• Economic and Environmental Geology
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• v.21 no.2
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• pp.149-164
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• 1988

Electrum-sulfide mineralization of the Samgwang and Sobo mines of the Cheongyang Au-Ag area was deposited in two stages of quartz and calcite veins that fill fault zones in granite gneiss. Radiometric dating indicates that mineralization is Early Cretaceous age (127 Ma). Fluid inclusion and sulfur isotope data show that ore mineralization was deposited at temperatures between $340^{\circ}$ and $180^{\circ}C$ from fluids with salinities of 1 to 8 wt. % equiv. NaCl and a ${\delta}^{34}S_{{\sum}S}$ value of 2 to 5 per mil. Evidence of fluid boiling (and $CO_2$ effervescence) indicates a range of pressures from < 200 to $\approx$ 700 bars, corresponding to depths of ${\approx}1.5{\pm}0.3\;km$ in a hydrothermal system which alternated from lithostatic toward hydrostatic conditions. Au-Ag deposition was likely a result of boiling coupled with cooling. Meaured and calculated hydrogen and oxygen isotope values of ore-forming fluids indicate a significant meteoric water component, approaching unexchanged paleometeoric water values. Comparison of these values with those of other Korean Au-Ag deposits reveals a relationship among depth, Au/Ag ratio and degree of water-rock interaction. All investigated Korean Jurassic and Cretaceous gold-silver-bearing deposits have fluids which are dominantly evolved meteoric waters, but only deeper systems (${\geq}1.5\;km$) are exclusively gold-rich.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.27-36
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• 2006

We fabricated thermally evaporated 10 nm-Ni/(poly)Si, 10 nm-Ni/l nm-Ir/(poly)Si and 10 nm-Ni/l nm-Pt/(poly)Si films to investigate the thermal stability of nickel monosilicides at the elevated temperatures by rapid annealing them at the temperatures of $300{\sim}1200^{\circ}C$ for 40 seconds. Silicides of 50 nm-thick were formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to examine sheet resistance. A scanning electron microscope and field ion beam were employed for thickness and microstructure evolution characterization. An X-ray diffractometer and an Auger depth profiler were used for phase and composition analysis, respectively. Nickel silicides with platinum have no effect on widening the NiSi stabilization temperature region. Nickel silicides with iridium farmed on single crystal silicon showed a low resistance up to $1200^{\circ}C$ while the ones formed on polycrystalline silicon substrate showed low resistance up to $850^{\circ}C$. The grain boundary diffusion and agglomeration of silicides lowered the NiSi stable temperature with polycrystalline silicon substrates. Our result implies that our newly proposed Ir added NiSi process may widen the thermal process window for nano CMOS process.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.282-291
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• 2012

The PGLE and PGLE3 nonionic surfactants were synthesized from the reaction between glycidol and lauryl acid and their structures were confirmed by $^1H$ and $^{13}C$ NMR analysis. The CMCs of PGLE and PGLE3 surfactants were found to be $3.59{\times}10^{-2}$ mol/L and $8.80{\times}10^{-2}$ mol/L respectively and the surface tensions at their CMC conditions were 26.09 mN/m and 28.68 mN/m respectively. Dynamic surface tension measurement has shown that the adsorption rate of surfactant molecules at the interface between air and surfactant solution was found to be relatively fast in both surfactant systems, presumably due to high mobility of surfactant molecules. The contact angles of PGLE and PGLE3 nonionic surfactants were $25.5^{\circ}$ and $9.5^{\circ}$ respectively. Dynamic interfacial tension measurement showed that both surfactant systems reached equilibrium in 20 minutes and the interfacial tensions at equilibrium condition in both systems were 0.42 mN/m and 0.53 mN/m respectively. The PGLE surfactant system has indicated higher foam stability than the PGLE3 surfactant system, which is consistent with surface tension measurement. The phase behavior experiments performed at $25{\sim}60^{\circ}C$ in systems containing nonionic surfactant, water, n-hydrocarbon oil and cosurfactant showed a lower phase or oil in water microemulsion in equilibrium with excess oil phase at all conditions investigated during this study.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.77-78
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• 2006

최근 flexible OLED의 구동에 사용하기 위한 유기박막트랜지스터(Organic Thin Film Transistor, OTFT)의 연구에서는 용매에 용해되어 spin coating이 가능한 재료의 개발에 관심을 두고 있다. 현재 pentacene으로는 아직 spin coating으로 제작할 수 있는 상용화된 제품이 없고 spin coating이 가능한 활성층 물질(active material)로 P3HT가 쓰이고 있다. 본 연구에서는 용해 가능한 P3HT 활성층 물질과 여러 종류의 용해 가능한 게이트 절연물(gate insulator, Gl)을 사용하여 안정된 소자를 구현할 수 있는 공정을 개발하는 목적으로 metal-insulator-semironductor(MIS) 소자를 제작하여 C-V 특성을 측정하고 분석하였다. 먼저 7mm${\times}$7mm 크기의 pyrex glass 시편 위에 바닥 전극으로 $1600{\AA}$ Au을 증착하고 spin coating 방식을 이용하여 PVP, PVA, PVK, BCB, Pl의 5종류의 게이트 절연층을 각각 형성하였고 그 위에 같은 방법으로 P3HT를 코팅하였다. P3HT 코팅 시 bake 공정의 유무와 spin rpm의 변화에 따른 P3HT의 두께를 측정하였다. Gl의 종류별로 주파수에 따른 capatltancc를 측정하여 비교, 분석하였다. C-V 측정 결과 PVP, PVA, PVK, BCB, Pl의 단위 면적당 capacitance 값은 각각 1.06, 2.73, 2.94, 3.43, $2.78nF/cm^2$로 측정되었다. Threshold voltage, $V_{th}$는 각각 -0.4, -0.7, -1.6, -0.1, -0.2V를 나타냈다. 주파수에 따른 capacitance 변화율을 측정한 결과 Gl 물질 모두 주파수가 높을수록 capacitance가 점점 감소하는 경향을 보였으나 1${\sim}$2nF 이내의 범위에서 작은 변화율만 나타냈다. P3HT의 두께와 bake 온도를 변화시켜 C-V 값을 측정한 결과 차이는 없었다. FE-SEM으로 관찰한 결과에서도 두께나 온도에 따른 P3HT의 표면 morphology 차이를 확인할 수 없었다. 본 연구에서 PVK와 P3HT의 조합이 수율(yield)면에서 가장 안정적이면서 $3.43\;nF/cm^2$의 가장 높은 capacitance 값을 나타내고 $V_{th}$ 값 또한 -1.6V로 가장 낮은 값을 보였다.

• Journal of the Korean earth science society
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• v.29 no.3
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• pp.263-279
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• 2008

This study is concerned with the optimization of models using MM5 and WRF mesoscale numerical models to simulate strong sea surface winds, such as that of typhoon Shanshan on 17 September 2006, and the Siberian high event on 16 December 2006, which were selected for displaying the two highest mean wind speeds. The model optimizations for the lowest level altitude, physical parameters and horizontal resolution were all examined. The sea surface wind values obtained using a logarithmic function which takes into account low-level stability and surface roughness were more accurate than those obtained by adjusting the lowest-level of the model to 10 m linearly. To find the optimal parameters for simulating strong sea surface winds various physical parameters were combined and applied to the model. Model grid resolutions of 3-km produced better results than those of 9-km in terms of displaying accurately regions of strong wind, low pressure intensities and low pressure mesoscale structures.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.279-291
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• 2020

It has already been a few years since the word Fintech in Korea started to attract attention. These days, they believed that Fintech was just a boom, but these days it is recognized as a catalyst for financial transformation. Large venture companies are also launching demonstration experiments by creating new organizations that can respond to Fintech. It feels like a big tide is coming to the cautious and conservative financial industry. Finance is made up of digital information. Fintech is an evolutionary process in which finance, expressed by digital information, is transformed into information technology (IT) and human economic activities are reorganized. It is FinTech. You won't be able to understand the real effects of Fintech by sticking to individual applications like remittance payments or household account book services. Fintech is an innovation that changes the structure of economic activity itself. In fact, it is from now on that a big impact will come. In other words, now is the time when we are thinking of a dream that we have not yet dreamed of. In this paper, I will examine how fintech originated, spread to Korea, and how it intends to change Korea's finance in the future. Financial institutions have used the fruits of information technology advances in the direction of pursuing stability and stability, without major changes in the way they work. However, the movement of Fintech that started in Silicon Valley in the United States shows that the fruit can be used in other directions. The fruit of technological progress is expected to expand year by year in the future. It is a request of the times to use it to improve user convenience and to pursue innovation that is beneficial to society. We expect the flow of Fintech to accelerate innovation in the Korean financial industry.

• Journal of the Korean Chemical Society
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• v.66 no.3
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• pp.185-193
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• 2022

The theoretical investigation has been performed to predict thermodynamic stability, density, detonation velocity, and detonation pressure of energetic salts produced by pairing of nitrogen-rich anions (tetrazine, oxadiazole etc.) and cations (NH₃OH⁺, NH₂NH₃⁺, CH₉N₆⁺, C₂H₆N₅⁺). All possible geometries and the binding energy for the trigger bond of energetic salts have been optimized at the B3LYP/cc-pVDZ level of theory. The detonation velocity and detonation pressure have been calculated using Kamlet-Jacobs equation, while enthalpy has been predicted at the G2MP2 level of theory. The predicted results reveal that the energetic salts including small sized NH₃OH⁺(1) and NH₂NH₃⁺(2) cations increase detonation property. And also the energetic salts including more amino group (-NH₂) such as CH₉N₆⁺(3) cation increase thermodynamic stability. These results provide basic information for the development the high energy density materials (HEDMs).

• Journal of Life Science
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• v.32 no.12
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• pp.956-961
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• 2022

Plant Chloroplast have several advantages as an expression platform of biopharmaceuticals over conventional expression platforms such as mammalian cells, yeast and bacteria. First, plants do not serve as a host for mammalian infectious virus and have endotoxin like bacteria which can cause anaphylactic shock. In addition, high copy number of chloroplast genome allows for chloroplast transformants to reach the high level of expression of heterologous genes. Moreover, the integration of transgenes into specific region of chloroplast genomes makes chloroplast transformants unaffected by positional effect which can be frequently observed from nuclear transformants, resulting in loss of transgene expressions. Antimicrobial peptides (AMPs) are a kind of innate immunity which is found from bacteria to humans. Unlike conventional antibiotics, very less dosage of AMPs can have catastrophic effect on bacterial survival. Further, the repeated use of AMPs does not trigger the development of bacterial resistance. Moricin, one of the AMPs, was isolated from Bombyx mori, a silkworm moth. The C-terminal of moricin consists largely of basic amino acids, and the N-terminal has an α-helix structure. Moricin was chosen and expressed in a SUMO/SUMOase without leaving any unwanted amino acids which could potentially affect the anti-bacterial activity of the moricin. The transformation vector used in this study has already been created in this lab for the expression in both prokaryotic systems such as E. coli and chloroplast. The expressed moricin was purified using Ni columns and SUMOase, and the antibacterial activity of the purified moricin was confirmed using an agar diffusion assay.

• Composites Research
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• v.20 no.5
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• pp.64-69
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• 2007

Matrix dominant properties of composites are largely degraded under harmful environments such as temperature and humidity. Therefore we should consider the harmful environmental factors in the design of an UAV integral fuel tank subjected to high temperature and high humidity. The harmful environment experiment was performed for carbon/epoxy composites made of a unidirectional prepreg USN175B, and a plain woven fabric prepreg WSN3. The immersion experiment was performed under $90^{\circ}C$. The specimens were tested when the weight gam of specimen was saturated. The specimens were tested under $74^{\circ}C$ to obtain tensile and inplane shear properties. The results showed that the matrix dominant properties were extremely degraded by hygrothermal environment. To consider the variability of load, the anti-optimization method was applied. By using this method, the worst load case was found by comparing the load convex model and stability boundary. The stability boundary was obtained by analysis of the integral wing fuel tank of UAV using degraded properties. To do this, it was known that the worst load case of the integral wing fuel tank was the hovering mode load case.

• Information Systems Review
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• v.20 no.4
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• pp.79-96
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• 2018

This study started by focusing on the internalization of the technology appraisal model into the credit rating model to increase the discriminative power of the credit rating model not only for SMEs but also for all companies, reflecting the items related to the financial stability of the enterprises among the technology appraisal items. Therefore, it is aimed to verify whether the technology appraisal model can be applied to identify high-stability SMEs in advance. We classified companies into industries (manufacturing vs. non-manufacturing) and the age of company (initial vs. non-initial), and defined as a high-stability company that has achieved an average debt ratio less than 1/2 of the group for three years. The C5.0 was applied to verify the discriminant power of the model. As a result of the analysis, there is a difference in importance according to the type of industry and the age of company at the sub-item level, but in the mid-item level the R&D capability was a key variable for discriminating high-stability SMEs. In the early stage of establishment, the funding capacity (diversification of funding methods, capital structure and capital cost which taking into account profitability) is an important variable in financial stability. However, we concluded that technology development infrastructure, which enables continuous performance as the age of company increase, becomes an important variable affecting financial stability. The classification accuracy of the model according to the age of company and industry is 71~91%, and it is confirmed that it is possible to identify high-stability SMEs by using technology appraisal items.