• 대한치과보철학회지
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• 제14권1호
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• pp.31-34
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• 1976

The author studied the effects of some dental gold alloys and dental nonprecious metals on muscle. The metal specimens were cast in the size of $1.0mm.{\times}5.0mm.{\times}3.0mm.$ and implanted in the gluteus maximus musculus of the two dogs. The subjects were sacrificed at 3 weeks and 5 weeks respectively after implantation. The tissue was examined his to-pathologically. The findings were as follows. 1. The more the alloy contains gold, the less the tissue response to the alloy and the less the connective tissue layer around the specimens. 2. The recovery of connective tissue layer in gold specimens was markedly observed. 3. There were very thick connective layers around nonprecious specimens.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.801-806
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• 2001

A study has been carried out on the separation of gold, iridium, palladium, rhodium, ruthenium and platinum in chromite samples and their quantitative determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). The dissolution condition of the minerals by fusion with sodium peroxide was optimized and chromatographic elution behaviour of the rare metals was investigated by anion exchange chromatography. Spectral interference of chromium, a matrix of the minerals, was investigated on determination of gold. Chromium interfered on determination of gold at the concentration of 500 mg/L and higher. Gold plus trace amounts of iridium, palladium, rhodium and ruthenium, which must be preconcentrated before ICP-AES was separated by anion exchange chromatography after reducing Cr(Ⅵ) to Cr(III) by H2O2. AuCl4- retained on the resin column was selectively eluted with acetone- HNO3-H2O as an eluent. In addition, iridium, palladium, rhodium and ruthenium remaining on the resin column were eluted as a group with concentrated HCl. However, platinum was eluted with concentrated HNO3. The recovery yield of gold with acetone-HNO3-H2O was 100.7 ${\pm}2.0%$, and the yields of palladium and platinum with concentrated HCl and HNO3 were 96.1 ${\pm}1.8%$ and 96.6 ${\pm}1.3%$, respectively. The contents of gold and platinum in a Mongolian chromite sample were 32.6 ${\pm}$ 2.2 ${\mu}g$/g and 1.6 $\pm$ 0.14 ${\mu}g$/g, respectively. Palladium was not detected.

• 한국광물학회지
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• 제32권3호
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• pp.185-200
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• 2019

본 연구목적은 비-가시성 금 정광(Au = 1,840.00 g/t)으로부터 금을 단체분리 시키기 위하여 마이크로웨이브-질산침출 실험을 수행하였다. 이를 위해 질산농도 효과, 마이크로웨이브 침출시간 효과 그리고 시료 첨가량 효과에 대하여 마이크로웨이브-질산침출 실험을 수행하였다. 본 연구의 실험조건에서는 금이 전혀 침출되지 않은 것으로 조사되었다. 불용성-잔류물의 무게는 질산 농도, 마이크로웨이브 침출시간 그리고 시료 첨가량이 증가할수록 감소하는 경향으로 나타났다. 불용성-잔류물에 대하여 XRD 분석한 결과 석고와 anglesite가 나타나는데 이는 정광에 포함된 방해석과 방연석이 질산용액과 반응하여 생성된 것으로 사료된다. 불용성-잔류물에 대하여 납-시금법을 수행한 결과 정광보다 금함량이 최소 1.3배(Au = 2,464.70 g/t)에서 최대 28.8배(52,952.80 g/t)로 높게 나타났다. 그러나 납-시금법에서 회수된 금 함량은 gold nugget effect가 매우 심하게 나타났다. 향후, 마이크로웨이브-질산침출 실험에서 정광의 시료채취 방법을 개선하고, 더 작은 기공 크기의 여과지를 사용하여 침출용액을 여과하고 납-시금법에서 여과지를 태워서 시료로 투입하는 방법을 수행한다면 gold nugget effect를 감소시킬 수 있을 것으로 기대된다.

• Progress in Superconductivity
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• 제9권1호
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• pp.119-125
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• 2007

We investigated recovery in $Au/YBa_2Cu_3O_7$ (YBCO) thin film meander lines on sapphire substrates. The meander lines were fabricated by patterning YBCO films coated with gold layers. The lines were subjected to simulated AC fault current and then small current was applied for recovery measurements. The samples were immersed in liquid nitrogen during the experiment. After the fault, the resistance decreased linearly, first slowly and then fast to zero. The initial slow decrease was due to the decrease of the meander line temperature, whereas the fast decrease was originated from the transition from the normal state to the superconducting state. The recovery speed depended on the size of samples, and was faster in the smaller samples during the whole period of recovery. The experimental results were analyzed quantitatively with the concept of heat transfer within the sample and to the surrounding liquid nitrogen. A heat balance equation was solved for the initial phase of recovery, and an expression for the time dependence of resistance was obtained. The result agreed with data well.

• 한국정밀공학회지
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• 제17권8호
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• pp.26-40
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• 2000

• 한국임상수의학회지
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• 제30권2호
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• pp.100-106
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• 2013

A clinical trial was performed to assess clinical efficacy and/or reduction in relapses by gold-bead implantation into acupuncture points in dogs with canine chronic recurrent otitis externa (CCROE). Forty dog-patients randomly divided into two groups were diagnosed as suffering CCROE, having intact tympanic membranes and a history of recurrences. Treatments were: control group (CG), treated with commercially available antimicrobial otic droplets, dosed twice daily for 7 days; and experimental group (GBI- gold bead implants), treated as for CG plus the insertion of 13 gold-bead implants under light anesthesia. Overall per cent assessment of composite clinical progression and progression of individual clinical signs were recorded. Bilateral chronic external otitis was diagnosed in 60% of the cases and left or right otitis in 20% of the cases each. Logistic model for repeated measures analysis showed that GBI induced a better clinical recovery as far as lesion score of some clinical signs is concerned. The overall percent cures of each group showed statistically significant difference. A McNemar analysis revealed that higher number of relapses was observed in CG patients as compared to the GBI (P < 0.05). In particular during these days, lesion on the pinna showed in odd ratios analysis a 7:1 ratio (recurrence CG:GBI) and ear wax/pus (4:1) from D42 to D365. It is concluded that gold-bead implantation into acupuncture points improves resolution of some clinical signs and greatly reduce relapses in CCROE affected dogs after 1 year follow-up (98.75%).

• 자원리싸이클링
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• 제22권4호
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• pp.33-37
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• 2013

열분해법(thermal decomposition method)을 이용하여 금 정광으로부터 비소를 제거하기 위해 $700^{\circ}C$에서 반응시간을 변화시키면서 실험을 진행하였다. 또한, 금 정광으로부터 휘발된 비소는 bag-filter를 이용하여 회수하였다. 정광중의 비소 함량은 $700^{\circ}C$에서 1시간 소성한 결과 12.62 wt.%에서 1.40 wt.%로 급격히 감소하였으며, 2시간 이후부터는 1 wt.%이하로 감소하여 대략 95%의 비소 제거율을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.117-120
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• 1988

A new current source inverter (CSl) with dc-side commutation and load-side energy recovery circuit is proposed with analysis and explanation of the circuit operation. Proposed inverter overcomes the most drawbacks of the conventional CSI's - high device voltage stress, low operating frequency range, large commutation capacitance, etc. - by employing simultaneous recovery and commutation concept. The new CSI employs only one commutation capacitor and it can be built with considerably low cost. The commutation energies are temporarily stored into a large dc capacitor and recovered to the load side, thus the device voltage stress is low and the efficiency is high in the proposed inverter. Computer simulation results are given at the steady state, and a guideline determining the commutation circuit is given.

• 한국표면공학회지
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• 제49권6호
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• pp.477-485
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• 2016

As expensive and valuable metals being used in electronic and semiconducting industries are abandoned as industrial wastes after use of them, it is required to recover them from e-wasted electronics parts. Gold which is used for printed circuit boards or electronic equipments, accessories, etc., is one of e-Wasted materials and recently indium, gallium, zirconium, cobalt, molybdenum and lithium are bacome valuable metals to be recovered from the e-wastes. Since the amount of precious metals is now being faced with scarcity, lean too much on area and instability of supply, and industrial demands are rapidly increasing every year, it becomes more important to recover the valuable metals from the industrial wastes. In this review, we introduced technologies and research trend of the recovery processes of valuable metals from the e-wastes in high-tech devices over the world.

• 자원리싸이클링
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• 제24권4호
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• pp.61-66
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• 2015

전세계적으로 시안화법은 일차 광물 혹은 정광으로부터 금을 회수하기 위해 널리 사용되어 왔다. 그러나 이 공정에서 발생하는 다량의 유독한 잔사 및 시안 함유 폐액은 주변 환경 및 생태계에 심각한 문제를 야기할 수 있어 그 사용에 대해 문제가 제기되어 왔으므로 시안화법 이용 시 반드시 시안 함유 폐액의 적절한 처리가 필요하다. 본 연구에서는 금광으로부터 금을 회수하기 위한 습식제련공정인 시안화법과 연계하여 시안 처리 공정을 설계하기 위한 기초연구로서 금 제련에 사용되는 시안화합물의 사용, 규제 및 처리 기술의 국내외 현황을 분석하였다. 또한 무배출 금 회수 및 처리 공정을 설계하기 위한 생물학적 공정에 대하여 소개하였다.