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        검색결과 35

        1.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the performance evaluation of Al-graphene nanoplatelets (GNP) composites surface engineered by a modified friction stir processing (FSP) is reported. Here, multiple micro channels (MCRF) are used to incorporate GNPs in the aluminium matrix instead of a single large groove (SCRF) that is usually used in conventional FSP. With the MCRF approach, ~ 18% higher peak temperature (compared to SCRF) was observed owing to the presence of aluminium sandwiched between consecutive microgrooves and higher heat accumulation in the stir zone. The MCRF approach have significantly reduced the coefficient of friction and wear rates of the processed composites by ~ 14% and ~ 57%, respectively as compared to the SCRF approach. The proposed reinforcement filling method significantly improves the particle dispersion in the matrix, which in turn changes the adhesion mode of wear in SCRF to abrasive mode in MCRF fabricated composites. The uniformly squeezed out GNP tribolayer prevented the direct metal to metal contact between composite and its counterpart which have effectively reduced the deterioration rates.
        4,600원
        2.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminium metal matrix composites (AMMCs) are the fastest developing materials for structural applications due to their high specific weight, modulus, resistance to corrosion and wear, and high temperature strength. Carbon nanotubes (CNTs) is known as the material of the twenty-first century for its various applications in structural components for their high specific strength as well as functional materials for their exciting thermal and electrical characteristics. The present study comprise a systematic literature review of Al/CNT nanocomposites fabricated through a solid state friction stir processing. The present review is primarily focussed on the dispersion and survivability of CNTs in the Al matrix because these are the key factors in deciding the mechanical properties of the fabricated composite. Additionally, the formability, weldability and machinability of the FSPed fabricated composites reinforced with CNTs are also summarised here. Based on the detailed literature review, following research gaps are identified which require a critical and more focussed attention of the scientific community working in this research area: (i) the presence of agglomeration or clustering of CNTs in the composite, (ii) survivability and shortening of CNTs during FSP, (iii) interfacial reactions or the formation of reaction products (such as Al4C3) between Al matrix and CNTs, and (iv) the unidirectional alignment of CNTs in the fabricated composite. Important suggestions for further research in effective dispersion of CNTs with its preserved structure by FSP are also provided.
        7,800원
        3.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fecal calprotectin is a noninvasive marker of gut inflammation and has been widely utilized in human gastrointestinal diagnostics. This marker, however, has not been extensively utilized in porcine samples. The aim of this study was to optimize a protocol for the extraction of porcine fecal calprotectin, and to the best of our knowledge this is the first study to be conducted in this regard. Freshly collected swine fecal samples were used in this study. We determined the variability of three commercial ELISA assays in the recovery of porcine fecal calprotectin. We further studied the effect of dilution factor and roller shaker homogenization on the yield of calprotectin from swine fecal samples. Calprotectin recovery was significantly different(p<0.05) across the three commercial assays with MBS033848 having a greater recovery compared to DAEF-012 and calprest. Fecal calprotectin yield increased with an increase in dilution factor with maximum recovery at 1:250. Furthermore, homogenization of fecal sample extracts using a roller shaker for tubes for 30 min led to a 30.75% relative increase in calprotectin yield. Further increase in shaking time(at 60 min) led to a reduced calprotectin recovery. Calprotectin recovery ratio was 130.8% and 101.4% at 30 min and 60 min homogenization respectively. In our conclusion, we observed that various factors affect the recovery of porcine fecal calprotectin, and therefore the researcher should double check certain parameters in regard to the type of kit, the dilution factor and homogenization time if reliable and reproducible results are to be obtained. Results of the present study provide useful information on a non-invasive protocol to veterinarians and researchers in examining and monitoring swine gut healthusing the fecal calprotectin.
        4,300원
        5.
        2018.07 구독 인증기관·개인회원 무료
        The Theory of Value Drivers, or Value Driver Theory (Wendee, 2011), is useful in understanding the value creation process in any enterprise. Innovation and strategy are important components in the value creation process. This research, which is based on Value Driver Theory, explored the role that innovation and strategy have in the value creation process and how they are employed in creating enterprise value. Value Driver Theory was discovered using two different, but compatible, research methodologies. The qualitative study used to discover Value Driver Theory explored the effect of business value drivers on the valuation of businesses in the United States and proposed a theory of value drivers. The Value Driver Theory study used two research methods – grounded theory and the Delphi method - to explore the effect of business value drivers on the valuation of businesses in the U.S. and to propose a theory of value drivers. In addition to a list of 72 individual value drivers, which includes innovation and strategy, the theory of value drivers presents a comprehensive value driver possibilities frontier and value driver chain, both of which are part of and are used to explain the theory of value drivers. The theory of value drivers is comprised of 28 propositions that work in concert with the possibilities frontier, the value driver chain, and other elements that are described in the paper. The Value Driver Theory paper differs from other studies as follows: First, the paper significantly extends the notions, ideas, and concepts from previous studies on value drivers. Second, the paper creates a comprehensive classification scheme for value drivers and has identified many more characteristics and properties of value drivers than previous studies. Third, the study identified 72 specific value drivers through the literature review and the Delphi study. Fourth, the paper consolidates the material from the literature review and the result of the research conducted through the Delphi and grounded theory studies and codifies it into the theory of value drivers. Subsequent to the publication of the paper on Value Driver Theory, new conceptual frameworks and tools have been developed to enhance the usefulness of Value Driver Theory in evaluating the enterprise value creation process. These conceptual frameworks and research tools were explored in the current study in general terms; and particularly as to how they relate to and enhance the use of innovation and strategy in the value creation process.
        6.
        2018.05 구독 인증기관·개인회원 무료
        In this paper the authors would like to present and share the measurements of load spectra and their modelling for pavement design purposes in the Mexican road network, which due to the intense level of trade with the United States present a very high percentage of heavy vehicles in the flow of vehicles and with high levels of load. Examples of these measurements are given in the country's main transport corridors. Damage spectra are also presented that are associated to each of the different axle types (i.e., single, dual, tandem, tridem or another one) by computing for instance the Miner damage coefficient in the same load ranges used in the definition of the load spectra. Is this frequency distribution of the Miner damage coefficient that is called damage spectra. The damage spectra seem to be a very useful tool to evaluate the pavement expected damage, i.e., rutting or fatigue cracking, induced for a given axle type. Moreover, it can be showed that there is a direct relationship between the forms in load and damage spectra. Some examples are presented to illustrate the damage spectra computations. The incorporation of these load spectra into mechanistic design methodologies and their implications in the definition of public policies for the preservation of the road network are discussed.
        7.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to evaluate the influencing factors that affect the reproductive performance of cows at the Monirampur upazila in Jessore district of Bangladesh. A total of 224 cows were brought to the upazila livestock hospital for artificial insemination (AI). The cows were inseminated between 12 to 18 hours from the onset of estrus and data was obtained from the owner. Out of 224 cows, 133 became pregnant and 91 were non pregnant. In this study, the overall pregnancy rate was 59.29%. Among the age variability, the highest pregnancy rate (70.27%) was at the age of 4 years old. In case of breed variation, the highest pregnancy rate was observed in local breed (69.07%) compared with other crossbred cows. Hence the breed variations significantly influence the conception rate of cows. According to the parity, we found that the pregnancy rate was increasing with their parity but decreasing after 4th parity. The highest conception rate was observed in 3rd parity (67.74%) which was significantly higher than that of heifers (Parity-0). Here we also found that the types of bull semen used for AI had no significant effect for pregnancy rate. The skills of AI technician for AI to cows were significantly affecting the pregnancy rate. However, this study is not enough for rating and comment about the reproduction performance of cows. Therefore, further extensive study is needed for rating and recommendation for the cattle up gradation at that particular area.
        4,000원
        8.
        2015.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        농진청에서 수행하고 있는 아프리카 국제협력프로그램인KAFACI 사업의 일환으로 우간다 등 8개국에 ‘통일형 다수성벼 품종개발’ 사업을 추진하고 있다. 이를 위해 아프리카에서정상적인 생육과 수량을 나타내는 다수성 통일형 품종인 밀양23호와 아프리카의 재래종인 O. glaberrima를 이용하여 밀양23호의 유전적배경을 보유한 근동질 계통인 BC4F1을 육성하고, 약배양을 통해 유전적 고정계통을 육성하였다. 이 중 50개계통을 우간다에서 생물검정을 실시한 결과, 아프리카에서 문제시되는 Yellow Mottle Virus (RYMV), Bacterial LeafStreak(BLS), 흰잎마름병 및 도열병에 복합저항성인 계통으로판명되었다. 특히 RYMV에 대한 저항성은 저항성원이 결여되어 있는 병으로 본 연구를 통해 육성한 계통들은 향후 아프리카에 적응하는 내병성 다수성 품종개발에 유용한 재료를 활용 될 것으로 생각된다.
        4,000원
        9.
        2015.10 구독 인증기관·개인회원 무료
        10.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study was carried out to assess the production performances of Japanese quail parent stock raised under open housing system and the study was conducted in a local farm with 2000 Japanese parent stock quail birds (Coturnix coturnix japonica). Observed body weight gain was recorded in each weekend up to 7 weeks of their age; birds gained weight 15.73, 31.45, 47.20, 90.80, 125.27, 153.14 and 175.20 grams, respectively. There have been observed sharp decline of fertility and hatchability of birds with increase of their age. Optimum fertility was recorded at third week and optimum hatchability at fifth week of their age. Average flock uniformity was found 83.68%. The hen day egg production of the flock was recorded 81, 83, 85, 86, 89, 89, 89, 89 and 88% in each weekend, respectively. It may therefore be concluded that Japanese quail parent stock performs well under open housing system in Bangladesh and future study can be taken to better understand their production performances.
        4,000원
        12.
        2010.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Breast cancer is the most frequently diagnosed cancer primarily affecting women and negatively impacting the individuals, families, and the health care system. Despite the well-known benefits of exercise for breast cancer survivors, rate of physical activity declines during adjuvant therapy and may not return to pre-diagnosis levels. In addition, low levels of adherence to exercise have been observed in this cohort. The challenge is to identify strategies that are effective in promoting exercise adherence. Several of the studies use social cognitive theory as a theoretical framework to design exercise interventions that encourage adherence. Within and without this framework, they have implemented interventions within the home and gym-based environments. Strategies used to encourage adherence to exercise programs and which are readily implemented in most situations have included distribution of print materials and pedometers, as well as recommendation from the oncologist. Other strategies that may be less feasible have included provision of trainers, gym memberships, regular phone-calls, and psychologist-lead stress management sessions.
        4,300원
        13.
        2007.10 구독 인증기관 무료, 개인회원 유료
        This paper provides an overview of the Australian Plant Biosecurity System, based on the concept of a biosecurity continuum with pre-border, border and post border components. Particular focus is given to the post border component; preparedness and response to plant pest incursions. Also discussed are initiatives to incorporate all elements of biosecurity including potential production, social and environmental impacts within a uniform and consistent framework, the Australian Biosecurity System for Primary Production and the Environment.
        5,700원
        14.
        2006.09 구독 인증기관·개인회원 무료
        The well-established Universal Powder Press UPP, designed by the Swiss press manufacturer Osterwalder AG in Lyss, went through a major improvement process. The result is a high efficient production machine with state-of-the-art technology. It will be shown the technical design, some process engineering as well as the influence of PRP - =Part-Related-Programming, first published in 1994 - on the set-up time. This development has enabled Osterwalder to round off their range of presses, the mechanical-hydraulic KPP as well as the hydraulic CA-NC II and UPP, to an attractive offer ranging from 120 kN up to 10'000 kN.
        16.
        2006.04 구독 인증기관·개인회원 무료
        This is about the effects deoxidization, carbonization and alloying preparation on fine grain W, WC, and grade YG8 powder reduced by "yellow tungsten oxide" and "blue tungsten oxide". The result indicates that yellow tungsten has single composition and blue tungsten oxide has complex composition. With this feature, yellow tungsten oxide got better uniformity and concentration distribution on fine particle size W and WC powder than blue tungsten oxide's. The grade alloy YG8 that made of this W or WC powder has uniform alloy construction, concentrated WC grain distribution and better alloy properties.
        17.
        2006.04 구독 인증기관·개인회원 무료
        Using microwave synthesized HAp nano powder and polymethyl methacrylate (PMMA) as a pore-forming agent, the porous biphasic calcium phosphate (BCP) ceramics were fabricated depending on the sintering temperature. The synthesized HAp powders was about 70-90 nm in diameter. In the porous sintered bodies, the pores having were homogeneously dispersed in the BCP matrix. Some amounts of pores interconnected due the necking of PMMA powders which will increase the osteoconductivity and ingrowth of bone-tissues while using as a bone substrate. As the sintering temperature increased, the relative density increased and showed the maximum value of 79.6%. From the SBF experiment, the maximum resorption of ion was observed in the sample sintered at .
        18.
        2006.04 구독 인증기관·개인회원 무료
        Using as sintering additives and Si as a raw powder, the continuously porous in-situ bodies were fabricated by multi-pass extrusion process and their microstructures were investigated depending on the addition of carbon (0-9wt%) in the mixture powder. The introduction of fibers observed in the unidirectional continuous pores as well as in the pore-frame regions of the nitrided bodies can be an effective method in increasing the filtration efficiency. In the case of no carbon addition, the network type fibers with high aspect ratio appeared in the continuous pores with diameters of 150-200 nm. However, in the case of 9wt% C addition, the fibers were found without any network type and had diameters of 200-250 nm.
        19.
        2006.04 구독 인증기관·개인회원 무료
        Most PM components are exposed to cyclic loading over long periods of time, yet, the fatigue performance is often at best characterized by a fully reversed bending strength. The effects of density, deviating loading modes, external notches or mean stresses must usually be estimated. The amount of available data is nowadays sufficient to come to fact-based estimates.
        20.
        1999.04 구독 인증기관·개인회원 무료
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