• Korean Journal of Mineralogy and Petrology
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• v.37 no.3
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• pp.139-153
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• 2024

Recently, resources-rich advanced countries are putting more effort into mineral resource exploration as mineral resource depletion worsens along with deepening resource nationalism regarding mineral resources. Therefore, one of the methods used to explore mineral resources is to explore through the chemical composition of mineral. Pyrite, which is formed throughout the mineralization process and regardless of the mineral commodity type, is widely used as major geochemical indicator in mineral deposit exploration using content and list of trace elements in the pyrite. In this paper, the author aims to report on indicator elements that can be used when exploring lead-zinc orebody by studying the occurrence and chemical composition of pyrites from wallrock, wallrock alteration and lead-zinc orebody in the Janggun lead-zinc deposit. This deposit is hydrothermal replacement deposit formed by reaction of lead and zinc-bearing hydrothermal fluid and Paleozoic Janggum limestone formation. The wallrock alteration that is remarkably recognized with Pb-Zn mineralization at this hydrothermal replacement orebody consists of mainly rhodochrositization with minor of dolomitization, pyritization, sericitization and chloritization. Pyrite, which is occurred from wallrock, wallrock alteration, and lead-zinc orebody, is classified into three types (Py I type, Py II type, and Py III type) based on the texture, occurrence and paragenetic relationship. Pyrite on the basis of paragenetic sequence are as followed : Py I type (wallrock and wallrock alteration) → Py II type (wallrock alteration and Pb-Zn orebody) → Py III type (wallrock alteration and Pb-Zn orebody). Trace elements with a large content change in pyrite by all types are Mn, As, Ag, Sb and Pb elements, but trace elements with a small content change in pyrite are Zn, Cu, Cd, Se, Te, Co, Ni, Au, In and Sn elements. The substitution of these elements in all pyrite types is as followed: Fe²⁺↔Co²⁺ substitution (Py I type), 3Fe²⁺↔Ag¹⁺+(Mn²⁺+Ni²⁺+As²⁺)+(As3++Sb3+) substitution (Py II type) and 3Fe²⁺↔Ag¹⁺+(Mn²⁺+As²⁺+Pb²⁺)+(Mn³⁺+As³⁺+Sb³⁺), S^1-↔(As^1-+Sb^1-) substitution (Py III type). This means that Mn, As, Sb, Ag and Pb elements were enriched during evolution of hydrothermal fluid. Therefore, based on the above research results, pyrite is a useful mineral for exploration of lead-zinc orebody. And when exploring lead-zinc orebody with similar geological conditions, lead-zinc orebody is explored through the enrichment of as indicator elements.

• Korean Journal of Food Science and Technology
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• v.42 no.6
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• pp.699-704
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• 2010

Rapeseed oil was stored under different conditions such as in the dark, with UV treatment, and with prooxidantscytochrome C and copper ion. The rapeseed oils stored at different temperatures were analyzed by a mass spectrometrybased electronic nose and discriminant function analysis (DFA). Volatile components in the rapeseed oil increased with storage time, and the discriminant function first score (DF1) moved from a positive position to a negative position as storage time increased. Changes in DF1 were higher under UV treatment than under the dark condition (DF1: $r^2$=0.9481, F=307.03). The different DF1 values (F1) under the dark condition were 0.099, 0.187, and 0.278 as storage temperature increased. The different values under UV treatment were 0.554, 0.588, and 0.542, as storage temperature increased from 4 to $26^{\circ}C$. As concentrations of prooxidants copper ion and cytochrome C increased, amounts of volatile components also increased. These were confirmed by DFA. Furthermore, changes in responses at each ion fragment agreed with reported results for GC/MS, which formed after rancidity of the oil, including pentane, pentanal, 1-pentanol, hexanal, n-octane, 2-hexenal, heptanal, 2-heptenal, decane, 2-octenal, undecane, and dodecane.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1617-1620
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• 2013

The widely-used measurement methods for conductivity of non-magnetic metals are van der Pauw method, Two Point Probe method and Eddy Current method. Among them a more simpler and easier method is the Eddy Current method and an instrument using the method is a Conductivity Meter which can measure a conductivity by contacting its probe on a sample surface. However, conductivity standards are essentially needed to confirm the meter's performance or to calibrate it. In this study, six kinds of the standards which are made of Cu, Al-1, Al-2, brass, Zn and SUS-316 are developed and conductivity ranges for the standards are 2.27 %IACS ~ 101.6 %IACS with measurement uncertainty of less than 0.3 %.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.62.1-62.1
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• 2010

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성 및 조성 조절을 통한 밴드갭 조절이 용이해 고효율 박막 태양전지로 각광 받고 있다. 또한 CIGS 태양전지는 기존의 유리기판 대신 유연한 기판을 사용해 flexible 태양전지 제조가 가능하다. 이러한 유연기판은 보통 stainless steel과 같은 금속 기판이 많이 사용되는데 기존의 soda-lime glass 기판과는 달리 금속기판에는 Na이 첨가되어 있지 않아 별도의 Na첨가를 필요로 한다. Na은 CIGS 흡수층의 조성조절을 용이하게 하여 태양전지의 변환 효율을 향상시키는 역할을 한다. 본 연구에서 기판은 Na이 첨가되어있지 않은 corning glass를 사용 하였으며 NaF를 이용해 Mo가 증착된 기판에 NaF의 두께를 달리하며 증착해 CIGS 흡수층의 grain 사이즈를 비교 하였으며 그 후 태양전지 소자를 제조해 광전특성을 분석하였다. 후면 전극으로 약60nm 두께의 Mo를 DC Sputtering 방법을 이용해 증착 하였다. buffer층으로는 약 50nm의 CdS층을 CBD방법을 이용하여 제조 하였으며 TCO 층으로 약 50nm의 i-ZnO와 약 450nm의 Al-ZnO를 RF Sputtering방법으로 증착 하였다. 마지막으로 앞면 전극으로 약 $1{\mu}m$의 Al을 Thermal Evaporation방법으로 증착하였다. 태양전지 소자의 면적은 $0.49cm^2$로 효율을 비교 분석하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.4
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• pp.241-250
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• 1997

The velocity dispersion of surface acoustical wave(SAW) of Si layer/mesh Au/Si substrate was measured by the frequency analysis technique of backward radiation at liquid/solid interface. The difference of backward radiation patterns depending on used transducers (2, 5, 10MHz) confirmed that the backward radiation phenomenon was caused by the energy radiation from SAW generated in surface region. An ultrasonic goniometer was constructed to measure continuously the angular dependence of backscattered intensity. The angular dependences of backward radiation(5MHz) were measured for Ni layer/Al substrate specimens that were bonded by epoxy involving different content of Cu powder. It was known that the width and pattern of backward radiation had informations such as the velocity dispersion, bonding quality and structure of surface region.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.433-433
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• 2013

Graphene, $sp^2$-hybridized 2-Dimension carbon material, has drawn enormous attention due to its desirable performance of excellent properties. Graphene can be applied for many electronic devices such as field-effect transistors (FETs), touch screen, solar cells. Furthermore, indium tin oxide (ITO) is commercially used and sets the standard for transparent electrode. However, ITO has certain limitations, such as increasing cost due to indium scarcity, instability in acid and basic environments, high surface roughness and brittle. Due to those reasons, graphene will be a perfect substitute as a transparent electrode. We report the graphene synthesized by inductive coupled plasma enhanced chemical vapor deposition (ICP-PECVD) process on Cu substrate. The growth was carried out using low temperature at $400^{\circ}C$ rather than typical chemical vapor deposition (CVD) process at $1,000^{\circ}C$ The low-temperature process has advantage of low cost and also low melting point materials will be available to synthesize graphene as substrate, but the drawback is low quality. To improve the quality, the factor affect the quality of graphene was be investigated by changing the plasma power, the flow rate of precursors, the scenario of precursors. Then, graphene film's quality was investigated with Raman spectroscopy and sheet resistance and optical emission spectroscopy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.879-884
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• 2001

In this paper, the structural and dielectric properties of (Sr$_{l-x}$Ca$_{x}$)TiO$_3$ (0$\leq$x$\leq$0.2) -based grain boundary layer ceramics were investigated by XRD, SEM and HP4194A. The ceramics were fabricated by the conventional mixed oxide method. The sintering temperature and time were 1420~152$0^{\circ}C$ and 4 hours, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca. The average grain size was increased with increase of sintering temperature. The relative density of all specimens was 96~98%. The 2nd Phase formed by the thermal diffusion of CuO from the surface leads to very excellent dielectric properties, that is, $\varepsilon$$_{r}$>50000, tan $\delta$<0.05, $\Delta$C<$\pm$10%. The appropriate Ca content was under 15 ㏖%.s under 15 ㏖%.%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.230-235
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• 2003

In the micro hole punching, the size and shape of burr and burnish zone are very important factors to evaluate quality of micro holes which depend on punch-die clearance, stain rate, workpiece material and etc. To get micro holes with small burr and wide burnish zone for industrial demands, not only the parametric study but also a study on fracture behavior in shear band are necessary. In this study, 100 $\mu\textrm{m}$, 25 $\mu\textrm{m}$ micro holes in diameter were fabricated on brass (Cu63/Zn37) and SUS 316 foils as aspect ratio 1:1, and the characteristics of micro holes was investigated comparing with man holes over several mm by scanning electron microscopic views and section views. Like macro hole, micro hole is also composed of 4 portions, rollover, burnish zone, fracture zone and it shows similar fracture behavior in shear band, but？ by high strain rate (10$^2$∼ 10$^3$s$\^$-1/) unlike macro hole fabrication and increment of relative grain size several different results are shown.

• The Korean Journal of Nuclear Medicine
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• v.39 no.4
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• pp.215-223
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• 2005

Current interest in the regioselective N-functionalization of tetraazacycloalkanes (cyclen and cyclam) stems mainly from their complexes with radioactive metals for applications in diagnostic ($^{64}Cu,\;^{111}In,\;^{67}Ga$) and therapeutic ($^{90}Y$) medicine, and with paramagnetic ions for magnetic resonance imaging ($Gd^{+3}$). Selective methods for the N-substitution of cyclen and cyclam is a crucial step in most syntheses of cyclen and cyclam-based radiometal complexes and bifunctional chelating agents. In addition, mixing different pendent groups to give hetero-substituted cyclen derivatives would be advantageous in many applications for fine-tuning the compound's physical properties. So far, numerous approaches for the regioselective N-substitution of tetraazacycloalkanes and more specifically cyclen and cyclam are reported. Unfortunately, none of them are general and every strategy has its own strong points and drawbacks. Herein, we categorize numerous regioselective N-alkylation methods into three strategies, such as 1) direct substitution of the macrocycle, 2) introductiou of the functional groups prior to cyclization, and 3) protection/iunclionallrationideproteclion. Our discussion is also split into the methods of mono- and tri-functionalization and di-functionalizataion based on number of substituents. At the end, we describe new trials for the new macrocycles which iorm more stable metal complexes with various radiometals, and briefly mention the commercially available tetraazacycloalkanes which are used for the biconjugation of biomolecules.

• Journal of the korean society of oceanography
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• v.35 no.2
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• pp.89-97
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• 2000

The pyritization of heavy metals in Lake Shihwa sediments was investigated to determine sedimentary Pyrite-heavy metal associations influenced by various metal fractions, organic carbon, and total reduced sulfur. Parameters indicating the degree of heavy metal pyritization (DTMP) and degree of pyritization (DOP) were used to study the incorporation of heavy metals into the pyrite phase. The DOP levels ranged from 3.28-39.45%, showing wide differences among sampling stations. The levels were greater near the water gate and the center of the lake than near the industrial complex. The spatial pattern of the DOP levels was similar to the S/C ratio and also to the salinity. Based on the measured relationships between DOP and DTMP, heavy metals can be divided into three groups. In the first group was As, which showed a high affinity for pyrite. In the second group were Ni, Co and Cu, which showed a gradual increase in DTMP with increasing DOP. In the final group were Pb, Zn, Mn and Cr, which all showed a low DTMP with constant values with respect to DOP.