• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.134-139
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• 2018

One of the most common problems with pedicle screw system is pullout of the screw. This study was performed to evaluate the pullout strength and driving torque of newly designed pedicle screws. The design of three type screws were standard pedicle screw, which had single lead threaded and single pitched design (Type A), single pitched and dual lead threaded pedicle screw (Type B), dual pitched and dual lead threaded pedicle screw (Type C), respectively. The tests were performed in accordance with the ASTM standards using polyurethane (PU) foam blocks. There was no significant difference in pullout strength among three types of screw. Type B and Type C exhibited higher insertion torque and removal torque than Type A, respectively (p<0.05). Pedicle screws newly developed with dual pitched and dual lead threaded design showed higher driving torque without decrease in pullout strength compared to the standard pedicle screw and could be inserted more rapidly with the same number of revolutions.

• Journal of the Korean Society of Food Culture
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• v.18 no.6
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• pp.544-550
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• 2003

This study was designed to investigate the effects of Korean 1% Shanshuyu extract in Pb administered rats. Forty male Sprague-Dawley rats weighed 100 l0g were used for this experiment and divided into following 4 groups; Con(control group), Shan(1% Shanshuyu extract), Pb(1,000ppm alone lead administered group), Pb-Shan(1,000ppm alone lead administered group with 1% Shanshuyu extract group). Food intake weight and FER(Food efficiency ratio) were remarkably decreased in lead added group. Tissue weight of liver, lung, stomach, heart, kidney and spleen of lead exposed rats were reduced by 1% Shanshuyu extract group. The lead content in the rats tissue of lead alone administered group was lower than in the rats tissue of lead administered group with 1% Shanshuyu extract group. AST(Asparatate transferase) and ALT(Alanine transferase) were increased in lead-administered group and lower in the 1% Shanshuyu extract group. These results suggested that 1% Shanshuyu extract may have some protective effects from of tissue demage induce with Lead.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.675-680
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• 2004

This study was conducted to remove organics and nutrients using 2 stage intermittent aeration reactor. First reactor, using suspended microbial growth in intermittent aeration instead of anaerobic reactor in the typical BNR process, used minimum carbon source to release P, and it was possible to reduce ammonia loading going to second reactor. In the second reactor, using moving media intermittent aeration, it was effective to reduce nitrate in non-aeration time by attached microorganisms having long retention time. In aeration time, nitrification and P uptake were taken place simultaneously. From the experiment, two major results were as follows. First, the removal of organics was more than 90%, and optimum aeration/non-aeration time ratio for organic removal was corresponded with aeration/non-aeration time ratio for nitrogen removal. Second, in the first reactor, optimum aeration/non-aeration time ratio was 15/75 (min.) because it was necessary to maintain 75 min. of non-aeration time to suppress of impediment of return nitrate and to lead release of phosphate. In the second reactor, optimum aeration/non-aeration time ratio was 45/90 (min.).

• Journal of Environmental Science International
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• v.21 no.11
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• pp.1371-1377
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• 2012

The simulated dyes solution containing Basic Red 46(BR 46), Yellow 21(Y 21), and Maxilon Blue 30(MB 30) were electrochemically oxidized using carbon fiber as an anode. The electrolyses were performed in a electrolytic flow cell constructed by Vycor glass tube. The carbon fiber was positioned in the inside of Vycor glass tube and platinum wire coiled around outside of tube as a cathode. Several operating variables, such as current, time, pH and flow rate of solution were studied. Increasing current density would lead to a corresponding increase in the dye removal efficiency 99.2 % at a 200 mA. The electrolyses time could also improve and removal efficiency was about 99 % after 1.5 hours of electrolyses. The removal efficiency was increased with the increase of flow rate of solution and optimum flow rate was 5 mL/min. THe pHs of solution affect the removal efficiency. The removal efficiency was decreased with the increase of pH of solution and optimum pH was 5.05 (0.1 M $KNO_3$).

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.316-321
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• 2013

Electrocoagulation (EC) technique is applied for the treatment of wastewater containing heavy metals ions such as nickle (Ni), lead (Pb) and cadmium (Cd) by using sacrificial anodes corrode to release active coagulant flocs usually aluminium or iron cations into the solution. During electrolytic reactions hydrogen gas evolve at the cathode. All the experiments were carried out in Batch mode. The tank was filled with synthetic wastewater containing heavy metals and efficiency of electro-coagulation in combination with aluminum and iron electrodes were investigated for removal of such metals. Several parameters, such as contact time, pH, electro-coagulant concentration, and current density were optimized to achieve maximum removal efficiency (%). The concentrations of heavy metals were determined by using Atomic Absorption Spectroscopy (AAS). It is found that the electro-coagulation process has potential to be utilized for the cost-effective removal of heavy metals from wastewater specially using iron electrodes in terms of high removal efficiencies and operating cost.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.3
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• pp.289-297
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• 2004

Emissions of volatile organic compounds and odors from various industrial processes not only pollute surrounding life environments, but also lead to the deterioration of the working environments, causing various industrial health and business problems. These pollutants are usually stimulating, irritating, malodorous and sometimes carcinogenic, Which should be reduced in the pollutants formation, stage, but the practical processes do not allow This paper describes the major sources of VOC and odors, and their sampling/analysis methods. Furthermore, various removal technologies for these pollutants are suggested, which particularly include the characteristics of the catalytic and scrubber/carbon filter combined process, and even process design technologies.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.352-355
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• 2003

27 passive systems in 21 mines constructed by The Coal Industry Promotion Board since 1996 were investigated to evaluate the treatment efficiency of systems and find problems in each system, which will eventually lead to the improvement or suggesting the alternative method of the passive treatment system. Problems in operation include overflow, leakage, inefficiency and unusablness. The efficiency of systems which has been evaluated by metal(Fe) removal rate and/or by acidity removal rate do not reflect the poor removal rate of S $O_4$$^{2-}$. Especially high concentration of S $O_4$$^{2-}$ and high COD in the beginning of the operation would decrease the bacteria activity due to the lack of the nutrition. To solve the problem of overflow the upflow-type SAPS is being considered.

• Biotechnology and Bioprocess Engineering:BBE
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• v.2 no.2
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• pp.132-135
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• 1997

We prepared capsules containing Saccharomyces cerevisiae and Zoogloea ramigera cells for the removal of lead(II) and cadmium ions. Microbial cells were encapsulated and cultured in the growth medium. The S.cerevisiae cells grown in the capule did not leak through the capsule membrane. The dried cell density reached to 250 g/l on the basis of the inner volume of the 2.0 mm diameter capsule after 36 hour cultivation. The dry whole cell expolymer density of encapsulated Z.ramigera reached to 200 g/L. The capsule was crosslinked with triethylene tetramine and glutaric dialdehyde solutions. The cadmium uptake of encapsulated whole cell expolymer of Z.ramigera was 55mg Cd/g biosorbent. The adsorption line followed well Langmuir isotherm. The lead uptake of the encapsulated S. cerevisiae was about 30 mg Pb/g biomass. The optimum pH of the lead uptake using encapsulated S. cerevisiae was found to be 6. Freundlich model showed a little better fit to the adsorption data than Langmuir model 95 percent of the lead adsorbed on the encapsulated biosorbents was desorbed by the 1 M HCl solution. The capsule was reused 50 batches without loosing the metal uptake capacity. And the mechanical strength of the crosslinked capsule was retained after 50 trials.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.673-678
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• 2011

With an increased production of Printed Circuit Boards (PCBs) in electronic equipment, the consumption of solder alloys is growing globally. Recently, increasing importance of recycling solder scrap has been recognized. Generally, solder scrap contains many impurities such as plastics and other metals. Hazardous components must be eliminated for recycling solder scrap. The present work studied pretreatment for reuse of solder scrap alloys. An experiment was conducted to enhance the cleanliness of solder scrap melt and eliminate impurities, especially lead. Physical separation with sieving and magnetic force was made along with pyrometallurgical methods. A small decrease in lead concentration was found by high temperature treatment of solder scrap melt. The impurities were removed by filtration of the solder scrap melt, which resulted in improvement of the melt cleanliness. A very low concentration of lead was achieved by a zone melting treatment with repeated passage. This study reports on a pretreatment process for the reuse of solder scrap that is lead free.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1747-1756
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• 2000

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0.8 SUPRA) were used as packing material in a fixed-bed column. When 1 g crab shell was added in the column packed with 10 g activated carbon. breakthrough to influent 10 mg Pb/L occurred at 1520 bed volumes. as compared to 380 bed volumes for 10 g activated carbon only. Addition of crab shell particles into activated carbon column resulted in increased uptake of lead. The dramatic improvement might be attributed to an increase in $co_3{^{2-}}$ and $OH^-$ available for the binding of lead. From the result of analyses, the major mechanism of lead removal was based on dissolution of $CaCO_3$ in the crab shell followed by precipitation of $Pb_3(CO_3)_2(OH)_{2(s)}$ on the surface of activated carbon. The lead uptake increased two fold as the influent lead concentration was increased from 10 to 50 mg/L. However, it decreased by 40% as the influent pH was lowered from 5.0 to 3.0.