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        검색결과 109

        82.
        1999.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study is concerned with the hydrostatic extrusion process of copper-clad aluminum rod through metallurgical joining. In this study, the rigid plastic finite element program, HICKORY, is used to analyze the steady state extrusion process of the bimetal rod. Simulations are performed for copper-clad aluminum rod with several extrusion ratio to give the distributions of effective strain rate, equivalent stress and hardness. Experiments are also carried out for aluminum-inserted copper rod at room temperature. It is found out that finite element predictions are generally in good agreement with the experimental observations. The detail comparison of the extrusion loads by the finite element method with those by experiments are given.
        4,000원
        84.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The plastic deformation behaviors for powder extrusion of rapidly soildified Al-Si-Fe alloys at high temperature were investigated. During extrusion of Al-Si-Fe alloys, primary Si and intermetallic compound in matrix are broken finely. Additionally, during extrusion metastable phase() intermetallic compound disappears and the equilibrium phase() is formed. In gereral, it was diffcult to establish optimum process variables for extrusion condition through experimentation, because this was costly and time-consuming. In this paper, in order to overcome these problems, we compared the experimental results to the finite element analysis for extrusion behaviors of rapidly solidified Al-Si-Fe alloys. This ingormation is expected to assist in improving rapidly solidified Al-Si alloys extrusion operations.
        4,000원
        85.
        1996.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Investigation on the extrusion of rapidly solidified Al-Si alloys was performed in order to develop an inexpensive production process of high strength parts. It is necessary to establish optimum process variables for the extruding condition through the experiments, because it is high cost and time consuming process. In this paper, the experimental results was compared to the finite element analysis for the extrusion of rapidly solidified Al-Si alloys. The results of this simulation helped to understand the distribution of relative density and effective stress for rapidly solidified Al-Si alloys during the extrusion process. This information is expected to assist in improving the extrusion operations of rapidly solidified Al-Si alloys.
        4,000원
        86.
        1995.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        분말야금법으로 제조된 A6061기 입자분산강화 복합재의 열간압술가공에 있어서 압출특성에 미치는 강화입자의 종류, 빌렛특성 및 암술조건의 영향에 대하여 조사하였다. A6061기 복합재료의 열간 압술 전단 변형저항에 미치는 강화입자종류의 영향은 Si Cw > A12 O3f > A12 O3f > Si Cp의 순으로 되었으며, 모든 강화입자에서 부피분율이 증가함에 따라서 Kw값도 증가하였다. 압출조건, 강화입자의 첨가량 및 첨가입자의 평균입도에 관계없이 A12 O3p가 첨가된 복합재의 열간압출가공에 필요한 소요압력은 Si Cp의 경우보다 컸다. 압출압력은 압출 다이스 반각이 커질수록 감소하는 경향은 나타났다. 이것은 다이스 반각에 의해 생성되는 빌렛과의 접촉면적이 증가하여 전단마찰응력(m k3)이 상승하기 때문이다. 압출시 압출온도 상승은 저온에서 ~50˚C 정도 증가하였으며, 압출온도가 500˚C 이상이 되면 압출재 표면에 극심한 tearing이 발생하였다. 강화입자의 첨가량이 증가할수록 이 현상은 더 심하게 되었다.게 되었다.
        4,000원
        88.
        1995.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Effects of the extrusion temperature and die angle on the tensile properties of SiCIyAl composites in powder extrusion have been investigated. SiCP/Al composites were extruded at various extrusion temperatures (450, 500, ) under the extrusion ratio of 25 : 1. The ram speed was maintained at 13 cm/min for all the extrusion conditions. The surface of the extruded rod appeared to be smooth without tearing at 450 and 50, whereas it was very rough due to tearing at . It was found that the tensile strength and elongation of the composites extruded at are greater than those of composites extruded at This is due to the easier plastic deformation of composite extruded at , compared with the composites extruded at . The effect of die angle was examined under 20=60, 120, die angles at extrusion temperature of under 25:1 extrusion ratio. The tensile strength of the composites extruded with 20=approved to be higher than that of the composties extruded with 28 : 120 and This is attributable to the higher extrusion pressure, which mixed composite powders could be densely consolidated at elevated temperatures, resulting from high friction force between billet and sliding surface of conical die.
        4,000원
        89.
        1994.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        분말야금법으로 제조된 SiCp/6061 Al 복합재료의 열간 압출가공에 있어서 압출성에 미치는 빌렛의 특성과 압출조건의 영향에 대하여 조사하였다. 압출가공성의 난이도를 판단 할 수 있는 기준이 되는 최대압출력과 변형저항 값(Kw)은 350ton 압출기를 이용한 압출압력의 측정과 Watanabe등의 경험식에 의해 도출되었다. 6061Al합금기 복합재료 빌렛의 전단변형저항고 압출압력은 강화재(SiCp)의 부피분율이 증가함에 따라 증가하고 있으나, 증가되는 비율은SiCp인 경두가 SiCw,Al2O3f/보다 작았다. 강화입자 크기가 작을 수록 변형저항 값이 증가하였고 압출성도 양호하였다. 변형저항 값의 증가는 기지금속의 가공경화에 기인하며, 최대압출력을 나타내는 피이크는 강화재의 입자가 미세할 수록, 즉 가공경호가 클 수록 뾰족한 형상을 나타내었다. 압출온도가 증가할 수록 변형저항 값이 낮아져서 작은 압출력으로도 복합재료의 압출이 가능하나, 500˚C이상인 경우 압출재 표면에 극심한 tearing현상이 발생하였다.
        4,000원
        90.
        1994.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        현재까지 잘 알려진 압출이론식이 생산현장에 응용될 수 있는가를 조사하기 위하여, Al-Si합금을 대상소재로 하여 각 압출이론식에 나타난 유도응력 Kf, 변형저항 Kw , Dead Metal Zone(DMZ)의 경각(α)등을 측정하였으며, 이들 값을 이용하여 최대압출력을 계산하였다. 550ton의 압출기를 이용하여 측정한 최대 압출력과의 비교분석을 행하였으며, 그 결과 이론식에 의해 최대압출력을 계산하기 위해 측정된 유동응력 및 변형저항 값은 신뢰할 수 있을 것으로 사료되었는데, 이것은 0.5이하에서 결정된 변형효율 η f로서 판단 할 수 있었다. 최대 압출력은 Si함량이 증가할 수록 증가하게 되나, 압출온도가 증가할 수록 감소하고 있음을 알 수 있었다. Siebel식으로부터 계산된 최대압출력은 본 실험을 통하여 얻어진 최대압출력에 비교적 근접하고 있으나. Geleji식으로부터 계산된 최대압출력은 DMZ의경각 α가 50˚일 경우 , 본 실험에 의해 얻어진 실제의 최대압출력에 급접하고 있었다. Geleji의 식은 DMZ의 경각에 매우 민감하고, 대상재료마다. DMZ를 일일이 측정해야 하는 번거로움 때문에 생산현장에서는 Siebel의 식을 이용하는 것이 보다 편리할 것으로 사료된다.
        4,000원
        93.
        1988.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        식품 압출 성형공법을 이용한 전통 식품의 가공 및 개선에 관한 국내 연구 동향을 조사 평가한 것이다. 여기에서는 특히 Extruder를 이용한 미강안정화공법, 즉석 떡 제조법, 곡류를 기질로한 젖산 발효 음료 및 탁주 제조법에 관한 연구 결과를 다루었다.
        4,000원
        94.
        2018.10 KCI 등재 서비스 종료(열람 제한)
        Background: The objective of this study was to make colloidal dispersions of the active compounds of radix of Angelica gigas Nakai that could be charaterized as nano-composites using hot melt extrusion (HME). Food grade hydrophilic polymer matrices were used to disperse these compound in aqueous media. Methods and Results: Extrudate solid formulations (ESFs) mediated by various HPMCs (hydroxypropyl methylcelluloses) and Na-Alg polymers made from ultrafine powder of the radix of Angelica gigas Nakai were developed through a physical crosslink method (HME) using an ionization agent (treatment with acetic acid) and different food grade polymers [HPMCs, such as HP55, CN40H, AN6 and sodium alignate (Na-Alg)]. X-ray powder diffraction (XRD) analysis confirmed the amorphization of crystal compounds in the HP55-mediated extrudate solid formulation (HP55-ESF). Differential scanning calorimetry (DSC) analysis indicated a lower enthalpy (ΔH = 10.62 J/g) of glass transition temperature (Tg) in the HP55-ESF than in the other formulations. Infrared fourier transform spectroscopy (FT-IR) revealed that new functional groups were produced in the HP55-ESF. The content of phenolic compounds, flavonoid (including decursin and decursinol angelate) content, and antioxidant activity increased by 5, 10, and 2 times in the HP55-ESF, respectively. The production of water soluble (61.5%) nano-sized (323 ㎚) particles was achieved in the HP55-ESF. Conclusions: Nano-composites were developed herein utilizing melt-extruded solid dispersion technology, including food grade polymer enhanced nano dispersion (< 500 ㎚) of active compounds from the radix of Angelica gigas Nakai with enhanced solubility and bioavailability. These nano-composites of the radix of Angelica gigas Nakai can be developed and marketed as products with high therapeutic performance.
        95.
        2018.10 서비스 종료(열람 제한)
        Background : The objective of this study was to make colloidal dispersion of the active compound was characterized nano-composite from radix of Angelica gigas Nakai using hot melt extrusion (HME). Therefore, food grade hydrophilic polymer matrices was used to disperse compound in aqueous media. Methods and Results : Extrudate solid formulations (ESFs) mediated various HPMCs (hydroxypropyl methylcellulose) and Na-Alg polymer from ultrafine powder of radix of Angelica gigas Nakai was developed through physical crosslink method (HME) with ionization agent (treatment of acetic acid) and food grade polymer [HPMCs such as HP55, CN40H, AN6 and sodium alignate (Na-Alg)]. X-ray powder diffraction (XRD) analysis confirmed the amorphization of crystal compounds in extrudate solid formulations mediated HP55 (HP55-ESF). Differential scanning calorimetry (DSC) analysis indicated a lower enthalpy (ΔH = 10.62 J/g) of glass transition temperature (Tg) in HP55-ESF. Infrared fourier transform spectroscopy (FT-IR) reveled new functional groups produced in HP55-ESF. Phenolic compound, flavonoid (including decursin and decursinol angelate) and antioxidant activity increased at 5, 10 and 2 times in HP55-ESF. Water solubility (61.5%) nano size (323 ㎚) particle was achieved in the HP55-ESF. Conclusion : Nano-composites have been developed utilizing melt-extruded solid dispersions technology by food grade polymer enhanced nano dispersion (< 500 ㎚) of active compound from radix of Angelica gigas Nakai with enhanced solubility and bioavailability. This nano-composites of radix of Angelica gigas Nakai developmental and marketed products to enable therapeutic performance.
        96.
        2018.10 서비스 종료(열람 제한)
        Background : The root of Angelica gigas Nakai is used as a traditional herbal medicine in Korea for the treatment of many diseases. Poor water solubility of the active compounds from A. gigas Nakai is a major obstacle to bioavailability. Methods and Results : This work aimed to enhance the solubility of active compounds by a chemical (viz. surfactant) and physical (HME, hot melt extrusion) crosslinking method (CPC) in A. gigas Nakai. Infrared fourier transform spectroscopy (FT-IR) revealed multiple peaks in extrudate solids representing new functional groups including carboxylic acid, alkynes and benzene derivatives. Differential scanning calorimetry (DSC) analysis of the extrudate showed lower glass transition temperature (Tg) and lower enthalpy (ΔH) [Tg: 43℃; ΔH: <6 (J/g)] compared to the non-extrudate (Tg 68.5℃; ΔH: 123.2) formulations. X-ray powder diffraction (XRD) analysis revealed amorphization of crystal materials in extrudate solid. In addition, enhanced solubility (53%), nanonization (403 ㎚), and higher amount of extracted phenolic compounds were achieved in the extrudate solid compared to non extrudate (36%, 1499 ㎚, respectively). Among the different extrudates, acetic acid and span 80 mediated formulations showed superior extractions efficiency. Conclusion : We conclude that the HME successfully enhanced the production of amorphous nano dispersions of phenolic compound including decursin from extrudate solid formulations. human dermal fibroblasts, which is, associated with the regulation of procollagen biosynthesis resulting from AMRP-induced TGF-β1 expression and the mitogenic activity in HDF cells, and therefore, is expected to reduce the age-dependent loss of extracellular matrix proteins.
        97.
        2018.08 KCI 등재 서비스 종료(열람 제한)
        Background: The root of Angelica gigas Nakai is used as a traditional herbal medicine in Korea for the treatment of many diseases. However, the poor water solubility of the active components in A. gigas Nakai is a major obstacle to its bioavailability. Methods and Results: This work aimed at enhancing the solubility of the active compounds of A. gigas Nakai by a chemical (using a surfactant) and physical (hot melt extrusion, HME) crosslinking method. Fourier transform infrared spectroscopy revealed multiple peaks in the case of the extrudate solids, attributable to new functional groups including carboxylic acid, alkynes, and benzene derivatives. Differential scanning calorimetry analysis showed that the extrudate soilid had a lower glass transition temperature (Tg) and enthalpy (ΔH) (Tg : 43℃, ΔH : < 6 J/g) as compared to the non-extrudate (Tg : 68.5℃, ΔH : 123.2) formulations. X-ray powder diffraction analysis revealed the amorphization of crystalline materials in the extrudate solid. In addition, enhanced solubility (53%), nanonization (403 ㎚), and a higher amount of extracted phenolic compounds were achieved in the extrudate solid than in the non-extrudate (solubility : 36%, nanonization : 1,499 ㎚) formulation. Among the different extrudates, acetic acid and span 80 mediated formulations showed superior extractions efficiency. Conclusions: HME successfully enhanced the production of amorphous nano dispersions of phenolic compound including decursin from extrudate solid formulations.
        98.
        2017.05 서비스 종료(열람 제한)
        Background : Cu ion is an essential mineral of animal feed. But rapid degradation of Cu ion in animal intestine causes poor immune activity and potential environment hazard. Therefore, to enhance immune system and control metal ion deliverly in intestine, we developed Cu ion nano suspension. In animal feed, > 127 ㎎/g of Cu ion are found but only 5 - 7 ㎎ are used out of them. Therefore, huge loss of Cu ion causes environment, economy and animal health problem. Methods and Results : Seven formulation were prepared to prepare nano suspension (particle size < 200 ㎚) of CuSO4. The particle diameter, polydispersity index, and zeta potential values of the samples were measured using dynamic light scattering (DLS) and laser Doppler methods (ELS-Z1000; Otsuka Electronics, Tokyo, Japan). Absorbance and Cu ion concentration was measured using UV-VIS Spectrophotometer. Cu ion nano particle (< 200 ㎚) was found in a formulation comprised of Cu ion : surfactant (lipophilic : hydrophilic) and PEG. In consistence with this result, total absorbance and concentration was found higher in the same formulation compared to control. Conclusion : From our experiment we may conclude that mixture of Cu ion : surfactant (lipophilic : hydrophilic) and PEG successfully prepared nano suspension which slow down the degradation of Cu ion in intestine with improving feed quality, animal health and prevent potential environment pollution.
        99.
        2016.10 서비스 종료(열람 제한)
        Background : Angelica gigas is a biennial or short lived perennial plant found in China, Japan, and Korea. The root of Angelica gigas has been used in oriental traditional medicine and is marketed as a functional food product in Europe and North America. Cham-Dang-Gui (Korean Angelica, the dried root of Angelica gigas Nakai (AGN)) has been principally cultivated in Korea and used as a Korean medicinal herb. It contains several chemicals, such as pyranocoumarins, essential oils, and polyacetylenes. Methods and Results : Fresh Angelica gigas Nakai was purchased from Pyeongchang (Korea). Standard samples of D, DA were obtained from Korea Promotion Institute for Traditional Medicine Industry (Gyeongsan, Korea). Soluplus was purchased from BASF (Ludwigshafen, Germany). AGN was dried in the oven at 55°C for 24 h and cooled at room temperature. The AGN sample was then stored at 4°C until milling. Oral solid formulations based on Angelica gigas Nakai and Soluplus were prepared by the hot melt extrusion (HME) method. AGN was pulverized into coarse and ultrafine particles, and their particle size and morphology were investigated. Ultrafine AGN particles were used in the HME process with high shear to produce AGN-based formulations. In simulated gastrointestinal fluids (pH 1.2 and pH 6.8) and water, significantly higher amounts of the major active components of AGN, decursin (D) and decursinol angelate (DA), were extracted from the HME-processed AGN/Soluplus group than the AGN EtOH extract group (p < 0.05). Based on an in vivo pharmacokinetic study in rats, the relative oral bioavailability of decursinol (DOH), a hepatic metabolite of D and DA, in administered mice was 8.75-fold higher than in AGN EtOH ext-treated group. Conclusion : Soluplus-included solid formulation prepared by HME can be a promising carrier for oral delivery of phytochemicals. These findings suggest that HME-processed AGN/Soluplus formulation could be a promising therapeutic candidate for oral bioavailability.
        100.
        2015.03 KCI 등재 서비스 종료(열람 제한)
        CO2 emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30% of CO2 emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of CO2 in the construction area as we reduce the second and third curing to emit CO2 in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter “LA”) to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.
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