• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.235-253
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• 2006

We interpreted marine seismic profiles in conjunction with swath bathymetric and magnetic data to investigate rifting to breakup processes at the Korean margin leading to the separation of the Japan Arc. The Korean margin is rimmed by fundamental elements of rift architecture comprizing a seaward succession of a rift basin and an uplifted rift flank passing into the slope, typical of a passive continental margin. In the northern part, rifting occurred in the Korea Plateau, a continental fragment extended and partially segmented from the Korean Peninsula, that provided a relatively broader zone of extension resulting in a number of rifts. Two distinguished rift basins (Onnuri and Bandal Basins) in the Korea Plateau we bounded by major synthetic and smaller antithetic faults, creating wide and symmetric profiles. The large-offset border fault zones of these basins have convex dip slopes and demonstrate a zig-zag arrangement along strike. In contrast, the southern margin is engraved along its length with a single narrow rift basin (Hupo Basin) that is an elongated asymmetric half-graben. Rifting at the Korean margin was primarily controlled by normal faulting resulting from extension in the west and southeast directions orthogonal to the inferred line of breakup along the base of the slope rather than strike-slip deformation. Although rifting involved no significant volcanism, the inception of sea floor spreading documents a pronounced volcanic phase which seems to reflect slab-induced asthenospheric upwelling as well as rift-induced convection particularly in the narrow southern margin. We suggest that structural and igneous evolution of the Korean margin can be explained by the processes occurring at the passive continental margin with magmatism intensified by asthenospheric upwelling in a back-arc setting.

• The Journal of the Petrological Society of Korea
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• v.18 no.1
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• pp.19-30
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• 2009

The main fault of Yangsan Fault Zone (YFZ) and Quaternary fault were found in a trench section with NW-SE direction at an entrance of the Sinheung village in the northern Eonyang, Ulsan, Korea. We interpreted the movement history of the southern part of the YFZ from the geometric and kinematic characteristics of basement rock's fault of the YFZ (Sinheung Fault) and Quaternary fault (Quaternary Sinheung Fault) investigated at the trench section. The trench outcrop consists mainly of Cretaceous sedimentary rocks of Hayang Group and volcanic rocks of Yucheon Group which lie in fault contact and Quaternary deposits which unconformably overlie these basement rocks. This study suggests that the movement history of the southern part of the YFZ can be explained at least by two different strike-slip movements, named as D1 and D2 events, and then two different dip-slip movements, named as D3 and D4 events. (1) D1 event: a sinistral strike-slip movement which caused the bedding of sedimentary rocks to be high-angled toward the main fault of the YFZ. (2) D2 event: a dextral strike-slip movement slipped along the high-angled beddings as fault surfaces. The main characteristic structural elements are predominant sub-horizontal slickenlines and sub-vertical fault foliations which show a NNE trend. The event formed the main fault rocks of the YFZ. (3) D3 event: a conjugate reverse-slip movement slipped along fault surfaces which trend (E)NE and moderately dip (S)SE or (N)NW. The slickenlines, which plunge in the dip direction of fault surfaces, overprint the previous sub-horizontal slickenlines. The fault is characterized by S-C fabrics superimposed on the D2 fault gouges, fault surfaces showing ramp and flat geometry, asymmetric and drag folds and collapse structures accompanied with it. The event dispersed the orientation of the main fault surface of the YFZ. (4) D4 event: a Quaternary reverse-slip movement showing a displacement of several centimeters with S-C fabrics on the Quternary deposits. The D4 fault surfaces are developed along the extensions of the D3 fault surfaces of basement rocks, like the other Quaternary faults within the YFZ. This indicates that these faults were formed under the same compression of (N)NW-(S)SE direction.

• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.43-52
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• 2000

Hemifacial microsomia ( HFM ) is the second most common craniofacial abnormalies. HFM represnted a spectrum of clinical findings such as hypoplasia of the mandibular ramus and condyle, confinement of maxilla growth, external and/or middle ear defects, involvement of some cranial suture, buccal soft tissue, facial nerve, and muscles in the affected side. HFM often showed progressive facial asymmetry and occlusal plane slanting to the affected side with growth. There were several reports about asymmetry of tooth maturation, hypodontia, delayed eruption, enamel hypoplasia in HFM. Since teeth develope in close association with size and morphology of the maxillary and the mandible, it is highly likely that dental changes will be present in HFM. So the Purpose of this study was to investigate the differences of the primary and the permanent teeth dimensions in the maxillary and the mandibular dentition between the affected and the non-affected side of HFM.. The sample of this study consisted of 34 unilateral HFM Patients (18 males and 16 females, average age : 5 year 11 months old). The authors examined the mesiodistal and the faciolingual dimensions of the primary and the permanent teeth and performed statistical study by using paired t-test. The results were as follows 1. The mesiodistal dimensions of the mandibular second primary molar and the mandibular first permanent molar in the affected side of HFM were significantly smaller than those of non-affected side. But there were no significant differences in the anterior teeth and the mandibular first primary molar. It means that a gradient of severity from anterior teeth to posterior teeth was found in the mandibular dentition. 2. Although there were no significant differences in the faciolingual dimensions of the primary and the permanent teeth in the maxillary and the mandibular dentition between the affected and non-affected side of HFM, there were general trend of compensatory increase in faciolingual dimension of the mandibular primary and the permanent teeth in the affected side Therefore these results showed that HFM might affect on the abnormality of tooth dimension, especially the most posterior teeth, in the affected side of the mandible.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.234-249
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• 2002

The Miwon-Boeun area in the central and northern part of Okcheon metamorphic zone, Korea, is composed of Okcheon Supergroup and Mesozoic Cheongju and Boeun granitoids which intruded it. The Okcheon Supergroup consists mainly of quartzite (Midongsan Formation), meta-calcareous rocks (Daehyangsan Formation, Hwajeonri Formation), meta-psammitic rocks (Unkyori Formation), meta-politic rocks (Munjuri Formation), meta-conglomeratic rocks (Hwanggangni Formation) in the study area, showing a zonal distribution of NE trend. Its' general trend is locally changed into NS to EW trend in and around high-angle fault of NS or NW trend. This study focused on deformation history of the Okcheon Supergroup, suggesting that the geological structure was formed at least by four phases of deformation. (1) The first phase of deformation occurred under ductile shear deformation of top-to-the southeast movement, forming sheath fold or A-type fold, asymmetric isoclinal fold, NW-SE trending stretching lineation. (2) The second phase of deformation took place under compression of NW-SE direction, forming subhorizontal, tight upright fold of M trend in the earlier phase, and formed semi-brittle thrust fault (Guryongsan Thrust Fault) of top-to-the southeast movement and associated snake-head fold in the later phase. (3) The third phase of deformation formed subhorizontal, open recumbent fold through gravitational or extensional collapses which might be generated from crustal thickening and gravitational instability. (4) The fourth phase of deformation formed moderately plunging, steeply inclined kink fold related to high-angle faulting, being closely connected with the local change of NE-trending regional foliation into NS to EW direction of strike in the vicinity of the high-angle fault.

• Radiation Oncology Journal
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• v.5 no.1
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• pp.13-21
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• 1987

The effect of local hyperthermia of 41 to $43^{\circ}C$ for 30 minutes on radiosensitivity of normal tissue was studied utilizing jejunal crypt microcolony assay. Hyperthermia of this range enhanced the radiation effect and the effect was mainly additive without significant effect on the slopes of cell survival curves. At the isoeffect level of 20 microcolony formation, the thermal enhancement ratio was 1.02, 1.10 and 1.39 for $41^{\circ},\;42^{\circ}\;and\;43^{\circ}C$, respectively. The distribution of microcolony formation along the circumference of jejunum was not uniform, having more colonies around the mesenteric border, and this suggests the effect of uneven cooling by blood circulation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.214-220
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• 2001

The clinical application of the three-dimensional radiographic technique had been limited to standard Broadbent-Bolton cephalometer with biplanar stereoradiography. We developed a new method for compensating the error of head position in ordinary non-biplanar cephalostat. It became to possible to use the three dimensional cephalogram commonly in clinical bases. 1. The method of methemetical compensation of head positioning error in non-biplanar condition was evaluated with dry skull. The error of the method of first and the second trial was $0.46{\pm}1.21$, $0.33{\pm}0.90mm$, which means the error of the head positioning correction in conventional cephalogram was within clinical acceptance. 2. The reproducibility of this system for clinical application was 0.54 mm ($-2.99{\sim}2.26mm$) which defines the absolute mean difference of the first and second trial. Compare to the The landmark identification error $1.2{\pm}1.6mm$, the error of the measurement was within the range of landmark identification error. The result indicates the adequate clinical accuracy of the computation of three-dimensional coordinates by compensation of the error of the head position in ordinary non-biplanar cephalostat.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.240-251
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• 2008

Objective: The purpose of this study was to evaluate the effect of head position changes on the root parallelism between adjacent teeth on panoramic radiographs. Methods: A model with normal occlusion was constructed in the SolidWorks program, then RP (rapid protyping) model was fabricated. The model was repeatedly imaged and repositioned five times at each of the following nine positions: ideal head position, $5^{\circ}$ up, $10^{\circ}$ up, $5^{\circ}$ down, $10^{\circ}$ down, $5^{\circ}$, right, $10^{\circ}$, up, and $5^{\circ}$ right rotation, $10^{\circ}$ right rotation. Panoramic radiographs were taken by Planmeca ProMax and the angle between the long axes of adjacent teeth was directly measured in the monitor. Results: Axes of adjacent teeth tended to converge toward the occlusal plane when the head tilted up and converged in the opposite direction to the occlusal plane when the head tilted down. Anterior teeth showed the most notable differences. When one side of the head tilted up $5^{\circ}$ and $10^{\circ}$ along the anteroposterior axis (Y axis), tooth axes of the same side tended to converge toward the occlusal plane and tooth axes of the opposite side tended to converge in the opposite direction to the occlusal plane. When the head rotated to one side along the vertical axis (Z axis), the canine and lateral incisor of the same side converged in the opposite direction to the occlusal plane and the canine and lateral incisor of the other side converged toward the occlusal plane. Conclusions: When assessing the root parallelism on panoramic radiographs, the occlusal plane cant (anteroposterior or lateral) or asymmetry of the dental arch should be considered because these can cause distortion of tooth axes on panoramic radiographs.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.203-213
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• 2024

This study aimed to investigate the seasonal patterns of multiple bar formation in summer and flattening in winter on the macrotidal Sinduri beach in Taean, and to understand the processes their formation and subsequent flattening. Beach profiling has been conducted regularly over the last four years using a VRS-GPS system. Surface sediment samples were collected seasonally along the transectline, and grain size analyses were performed. Tidal current data were acquired using a TIDOS current observation system during both winter and summer. The Sinduri macrotidal beach consists of two geomorphic units: an upper high-gradient beach face and a lower gentler sloped intertidal zone. High berms and beach cusps did not develop on this beach face. The approximately 400-m-wide intertidal zone comprises distinct 2-5 lines of multiple bars. Mean grain sizes of sand bars range from 2.0 to 2.75 phi, corresponding to fine sands. Mean sizes show shoreward coarsening trend. Regular beach-profiling survey revealed that the summer profile has a multi-barred morphology with a maximum of five bar lines, whereas, the winter profile has a non-barred, flat morphology. The non-barred winter profiles likely result from flattening by scour-and-fill processes during winter. The growth of multiple bars in summer is interpreted to be formed by a break-point mechanism associated with moderate waves and the translation of tide levels, rather than the standing wave hypothesis, which is stationary at high tide. The break-point hypothesis for multi-bars is supported by the presence of the largest bar at mean sea-level, shorter bar spacing toward the shore, irregular bar spacing, strong asymmetry of bars, and the 10-30 m shoreward migration of multi-bars.