Mineralogy and Geochemistry of the Jeonheung and Oksan Pb-Zn-Cu Deposits, Euiseong Area

최선규,이재호,윤성택,소칠섭,Choi, Seon-Gyu,Lee, Jae-Ho,Yun, Seong-Taek,So, Chil-Sup The Korean Society of Economic and Environmental G 1992 자원환경지질 Vol.25 No.4

경북(慶北) 의성(義城)지역 연(鉛)-아연(亞鉛)-동광상(銅鑛床)(전흥(田興), 옥산(玉山) 광산)은 경상분지(慶尙盆地) 백악기(白堊紀) 퇴적암류내의 구조면을 충진한 열수(熱水) 석영-방해석 맥상(脈狀) 광체(鑛體)로 구성된다. 광화(鑛化)작용은 구조적으로 석영-유화물(硫化物)-유염(硫鹽)광물-적철석 정출기, barren 석영-형석 정출기, barren 방해석 정출기 등 3회로 구분된다. 광화(鑛化) I기(期)의 광석(鑛石)광물은 황철석, 황동석, 섬아연석, 방연석 및 Pb-Ag-Bi-Sb계 유염광물(硫鹽鑛物) 등으로서 두 광산의 광물조성은 유사하지만, 유비철석, 자류철석, 테트라헤드라이트, 철을 다량 함유하는(약 21 mole% FeS)섬아연석 등은 옥산(玉山)광산에서만이 산출된다. 변질대 집운모(緝雲母)에 의한 K-Ar 연령은 약 62 Ma로서, 광화(鑛化)작용이 인근 금성산(金城山) 칼데라 화산암류와 도처에 분포하는 산성암맥의 분출 및 관입 활동과 관련된 후기 백악기(白堊紀) 화성활동의 산물이었음을 지시한다. 광화(鑛化) I기(期) 광물정출은 0.7~6.3wt.% NaCl 상당염농도(相當閻濃度)를 갖는 광화유체(鑛化流體)로부터 > $380^{\circ}{\sim}240^{\circ}C$의 온도범위에서 진행되었고, 특히 동(銅)광물은 대부분 > $300^{\circ}C$의 고온에서 침전하였다. 유체포유물(流體包有物) 연구에 의하면, I기 연(鉛)-아연(亞鉛)-동(銅)광물의 침전은 비등(沸騰) 냉각(冷却) 희석(稀釋)등 비교적 복잡한 양식의 광액(鑛液)진화에 기인하였지만, 전흥(田興)광산의 경우 차가운 천수(天水)의 유입(流入)에 따른 냉각(冷却) 및 희석(稀釋)이 우세하였던 반면, 옥산(玉山)광산의 경우는 비등(沸騰)이 우세하게 진행되었다. 광화유체(鑛化流體)의 비등(沸騰)에 근거한 광화(鑛化)작용시의 압력은 초기 약 210 bar에서 후기 약 80 bar에 이르며, 이는 열수계(熱水系)가 정암압(靜岩壓)이 우세한 환경에서 정수압(靜水壓)이 우세한 환경으로 전이되었음을 지시하여 주고 따라서 광화심도(鑛化深度)는 약 900m로 추정된다. 유화물(硫化物)의 유황동위원소(硫黃同位元素) 조성 ($2.9{\sim}9.6$‰)에 근거한 초기 열수유체(熱水流體)의 전(全)유황동위원소값(${\delta}^{34}S_{{\Sigma}S}$)은 약 8.6‰이며, 이는 심부(深部) 화성원(火成源)의 유황이 퇴적암류내 sulfate (?)와 다소 혼합되었음을 나타내는 것으로 사료된다. 한편, 수속 및 산소동위원소 조성은 열수계(熱水系)내의 물이 대부분 천수(天水)로부터 기원하였음을 지시한다. 광물열역학(鑛物熱力學)적 고찰 결과, I기 광화유체(鑛化流體)의 온도 및 유황분압(硫黃分壓)의 변화는 두 광산에서 다소 상이하였다. 즉, 전흥(田興)광산의 경우 온도 감소와 더불어 유황분압(硫黃盆壓)은 황철석-적철석-자철석의 공존선을 따라 지속적으로 감소하였으나, 옥산(玉山)광산의 경우는 초기 황철석-자류철석 공존환경으로부터 후기 황철석-적철석-자철석의 공존환경으로 전이하였다. 한편, 차고 산화(酸化) 상태인 천수(天水)가 광액(鑛液)중에 혼입(混入)됨에 따라 광액의 산소분압(酸素盆壓)은 점차 증가하였다. 동(銅)광물의 침전은 주로 광화유체(鑛化流體)의 냉각에 따른 동염화복합체(銅鹽化複合體)($CuCl^{\circ}$)의 용해도 감소에 기인하였으리라 고려된다. 이러한 냉각 작용은 전흥(田興)광산의 경우 주로 천수혼입(天水混入)에 따른 결과였지만, 옥산(玉山)광산의 경우는 주로 광화유체(鑛化流體)의 비등(沸騰)에 기인하였다. Lead-zinc-copper deposits of the Jeonheung and the Oksan mines around Euiseong area occur as hydrothermal quartz and calcite veins that crosscut Cretaceous sedimentary rocks of the Gyeongsang Basin. The mineralization occurred in three distinct stages (I, II, and III): (I) quartz-sulfides-sulfosalts-hematite mineralization stage; (II) barren quartz-fluorite stage; and (III) barren calcite stage. Stage I ore minerals comprise pyrite, chalcopyrite, sphalerite, galena and Pb-Ag-Bi-Sb sulfosalts. Mineralogies of the two mines are different, and arsenopyrite, pyrrhotite, tetrahedrite and iron-rich (up to 21 mole % FeS) sphalerite are restricted to the Oksan mine. A K-Ar radiometric dating for sericite indicates that the Pb-Zn-Cu deposits of the Euiseong area were formed during late Cretaceous age ($62.3{\pm}2.8Ma$), likely associated with a subvolcanic activity related to the volcanic complex in the nearby Geumseongsan Caldera and the ubiquitous felsite dykes. Stage I mineralization occurred at temperatures between > $380^{\circ}C$ and $240^{\circ}C$ from fluids with salinities between 6.3 and 0.7 equiv. wt. % NaCl. The chalcopyrite deposition occurred mostly at higher temperatures of > $300^{\circ}C$. Fluid inclusion data indicate that the Pb-Zn-Cu ore mineralization resulted from a complex history of boiling, cooling and dilution of ore fluids. The mineralization at Jeonheung resulted mainly from cooling and dilution by an influx of cooler meteoric waters, whereas the mineralization at Oksan was largely due to fluid boiling. Evidence of fluid boiling suggests that pressures decreased from about 210 bars to 80 bars. This corresponds to a depth of about 900 m in a hydrothermal system that changed from lithostatic (closed) toward hydrostatic (open) conditions. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S=2.9{\sim}9.6$ per mil) indicate that the ${\delta}^{34}S_{{\Sigma}S}$ value of ore fluids was ${\approx}8.6$ per mil. This ${\delta}^{34}S_{{\Sigma}S}$ value is likely consistent with an igneous sulfur mixed with sulfates (?) in surrounding sedimentary rocks. Measured and calculated hydrogen and oxygen isotope values of ore-forming fluids suggest meteoric water dominance, approaching unexchanged meteoric water values. Equilibrium thermodynamic interpretation indicates that the temperature versus $fs_2$ variation of stage I ore fluids differed between the two mines as follows: the $fs_2$ of ore fluids at Jeonheung changed with decreasing temperature constantly near the pyrite-hematite-magnetite sulfidation curve, whereas those at Oksan changed from the pyrite-pyrrhotite sulfidation state towards the pyrite-hematite-magnetite state. The shift in minerals precipitated during stage I also reflects a concomitant $fo_2$ increase, probably due to mixing of ore fluids with cooler, more oxidizing meteoric waters. Thermodynamic consideration of copper solubility suggests that the ore-forming fluids cooled through boiling at Oksan and mixing with less-evolved meteoric waters at Jeonheung, and that this cooling was the main cause of copper deposition through destabilization of copper chloride complexes.

Compositional Variations of Arsenopyrite from Gold-Silver Deposits in Korea

최선규,최인식,Choi, Seon-Gyu,Choi, In-Sik The Korean Society of Economic and Environmental G 1998 자원환경지질 Vol.31 No.2

한국의 금은광화작용은 쥬라기 대보화성활동 (121~183 Ma) 및 백악기 불국사화성활동 (60~110 Ma)과 밀접한 연관성을 보이며, 이러한 열수광맥형 금은 광산에서 산출된 유비철석은 광물공생관계 또는 생성환경에 따라 현저한 조성 변화를 나타내고 있다. 쥬라기 금광단일형 광상에서 산출된 유비철석은 비교적 높은 As함량 (29.68~33.46 atomic %)으로 균질한 조성을 나타내며, 유비철석 지질온도계에 적용하면 생성온도 및 유황분압은 $370{\sim}450^{\circ}C$와 $10^{-8}{\sim}10^{-6}$이다. 또한 백악기 금은혼합형 광상과 은광단일형 광상의 유비철석을 쥬라기 광상에 비하여 상대적으로 심한 조성변화 (27.47~32.74 atomic %)를 보이며, $25{\sim}30^{\circ}C$ 및 $10^{-12}{\sim}10^{-10}$의 환경 조건하에서 정출된 것으로 추정된다. 한편, 금은광맥의 산출상태, 유비철석 지질온도계, 에렉트럼-섬아연석 지질온도계, 유체포유물 연구자료 및 화성암의 정체심도 등을 종합적으로 비교검토한 결과, 쥬라기 금광화작용 (Group IIA)은 심부조건 (약 4~5 kbar)에서 $300{\sim}500^{\circ}C$의 정출환경에서 진행되었지만, 백악기 금은광화작용 (Group III, IV, V)은 1 kbar 미만의 천부조건하에서 $170{\sim}370^{\circ}C$의 온도조건하에서 형성된 것으로 사료된다. The gold-silver mineralizations in Korea are closely related to Jurassic Daebo igneous activity (121 and 183 Ma) and Cretaceous Bulgugsa igneous activity (60 and 110 Ma). A compilation and re-evaluation of chemical data in arsenopyrite suggest that the As contents vary, reflecting different genetic environments or mineral assemblages. The gold-silver vein deposits from various mineralized area were investigated using arsenopyrite geothermometer. Arsenopyrites from the Jurassic Au-dominant deposits are distinct by high As contents (29.68~33.46 atomic %) with narrow variations, equivalent to a temperature range of $370{\sim}450^{\circ}C$ and a sulfur fugacity of about $10^{18}-10^{-6}$ atm. On the contrary, arsenopyrites from the Cretaceous Au-Ag and Ag-dominant deposits show a wider range in atomic % As composition of 27.47-32.74. They may have formed at temperatures of $250{\sim}350^{\circ}C$ and about $f_{S_2}=10^{-12}-10^{-10}$ atm. The data of arsenopyrite geothermometer, electrum-sphalerite geothermometer, fluid inclusions, vein morphology and emplacement depth of igneous rocks indicate that the gold mineralizations of Group IIA occurred at temperatures between 300 and $500^{\circ}C$ at depth of several tens km or more (about 4-5 kbar), and the gold-silver deposits of Groups III, IV and V were formed at a temperature range of about $170{\sim}370^{\circ}C$ under the shallow environment (<1 kbar).

Contrasting Styles of Gold and Silver Mineralization in the Central and Southeastern Korea

최선규,최상훈,Choi, Seon-Gyu,Choi, Sang-Hoon The Korean Society of Economic and Environmental G 1995 자원환경지질 Vol.28 No.6

한반도 중부지역과 동남부지역에 분포하는 금-은 광상들의 광화작용은 쥐라기 중기로부터 백악기 말기에 걸쳐서 진행되었으며, 이들 광상은 유행별로 산출지역 및 산출시기에 연관된 지질학적 지화학적 생성환경의 차이를 나타내고 있다. 중부지역 금-은 광상은 북동-남서의 방향성을 갖고 산출분포하는 중생대 화강암류 및 주변 선캠브리아기 변성암류내에 분포하지만, 동남부지역 금-은 광상은 백악기 퇴적암 및 화산암류내에 주로 배태되고 있다. 이는 한반도 대표적인 화성활동인 쥐라지 대보화성활동 및 백악기 불국사 화성활동과 각각 밀접한 성인적 연관성을 시사하고 있다. 이러한 각 광상들의 광화작용 특성(광물공생관계, 조직, 구조 등)과 연대측정결과 및 지질학적 분포특성은 쥐라가 중기로부터 백악기 말기에 이르기까지 광상형성과 연관된 열수유체의 성인적 차이를 의미하고 있다. 즉, 쥐라기로부터 초기 백악기에는 금광단일형 광상의 광화작용이 우세하게 진행되었으나, 후기 백악기에 이르면서 금-은혼합형광상 및 은광단일형 광상의 광화작용이 우세하게 야기되었음을 알 수 있다. 쥐라기 금광단일형 광상들은 괴상의 맥상 산출특성 및 단순한 광석 광불 공생관계를 보여주는 단성광맥으로 높은 fineness 값을 나타내지만, 백악기 금-은혼합형 광상과 은광단일형 광상은 다양하고 복잡한 구조 및 조치특성 갖는 복성 광맥내에 함은황인 및 황화광물과 함은tellurides 및 자연은 등을 포함하는 등 상대적으로 복잡한 광석광물 공생과계를 보여준다. 한편 황화광물의 지질온도계와 유체포유물 연구의 결과등에 의하면 백악기 금-은혼합형 광상과 은광단일형 광상은 천부(<0.5 kb)에서 천수가 우세한 광화유체로부터 $200^{\circ}{\sim}350^{\circ}C$ 온도조건하에서 주된 광화작용이 진행되었지만, 쥐라기 금광단일형 광상은 마그마기원의 열수용액으로부터 고온$(300^{\circ}{\sim}500^{\circ}C)$ 및 고압$({\approx}4-5kb)$의 생성환경하에서 광화작용이 진행되었음을 시사한다. Two distinct precious-metal mineralizations actively occur at central and southeastern Korea which display consistent relationships among geologic, geochemical and genetic environments. A large number of preciousmetal vein deposits in the central Korea occur in or near Mesozoic granite batholiths elongated in a NE-SW direction. Whereas, gold and/or silver deposits in the southeastern Korea occur within Cretaceous volcanic and sedimentary rocks. However, most of the precious-metal deposits in the southeastern Korea show characteristics of the silver-rich deposits than the gold-rich deposits in the central Korea. Two epochs of main igneous activities are recognized: a) Jurassic Daebo igneous activity between 121 and 183 Ma, and b) Cretaceous Bulgugsa igneous activity between 60 and 110 Ma. Precious-metal mineralization took place between 158 and 71 Ma, coinciding with portions of the two magmatic activities. Contrasts in the style of mineralization, together with radiometric age data and differences in geologic settings reflect the genetically variable natures of hydrothermal activities from middle Jurassic to late Cretaceous time. The compilation and re-evaluation of these data suggest that the genetic types of hydrothermal precious-metal vein deposits in the central and southeastern Korea varied with time. The Jurassic and early Cretaceous mineralizations are characterized by the Au-dominant type, but tend to change to the Au-Ag and/or Ag-dominant types at late Cretaceous. The Jurassic Au-dominant deposits commonly show several characteristics; prominent associations with pegmatites, simple massive vein morphologies, high fmeness values in ore-concentrating parts, and a distinctively simple ore mineralogy such as Fe-rich sphalerite, galena, chalcopyrite, Au-rich electrum, pyrrhotite and/or pyrite. The Cretaceous precious-metal deposits are generally characterized by some- features such as complex vein morphologies, low to medium fmeness values in the ore concentrates, and abundance of ore minerals including Ag sulfosalts, Ag sulfides, Ag tellurides and native silver. Mineralogical and fluid inclusion studies indicate that the Jurassic Au-dominant deposits in the central area were formed at the high temperature (about $300^{\circ}$ to $500^{\circ}C$) and pressure (about 4 to 5 kbars), whereas mineralizations of the Cretaceous Au-Ag and Ag-dominant deposits were occurred at the low temperature (about $200^{\circ}$ to $350^{\circ}C$) and pressure (<0.5 kbars) from the ore fluids containing more amounts of less-evolved meteoric waters.

충청도(忠淸道) 동북부(東北部) 태창(泰昌)·보연(寶蓮), 금왕(金旺) 광산(鑛山)의 금은광화작용(金銀鑛化作用)

최선규,박노영,박성원,Choi, Seon Gyu,Park, No Young,Park, Sung Won 대한자원환경지질학회 1986 자원환경지질 Vol.19 No.no.spc

A number of auriferous veins occur in the Precambrian metamorphic terrain from Chungju to Mugeug district. These gold (-silver) deposits consist mainly of the fissure-filling quartz veins intruding the Precambrian gneiss or schist and Jurassic or Cretaceous granite. These gold (-silver) deposits can be 'divided into two mineralization epochs, (a) gold-rich veins related to Daebo igneous activity, and (b) gold-silver veins related to Bulgugsa igneous activity. These two groups of ore deposits with different generation can be characterized by the mode of occurrence of ore vein and the ore mineral associations. The auriferous quartz veins of Taechang and Boryeon mines associated with late Jurassic igneous activity are massive in character, and show the simple mineral assemblages and low Ag/Au ratio in the ores, representing a single mineralization system. The ore minerals are predominantly quartz containing minor or trace amonts of pyrrhotite, sphalerite, galena, pyrite, chalcopyrite and electrum. Electrum is closely associated with pyrrhotite and has chemical compositions from 61.4 to 78.5 atomic % Au. Fluid inclusion data suggest that ore minerals were deposited at temperatures between 238 and $390^{\circ}C$ from $CO_2$-rich fluids. The gold and/or silver-bearing quartz veins of Geumwang mine related to middle Cretaceous igneous activity are characterized by the multistage history, diverse mineral assemblages with high Ag/Au ratio in the ores. The ores of Geumwang mine have two contrasting mineral assemblages (1) pyrite+galena+sphalerite+arsenopyrite+electrum+argentite, representing the higher gold mineralization, and (2) pyrite+chalcopyrite+ galena +sphalerite+ arsenopyrite+silver sulfosalts+ electrum+ native silver+argentite, representing the higher silver mineralization. Electrum is closely associated with pyrite and has chemical compositions from 11.2 to 49.9 atomic % Au. The depositional environment during the higher gold mineralization can be estimated as the range of both temperature and sulfur fugacity, T= $200{\sim}300^{\circ}C$, log f ($S_2$) = $10^{-10}{\sim}10^{-15}$. The higher silver mineralization may be interpreted to have formed a range of falling temperature ($150{\sim}200^{\circ}C$) and low sulfur fugacity($10^{-10}{\sim}10^{-15}$). These temperature data are consistent with homogenization temperatures of fluId inclusions in quartz. Thus, the gold veins related to the Daebo igneous activity may be formed by the environment of higher temperature and pressure than the gold-silver veins associated with the Bulgugsa igneous activity.

기고 - 출판을 위한 글쓰기: 건축사의 의무

최선규,Choi, Sun-Kyu 대한건축사협회 2022 建築士 Vol.637 No.-

비보강받침접합의 용접강도와 설계도표

최선규,유정한,이강민,박재우,Choi, Sun-Kyu,Yoo, Jung-Han,Lee, Kang-Min,Park, Jai-Woo 한국강구조학회 2012 韓國鋼構造學會 論文集 Vol.24 No.2

Unstiffened seated connections (USC) ensure easy installation and safety during erection, thereby making the process more economical. USCs consist of a seat angle for carrying the beam's reactions and a top angle to provide beam stability. These angles are bolted or welded to the beam and supporting member. This paper sought to propose a design table for the weld strength of such connections obtained from the elastic vector method (EVM) and the instantaneous center-of-rotation method (ICM) in terms of calculating the eccentricity. Also, the proposed design table is compared with both AISC and KBC specifications. 비보강받침접합(Unstiffened Seated Connection, USC)은 시공의 편의성과 설치시의 안정성 및 경제성이 있는 단순접합의 한 종류이다. 비보강받침접합은 하부ㄱ형강과 상부ㄱ형강으로 구성되며 하부ㄱ형강은 보의 단부반력전체를 지지하며, 상부ㄱ형강은 보의 안정을 위하여 설치한다. 상부와 하부ㄱ형강은 볼트 또는 용접에 의해 보와 지지부재에 접합된다. 본 연구에서는 비보강받침접합의 용접강도에 대한 실용적인 설계절차와 함께 용접부의 편심계산시 탄성벡터법(EVM)과 순간회전중심법(ICM)으로 소요지압길이에 근거한 설계도표를 제안하였다. 또한 제안한 설계방법에 의한 용접강도를 AISC와 KBC기준에 따라 비교하였다.

Gold-Silver Mineralization of the Geojae Area

최선규,지세정,윤성택,고용권,유재신,Choi, Seon-Gyu,Chi, Se-Jung,Yun, Seong-Taek,Koh, Yong-Kwon,Yu, Jae-Shin The Korean Society of Economic and Environmental G 1989 자원환경지질 Vol.22 No.4

경남거제지역 금(金)-은광상(銀鑛床)들은 후기 백악기 안산암류와 화강섬록암(83 m.y.)내의 열극을 충진한 함금(含金)-은(銀) 열수맥상(熱水脈狀) 광체로 구성된다. 열수광화작용(熱水鑛化作用)은 구조운동에 의하여 시기적으로 3회에 걸쳐 진행되었다. 초기 제$370^{\circ}C$의 고온에서 후기 $200^{\circ}C$에 이르는 제 I, II 광화기(鑛化期)에서는 각기 상이한 열수계(熱水系)에 의하여 석영, 유화물이 침전하였으며, $320^{\circ}C$를 전후로 하여 광화류체(鑛化流體)의 비담(沸膽)현상이 일어났다. 제 I, II 광화작용(鑛化作用)시의 압력은 <100기압이고, 심도는 500~1,250m였다. 금(金)-은(銀)의 주광화시기(主鑛化時期)인 광화(鑛化) I 기(期)의 공생광물에 대한 유체포유물(流體包有物) 및 광물열수학적(鑛物熱水學的) 연구에 의하면, 황철석, 섬아연석, 황동석은 $290^{\circ}C$ 이상의 고온에서 비담작용(沸膽作用)과 동시에 정출하였고, 사면동석, 에렉트렘, 스튜자이트는 금(金)-유황종(硫黃種)의 농도가 $10^{-3}{\sim}10^{-4}$molal, 상당염농도(相當鹽濃度)가 2~6wt.% NaCl인 광화유체(鑛化流體)로부터 $220{\sim}260^{\circ}C$, 유황 및 산소분압이 각각 $10^{-11.8}{\sim}10^{-14}$, $10^{-35}{\sim}10^{-36}$ atm인 물리 화학적 환경하에서 침전하였다. 균질화(均質化) 온도와 염농도(相當鹽濃度)와의 관계는 천수류입(天水流入)에 의한 광화류체(鑛化流體)의 냉각(冷却) 및 희석(稀釋)작용이 광석광물 침전의 주된 메키니즘이었음을 지시해 주며, 유체내(流體內) 환원(還元) 유황종(硫黃種)($H_2S$)의 감소에 따른 금류화복합체(金硫化複合體)($Au(HS)_2$) 의 파괴로 금(金)의 침전이 유도되었으리라 사료된다. 유황 및 탄소, 산소 안정동위원소(安定同位元素) 연구(硏究)결과, 광화류체내(鑛化流體內)의 유황 및 탄소는 심부화성(深部火成)기원이었고, 방해석의 산소 안정동위원소(安定同位元素)값으로부터 열수계(熱水系)에서 천수(天水)가 지배적인 역할을 하였으리라 사료된다. The electrum-silver-sulfide mineralization of the Geojae island area was deposited in three stages (I, II, and carbonate) of quartz and calcite veins that crosscut Late Cretaceous volcanic rocks and granodiorite(83 m.y.). Stages I and II were terminated by the onset of fractunng and breCCIation events. Fluid inclusion data suggest that the gold-sulfide-bearing stages I and II each evolved from an initial high temperature( near $370^{\circ}C$) to a later low temperature(near $200^{\circ}C$). Each of those stages represented a separate mineralizing system which cooled prior to the onset of the next stage. The relationship between homogenization temperature and salinity in stages I and II suggests a complex history of boiling, cooling and dilution. Evidence of boiling indicates a pressure of < 100 bars, corresponding to a depth of 500 to 1,250m assummg hthostatlc and hydrostatic pressure regimes, respectively. Fluid inclusion and mineralogical evidence suggest that the electrum-silver mineralization was deposited at a temperature of $220-260^{\circ}C$ from ore fluids with salinities between 1.9 and 8.1 equivalent wt.% NaCl. Total sulfur concentration is estimated to be $10^{-3}$ to $10^{-4}$ molal. The estimated $fs_2$ and $fo_2$ range from $10^{-11.8}$ to $10^{-14}$ atm and $10^{-35}$ to $10^{-36}$ atm, respectively. The chemical conditions indicate that the dominant sulfur species in the ore forming fluids was a reduced form($H_2S$). Rapid cooling and dilution of ore-forming fluids by mixing with less-evolved meteoric waters led to gold-silver deposition through the breakdown of the bisulfide complex($Au(HS)_2$) as the activity of $H_2S$ decreased.

SiO₂/Si 및 Si 기판에 rf magnetron sputtering법으로 증착된 적외선 센서용 La_0.7Sr_0.3MnO₃ CMR 박막 저항체 특성연구

최선규,유병곤,류호준,박형호,Choi, Sun-Gyu,Reddy, A. Sivasankar,Yu, Byoung-Gon,Ryu, Ho-Jun,Park, Hyung-Ho 한국진공학회 2008 Applied Science and Convergence Technology Vol.17 No.2

$La_{0.7}Sr_{0.3}MnO_3$ 박막을 rf 마그네트론 스퍼터를 이용하여 챔버 내 산소가스유량비를 0, 40, 80 sccm 으로 조절하고 후열처리 공정 없이 기판온도를 $350^{\circ}C$로 유지하면서 $SiO_2$/Si(100) 및 Si(100) 기판에 증착하였다. 증착된 $La_{0.7}Sr_{0.3}MnO_3$ 박막은 $SiO_2$/Si(100), Si(100) 기판 모두 (100), (110), (200)면을 갖는 polycrystalline 상태였으며, oxygen flow rate이 증가함에 따라 박막의 grain size가 증가하였다. 증가되는 grain size로 인하여 grain boundary가 감소하였고 따라서 높은 oxygen flow rate에서 증착된 박막은 면저항이 감소하는 현상을 나타내었다. $SiO_2$/Si 기판과 Si 기판에 증착된 LSMO 박막의 TCR 값은 약 -2.0 $\sim$ -2.2%를 나타내었다. $La_{0.7}Sr_{0.3}MnO_3$ films were deposited on $SiO_2$/Si and Si substrates annealed at $350^{\circ}C$ by rf magnetron sputtering. The oxygen gas flow rates were varied as 0, 40, and 80 sccm. Without post annealing process, $La_{0.7}Sr_{0.3}MnO_3$ thin films on $SiO_2$/Si and Si substrates were polycrystalline with (100), (110), and (200) growth planes. The grain size of $La_{0.7}Sr_{0.3}MnO_3$ thin films was increased with increasing oxygen gas flow rate. The sheet resistance of $La_{0.7}Sr_{0.3}MnO_3$ thin films was decreased with oxygen flow rate due to the increased grain size which induced a reduction of grain boundary. TCR (temperature coefficient of resistance) values of $La_{0.7}Sr_{0.3}MnO_3$ thin films were obtained from -2.0% to -2.2%.

강원도 옥계 금광상에 관한 광물학적·지화학적 연구

최선규,최상훈,이현구,Choi, Seon-Gyu,Choi, Sang-Hoon,Lee, Hyun Koo 대한자원환경지질학회 1997 자원환경지질 Vol.30 No.1

Gold mineralization of the Ogkye gold mine was deposited mainly in quartz veins up to 150 cm wide which occupy fissures in Cambrian Pungchon limestone. Ore minerals are relatively simple as follows: pyrite, arsenopyrite, pyrrhotite, sphalerite, electrum and galena. On the basis of the Ag/Au ratio on ore grades, mode of occurrence and assoicated mineral assemblages, the Ogkye gold deposit can be classified as pyrite-type gold deposit (Group IIB). Fluid inclusion data indicate that ore minerals were deposited between $400^{\circ}$and $230^{\circ}C$ from relatively dilute fluids (0.2 to 7.3 wt.% eq. NaCl) containing $CO_2$. The ore mineralization resulted from a complex history of $CO_2$ effervescence and local concomitant boiling coupled with cooling and dilution of ore fluids. Gold deposition was likely a result of decrease of sulfur activity caused by sulfide deposition and/or $H_2S$ loss accompanying fluid unmixing. Sulfur isotope compositions of sulfide minerals (${\delta}^{34}S=3.5{\sim}5.9$‰) are consistent with ${\delta}^{34}S_{H_2S}$ value of 4.8 to 6.1‰, suggesting mainly an igneous source of sulfur partially mixed with wall-rock sulfur.

토양환경 변화와 접지저항의 상관관계 분석을 통한 접지 저항값 예측 연구

최선규,이규영,문영호,심건보,Choi, Sun-Kyu,Lee, Kyu-Young,Moon, Young-Ho,Shim, Keon-Bo 한국전력공사 2020 KEPCO Journal on electric power and energy Vol.6 No.1

The purpose of this paper is to improve the grounding point measurement method for the maintenance of the earth resistance of the distribution line. This study defines the correlation among humidity of the soil, the earth resistivity and the grounding resistance. Based on the results of the study, the grounding resistance value measurement should be limited to the location where the earth resistivity change is large, and the measurement time and cost can be greatly reduced.