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Skarn Evolution and Fe-(Cu) Mineralization at the Pocheon Deposit, Korea (한국 포천 광상의 스카른 진화과정 및 철(-동)광화작용)

  • Go, Ji-Su;Choi, Seon-Gyu;Kim, Chang Seong;Kim, Jong Wook;Seo, Jieun
    • Economic and Environmental Geology
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    • v.47 no.4
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    • pp.335-349
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    • 2014
  • The Pocheon skarn deposit, located at the northwestern part of the Precambrian Gyeonggi massif in South Korea, occurs at the contact between the Cretaceous Myeongseongsan granite and the Precambrian carbonate rocks, and is also controlled by N-S-trending shear zone. The skarn distribution and mineralogy reflects both structural and lithological controls. Three types of skarn formations based on mineral assemblages in the Pocheon skarn exist; a sodiccalcic skarn and a magnesian skarn mainly developed in the dolostone, and a calcic skarn developed in the limestone. Iron mineralization occurs in the sodic-calcic and magnesian skarn zone, locally superimposed by copper mineralization during retrograde skarn stage. The sodic-calcic skarn is composed of acmite, diopside, albite, garnet, magnetite, maghemite, anhydrite, apatite, and sphene. Retrograde alteration consists of tremolite, phlogopite, epidote, sericite, gypum, chlorite, quartz, calcite, and sulfides. Magnesian skarn mainly consists of diopside and forsterite. Pyroxene and olivine are mainly altered to tremolite, with minor phlogopite, talc, and serpentine. The calcic skarn during prograde stage mainly consists of garnet, pyroxene and wollastonite. Retrograde alteration consists of epidote, vesuvianite, amphibole, biotite, magnetite, chlorite, quartz, calcite, and sulfides. Microprobe analyses indicate that the majority of the Pocheon skarn minerals are enriched by Na-Mg composition and have high Fe3+/Fe2+, Mg2+/Fe2+, and Al3+/Fe2+ ratios. Clinopyroxene is acmitic and diopsidic composition, whereas garnet is relatively grossular-rich. Amphiboles are largely of tremolite, pargasite, and magnesian hastingsite composition. The prograde anhydrous skarn assemblages formed at about 400500C in a highly oxidized environment (fO2=10231026) under a condition of about 0.5 kbar pressure and X(CO2)=0.10. With increasing fluid/rock interaction during retrograde skarn, epidote, amphibole, sulfides and calcite formed as temperature decreased to approximately 250400C at X(CO2)=0.10.

Effect of Storage Temperature and Humidity on Water Vapor Permeability of Al-foil Laminate Paper (저장온도(貯藏溫度) 및 습도(濕度)가 알루미늄박(箔) 적층지(積層紙)의 수분투과율(水分透過率)에 미치는 영향(影響))

  • Park, Kil-Dong;Choi, Jin-Ho;Sung, Hyun-Soon;Hong, Soon-Keun
    • Korean Journal of Food Science and Technology
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    • v.13 no.4
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    • pp.314-318
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    • 1981
  • In order to improve the storage stability of spray and freeze dried red ginseng extract powder packed in a bottle, the water vapor permeability of Al-foil laminate paper used for cap closure and shelf life of those products on various storage temperatures and relative humidities were investigated. The thickness of the laminate paper was 93±3μm and its physical properties were equal to standard of ASTM (B-377-66) The absorption rate of the freeze dried powder was 2-6 times greater than that of the spray dried powder at 37C. Therefore it was considered that the laminate could be used for cap closures for the spray dried powder but unsuitable for the freeze dried powder. The shelf life of the spray dried powder was longer than that of the freeze-dried powder at 37C.

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Classification of Weathering for the Granite and Granite Gneiss in Okcheon Belt-JecheonGeumsanGimcheon in Korea (옥천대지역 -제천금산김천 - 에 분포하는 화강암 및 화강 편마암의 풍화분류에 관한 고찰)

  • Woo, Ik;Park, Hyuk-Jin
    • Economic and Environmental Geology
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    • v.37 no.3
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    • pp.355-364
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    • 2004
  • A study on the weathering grade classification has been performed for granite and granite gneiss in Korea. The qualitative classification criteria of weathering were reviewed and then modified with field studies for the weathered rock masses. The thin section observations and XRD analyses for the different weathering grades rock samples showed the petrographical and petrophysical difference with respect to the weathering : the proportion of weathering-resistant minerals suck at quartz and orthoclase has a tendency to increase with the development of weathering, but that of weathering-sensible minerals such as anorthite and biotite is decreased. The ranges of physical and mechanical rock properties for different weathering grades were obtained from the laboratory rock tests and field tests for the studied rocks. And then, along with RDIsq(Fookes et al., 1988), the weathering index Ia, (Woo, 2003) has been developed in this study to demarcate the weathering grade. Those two indices rely mainly on the water absorption ratio of rock and on the different rock strength. The range of these weathering indices have been determined with the physical and mechanical rock properties that can be obtained from simple field or laboratory tests in 4 grades Ia> 7 for F, 3.5 < Ia < 10 for SW, 1.0 Ia< 6.0 for MW and Ia< 2.5 for HW. Consequently, the weathering index could be utilized to classify quantitatively the rock weathering grade, especially for the studied granites and the granite gneiss in Korea.

Fabrication and Characterization of High Luminance WOLED Using Single Host and Three Color Dopants (단일 호스트와 3색 도펀트를 이용한 고휘도 백색 유기발광다이오드 제작과 특성 평가)

  • Kim, Min Young;Lee, Jun Ho;Jang, Ji Geun
    • Korean Journal of Materials Research
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    • v.26 no.3
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    • pp.117-122
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    • 2016
  • White organic light-emitting diodes with a structure of indium-tin-oxide [ITO]/N,N-diphenyl-N,N-bis-[4-(phenylm-tolvlamino)-phenyl]-biphenyl-4,4-diamine [DNTPD]/[2,3-f:2, 2-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile [HATCN]/1,1-bis(di-4-poly-aminophenyl) cyclo -hexane [TAPC]/emission layers doped with three color dopants/4,7-diphenyl-1,10-phenanthroline [Bphen]/Cs2CO3/Al were fabricated and evaluated. In the emission layer [EML], N,N-dicarbazolyl-3,5-benzene [mCP] was used as a single host and bis(2-phenyl quinolinato)-acetylacetonate iridium(III) [Ir(pq)2acac]/fac-tris(2-phenylpyridinato) iridium(III) [Ir(ppy)3]/iridium(III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate [FIrpic] were used as red/green/blue dopants, respectively. The fabricated devices were divided into five types (D1, D2, D3, D4, D5) according to the structure of the emission layer. The electroluminescence spectra showed three peak emissions at the wavelengths of blue (472~473 nm), green (495~500 nm), and red (589~595 nm). Among the fabricated devices, the device of D1 doped in a mixed fashion with a single emission layer showed the highest values of luminance and quantum efficiency at the given voltage. However, the emission color of D1 was not pure white but orange, with Commission Internationale de L'Eclairage [CIE] coordinates of (x = 0.41~0.45, y = 0.41) depending on the applied voltages. On the other hand, device D5, with a double emission layer of mCP:[Ir(pq)2acac(3/mCP:[FIrpic(10%)], showed a nearly pure white color with CIE coordinates of (x = 0.34~0.35, y = 0.35~0.37) under applied voltage in the range of 6~10 V. The luminance and quantum efficiency of D5 were 17,160cd/m2 and 3.8% at 10 V, respectively.

In Situ-DRIFTS Study of Rh Promoted CuCo/Al2O3 for Ethanol Synthesis via CO Hydrogenation

  • Li, Fang;Ma, Hongfang;Zhang, Haitao;Ying, Weiyong;Fang, Dingye
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2726-2732
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    • 2014
  • The promoting effect of rhodium on the structure and activity of the supported Cu-Co based catalysts for CO hydrogenation was investigated in detail. The samples were characterized by DRIFTS, N2-adsorption, XRD, H2-TPR, H2-TPD and XPS. The results indicated that the introduction of rhodium to Cu-Co catalysts resulted in modification of metal dispersion, reducibility and crystal structure. DRIFTS results of CO hydrogenation at reaction condition (P=2 MPa, T=260C) indicated the addition of 1 wt % rhodium improved hydrogenation ability of Cu-Co catalysts. The ethanol selectivity and CO conversion were both improved by 1 wt % Rh promoted Cu-Co based catalysts. The alcohol distribution over un-promoted and rhodium promoted Cu-Co based catalysts obeys A-S-F rule and higher chain growth probability was got on rhodium promoted catalyst.

UY Ursae Majoris: An A-Subtype W UMa System with a Very Large Fill-Out Factor and an Extreme Mass Ratio

  • Kim, Chun-Hwey;Song, Mi-Hwa;Park, Jang-Ho;Jeong, Min-Ji;Kim, Hye-Young;Han, Cheongho
    • Journal of Astronomy and Space Sciences
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    • v.36 no.4
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    • pp.265-281
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    • 2019
  • We present new BVRI light curves of UY UMa with no O'Connell effect and a flat bottom secondary eclipse. Light curve synthesis with the Wilson-Devinney code gives a new solution, which is quite different from the previous study: UY UMa is an A-subtype over-contact binary with a small mass ratio of q = 0.21, a high inclination of 81°.4, a small temperature difference of ΔT=18°, a large fill-out factor of f = 0.61, and a third light of approximately 10% of the total systemic light. The absolute dimensions were newly determined. Seventeen new times of minimum light have been calculated from our observations. The period study indicates that the orbital period has intricately varied in a secular period increase in which two cyclical terms with periods of 12y.0 and 46y.3 are superposed. The secular period increase was interpreted to be due to a conservative mass transfer of 2.68 × 10-8 M/yr from the less massive to the more massive star. The cyclical components are discussed in terms of double-light time contributions from two additional bound stars. The statistical relations of Yang & Qian (2015) among the physical parameters of 45 deep, low mass ratio contact binaries were revisited by using the physical parameters of UY UMa and 25 Kepler contact binaries provided by Şenavci et al. (2016).

Fabric Dyeing with Myrobalan(Terminalia chebula Retz.) (미로발란을 이용한 직물염색)

  • Han, Mi-Ran;Lee, Jeong-Sook
    • The Korean Fashion and Textile Research Journal
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    • v.11 no.6
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    • pp.953-960
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    • 2009
  • The natural dyeing of fabrics with myrobalan extract was investigated. After dyeing of silk, cotton and rayon with myrobalan extract, the dyeability of myrobalan extract was evaluated with the conditions of concentration, temperature, time, repeat-numbers, pH, mordants variables, the changes of dyeability and surface colors by methods of mordanting and color fastness. The wavelength of maximum absorption of the colored solution from myrobalan extract appeared at 272 nm. Therefore, the substance of myrobalan extract was verified as tannin dyes. The optimum dyeing of fabrics was carried out at 30%(o.w.f) dye concentration. Silk fabrics dyed with myrobalan extract showed the highest K/S value at the temperature of 80C when it was dyed for seventy minutes, while cotton and rayon fabrics showed the highest K/S value at the temperature of 90C when they were dyed for seventy minutes and thirty minutes, respectively. Dyeing operation was carried out in acidic dyebath of pH 3. The K/S value of silk fabric was higher in pre-mordant stage than in post-mordant, while the K/S values of cotton and rayon fabrics were higher in post-mordant stage. The surface colors of dyed fabrics were different according to used mordants: Al and Cu mordanted fabrics were dyed in yellowish colors, while Fe mordanted fabric was dyed in khaki-black color. Light-fastness of the color fastness was improved in Fe-mordant. Washing-fastness was relatively good, and dry cleaning-fastness of dyed fabrics was excellent.

A Method of Contact Pressure Analysis between Half-space and Plate (탄성지반과 판의 접촉압력해석에 관한 연구)

  • Cho, Hyun Yung;Cheung, Jin Hwan;Kim, Seong Do;Han, Choong Mok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.12 no.1
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    • pp.1-8
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    • 1992
  • A method analizing contact pressure between plate and elastic half space is presented by using F.E.M. With the method, the pressure intensities at surface nodes of half space cae be directly calculated by using flexibility matrix of half space. The method is originally presented by Y.K. Cheung et al.(3) Insted of Y.K. Cheung's method, which use a conception of equi-contact pressure area around each surface nodes of half space in the noded rectanqular element area. We use the equi-contact pressure area around the Gaussian integration points of half space surface in the noded isoparametric element area. Numarical examples are presented and compared with other's studies.

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Improvement of Outcoupled Light Efficiency of Organic Light-emitting Diodes with a Use of Microlens Array (마이크로 렌즈 어레이를 이용한 유기 발광 소자의 광추출 효율 향상에 관한 연구)

  • Kim, Hye Sook;Hwang, Deok Hyeon;Hong, Jin Woong;Song, Min Jong;Han, Wone Keun;Kim, Tae Wan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.5
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    • pp.307-311
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    • 2014
  • Because of a waveguiding effect and total internal reflection caused by a difference in refractive indices, only 20% of generated light is emitted to the air and the rest is trapped or absorbed in the device. An improvement of outcoupled efficiency of organic light-emitting diodes was studied using a microlens array. Mold of microlens array was fabricated by using photo-lithography with the AZ9260 photoresist, and the microlens array was formed onto the glass substrate using the UV curing agent named ZPU13-440. Device structure consists of microlens/glass/ITO/TPD/Alq3/LiF/Al. It was found that there is an improvement of external quantum efficiency by about 20% at the same current density for the device with the microlens array compared to that of the reference one. Simulated outcoupled efficiency shows the improvement by about 20% for the device with the microlens array compared to that of the reference one. These results are consistent with the experimental ones.

Co-Deposition법을 이용한 Yb Silicide/Si Contact 및 특성 향상에 관한 연구

  • Gang, Jun-Gu;Na, Se-Gwon;Choe, Ju-Yun;Lee, Seok-Hui;Kim, Hyeong-Seop;Lee, Hu-Jeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.438-439
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    • 2013
  • Microelectronic devices의 접촉저항의 향상을 위해 Metal silicides의 형성 mechanism과 전기적 특성에 대한 연구가 많이 이루어지고 있다. 지난 수십년에 걸쳐, Ti silicide, Co silicide, Ni silicide 등에 대한 개발이 이루어져 왔으나, 계속적인 저저항 접촉 소재에 대한 요구에 의해 최근에는 Rare earth silicide에 관한 연구가 시작되고 있다. Rare-earth silicide는 저온에서 silicides를 형성하고, n-type Si과 낮은 schottky barrier contact (~0.3 eV)를 이룬다. 또한, 비교적 낮은 resistivity와 hexagonal AlB2 crystal structure에 의해 Si과 좋은 lattice match를 가져 Si wafer에서 high quality silicide thin film을 성장시킬 수 있다. Rare earth silicides 중에서 ytterbium silicide는 가장 낮은 electric work function을 갖고 있어 낮은 schottky barrier 응용에서 쓰이고 있다. 이로 인해, n-channel schottky barrier MOSFETs의 source/drain으로써 주목받고 있다. 특히 ytterbium과 molybdenum co-deposition을 하여 증착할 경우 thin film 형성에 있어 안정적인 morphology를 나타낸다. 또한, ytterbium silicide와 마찬가지로 낮은 면저항과 electric work function을 갖는다. 그러나 ytterbium silicide에 molybdenum을 화합물로써 높은 농도로 포함할 경우 높은 schottky barrier를 형성하고 epitaxial growth를 방해하여 silicide film의 quality 저하를 야기할 수 있다. 본 연구에서는 ytterbium과 molybdenum의 co-deposition에 따른 silicide 형성과 전기적 특성 변화에 대한 자세한 분석을 TEM, 4-probe point 등의 다양한 분석 도구를 이용하여 진행하였다. Ytterbium과 molybdenum을 co-deposition하기 위하여 기판으로 10Ωcm의 비저항을 갖는 low doped n-type Si (100) bulk wafer를 사용하였다. Native oxide layer를 제거하기 위해 1%의 hydrofluoric (HF) acid solution에 wafer를 세정하였다. 그리고 고진공에서 RF sputtering 법을 이용하여 Ytterbium과 molybdenum을 동시에 증착하였다. RE metal의 경우 oxygen과 높은 반응성을 가지므로 oxidation을 막기 위해 그 위에 capping layer로 100 nm 두께의 TiN을 증착하였다. 증착 후, 진공 분위기에서 rapid thermal anneal(RTA)을 이용하여 300700C에서 각각 1분간 열처리하여 ytterbium silicides를 형성하였다. 전기적 특성 평가를 위한 sheet resistance 측정은 4-point probe를 사용하였고, Mo doped ytterbium silicide와 Si interface의 atomic scale의 미세 구조를 통한 Mo doped ytterbium silicide의 형성 mechanism 분석을 위하여 trasmission electron microscopy (JEM-2100F)를 이용하였다.

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