• Economic and Environmental Geology
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• v.41 no.1
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• pp.1-14
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• 2008

The Bongsang gold-silver deposit consists of quartz veins that fill along the fault Bone within Cretaceous andesitic lapilli tuff. Mineralization is occurred within fault-breccia zones and can be divided into two stages. Stage I which can be subdivided into early and late depositional stages is main ore mineralization and stage II is barren. Stage I began with deposition of wall-rock alteration minerals and base-metal sulfides, and was deposited by later native silver, Ag-bearing tetrahedrite, polybasite and base-metal sulfides such like pyrite, sphalerite, chalcopyrite and galena. Fluid inclusion data indicate that homogenization temperatures and salinities of stage I range from 137 to $336^{\circ}C$ and from 0.0 to 10.6 wt.% NaCl, respectively. It suggests that ore forming fluids were cooled and diluted with the mixing of meteoric water. Also, temperature and sulfur fugacity deduced mineral assemblages of late stage I are $<210^{\circ}C\;and\;<10^{-15.4}$ atm, respectively. Sulfur(3.4%o) isotope composition indicates that ore sulfur was mainly derived from a magmatic source as well as the host rocks. The calculated oxygen{2.9%o, 10.3%o(quartz: 7.9%o, 8.9%o, calcite: 2.9%o, 10.3%o)}, hydrogen(-75%o) and carbon(-7.0%o, -5.9%o) isotope compositions indicate that hydrothermal fluids may be meteoric origin with some degree of mixing of another meteoric water for paragenetic time.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.41-54
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• 1993

The Ulsan Fe-W deposit, which can be classified as a calcareous skarn deposit, is represented by ore pipe consisting principally of magnetite and lesser amounts of scheelite with minor sulphides, sulphosaits, arsenides, sulpharsenides, etc. At Ulsan mine, metasomatic processes of skarn growth may be divided broadly into two stages based on the paragenetic sequence of calc-silicate minerals and their chemical composition; early and late skarn stages. Early stage has started with the formation of highly calcic assemblages of wollastonite, diopsidic clinopyroxene and nearly pure grossular, which are followed by the formation of clinopyroxenes with salite to ferrosalite composition and grandite garnets with intermediate composition. Based on these calc-silicate assemblages, the temperatures of early skarn formations have been in the ranges of $550^{\circ}$ to $450^{\circ}$. The calc-silicate assemblages formed during the earlier half period of late skarn stage show the enrichment of notable iron and slight manganese, and the depletion of magnesium; clinopyroxenes are hedenbergitic, and grandite garnets are andraditic. The formation temperatures during this skarn stage are inferred to have been in the range of $430^{\circ}$ to $470^{\circ}C$ at low $X_{CO_2}$ by data from fluid inclusions of late andraditic garnets. The later half period of late skarn stage is characterized by the hydrous alteration of pre-existing minerals and the formation of hydrous silicates. The main iron-tungsten mineralization representing prominent deposition of magnetite immediately followed by minor scheelite impregnation has taken place at the middle of early skarn stage, while complex polymetallic mineralization has proceeded during and after the late skarn stage. Various metals and semimetals of Fe, Ni, Co, Cu, Zn, As, Mo, Ag, In, Sn, Sb, Te, Pb and Bi have been in various states such as native metal, sulphides, arsenides, sulphosaits, sulpharsenides and tellurides.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.157-162
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• 2002

The efficient timer-controlled irrigation and the favorable fruiting position were investigated far highly quality melon fruits from Feb.18 to July Si 1999. The nutrient solution was supplied either at every hour from 6：00 to 18：00 (T-1) or at 6：00, 8：00, 10：00, 11：00, 12：00, 12：30, 13：00, 13：30, 14：00, 14：30, IS：00,16：00, and 17：00 (T-2). A fruit was set at the first node of the fruit bearing branch from the 10, 12, or 13th node of the main stem. Pot weight was maintained at almost n constant level, regardless of the daily integrated solar radiation in T-2. Soluble solids content (SSC) and fresh weight of fruit were not significantly different among the irrigation treatments at each harvesting time. At the first harvest, SSC and fresh weight of fruit were not significantly different between the fruiting positions within the irrigation treatment. At the second harvest, SSC was higher in T-2 than T-1. The SSC was low in the fruit of the loth node in T-1, while it was not significantly different between fruiting positions in T-2. Fruit fresh weight was the highest at the 12 and 13th nodes in T-1, and the 13th node in T-2. Fresh and dry weights of leaf except petiole, regardless of harvesting time, increased as the node position was higher, The higher the fruiting position was, the lower the leaf weight was. Therefore, it is recommended to irrigate more frequently during the mid-noon. Fruits can be harvested earlier at the lower nodes in the spring crop production.

• Korea journal of population studies
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• v.20 no.1
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• pp.65-96
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• 1997

The main purpose of this study is to explore the determinants of sex ratio imbalance at birth in Taegu which has experienced the extremely imbalanced sex ratio at birth since mid-1980s. This paper attempts to compare the determinants of sex ratio imbalance at birth, such as sex discrimination against women, son preference, prenatal sex identification followes by sex-selective induced abortions, among married women aged 25 to 44 in Taegu with those in Bay area, California in USA. The research is based on the survey data which were conducted in Taegu, Repulic of Korea and Bay area, California in USA. The findings of this analysis suggest that married women in Taegu are more likely to feel sex discrimination against women than married women in Bay area. Furthermore, the percentage of married women's effort for son bearing before pregnancy is much higher than that of married women in Bay area. We also have found that the percentage of sex-selective induced abortion in Taegu is six times higher than that of married women in Bay area. According to the logistic regression analysis, the determinants of sex-selective induced abortion among married women in Taegu are discrimination against women, son preference, prenatal sex identification. On the other hand, age is the only variable which has an important impact on sex-selective induced abortion among married women in Bay area. From the findings of this study, we can conclude that son preference based on Cofucianism is the most important impact on sex ratio imbalance at birth in Taegu where son preference is much stronger than other regions in Korea. The phenomenon of extremely imbalanced sex ratio at birth in Taegu is the result of combination of these factors, such as strong son preference, seeking to have at least one son within small family size, and prenatal sex identification followed by sex-selective induced abortion.

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.13-43
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• 2017

In the Hapcheon area, hypersthene-bearing monzonite (mangerite) and syenite are recognized. The main minerals of syenite are alkali feldspar, plagioclase, amphibole, biotite, and quartz. Anhedral hornblende and biotite are interstitial between feldspar and quartz, indicating that the hydrous minerals were crystallized later on. Based on petrochemical studies of major elements, syenite is alkaline series, metaluminous, and I-type. The variation patterns in the trace and rare earth elements of mangerite and syenite show the features of subduction-related igneous rock such as depletion of HFSE, relative enrichment in LILE to LREE, and negative Nb-P-Ti anomalies. Based on the experimental data and petrographic characteristics of the syenite, Hapcheon syenitic magma is considered to be formed by partial melting in a dry system. SHRIMP U-Pb zircon data yield the Triassic age as $227.4{\pm}1.4Ma$ in mangerite, $215.3{\pm}1.2Ma$ in syenite, and $217.9{\pm}2.6Ma$ in coarse-grained syenite, respectively. The mangerite age is similar to those of post-collisional plutonic rocks in Hongseong (226~233 Ma), Yangpyeong (227~231 Ma), and Odaesan (231~234 Ma) areas in the Gyeonggi Massif. Syenites were intruded after about 10 Ma. The features seen in the mangereite and syenite rocks can be explained by models such as the continental collision and slab break-off and the lithosphere thinning and asthenosphere upwelling model.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.520-526
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• 2015

Reinforcing bar splices are inevitable in reinforced concrete structure. In these days, there are three main types of splices used in reinforced concrete construction site - lapped splice, mechanical splice and welded splice. Low cost, practicality in construction site, less time consuming and high performance make gas pressure welding become a favorable splice method. However, reinforcing bar splice experiences thermal loading history during the welding procedure. This may lead to the presence of residual stress in the vicinity of the splice which affects the fatigue life of the reinforcing bar. Therefore, residual stress analysis and tensile test of the gas pressure welded splice are carried out in order to verify the load bearing capacity of the gas pressure welded splice. The reinforcing bar used in this work is SD400, which is manufactured in accordance with KS D 3504. The results show that the residual stresses in welded splice is relatively small, thus not affecting the performance of the reinforcing bar. Moreover, the strength of the gas pressure welded splice is high enough for the development of yielding in the bar. As such, the reinforcing bar with gas pressure welded splice has enough capacity to behave as continuous bar.

• Journal of Conservation Science
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• v.27 no.1
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• pp.31-40
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• 2011

Copper-red (Dongwha, Jinsa) is Korean traditional inorganic pigment used for red-coloring on the porcelain surface during Goryeo and Joseon Periods. Trace amounts of copper-red porcelains are handed down because of the technical difficulty of making and coloring of the pigment. It is known that copper ore sources were extensively distributed in Korea according to old literatures and some of them are still producing copper ore at this present. Main types of copper-bearing mineral in Korea are chalcopyrite ($CuFeS_2$) and malachite ($Cu_2CO_3(OH)_2$), and they are easily collected from the ground surface. This means Korea had geographical and economic geological advantages for supplying raw material of the pigment. These two minerals showed good red-coloring in color test for porcelain pigment. As a coloring element, copper showed micro size less than $5{\mu}m$ in diameter in glaze matrix. The dispersion of copper particle is the most decisive factor for red chromaticity of copper-red porcelain, as well as copper content of the pigment.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.133-144
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• 2009

Incheon Bridge, 18.4 km long sea-crossing bridge, will be opened to the traffic in October 2009 and this will be the new landmark of the gearing up north-east Asia as well as the largest & longest bridge of Korea. Incheon Bridge is the integrated set of several special featured bridges including a magnificent cable-stayed girder bridge which has a main span of 800 m width to cross the navigation channel in and out of the Port of Incheon. Incheon Bridge is making an epoch of long-span bridge designs thanks to the fully application of the AASHTO LRFD (load & resistance factor design) to both the superstructures and the substructures. A state-of-the-art of the geotechnologies which were applied to the Incheon Bridge construction project is introduced. The most Large-diameter drilled shafts were penetrated into the bedrock to support the colossal superstructures. The bearing capacity and deformational characteristics of the foundations were verified through the world's largest static pile load test. 8 full-scale pilot piles were tested in both offshore site and onshore area prior to the commencement of constructions. Compressible load beyond 30,000 tonf pressed a single 3 m diameter foundation pile by means of bi-directional loading method including the Osterberg cell techniques. Detailed site investigation to characterize the subsurface properties had been carried out. Geotextile tubes, tied sheet pile walls, and trestles were utilized to overcome the very large tidal difference between ebb and flow at the foreshore site. 44 circular-cell type dolphins surround the piers near the navigation channel to protect the bridge against the collision with aberrant vessels. Each dolphin structure consists of the flat sheet piled wall and infilled aggregates to absorb the collision impact. Geo-centrifugal tests were performed to evaluate the behavior of the dolphin in the seabed and to verify the numerical model for the design. Rip-rap embankments on the seabed are expected to prevent the scouring of the foundation. Prefabricated vertical drains, sand compaction piles, deep cement mixings, horizontal natural-fiber drains, and other subsidiary methods were used to improve the soft ground for the site of abutments, toll plazas, and access roads. Light-weight backfill using EPS blocks helps to reduce the earth pressure behind the abutment on the soft ground. Some kinds of reinforced earth like as MSE using geosynthetics were utilized for the ring wall of the abutment. Soil steel bridges made of corrugated steel plates and engineered backfills were constructed for the open-cut tunnel and the culvert. Diverse experiences of advanced designs and constructions from the Incheon Bridge project have been propagated by relevant engineers and it is strongly expected that significant achievements in geotechnical engineering through this project will contribute to the national development of the longspan bridge technologies remarkably.

• Journal of the Korean Geosynthetics Society
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• v.16 no.2
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• pp.35-45
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• 2017

Gravel compaction pile (GCP) is widely used as it increases the bearing capacity of soft ground and reduces the consolidation settlement. Stress concentration ratio for design is dependent on the area replacement, surcharge pressure, depth and penetration rate. However, a range of stress concentration ratio obtained through field, laboratory experiments and numerical analysis is large. But since the main objective of the study is to evaluate the stress concentration ratio and settlement for both area replacement ratio and penetration rate through numerical analysis. Numerical analysis using the finite element program ABAQUS 6.12-4 has been performed for the composite ground with GCP. As a result, the stress concentration ratio at the points except for the point of top is in the range of 1.21-5.36, 1.19-5.45, 2.16-5.60 for 60%, 80% and 100% penetration, respectively. In general, as the penetration rate and area replacement ratio increases, the stress concentration ratio tends to increase.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.37-50
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• 2016

Gravel compaction pile (GCP) is widely used as it increases the bearing capacity of soft ground and reduces the consolidation settlement. Stress concentration ratio for GCP design is dependent on the area replacement, surcharge pressure and depth. However, a range of stress concentration ratio obtained through field, laboratory experiments and numerical analysis is large. Little study has been done on the stress concentration ratio for the mixing ratio of gravel and sand. The main objective of the study is to evaluate the stress concentration ratio for both area replacement ratio and mixing ratio through literature review and numerical analysis. Numerical analysis using the finite element program ABAQUS 6.12-4 has been performed for the composite ground with GCP. The excess pore water pressure and stress concentration ratio of composite ground have been analyzed for both the area replacement ratio and the mixing ratio. Based on the previous research results, a range of stress concentration ratio obtained from the field tests, laboratory tests, numerical analysis on the GCP studies is found to be 1.7-3.2, 2.0-7.5 and 2.0-6.5, respectively. Based on the numerical analysis results, as the area replacement ratio increases, the stress concentration ratio increases up to 30% and then decreases at 40%. Also, the stress concentration ratio tends to increase up to 70:30 and then to decrease after 60:40.