• Title/Summary/Keyword: reduction synthesis

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Analysis of Vibration Transmissibility for Compressor of Refrigerator by Vector Synthesis Method (벡터합성법에 의한 냉장고 압축기의 진동전달 해석)

  • 오재응;조준호;김진동
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.1
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    • pp.14-21
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    • 1995
  • General Mechanical Structures have various and complex vibration transmission paths. In order to identify the mechanism of vibration transmission. The correct estimation of exciation forces and the exact modeling of transmission paths are required. In this paper, vector synthesis technique is employed to identify the characteristics of vibration input and it's transmission to body structure for the mounting system of a compressor in a refrigerator. Vibration reduction efficiency of each transmission path is evaluated by comparing individual vector components obtained before and after the paths from experimental research. The degree of effect is used to estimate the contribution of vibration input components to total output. And this paper presents a new technique based on simulation studies using vector synthesis dragram, by which the effects of change of the magnitude and phase of transmission paths can be predicted.

Inhibition of Corticosterone-induced Muscle Protein Synthesis by the Anabolic Steroid Nandrolone Phenylpropionate in Female Rats (아나보릭스테로이드인 Nandrolone Phenylpropionate가 암컷 쥐에서 코티코스테론에 의해 야기된 근육단백질 쇠퇴와 근육단백질 합성율 감소에 미치는 영향)

  • 주종재
    • Journal of Nutrition and Health
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    • v.29 no.8
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    • pp.867-873
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    • 1996
  • This study was undertaken to determine whether the anabolic steroid nandrolone phenylpropionate(NPP) can inhibit the muscle atrophy and reduction in muscle protein synthesis caused by glucocorticoids in female rates. Daily injections of 50mg/kg of corticosterone for eight days induced significant reductions in body weight gain and protein without affecting food intake. The mass, protein and RNA content, ratio of RNA to protein, and fractional rate of protein synthesis, measured in vivo, of gastrocnemius muscle were all significantly reduced by corticosterone treatement. Simultaneous administration of NPP at a dose of 10mg/kg with corticosteorne (50mg/kg) fully inhibited the reductions in the mass, protein and RNA content of gastrocnemius muscle, and body weight gain and protein with no alteration in food intake but the reduction in fractional rate of muscle protein syntheis was only partially prevented. The results indicate that the anabolic steroid nandrolone phenylpropionate is capable of preventing muscle atrophy in female rats treated with excess corticosterion.

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Synthesis of $\beta$-Sialon Powder from Fly Ash (Fly Ash를 이용한$\beta$-Sialon 분말합성)

  • 최희숙;노재승;서동수
    • Journal of the Korean Ceramic Society
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    • v.33 no.8
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    • pp.871-876
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    • 1996
  • It is believed that fly ash could be suitable for preparing the sialon by carbothermal reduction method because the total amount of SiO2 and Al2O3 is above 80% and the unburned residual carbon is above 5% within the fly ash. The effects of reaction temperature (1350, 1400, 145$0^{\circ}C$) reaction time (1, 5, 10 hours) and the amount of carbon additions (C/SiO2=2, 3, 4 mole) on the $\beta$-sialon synthesis were obserbed, It was conformed that $\beta$-sialon (Z=2.15~2.18) was formed as major phase under all of the synthesis conditions and small amount of Si2ON2 SiC, AlN and Si3N4 was formed depending on the synthesis conditions. FeSix intermetal-lic compound was formed above 140$0^{\circ}C$ reaction temperature due to the large amount of iron oxides within the raw fly ash.

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Synthesis of FDR-SPC Resin and PIV Measurement for Frictional Drag-reduction (마찰저항 저감을 위한 고분자 수지 합성 및 PIV 유동장 계측)

  • Chung, Sungwoo;Kim, Eunyoung;Chun, Ho Hwan;Park, Hyun;Lee, Inwon
    • Journal of the Korean Society of Visualization
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    • v.12 no.1
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    • pp.49-53
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    • 2014
  • In this study, a novel FDR-SPC is first synthesized in this study. The drag reducing functional radical such as PEGMA (Poly(ethylene) glycol methacrylate) has been utilized to participate in the synthesis process of the SPC. The types of the baseline SPC monomers, the molecular weight and the mole fraction of PEGMA were varied in the synthesis process. The resulting SPCs were coated to the substrate plates for the subsequent hydrodynamic test for skin friction measurement. In a low-Reynolds number flow measurement using PIV (Particle Image Velocimeter), a significant reduction in Reynolds stress was observed in a range of specimen, with the maximum drag reduction being 15.9% relative to the smooth surface.

Synthesis of Copper Nanoparticles by a Chemical Reduction Method (화학적 환원법에 의한 구리 나노분말 합성)

  • Choi, Min Woo;Bae, Min Hwan;Ahn, Jung-Ho
    • Journal of Powder Materials
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    • v.23 no.3
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    • pp.228-234
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    • 2016
  • Copper nanoparticles attract much attention as substitutes of noble metals such as silver and can help reduce the manufacturing cost of electronic products due to their lower cost and good conductivity. In the present work, the chemical reduction is examined to optimize the synthesis of nano-sized copper particles from copper sulfate. Sodium borohydride and ascorbic acid are used as reducing and antioxidant agents, respectively. Polyethylene glycol (PEG) is used as a size-control and capping agent. An appropriate dose of PEG inhibits the abnormal growth of copper nanoparticles, maintaining chemical stability. The addition of ascorbic acid prevents the oxidation of nanoparticles during synthesis and storage. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate the size of the synthesized nanoparticles and the coordination between copper nanoparticles and PEG. For chemical reduction, copper nanoparticles less than 100 nm in size without oxidized layers are successfully obtained by the present method.

Solution Plasma Synthesis of BNC Nanocarbon for Oxygen Reduction Reaction

  • Lee, Seung-Hyo
    • Journal of the Korean institute of surface engineering
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    • v.51 no.5
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    • pp.332-336
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    • 2018
  • Alkaline oxygen electrocatalysis, targeting anion exchange membrane alkaline-based metal-air batteries has become a subject of intensive investigation because of its advantages compared to its acidic counterparts in reaction kinetics and materials stability. However, significant breakthroughs in the design and synthesis of efficient oxygen reduction catalysts from earth-abundant elements instead of precious metals in alkaline media still remain in high demand. One of the most inexpensive alternatives is carbonaceous materials, which have attracted extensive attention either as catalyst supports or as metal-free cathode catalysts for oxygen reduction. Also, carbon composite materials have been recognized as the most promising because of their reasonable balance between catalytic activity, durability, and cost. In particular, heteroatom (e.g., N, B, S or P) doping on carbon materials can tune the electronic and geometric properties of carbon, providing more active sites and enhancing the interaction between carbon structure and active sites. Here, we focused on boron and nitrogen doped nanocarbon composit (BNC nanocarbon) catalysts synthesized by a solution plasma process using the simple precursor of pyridine and boric acid without further annealing process. Additionally, guidance for rational design and synthesis of alkaline ORR catalysts with improved activity is also presented.