• The Korean Journal of Mycology
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• v.1 no.1
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• pp.35-43
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• 1973

저자(著者)는 우리나라산(産) 균심류의 정체(正體)를 구명(究明)하고자 1946년(年)부터 금일(今日)에 이르는 동안 서울시내(市內), 광릉(光陵), 수원(水原), 양양(襄陽), 속초(束草), 설악산(雪嶽山), 목포(木浦), 나주(羅州), 울산반도등지(蔚山半島等地)의 산야(山野) 인가(人家) 노변(路邊)에서 야생균심(野生)을 채집정리(採集整理)하여 기(旣)히 조사발표(調査發表)된 종(種)을 종합(綜合)하여 2문(門), 2강(綱), 3목(目), 12아목(亞目), 22과(科)7아과(亞料), 274종(種)을 보고(報告)하는 바이다. 저자(著者)가 금일(今日)까지 미기록종(未記錄種)으로 사정(査定)한 종(種)은 하기(下記)와 같다. 1. Polysticus flabelliformis (Klotzsch.) Cke. 2. Thelephora palmata (Scopoli) Fr. 3. Russula nigricans (Bull.) Fr. 4. Omphalia sp. 5. Peziza repanda Pers. 6. Wynnea gigantea Berk. et Curt. 7. Helvella crispa (Scop.) Fr. 8. Helvella epipploides Imai 9. Cordyceps militaris (L.) Link

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.53-53
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• 2000

반도체 산업에서 유기물질의 응용에 많은 관심을 나타내고있으며, 그 응용의 예로는 발광 다이오드(light emitting diode)와 박막트랜지스터(thinfilm transistor)가 주를 이루고 있다. 이러한 유기 물질을 이용하면 소자의 제작 공정의 단순화와 제작 가격을 낮출 수 있는 이점을 기대할 수 있다. 본 연구에서는 유리 기판 위에 pentcence 다이오드를 제작하였다. 유리 기판 위에 silicon dioxide를 PECVD으로 성막하였다. 전극으로는 Ohmic contact를 이루기 위해 금(Au)을 사용하였으며 schottky contact을 이루기 위해서 알루미늄(Al), 인듐(In), 크롬(Cr), 은(Ag), 금(Au)을 각각 사용하였다. 소자의 활성 층으로는 pentcene을 가장 단순한 열 증착법으로 성막하였고, 진공도는 10-8Torr를 유지하였으며 성막 속도는 0.3 $\AA$/sec로 성막하였다. 제작된 소자들은 $\alpha$-step, I-V, C-V, AFM, IR등을 이용하여 측정, 분석하였다.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.98-102
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• 2010

Magnolia kobus leaf extract was used for the synthesis of bimetallic Au core-Ag shell nanoparticles. Gold seeds and silver shells were formed by first treating aqueous solution of $HAuCl_4$ and then $AgNO_3$ with the plant leaf extract as reducing agent. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of bimetallic nanoparticles. The synthesized bimetallic nanoparticles were characterized with transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy(XPS). TEM images showed that the bimetallic nanoparticles are a mixture of plate(triangles, pentagons, and hexagons) and spherical structures. The atomic Ag contents of the bimetallic Au/Ag nanoparticles determined from EDS and XPS analysis were 34 and 65 wt%, respectively, suggesting the formation of bimetallic Au core-Ag shell nanostructure. This core-shell type nanostructure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

• 전기의세계
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• v.46 no.1
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• pp.28-32
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• 1997

진공관(전자관)은 무선통신, 레디오 방송, 레이다, 전자계산기, VHF 텔레비젼 방송, 마이크로웨이브중계, 컬러(color) 텔레비젼 방송, 전자계측, 전자진단, 위성통신, UHF 텔레비젼 방송, 위성방송 등 통신 및 전자기술의 발전에 상응하여 다양하게 발전 해 왔다. 이러하던 중, 1948년데 이르러 트랜지스터가 미국에서 발명되어 이 고체 디바이스가 대두하면서 이것이 발전을 거듭하는 동안 진공관(전자관)은 이 고체 디바이스와 경합을 하고 있으며 결과적으로 진공관(전자관)은 응용면에서 특히 통신, 방송에 관련되는 진공관들의 상당부분이 고체 디바이스에 자리를 넘겨주고, 시장도 극히 협소해졌다. 나아가 국제적인 동업자와의 경합, 진공관(전자관)동업자끼리의 경합이 있는 등, 진공관(전자관)의 환경은 점점 엄중해진 것이 현재의 상황이다. 그렇다고는 하지만, 여전히 진공관(전자관)이어야만 하는 영역이 있으며, 개발의 필요를 강하게 받고 있다. 이의 개발에 대한 국제협력의 길도 열려 있으며, 금후에도 기술의 계속과 발전을 위해서의 노력이 계속되어, 정력적인 개발이 진행되리라고 보아진다. 금후의 전개를 기대하고 싶다.

• Journal of the Mineralogical Society of Korea
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• v.29 no.3
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• pp.113-122
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• 2016

This study aims to improve the recovery of gold and silver by removing hematite from gold ore of an oxidation zone with ammonia solution. Quartz, hematite and muscovite were present in the oxidation zone, while hematite was hydrogenous. As a result of performing an ammonia leaching test on variables, it is found that the maximum Fe leaching parameter was $-45{\mu}m$ particle size, 1.0 M sulfuric acid concentration, 5.0 g/l ammonium sulfate concentration and 2.0 M hydrogen peroxide concentration. It is also confirmed that goethite was precipitated and formed from that ammonia elution. As the amount of Fe-removal was increased in a solid-residue, the recovery of Au and Ag were increased, too.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.21-28
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• 2013

In order to optimize gold leaching from refractory sulfide concentrate, a HCl-NaClO-$FeCl_3$ solution with varying attributes was applied to the roasted concentrate from Uil mine. The gold from Uil mine occurs in the form of invisible gold that is difficult to leach. The results of the gold leaching experiments showed that the best gold leaching parameters were $550^{\circ}C$ of roasting temperature, 2.0 M of concentration, 1.0% of pulp density, and $70^{\circ}C$ of leaching temperature. It is confirmed that the HCl-NaClO-$FeCl_3$ solution was an environmentally friendly method to leach gold and silver from the refractory sulfide concentrate as an alternative lixiviant to cyanide.

• Economic and Environmental Geology
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• v.22 no.3
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• pp.221-235
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• 1989

Gold-silver mineralization of the Goryeong-Waegwan area was deposited in three stages of quartz and calcite veins which fill fissures in Cretaceous sedimentary rocks of the Sindong Group. Radiometric dating indicates that mineralization is Late Cretaceous age(98 Ma) likely associated genetically with intrusion of a small biotite granite stock. Fluid inclusion and stable isotope data indicate that Au-Ag ore was deposited at temperatures between $280^{\circ}C$ and $230^{\circ}C$ from fluids with salinities between 1.7 and 8.7 equiv.wt.% NaCl. Evidence of boiling indicates pressures of <100 bars, corresponding to depths of 425 and 1,150m, respectively, assuming lithostatic and hydrostatic loads. Within ore stage I there is an apparent decrease in ${\delta}^{34}S$ values of $H_2S$ with paragenetic time, from +1.4 to -2.5 per mil. This pattern was likely achieved through progressive increases in pH and activity of oxygen accompanying boiling. Measured and calculated hydrogen and oxygen isotope values of ore-forming fluids(${\delta}D$ = -90 to -100 per mil; ${\delta}^{18}O$ = +3.9 to -11.4 per mil) indicate meteoric water dominance, approaching unex-changed meteoric water values. Au-Ag deposition is thought to be the result of cooling and dilution of a boiling fluid through mixing with less evolved meteoric waters.

• Economic and Environmental Geology
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• v.22 no.4
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• pp.303-314
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• 1989

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.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.177-185
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• 2014

Purpose: This study is designed to investigate the various impacts of different types of scaler tips such as cooper alloy base tip and the others on the surface roughness of teeth and implant by the method which is currently in clinical use. Materials and methods: Four different types of disc shaped porcelain, titanium, zirconia, and Type III gold alloy dental materials sized 15 mm diameter, 1.5 mm thickness were used for the experiment. Plastic hand curette (Group PS), cooper alloy new tip (Group IS), and stainless steel tip (Group SS) were used as testing appliances. A total of 64 specimens were used for this study; Four specimens for each material and appliance group. Surface roughness was formed with 15 degree angle in ultrasonic scaler tip and with 45 degree angle in hand curette of instrument tip and the specimen surface with 5 mm long, one horizontal-reciprocating motion per second for 30 seconds by 40 g force. To survey the surface roughness of each specimen, a field emission scanning electron microscope, an atomic force microscope, and a surface profiler were used. (Ra, ${\mu}m$). Results: According to SEM, most increased surface roughness was observed in SS group while IS groups had minimal roughness change. Measurement by atomic force microscope presented that the surface roughness of SS group was significantly greater than those of PS, IS and control groups in the type III gold alloy group (P<.05). IS group showed lesser surface roughness changes compared to SS group in porcelain and gold alloy group (P<.05). According to surface profiler, surface roughness of SS group showed greater than those of PS, IS and control groups and IS group showed lesser than those of SS group in all specimen groups. Type III gold alloy group had large changes on surface roughness than those of porcelain, titanium, zirconia (P<.05). Conclusion: The result of this study showed that newly developed copper alloy scaler tip can cause minimal roughness impacts on the surface of implant and dental materials; therefore this may be a useful alternative for prophylaxis of implant and restored teeth.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.537-549
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• 2007

The characteristics of the mineralization and geology in the northern Mt. Taebaek mining district are found to be similar with those reported from Nevada district where the Carlin-type gold deposit occurs characteristically as repeated metallic ore deposits in space and time. Though two spots of hs and several spots of Sb anomalies were recognized in the Yeongweol area, they have no relationship with any metalliferous mineralization. On the other hand, two spots of As anomaly in the Jeongseon area have shown to be related with metalliferous ore deposits (mainly Ag-Au), and they are closely associated with Sb anomaly. Some elements of altered limestones in the study such as Au, Ag, As, Sb, Cu, Pb, Zn, and Mo area are closely associated together, and are more enriched in the Jeongseon area than in the Yeongweol area. In particular, Sb and As which may reflect the occurrence of the Carlin-type gold deposit are highly enriched. However, the base metals such af Zn and Pb are highly variable according to samples. The patterns of the enrichment factor for Sb and As, as well as those for Ag and Au, are very similar with those reported from the Carlin-type gold deposits in Nevada. These similarities in elemental distribution may imply that hydrothermal ore mineralization in the study areas was possibly originated from a fluid with the characteristics of the Carlin-type gold mineralization found in Nevada, China, and Indonesia. However, the pattern of base metals and Mo are different. This may result from different chemistry and/or mineralogy of host rock in the study areas.