• Journal of Korea Foundry Society
• /
• v.41 no.1
• /
• pp.11-15
• /
• 2021

Scrap steel used as a charge material in melting process of cast iron foundry is mostly press scrap. The press scrap usually causes several problems including energy loss, workability, safety, and so on. By charging the shredded scrap instead of the press scrap, it is expected that the above-mentioned problems can be solved. In this study, the power basic units to produce cast iron by using the press and shredded scrap are compared in 3t/h medium-frequency induction melting furnace. Charging the shredded scrap instead of the press scrap was confirmed that the power basic unit is improved by about 15%. The characteristics and restrictions of the usage according to the shape and size of scrap steel were considered.

• Applied Chemistry for Engineering
• /
• v.4 no.4
• /
• pp.785-790
• /
• 1993

Three ester-type chitin derivatives were synthesized by reacting chitin with acetic anhydride, propionic anhydride and n-butyric anhydride to form acetyl chitin(AC), propionyl chitin(PC) and n-butyryl chitin(BC). Methanesulfonic acid was used as a catalyst. FT-IR spectra and solid state CP/MAS $^{13}C-NMR$ spectra of three chitin derivatives showed that the substituents were mainly incorporated in the $C_6$ position of chitin. The ester-type chititn derivatives were dissolved well in formic acid and swollen in aqueous acidic solution.

• The Journal of the Petrological Society of Korea
• /
• v.20 no.3
• /
• pp.161-172
• /
• 2011

Open beaker digestion method is routinely used as the sample preparation technique for trace element determination of rock samples by inductively coupled plasma mass spectrometry, With this method, however, dissolution of Zr and Hf is not always guaranteed especially when the samples contain refractory minerals. In this study, glass bead digestion technique was compared with conventional open beaker digestion technique for the sample preparation of three USGS rock standards such as AGV-2, BHVO-2, and G-3. Thirty trace elements including rare earth elements were analysed by ICP-MS and ICP-AES. There were no clear differences in analytical results for the AGV-2 and BHVO-2 standards between the two techniques, but Zr, Hf, Y, and middle- to heavy- rare earth element concentrations of the G-3 standard prepared by open beaker digestion technique were significantly lower than the recommended values. This can be attributed to the presence of refractory mineral zircon. On the contrary, all the analytical results of the G-3 standard prepared by glass bead digestion technique were in good agreement with the recommended values, indicating complete dissolution of zircon. The analytical results show that the volatile elements such as Pb and Zn were not lost during the preparation of glass bead. Low dilution glass bead digestion technique described here will be very helpful to enhance precision and accuracy of trace element analysis for geological samples containing refractory minerals.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.111.2-111.2
• /
• 2011

야금학적 방법을 통한 태양전지용 실리콘 제조를 위하여 아크로(Arc furnace)에서 제조된 용융 상태의 금속급 실리콘을 슬래그와 직접 반응시켜 불순물을 제거하는 공정에 관한 연구를 수행하였다. 이를 위해 아크로와 고주파 유도용해로(High-frequency induction furnace)를 이용하여 금속급 실리콘을 제조와 정련 특성 실험을 수행하였다. 본 연구에서 금속급 실리콘을 제조하기 위한 장비로 150kW급-DC 아크로와 300kW급-AC 아크로를 사용하였다. 원재료로 규석, 코크스(Cokes), 숯, 그리고 우드칩(Wood chip)을 실험 비율에 맞춰 아크로 내부에 장입하고, 이를 용융환원 방법을 통해 반응을 시켰다. 이때 생산된 금속급 실리콘의 순도는 약 99.2~99.8% 이었으며, 원재료의 순도, 장입 비율 및 아크로 운전 특성에 따라 편차가 있다. 아크로에서 생산된 금속급 실리콘의 경우 인(phosphorus), 붕소(boron)를 다량 함유하고 있고, 이를 제거하기 위하여 50kW급 고주파 유도용해로 장비를 사용하여 슬래그 정련 실험을 수행하였다. 슬래그 정련시 사용한 성분은 SiO2, CaO 그리고 CaF2 이며, 금속급 실리콘과 슬래그의 질량비 및 반응 시간에 따른 실리콘 불순물 특성을 평가하였다. 실험결과 인과 붕소는 각각 1 ppm 이하, 5 ppm 이하 였으며, 칼슘을 제외한 대부분의 금속 불순물의 경우 0.1~0.2% 임을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.3
• /
• pp.800-806
• /
• 2008

The strain HK-12 was enriched and isolated from naturally fermented soybean for the production of fibrinolytic enzyme and the proteome of this enzyme induced during the incubation period was analyzed. The activity of fibrinolytic enzyme derived from supernatants of the HK-12 culture was performed by fibrin plate method for solid fibrinolytic activity. As the result, the fibrinolytic activity of HK-12 grown on the nutrient agar media was about 2.3 times greater than that of plasmin used as standard. The purified enzyme was prepared by a series of purification process including ammonium sulfate precipitation, DEAE-cellulose, Sephadex chromatography. The molecular weight of the enzyme was determined to approximately 23kDa with SDS-PAGE. In order to examine which strain HK-12 proteins increased or decreased during the incubation period, 2-DE analysis was performed. Protein spot #1 significantly expressed on the 2-DE gel of bacteria cultivated for 36-hrs was analysed. As the result of protein sequence analysis using MALDI-TOF MS, one protein was identified as serine protein kinase (PrkA).

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.187.2-187.2
• /
• 2011

태양광산업의 value chain중 up-stream쪽인 고순도 실리콘산업은 셀, 모듈, 시스템 쪽에 비하여 영업 이익률이나 부가가치 측면에서 매우 높은 성장성을 현재 보여주고 있으며 최근 원자력산업의 안전성 문제가 대두됨으로 인하여 태양광수요가 전 세계적으로 증대되는 경향을 나타내어 태양광용 실리콘의 수요가 확대됨과 아울러 spot시장에서의 가격 또한 상승하고 있다. 이런 관점에서 잉곳 및 웨이퍼 가공 중에 발생하는 고순도 실리콘 폐기물의 재활용 이 다시 주목받고 있다. 태양전지 웨이퍼(wafer)용 소재는 6N급 이상의 결정질 실리콘 잉곳(ingot)이 주를 이루며, 고효율의 셀을 제조하기 위해서 단결정 실리콘 잉곳이 많이 사용된다. 실리콘 단결정을 육성하는 방법에는 Floating zone 법, Czochralski 법, Bridgeman 법, CVD 등 매우 다양하다. 이 중 Czochralski 법은 전체 생산량의 대부분을 차지하고 있는 방법으로, 용융액에서 결정을 인상하여 ingot을 제작하는 방법이다. 그러나 대량의 전기에너지를 소비하여 제작되는 고순도의 실리콘 단결정 잉곳은 후 가공공정에서 그 절반 이상이 분말(powder) 및 슬러지(sludge)로 폐기되므로, 자원의 재활용 및 환경오염 측면에서 주요과제가 되고 있다. Czochralski 법으로 제작된 ingot의 경우 그 표면이 매끄럽지 못하여, 웨이퍼 단위의 가공 시 형태가 진원이 될 수 있도록 표면을 미리 연마(grinding)하는데, 이때에도 미세 분말이 다량 발생하게 된다. 본 연구에서는 이러한 고순도 단결정 실리콘 ingot의 연마 가공공정에서 발생한 미세 분말을 용해하여 보았다. 진공 챔버(chamber) 내부에 유도가열 코일과 냉도가니로 구성된 장비를 통해 전자기유도가열을 이용하여 실리콘 분말 폐기물을 용해하고, 그 시편을 ICP-MS 및 비저항 측정을 통해 분말 의 특성을 조사하여 재활용 가능성을 검토해 보았다.

• Journal of the Korean Chemical Society
• /
• v.38 no.8
• /
• pp.576-584
• /
• 1994

The method described offers rapid and efficient sample preparation using on-line microwave digestion of metal oxides in water sample with direct elemental detection by ICP-AES. The open tubing digestion system(OTD) and the restraint tubing digestion system(RTD) for flow injection(FI) were designed and tested to find the optimum conditions. Comparison of OTD and RTD indicated that RTD was 3 times faster on the digestion time, and 10 times higher on sample mass. Finally, the results of RTD agree well with those by conventional microwave open vessel in all cases and show good precision; Fe and Cu show good with about 5% of RSD, while Zn and Co more or less than 10% RSD.

• Journal of Korea Foundry Society
• /
• v.8 no.spc2
• /
• pp.382-392
• /
• 1988

• Journal of Korea Foundry Society
• /
• v.10 no.6
• /
• pp.485-494
• /
• 1990

• JUMULGISUL / FOUNDRY TECHNOLOGY
• /
• v.3 no.2
• /
• pp.30-44
• /
• 1979