• Journal of the Mineralogical Society of Korea
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• v.3 no.1
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• pp.18-33
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• 1990

각종 콘크리트 구조물의 기초공사에서 생기는 문제점 외에 시멘트와 골재자체의 반응, 즉 알카리-골재반응에 의한 물리, 화학적인 변화가 구조물에 피해를 주는 일차적인 요인으로 작용된 사례가 최근 10년간 외국에서는 잇달아 보고 되고 있다. 국내산 콘크리트 구조물에 대한 본 연구에 의하면 변성작용을 받은 이축성 석영, 자아석류가 시멘트로부터 공급된 알카리용매에 쉽게 반응, 붕괴되며 조립질보다 세립질 골재에 더 큰 영향이 나타난다. 골재와 시멘트 사이의 반응에 의하여 K, Na, Ca 및 Si 성분이 함량이 높은 부분으로부터 낮은 곳으로 상호 치환 이동되는데 그 과정에서 smectite와 illite같은 점토광물이 반응생성물로 정출된다. 이러한 광물은 구조물 내에서 수분의 흡수와 방출에 의하여 부피의 팽축이 거듭됨으로써 콘크리트 구조물에 심각한 손상을 야기시킨다.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.423-435
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• 2001

The gold-silver vein deposits in the Mugeug mineralized area are emplaced in late Cretaceous biotite granite associated with the pull-apart type Cretaceous Eumseong basin. Mugeug mine in northern part is composed of multiple veins showing relatively high gold fineness and is characterized by sericitization, chloritization and epidotization. The ore-forming fluids were evolved by dilution and cooling mechanisms at relatively high temperature and salinity (=30$0^{\circ}C$,1~9 equiv. wt. % NaCl) and highly-evolved meteoric water ($\delta$$^{18}$ O;-1.2~3.7$\textperthousand$) and gold mineralization associated with sulfides tormed at temperatures between 260 and 22$0^{\circ}C$ and within sulfur fugacity range of 10$^{-11.5}$ ~ 10$^{-13.5}$ atm. In contrast, Geumwang, Geumbong and Taegueg mines show the low fineness values, in southern part are characterized by increasing tendency of simple and/or stockwork veins and by kaolinitization, silicificatitan, carbonatization and smectitization. These droposits formed at relatively low temperature and salinity (<23$0^{\circ}C$, <3 equiv. wt. % NaCl) from ore-forming fluids containing greater amounts of less-evolved meteoric waters ($\delta$$^{18}$ O;-5.5~4.0$\textperthousand$), and silver mineralization representing various gold-and/or silver-bearing minerals formed at temperatures between 200 and 15$0^{\circ}C$ and from sulfur fugacity range of 10$^{-15}$ ~10$^{-18}$ atm These results imply that mineralization in the Mugueg area formed at shallow-crustal level and categorize these deposits as low-sulfidation epithermal type. The genetic differences between the northern and southern parts reflect the evolution of the hydrothermal system due to a different physicochemical environment from heat source area (Mugeug mine) to marginal area (Taegeum mine) in a geothermal field.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.403-414
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• 1995

The purpose of this study was to investigate the histologic changes in mandibular periodontium during overbite closure for openbite treatment by continuous arch wires and anterior vertical elastics. Two female monkey(Macaca nemestrina) with permanent dentition were used. Posterior bite block was fixed to each of their maxillae, which made the animal temporary anterior openbite as well as stabilized the whole maxillary anchorage. In each mandible, all the teeth except the second molars which had been extracted, were prepared for cast crowns. 018 inch Standard brackets were welded on these crowns. After cementation, two types of the $016{\times}022$ inch continuous arch wires, the plain ideal arch to the control animal and the MEAW(multiloop edgewise archwire) to the other experimental one were inserted. Then anterior vertical elastics were applied for two weeks. The overbite depth changes in the monkeys and histologic examinations of the mandibular periodontiums suggested the following conclusions. 1. During two weeks of the experimental period, the overbite increased + 0.3 mm in the control and + 1.3 mm in the experimental one. 2. In both the control and the experimental animal, histologic examinations showed that incisors, canines and first premolars were subject to extrusive force and the rest of posteriors were subject to intrusive one. 3. In periodontiums of the extruded incisors of the experimental one, reorientation of the periodontal fiber structures reflected the direction of force and the alveolar bone surfaces including apical and crestal areas which had been subject to tension, were the front of new bone formation. 4. In periodontiums of the extruded incisors of the experimental one, neither excessive hyalinization nor gross root resorption was observed. 5. Alveolar bone remodeling of anteriors and posteriors was more remarkable in the experimental one than the control.

• The Journal of the Petrological Society of Korea
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• v.6 no.3
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• pp.185-209
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• 1997

Granitic rocks in the Cheongsan area cosist of three plutons-Baegrog granodiorite, Cheongsan porphyritic granite, and two mica granite. Amphilboles from the Baegrog granodiorite belong to the calcic amphilbole group and show compositional variations from magnesio-hornblende in the core to actinolitic hornblende in the rim. Biotites from the three granites represent intermediate compositions between phlogopite and annite. Muscovites from the two mica granite are considered to be primary muscovite in terms of the occurrence and mineral chemistry. Each granitic rock reveals systematic variation of major oxide contents with $SiO_2$. Major oxide variation trends of the Baegrog granodiorite are fairly different from those of Cheongsan porphyritic granite and two mica granite. The latter two granitic rocks are also different with each other in variation trends for some oxides. Thus three granitic rocks in the Cheongsan area were solidifield from the independent magmas of chemically different, heterogeneous origin. The granitic rocks in the area show calc-alkaline nature. The whole rock geochemistry shows that the Baegrog granodiorite and Cheongsan porphyritic granite belong to metaluminous, I-type granite, whereas the two mica granite to peraluminous, I/S-type granite. The opaque mineral contents and magnetic susceptibility represent that the granitic rocks in the area are ilmenite-series granite, indicating that each magma was solidified under relatively reducing environment. The tectonic environment of the granitic activity in the area seems to have been active continental margin. Alkali feldspar megacryst in the Cheongsan porphyritic granite is considered to be magmatic, judging from the crystal size, shape, arrangement, and distribution pattern of inclusions. The petro-graphical characteristics of the Cheongsan porphyritic granite can be explained by two stage crystallization. Under the smaller degree of undercooling the alkali feldspar megacrysts rapidly grew owing to slow rate of nucleation and fast growth rate. At the larger degree of undercooling the nucleation rate and density drastically increased and the small crystals of the matrix were formed.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.17-32
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• 1982

The Wolak tungsten-molybdenum deposits are tungsten-molybdenum bearing quartz veins which filled the fractures in Pre-Cambrian pebble-bearing calcareous hornfels, hornfels and Cretaceous granite. There are two vein groups in this mine, Dongsan vein group in the west and Kwangcheon vein group in the east. The ore minerals are wolframite, scheelite, molybdenite, native bismuth, bismuthinite, pyrite, arsenopyrite, chalcopyrite, cubanite, stannite, pyrrhotite, sphalerite, galena, marcasite, Pb-Bi sulfosalt and ilmenite. Quartz, calcite, beryl, fluorite, muscovite, rhodochrosite and siderite are gangue minerals. Fluid inclusion studies were carried out for the quartz, beryl, scheelite, early and late fluorite. Fluid inclusion studies reveal that liquid-gas inclusions are most common and occur in all of the minerals examined. Filling degree of the inclusions in the late fluorite is much higher than that of the inclusions in quartz and early fluorite. Liquid $CO_2$ bearing liquid-gas inclusions occur in quartz and early fluorite. Liquid, gas and solid phase inclusions occur in quartz, beryl and scheelite. Salinities of inclusions in quartz and beryl from Dongsan vein group range from 3.9 to 8.0, from 5.3 to 7.7 wt.% NaCl equivalent respectively. Salinities in the late fluorite range from 1.5 to 3.2 wt.% NaCl equivalent. In Kwangcheon vein group salinities range from 3.9 to 9.6 wt.% NaCl equivalent in quartz, from 2.8 to 7.3 wt.% NaCl equivalent in early fluorite, from 1.3 to 1.5 wt.% NaCl equivalent in late fluorite. Homogenization temperatures of inclusions range from $239^{\circ}$ to higher than $360^{\circ}C$ in quartz, over $360^{\circ}C$ in scheelite, from $288^{\circ}C$ to higher than $360^{\circ}C$ in beryl, and from $159^{\circ}$ to $202^{\circ}C$ in late fluorite of the Dongsan vein group. In Kwangcheon vein group, homo genization temperatures of inclusions range from $240^{\circ}C$ to higher than $360^{\circ}C$ in quartz and from $240^{\circ}$ to $328^{\circ}C$ in early fluorite. As a whole, in Dongsan and Kwangcheon vein groups it seems that there are no distinct differences in mineralogy, salinities and homogenization temperatures. No distinct variations in homogenization temperatures are revealed through about 300 m vertically in both district. The faint trend of increase in salinities in the lower level can be detected. The salinity, $CO_2$ content and the temperature of ore fluid were much higher in the early vein stage and then dropped off in the late stage of mineralization as represented by the quartz and fluorite inclusion data.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.47-59
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• 2016

Purpose: The aim of this study was to investigate the changes in occlusal force after loss of the lower first molar depending on the inclination and extrusion of the adjacent and opposing teeth by using a strain gauge. Materials and Methods: Anatomic teeth were used to reconstruct the normal dental arch with loss of the lower right first molar. A uniformly thick layer of silicone was applied to the root to mimic the periodontal ligament. Four stages of dies with varying degrees of inclination and extrusion of the adjacent and opposing teeth were constructed and attached to master model interchangeably by using a CAD/CAM fabricated customized die system. The strain gauges were attached to teeth and a universal testing machine was used to determine the changes in occlusal force. An independent t-test and one-way ANOVA were performed (${\alpha}=.05$). Results: While simulating chewing food, the upper first, second premolar and lower second molar showed greater occlusal force than before extraction. When the change of adjacent teeth's occlusal force with their progressive movement after molar loss was evaluated, the difference among four die models was significant and was in the decreasing aspect (P < 0.05). Conclusion: When the lower first molar was lost and the adjacent teeth did not move yet, the occlusal force in adjacent teeth was higher than that when the lower first molar still existed. In addition, the occlusal force in the upper premolars and lower second molar decreased significantly with the progressive movement of adjacent teeth.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.215-232
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• 2020

The study area of Nokjeonri in Yeongwol belongs to the Taebaeksan Mineralized District. Ca and Mg skarn and related ore mineralization are developed in the Pungchon formation along the contact with the Imog granite. Ca skarn hosted in limestone mostly comprises garnet and pyroxene. Mg skarn developed in dolomite includes olivine and serpentine. Magnetite-hematite and pyrrhotite(±scheelite)-pyritegalena-sphalerite were mineralized during early and late stage, respectively. Garnet compositions are dominated by andradite series in proximal area and grossular series in distal area. Pyroxene compositions correspond to diopside series in majority. These compositional changes indicate that the fluids varied from oxidizing condition to reducing condition due to increased reaction with carbonated wall rocks as the fluids moved from the granite to a distal place. Fe₂O₃ and MgO concentrations of magnetite are higher in Mg skarn than those in Ca skarn, while FeO shows opposite trend. The Zn/Fe ratio of sphalerite increases with distance from the Imog granite. The δ³⁴S values of sulfide minerals are similar to those of the Imog granite, indicating magmatic origin in ore sulfur. Mineralization was established in the order of skarn, oxide and sulfide minerals with decreasing temperature and oxygen fugacity and increasing sulfur fugacity.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.40-49
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• 2018

It is reported that the causes of unaesthetic proportion of anterior teeth vary widely. Especially, when the unaesthetic tooth proportion of the mandibular incisors arises due to the wear of the anterior teeth accompanied by the compensation of the alveolar bone, it may cause serious functional and aesthetic problems. In such case, it should be considered that the evaluation of vertical dimension and tooth proportion as well as smile line, soft tissue and hard tissue morphology. And, increase of vertical dimension or clinical crown lengthening followed by prosthodontic restorations is needed to improve the interdental mesial/distal, width/length ratio considering the anterior guidance. This case report demonstrates functional and aesthetic improvements through systematic diagnosis and treatment procedures in a 48-year-old male patient with unaesthetic anterior teeth proportion because of tooth wear accompanied by the compensation of alveolar bone and defect of several central incisors due to chronic periodontitis.

• Economic and Environmental Geology
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• v.43 no.5
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• pp.477-490
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• 2010

The Gagok stratabound skarn deposit is the result of the intrusion of the Cretaceous granitic pluton into the Paleozoic calcareous rocks. The subvolcanic intrusion ranges in composition from quartz monzonite to granite porphyry with I-type, calc-alkaline and weakly peraluminous characteristics. Both endoskarn and exoskarn are developed at the Gagok Zn-(Pb) deposit, with more exoskarn than endoskarn. Geochemical and mineralogical characteristics in the Seongok and Wolgok orebodies can be treated in terms of self-organization. Sphalerites in the Gagok ore can also incorporate minor amounts of Mn, Cd, Cu and In. Trace element concentrations in different orebodies vary because fractionation of a given element into sphalerite is influenced by formation temperature and the amount of sphalerite in the ore. A group of high In/Zn and Cd/Zn ratios in ores, and low Mn/Fe ratios in sphalerites are correlated with proximal processes of a magmatic source. The pattern of minor/trace element variations in ores and sphalcrites can be used for petrogenetic interprctation, e.g., orebody zonation related to crystallization temperature and fluid d sources.

• The Journal of the Petrological Society of Korea
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• v.9 no.2
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• pp.70-83
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• 2000

The purpose of this study is to identify the petrographic and geochemical characteristics of four granitic masses and clanfy for the origin and relationship among the masses. These granitic rocks are distributed in the eastern part of Yangsan fault in the Kyongsang basin, southeastern part of Korea. Based on the mineralogy and texture, the granitic rocks are divided into three facies; granodiorite, porphyritic fine-grained granite, and equigranular granite. According to the result of modal analysis, northern part and most of the southern part of Daebon granitic rocks are plotted in granodiorite field and the rest part of the xocks are plotted in granite field. These granitic rocks belong to the sub-alkaline series, and are subdivided into calc-alkaline series. The rare earth elements normalized bv chondrite show LREE is more enriched than HREE and the lowest values in O-w m- i t e and Daebon equigranular granite. The crystallization pressures and temperatures of minimum melt compositions of granitic rocks estimated from the study area are about 0.5-1 kbar and $700~820^{\circ}C$, respectively. Referring to the petrographic characteristics, geochemical data and radiogenic age data, Oyu granite was emplaced in the Paleocene, but Daebon granodiorite, Sanseo porphyritic granite, and Hoam equigranular granite are co-magmatic differentiation products, were emplaced in the Eocene.