscopy, rhodopsins in 0.02% DDM clearly showed photointermediates like M, and O states which respond to the different wavelengths, respectively and showed the best signal/noise ratio. The laser-induced difference spectra showed the fast formation and decay rate of photointermediates in the DDM solubilized samples than gel encapsulated rhodopsin. Each of rhodopsins seemed to be adapted to its surrounding environment.

• Journal of the Korean earth science society
• /
• v.31 no.7
• /
• pp.785-797
• /
• 2010

This study identified the linguistic features of Earth science treatises through the analysis of the register. Data included three Korean treatises that were in geology, atmospheric science, and oceanography. The register of Earth science treatise was as follows: First, there were semantic, referential connections between Themes and Rhemes, that the messages and main points of the texts were expressed coherently and cohesively. Second, some predicates were used which were related to deductive inference, abductive inferences, or causal relation according to the genre elements of each text. The logical relations were not represented by the conjunctions but by the types of predicates. Third, most texts in the treatises showed interpersonally weak relationship using mental predicates related to possibilities, which meant scientists expressed indirectly their interpretation, explanation, or arguments. From these results, we argued that some activities of unpacking the language of science be included in science curriculum in order to improve students' literacy of science texts and understanding scientists' knowledge construction.

• Journal of the Korean earth science society
• /
• v.36 no.6
• /
• pp.520-532
• /
• 2015

In order to understand the Holocene sea level changes in the eastern Yellow Sea, the west coast of Korea, and to compare the rates of sea level rise in each period of time, the geological proxy records for pre-instrumental era and measurement data for the present day were combined and analysed. The sea level in the Yellow Sea rose fast with a rate of about 10 mm/yr during the early Holocene, and decelerated down to 1 mm/yr since the mid to late Holocene. The rising rates of sea level in the 20th century were slightly higher than those in the late Holocene. The present-day rates of sea level rise, known as the 'rapid' rise, are in fact much lower or similar, compared to the early to mid Holocene sea levels in the study area. Recent tide-gauge data show that sea level rise in the eastern Yellow Sea has been accelerating toward the 21st century. These rising trends coincide well with global rising patterns in sea level. Additionally, the present-day rising trends of sea level in this study are correlated with increased rates of carbon dioxide concentrations and sea surface temperatures, further indicating a signal to global warming associated with the human effect. Thus, the sea level changes induced by current global warming observed in the eastern Yellow Sea and world's oceans can be considered as 'Anthropocene' sea level changes. The changes in sea level are based on instrumental measurements such as tide-gauges and satellite altimetry, meaning the instrumental era. The Holocene changes in sea level can thus be reconstructed from geological proxy records, whereas the Anthropocene sea-level changes can be solely based on instrumental measurements.

• The Korean Journal of Petroleum Geology
• /
• v.7 no.1_2 s.8
• /
• pp.19-27
• /
• 1999

Korea, an energy-resources-poor country, imports $100{\%}$ of its, oil and, natural gas supply, which accounts for the greater part of its total primary requirements. One of the important task of the government is diversification of available energy resources such as oil and natural gas. Natural gas hydrate, which is non-conventional types of natural gas, distributes worldwide, especially in marine and permafrost. It would become a target of natural gas resources in the near future. Especially sigrificant amount of hydrates are expected to be located in the East Sea around Korea Peninsular. This paper describes about a multi-year overall project framework of basic research and technological development of natural gas hydrate in Korea focused on the interpretation of the seismic survey, the characteristics and physical properties of the natural gas hydrate, and the utilizable technology of natural gas hydrates from the status of research and development of the world.

• Journal of the Korean Geophysical Society
• /
• v.9 no.4
• /
• pp.443-453
• /
• 2006

Using seismic profiles obtained in the Antarctic Peninsula continental margin around Smith Island located at the southwestern end of the South Shetland Islands, we investigated sediments distribution, sedimentation, continental shelf formation, and tectonic evolution history. The study area is a very unique area that has two tectonic provinces with a tectonic boundary near Smith Island just the landward projection of the Hero Fracture Zone (HFZ). To the southwest of the Island, the margin became inactive margin after the collision of the ridge crest of the Antarctic-Phoenix ridge and trench, whereas to the northeast the margin is still apparently active margin with the spreading center and trench morphology in the sea. Generally the northeastern margin has the shelf sedimentary basins wth thick sedimentary layers, well-developed forearc basin, broad continental slope and distinct trench morphology, and the southwestern margin is characterized by steep and narrow continental slope and localized shelf basins. the mid-shelf basement high structures are distinct in the southwestern margin, which are thought to be formed by thermal effect caused by the subducted spreading centers. The high is observed in the area just northeast of the Island, implying that the tectonic boundary along the landward projection of the HFZ is not sharply defined.

• Journal of the Korean earth science society
• /
• v.28 no.2
• /
• pp.147-158
• /
• 2007

The purpose of this study was to investigate research trends of Japanese earth science education published in Chigakukyouiku by the Japan Society of Earth Science Education. A total of 129 articles published in the Journal between 1998 and 2003 were analyzed. The Journal published six issues each year, and each issue contained about four articles that were fewer numbers than Journal of the Korean Earth Science Society's. About Sixty percent of the papers were written by a single author. Analyzing the content of the papers, it was noted that the most articles were geology-related (41.1%) followed by oceanography-related (1.6%) and general science education papers (1.6%). In summary, the characteristics of research trends of Japanese earth science education are as follows: First, the most topics of the papers were related to environmental sciences including earthquake, volcano, and tsunami. This trend seems natural because Japanese schools are situated within the reach of these environmental events. Second, there found many papers that dealt with geological field trip or fossils adjacent to the local community. Third, there were several papers that established a relationship between environmental education and earth science education. Obviously these papers tried to incorporate environmental education into earth science education at the school level. Last but not least, there found an effort to introduce computer into earth science education as an innovative educational method, for example, 'computer and earth science education'.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.3
• /
• pp.333-341
• /
• 2014

Since distribution and preservation of cultural artifacts in the submarine sediments are directly affected by not only ocean currents and tides, but also their composition, it is very important to investigate geological characteristics of sediments and ocean-sediment interactions for maritime archaeological survey. Physical properties of submarine sediments, which are collected by grab sampler and vibro-corer, are analyzed in order to investigate effects of submarine environment on development of maritime archaeological survey techniques. Result of physical property analysis showed that bulk density, shear strength, and magnetic susceptibility increase with depth, while water contents and porosity decrease with depth. Since the magnetic susceptibility of bedrock is about 40 times that of submarine sediments, it might impact greatly on the response of magnetic survey. Physical properties of sediments with depth and sediment classification by Folk's ternary diagram indicate that submarine sediment mainly consists of silt, and cultural artifacts can not penetrate no deeper than 1.5 m in sediments.