• Resources Recycling
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• v.15 no.5 s.73
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• pp.11-16
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• 2006

A novel microwave-induced pyrolysis was used for the recovery of valuable products from waste polystyrene in motor oil. Quartz tube was introduced as microwave reactor and silicon carbide was used as the microwave absorbent. In the experiments, different pyrolysis conditions were applied, such as time range from 30 minutes to 1 hour and microwave input power range from 180 to 250W. The distillate products from pyrolysis were analyzed with GC/MS. Styrene, 1-methyl styrene, toluene, ethyl benzene were the four main products. Styrene recovery rate from polystyrene was around 50%. Temperature for the complete pyrolysis using microwave was around $300^{\circ}C$ which is much lower than that of conventional thermal pyrolysis.

• Resources Recycling
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• v.6 no.1
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• pp.5-10
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• 1997

The aluminum was recovered from the middle size (Q1.0-12.0 mm) aluminum drosses using NaCl and KC1 mixuture as a basic salt flux. The maximum aluminum recovery was about 76.9% when 40% basic salt flux was added to aluminum dross at 850$^{\circ}$C for two hours. Also, aluminum remvery increased with increasing fluoride (1%-5%) addition to basic salt flux. But, there was no considerable effect due ta the increasing of viscosity when the fluorides were added over 5%, respectively. E s p d y , the most aluminum recovery was about 83.5% when 5% cryolite was added to 40% basic salt flux.

• KSBB Journal
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• v.5 no.1
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• pp.59-67
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• 1990

Enzymatic hydrolysis of insoluble cellulose was performed in a bubble column with tangential flow ulrafiltration membrane unit. The reactor was operated in a batch mode as well as semi-continuous and continuous with continuous removal of products through the tangential flow ultrafiltration membrane. The optimum superficial gas velocity was 1-3cm / sec so as to avoid bubble coalescence and enzyme denaturation. In continuous and selni-cotinuous process, the conversion was gradually increased but the total reduced sugar concentration was drcastically dereased with the dilution rate. It was concluded that the bubble column attaching tangential flow ultrafiltration membrane unit was effective on continuous hydrolysis of cellulose and recovery of enzyme.

• Digital Contents
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• no.7 s.50
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• pp.42-47
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• 1997

국내에서 STN을 이용하려면 산업기술정보원에서 ID와 패스워드를 부여받아야 하고 이용요금은 각 데이터베이스마다 검색어 사용 회수와 접속시간 및 출력건수에 따라 다른데 CA같은 경우에는 시간당 약 150$정도가 된다. 가입비는 25$이다.

• Resources Recycling
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• v.29 no.5
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• pp.48-54
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• 2020

Sulphuric acid (H₂SO₄) leaching and hydrolysis were experimented for the recovery of titanum dioxide (TiO₂) from the water-leached residue followed by soda-roasting spent SCR catalysts. Sulphuric acid leaching of Ti was carried out with leachate concentration (4~8 M) and the others were fixed (temp.: 70 ℃, leaching time: 3 hrs, slurry density: 100 g/L, stirring speed: 500 rpm). For recovering of Ti from the leaching solution, hydrolysis precipitation was conducted at 100 ℃ for 2 hours in various mixing ratio (leached solution:distilled water) of 1:9 to 5:5. The maximum leachability was reached to 95.2 % in 6 M H₂SO₄ leachate. on the other hand, the leachability of Si decreased dramatically 91.7 to 3.0 % with an increase of H₂SO₄ concentration. Hydrolysis precipitation of Ti was proceeded with leaching solution of 8 M H₂SO₄ with the lowest content of Si. The yield of precipitation increased proportionally with a dilution ratio of leaching solution. Moreover, it increased generally by adding 0.2 g TiO₂ as a precipitation seed to the diluted leaching solution. Ultimately, 99.8 % of TiO₂ can be recovered with the purity of 99.46 % from the 1:9 diluted solution.

• Resources Recycling
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• v.13 no.1
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• pp.14-21
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• 2004

Spent catalysts containing platinum were generated in petroleum refinery and other chemical industries. The reclamation of platinum metals from such wastes has long been attempted in view of their rare, expensive and indispensable nature. In this study, the recovery of platinum from petroleum catalysts was attempted by a method consisting mainly of dissolving alumina carrier with sulfuric acid thereby concentrating insoluble platinum. Also, platinum dissolved partially in sulfuric acid was recovered by a cementation method using aluminum metal as a reductive agent. The effect of temperature, time, concentration of sulfuric acid, and pulp density on the dissolution of carrier was investigated. When the carrier of platinum catalyst was $\Upsilon-Al_2$O$_3$ about 95% alumina was dissolved in 6.0 M sulfuric acid at $100^{\circ}C$ for 2 hours. When the carrier was the mixture of $\Upsilon-Al_2$$O_3$ and $\alpha$-$Al_2$$O_3$ about 92% was dissolved after 4 hours. As a result, more than 99% of platinum could be recovered by this method and aluminum sulfate was also obtained as byproduct.

• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.332-337
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• 2009

Most propionic acid is added to food (especially breads) as preservatives and its form is sodium or calcium salt. Most countries admitted propionic acid as food preservatives but a tolerance limit is somewhat different according to countries. Recoveries of the official method for propionates reported as 50.0~60.0%. Accordingly new rapid determination method for propionates was developed using formic acid added sodium chloride (5 g) and ether (formic acid : ether = 1 : 2) as the extraction solvent to improve the official method with the complex processes. Propionate was dissolved from the samples with formic acid omitting steam distillation and ion exchange procedure. Then propionate in formic acid was extracted with ether and sodium chloride again. A $1\;{\mu}l$ aliquot of the filtrate of ether was analyzed by gas chromatograph. Recoveries from sample A and B fortified with propionic acid sodium salt were 85.0 % and 90.0 %, respectively.

• Resources Recycling
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• v.7 no.2
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• pp.39-45
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• 1998

We smelted thc pellets made by mixing the distilled carbon from wlISte Lires, LD converter dust and slag with reduction process in the revcrberatory furnace. Thc obtained results are as follows 1) The removal mte of zinc appears above 97% after T reducing the pellets at $1300^{\circ}C$ for Ihr and the zinc content in the residue are 0.1~D.2%. 2) Under the mixing condition of 500 g LD dust. 150-200 g LD slag and 30-50 g distilled carbon of waste lires the removal raho of zinc shows above 95%, while t the 50-60% Fe remains in the residue. 3) After smelting at $1350^{\circ}C$ for 3hrs, the recovery ratio of pig iron reduced from lhe p pellets containing 15-20% LD slag and 4.1-7.2% distilled carbon of waste tires appears in the range of 89.3-92%. 4) Tbe c chemical composition of the recovered pig iron is 1.7%C, O.05%P, 0.05%S and balance Fe. 5) Tbe recovered dust from the d dust collcctor alter finishing the reduction rcaction appears as a crude zinc oxide conLaining 60% zinc.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06b
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• pp.289-293
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• 2007

낸드 플래시 메모리는 특성상 덮어 쓰기가 불가능하기 때문에 유효하지 않는 데이터가 저장된 더티(Dirty) 상태의 페이지를 삭제 연산을 통해 클린(Clean) 상태로 만든 후 데이터를 써야 한다. 더티 페이지가 낸드 플래시 메모리에 많이 존재하면 파일을 쓸 때 많은 블록을 삭제해야 하기 때문에 쓰기 지연 시간이 길어지는 문제가 발생한다. 따라서 본 논문에서는 일정한 쓰기 지연 시간을 보장하는 새로운 페이지 할당 및 회수 기법을 제안한다. 파일이 삭제될 때 더티 상태인 페이지를 삭제함으로써 클린 상태로 변경하여 낸드 플래시 메모리에 쓰기 지연 시간을 길게 만드는 더티 페이지가 없는 상태로 유지한다. 또한 삭제 연산은 블록 단위로 수행되므로 삭제할 블록의 유효한 페이지를 다른 블록으로 복사해야 하기 때문에, 페이지를 할당할 때 한 블록에 가급적 적은 개수의 파일을 저장하는 알고리즘을 제시한다.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.293-293
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• 2004

본 실험은 도축전 암소에 성선자극호르몬(Gonadon, 동방(주) : 3 ㎖ 목근육 주사, Gonadorelin 100 ㎍/㎖)을 처리하여 인위적으로 새로운 발정주기를 유도하여 난자 회수율 및 수정란 생산성을 향상시키고자 실시하였다. ① 실험대조군으로 85두(T1), 호르몬처리 37두를 대상으로 처리시간(T2 ; 72hrs, T3 ; 96 hrs, T4 ; 120. T5 ; 148 hrs.)에 따라 도축 후 난소로부터 혈통수정란 생산을 위해 개체별로 난자 회수량을 확인하였다. 회수된 난자를 이용하여 체외성숙 및 체외수정을 실시하였고, 이들 난자의 발육상태, 난발달 및 동결가능 수정란수를 각각 확인하였다. (중략)