• Title/Summary/Keyword: Filling phase

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Surface-modified Nanoparticle Additives for Wear Resistant Water-based Coatings for Galvanized Steel Plates

  • Becker-Willinger, Carsten;Heppe, Gisela;Opsoelder, Michael;Veith, H.C. Michael;Cho, Jae-Dong;Lee, Jae-Ryung
    • Corrosion Science and Technology
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    • v.9 no.4
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    • pp.147-152
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    • 2010
  • Conventional paints for conversion coating applications in steel production derived mainly from water-based polymer dispersions containing several additives actually show good general performance, but suffer from poor scratch and abrasion resistance during use. The reason for this is because the relatively soft organic binder matrix dominates the mechanical surface properties. In order to maintain the high quality and decorative function of coated steel sheets, the mechanical performance of the surface needs to be improved significantly. In fact the wear resistance should be enhanced without affecting the optical appearance of the coatings by using appropriate nanoparticulate additives. In this direction, nanocomposite coating compositions (Nanomer$^{(R)}$) have been derived from water-based polymer dispersions with an increasing amount of surface-modified nanoparticles in aqueous dispersion in order to monitor the effect of degree of filling with rigid nanoparticles. The surface of nanoparticles has been modified for optimum compatibility with the polymer matrix in order to achieve homogeneous nanoparticle dispersion over the matrix. This approach has been extended in such a way that a more expanded hybrid network has been condensed on the nanoparticle surface by a hydrolytic condensation reaction in addition to the quasi-monolayer type small molecular surface modification. It was expected that this additional modification will lead to more intensive cross-linking in coating systems resulting in further improved scratch-resistance compared to simple addition of nanoparticles with quasi-monolayer surface modification. The resulting compositions have been coated on zinc-galvanized steel and cured. The wear resistance and the corrosion protection of the modified coating systems have been tested in dependence on the compositional change, the type of surface modification as well as the mixing conditions with different shear forces. It has been found out that for loading levels up to 50 wt.-% nanoparticles, the mechanical wear resistance remains almost unaffected compared to the unmodified resin. In addition, the corrosion resistance remained unaffected even after $180^{\circ}$ bending test showing that the flexibility of coating was not decreased by nanoparticle addition. Electron microscopy showed that the inorganic nanoparticles do not penetrate into the organic resin droplets during the mixing process but rather formed agglomerates outside the polymer droplet phase resulting in quite moderate cross linking while curing, because of viscosity. The proposed mechanisms of composite formation and cross linking could explain the poor effect regarding improvement of mechanical wear resistance and help to set up new synthesis strategies for improved nanocomposite morphologies, which should provide increased wear resistance.

The Development of Signal Processing Software for Single-and Multi-Voxel MR Spectroscopy (단위용적 및 다용적 기법 자기공명분광 신호처리 분석 소프트웨어의 개발)

  • Paik, Moon-Young;Lee, Hyun-Yong;Shin, Oun-Jae;Eun, Choong-Ki;Mu, Chi-Woong
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.39 no.5
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    • pp.544-555
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    • 2002
  • The aim of this study is to develop the $^1H$-MRS data postprocessing software for both single-voxel and multi-voxel technique, which plays and important role as a diagnostic tool in clinical field. This software is based on graphical user interface(GUI) under windows operating system of personal computer(PC). In case of single-voxel MRS, both of raw data in time-domain and spectrum data in frequency-domain are simultaneously displayed in a screen. Several functions such as DC correction, zero filling, line broadening, Lorentz-Gauss filtering and phase correction, etc. are included to increase the quality of spectrum data. In case of multi-voxel analysis, spectroscopic image reconstructed by 3-D FFT was displayed as a spectral grid and overlapped over previously obtained T1- or T2-weighted image for the spectra to be spatially registered with the image. The analysis of MRS peaks were performed by obtaining the ratio of peak area. In single-voxel method, statistically processed peak-area ratios of MRS data obtained from normal human brain are presented. Using multi-voxel method, MR spectroscopic image and metabolite image acquired from brain tumor are demonstrated.

A STUDY ON THE EVALUATION OF POLYMERIZATION SHRINKAGE OF COMPOSITE AND COMPOMER USING STRAIN GAUGE METHOD (스트레인 게이지법을 이용한 복합레진과 컴포머의 중합수축 평가에 관한 연구)

  • Kim, Yeun-Chul;Kim, Jong-Soo;Kwon, Soon-Won;Kim, Yong-Kee
    • Journal of the korean academy of Pediatric Dentistry
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    • v.29 no.1
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    • pp.19-29
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    • 2002
  • The purpose of this study was to compare the polymerization shrinkage and the compressive strength of composite and compomer cured with two different light sources ; conventional halogen-light curing unit and recently-developed plasma arc curing unit. The 'strain gauge method' was used for determination of polymerization shrinkage and the compressive strength was measured by universal testing machine. The results of the present study can be summarized as follows: 1. Filling materials in polyethylene molds showed the initial expansion in the early phase of polymerization. This was followed by the rapid contraction in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The polymerization shrinkage in tooth samples was generally lower than in the mold samples. 3. The generally lower amount of linear polymerization shrinkage was observed in compomer and plasma arc curing unit group when compared to composite and conventional curing unit. 4. The higher compressive strength values was found in composite groups regardless curing methods. The results of this study strongly support the application of plasma arc system and fluoride-containing compomer in the field of clinical pediatric dentistry claiming its effectiveness in curing the esthetic dental materials and the anticariogenic capacity.

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Fluid Inclusion and Sulfur Stable Isotope of Buckchang Deposit, Korea (북창광상의 유체포유물 및 황안정동위원소 연구)

  • Chung, Jae-Il;Kim, Seon-Young;Na, Choon-Ki;Lee, In-Sung;Ripley, E.M.
    • Economic and Environmental Geology
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    • v.29 no.6
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    • pp.677-687
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    • 1996
  • The Buckchang deposits which is located in the Ockcheon metamorphic zone, are emplaced along $N20-30^{\circ}E$ trending fissure sets. So it is a sort of fissure-filling ore deposits. The results of mineral paragenetic studies suggest two stages of hydrothermal mineralization; stage I: base-metal sulfides stage, stage II: late base-metal sulfides, electrum and silver-bearing sulfosalts stage. The silver-bearing sulfosalts occured as the Buckchang mine are mainly argentite and, minor of canfieldite, tetrahedrite, etc. Au:Ag ratios of the electrums show a highly limited range of nearly 1:1 in atomic %. The temperature, salinity and pressure of the Buckchang deposits estimated from fluid inclusion and sulfur isotope studies are as follows; stage I: $174{\sim}250^{\circ}C$, 0.35~4.01 NaCl eq. wt.%, 0.40~1.00 Kbar, stage II: $138{\sim}222^{\circ}C$, 1.9~8.4 NaCl eq. wt.%, 0.22~0.53 Kbar. The estimated oxygen and sulfur fugacity during stage I mineralization, based on phase relation of associated minerals, range from $10^{-39.7}{\sim}10^{-44.7}$ atm. and $10^{-13.4}{\sim}10^{-18.1}$ atm., respectively. All these evidences suggest that the Buckchang deposits are polymetallic epithermal ore deposits.

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Poloxamer 407 Hydrogels for Intravesical Instillation to Mouse Bladder: Gel-Forming Capacity and Retention Performance

  • Kim, Sang Hyun;Kim, Sung Rae;Yoon, Ho Yub;Chang, In Ho;Whang, Young Mi;Cho, Min Ji;Kim, Myeong Joo;Kim, Soo Yeon;Lee, Sang Jin;Choi, Young Wook
    • The Korean Journal of Urological Oncology
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    • 제15권3호
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    • pp.178-186
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    • 2017
  • Purpose: Poloxamer 407 (P407) thermo-sensitive hydrogel formulations were developed to enhance the retention time in the urinary bladder after intravesical instillation. Materials and Methods: P407 hydrogels (P407Gels) containing 0.2 w/w% fluorescein isothiocyanate dextran (FD, MW 4 kDa) as a fluorescent probe were prepared by the cold method with different concentrations of the polymer (20, 25, and 30 w/w%). The gel-forming capacities were characterized in terms of gelation temperature (G-Temp), gelation time (G-Time), and gel duration (G-Dur). Homogenous dispersion of the probe throughout the hydrogel was observed by using fluorescence microscopy. The in vitro bladder simulation model was established to evaluate the retention and drug release properties. P407Gels in the solution state were administered to nude mice via urinary instillation, and the in vivo retention behavior of P407Gels was visualized by using an in vivo imaging system (IVIS). Results: P407Gels showed a thermo-reversible phase transition at $4^{\circ}C$ (refrigerated; sol) and $37^{\circ}C$ (body temperature; gel). The G-Temp, G-Time, and G-Dur of FD-free P407Gels were approximately $10^{\circ}C-20^{\circ}C$, 12-30 seconds, and 12-35 hours, respectively, and were not altered by the addition of FD. Fluorescence imaging showed that FD was spread homogenously in the gelled P407 solution. In a bladder simulation model, even after repeated periodic filling-emptying cycles, the hydrogel formulation displayed excellent retention with continuous release of the probe over 8 hours. The FD release from P407Gels and the erosion of the gel, both of which followed zero-order kinetics, had a linear relationship ($r^2=0.988$). IVIS demonstrated that the intravesical retention time of P407Gels was over 4 hours, which was longer than that of the FD solution (<1 hour), even though periodic urination occurred in the mice. Conclusions: FD release from P407Gels was erosion-controlled. P407Gels represent a promising system to enhance intravesical retention with extended drug delivery.

History of Disease Control of Korean Ginseng over the Past 50 Years (과거 50년간 고려인삼 병 방제 변천사)

  • Dae-Hui Cho
    • Journal of Ginseng Culture
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    • v.6
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    • pp.51-79
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    • 2024
  • In the 1970s and 1980s, during the nascent phase of ginseng disease research, efforts concentrated on isolating and identifying pathogens. Subsequently, their physiological ecology and pathogenesis characteristics were scrutinized. This led to the establishment of a comprehensive control approach for safeguarding major aerial part diseases like Alternaria blight, anthracnose, and Phytophthora blight, along with underground part diseases such as Rhizoctonia seedling damping-off, Pythium seedling damping-off, and Sclerotinia white rot. In the 1980s, the sunshade was changed from traditional rice straw to polyethylene (PE) net. From 1987 to 1989, focused research aimed at enhancing disease control methods. Notably, the introduction of a four-layer woven P.E. light-shading net minimized rainwater leakage, curbing Alternaria blight occurrence. Since 1990, identification of the bacterial soft stem rot pathogen facilitated the establishment of a flower stem removal method to mitigate outbreaks. Concurrently, efforts were directed towards identifying root rot pathogens causing continuous crop failure, employing soil fumigation and filling methods for sustainable crop land use. In 2000, adapting to rapid climate changes became imperative, prompting modifications and supplements to control methods. New approaches were devised, including a crop protection agent method for Alternaria stem blight triggered by excessive rainfall during sprouting and a control method for gray mold disease. A comprehensive plan to enhance control methods for Rhizoctonia seedling damping-off and Rhizoctonia damping-off was also devised. Over the past 50 years, the initial emphasis was on understanding the causes and control of ginseng diseases, followed by refining established control methods. Drawing on these findings, future ginseng cultivation and disease control methods should be innovatively developed to proactively address evolving factors such as climate fluctuations, diminishing cultivation areas, escalating labor costs, and heightened consumer safety awareness.

Mineralogy and Genetic Environments of the Seongdo Pb-Zn deposit, Goesan (괴산 성도 연-아연 광상의 산출광물과 생성환경)

  • Ahn, Seongyeol;Shin, Dongbok
    • Economic and Environmental Geology
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    • v.50 no.5
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    • pp.325-340
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    • 2017
  • The Seongdo Pb-Zn deposit, located in the northwestern part of the Ogcheon Metamorphic Belt, consists of skarn ore replacing limestone within the Hwajeonri Formation of Ogcheon Group and hydrothermal vein ore filling the fracture of host rock. Skarn minerals comprise mostly hedenbergitic pyroxene, garnet displaying oscillatory zonal texture composed of grossular and andradite, and a small amount of wollastonite, tremolite, and epidote, indicating reducing condition of formation. Ore minerals of skarn ore include sphalerite and galena with a small amount of pyrite, pyrrhotite, and chalcopyrite. In hydrothermal vein ore, arsenopyrite, sphalerite, chalcopyrite, and pyrite occur with a small amount of galena, native Bi, and stannite. Chemical compositions of sphalerite vary from 17.4 mole% FeS in average for dark grey sphalerite, 3.6 mole% for reddish brown sphalerite in skarn ore, and to 10.3 mole% FeS in hydrothermal vein ore. In comparison with representative metallic deposits in South Korea on the FeS-MnS-CdS diagram, skarn and hydrothermal vein ore plot close to the field of Pb-Zn deposits and Au-Ag deposits, respectively. Arsenic contents of arsenopyrite in hydrothermal vein ore decrease from 31.93~33.00 at.% in early stage to 29.58~30.21 at.% in middle stage, and their corresponding mineralizing temperature and sulfur fugacity are $441{\sim}490^{\circ}C$, $10^{-6}{\sim}10^{-4.5}atm$. and $330{\sim}364^{\circ}C$, <$10^{-8}atm$. respectively. Phase equilibrium temperatures calculated from Fe and Zn contents for coexisting sphalerite and stannite in hydrothermal vein are $236{\sim}254^{\circ}C$. Sulfur isotope compositions are 5.4~7.2‰ for skarn ore and 5.4~8.4‰ for hydrothermal vein ore, being similar or slightly higher to magmatic sulfur, suggesting that ore sulfur was mostly of magmatic origin with partial derivation from host rocks. However, much higher sulfur isotope equilibrium temperatures of $549^{\circ}C$$487^{\circ}C$, respectively for skarn ore and hydrothermal ore, than those estimated from phase equilibria imply that isotopic equilibrium has not been fully established.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

A STUDY ON THE POLYMERIZATION SHRINKAGE OF COMPOSITE RESIN ACCORDING TO VARIOUS LIGHT-CURING METHODS (광조사 방법에 따른 복합레진의 중합수축에 관한 연구)

  • Kwon, Oh-Jin;Kim, Jong-Soo;Kwon, Soon-Won
    • Journal of the korean academy of Pediatric Dentistry
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    • v.30 no.1
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    • pp.102-109
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    • 2003
  • The purpose of this study was to evaluate the linear polymerization shrinkage(%) and microhardness of composite resin(Z-100, 3M, USA) according to 2-step light curing method. Conventional light curing unit(Curing Light 2500, 3M USA) and 2-step light curing unit(Elipar Highlight, ESPE, Germany) were used as light source. The strain gauge method was used for determination of polymerization shrinkage(%). Samples were divided by 3 groups according to light curing methods (Group I : $450mW/cm^2$, 40sec, Group II : $650mW/cm^2$, 40sec, Group III : $150mW/cm^2$, 10sec & $650mW/cm^2$, 30sec). Preparations of acrylic molds were followed by filling and curing. Strain gauges attached to each sample were connected to a strainmeter. Measurements were recorded at each second for the total of 10 minutes including the periods of light application. And microhardness of each group after 24hours from light irradiation were measured. Obtained data were analyzed statistically using Ore-way ANOVA and/or Scheffe test. The results of the present study can be summarized as follows: 1. Composite resin in acrylic molds showed the initial expansion at the early phase of polymerization. This was followed by the contraction with the rapid increase in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The lowest linear polymerization shrinkage(%) was found in group III followed by group I, II during the measuring periods. 3. Group III using 2-step curing method showed statistically significant reduction of linear polymerization shrinkage(%) compared with group I, II at 1 minute and 10 minutes from light irradiation(p<0.05). 4. The microhardness values of each group not revealed significant difference.

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Fluid Inclusion Studies on the Wolak Tungsten-Molybdenum Deposits, Korea (월악 중석-몰리브덴 광상의 유체포유물 연구)

  • Lee, In Sung;Park, Hee-In
    • 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.

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