• Geophysics and Geophysical Exploration
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• v.24 no.2
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• pp.35-44
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• 2021

As the execution speed of Python is slower than those of other programming languages (e.g., C, C++, and FORTRAN), Python is not considered to be efficient for writing numerical geodynamic code that requires numerous iterations. Recently, many computational techniques, such as the Just-In-Time (JIT) compiler, have been developed to enhance the calculation speed of Python. Here, we developed two-dimensional (2D) numerical geodynamic code that was optimized for the JIT compiler, based on Python. Our code simulates mantle convection by combining the Particle-In-Cell (PIC) scheme and the finite element method (FEM), which are both commonly used in geodynamic modeling. We benchmarked well-known mantle convection problems to evaluate the reliability of our code, which confirmed that the root mean square velocity and Nusselt number obtained from our numerical modeling were consistent with those of the mantle convection problems. The matrix assembly and PIC processes in our code, when run with the JIT compiler, successfully achieved a speed-up 30× and 258× faster than without the JIT compiler, respectively. Our Python-based FEM-PIC code shows the high potential of Python for geodynamic modeling cases that require complex computations.

• Journal of the Korean earth science society
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• v.30 no.1
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• pp.111-126
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• 2009

The purpose of this study was to derive the criterions of each type of mental models on the plate boundaries and to investigate high school students' mental models on these concepts. The 11th grade student participants were requested to draw the collisional, convergent, and divergent boundaries and were interviewed individually. The drawings and the data gathered through the interviews were analyzed qualitatively. The mental models on the plate boundaries were classified as 'naive model', 'unstable model', 'causal model', and 'conceptual model'. The criterions for analyzing the mental models were the differentiations of the lithospheric plates and the mantle, the explanations of the motion of the plates and lower mantle, the demonstrations of topographical features of the plate boundaries and the causal relationships between the mantle convection and the topographical features. The findings revealed that the students holding 'the naive model' and 'the unstable model' were unable to relate the mantle convection and the three boundaries. In contrast, the students holding 'the causal model' and 'the conceptual model' were able to explain that the mantle convection causes the three boundaries. Also, the types of epistemological belief were different depending on their mental models. Students holding the naive model and the unstable model tended to rely upon the external authorities.

• Journal of the Korean earth science society
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• v.37 no.1
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• pp.62-77
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• 2016

In the early model of plate tectonics, the plate was depicted as a passive raft floating on the convecting mantle and carried away by the mantle flow. At the same time, ridge push at spreading boundaries and drag force exerted by the mantle on the base of lithosphere were described as the dominant driving forces of plate movements. However, in recent studies of plate tectonics, it is generally accepted that the primary force driving plate motion is slab pull beneath subduction zones rather than other forces driven by mantle convection. The current view asserts that the density contrast between dense oceanic lithosphere and underlying asthenosphere is the substance of slab pull. The greater density of oceanic slab allows it to sink deeper into mantle at trenches by gravitational pull, which provides a dominant driving force for plate motion. Based on this plate tectonics development, this study investigated the contents of plate tectonics in high school Earth Science textbooks and how they have been depicted for the last few decades. Results showed that the early explanation of plate movement driven by mantle convection has been consistently highlighted in almost all high school textbooks since the 5th curriculum, whereas most introductory college textbooks rectified the early theory of plate movement and introduced a newly accepted theory in revised edition. Therefore, we suggest that the latest theory of plate tectonics be included in high school textbooks so that students get updated with recent understanding of it in a timely manner.

• Journal of the Korean Geographical Society
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• v.47 no.3
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• pp.328-346
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• 2012

This study provides quantitative constraints on Neogene uplift in the Korean peninsula using onshore paleo-shoreline records and seismic data. The eastern margin of Northeast Asia including Korea sits in the back-arc system behind the Western Pacific Subduction Zone, a complex trench triple junction of the Philippine Sea, Pacific, and Eurasian (Amurian) plates. An analysis of seismic data in the subduction zone shows that the pattern of uplift in the peninsula mirrors the extent of deep seismicity in subducting Pacific plate beneath. Combined with previous tomographic studies it is proposed that uplift is partly driven by asthenospheric upwelling caused by a sinking slab during the Neogene. In addition, the SHmax orientations of E-W and N-S trends in the peninsula are consistent with the prevailing in-situ stress fields in the eastern Eurasian continent generated by various plate boundary forces. The uplift in Korea during the Late Neogene is attributed, in part, to lithospheric failure relating to faulting movements, thus providing a link between dynamic effects of mantle upwelling at sinking slab edge and lithospheric responses driven by plate boundary forces.

• Economic and Environmental Geology
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• v.4 no.1
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• pp.39-43
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• 1971

The Korean Peninsula is located between the tectonically stable Asian Continent and the tectonically active Japanese islands. The east coast of Korea shows evidence of uplift whereas the west coast shows evidence of submergence. However, radiocarbon dates indicate that the rate of submergence of the west coast of Korea is slower than the tectonically stable east coast of North America. Therefore, both east and west coasts of Korea might have been uplifted during the last post-glacial period. This uplift may result the spreading line of the from compressional strain produced along East Sea of Korea (Japan Sea) and/or the conversion hinge line of the Pacific mantle convection current plunging beneath the Asian continent. This downturn is supposed to be located in the Japan Trench. High heat flow near the east coast of Korea produces the differential strain. This strain accelerates the compressional strain of the peninsula. The Sea Floor Spreading Theory can explain the tectonism of the Korean Peninsula in Recent time. Baek-Doo Mt. and Han-Ra Mt., dormant volcanoes, may be an evidence of westward movement of the Korean Peninsula.

• Journal of the Korean Geographical Society
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• v.49 no.2
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• pp.200-220
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• 2014

This study reexamines the old concept and reviews prevalent statements on Cenozoic vertical motions of the peninsula that have been uncritically repeated in our academia. The contents of this paper are redefinition of the notion, tilted flexure or warping, and a suggestion for a new time set and properties of the deformation, followed by a new model on its influencing factors and processes. In conclusion, the Cenozoic vertical motion of the Korean peninsula can be reified further with an epeirogenic movement of uplift in the east side-subsidence in the west side of the peninsula since the Neogene (23 Ma). However, the regional boundary for areas of uplift and subsidence is not likely in the Korean peninsula but broader farther to East China and the southern part of Russia. It can be best understood that mantle convection produced by subducting activities in the Western Pacific Subduction Zone causes the uplift and subsidence of earth surface around NE Asia. In addition, faultings in the upper lithosphere induced by in-situ plate boundary stresses accelerate regional uplift in the peninsula since the Quaternary. Controversies that are still standing such as current uplift movements along the western coast of the peninsula during the late Quaternary could be precisely discussed with future research providing detailed information on it.

• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.196-202
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• 1996

The effect of cooking(boiling, steaming and baking0and drying on the cholesterol content and formation of oxidized cholesterols in quid(Japanese flying squid, Todarodes pacificus) was studied. Cholesterol content of live squid meat varied with the portion sampled, and results from spectrophotometric assay ranged from 263.2mg/1..g(mantle) to 315.8mg/100g(tentacle). The cholesterol levels analyzed by gas chromatography(GC) for squid samples were lower by 7% of total cholesterol for live squid meat and 24% for processed meat than those results by spectrophotometric assay. Cooking resulted in the decrease of the initial total cholesterol content of raw meat from 10%(boiling for 5min.) to 25%(steaming for 5min.) The amounts of cholesterol remaining after baking were 68% for microwave oven samples and 64% for convection oven samples. Drying of raw tissue caused the greater reduction in cholesterol content than cooking but showed no significant difference in samples stored for 6 weeks at 4$^{\circ}C$ and 2$0^{\circ}C$. Raw squid meats contained essentially no oxidized cholesterols, while the 22-hydroxychoesterol was detected in frozen meats. The additional oxidized cholesterols as cholestane-triol was indentified with 22-hydroxycholesterols in cooked samples. Sun dried meat stored at 4一 and 2$0^{\circ}C$ for 6 weeks had the three kinds of oxidized cholesterols such as 22-hydroxycholesterol, cholesta-3,5-dien-7-one and cholestane-triol.

• Journal of the Korean Society of Earth Science Education
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• v.1 no.1
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• pp.111-118
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• 2008

This study is aimed at analyzing earth conception the nine pre service teachers who are majoring in earth science education and classifying a special feature from the ontological categories. Open ended questionnaires and semi structured interviews which meant to contribute to identifying ontological categories of concepts involving study area were designed. Pre service teachers' ontological category about earth conception most showed to dynamic and proto process. In the results show that many pre service teachers recognize simply the conception to a material, a condition and a conversion of the state changing. Most of the pre service teachers show their intermediate understanding level about the earth inner construction according to the analyzed results of the drawing tasks and interviews. The main alternative conceptions show them through a definition of the plate, a wording definition between lithosphere and asthenosphere, a feature of the plate boundary, a heat convection in the earth inner, the earth inner heat source, the earth inner structure, a physical feature of the mantle.

• Journal of the Korean Society of Food Culture
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• v.17 no.4
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• pp.465-472
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• 2002

The effect of cooking(boiling, steaming and baking) and drying on the cholesterol content and formation of oxidized cholesterols and acid value in squid(Japanese flying squid, Todarodes pacificus) was studied. Cholesterol content of live squid meat varied with the portion sampled. The data from spectophotometric assay ranged from 263.2 mg/100g(mantle) to 315.8 mg/100g(tentacle). The cholesterol levels found for squid samples analyzed by gas chromatography(GC) were lower by 7% of total cholesterol for live squid meat and 24% for processed meat than those results by spectrophotometric assay. Cooking resulted some decrease in the initial total cholesterol content of raw meat from 10%(boiling for 5 min.) to 25%(steaming for 5 min.). The amounts of cholesterol remaining after baking were 68% for microwave oven samples and 64% for convection oven samples. Drying of raw tissue caused the greater reduction in cholesterol content than cooking but brought about no significant difference in samples stored for 6 weeks at $4^{\circ}C\;and\;20^{\circ}C$. Raw squid meats contained essentially no oxidized cholesterols, while the 22-hydroxychoesterol was detected in frozen meats. The additional oxidized cholesterols as cholestane-triol was indentified with 22-hydroxycholesterol in cooked samples. Sun dried meat stored at $4^{\circ}C\;and\;20^{\circ}C$ for 6 weeks had the three kinds of oxidized cholesterols such as 22-hydroxycholesterol, cholesta-3,5-dien-7-one and cholestane-triol. For the boiled and steamed squids, 10% higher acid value and 5% higher acid value respectively were observed but oven cooked samples resulted in a 50% higher acid value than raw samples. Squids had a 45% higher acid value than raw one during sundrying and presrevation at $20^{\circ}C$ but there was not a severe difference of acid value between $4^{\circ}C\;and\;20^{\circ}C$ stored samples.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.53-53
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• 2010

지표위의 어떤 지점에서의 지구자기의 수평분력 방향과 진북방향 사이의 각을 편각(Declination)이라고 정의한다. 쉽게 말하면 편각은 나침반의 자침이 가러 키는 방향과 진북방향과의 사이 각을 말한다. 대부분의 사람들은 나침반의 자침이 북자기극(North magnetic pole)을 가러킨다고 잘못알고 있다. 지구 다이나모설(Geodynamo theory)에 의하면 주로 철(약 90%)로 구성된 외핵 속에서 계속 생성 유지되고 있는 복잡한 (각각 나선형(helical)의 회전축에 대체로 평행하거나 평행하지 않은) 대류(Convection currents)에 수반하는 전류가 복잡한 지구자기장을 형성한다. 지표상에서 측정한 지구자기장의 자료를 Spherical harmonic analysis 으로 분석하면 한 개의 커다란 쌍극자(Dipole) (Inclined geocentric dipole 또는 주된 자기장(Main field) 이라고 부름), 적도쌍극자(Equatorial dipole), 4극자 (Quadrupoles), 8극자(Octupoles) 등의 여러 개의 크고 작은 쌍극자들의 총합이 지구자기장의 근원인 것처럼 해석되고 있다. 어떤 지점에서의 지구자기장의 방향은 외핵에서 생성된 천체 자기장에서 Main field를 제거한 나머지 자기장과, 상부 맨틀(upper mantle), 지각 및 지표상에 존재하는 인공 물체 또는 암석 및 광석 등의 잔류자기 및 유도자기 그리고 지형 등의 영향으로 결정된다. 어떤 지점에서의 지구자기장의 방향은 태양풍(Solar wind)과 전리층 사이의 상호작용 등의 외부자장(external field)의 영향도 받는다. 비쌍극자 자장(Non-dipole field)은 지표상에서 측정되는 총자기장에서 외핵에서 생성된 주된 자기장(Main field) 즉, 지구의 회전축에서 약 11.5도 기울어진 쌍극자 자장을 제거하고 남는 자기장을 말한다. 따라서 편각은 비쌍극자자장의 영향을 가장 많이 받는다. 비쌍극자 자장은 정지한 상태의 자장(standing field) 과 매년 서쪽으로 약 0.2도 움직이는 Westward drift하는 자장으로 크게 두 가지로 구분된다. 쌍극자 자장의 방향은 매우 느리게 변하지만 그 세기는 현재 비교적으로 빠르게 약해지고 있다. 비교적으로 매우 빠르게 변하는 비쌍극자 자장의 변화를 영년변화(Secular variation) 이라고 한다.