• Title/Summary/Keyword: Contamination process

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Recovery of Silicon Wafers from the Waste Solar Cells by H3PO4-NH4HF2-Chelating Agent Mixed Solution (인산-산성불화암모늄-킬레이트제 혼합용액에 의한 폐태양전지로부터 실리콘웨이퍼의 회수)

  • Koo, Su-Jin;Ju, Chang-Sik
    • Korean Chemical Engineering Research
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    • v.51 no.6
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    • pp.666-670
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    • 2013
  • Recovery method of silicon wafer from defective products generated from manufacturing process of silicon solar cells was studied. The removal effect of the N layer and antireflection coating (ARC) of the waste solar cell were investigated at room temperature ($25^{\circ}C$) by variation of concentration of $H_3PO_4$, $NH_4HF_2$, and concentration and types of chelating agent. Removal efficiency was the best in the conditions; 10 wt% $H_3PO_4$ 2.0 wt% $NH_4HF_2$, 1.5 wt% Hydantoin. Increasing the concentration of $H_3PO_4$, the surface contamination degree was increased and the thickness of the silicon wafe became thicker than the thickness before surface treatment because of re-adsorption on the silicon wafer surface by electrostatic attraction of the fine particles changed to (+). The etching method by mixed solution of $H_3PO_4$-$NH_4HF_2$-chelating agents was expected to be great as an alternative to conventional RCA cleaning methods and as the recycle method of waste solar cells, because all processes are performed at room temperature, the process is simple, and less wastewater, the removal efficiency of the surface of the solar cell was excellent.

Effect of Carbon Dioxide in Fuel on the Performance of PEMFC (연료중의 이산화탄소 불순물에 의한 고분자전해질연료전지의 성능변화 연구)

  • Seo, Jung-Geun;Kwon, Jun-Taek;Kim, Jun-Bom
    • Journal of the Korean Electrochemical Society
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    • v.11 no.1
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    • pp.42-46
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    • 2008
  • Even though fuel cell have high efficiency when pure hydrogen from gas tank is used as a fuel source, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, $CH_4$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of the electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. This study is aimed at investigating the effect of carbon dioxide on fuel cell performance. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run(10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC).

Studies on the Improvement of Packaging of Retorted Samgyetang (레토르트 삼계탕의 포장 개선을 위한 연구)

  • Lee, Jin-Hwan;Lee, Keun-Taik
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.15 no.2
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    • pp.49-54
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    • 2009
  • The effects of filling temperatures of broth and degassing method on the residual oxygen content and gas composition in the pouch and physical strength of packaging material for Samgyetang depending on the contamination of broth on the sealing layer and sterilization process were investigated. The residual oxygen content in the broth and the oxygen proportion in the headspace of package were decreased with the increase of broth temperature at filling into the pouch from 50 to 100. When the products were packaged as air-contained (Air), manually squeezed the upper side of package out to minimize the headspace (Degas) and flushed with nitrogen gas ($N_2$-Flushing) while maintaining the broth temperatures of Samgyetang at 50 or 85. The residual oxygen content and oxygen proportion were increased in the order of $N_2$-Flushing

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Studies on Salmonella enteritidis Contamination in Chicken Egg using Confocal Scanning Laser Microscopy (Confocal Scanning Laser Microscopy 를 이용한 계란에서의 Salmonella enteritidis 오염 연구)

  • Jang, Keum-Il;Park, Jong-Hyun;Kim, Kwang-Yup
    • Korean Journal of Food Science and Technology
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    • v.31 no.3
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    • pp.771-777
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    • 1999
  • The structural function of three egg membrane layers and cuticle layer, and the effectiveness of 5 film coatings (chitosan, starch, gelatin, dextrin, mineral oil) on the prevention of Salmonella enteritidis penetration was investigated using confocal scanning laser microscopy (CSLM). Diameters of outer membrane fibers, inner membrane fibers and limiting membrane particles in eggshell were $1.5{\sim}7.2$, $0.8{\sim}2.0$ and $0.1{\sim}1.4\;{\mu}m$, respectively and average thicknesses were 10.0, 3.5, $3.6\;{\mu}m$, respectively. Average thickness of cuticle layer was $6.0\;{\mu}m$ and cuticle layer covered $40{\sim}80%$ of total eggshell surface. Average coating films thickness for chitosan, starch, gelatin, dextrin and mineral oil were 2.2, 2.5, 3.9, 3.6 and $5.0\;{\mu}m$, respectively. After immersion process eggshell surface was almost completely covered by coating films. Chitosan coating was most effective among 5 film coatings in inhibiting growth of Salmonella enteritidis. Penetration process of Salmonella enteritidis through eggshell was investigated by multicolor imaging using CSLM and plate counting. Cuticle layer was the most important structure in blocking the penetration. Among 5 film coatings, chitosan showed the best and similar effectiveness with cuticle layer.

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Proposed Methodological Framework of Assessing LID (Low Impact Development) Impact on Soil-Groundwater Environmental Quality (저영향개발(Low Impact Development) 기법 적용 지역 토양·지하수 환경 영향 평가 방법론 제안 연구)

  • Kim, Jongmo;Kim, Seonghoon;Lee, Yunkyu;Choi, Hanna;Park, Joonhong
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.7
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    • pp.39-50
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    • 2014
  • The goal of this work is to develop a framework of methods to entirely evaluate effects of LID (Low Impact Development) on soil-groundwater environmental quality as well as land-scape and ecological factors. For this study, we conducted an extensive literature review. As outcomes, soil-groundwater environmental quality is newly conceptualized as a comprehensive index reflecting (i) groundwater pollution sensitivity (hydrogeological factor), (ii) biochemical contamination, and (iii) biodegradability. The methods of classifying and indexing is shown by combining selection of the items to be measured for soil-groundwater environmental quality and integrating the resulted items comprehensively. In addition, from soil-groundwater environmental quality, land-scape and ecological factors in existing environmental impact assessment a method was developed an overall index which can evaluate effects to environment by using GIS (Geographic Information System) and AHP (Analytic Hierachy Process). For optimizing LID planning, designing and post-evaluation, LCIA (Life Cycle Impact Assessment) was regarded as an appropriate method.

The Optimization of Ozone Solubility and Half Life Time in Ultra Pure Water and Alkaline Solution on Semiconductor Wet Cleaning Process (반도체 습식 세정 공정 중 상온의 초순수와 염기성 수용액 내에서 오존의 용해도 최적화)

  • Lee Sang-Ho;Lee Seung-Ho;Kim Kyu-Chae;Kwon Tae-Young;Park Jin-Goo;Bae So-Ik;Lee Gun-Ho;Kim In-Jung
    • Journal of the Semiconductor & Display Technology
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    • v.4 no.4 s.13
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    • pp.19-26
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    • 2005
  • The process optimization of ozone concentration and half life time was investigated in ultra pure water and alkaline solutions for the wet cleaning of silicon wafer surface at room temperature. In the ultra pure water,. the maximum concentration (35 ppm) of ozone was measured at oxygen flow rate of 3 liters/min and ozone generator power over 60%. The half life time of ozone increased at lower power of ozone generator. Additive gases such as $N_2$ and $CO_2$ were added to increase the concentration and half life time of ozone. Although the maximum ozone concentration was higher with the addition of $N_2$ gas, a longer half life time was observed with the addition of $CO_2$. When $NH_4OH$ of 0.05 or 0.10 vol% was added in DI water, the pH of the solution was around 10. The addition of ozone resulted in the half life time less than 1 min. In order to maintain high pH and ozone concentration, ozone was continuously supplied in 0.05 vol% ammonia solutions. 3 ppm of ozone was dissolved in ammonia solutions. The static contact angle of silicon wafer surface became hydrophilic. The particle removal was possible alkaline ozone solutions. The organic contamination can be removed by ozonated ultra pure water and then alkaline solution containing ozone can remove the particles on silicon surface at room temperature.

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Changes of Indicator Microorganisms and Pathogenic Bacteria in Spinach during Cook-Chill Process (시금치의 cook-chill 가공 중 오염지표균 및 병원성세균의 변화)

  • Kim, Hye-Jung;Park, Jae-Kap;Lee, Dong-Sun;Paik, Hyun-Dong
    • Korean Journal of Food Science and Technology
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    • v.34 no.5
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    • pp.927-930
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    • 2002
  • Spinach minimally processed using cook-chill and sous vide techniques was vacuum-packed in low gas permeable plastic film, pasteurized at $70^{\circ}C$ for 2 min, cooled rapidly at $3^{\circ}C$, and stored at 3 and $10^{\circ}C$. Contents of mesophilic bacteria, psychrophilic bacteria, anaerobic bacteria, spore-forming bacteria, total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were measared to identify the degree of food contamination. Number of mesophilic bacteria, detected at $2.2{\times}10^8\;cfu/g$ in raw spinish, decreased to about $6.0{\times}10^3\;cfu/g$ after cook-chill process. During the storage at 3 or $10^{\circ}C$, levels of mesophilic, psychrophilic and anaerobic bacteria increased, whereas total coliforms, yeast and molds, fecal Streptococcus, and Enterobacteriacea were not detected. Twelve strains of Aeromonas hydphila, Escherichia coli O157:H7, Plesiomonas shigelloides, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Yersinia enterocolitica, Bacillus cereus, Campylococcus spp., Clostridium perfringens, Listeria monocytogenes, and Staphylococcus aureus were examined for detecting the presence of pathogenic bacteria in spinach. B. cereus and C. perfringens were isolated from raw, washed, and cook-chilled spinach, whereas A. hydrophila was isolated only from washed spinach. S. aureus was isolated from raw and washed spinach, but not from cook-chilled spinach. Other pathogenic organisms were not detected in raw, washed, and cook-chilled spinach.

Study on the Development and Property of Epoxy Putty with Excellent Low Shrinkage and Cutting Force Using Mercaptan Type and Diamine Type (Mercaptan계와 Diamine계를 이용한 저수축·절삭력이 우수한 Epoxy Putty의 개발 및 물성에 관한 연구)

  • Oh, Seung-Jun;Wi, Koang-Chul
    • Journal of Adhesion and Interface
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    • v.16 no.4
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    • pp.137-145
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    • 2015
  • This study aimed to develop epoxy putty as a multi-purpose connection and restoration material that can be used for material-specific restoration work such as metal, wood, ceramics, earthenware and stone artifacts by replacing synthetic resins currently being used for preservation treatment of cultural assets. Existing synthetic resins have the issue of cutting force resulting from high strength, deflection resulting from long hardening time, contaminating the surface of artifacts through staining on tools or gloves and need for re-treatment resulting from material discoloration. Accordingly, paste type restoration material most widely being used in the field of cultural assets preservation treatment was selected and examined the property to select it as an object of comparison. Based on such process, epoxy putty was developed according to the kind of agent, hardener and filler. For the purpose of solving the issues of existing material and allowing the epoxy putty developed to have similar property, property experiments were conducted by selecting agents and hardeners with different characteristics and conditions. The study findings showed that both kinds are paste type that improved work convenience and deflection issue as a result of their work time of within 5~10 minutes that are about 3~10 times shorter than that of existing material. In regards to wear rate for increasing cutting force, it improved by about 3 times, thereby allowing easy molding. For the purpose of improving the issue of surface contamination that occurs during work process, talc and micro-ballon were added as filler to reduce the issue of stickiness and staining on hand. Furthermore, a multi-purpose restoration material with low shrinkage, low discoloration and high cutting force was developed with excellent coloring, lightweight and cutting force features.

The Soil and Water Pollution caused by the Weathering of Pyrophyllite Deposits: Upstream Part of Hoidong Water Reservoir in Pusan (납석광산에서 발생하는 토양 및 수질오염 실태 : 부산광역시 회동수원지 상류 지역)

  • 박맹언;김근수
    • Journal of Environmental Science International
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    • v.7 no.2
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    • pp.149-156
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    • 1998
  • Enoronmental problems caused by certain geologic conditions Include pollution of soil by heavy metal, acidization of souls , acid mine drainage, Pound-water pollution, and natural radioactivity, as well as zoo-logical hazards such as landslide and subsidence. The acrid mine drainage contains large amount of heavy metals nO, therefore. cause serious pollution onto the nearby drainage systems and soils. In spite of this prospective environmental danger, few studies have been done on the acid mine drainage derived from non-metallic ore deposits such as pyrophyllitefNapseok) deposits. The sudo-bearing pyrophyllite ores, alteration zones, and mine talllngs of pyrophylllte deposits produce acrid mine drainage by the okidation of weathering. Compared to the fresh host rocks, the ores and altered rocks of pyrophyllite deposits produce acidic solution which contain higher amount of heavy metals because of OeP lower buffering capacity to acrid solution. The pus of urine water and nearby stream water of pyrophyllite deposits are 2.1~3.7, which are strong- ly acidic and much lower than that (6.2~7.2) of upstream water and than that (6.8~7.6) of the stream water derived from the non-mineralized area. This study reveals that this acrid mine drainage can affect the downstream area which is 8km far from the pyrophyllite deposits, even though the drain Is diluted with abundant non-contaminated river water This suggmists that not only acid mine drainage but also the sulfide-bearing sediments originated from the pyrophyllite deposits move downstream and form acidic water through continuous oxidation reaction. The heavy metals such as Pb, Zn, Cu, Cd, Nl, Mn and Fe are enriched In the mine water of low pH, and their contents decrease as the pH of mine water Increases because of the Influx of fresh stream wainer. SoUs of the Pyrophyulte deposits are characterized by high contents of heavy metals. The stream sediments containing the yellowish brown precipitates formed by neutralization of acid mine drainage occur in all parts of the stream derived from the pyrophyllite deposits, and the sediments also contain high amounts of heavy metals. In summary, the acid mine drainage of the pyrophyllite deposits is located in the upstream part of Hoidong water reservoir in Pusan contains large amounts of heavy metals and flows into the Holdong water reservoir without any purification process. To protect the water of Holdong reservoir, the acid mine drainage should be treated with a proper purification process.

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Remediation of Petroleum-Contaminated Soil by a Directly-Heated Thermal Desorption Process (직접 가열식 열탈착 공정을 이용한 유류오염토양의 정화)

  • Min, Hyeong-Sik;Yang, In-Ho;Jeon, Sang-Jo;Kim, Han-S.
    • Journal of Soil and Groundwater Environment
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    • v.14 no.5
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    • pp.62-70
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    • 2009
  • A field soil highly contaminated with petroleum hydrocarbons (JP-8 and diesel fuels) was employed for its remediation by a lab-scale thermal desorption process. The soil was collected in the vicinity of an underground storage tank in a closed military base and its contamination level was as high as 4,476 ppm as total petroleum hydrocarbon (TPH). A lab scale directly-heated low temperature thermal desorption (LTTD) system of 10-L capacity was developed and operated for the thermal treatment of TPH contaminated soils in this study. The desired operation temperature was found to be approximately $200-300^{\circ}C$ from the thermal gravimetric analysis of the contaminated field soils. The removal efficiencies higher than 90% were achieved by the LTTD treatment at $200^{\circ}C$ for 10 min as well as at $300^{\circ}C$ for 5 min. As the water content in the soils increased and therefore they were likely to be present as lumps, the removal efficiency noticeably decreased, indicating that a pre-treatment such as field drying should be required. The analysis of physical and chemical properties of soils before and after the LTTD treatment demonstrated that no significant changes occurred during the thermal treatment, supporting no needs for additional post-treatments for the soils treated by LTTD. The results presented in this study are expected to provide useful information for the field application and verification of LTTD for the highly contaminated geo-environment.