고출력 다이오드 레이저를 이용한 SKD11 표면 열처리 특성

최성대,정선환,양승철,김잠규 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

An experimental investigation with high power diode laser system was carried out to study the effect of surface heat treatment on the SKD11. The surface heat treatment characteristics of the laser beam were evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the Hardness were changed by beam size, focal length, feed rates. The micro grain structure was observed retained austenite grain at hardened zone and globular cementite grain at fine grain zone and base metal zone by optical microscopy. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected on the surface and the hardened surface intensity level was bigger than the unhardened surface. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.

DFSS에 의한 FPD용 높이 조절기구 설계

정선환,최성대,조규열 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

This study was carried out to minimize the lifting force and to design the slim sized frame of a height adjustment mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment as well as to achieve much slimmer frame for the pedestal. A tolerance analysis of 6 sigma was applied to achieve smooth lift at design stage not to change the tolerance specification of gap several times in a roller type of lifting mechanism at mass production stage. The specification of minimum gap and the target of production yield ratio were agreed with a quality team before tooling. A DFSS simulation on drawings had been done with reasonable tolerance and achievable standard deviation(σ) several times until the target spec of gap and yield ratio was met. Once tolerance and deviation(σ) were fixed tooling start was done successfully. A CAE method was applied to achieve a slim design. Design parameters were frozen when those parameters matched the reference strength data of standard model. Through those tolerance analysis and CAE simulation the number of tool modification was reduced and production yield ratio was raised up without arguing quality specification at production stage in the end.

UR 보조금 협정과 정보통신진흥기금의 개편방향

김동주,최선규 高麗大學校 産業開發硏究所 1995 産業開發硏究 Vol.4 No.-

MESOZOIC GARNITOIDS AND GOLD-SILVER MINERALIZATION IN KOREA

SEON-GYU CHOI,SANG JOON PAK,HONG JA SHIN 대한지질학회 2000 대한지질학회 학술대회 Vol.2000 No.

Mesozoic Geodynamics and Epithermal Mineralization in Korea

Seon-Gyu Choi,In-Chang Ryu,Soo-Meen Wee 대한지질학회 2003 대한지질학회 학술대회 Vol.2003 No.

Magnetite and scheelite-bearing skarns in Ulsan mine, Korea

Seon gyu Choi(崔善奎),Naoya Imai(今井直哉) 대한자원환경지질학회 1993 자원환경지질 Vol.26 No.1

경상분지 남동부에 위치한 울산광산은 석회암을 교대한 전형적인 calcareous skarn광상으로 FeㆍW광화작용 이외에도 Cu, Pb, Zn, As, Bi, Ni, Co, Cr, Ag, Sn, In, Te, Sb 등이 수반되는 다금속광화작용의 특성을 보여주고 있다. 본 광상은 직립에 가까운 파이프상 광체로 산출되며, 자철석과 함께 북측의 혼펠스와의 경계부근에 회중석이 부분적으로 광염되어 있다. 본 광상의 스카른대는 석회암 및 혼펠스를 교대한 괴상 스카른과 양자를 각기 절단하는 맥상스카른으로 구분된다. 괴상스카른은 석회암 기원의 스카른이 주체를 이루며, 이러한 스카른대는 규회석 스카른, 석류석 스카른, 단사휘석-석류석 스카른, 단사휘석 스카른으로 분류되며, 부분적으로 스카른대 주변부를 따라 거정질 방해석대가 존재하고 있다. 스카른 진화과정은 초기스카른 및 후기스카른의 두 시기로 분류되며, 초기스카른은 prograde한 스카른 생성시기로 초기에는 규회석, Mg-rich 단사휘석, Al-rich garnet가 주로 정출되며 광석광물은 거의 불모한 시기이나, 초기스카른의 말기로 진행됨에 따라 자철석과 회중석이 정출된다. 그리고, 후기스카른의 전반기까지는 Fe-rich 단사휘석, Fe-rich garnet와 함께 자철석ㆍ회중석이 연속적으로 정출되었으나, 후기스카른의 중기부터는 Ni, Co, As, Cu, Zn, Fe, Bi 등의 황화광물이 정출되는 다금속광화작용의 특징을 보인다. 또한, 최후기 열수작용시기에는 섬아연석과 방연석 등의 Base-metal 황화광물이 주로 정출되는 연ㆍ아연 광화작용의 양상을 나타낸다. 이러한 각 광화시기별 스카른 광물과 광석광물의 변화양상은 고온의 열수용액이 천부로 유출되는 과정에서 광화용액의 온도가 급격히 떨어진 결과 (telescope)에 기인된 것으로 사료된다. The Ulsan Fe-W deposit, which can be classified as a calcareous skarn deposit, is represented by ore pipe consisting principally of magnetite and lesser amounts of scheelite with minor sulphides, sulphosalts, arsenides, sulpharsenides, etc. At Ulsan mine, metasomatic processes of skarn growth may be divided broadly into two stages based on the paragenetic sequence of calc-silicate minerals and their chemical composition; early and late skarn stages. Early stage has started with the formation of highly calcic assemblages of wollastonite, diopsidic clinopyroxene and nearly pure grossular, which are followed by the formation of clinopyroxenes with salite to ferrosalite composition and grandite garnets with intermediate composition. Based on these calc-silicate assemblages, the temperatures of early skarn formations have been in the ranges of 550° to 450℃. The calc-silicate assemblages formed during the earlier half period of late skarn stage show the enrichment of notable iron and slight manganese, and the depletion of magnesium; clinopyroxenes are hedenbergitic, and grandite garnets are andraditic. The formation temperatures during this skarn stage are inferred to have been in the range of 430° to 470℃ at low Xco₂ by data from fluid inclusions of late andraditic garnets. The later half period of late skarn stage is characterized by the hydrous alteration of pre-existing minerals and the formation of hydrous silicates. The main iron-tungsten mineralization representing prominent deposition of magnetite immediately followed by minor scheelite impregnation has taken place at the middle of early skarn stage, while complex polymetallic mineralization has proceeded during and after the late skarn stage. Various metals and semimetals of Fe, Ni, Co, Cu, Zn, As, Mo, Ag, In, Sn, Sb, Te, Pb and Bi have been in various states such as native metal, sulphides, arsenides, sulphosalts, sulpharsenides and tellurides.

Petrology, geochronology and tectonic implications of Mesozoic high Ba–Sr granites in the Haemi area, Hongseong Belt, South Korea

Choi, Seon-Gyu,Rajesh, V. J.,Seo, Jieun,Park, Jung-Woo,Oh, Chang-Whan,Pak, Sang-Joon,Kim, Sung-Won Blackwell Publishing Asia 2009 The island arc Vol.18 No.2

<P>Abstract</P><P>Collision between the North and South China continental blocks began in the Korean peninsula during the Permian (290–260 Ma). The Haemi area in the Hongseong collision belt (proposed as the eastern extension in South Korea of the Dabie–Sulu collision zone of China) within the Gyeonggi Massif comprises post-collisional high Ba–Sr granite with intermediate enclaves that intruded into the Precambrian rocks. The intermediate enclaves have a shoshonitic affinity whereas the granite is a high-K calc-alkaline variety. The chondrite-normalized rare earth element (REE) pattern with relative enrichment of LREE over HREE and absence of a significant negative Eu anomaly typifies both enclaves and granite. Geochemical similarities of enclaves and granite are attributed to the involvement of enriched mantle sources in their genesis. However, dominant crustal components were involved in the formation of high Ba–Sr granites. A granite crystallization age of 233 ± 2 Ma was obtained from SHRIMP U–Pb zircon dating. This age is slightly younger than the Triassic collision event in the Hongseong Belt. Geochemical data, U–Pb zircon age, and regional tectonics indicate that the Haemi high Ba–Sr granite formed in a post-collisional tectonic environment. A Mesozoic post-collisional lithospheric delamination model can account for the genesis of high Ba–Sr granite in the Haemi area.</P>

忠淸道 東北部 泰昌ㆍ寶蓮, 金旺 鑛山의 金銀鑛化作用

Seon Gyu Choi(崔善奎),No Young Park(朴魯榮),Sung Won Park(朴性元) 대한자원환경지질학회 1986 자원환경지질 Vol.19 No.5

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℃ from CO₂-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=200~300℃, logf (S₂)=10⁻¹⁰~10⁻¹⁵. The higher silver mineralization may be interpreted to have formed a range of falling temperature (150~200℃) and low sulfur fugacity(10⁻¹⁵~10⁻¹⁸). These temperature data are consistent with homogenization temperatures of fluld 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.

忠淸北道 永同地域 金銀鑛床의 金銀鑛化作用에 관한 硏究

Seon Gyu Choi(崔善奎),Se Jung Chi(池世定),Sung Won Park(朴性元) 대한자원환경지질학회 1988 자원환경지질 Vol.21 No.4

Most of the gold (-silver) vein deposits at Yeongdong District are mainly distributed in the precambrian metamorphic rocks. Based on the Ag/Au total production and ore grade ratios, the chemical composition of electrum and the associated sulfides, the gold(-silver) deposits at Yeongdong District may be classified into 4 classes: pyrrhotite - type gold deposits( I), pyrite - type gold deposits (IT A; massive vein), pyrite - type gold deposits (II B; nonmassive vein) and argentite - type gold - silver deposits(III). The chemical study on electrum(including native gold) revealed that Au content (2.8 to 92.4 atomic%) of electrums varies very widely for different classes of deposits. The Au content of electrum associated with pyrrhotite (Class I), ranging from 47.1 to 92.4 atomic% Au, is clearly higher than that associated with pyrite (Classes IIA, IIB and III). In contrast, classes I, II, and III deposits do not show clear differences in Au content of electrum. In general, pyrrhotite - type gold deposits(I) are characterized by features such as simply massive vein morphology, low values in the Ag/Au total production and ore grade ratios, the absence or rarity of silver - bearing minerals except electrum, and distinctively simple mineralogy. Although the geological and mineralogical features and vein morphology of pyrite - type gold deposits(IIA)are very similar to those of pyrrhotite - type gold deposits (I), Class II A deposits reveal significant differences in the associated iron sulfide (i. e. pyrite) with electrum and Au content of electrum. The Ag/Au total production and ore grade ratios from Class II A deposits are relatively slightly higher than those from Class I deposits. Pyrite - type gold deposits(II B) and argentite - type gold - silver deposits (III) have many common features; complex vein morphology, medium to high values in the Ag/Au total production and ore grade ratios and the associated iron sulfide (i. e. pyrite). In contrast to Class II B deposits, Class III deposits have significantly high Ag/Au total production and ore grade ratios. It indicates distinct difference in the abundance of silver minerals (i. e. native silver and argentite). The fluid inclusion analyses and mineralogical data of electrum tarnish method indicate that the gold mineralization of Classes I and II A deposits was deposited at temperatures between 230° and 370℃, whereas the gold (-silver) mineralization of Classes ITB and ill formed from the temperature range of 150°-290℃. Therefore, Classes I and IT A deposits have been formed at higher temperature condition and/or deeper positions than Classes IIB and III.

忠淸道 一圓의 金ㆍ銀鑛床에 대한 鑛物學的 硏究

Seon Gyu Choi(崔善奎),No Young Park(朴魯榮),Sei Sun Hong(洪世善) 대한자원환경지질학회 1988 자원환경지질 Vol.21 No.3

A large number of gold and/or silver-bearing quartz veins occur in or near Mesozoic granite batholith elongated in a NE-SW direction within the Chungcheong Province. Precambrian schists and gneisses, and Jurassic and Cretaceous granitic rocks serve as hosts for gold and/or silver deposits. On the basis of Ag/Au total production and ore grade ratio, 15 mines may be divided into three major groups: gold-dominant deposits, gold-silver deposits, and silver-dominant deposits. The chemical composition of electrum from skarn deposit (Geodo mine), alaskite-type deposit (Geumjeong mine) and 15 vein deposits was summarized. It was found that the Au content of electrum for vein deposits ranging from 5.2 to 86.5 is lower than that for skarn and alaskite deposits. Among 15 vein deposits, the composition of electrum associated with pyrrhotite is relatively high and has a narrow range of 40.8 to 86.5 atomic % Au, but the Au content of electrum with pyrite is in range of 5.2 to 82.8 atomic %, and is clearly lower than that with pyrrhotite. The grouping of ages for these mines indicates that gold and/or silver mineralizations occurred during two periods in the Mesozoic. Daebo igneous activities are restricted to gold mineralization in the range of 158 to 133 Ma, whereas Bulgugsa igneous activities are related to gold and/or silver mineralization ranging from 108 to 71 Ma. Generally speaking, Jurassic gold-dominant veins have many common characteristics; notably prominent association with pegmatites, simply massive vein morphology, high fineness in the ore concentrates, rarity of silver minerals, and a distinctively simple mineralogy, including sphalerite, galena, chalcopyrite, pyrrhotite and/or pyrite. Although individual deposits exhibit widely differing diversity, Cretaceous gold-silver and silver-dominant veins are characterized by features such as complex vein, low to medium fineness in the ore concentrates and abundance of silver minerals including Ag sulfosalts, Ag sulfides, Ag tellurides and native silver.