• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.197-202
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• 2015

Numerous challenges in treating permanent dentition are encountered, especially in treating immature teeth with pulp necrosis. Historically, calcium hydroxide application during long periods of time was used to induce the formation of a calcific barrier across the open apex. In 2004, a new treatment modality for the management of the open apex was introduced. This treatment was named as 'revascularization' and gained acceptance among dentists. The protocol was different from the traditional apexification techniques in that the canal was irrigated and disinfected with a combination of three antibiotics (ciprofloxacin, metronidazole and minocycline). At the next appointment, bleeding was induced and the canal was sealed with MTA. Successful regenerative endodontic treatment of necrotic immature permanent teeth can provide continued root development, increased thickness in the dentinal walls and apical closure. These developments of a functional pulp-dentin complex have a promising impact on retaining the natural teeth, the goal of the dental health care.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.237-243
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• 2014

The environmental problem is serious due to global warming In a concrete industry, the effort to reduce the problem of the destruction of environment arising from the indiscriminate use of limestone that is the raw material of cement and aggregate and the exhaustion of resources are continually emphasized In this research, the waste porcelain and waste glass that are the natural aggregate substitute materials were mixed and were applied. In addition, the magnesia phosphate composite and fly ash are mixed with a cement substitute material and the properties of the artificial stone was examined. Density, water absorption, rate of aggregate on the surface, compressive strength, and flexural strength were performed. As a result of the test, it is that waste glass with 60% and waste porcelain with 70% are the most excellent mix to produce the artificial stone.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.273-288
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• 2011

Chon-Ashuu copper mining claim area is located, in terms of the geotectonic setting, in the northern part of the suture line which is bounded with the marginal part of Issik-kul micro-continent on the southern part of North Tien-Shan terrane. The geological blocks of Chon-Ashuu districts belong to the southern tip of Kazakhstan orocline. The rock formation of this area are composed of the continental crust or/and arc collage and the paleo-continental fragments-accretionary wedge complex of pre-Altaid orogenic materials. ASI(Alumina Saturation Index) of Paleozoic plutonic rocks in Chon-Ashuu area belong to the peraluminous and metaluminous rocks which were generated from fractional crystallization of Island and volcanic arc crusts in syn-post collisional plate. The geology of the ChonAshuu area consists of upper Proterozoic and Paleozoic rock formations. According to Harker variation diagrams for Chon-Ashuu arenaceous sedimentary rocks, the silty sandstone of Chon-Ashuu area showing the mineralogical immaturity were derived from Island arc or the marginal environments of active continent in Cambro-Carboniferous period. Numerous intrusive rocks of Chon-Ashuu area are distributed along north east trending tectonic structures and are bounded on four sides by the conjugate pattern. The most common type of the plutonic rocks are granodiorite and monzodiorite. According to the molecular normative An-Ab-Or composition (Barker, 1979), the plutonic rocks in Chon-Ashuu area are classified into tonalite - trondhjemite - granodiorite (TTG) series which are an aggregation of rocks which is the country rock of copper mineralization, that are formed by melting of hydrous mafic crust at high pressure.

• The Journal of the Petrological Society of Korea
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• v.9 no.2
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• pp.53-69
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• 2000

To reveal the origin of the Chuncheon nephrite deposit, radiogenic isotopes of Sr and Pb, stable isotopes of 0 and H, and rare earth elements concentrations were analyzed. Such geochemical data were integrated to track the stepwise changes during the various ore formation stages. All the samples from the nephrite deposit have significantly low 0 isotopic ratios compared with the marble from which they had been formed, which reflects the very important role of the crustal circulating water with low 6180 and 6D in every stage of ore formation. There were progressive decrease of 6180 and 6D during the genesis of Chuncheon nephrite deposit. Newly formed minerals during the ore formation reveal disequilibrium with existing minerals in the respect of 0 isotope, which suggests that the ore-forming fluid of circulating water origin was involved with significant water-rock ratios in every step of ore formation process. The ore samples have Sr and Pb isotopic ratios similar to the values of Kyeonggi gneiss complex within which the deposit is located, which also suggests the important role of crustal circulating water in the genesis of the deposit. In conclusion, all the geochemical data support that major portion of the ore-forming fluid of Chuncheon nephrite deposit was derived ultimately from the surface water of meteoric origin. The meteoric water supplied Sr and Pb through leaching the rocks surrounding the ore deposits.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.317-333
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• 2012

The Yeongweol Group is a Lower Paleozoic mixed carbonate-siliciclastic sequence in the Taebaeksan Basin of Korea, and consists of five lithologic formations: Sambangsan, Machari, Wagok, Mungok, and Yeongheung in ascending order. Sequence stratigraphic interpretation of the group indicates that initial flooding in the Yeongweol area of the Taebaeksan Basin resulted in basal siliciclastic-dominated sequences of the Sambangsan Formation during the Middle Cambrian. The accelerated sea-level rise in the late Middle to early Late Cambrian generated a mixed carbonate-siliciclastic slope or deep ramp sequence of shale, grainstone and breccia intercalations, representing the lower part of the Machari Formation. The continued rise of sea level in the Late Cambrian made substantial accommodation space and activated subtidal carbonate factory, forming carbonate-dominated subtidal platform sequence in the middle and upper parts of the Machari Formation. The overlying Wagok Formation might originally be a ramp carbonate sequence of subtidal ribbon carbonates and marls with conglomerates, deposited during the normal rise of relative sea level in the late Late Cambrian. The formation was affected by unstable dolomitization shortly after the deposition during the relative sea-level fall in the latest Cambrian or earliest Ordovician. Subsequently, it was extensively dolomitized under the deep burial diagenetic condition. During the Early Ordovician (Tremadocian), global transgression (viz. Sauk) was continued, and subtidal ramp deposition was sustained in the Yeongweol platform, forming the Mungok Formation. The formation is overlain by the peritidal carbonates of the Yeongheung Formation, and is stacked by cyclic sedimentation during the Early to Middle Ordovician (Arenigian to Caradocian). The lithologic change from subtidal ramp to peritidal facies is preserved at the uppermost part of the Mungok Formation. The transition between Sauk and Tippecanoe sequences is recognized within the middle part of the Yeongheung Formation as a minimum accommodation zone. The global eustatic fall in the earliest Middle Ordovician and the ensuing rise of relative sea level during the Darrwillian to Caradocian produced broadly-prograding peritidal carbonates of shallowing-upward cyclic successions within the Yeongheung Formation. The reconstructed relative sea-level curve of the Yeongweol platform is very similar to that of the Taebaek platform. This reveals that the Yeongweol platform experienced same tectonic movements with the Taebaek platform, and consequently that both platform sequences might be located in a body or somewhere separately in the margin of the North China platform. The significant differences in lithologic and stratigraphic successions imply that the Yeongweol platform was much far from the Taebaek platform and not associated with the Taebaek platform as a single depositional system. The Yeongweol platform was probably located in relatively open shallow marine environments, whereas the Taebaek platform was a part of the restricted embayments. During the late Paleozoic to early Mesozoic amalgamations of the Korean massifs, the Yeongweol platform was probably pushed against the Taebaek platform by the complex movement, forming fragmented platform sequences of the Taebaeksan Basin.