• 한국환경과학회지
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• 제29권12호
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• pp.1205-1211
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• 2020

In this study, the applicability of reduction-oxidation-linked treatment was evaluated for nitrobenzene and a by-product by analyzing the reaction kinetics. Nitrobenzene showed very low reactivity to persulfate that was activated using various methods. Nitrobenzene effectively reacted through the reduction process using Zero-Valent Iron (ZVI). However, aniline, a toxic substance, was produced as a by-product. Reduction-oxidation-linked treatment is a method that can allow the oxidative degradation of aniline after reducing nitrobenzene to aniline. The experimental results show improved reactivity and complete decomposition of the by-product. Improved reactivity and decomposition of the by-product were observed even under conditions in which the reduction-oxidation reaction was induced simultaneously. No activator was injected for persulfate activation in the process of reducing oxidant linkage, and the activation reaction was induced by ferrous iron eluted from the ZVI. This indicates that this method can be implemented relatively simply.

• Elastomers and Composites
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• 제51권1호
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• pp.38-42
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• 2016

For improving the heat loss of a refrigerator around door gasket, it is very important to reduce the amount of rubber magnet used, of which thermal conductivity is much higher than the plastics, and enhancing the magnetic properties of rubber magnet itself is crucial for this. In the present study, therefore, a relationship between the optimum conditions of rubber magnet fabrication process and raw material compositions in the ferrite powder/CPE binder compounds was investigated for finding a way to enhance the magnetic properties of rubber magnet. Magnetic attraction forces of a sample rubber magnet was measured as function of distance, and thermal properties of the sample ferrite powder/CPE binder compound were analyzed with TG/DTA thermal analyzer. As a results, a rubber magnet strip with enhanced magnetic properties was expected to be fabricated, of which raw material compound was prepared by compounding with higher ferrite magnetic powder concentration.

• 설비공학논문집
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• 제13권12호
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• pp.1266-1274
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• 2001

Heat transfer phenomena during melting process of the phase change material (ice) was studied by numerical analysis and experiments. In a horizontal ice storage tube, the natural convection caused an increase in melting rate. However, the reduction of the heating surface area caused a decrease in melting rate. Therefore, during the melting process of ice in a horizontal cylinder, the reduction of the heating surface area should be considered. Under the same heating wall and initial water temperature condition, the melting rate became higher for $V_s/V_tot/=0.545 \;than \;that\; for\; V_s/V_tot$/=1.00 due to the difference in the reduction of heating surface area. A modified melting model considering the equivalent thermal conductivity of liquid phase and volume reduction was proposed. The results of the model were compared with the measured values and found to be in good agreement.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.997-1003
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• 2008

Viral safety is a prerequisite for manufacturing clinical antihemophilic factor VIII concentrates from human plasma. With particular regard to the hepatitis A virus (HAV), a terminal dry-heat treatment ($100^{\circ}C$ for 30 min) process, following lyophilization, was developed to improve the virus safety of a solvent/detergent-treated antihemophilic factor VIII concentrate. The loss of factor VIII activity during dry-heat treatment was of about 5%. No substantial changes were observed in the physical and biochemical characteristics of the dry-heat-treated factor VIII compared with those of the factor VIII before dry-heat treatment. The dry-heat-treated factor VIII was stable for up to 24 months at $4^{\circ}C$. The dry-heat treatment after lyophilization was an effective process for inactivating viruses. The HAV, murine encephalomyocarditis virus (EMCV), and human immunodeficiency virus (HIV) were completely inactivated to below detectable levels within 10 min of the dry-heat treatment. Bovine herpes virus (BHV) and bovine viral diarrhea virus (BVDV) were potentially sensitive to the treatment. However porcine parvovirus (PPV) was slightly resistant to the treatment. The log reduction factors achieved during lyophilization and dry-heat treatment were ${\geq}5.55$ for HAV, ${\geq}5.87$ for EMCV, ${\geq}5.15$ for HIV, 6.13 for BHV, 4.46 for BVDV, and 1.90 for PPV. These results indicate that dry-heat treatment improves the virus safety of factor VIII concentrates, without destroying the activity. Moreover, the treatment represents an effective measure for the inactivation of non-lipid-enveloped viruses, in particular HAV, which is resistant to solvent/detergent treatment.

• 청정기술
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• 제4권2호
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• pp.41-53
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• 1998

열처리시 대부분 연소로의 경우는 대기중에서 열처리되기 때문에 표면에 산화피막이 형성된다. 그러므로 이의 제거를 위해 숏블라스트(Shot blasting) 같은 연마와 산세공정이 추가되므로 공정소요 시간이 오래 걸리고 연마분진으로 인한 작업장의 환경악화는 물론 제품의 형상이 복잡하거나, 강관의 내면은 처리가 더욱 어려워진다. 그러므로 본 연구에서는 연소로 내부에 고온 내구성을 지닌 강재로 내부로를 제작하고 내부 분위기를 불활성분위기로 조절하여 산화피막의 형성을 저감시키기 위하여 연구하였다. 전기로에서 실험된 시편의 SEM, EPMA, EDX의 분석결과 산화피막이 저감됨을 알 수 있었고, 또한 진공로와의 처리품질 비교에서도 진공로와 유사한 광휘성을 나타내었다. 연구결과 개선공정을 적용하기 위해 내부로는 원통형에 재질은 SBB410으로 제작하고 분위기 가스가 유입되는 가스관로는 STS310으로 하부에서 유입시키는 방식이 가장 효율적일 것으로 도출되었다. 기적용된 사업장의 절감효과를 적용한 경제성 평가에서 연간 약 4천만원 이상의 절감효과가 기대되고, 청정기술적 효과로는 열처리 이후 제품의 구조상 제거되지 못하는 산화피막에 대한 대책 수립 및 산화피막 폐기물발생 저감, 그리고 공정단축과 작업환경의 개선효과를 볼 수 있다.

• 전기학회논문지
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• 제66권11호
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• pp.1600-1604
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• 2017

Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile and many other applications due to their excellent physical and electronic properties. Especially, Mo-Cu composites with 5~20 wt% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength and prominent electrical and thermal conductivity. In most of the applications, high dense Mo-Cu materials with homogeneous microstructure are required for high performance, which has led in turn to attempts to prepare ultra-fine and well-dispersed Mo-Cu powders in different ways, such as spray drying and reduction process, electroless plating technique, mechanical alloying process and gelatification-reduction process. However, most of these methods were accomplished at high temperature (typically degree), resulting in undesirable growth of large Cu phases; furthermore, these methods usually require complicated experimental facilities and procedure. In this study, Mo-Cu alloying were prepared by planetary ball milling (PBM) and spark plasma sintering (SPS) and the effect of Cu with contents of 5~20 wt% on the microstructure and properties of Mo-Cu alloy has been investigated.

• 열처리공학회지
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• 제4권2호
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• pp.9-18
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• 1991

Among the many maunfactured processes of producing multi filamentary composites, in situ process is widely used owing tv its simplicity and easyness of mass production. In this study, the mechanical and electromagnetic properties of Cu-Fe composite materials was investigated. The tensile strength of the Cu-Fe wires increased as the Fe content and reduction ratio were increased. The Cu-30 wt%Fe composites had the best properties in terms of figure merits compared to the other Cu-Fe composites made in this study or the commercially manufactured 6/1 ACSR cables of Cu cable. The coercivity was decreased by increasing Fe content, but the squareness was increased greatly. As increasing reduction ratio, the coercivity and squareness increased up to the maximum points, and then decreased. For example, the maximum values were obtained at $0.09mm{\phi}$ for Cu-30 wt%Fe composites and at $0.066mm{\phi}$ for Cu-45 wt%Fe composites. The magnetic property of Cu-Fe wires produced by precipitation treatment was higher than that of Cu-Fe wires produced by thermomechanical treatment. By annealing Cu-Fe wires after drawing process, the coercivity, remanence and squareness were improved.

• 한국분말재료학회지
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• 제10권5호
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• pp.337-343
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• 2003

Nanostructured Cu-$Al_2O_3$ composite powders were synthesized by thermochemical process. The synthesis procedures are 1) preparation of precursor powder by spray drying of solution made from water-soluble copper and aluminum nitrates, 2) air heat treatments to evaporate volatile components in the precursor powder and synthesis of nano-structured CuO + $Al_2O_3$, and 3) CuO reduction by hydrogen into pure Cu. The suggested procedures stimulated the formation of the gamma-$Al_2O_3$, and different alumina formation behaviors appeared with various heat treating temperatures. The mean particle size of the final Cu/$Al_2O_3$ composite powders produced was 20 nm, and the electrical conductivity and hardness in the hot-extruded bulk were competitive with Cu/$Al_2O_3$ composite by the conventional internal oxidation process.

• 한국기계가공학회지
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• 제10권6호
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• pp.1-8
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• 2011

Recently, super heat-resistant alloy Inconel 600 come into spotlight as the material of airplane parts but this material causes lots of problems that is, reduction of machinability and attritious wear and breakage of cutting tool during turning processing due to high temperature strength and cohesion between tool material and Inconel 600. Therefore, in this study, it was purposed to determine tool material kind and to select of proper cutting range when turning process was carried out for Inconel 600. In order to these Purpose, coated carbide tool and ceramic tool was used in this experiment and the machinability of Inconel 600 was investigated from perspective of the cutting force, chipping and wear of tool and deposition phenomenon of chip.

• 한국정밀공학회지
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• 제28권12호
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• pp.1353-1358
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• 2011

LAT(Laser Assisted Turning) is a method that applies a machining process after softening a workpiece in which a preheating process is locally applied to its machining section using laser heat source. LAT shows several advantages, such as high productivity, reduction of manufacturing cost, high quality. Analysis of temperature distribution after preheating for LAT is very difficult due to its very small heat input area and large energy and its movement. Also, the LAT for a square bar is more difficult because the shape of a laser heat source can be changed according to the rotation of the workpiece. In this study, thermal analysis for LAT of square bar was performed using laser heat source projection method. And, the analysis results were compared with the results of the prior study of numerical calculation method. It is thus shown that the proposed method is efficient for the thermal analysis of a shaped bar.