• Journal of the Mineralogical Society of Korea
• /
• v.13 no.2
• /
• pp.96-114
• /
• 2000

춘천 연옥은 색깔에 따라 세가지 유형 (연녹색, 암녹색, 및 회색 연옥)으로 구분되고 이들은 각기 서로 다른 조직과 조성을 나타낸다. 연녹색 연옥이 이중에서 가장 일반적인 유형이다. 연옥은 주로 극미립의 연옥질 투각섬석으로 구성되고 여기에 미량의 휘석, Mg-녹니석 및 방해석이 불순물로서 수반된다. 연옥질 투각섬석 결정들은 그 폭이 5$\mu\textrm{m}$ 이하의 극미립질 침상 결정형을 이루며 서로 치밀하게 얽혀있는 연옥 특유의 조직을 나타낸다. 주사전자현미경 하에서 (110)의 벽개면의 발달이 현저하고, 주사탐침현미경 하에서는 벽개면을 가로지르는 방향으로 특징적인 조선이 나타나는 것이 특징이다. 연옥질 투각섬석은 투과전자현미경 하에서 흔히 단쇄형과 복쇄형이 결합한 3중쇄형 격자가 복쇄형의 투각섬석 구조 내에서 불규칙적으로 협재되는 혼성격자 구조가 발달하는 것이 특징이다. 드물지만 5중쇄형 격자와 4중쇄형 격자도 관찰되는데, 이 같은 불규칙한 격자 혼재상은 회색 연옥에서 보다 현저한 경향을 보인다. 이와 같은 혼성격자 구조형의 존재는 춘천 연옥이 열역학적으로 비평형 상태에서 형성되었음을 시사하는 것으로 여겨진다. 리트벨트법에 의한 구조검증을 통해서 구해진 연옥질 투각섬석들의 격자상수 값들은 X-선회절의 경우, a=9.837(1)~9.9804(4)$\AA$, b=18.046(2)~18.062(1)$\AA$. c=5.2765(7)~5.2803(3)$\AA$, $\beta$=104.717(9)~104.786(3)$^{\circ}$로 계산되었다. 이에 비해서 중성자 회절법에 의해서 측정되 격자 상수 값은 a=9.8841(6)~9.8933(7)$\AA$, b=18.1429(7)~18.161(2)$\AA$, c=5.3024(3)~5.3060(7)$\AA$, $\beta$=104.698(7)~104.771(4)$^{\circ}$로서 X-선회절에 의한 값들과 약간의 차이를 보인다. 연옥질 투각섬석은 Ca에 대한 Mg의 치환에 의해 M(4) 자라의 크기가 작아지면서 b축의 단위포도 함께 줄어드는 결정화학적 특징을 나타낸다. 이는 중성자 회절분석에 의해서 구해진 M(4)의 자리점유율과 M(4)-O의 원자간 거리에 의해서도 확인된다. 그러나 연옥질 투각섬석에 대한 리트벨트법에 구조검증 결과는 연옥의 유형별 미시적 광물상과 혼성격자 구조형의 특징에 별다른 연계성이 없는 것으로 나타났다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.6
• /
• pp.325-331
• /
• 2022

Hydrogen embrittlement in metals has been a serious issue with regard to structural safety. In this study, molecular dynamics simulations revealed that the aggregation of hydrogen atoms at the crack tips suppresses the dislocation emission and thus results in cleavage fracture. A series of molecular dynamics simulations were performed considering factors such as the concentration of hydrogen atoms, loading rate, and diffusion coefficient. We investigated the conditions that minimize hydrogen embrittlement. The simulation results were consistent with the experimental results and used to quantify hydrogen embrittlement.

• The Journal of the Petrological Society of Korea
• /
• v.23 no.2
• /
• pp.105-117
• /
• 2014

The Ogcheon and Joseon Supergroups are distributed in the Bonghwajae area, Jecheon-si, Chungcheongbuk-do, Korea which is located in the northeastern fore-end of the Ogcheon Metamorphic Zone. This paper researched the geological structures based on the geometric and kinematic characteristics and the forming sequence of the major multi-deformed rock and microstructures. Most of regional foliations are not the S0 bedding but the S0-1 composite foliations defined by the preferred orientation of stretching minerals, some are recognized as the S0-1-2 composite foliations by the preferred orientation of insoluble opaque minerals and cleavage lamella. The geological structures were formed at least by three phases of deformations i.e. NNE-SSW trending D1, E-W trending D2, N-S trending D3 compressions. The S0-1 composite foliation, which shows a similar zone-distribution trend of the constitution strata of the Ogcheon and Joseon Supergroups, trended WNW before D2 deformation, but it was reoriented into N-S which was parallel to the trend of S2 foliation by D2 deformation, and it was rearranged into NW, NE, N-S trends as it is now by D3 deformation. The structural characteristics of each deformation phase and the deformation history are very similar to those in the eastern domain of Busan area into which the Ogcheon and Joseon Supergroups in this area are extended as NNW trend. It is expected to be very valuable data in interpreting the tectonic evolution of the northeastern fore-end of the Ogcheon Metamorphic Zone.

• Economic and Environmental Geology
• /
• v.15 no.1
• /
• pp.41-47
• /
• 1982

Typical stratigraphic sequences of Paleozoic form the Baegunsan Syncline (equal to Hambaeg Syncline) and Taebaegsan Group is the basement in the southern part of Kangweon Province. Deformation pattern depends on their stratigraphic site and their internal properties. In the biotite schists and meta-sandstones of Pre-Cambrian sequences, flow folds and ptygmatic folds are developed, and high strain deformation is pervasive. Deformational patterns of Cambro-Ordovician are variable because of their various formations. Fracturing is pervasive in the Jangsan Quartzite and Daegi and Maggol Limestone. Welldeveloped slaty cleavage and angular folds of kink and chevron types are the prevailing structures of pelitic rocks. The most characteristic feature of limestone alternated with argillite is the "Compositional cleavage (Author's proposal)" known as the "Worm-eatern" structures. It was known that this structures have a sedimentary origin. But their preferred orienation of long axis of erosional lime holes, originated from tectonic deformation of folding. And this structures have the same character as the axial plane cleavages. Fracturing and long wave concentric folds are dominant characters of the Upper Paleozic sequences. In this area, two folds are superimposed. Field studying and analysis of structures show that the cross-folds of NS-direction are pervasive and were deformed by the EW-directional Baegunsan Syncline. The cross-folding is the major and penetrative deformation and prior to Baegunsan Syncline.